Dietmar Werner Hutmacher

Sphingosine-1-Phosphate Mediates Proliferation Maintaining the Multipotency of Human Adult Bone Marrow and Adipose Tissue-derived Stem Cells

Publisher: Oxford University Press (OUP)

Date: 28-06-2010

DOI: 10.1093/JMCB/MJQ011

Abstract: High renewal and maintenance of multipotency of human adult stem cells (hSCs), are a prerequisite for experimental analysis as well as for potential clinical usages. The most widely used strategy for hSC culture and proliferation is using serum. However, serum is poorly defined and has a considerable degree of inter-batch variation, which makes it difficult for large-scale mesenchymal stem cells (MSCs) expansion in homogeneous culture conditions. Moreover, it is often observed that cells grown in serum-containing media spontaneously differentiate into unknown and/or undesired phenotypes. Another way of maintaining hSC development is using cytokines and/or tissue-specific growth factors this is a very expensive approach and can lead to early unwanted differentiation. In order to circumvent these issues, we investigated the role of sphingosine-1-phosphate (S1P), in the growth and multipotency maintenance of human bone marrow and adipose tissue-derived MSCs. We show that S1P induces growth, and in combination with reduced serum, or with the growth factors FGF and platelet-derived growth factor-AB, S1P has an enhancing effect on growth. We also show that the MSCs cultured in S1P-supplemented media are able to maintain their differentiation potential for at least as long as that for cells grown in the usual serum-containing media. This is shown by the ability of cells grown in S1P-containing media to be able to undergo osteogenic as well as adipogenic differentiation. This is of interest, since S1P is a relatively inexpensive natural product, which can be obtained in homogeneous high-purity batches: this will minimize costs and potentially reduce the unwanted side effects observed with serum. Taken together, S1P is able to induce proliferation while maintaining the multipotency of different human stem cells, suggesting a potential for S1P in developing serum-free or serum-reduced defined medium for adult stem cell cultures.

Functional and phenotypic characterization of human keratinocytes expanded in microcarrier culture

Publisher: Wiley

Date: 19-02-2009

DOI: 10.1002/JBM.A.31864

Abstract: Skin cells for transplantation are routinely prepared by growing patient keratinocytes in a semi-defined cocktail of growth factors, including serum and feeder cells. However, these reagents require substantial risk remediation and can contribute to transplant rejection. Microcarrier culture is an emerging technology that may allow the elimination of feeder cells whilst facilitating expansion of cultured keratinocytes. However, the behavior of keratinocytes in microcarrier culture and the potential of these cells to form an epidermis have been poorly defined. We characterized freshly isolated human keratinocytes cultured on CultiSpher-G microcarriers in the absence of murine feeder cells and assessed the potential of the keratinocytes to form an epidermis in an in vitro model. In a single passage, keratinocytes multiplied 44.9-fold in microcarrier-bioreactor culture in 17 days, whereas two-dimensional cultures reached confluence in 9 days and only expanded 7.4-fold. Histological characterization of keratinocytes on the microcarriers revealed that the cells were randomly distributed within these porous structures, however, not all pores contained cells. High-resolution microcomputed tomography imaging of the microcarriers confirmed limited interconnectivity of the pores. Immunoreactivity of specific epidermal markers was confirmed during cell expansion via immunohistochemistry. Despite the expression of differentiation markers, microcarrier-expanded keratinocytes retained the capacity to form an epidermis, as was evaluated using an in vitro human skin equivalent model. The epidermis formed by microcarrier-expanded keratinocytes in this model exhibited morphology similar to native skin. Significantly, the microcarrier technique successfully eliminates the need for a feeder cell layer and hence facilitates development of an improved culture system.

Periodontal tissue engineering

Publisher: Wiley

Date: 11-2016

DOI: 10.1002/9781119282181.CH7

Temporal expression of proteoglycans in the rat limb during bone healing

Publisher: Elsevier BV

Date: 09-2006

DOI: 10.1016/J.GENE.2006.04.029

Abstract: Proteoglycans found in the bone extracellular matrix and on the cell surface can complex with HBGFs such as the FGFs, TGFs and BMPs which are known to play key roles in regulating fracture healing. Here we have studied the expression of key PGs during the bone repair process in order to determine the relationship between PG expression and healing status. We created non-critical sized trephine defects just proximal to the distal end of the tibial crest of adult male Wistar rats and examined the healing process histologically as well as by monitoring the temporal expression of mRNA transcripts for ALP, OP and OC, together with HSPG, CSPG and FGF-FGF receptor expression. Following surgery, animals were allowed to recover, and then euthanized after 7, 14, 21 and 28 days post-surgery, at which time tissue was harvested for histological examination and total RNA extracted and the mRNA transcripts examined by quantitative real-time PCR. HS and CSPG expression was generally observed to increase in the days immediately following injury, reaching peak expression two weeks post-surgery. This was followed by a gradual return to basal levels by day 28. The expression patterns of PGs were broadly similar with those of ALP, OP and FGFRs. The increase of mRNA expression for many key PGs detected during bone healing coincided with the elevation of bone markers and FGFRs, and provides further evidence that PGs involved in bone repair act in part through susceptible growth factors, including the FGF/FGFR system. The data presented here indicates that increased proteoglycan expression is involved in the early stages of bone healing at a time when previous studies have shown that the levels of HBGFs are maximal. Hence there exists a rationale for an exploration of the use of exogenous PGs as an adjunct therapy to potentiate the powerful effects of these factors and to augment the natural healing response.

Mineralized human primary osteoblast matrices as a model system to analyse interactions of prostate cancer cells with the bone microenvironment

Publisher: Elsevier BV

Date: 11-2010

DOI: 10.1016/J.BIOMATERIALS.2010.06.055

Abstract: Prostate cancer metastasis is reliant on the reciprocal interactions between cancer cells and the bone niche/micro-environment. The production of suitable matrices to study metastasis, carcinogenesis and in particular prostate cancer/bone micro-environment interaction has been limited to specific protein matrices or matrix secreted by immortalised cell lines that may have undergone transformation processes altering signaling pathways and modifying gene or receptor expression. We hypothesize that matrices produced by primary human osteoblasts are a suitable means to develop an in vitro model system for bone metastasis research mimicking in vivo conditions. We have used a decellularized matrix secreted from primary human osteoblasts as a model for prostate cancer function in the bone micro-environment. We show that this collagen I rich matrix is of fibrillar appearance, highly mineralized, and contains proteins, such as osteocalcin, osteonectin and osteopontin, and growth factors characteristic of bone extracellular matrix (ECM). LNCaP and PC3 cells grown on this matrix, adhere strongly, proliferate, and express markers consistent with a loss of epithelial phenotype. Moreover, growth of these cells on the matrix is accompanied by the induction of genes associated with attachment, migration, increased invasive potential, Ca(2+) signaling and osteolysis. In summary, we show that growth of prostate cancer cells on matrices produced by primary human osteoblasts mimics key features of prostate cancer bone metastases and thus is a suitable model system to study the tumor/bone micro-environment interaction in this disease.

Reduced contraction of skin equivalent engineered using cell sheets cultured in 3D matrices

Publisher: Elsevier BV

Date: 09-2006

DOI: 10.1016/J.BIOMATERIALS.2006.04.020

Abstract: In order to alleviate their extensive contraction, human fibroblast sheets were cultured in combination with three-dimensional matrices (knitted poly(lactic-co-glycolic acid) (PLGA) mesh and collagen-hyaluronic acid (CHA) sponge) to form contiguous dermal constructs for tissue engineering a bilayered skin equivalent. The resulting constructs were viable, and supported the development of bilayered skin equivalents which did not contract over the 4-week culture period. When implanted into full-thickness wounds in nude rats, cultured skin equivalents based on PLGA meshes registered a take rate of 100% and showed an extent of wound contraction that was statistically similar to autografts, while wounds grafted with PLGA meshes without cell sheets contracted more than autografts. On the other hand, skin equivalents based on CHA sponges were all sloughed off within 2 weeks of transplantation. In all cell sheet-incorporated specimens, cells from the constructs infiltrated and produced extracellular matrix within the neo-dermis, shown by positive human leukocyte antigen and collagen I expression. This technique offers an alternative approach for scaffold-based tissue engineering to produce mechanically stable grafts with matured neo-tissue.

A bioengineered microenvironment to quantitatively measure the tumorigenic properties of cancer-associated fibroblasts in human prostate cancer

Publisher: Elsevier BV

Date: 07-2013

DOI: 10.1016/J.BIOMATERIALS.2013.03.005

Abstract: Stromal-epithelial cell interactions play an important role in cancer and the tumor stroma is regarded as a therapeutic target. In vivo xenografting is commonly used to study cellular interactions not mimicked or quantified in conventional 2D culture systems. To interrogate the effects of tumor stroma (cancer-associated fibroblasts or CAFs) on epithelia, we created a bioengineered microenvironment using human prostatic tissues. Patient-matched CAFs and non-malignant prostatic fibroblasts (NPFs) from men with moderate (Gleason 7) and aggressive (Gleason 8-9 or castrate-resistant) prostate cancer were cultured with non-tumorigenic BPH-1 epithelial cells. Changes in the morphology, motility and phenotype of BPH-1 cells in response to CAFs and NPFs were analyzed using immunofluorescence and quantitative cell morphometric analyses. The matrix protein gene expression of CAFs, with proven tumorigenicity in vivo, had a significantly different gene expression profile of matrix proteins compared to patient matched NPFs. In co-culture with CAFs (but not NPFs), BPH-1 cells had a more invasive, elongated phenotype with increased motility and a more directed pattern of cell migration. CAFs from more aggressive tumors (Gleason 8-9 or CRPC) were not quantitatively different to moderate grade CAFs. Overall, our bioengineered microenvironment provides a novel 3D in vitro platform to systematically investigate the effects of tumor stroma on prostate cancer progression.

Additive manufacturing in biomedical sciences and the need for definitions and norms

Publisher: Informa UK Limited

Date: 08-2015

DOI: 10.1586/17434440.2015.1059274

Abstract: The application of additive biomanufacturing represents one of the most rapidly advancing areas of biomedical science, in which engineers, scientists, and clinicians are contributing to the future of health care. The combined efforts of a large number of groups around the globe have developed a strong research thrust that has resulted in a large number of publications. Reviewing this body of literature, there is an increasing trend of research groups inventing their own definitions and terminology. This has made it difficult to find and compare the results. Therefore, to move the field constructively forward, it is a conditio sine qua non to clarify various terminologies and standards. Based on this background, this article advocates tightening the terminology and has the objective of penning out definitions that will ultimately allow the development of official industry standard terms, such as American Society for Testing and Materials and or International Organization for Standardization for technologies developed for Tissue Engineering and Regenerative Medicine.

Recombinant Human Bone Morphogenetic Protein 7 Exerts Osteo-Catabolic Effects on Bone Grafts That Outweigh Its Osteo-Anabolic Capacity

Publisher: Springer Science and Business Media LLC

Date: 18-06-2019

DOI: 10.1007/S00223-019-00574-5

Abstract: This study aimed to investigate the effects of recombinant human bone morphogenetic protein (rhBMP-7) on human cancellous bone grafts (BGs) while differentiating between anabolic and catabolic events. Human BGs alone or supplemented with rhBMP-7 were harvested 14 weeks after subcutaneous implantation into NOD/Scid mice, and studied via micro-CT, histomorphometry, immunohistochemistry and flow cytometry. Immunohistochemical staining for human-specific proteins made it possible to differentiate between grafted human bone and newly formed murine bone. Only BGs implanted with rhBMP-7 formed an ossicle containing a functional hematopoietic compartment. The total ossicle volume in the BMP

Runx2 Overexpression in Bone Marrow Stromal Cells Accelerates Bone Formation in Critical-Sized Femoral Defects

Publisher: Mary Ann Liebert Inc

Date: 09-2010

DOI: 10.1089/TEN.TEA.2010.0025

Ovine bone- and marrow-derived progenitor cells and their potential for scaffold-based bone tissue engineering applications in vitro and in vivo

Publisher: Hindawi Limited

Date: 21-06-2010

DOI: 10.1002/TERM.276

Abstract: Recently, research has focused on bone marrow derived multipotent mesenchymal precursor cells (MPC) and osteoblasts (OB) for clinical use in bone engineering. Prior to clinical application, cell based treatment concepts need to be evaluated in preclinical, large animal models. Sheep in particular are considered a valid model for orthopaedic and trauma related research. However, only sheep aged > 6 years show secondary osteon formation characteristic of human bone. Osteogenic cells isolated from animals of this age group remain poorly characterized. In the present study, ex vivo expanded MPC isolated from ovine bone marrow proliferated at a higher rate than OB derived from tibial compact bone as assessed in standard 2D cultures. MPC expressed the respective phenotypic profile typical for different mesenchymal cell populations (CD14(-)/CD31(-)/CD45(-)/CD29(+)/CD44(+)/CD166(+)) and showed a multilineage differentiation potential. When compared to OB, MPC had a higher mineralization potential under standard osteogenic culture conditions and expressed typical bone related markers such as osteocalcin, osteonectin and type I collagen at the mRNA and protein level. After 4 weeks in 3D culture, MPC constructs demonstrated higher cell density and mineralization, whilst cell viability on the scaffolds was assessed > 90%. Cells displayed a spindle-like morphology and formed interconnected networks. In contrast, when implanted subcutaneously into NOD/SCID mice, MPC presented a lower osteogenic potential than OB. In summary, this study provides a detailed characterisation of ovine MPC and OB from a bone engineering perspective and suggests that MPC and OB provide promising means for future bone disease related treatment applications.

Establishment and Characterization of an Open Mini-Thoracotomy Surgical Approach to an Ovine Thoracic Spine Fusion Model

Publisher: Mary Ann Liebert Inc

Date: 2014

DOI: 10.1089/TEN.TEC.2012.0746

Osteogenic differentiation of mesenchymal progenitor cells in computer designed fibrin-polymer-ceramic scaffolds manufactured by fused deposition modeling

Publisher: Springer Science and Business Media LLC

Date: 09-2005

DOI: 10.1007/S10856-005-3584-3

Abstract: Biomimetic scaffolds offer great potentials in the development of bone analogs for tissue engineering. The studies presented in this paper focus specifically on the osteogenic potential of the novel PCL/CaP matrices and its degradation behavior. Biodegradable Polymer-ceramic Scaffolds were fabricated using the solid free form fabrication technology: Fused Deposition Modeling (FDM). The scaffold architecture was characterized by a honeycomb-like design and a complete interconnectivity of the pores. Human mesenchymal stem cells (MSCs) were seeded together with fibrin glue into PCL/CaP scaffolds and cultured in vitro for periods of up to eight weeks. Cellular adhesion, proliferation and osteogenic differentiation were assessed in these constructs using a range of histological and microscopic techniques. In additional experiments, degradation was assessed by measuring mass loss, diameter change, molecular weight change and by scanning electron micrographs. MSCs were able to adhere, migrate, and differentiate along the osteogenic lineage with in these scaffolds. The PCL/CaP scaffolds showed up to 27 fold increased degradation of compared to PCL scaffolds.

Ovine cortical osteoblasts outperform bone marrow cells in an ectopic bone assay

Publisher: Hindawi Limited

Date: 10-02-2011

DOI: 10.1002/TERM.392

Abstract: Reviewing the available literature, one could conclude that marrow-derived mesenchymal stem cells (BMSCs) are the 'gold standard' source for bone tissue engineering applications, due to their multilineage differentiation potential and easy accessibility. However, comprehensive studies comparing their osteogenic potential with bone-derived osteoblasts (OBs) to justify the preferred application of BMSCs based on performance are few. To address these shortfalls, in the present study, ovine BMSCs and OBs seeded onto scaffolds were characterized in vitro and transplanted subcutaneously into NOD/SCID mice in combination with and without recombinant human bone morphogenetic protein 7 (rhBMP-7). It was hypothesized that cell origin, ossification type and degree of vascularization and ossification depends on the nature and commitment of transplanted cells and stimulating growth factors, such as rhBMP-7. After retrieval, specimens were analysed by biomechanical testing, µCT analysis, scanning electron microscopy/energy-dispersive X-ray spectroscopy and histo- and immunohistochemistry for osteocalcin, type II collagen and BrdU. The results showed a high degree of cell survival and proliferation ectopically, resulting in active contribution to endochondral osteogenesis. When compared to BMSCs, OBs showed a higher degree of bone deposition while OB-derived bone was of higher maturation. Stimulation with rhBMP-7 increased the rate of bone synthesis for both BMSCs and OBs, additionally promoting neovascularization and osteoclast activity. These results suggest that the origin and commitment of transplanted cells highly influence the type and degree of ossification, that rhBMP-7 represents a powerful adjuvant for bone tissue-engineering applications, and that mature bone is an adequate alternative cell source for bone tissue-engineering applications.

Bone Regeneration Based on Tissue Engineering Conceptions — A 21st Century Perspective

Publisher: Springer Science and Business Media LLC

Date: 25-09-2013

DOI: 10.4248/BR201303002

Design and Development of a Three-Dimensional Printing High-Throughput Melt Electrowriting Technology Platform

Publisher: Mary Ann Liebert Inc

Date: 04-2019

DOI: 10.1089/3DP.2017.0149

Differentiation potential of mesenchymal progenitor cells following transplantation into calvarial defects

Publisher: Elsevier BV

Date: 07-2012

DOI: 10.1016/J.JMBBM.2012.02.008

Abstract: The complexity of stem cell lineage commitment requires studies to investigate the intrinsic and extrinsic regulatory events during differentiation. The objective of this long-term in vivo study was to investigate cellular differentiation and tissue formation of transplanted undifferentiated bone-marrow-derived mesenchymal progenitor cells (BMPCs) in combination with a medical grade polycaprolactone (mPCL) scaffold and to compare them to osteoblasts a more differentiated cell type in a calvarial defect model. Tissue formation was assessed via histology, mechanical and radiological methods after 3 12, and 24 months. After 3 months our results indicated that transplanted mesenchymal progenitor cells were influenced by the niche of the host environment. Scaffold/BMPCs formed islands of bone tissue inside the defect area. However when the surrounding host calvarium contained a high content of fatty tissue, the fat content in the defect areas was also significantly higher. In contrast, defects repaired with scaffold/cOBs did not show this phenomenon. Analysis after 12 and 24 months confirmed these observations indicating that a predominantly fatty environment leads to adipogenic development in the progenitor group. Biomechanical data revealed that the tissue was less firm in the BMPC group compared to the cOB seeded group. Evaluation of cell plasticity in vivo has important consequences in clinical cell transplantation protocols. This study indicates that cell fate decisions are partially regulated by extrinsic control mechanisms of the immediate environment suggesting that induction of BMPCs into a specific lineage could be beneficial prior transplantation.

Force-controlled automatic microassembly of tissue engineering scaffolds

Publisher: IOP Publishing

Date: 05-02-2010

DOI: 10.1088/0960-1317/20/3/035001

Monitoring Healing Progression and Characterizing the Mechanical Environment in Preclinical Models for Bone Tissue Engineering

Publisher: Mary Ann Liebert Inc

Date: 02-2016

DOI: 10.1089/TEN.TEB.2015.0123

Design, fabrication and characterization of PCL electrospun scaffolds - A review

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C0JM04502K

Clinical translation of a patient-specific scaffold-guided bone regeneration concept in four cases with large long bone defects

Publisher: Elsevier BV

Date: 05-2022

DOI: 10.1016/J.JOT.2022.04.004

Effects of Runx2 genetic engineering and in vitro maturation of tissue‐engineered constructs on the repair of critical size bone defects

Publisher: Wiley

Date: 14-11-2005

DOI: 10.1002/JBM.A.30549

Abstract: Genetic and tissue engineering strategies are being pursued to address the clinical limitations of current bone grafting materials. Based on our previous work demonstrating that overexpression of the Runx2 osteoblastic transcription factor and in vitro construct maturation synergistically enhanced in vivo mineralization in an ectopic site (Byers et al., Tissue Eng 2004 :1757-1766), we examined the effects of these two parameters on the repair of critical size bone defects. Primary rat bone marrow stromal cells transduced with Runx2 or control (no Runx2 insert) retroviral vector were seeded onto 3D fused deposition-modeled polycaprolactone scaffolds. Runx2-modified cells produced biologically-equivalent mineralized matrices at nearly 2-fold higher rates than control cells. Constructs cultured in vitro for 1 day (immature) or 21 days (mineralized) were subsequently implanted into critical size calvaria defects in syngeneic rats, and bone healing was analyzed by micro-CT and histomorphometry at 28 days. Runx2-modified and control constructs precultured for 1 day healed to a greater extent than defects receiving no implant. Cell-free scaffolds yielded equivalent levels of bone formation as constructs precultured for 1 day. Interestingly, defects treated with control cell-seeded constructs precultured for 21 days exhibited low bone formation compared to other construct treatments, and repair was comparable to empty defects. In contrast, Runx2-modified constructs precultured for 21 days contained twice as much bone as control constructs precultured for 21 days and equivalent levels of new bone as cell-free and 1 day precultured constructs. These results demonstrate interplay between Runx2 genetically-modified cells and in vitro construct maturation in bone healing responses.

A clarion call for understanding regulatory processes for additive manufacturing in the health sector

Publisher: Informa UK Limited

Date: 30-04-2019

DOI: 10.1080/17434440.2019.1609353

Abstract: As Additive Manufacturing (AM) in the health sector evolves to the point where products can be translated into the clinic, these manufactured goods need to be assessed by regulators in order for such products to be manufactured, sold, and used in accordance with the law. In this article, the authors argue that if AM products in the health sector are to be regulated in the near future, stakeholders involved in translational research need to understand the challenges faced by both regulators and industry. We portray different points of possible dissonance for AM medical products with existing regulatory frameworks. Hence, we advocate for stakeholders to proactively provide solutions for regulatory processes for products emerging from AM in the health sector. The publication discusses the need for clear definitions and standards to enable translation of AM research into the health sector. Key literature around legal and regulatory challenges applicable to this topic was synthesized. We argue that stakeholders need to develop regulatory-rooted risk profiles of the respective AM medical products. The terminology must be defined clearly and used consistently. Standards need to be designed for the purpose of advancing regulatory processes.

Two for the price of one: a keystone design equals two conjoined V-Y flaps

Publisher: Wiley

Date: 06-2011

DOI: 10.1111/J.1445-2197.2011.05772.X

Translating tissue engineering technology platforms into cancer research

Publisher: Wiley

Date: 08-2009

DOI: 10.1111/J.1582-4934.2009.00853.X

Effect of gelatin source and photoinitiator type on chondrocyte redifferentiation in gelatin methacryloyl-based tissue-engineered cartilage constructs

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8TB02607F

Abstract: This work investigates neocartilage formation in bovine and porcine gelatin methacryloyl-based hydrogels photocrosslinked using ultraviolet or visible light photoinitiator systems.

Investigation of Sustained BMP Delivery in the Prevention of Medication-Related Osteonecrosis of the Jaw (MRONJ) in a Rat Model

Publisher: Wiley

Date: 24-09-2019

DOI: 10.1002/MABI.201900226

Abstract: Medication-related osteonecrosis of the jaw (MRONJ) poses an ongoing challenge for clinicians and researchers. Currently, there is a lack of preventative measures available for at-risk patients undergoing tooth extractions, especially those with prior bisphosphonate treatment due to osteoporosis or bone metastasis diagnoses. Here, these issues are addressed using a preventative tissue engineering strategy against MRONJ development. This study evaluates the efficacy of a poly(ethylene glycol)-heparin hydrogel as a tool for the delivery of arginylglycylaspartic acid (RGD) and recombinant human bone morphogenic protein-2 (rhBMP-2). Three groups of skeletally mature rats each receive two doses of intravenous zoledronic acid prior to surgery and undergo extraction of the right first mandibular molar with gingival closure. Experimental groups either have the sockets left empty, filled with hydrogel minus rhBMP-2, or filled with hydrogel plus rhBMP-2. Eight weeks postoperatively specimens are analyzed using radiological, histological, and scanning electron microscopy (SEM) techniques. µCT analysis shows increased bone formation with hydrogel/rhBMP-2 delivery compared to the empty socket. Hydrogel-treated groups display increased presence of osteocytes and increased osteoclastic action compared to the empty sockets. These results represent the first step toward improved delivery of rhBMP-2 and a potential MRONJ preventative for patients undergoing bisphosphonate treatment.

Mesodermal and neural crest derived ovine tibial and mandibular osteoblasts display distinct molecular differences

Publisher: Elsevier BV

Date: 08-2013

DOI: 10.1016/J.GENE.2013.04.026

Abstract: Mandibular osteoblasts originate from the neural crest and deposit bone intramembranously, mesoderm derived tibial osteoblasts by endochondral mechanisms. Bone synthesized by both cell types is identical in structure, yet functional differences between the two cell types may exist. Thus, both matched juvenile and adult mandibular and tibial osteoblasts were studied regarding their proliferative capacity, their osteogenic potential and the expression of osteogenic and origin related marker genes. Juvenile tibial cells proliferated at the highest rate while juvenile mandibular cells exhibited higher ALP activity depositing more mineralized matrix. Expression of Hoxa4 in tibial cells verified their mesodermal origin, whereas very low levels in mandibular cells confirmed their ectodermal descent. Distinct differences in the expression pattern of bone development related genes (collagen type I, osteonectin, osteocalcin, Runx2, MSX1/2, TGF-β1, BAMBI, TWIST1, β-catenin) were found between the different cell types. The distinct dissimilarities in proliferation, alkaline phosphatase activity, the expression of characteristic genes, and mineralization may aid to explain the differences in bone healing time observed in mandibular bone when compared to long bones of the extremities.

Substrate topography: A valuable in vitro tool, but a clinical red herring for in vivo tenogenesis

Publisher: Elsevier BV

Date: 11-2015

DOI: 10.1016/J.ACTBIO.2015.08.035

Abstract: Controlling the cell-substrate interactions at the bio-interface is becoming an inherent element in the design of implantable devices. Modulation of cellular adhesion in vitro, through topographical cues, is a well-documented process that offers control over subsequent cellular functions. However, it is still unclear whether surface topography can be translated into a clinically functional response in vivo at the tissue/device interface. Herein, we demonstrated that anisotropic substrates with a groove depth of ∼317nm and ∼1988nm promoted human tenocyte alignment parallel to the underlying topography in vitro. However, the rigid poly(lactic-co-glycolic acid) substrates used in this study upregulated the expression of chondrogenic and osteogenic genes, indicating possible tenocyte trans-differentiation. Of significant importance is that none of the topographies assessed (∼37nm, ∼317nm and ∼1988nm groove depth) induced extracellular matrix orientation parallel to the substrate orientation in a rat patellar tendon model. These data indicate that two-dimensional imprinting technologies are useful tools for in vitro cell phenotype maintenance, rather than for organised neotissue formation in vivo, should multifactorial approaches that consider both surface topography and substrate rigidity be established. Herein, we ventured to assess the influence of parallel groves, ranging from nano- to micro-level, on tenocytes response in vitro and on host response using a tendon and a subcutaneous model. In vitro analysis indicates that anisotropically ordered micro-scale grooves, as opposed to nano-scale grooves, maintain physiological cell morphology. The rather rigid PLGA substrates appeared to induce trans-differentiation towards chondrogenic and/or steogenic lineage, as evidence by TILDA gene analysis. In vivo data in both tendon and subcutaneous models indicate that none of the substrates induced bidirectional host cell and tissue growth. Collective, these observations indicate that two-dimensional imprinting technologies are useful tools for in vitro cell phenotype maintenance, rather than for directional neotissue formation, should multifactorial approaches that consider both surface topography and substrate rigidity be established.

Autologous vs. allogenic mesenchymal progenitor cells for the reconstruction of critical sized segmental tibial bone defects in aged sheep

Publisher: Elsevier BV

Date: 08-2013

DOI: 10.1016/J.ACTBIO.2013.04.035

Abstract: Mesenchymal progenitor cells (MPCs) represent an attractive cell population for bone tissue engineering. Their special immunological characteristics suggest that MPCs may be used in allogenic applications. The objective of this study was to compare the regenerative potential of autologous vs. allogenic MPCs in an ovine critical size segmental defect model. Ovine MPCs were isolated from bone marrow aspirates, expanded and cultured with osteogenic medium for 2weeks before implantation. Autologous and allogenic transplantation was performed using the cell-seeded scaffolds and unloaded scaffolds, while the application of autologous bone grafts served as a control group (n=6). Bone healing was assessed 12weeks after surgery by radiology, microcomputed tomography, biomechanical testing and histology. Radiology, biomechanical testing and histology revealed no significant differences in bone formation between the autologous and allogenic groups. Both cell groups showed more bone formation than the scaffold alone, whereas the biomechanical data showed no significant differences between the cell groups and the unloaded scaffolds. The results of the study suggest that scaffold-based bone tissue engineering using allogenic cells offers the potential for an off-the-shelf product. Thus the results of this study serve as an important baseline for translation of the assessed concepts into clinical applications.

Spatiotemporal delivery of bone morphogenetic protein enhances functional repair of segmental bone defects

Publisher: Elsevier BV

Date: 09-2011

DOI: 10.1016/J.BONE.2011.05.010

Colonization and Osteogenic Differentiation of Different Stem Cell Sources on Electrospun Nanofiber Meshes

Publisher: Mary Ann Liebert Inc

Date: 10-2010

DOI: 10.1089/TEN.TEA.2010.0004

Automated 3D Microphysiometry Facilitates High-Content and Highly Reproducible Oxygen Measurements within 3D Cell Culture Models

Publisher: American Chemical Society (ACS)

Date: 23-02-2021

DOI: 10.1021/ACSSENSORS.0C02551

A Medical-Grade Polycaprolactone and Tricalcium Phosphate Scaffold System With Corticoperiosteal Tissue Transfer for the Reconstruction of Acquired Calvarial Defects in Adults: Protocol for a Single-A

Publisher: JMIR Publications Inc.

Date: 13-10-2022

DOI: 10.2196/36111

Abstract: Large skull defects present a reconstructive challenge. Conventional cranioplasty options include autologous bone grafts, vascularized bone, metals, synthetic ceramics, and polymers. Autologous options are affected by resorption and residual contour deformities. Synthetic materials may be customized via digital planning and 3D printing, but they all carry a risk of implant exposure, failure, and infection, which increases when the defect is large. These complications can be a threat to life. Without reconstruction, patients with cranial defects may experience headaches and stigmatization. The protection of the brain necessitates lifelong helmet use, which is also stigmatizing. Our clinical trial will formally study a hybridized technique's capacity to reconstruct large calvarial defects. A hybridized technique that draws on the benefits of autologous and synthetic materials has been developed by the research team. This involves wrapping a biodegradable, ultrastructured, 3D-printed scaffold made of medical-grade polycaprolactone and tricalcium phosphate in a vascularized, autotransplanted periosteum to exploit the capacity of vascularized periostea to regenerate bone. In vitro, the scaffold system supports cell attachment, migration, and proliferation with slow but sustained degradation to permit host tissue regeneration and the replacement of the scaffold. The in vivo compatibility of this scaffold system is robust—the base material has been used clinically as a resorbable suture material for decades. The importance of scaffold vascularization, which is inextricably linked to bone regeneration, is underappreciated. A variety of methods have been described to address this, including scaffold prelamination and axial vascularization via arteriovenous loops and autotransplanted flaps. However, none of these directly promote bone regeneration. We expect to have results before the end of 2023. As of December 2020, we have enrolled 3 participants for the study. The regenerative matching axial vascularization technique may be an alternative method of reconstruction for large calvarial defects. It involves performing a vascularized free tissue transfer and using a bioresorbable, 3D-printed scaffold to promote and support bone regeneration (termed the regenerative matching axial vascularization technique). This technique may be used to reconstruct skull bone defects that were previously thought to be unreconstructable, reduce the risk of implant-related complications, and achieve consistent outcomes in cranioplasty. This must now be tested in prospective clinical trials. Australian New Zealand Clinical Trials Registry ACTRN12620001171909 rakccb3 DERR1-10.2196/36111

An Integrated Design, Material, and Fabrication Platform for Engineering Biomechanically and Biologically Functional Soft Tissues

Publisher: American Chemical Society (ACS)

Date: 23-08-2017

DOI: 10.1021/ACSAMI.7B08617

Abstract: We present a design rationale for stretchable soft network composites for engineering tissues that predominantly function under high tensile loads. The convergence of 3D-printed fibers selected from a design library and biodegradable interpenetrating polymer networks (IPNs) result in biomimetic tissue engineered constructs (bTECs) with fully tunable properties that can match specific tissue requirements. We present our technology platform using an exemplary soft network composite model that is characterized to be flexible, yet ∼125 times stronger (E = 3.19 MPa) and ∼100 times tougher (W

Osteogenic and Adipogenic Induction Potential of Human Periodontal Cells

Publisher: Wiley

Date: 03-2008

DOI: 10.1902/JOP.2008.070373

Abstract: Human periodontium contains different cell types that have various potential roles in hard and soft tissue regeneration. However, there is limited knowledge about how these erse cell populations contribute to the regenerative process. In this study, we investigated the surface marker difference between different periodontal cells (alveolar osteoblasts [AOs], periodontal ligament fibroblasts [PDLFs], and gingival fibroblasts [GFs]) and their differentiation potential toward osteogenic and adipogenic phenotypes. Periodontal cells (AOs, PDLFs, and GFs) from 14 subjects were isolated. The surface antigen expression pattern of cells was analyzed by cell flow cytometry, and the molecular and histologic characterizations under osteogenic and adipogenic inductions were monitored by reverse transcription-polymerase chain reaction, Western blot, and immunocytohistology. The cell phenotypes of AOs were verified by the high expressions of CD29 and CD49a, whereas PDLFs showed distinctively low levels of CD63 and CD73. Under adipogenic induction, limited AOs formed cube-shaped adipose-like cells, whereas PDLFs formed spindle-shaped adipose-like cells. All three cell types expressed baseline osteo-related genes. AOs demonstrated the highest osteogenic ability followed by PDLFs and GFs. Cells in alveolar bone and periodontal ligament contain osteogenic and adipogenic progenitors. These observations indicate a possible application for periodontium cells in hard or soft tissue regeneration.

A tissue-engineered humanized xenograft model of human breast cancer metastasis to bone

Publisher: The Company of Biologists

Date: 02-2014

DOI: 10.1242/DMM.014076

Abstract: The skeleton is a preferred homing site for breast cancer metastasis. To date, treatment options for patients with bone metastases are mostly palliative and the disease is still incurable. Indeed, key mechanisms involved in breast cancer osteotropism are still only partially understood due to the lack of suitable animal models to mimic metastasis of human tumor cells to a human bone microenvironment. In the presented study, we investigate the use of a human tissue-engineered bone construct to develop a humanized xenograft model of breast cancer-induced bone metastasis in a murine host. Primary human osteoblastic cell-seeded melt electrospun scaffolds in combination with recombinant human bone morphogenetic protein 7 were implanted subcutaneously in non-obese diabetic/severe combined immunodeficient mice. The tissue-engineered constructs led to the formation of a morphologically intact ‘organ’ bone incorporating a high amount of mineralized tissue, live osteocytes and bone marrow spaces. The newly formed bone was largely humanized, as indicated by the incorporation of human bone cells and human-derived matrix proteins. After intracardiac injection, the dissemination of luciferase-expressing human breast cancer cell lines to the humanized bone ossicles was detected by bioluminescent imaging. Histological analysis revealed the presence of metastases with clear osteolysis in the newly formed bone. Thus, human tissue-engineered bone constructs can be applied efficiently as a target tissue for human breast cancer cells injected into the blood circulation and replicate the osteolytic phenotype associated with breast cancer-induced bone lesions. In conclusion, we have developed an appropriate model for investigation of species-specific mechanisms of human breast cancer-related bone metastasis in vivo.

Evolutionary design of bone scaffolds with reference to material selection

Publisher: Wiley

Date: 06-2012

DOI: 10.1002/CNM.2487

Abstract: The favourable scaffold for bone tissue engineering should have desired characteristic features, such as adequate mechanical strength and three-dimensional open porosity, which guarantee a suitable environment for tissue regeneration. In fact, the design of such complex structures like bone scaffolds is a challenge for investigators. One of the aims is to achieve the best possible mechanical strength-degradation rate ratio. In this paper we attempt to use numerical modelling to evaluate material properties for designing bone tissue engineering scaffold fabricated via the fused deposition modelling technique. For our studies the standard genetic algorithm was used, which is an efficient method of discrete optimization. For the fused deposition modelling scaffold, each in idual strut is scrutinized for its role in the architecture and structural support it provides for the scaffold, and its contribution to the overall scaffold was studied. The goal of the study was to create a numerical tool that could help to acquire the desired behaviour of tissue engineered scaffolds and our results showed that this could be achieved efficiently by using different materials for in idual struts. To represent a great number of ways in which scaffold mechanical function loss could proceed, the exemplary set of different desirable scaffold stiffness loss function was chosen.

Response of Cells on Surface-Induced Nanopatterns:  Fibroblasts and Mesenchymal Progenitor Cells

Publisher: American Chemical Society (ACS)

Date: 28-03-2007

DOI: 10.1021/BM0611533

Abstract: Ultrathin films of a poly(styrene)-block-poly(2-vinylpyrindine) diblock copolymer (PS-b-P2VP) and poly(styrene)-block-poly(4-vinylpyrindine) diblock copolymer (PS-b-P4VP) were used to form surface-induced nanopattern (SINPAT) on mica. Surface interaction controlled microphase separation led to the formation of chemically heterogeneous surface nanopatterns on dry ultrathin films. Two distinct nanopatterned surfaces, namely, wormlike and dotlike patterns, were used to investigate the influence of topography in the nanometer range on cell adhesion, proliferation, and migration. Atomic force microscopy was used to confirm that SINPAT was stable under cell culture conditions. Fibroblasts and mesenchymal progenitor cells were cultured on the nanopatterned surfaces. Phase contrast and confocal laser microscopy showed that fibroblasts and mesenchymal progenitor cells preferred the densely spaced wormlike patterns. Atomic force microscopy showed that the cells remodelled the extracellular matrix differently as they migrate over the two distinctly different nanopatterns.

Engineering osteoblastic metastases to delineate the adaptive response of androgen-deprived prostate cancer in the bone metastatic microenvironment

Publisher: Springer Science and Business Media LLC

Date: 25-04-2019

DOI: 10.1038/S41413-019-0049-8

Abstract: While stromal interactions are essential in cancer adaptation to hormonal therapies, the effects of bone stroma and androgen deprivation on cancer progression in bone are poorly understood. Here, we tissue-engineered and validated an in vitro microtissue model of osteoblastic bone metastases, and used it to study the effects of androgen deprivation in this microenvironment. The model was established by culturing primary human osteoprogenitor cells on melt electrowritten polymer scaffolds, leading to a mineralized osteoblast-derived microtissue containing, in a 3D setting, viable osteoblastic cells, osteocytic cells, and appropriate expression of osteoblast/osteocyte-derived mRNA and proteins, and mineral content. Direct co-culture of androgen receptor-dependent/independent cell lines (LNCaP, C4-2B, and PC3) led cancer cells to display functional and molecular features as observed in vivo. Co-cultured cancer cells showed increased affinity to the microtissues, as a function of their bone metastatic potential. Co-cultures led to alkaline phosphatase and collagen-I upregulation and sclerostin downregulation, consistent with the clinical marker profile of osteoblastic bone metastases. LNCaP showed a significant adaptive response under androgen deprivation in the microtissues, with the notable appearance of neuroendocrine transdifferentiation features and increased expression of related markers (dopa decarboxylase, enolase 2). Androgen deprivation affected the biology of the metastatic microenvironment with stronger upregulation of androgen receptor, alkaline phosphatase, and dopa decarboxylase, as seen in the transition towards resistance. The unique microtissues engineered here represent a substantial asset to determine the involvement of the human bone microenvironment in prostate cancer progression and response to a therapeutic context in this microenvironment.

Preclinical Animal Models for Segmental Bone Defect Research and Tissue Engineering

Publisher: Springer Netherlands

Date: 23-11-2010

DOI: 10.1007/978-90-481-9075-1_36

Comprehensive Biomaterials

Publisher: Elsevier

Date: 2011

DOI: 10.1016/C2009-1-28384-5

Interactions between human osteoblasts and prostate cancer cells in a novel 3D in vitro model

Publisher: Informa UK Limited

Date: 07-2010

DOI: 10.4161/ORG.6.3.12041

Printomics: the high-throughput analysis of printing parameters applied to melt electrowriting

Publisher: IOP Publishing

Date: 24-01-2019

DOI: 10.1088/1758-5090/AAFC41

Abstract: Melt electrowriting (MEW) combines the fundamental principles of electrospinning, a fibre forming technology, and 3D printing. The process, however, is highly complex and the quality of the fabricated structures strongly depends on the interplay of key printing parameter settings including processing temperature, applied voltage, collection speed, and applied pressure. These parameters act in unison, comprising the principal forces on the electrified jet: pushing the viscous polymer out of the nozzle and mechanically and electrostatically dragging it for deposition towards the collector. Although previous studies interpreted the underlying mechanism of electrospinning with polymer melts in a direct writing mode, contemporary devices used in laboratory environments lack the capability to collect large data reproducibly. Yet, a validated large data set is a condition sine qua non to design an in-process control system which allows to computer control the complexity of the MEW process. For this reason, we engineered an advanced automated MEW system with monitoring capabilities to specifically generate large, reproducible data volumes which allows the interpretation of complex process parameters. Additionally, the design of an innovative real-time MEW monitoring system identifies the main effects of the system parameters on the geometry of the fibre flight path. This enables, for the first time, the establishment of a comprehensive correlation between the input parameters and the geometry of a MEW jet. The study verifies the most stable process parameters for the highly reproducible fabrication of a medical-grade poly(ε-caprolactone) fibres and demonstrates how Printomics can be performed for the high throughput analysis of processing parameters for MEW.

Combining electrospun scaffolds with electrosprayed hydrogels leads to three-dimensional cellularization of hybrid constructs

Publisher: American Chemical Society (ACS)

Date: 23-07-2008

DOI: 10.1021/BM800565U

Abstract: A common problem in the design of tissue engineered scaffolds using electrospun scaffolds is the poor cellular infiltration into the structure. To tackle this issue, three approaches to scaffold design using electrospinning were investigated: selective leaching of a water-soluble fiber phase (poly ethylene oxide (PEO) or gelatin), the use of micron-sized fibers as the scaffold, and a combination of micron-sized fibers with codeposition of a hyaluronic acid-derivative hydrogel, Heprasil. These designs were achieved by modifying a conventional electrospinning system with two charged capillaries and a rotating mandrel collector. Three types of scaffolds were fabricated: medical grade poly(epsilon-caprolactone)/collagen (mPCL/Col) cospun with PEO or gelatin, mPCL/Col meshes with micron-sized fibers, and mPCL/Col microfibers cosprayed with Heprasil. All three scaffold types supported attachment and proliferation of human fetal osteoblasts. However, selective leaching only marginally improved cellular infiltration when compared to meshes obtained by conventional electrospinning. Better cell penetration was seen in mPCL/Col microfibers, and this effect was more pronounced when Heprasil regions were present in the structure. Thus, such techniques could be further exploited for the design of cell permeable fibrous meshes for tissue engineering applications.

Heparan sulfate mediates the proliferation and differentiation of rat mesenchymal stem cells

Publisher: Mary Ann Liebert Inc

Date: 05-2009

DOI: 10.1089/SCD.2008.0157

Abstract: The growth and differentiation of mesenchymal stem cells (MSCs) is controlled by various growth factors, the activities of which can be modulated by heparan sulfates (HSs). We have previously noted the necessity of sulfated glycosaminoglycans for the fibroblast growth factor type 2 (FGF-2)-stimulated differentiation of osteoprogenitor cells. Here we show that exogenous application of HS to cultures of primary rat MSCs stimulates their proliferation, leading to increased expression of osteogenic markers and enhanced bone nodule formation. FGF-2 can also increase the proliferation, and osteogenic differentiation of rat bone marrow stem cells (rMSCs) when applied exogenously during their linear growth. However, as opposed to exogenous HS, the continuous use of FGF-2 during in vitro differentiation completely blocked rMSC mineralization. We show that the effects of both FGF-2 and HS are mediated through FGF receptor 1 (FGFR1) and that inhibition of signaling through this receptor arrests cell growth, resulting in the cells being unable to reach the critical density necessary to induce differentiation. Blocking FGFR1 signaling in postconfluent osteogenic cultures significantly increased calcium deposition. Taken together our data suggest that FGFR1 signaling plays an important role during osteogenic differentiation, first by stimulating cell growth that is closely followed by an inhibitory effect once the cells have reached confluence. It also confirms the importance of HS as a coreceptor for the signaling of endogenous FGF-2 and suggests that purified glycosaminoglycans may be attractive alternatives to growth factors for improved ex vivo growth and differentiation of MSCs.

Novel PCL-based honeycomb scaffolds as drug delivery systems for rhBMP-2

Publisher: Elsevier BV

Date: 06-2005

DOI: 10.1016/J.BIOMATERIALS.2004.09.052

Abstract: This study investigated a novel drug delivery system (DDS), consisting of polycaprolactone (PCL) or polycaprolactone 20% tricalcium phosphate (PCL-TCP) biodegradable scaffolds, fibrin Tisseel sealant and recombinant bone morphogenetic protein-2 (rhBMP-2) for bone regeneration. PCL and PCL-TCP-fibrin composites displayed a loading efficiency of 70% and 43%, respectively. Fluorescence and scanning electron microscopy revealed sparse clumps of rhBMP-2 particles, non-uniformly distributed on the rods' surface of PCL-fibrin composites. In contrast, in idual rhBMP-2 particles were evident and uniformly distributed on the rods' surface of the PCL-TCP-fibrin composites. PCL-fibrin composites loaded with 10 and 20 microg/ml rhBMP-2 demonstrated a triphasic release profile as quantified by an enzyme-linked immunosorbent assay (ELISA). This consisted of burst releases at 2 h, and days 7 and 16. A biphasic release profile was observed for PCL-TCP-fibrin composites loaded with 10 microg/ml rhBMP-2, consisting of burst releases at 2 h and day 14. PCL-TCP-fibrin composites loaded with 20 microg/ml rhBMP-2 showed a tri-phasic release profile, consisting of burst releases at 2 h, and days 10 and 21. We conclude that the addition of TCP caused a delay in rhBMP-2 release. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and alkaline phosphatase assay verified the stability and bioactivity of eluted rhBMP-2 at all time points.

Gelatin-methacrylamide hydrogels as potential biomaterials for fabrication of tissue-engineered cartilage constructs

Publisher: Wiley

Date: 18-02-2013

DOI: 10.1002/MABI.201200471

Abstract: Gelatin-methacrylamide (gelMA) hydrogels are shown to support chondrocyte viability and differentiation and give wide ranging mechanical properties depending on several cross-linking parameters. Polymer concentration, UV exposure time, and thermal gelation prior to UV exposure allow for control over hydrogel stiffness and swelling properties. GelMA solutions have a low viscosity at 37 °C, which is incompatible with most biofabrication approaches. However, incorporation of hyaluronic acid (HA) and/or co-deposition with thermoplastics allows gelMA to be used in biofabrication processes. These attributes may allow engineered constructs to match the natural functional variations in cartilage mechanical and geometrical properties.

Application of an X-ray microscopy technique to evaluate tissue-engineered bone-scaffold constructs

Publisher: Elsevier BV

Date: 05-2002

DOI: 10.1016/S0928-4931(02)00007-3

Comparison of the degradation of polycaprolactone and polycaprolactone–(β‐tricalcium phosphate) scaffolds in alkaline medium

Publisher: Wiley

Date: 20-03-2007

DOI: 10.1002/PI.2195

The use of basic fibroblast growth factor (bFGF) for enhancement of bone ingrowth into pyrolized bovine bone

Publisher: Elsevier BV

Date: 04-1995

DOI: 10.1016/S0901-5027(06)80098-6

Abstract: This pilot study aimed to investigate whether in vivo cultivation of bone in porous scaffolds can be enhanced by the use of growth factors. Four adult Göttingen minipigs received subperiosteal implantation of a block of pyrolized bovine bone on either side of the mandible. The blocks were covered with polylactic membrane. On one side, the implants were loaded with 240 micrograms of lyophilized basic fibroblast growth factor (bFGF). After 5 months, bone ingrowth was found throughout the whole block into the peripheral pore layers regardless of whether or not the scaffolds had been loaded with bFGF. Fluorescence labels likewise showed no significant differences in bone formation.

Assimilating cell sheets and hybrid scaffolds for dermal tissue engineering

Publisher: Wiley

Date: 16-08-2005

DOI: 10.1002/JBM.A.30454

Abstract: Cell sheets can be used to produce neo-tissue with mature extracellular matrix. However, extensive contraction of cell sheets remains a problem. We devised a technique to overcome this problem and applied it to tissue engineer a dermal construct. Human dermal fibroblasts were cultured with poly(lactic-co-glycolic acid)-collagen meshes and collagen-hyaluronic acid foams. Resulting cell sheets were folded over the scaffolds to form dermal constructs. Human keratinocytes were cultured on these dermal constructs to assess their ability to support bilayered skin regeneration. Dermal constructs produced with collagen-hyaluronic acid foams showed minimal contraction, while those with poly(lactic-co-glycolic acid)-collagen meshes curled up. Cell proliferation and metabolic activity profiles were characterized with PicoGreen and AlamarBlue assays, respectively. Fluorescent labeling showed high cell viability and F-actin expression within the constructs. Collagen deposition was detected by immunocytochemistry and electron microscopy. Transforming Growth Factor-alpha and beta1, Keratinocyte Growth Factor and Vascular Endothelial Growth Factor were produced at various stages of culture, measured by RT-PCR and ELISA. These results indicated that assimilating cell sheets with mechanically stable scaffolds could produce viable dermal-like constructs that do not contract. Repeated enzymatic treatment cycles for cell expansion is unnecessary, while the issue of poor cell seeding efficiency in scaffolds is eliminated.

A novel bioreactor system for biaxial mechanical loading enhances the properties of tissue-engineered human cartilage

Publisher: Springer Science and Business Media LLC

Date: 05-12-2017

DOI: 10.1038/S41598-017-16523-X

Abstract: The ex vivo engineering of autologous cartilage tissues has the potential to revolutionize the clinical management of joint disorders. Yet, high manufacturing costs and variable outcomes associated with tissue-engineered implants are still limiting their application. To improve clinical outcomes and facilitate a wider use of engineered tissues, automated bioreactor systems capable of enhancing and monitoring neotissues are required. Here, we developed an innovative system capable of applying precise uni- or biaxial mechanical stimulation to developing cartilage neotissues in a tightly controlled and automated fashion. The bioreactor allows for simple control over the loading parameters with a user-friendly graphical interface and is equipped with a load cell for monitoring tissue maturation. Applying our bioreactor, we demonstrate that human articular chondrocytes encapsulated in hydrogels composed of gelatin methacryloyl (GelMA) and hyaluronic acid methacrylate (HAMA) respond to uni- and biaxial mechanical stimulation by upregulation of hyaline cartilage-specific marker genes. We further demonstrate that intermittent biaxial mechanostimulation enhances accumulation of hyaline cartilage-specific extracellular matrix. Our study underlines the stimulatory effects of mechanical loading on the biosynthetic activity of human chondrocytes in engineered constructs and the need for easy-to-use, automated bioreactor systems in cartilage tissue engineering.

Robotic micro-assembly of scaffold/cell constructs with a shape memory alloy gripper

Publisher: IEEE

Date: 2002

DOI: 10.1109/ROBOT.2002.1014753

Engineering Anisotropic Muscle Tissue using Acoustic Cell Patterning

Publisher: Wiley

Date: 12-09-2018

DOI: 10.1002/ADMA.201802649

Rational Design of Mouse Models for Cancer Research

Publisher: Elsevier BV

Date: 03-2018

DOI: 10.1016/J.TIBTECH.2017.12.001

Abstract: The laboratory mouse is widely considered as a valid and affordable model organism to study human disease. Attempts to improve the relevance of murine models for the investigation of human pathologies led to the development of various genetically engineered, xenograft and humanized mouse models. Nevertheless, most preclinical studies in mice suffer from insufficient predictive value when compared with cancer biology and therapy response of human patients. We propose an innovative strategy to improve the predictive power of preclinical cancer models. Combining (i) genomic, tissue engineering and regenerative medicine approaches for rational design of mouse models with (ii) rapid prototyping and computational benchmarking against human clinical data will enable fast and nonbiased validation of newly generated models.

Phenotypic Characterization of Prostate Cancer LNCaP Cells Cultured within a Bioengineered Microenvironment

Publisher: Public Library of Science (PLoS)

Date: 05-09-2012

DOI: 10.1371/JOURNAL.PONE.0040217

Cell sourcing for bone tissue engineering: Amniotic fluid stem cells have a delayed, robust differentiation compared to mesenchymal stem cells

Publisher: Elsevier BV

Date: 07-2011

DOI: 10.1016/J.SCR.2011.03.001

In vivo tracking of segmental bone defect healing reveals that callus patterning is related to early mechanical stimuli

Publisher: European Cells and Materials

Date: 02-11-2012

DOI: 10.22203/ECM.V024A26

Abstract: This study addresses the hypothesis that callus formation, patterning, and mineralisation are impaired during the early phase of critical sized bone defect healing, and may relate to inter-fragmentary tissue strains within the bone defect area. Twenty four 12 week old Sprague Dawley rats were used for this study. They were ided into two groups defined by the femur bone defect size: (i) 1 mm resulting in normal healing (NH), and (ii) a large sized 5 mm defect resulting in critical healing (CH). Callus formation, patterning, and mineralisation kinetics in both groups were examined in the periosteal and osteotomy gap regions using a novel longitudinal study setup. Finite element analyses on µCT generated tomograms were used to determine inter-fragmentary tissue strain patterns and compared to callus formation and patterning over the course of time. Using a novel longitudinal study technique with µCT, in vivo tracking and computer simulation approaches, this study demonstrates that: (i) periosteal bone formation and patterning are significantly influenced by bone defect size as early as 2 weeks (ii) osteotomy gap callus formation and patterning are influenced by bone defect size, and adapt towards a non-union in critical cases by deviating into a medullary formation route as early as 2 weeks after osteotomy (iii) the new bone formation in the osteotomy gap enclosing the medullary cavity in the CH group is highly mineralised (iv) inter-fragmentary strain patterns predicted during the very early soft callus tissue phase (less than 2 weeks) are concurrent with callus formation and patterning at later stages. In conclusion, bone defect size influences early onset of critical healing patterns.

Fused deposition modeling of novel scaffold architectures for tissue engineering applications

Publisher: Elsevier BV

Date: 02-2002

DOI: 10.1016/S0142-9612(01)00232-0

Abstract: Fused deposition modeling, a rapid prototyping technology, was used to produce novel scaffolds with honeycomb-like pattern, fully interconnected channel network, and controllable porosity and channel size. A bioresorbable polymer poly(epsilon-caprolactone) (PCL) was developed as a filament modeling material to produce porous scaffolds, made of layers of directionally aligned microfilaments, using this computer-controlled extrusion and deposition process. The PCL scaffolds were produced with a range of channel size 160-700 microm, filament diameter 260-370 microm and porosity 48-77%, and regular geometrical honeycomb pores, depending on the processing parameters. The scaffolds of different porosity also exhibited a pattern of compressive stress-strain behavior characteristic of porous solids under such loading. The compressive stiffness ranged from 4 to 77 MPa, yield strength from 0.4 to 3.6 MPa and yield strain from 4% to 28%. Analysis of the measured data shows a high correlation between the scaffold porosity and the compressive properties based on a power-law relationship.

Cranioplasty after Trephination using a Novel Biodegradable Burr Hole Cover: Technical Case Report

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-2006

DOI: 10.1227/01.NEU.0000193533.54580.3F

Ultrafast Soft Actuators

Publisher: Research Square Platform LLC

Date: 22-03-2021

DOI: 10.21203/RS.3.RS-322598/V1

Abstract: The quest for an advanced soft robotic actuator technology that is fast and can execute a wide range of application-specific tasks at multiple length scales is still ongoing. Here, we demonstrate a new design strategy leveraging the concepts of miniaturisation and fibre-reinforcement to realize high-speed inflatable actuators exhibiting erse movements. To fabricate the designs, we employ a class of additive manufacturing technology called melt electrowriting. We demonstrate 3D printing of microfibre architectures on soft elastomers with precision at unprecedently small length scales, leading to miniaturised composite actuators with highly controlled deformation characteristics. We show that owing to their small dimensions and deterministically designed fibrous networks, our actuators require extremely low amounts of fluid to inflate. We demonstrate that actuators with a length of 10 to 15mm and an inner diameter 1mm can reach their full range of motion within ~ 20ms without exploiting snapping instabilities or material non-linearities. We display the speed of our actuators by building an ultrafast, soft flycatcher.

In vivo efficacy of bone‐marrow‐coated polycaprolactone scaffolds for the reconstruction of orbital defects in the pig

Publisher: Wiley

Date: 08-07-2003

DOI: 10.1002/JBM.B.10037

Abstract: Alloplastic materials offer a number of advantages over bone autografts in the reconstruction of craniofacial defects. These include: lack of donor site morbidity, unlimited quantities of available material, and the possibility to conform exactly to the defect. An ideal bioresorbable material would degrade slowly, and have osteoconductive properties to allow replacement and remodeling by osseous tissue. This is seldom observed, the materials instead being replaced by fibrous tissue. Polycaprolactone (PCL), an FDA-approved bioresorbable polymer, has several properties that might make it suitable for reconstruction of craniofacial defects. The technique of fused deposition modeling (FDM) allows for the fabrication of highly reproducible bioresorbable 3D scaffolds. The nature of the fully interconnected pore network might enhance vascular ingrowth and osteoconductive properties. It was hypothesized that coating the scaffolds in bone marrow might enhance bone formation due to the osteoinductive nature of the bone-marrow mesenchymal cells. This study aimed to test these hypotheses in the pig model. Defects measuring 2 x 2 cm were surgically created in each orbit of eight Yorkshire pigs. The orbits were ided into three groups: Group 1 (n=4), no reconstruction (control) Group 2 (n=6), reconstruction with no coated PCL scaffolds and Group 3 (n=6) reconstruction with bone-marrow-coated PCL scaffolds. The results were evaluated at 3 months by histological and histomorphometric analyses. The defects in Group 1 were covered with fibrous scar tissue. The shape of the reconstructed area was insufficient. The defects in Groups 2 and 3 were reconstructed correctly. In Group 2 the noncoated scaffolds showed 4.5% of new bone formation compared with 14.1% in Group 3, which is statistically significant (p<0.05). The entirely interconnected 3D polycaprolactone scaffold seems to be a promising material. It induces the bone ingrowth required for reconstructing craniofacial and orbital defects. Further long-term evaluations of these PCL scaffolds must be made in order to confirm these conclusions.

Fabrication and in vitro characterization of bioactive glass composite scaffolds for bone regeneration

Publisher: IOP Publishing

Date: 06-11-2013

DOI: 10.1088/1758-5082/5/4/045005

Abstract: Here we fabricate and characterize bioactive composite scaffolds for bone tissue engineering applications. 45S5 Bioglass® (45S5) or strontium-substituted bioactive glass (SrBG) were incorporated into polycaprolactone (PCL) and fabricated into 3D bioactive composite scaffolds utilizing additive manufacturing technology. We show that composite scaffolds (PCL/45S5 and PCL/SrBG) can be reproducibly manufactured with a scaffold morphology highly resembling that of PCL scaffolds. Additionally, micro-CT analysis reveals BG particles were homogeneously distributed throughout the scaffolds. Mechanical data suggested that PCL/45S5 and PCL/SrBG composite scaffolds have higher compressive Young's modulus compared to PCL scaffolds at similar porosity (∼75%). After 1 day in accelerated degradation conditions using 5M NaOH, PCL/SrBG, PCL/45S5 and PCL lost 48.6 ± 3.8%, 12.1 ± 1% and 1.6 ± 1% of the original mass, respectively. In vitro studies were conducted using MC3T3 cells under normal and osteogenic conditions. All scaffolds were shown to be non-cytotoxic, and supported cell attachment and proliferation. Our results also indicate that the inclusion of bioactive glass (BG) promotes precipitation of calcium phosphate on the scaffold surfaces which leads to earlier cell differentiation and matrix mineralization when compared to PCL scaffolds. However, as indicated by alkaline phosphatase activity, no significant difference in osteoblast differentiation was found between PCL/45S5 and PCL/SrBG scaffolds. These results suggest that PCL/45S5 and PCL/SrBG composite scaffolds show potential as next generation bone scaffolds.

The potential role of lycopene for the prevention and therapy of prostate cancer: From molecular mechanisms to clinical evidence

Publisher: MDPI AG

Date: 12-07-2013

DOI: 10.3390/IJMS140714620

Humanization of bone and bone marrow in an orthotopic site reveals new potential therapeutic targets in osteosarcoma

Publisher: Elsevier BV

Date: 07-2018

DOI: 10.1016/J.BIOMATERIALS.2018.04.030

Abstract: Existing preclinical murine models often fail to predict effects of anti-cancer drugs. In order to minimize interspecies-differences between murine hosts and human bone tumors of in vivo xenograft platforms, we tissue-engineered a novel orthotopic humanized bone model. Orthotopic humanized tissue engineered bone constructs (ohTEBC) were fabricated by 3D printing of medical-grade polycaprolactone scaffolds, which were seeded with human osteoblasts and embedded within polyethylene glycol-based hydrogels containing human umbilical vein endothelial cells (HUVECs). Constructs were then implanted at the femur of NOD-scid and NSG mice. NSG mice were then bone marrow transplanted with human CD34 After harvesting the femurs micro computed tomography and immunohistochemical staining showed an organ, which had all features of human bone. Around the original mouse femur new bone trabeculae have formed surrounded by a bone cortex. Staining for human specific (hs) collagen type-I (hs Col-I) showed human extracellular bone matrix production. The presence of nuclei staining positive for human nuclear mitotic apparatus protein 1 (hs NuMa) proved the osteocytes residing within the bone matrix were of human origin. Flow cytometry verified the presence of human hematopoietic cells. After injection of Luc-SAOS-2 cells a primary tumor and lung metastasis developed. After euthanization histological analysis showed pathognomic features of osteoblastic OS. Furthermore, the tumor utilized the previously implanted HUVECS for angiogenesis. Tumor marker expression was similar to human patients. Moreover, the recently discovered musculoskeletal gene C12orf29 was expressed in the most common subtypes of OS patient s les. OhTEBCs represent a suitable orthotopic microenvironment for humanized OS growth and offers a new translational direction, as the femur is the most common location of OS. The newly developed and validated preclinical model allows controlled and predictive marker studies of primary bone tumors and other bone malignancies.

3D printed Polycaprolactone scaffolds with dual macro-microporosity for applications in local delivery of antibiotics

Publisher: Elsevier BV

Date: 06-2018

DOI: 10.1016/J.MSEC.2018.02.008

Abstract: Advanced scaffolds used in tissue regenerating applications should be designed to address clinically relevant complications such as surgical site infection associated with surgical procedures. Recognizing that patient-specific scaffolds with local drug delivery capabilities are a promising approach, we combined 3D printing with traditional salt-leaching techniques to prepare a new type of scaffold with purposely designed macro- and micro-porosity. The dual macro/micro porous scaffolds of medical-grade polycaprolactone (mPCL) were characterized for their porosity, surface area, mechanical properties and degradation. The use of these scaffolds for local prophylactic release of Cefazolin to inhibit S. aureus growth was investigated as an ex le of drug delivery with this versatile platform. The introduction of microporosity and increased surface area allowed for loading of the scaffold using a simple drop-loading method of this heat-labile antibiotic and resulted in significant improvement in its release for up to 3 days. The Cefazolin released from scaffolds retained its bioactivity similar to that of fresh Cefazolin. There were no cytotoxic effects in vitro against 3 T3 fibroblasts at Cefazolin concentration of up to 100 μg/ml and no apparent effects on blood clot formation on the scaffolds in vitro. This study therefore presents a novel type of scaffolds with dual macro- and micro-porosity manufactured by a versatile method of 3D printing combined with salt-leaching. These scaffolds could be useful in tissue regeneration applications where it is desirable to prevent complications using local delivery of drugs.

Biologically Inspired Scaffolds for Heart Valve Tissue Engineering via Melt Electrowriting

Publisher: Wiley

Date: 06-05-2019

DOI: 10.1002/SMLL.201900873

Abstract: Heart valves are characterized to be highly flexible yet tough, and exhibit complex deformation characteristics such as nonlinearity, anisotropy, and viscoelasticity, which are, at best, only partially recapitulated in scaffolds for heart valve tissue engineering (HVTE). These biomechanical features are dictated by the structural properties and microarchitecture of the major tissue constituents, in particular collagen fibers. In this study, the unique capabilities of melt electrowriting (MEW) are exploited to create functional scaffolds with highly controlled fibrous microarchitectures mimicking the wavy nature of the collagen fibers and their load-dependent recruitment. Scaffolds with precisely-defined serpentine architectures reproduce the J-shaped strain stiffening, anisotropic and viscoelastic behavior of native heart valve leaflets, as demonstrated by quasistatic and dynamic mechanical characterization. They also support the growth of human vascular smooth muscle cells seeded both directly or encapsulated in fibrin, and promote the deposition of valvular extracellular matrix components. Finally, proof-of-principle MEW trileaflet valves display excellent acute hydrodynamic performance under aortic physiological conditions in a custom-made flow loop. The convergence of MEW and a biomimetic design approach enables a new paradigm for the manufacturing of scaffolds with highly controlled microarchitectures, biocompatibility, and stringent nonlinear and anisotropic mechanical properties required for HVTE.

Amniotic Fluid Stem Cells Produce Robust Mineral Deposits on Biodegradable Scaffolds

Publisher: Mary Ann Liebert Inc

Date: 10-2009

DOI: 10.1089/TEN.TEA.2008.0536

In vitro pre-vascularisation of tissue-engineered constructs A co-culture perspective

Publisher: Publiverse Online S.R.L

Date: 2014

DOI: 10.1186/2045-824X-6-13

Vitreous Cryopreservation of Nanofibrous Tissue-Engineered Constructs Generated Using Mesenchymal Stromal Cells

Publisher: Mary Ann Liebert Inc

Date: 03-2009

DOI: 10.1089/TEN.TEC.2008.0237

Abstract: Development of an effective preservation strategy to fulfill off-the-shelf availability of tissue-engineered constructs (TECs) is demanded for realizing their clinical potential. In this study, the feasibility of vitrification, ice-free cryopreservation, for precultured ready-to-use TECs was evaluated. To prepare the TECs, bone marrow-derived porcine mesenchymal stromal cells (MSCs) were seeded in polycaprolactone-gelatin nanofibrous scaffolds and cultured for 3 weeks before vitrification treatment. The vitrification strategy developed, which involved exposure of the TECs to low concentrations of cryoprotectants followed by a vitrification solution and sterile packaging in a pouch with its subsequent immersion directly into liquid nitrogen, was accomplished within 11min. Stepwise removal of cryoprotectants, after warming in a 38 degrees C water bath, enabled rapid restoration of the TECs. Vitrification did not impair microstructure of the scaffold or cell viability. No significant differences were found between the vitrified and control TECs in cellular metabolic activity and proliferation on matched days and in the trends during 5 weeks of continuous culture postvitrification. Osteogenic differentiation ability in vitrified and control groups was similar. In conclusion, we have developed a time- and cost-efficient cryopreservation method that maintains integrity of the TECs while preserving MSCs viability and metabolic activity, and their ability to differentiate.

A Tissue Engineering Solution for Segmental Defect Regeneration in Load-Bearing Long Bones

Publisher: American Association for the Advancement of Science (AAAS)

Date: 04-07-2012

DOI: 10.1126/SCITRANSLMED.3003720

Abstract: A polycaprolactone-tricalcium phosphate scaffold with recombinant human BMP-7 heals critical-sized bone defects in sheep.

3D-Printed Medical-Grade Polycaprolactone (mPCL) Scaffold for the Surgical Treatment of Vaginal Prolapse and Abdominal Hernias

Publisher: MDPI AG

Date: 24-10-2023

DOI: 10.3390/BIOENGINEERING10111242

Direct writing of chitosan scaffolds using a robotic system

Publisher: Emerald

Date: 04-2005

DOI: 10.1108/13552540510589458

Abstract: This paper aims to present a novel rapid prototyping (RP) fabrication methods and preliminary characterization for chitosan scaffolds. A desktop rapid prototyping robot dispensing (RPBOD) system has been developed to fabricate scaffolds for tissue engineering (TE) applications. The system is a computer‐controlled four‐axis machine with a multiple‐dispenser head. Neutralization of the acetic acid by the sodium hydroxide results in a precipitate to form a gel‐like chitosan strand. The scaffold properties were characterized by scanning electron microscopy, porosity calculation and compression test. An ex le of fabrication of a freeform hydrogel scaffold is demonstrated. The required geometric data for the freeform scaffold were obtained from CT‐scan images and the dispensing path control data were converted form its volume model. The applications of the scaffolds are discussed based on its potential for TE. It is shown that the RPBOD system can be interfaced with imaging techniques and computational modeling to produce scaffolds which can be customized in overall size and shape allowing tissue‐engineered grafts to be tailored to specific applications or even for in idual patients. Important challenges for further research are the incorporation of growth factors, as well as cell seeding into the 3D dispensing plotting materials. Improvements regarding the mechanical properties of the scaffolds are also necessary. One of the important aspects of TE is the design scaffolds. For customized TE, it is essential to be able to fabricate 3D scaffolds of various geometric shapes, in order to repair tissue defects. RP or solid free‐form fabrication techniques hold great promise for designing 3D customized scaffolds yet traditional cell‐seeding techniques may not provide enough cell mass for larger constructs. This paper presents a novel attempt to fabricate 3D scaffolds, using hydrogels which in the future can be combined with cells.

Flow modeling in a novel non‐perfusion conical bioreactor

Publisher: Wiley

Date: 10-01-2007

DOI: 10.1002/BIT.21327

Abstract: We have developed a bioreactor vessel design which has the advantages of simplicity and ease of assembly and disassembly, and with the appropriately determined flow rate, even allows for a scaffold to be suspended freely regardless of its weight. This article reports our experimental and numerical investigations to evaluate the performance of a newly developed non-perfusion conical bioreactor by visualizing the flow through scaffolds with 45 degrees and 90 degrees fiber lay down patterns. The experiments were conducted at the Reynolds numbers (Re) 121, 170, and 218 based on the local velocity and width of scaffolds. The flow fields were captured using short-time exposures of 60 microm particles suspended in the bioreactor and illuminated using a thin laser sheet. The effects of scaffold fiber lay down pattern and Reynolds number were obtained and correspondingly compared to results obtained from a computational fluid dynamics (CFD) software package. The objectives of this article are twofold: to investigate the hypothesis that there may be an insufficient exchange of medium within the interior of the scaffold when using our non-perfusion bioreactor, and second, to compare the flows within and around scaffolds of 45 degrees and 90 degrees fiber lay down patterns. Scaffold porosity was also found to influence flow patterns. It was therefore shown that fluidic transport could be achieved within scaffolds with our bioreactor design, being a non-perfusion vessel. Fluid velocities were generally same of the same or one order lower in magnitude as compared to the inlet flow velocity. Additionally, the 90 degrees fiber lay down pattern scaffold was found to allow for slightly higher fluid velocities within, as compared to the 45 degrees fiber lay down pattern scaffold. This was due to the architecture and pore arrangement of the 90 degrees fiber lay down pattern scaffold, which allows for fluid to flow directly through (channel-like flow).

Contributors

Publisher: Elsevier

Date: 2023

DOI: 10.1016/B978-0-12-824459-3.01002-7

Paracrine interactions between LNCaP prostate cancer cells and bioengineered bone in 3D in vitro culture reflect molecular changes during bone metastasis

Publisher: Elsevier BV

Date: 06-2014

DOI: 10.1016/J.BONE.2014.02.001

Abstract: As microenvironmental factors such as three-dimensionality and cell-matrix interactions are increasingly being acknowledged by cancer biologists, more complex 3D in vitro models are being developed to study tumorigenesis and cancer progression. To better understand the pathophysiology of bone metastasis, we have established and validated a 3D indirect co-culture model to investigate the paracrine interactions between prostate cancer (PCa) cells and human osteoblasts. Co-culture of the human PCa, LNCaP cells embedded within polyethylene glycol hydrogels with human osteoblasts in the form of a tissue engineered bone construct (TEB), resulted in reduced proliferation of LNCaP cells. LNCaP cells in both monoculture and co-culture were responsive to the androgen analog, R1881, as indicated by an increase in the expression (mRNA and/or protein induction) of androgen-regulated genes including prostate specific antigen and fatty acid synthase. Microarray gene expression analysis further revealed an up-regulation of bone markers and other genes associated with skeletal and vasculature development and a significant activation of transforming growth factor β1 downstream genes in LNCaP cells after co-culture with TEB. LNCaP cells co-cultured with TEB also unexpectedly showed similar changes in classical androgen-responsive genes under androgen-deprived conditions not seen in LNCaP monocultures. The molecular changes of LNCaP cells after co-culturing with TEBs suggest that osteoblasts exert a paracrine effect that may promote osteomimicry and modulate the expression of androgen-responsive genes in LNCaP cells. Taken together, we have presented a novel 3D in vitro model that allows the study of cellular and molecular changes occurring in PCa cells and osteoblasts that are relevant to metastatic colonization of bone. This unique in vitro model could also facilitate cancer biologists to dissect specific biological hypotheses via extensive genomic or proteomic assessments to further our understanding of the PCa-bone crosstalk.

ACCESS - IV. The quenching of star formation in a cluster population of dusty S0s

Publisher: Oxford University Press (OUP)

Date: 09-09-2011

DOI: 10.1111/J.1365-2966.2011.19445.X

Convergence of 3D printed biomimetic wound dressings and adult stem cell therapy

Publisher: Elsevier BV

Date: 2021

DOI: 10.1016/J.BIOMATERIALS.2020.120558

Can tissue engineering concepts advance tumor biology research?

Publisher: Elsevier BV

Date: 03-2010

DOI: 10.1016/J.TIBTECH.2009.12.001

Abstract: Advances in tissue engineering have traditionally led to the design of scaffold- or matrix-based culture systems that better reflect the biological, physical and biochemical environment of the natural extracellular matrix. Although their clinical applications in regenerative medicine tend to receive most of the attention, it is obvious that other areas of biomedical research could be well served by the powerful tools that have already been developed in tissue engineering. In this article, we review the recent literature to demonstrate how tissue engineering platforms can enhance in vitro and in vivo models of tumorigenesis and thus hold great promise to contribute to future cancer research.

Effect of plasma immersion ion implantation on polycaprolactone with various molecular weights and crystallinity

Publisher: Springer Science and Business Media LLC

Date: 14-12-2017

DOI: 10.1007/S10856-017-6009-1

Abstract: Polycaprolactone with five different molecular weights was spin-coated on silicon wafers and plasma immersion ion implanted (PIII) with ion fluence in the range 5 × 10

Near-field effects on coherent anti-Stokes Raman scattering microscopy imaging

Publisher: Optica Publishing Group

Date: 2007

DOI: 10.1364/OE.15.004118

Abstract: We introduce a numerical method, the finite-difference time-domain (FDTD) method, to study the near-field effects on coherent anti-Stokes Raman Scattering (CARS) microscopy on nanoparticles. Changes of the induced nonlinear polarization, scattering patterns, and polarization properties against different diameters of spherical nanoparticles are calculated and discussed in details. The results show that due to near-field effects, the induced nonlinear polarization is significantly enhanced at the water-particle interface, with 1.5-fold increase in intensity compared to that inside the particles, and the near-field enhancement increases with decreasing diameters of nanoparticles. The enhanced scattering dominates over the scattering contribution from the particles when the nanoparticle size decreases down to the scale of less than a half wavelength of excitation light. Further studies show that near-field effects make the induced perpendicular polarization of CARS signals being strictly confined within the nanoparticles and the particle-water interface, and this perpendicular polarization component could contribute approximately 20% to the backward scattering. The ratio values of the perpendicular polarization component to the total CARS signals from nanoparticles sizing from 75 nm to 300 nm in backward scattering are approximately 3 to 5 times higher than those in forward scattering. Therefore, near-field effects can play an important role in CARS imaging. Employing the perpendicular polarization component of CARS signals can significantly improve the contrast of CARS images, and be particularly useful for revealing the fine structures of bio-materials with nano-scale resolutions.

Scaffold Design and Fabrication

Publisher: Elsevier

Date: 2014

DOI: 10.1016/B978-0-12-420145-3.00010-9

Composite electrospun scaffolds for engineering tubular bone grafts

Publisher: Mary Ann Liebert Inc

Date: 12-2009

DOI: 10.1089/TEN.TEA.2009.0186

Does seeding density affect in vitro mineral nodules formation in novel composite scaffolds?

Publisher: Wiley

Date: 20-04-2006

DOI: 10.1002/JBM.A.30685

Abstract: This study investigated the human alveolar osteoblasts (AOs) proliferation and extracellular matrix formation at seeding density of 0.05, 0.1, 0.2, 0.4, and 0.8 million (M) per 3x4x4 mm3 on medical grade polycaprolactone-tricalcium phosphate (mPCL-TCP) scaffolds designed for bone regeneration. Over 80-90% of the initial seeded cells were retained in the scaffolds after 24 h. AOs bridged over pores at density of 0.2M/scaffold and below, but formed cell balls at density of 0.4M/scaffold and above. At seeding density of 0.2M and below, cell proliferation increased with time having DNA content peaked to 1600 ng/scaffold at day 21 and 28, respectively, whereas at 0.4 and 0.8M, the corresponding DNA content decreased to 1600 ng in 28 days. At day 7, higher alkaline phosphatase (ALP) activity and higher osteocalcin (OCN) secretion were detected at 0.2M/scaffold and below. After 28 days, multilayered cell-sheet formation and collagen fibers were observed at all densities. ALP and OCN in matrix and mineral nodules were found mainly at the border of AOs-scaffold construct. These findings demonstrated that the density of 0.2M and below per 3 x 4 x 4 mm(3) scaffold resulted in better cell proliferation and extracellular matrix synthesis, potentially resulting in better mineralized tissue formation.

Eyes on 3D‐Current 3D Biomimetic Disease Concept Models and Potential Applications in Age‐Related Macular Degeneration

Publisher: Wiley

Date: 28-01-2013

DOI: 10.1002/ADHM.201200445

Abstract: Three-dimensional cellular models that mimic disease are being increasingly investigated and have opened an exciting new research area into understanding pathomechanisms. The advantage of 3D in vitro disease models is that they allow systematic and in depth studies of physiological and pathophysiological processes with less costs and ethical concerns that have arisen with animal models. The purpose of the 30 approach is to allow crosstalk between cells and microenvironment, and with cues from the microenvironment,cells can assemble their niche similar to in vivo conditions. The use of 3D models for mimicking disease processes such as cancer, osteoarthritis etc., Is only emerging and allows multidisciplinary teams consisting of tissue engineers, biologist biomaterial scientists and clinicians to work closely together. While in vitro systems require rigorous testing before they can be considered as replicates of the in vivo model, major steps have been made,suggesting that they will become powerful tools for studying physiological and pathophysiological processes. This paper aims to summarize some of the existing 3D models and proposes a novel 3D model of the eye structures that are involved in the most common cause of blindness in the Western World,namely age-related macular degeneration (AMD).

Vascularised bone transfer: History, blood supply and contemporary problems

Publisher: Elsevier BV

Date: 2017

DOI: 10.1016/J.BJPS.2016.07.012

Abstract: Since the description of the free fibula flap by Taylor in 1975, many flaps composed of bone have been described. This review documents the history of vascularised bone transfer and reflects on the current understanding of blood supply in an effort to define all clinically described osseous flaps. A structured review of MEDLINE and Google Scholar was performed to identify all clinically described bone flaps in humans. Data regarding patterns of vascularity were collected where available from the anatomical literature. Vascularised bone transfer has evolved stepwise in concert with advances in reconstructive surgery techniques. This began with local flaps of the craniofacial skeleton in the late 19th century, followed by regional flaps such as the fibula flap for tibial reconstruction in the early 20th century. Prelaminated and pedicled myo-osseous flaps predominated until the advent of microsurgery and free tissue transfer in the 1960s and 1970s. Fifty-two different bone flaps were identified from 27 different bones. These flaps can be broadly classified into three types to reflect the pedicle: nutrient vessel (NV), penetrating periosteal vessel (PPV) and non-penetrating periosteal vessel (NPPV). NPPVs can be further classified according to the anatomical structure that serves as a conduit for the pedicle which may be direct-periosteal, musculoperiosteal or fascioperiosteal. The blood supply to bone is well described and is important to the reconstructive surgeon in the design of reliable vascularised bone suitable for transfer into defects requiring osseous replacement. Further study in this field could be directed at the implications of the pattern of bone flap vascularity on reconstructive outcomes, the changes in bone vascularity after osteotomy and the existence of "true" and "choke" anastomoses in cortical bone.

Development and characterisation of a new bioink for additive tissue manufacturing

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C3TB21280G

Bacterial comparison of preoperative rinsing and swabbing for oral surgery using 0.2% chlorhexidine

Publisher: Wiley

Date: 22-05-2015

DOI: 10.1111/JICD.12099

Abstract: The aim of the present study was to compare bacterial load using preoperative rinsing and swabbing techniques for oral surgery with 0.2% chlorhexidine (CHX). Participants were healthy volunteers undergoing a general anesthetic for the removal of teeth. Participants were randomly allocated to receive 15 mL of 0.2% CHX for 60 s as either a rinse or have their mouths swabbed. Plaque s les were aseptically collected pre- and post-rinsing from the same sites in all patients (the distal surface of all second molar teeth). Patients in the swab group had similar bacteria counts before and after the application of CHX (143.4 vs 138.5 colonies, P = 1.000). After rinsing with CHX, there was an eightfold reduction of bacterial load (71 vs 8.8 colonies, P < 0.001). The present study demonstrates that the use of CHX as an antimicrobial agent is effective in reducing the overall number of bacterial colonies in the oral cavity. Rinsing is a more effective method of doing this.

Preliminary study on the adhesion and proliferation of human osteoblasts on starch-based scaffolds

Publisher: No publisher found

Date: 2002

DOI: 10.1016/S0928-4931(02)00009-7

Intravital microscopy of osteolytic progression and therapy response of cancer lesions in the bone

Publisher: American Association for the Advancement of Science (AAAS)

Date: 08-2018

DOI: 10.1126/SCITRANSLMED.AAO5726

Abstract: A skin window enables noninvasive, longitudinal monitoring of cancer growth and therapy response in tissue-engineered bone in mice.

Biomaterial science meets computational biology

Publisher: Springer Science and Business Media LLC

Date: 18-04-2015

DOI: 10.1007/S10856-015-5518-Z

Abstract: There is a pressing need for a predictive tool capable of revealing a holistic understanding of fundamental elements in the normal and pathological cell physiology of organoids in order to decipher the mechanoresponse of cells. Therefore, the integration of a systems bioengineering approach into a validated mathematical model is necessary to develop a new simulation tool. This tool can only be innovative by combining biomaterials science with computational biology. Systems-level and multi-scale experimental data are incorporated into a single framework, thus representing both single cells and collective cell behaviour. Such a computational platform needs to be validated in order to discover key mechano-biological factors associated with cell-cell and cell-niche interactions.

Repair of Large Articular Osteochondral Defects Using Hybrid Scaffolds and Bone Marrow-Derived Mesenchymal Stem Cells in a Rabbit Model

Publisher: Mary Ann Liebert Inc

Date: 06-2006

DOI: 10.1089/TEN.2006.12.1539

Abstract: In order to evaluate the repair potential in large osteochondral defects on high load-bearing sites, a hybrid scaffold system was made of three-dimensional porous Polycaprolactone (PCL) scaffold for the cartilage and tricalcium phosphate-reinforced PCL for the bone portion. Osteochondral defects of 4-mm diameter x 5.5-mm depth were created in the medial femoral condyle of adult New Zealand White rabbits. The defects were treated with hybrid scaffolds without cells (control group) or seeded with allogenic bone marrow-derived mesenchymal stem cells (BMSC) in each part (experimental group) by press-fit implantation. Implanted cells were tracked using Adeno-LacZ labeling. Repair tissues were evaluated at 3 and 6 months after implantation. Overall, the experimental group showed superior repair results as compared to the control group using gross examination, qualitative and quantitative histology, and biomechanical assessment. With BMSC implantation, the hybrid scaffolds provided sufficient support to new osteochondral tissues formation. The bone regeneration was consistently good from 3 to 6 months with firm integration to the host tissue. Cartilage layer resurfacing was more complicated. All of the s les showed cartilage tissues mixed with PCL scaffold filaments at 3 months. Histology at 6 months revealed some degradation phenomenon in several s les whereas others had a good appearance however, the Young's moduli from the experimental group (0.72 MPa) approached that of normal cartilage (0.81 MPa). In vivo viability of implanted cells was demonstrated by the retention for 6 weeks in the scaffolds. This investigation showed that PCL-based hybrid scaffolds with BMSC may be an alternative treatment for large osteochondral defects in high-loading sites.

Microenvironment engineering of osteoblastic bone metastases reveals osteomimicry of patient-derived prostate cancer xenografts

Publisher: Elsevier BV

Date: 11-2019

DOI: 10.1016/J.BIOMATERIALS.2019.119402

Abstract: Representative in vitro models that mimic the native bone tumor microenvironment are warranted to support the development of more successful treatments for bone metastases. Here, we have developed a primary cell 3D model consisting of a human osteoblast-derived tissue-engineered construct (hOTEC) indirectly co-cultured with patient-derived prostate cancer xenografts (PDXs), in order to study molecular interactions in a patient-derived microenvironment context. The engineered biomimetic microenvironment had high mineralization and embedded osteocytes, and supported a high degree of cancer cell osteomimicry at the gene, protein and mineralization levels when co-cultured with prostate cancer PDXs from a lymph node metastasis (LuCaP35) and bone metastasis (BM18) from patients with primary prostate cancer. This fully patient-derived model is a promising tool for the assessment of new molecular mechanisms and as a personalized pre-clinical platform for therapy testing for patients with prostate cancer bone metastases.

Cancer-associated fibroblasts of the prostate promote a compliant and more invasive phenotype in benign prostate epithelial cells

Publisher: Elsevier BV

Date: 09-2020

DOI: 10.1016/J.MTBIO.2020.100073

Bone Repair and Adult Stem Cells

Publisher: WORLD SCIENTIFIC

Date: 07-2005

DOI: 10.1142/9789812569370_0021

Abstracts from the Spectra 2018 Symposium Part 7: Environment and Bio-Science

Publisher: MIT Press - Journals

Date: 05-10-2021

DOI: 10.1162/LEON_A_02155

Erratum to: Biological performance of a polycaprolactone-based scaffold plus recombinant human morphogenetic protein-2 (rhBMP-2) in an ovine thoracic interbody fusion model

Publisher: Springer Science and Business Media LLC

Date: 07-02-2015

DOI: 10.1007/S00586-015-3780-X

Customised osteotomy guides and endoprosthetic reconstruction for periacetabular tumours

Publisher: Springer Science and Business Media LLC

Date: 23-03-2014

DOI: 10.1007/S00264-014-2314-1

Manufacturing meets biofabrication: Part 1

Publisher: Walter de Gruyter GmbH

Date: 2014

DOI: 10.1515/BNM-2014-0012

Melt electrospinning of polycaprolactone and its blends with poly(ethylene glycol)

Publisher: Wiley

Date: 19-10-2010

DOI: 10.1002/PI.2954

Convergence of Scaffold-Guided Bone Reconstruction and Surgical Vascularization Strategies—A Quest for Regenerative Matching Axial Vascularization

Publisher: Frontiers Media SA

Date: 10-01-2020

DOI: 10.3389/FBIOE.2019.00448

Induced pluripotent stem cells

Publisher: SAGE Publications

Date: 18-08-2015

DOI: 10.1177/0022034515599769

Abstract: Induced pluripotent stem cells (iPSCs) are the newest member of a growing list of stem cell populations that hold great potential for use in cell-based treatment approaches in the dental field. This review summarizes the dental tissues that have successfully been utilized to generate iPSC lines, as well as the potential uses of iPSCs for tissue regeneration in different dental applications. While iPSCs display great promise in a number of dental applications, there are safety concerns with these cells that need to be addressed before they can be used in clinical settings. This review outlines some of the apprehensions to the use of iPSCs clinically, and it details approaches that are being employed to ensure the safety and efficacy of these cells. One of the major approaches being investigated is the differentiation of iPSCs prior to use in patients. iPSCs have successfully been differentiated into a wide range of cells and tissue types. This review focuses on 2 differentiation approaches—the differentiation of iPSCs into mesenchymal stem cells and the differentiation of iPSCs into osteoprogenitor cells. Both these resulting populations of cells are particularly relevant to the dental field.

Scaffold and implant design: Considerations relating to characterization of biodegradablity and bioresorbability

Publisher: Elsevier

Date: 2008

DOI: 10.1533/9781845695033.5.319

Characterization of a novel bioactive poly[(lactic acid)‐co‐(glycolic acid)] and collagen hybrid matrix for dermal regeneration

Publisher: Wiley

Date: 15-06-2005

DOI: 10.1002/PI.1868

Melt Electrospinning

Publisher: Wiley

Date: 15-11-2010

DOI: 10.1002/ASIA.201000436

Abstract: Melt electrospinning is relatively under-investigated compared to solution electrospinning but provides opportunities in numerous areas, in which solvent accumulation or toxicity are a concern. These applications are erse, and provide a broad set of challenges to researchers involved in electrospinning. In this context, melt electrospinning provides an alternative approach that bypasses some challenges to solution electrospinning, while bringing new issues to the forefront, such as the thermal stability of polymers. This Focus Review describes the literature on melt electrospinning, as well as highlighting areas where both melt and solution are combined, and potentially merge together in the future.

3D printed lattices as an activation and expansion platform for T cell therapy

Publisher: Elsevier BV

Date: 09-2017

DOI: 10.1016/J.BIOMATERIALS.2017.05.009

Abstract: One of the most significant hurdles to the affordable, accessible delivery of cell therapy is the cost and difficulty of expanding cells to clinically relevant numbers. Immunotherapy to prevent autoimmune disease, tolerate organ transplants or target cancer critically relies on the expansion of specialized T cell populations. We have designed 3D-printed cell culture lattices with highly organized micron-scale architectures, functionalized via plasma polymerization to bind monoclonal antibodies that trigger cell proliferation. This 3D technology platform facilitate the expansion of therapeutic human T cell subsets, including regulatory, effector, and cytotoxic T cells while maintaining the correct phenotype. Lentiviral gene delivery to T cells is enhanced in the presence of the lattices. Incorporation of the lattice format into existing cell culture vessels such as the G-Rex system is feasible. This cell expansion platform is user-friendly and expedites cell recovery and scale-up, making it ideal for translating T cell therapies from bench to bedside.

Design and Fabrication of Tubular Scaffolds via Direct Writing in a Melt Electrospinning Mode

Publisher: American Vacuum Society

Date: 09-02-2012

DOI: 10.1007/S13758-011-0013-7

Abstract: Flexible tubular structures fabricated from solution electrospun fibers are finding increasing use in tissue engineering applications. However it is difficult to control the deposition of fibers due to the chaotic nature of the solution electrospinning jet. By using non-conductive polymer melts instead of polymer solutions the path and collection of the fiber becomes predictable. In this work we demonstrate the melt electrospinning of polycaprolactone in a direct writing mode onto a rotating cylinder. This allows the design and fabrication of tubes using 20 μm diameter fibers with controllable micropatterns and mechanical properties. A key design parameter is the fiber winding angle, where it allows control over scaffold pore morphology (e.g. size, shape, number and porosity). Furthermore, the establishment of a finite element model as a predictive design tool is validated against mechanical testing results of melt electrospun tubes to show that a lesser winding angle provides improved mechanical response to uniaxial tension and compression. In addition, we show that melt electrospun tubes support the growth of three different cell types in vitro and are therefore promising scaffolds for tissue engineering applications.

Nipple Reconstruction: A Regenerative Medicine Approach Using 3D-Printed Tissue Scaffolds

Publisher: Mary Ann Liebert Inc

Date: 04-2019

DOI: 10.1089/TEN.TEB.2018.0253

Correction: Humanized bone facilitates prostate cancer metastasis and recapitulates therapeutic effects of Zoledronic acid in vivo

Publisher: Springer Science and Business Media LLC

Date: 03-04-2020

DOI: 10.1038/S41413-020-0092-5

Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Ultrafast, miniature soft actuators

Publisher: IOP Publishing

Date: 11-2021

DOI: 10.1088/2399-7532/AC2FAF

Three-Dimensional Bioprinting for Regenerative Dentistry and Craniofacial Tissue Engineering

Publisher: SAGE Publications

Date: 29-06-2015

DOI: 10.1177/0022034515588885

Abstract: Craniofacial tissues are organized with complex 3-dimensional (3D) architectures. Mimicking such 3D complexity and the multicellular interactions naturally occurring in craniofacial structures represents one of the greatest challenges in regenerative dentistry. Three-dimensional bioprinting of tissues and biological structures has been proposed as a promising alternative to address some of these key challenges. It enables precise manufacture of various biomaterials with complex 3D architectures, while being compatible with multiple cell sources and being customizable to patient-specific needs. This review describes different 3D bioprinting methods and summarizes how different classes of biomaterials (polymer hydrogels, ceramics, composites, and cell aggregates) may be used for 3D biomanufacturing of scaffolds, as well as craniofacial tissue analogs. While the fabrication of scaffolds upon which cells attach, migrate, and proliferate is already in use, printing of all the components that form a tissue (living cells and matrix materials together) to produce tissue constructs is still in its early stages. In summary, this review seeks to highlight some of the key advantages of 3D bioprinting technology for the regeneration of craniofacial structures. Additionally, it stimulates progress on the development of strategies that will promote the translation of craniofacial tissue engineering from the laboratory bench to the chair side.

A biphasic scaffold design combined with cell sheet technology for simultaneous regeneration of alveolar bone/periodontal ligament complex

Publisher: Elsevier BV

Date: 08-2012

DOI: 10.1016/J.BIOMATERIALS.2012.04.038

Abstract: This study describes the design of a biphasic scaffold composed of a Fused Deposition Modeling scaffold (bone compartment) and an electrospun membrane (periodontal compartment) for periodontal regeneration. In order to achieve simultaneous alveolar bone and periodontal ligament regeneration a cell-based strategy was carried out by combining osteoblast culture in the bone compartment and placement of multiple periodontal ligament (PDL) cell sheets on the electrospun membrane. In vitro data showed that the osteoblasts formed mineralized matrix in the bone compartment after 21 days in culture and that the PDL cell sheet harvesting did not induce significant cell death. The cell-seeded biphasic scaffolds were placed onto a dentin block and implanted for 8 weeks in an athymic rat subcutaneous model. The scaffolds were analyzed by μCT, immunohistochemistry and histology. In the bone compartment, a more intense ALP staining was obtained following seeding with osteoblasts, confirming the μCT results which showed higher mineralization density for these scaffolds. A thin mineralized cementum-like tissue was deposited on the dentin surface for the scaffolds incorporating the multiple PDL cell sheets, as observed by H&E and Azan staining. These scaffolds also demonstrated better attachment onto the dentin surface compared to no attachment when no cell sheets were used. In addition, immunohistochemistry revealed the presence of CEMP1 protein at the interface with the dentine. These results demonstrated that the combination of multiple PDL cell sheets and a biphasic scaffold allows the simultaneous delivery of the cells necessary for in vivo regeneration of alveolar bone, periodontal ligament and cementum.

GelMA and Biomimetic Culture Allow the Engineering of Mineralized, Adipose, and Tumor Tissue Human Microenvironments for the Study of Advanced Prostate Cancer In Vitro and In Vivo

Publisher: Wiley

Date: 21-02-2023

DOI: 10.1002/ADHM.202201701

Abstract: Increasing evidence shows bone marrow (BM)‐adipocytes as a potentially important contributor in prostate cancer (PCa) bone metastases. However, a lack of relevant models has prevented the full understanding of the effects of human BM‐adipocytes in this microenvironment. It is hypothesized that the combination of tunable gelatin methacrylamide (GelMA)‐based hydrogels with the biomimetic culture of human cells would offer a versatile 3D platform to engineer human bone tumor microenvironments containing BM‐adipocytes. Human osteoprogenitors, adipocytes, and PCa cells are in idually cultured in vitro in GelMA hydrogels, leading to mineralized, adipose, and PCa tumor 3D microtissues, respectively. Osteoblast mineralization and tumor spheroid formation are tailored by hydrogel stiffness with lower stiffnesses correlating with increased mineralization and tumor spheroid size. Upon coculture with tumor cells, BM‐adipocytes undergo morphological changes and delipidation, suggesting reciprocal interactions between the cell types. When brought in vivo, the mineralized and adipose microtissues successfully form a humanized fatty bone microenvironment, presenting, for the first time, with human adipocytes. Using this model, an increase in tumor burden is observed when human adipocytes are present, suggesting that adipocytes support early bone tumor growth. The advanced platform presented here combines natural aspects of the microenvironment with tunable properties useful for bone tumor research.

MechAnalyze: An Algorithm for Standardization and Automation of Compression Test Analysis

Publisher: Mary Ann Liebert Inc

Date: 10-2021

DOI: 10.1089/TEN.TEC.2021.0170

Erratum to: SnapShot: Polymer Scaffolds for Tissue Engineering [Biomaterials 30/4 (2009) 701–702]

Publisher: Elsevier BV

Date: 04-2009

DOI: 10.1016/J.BIOMATERIALS.2009.01.049

Rational design and fabrication of multiphasic soft network composites for tissue engineering articular cartilage: A numerical model-based approach

Publisher: Elsevier BV

Date: 05-2018

DOI: 10.1016/J.CEJ.2018.01.020

Dermal fibroblast infiltration of poly(ε-caprolactone) scaffolds fabricated by melt electrospinning in a direct writing mode

Publisher: IOP Publishing

Date: 27-02-2013

DOI: 10.1088/1758-5082/5/2/025001

Abstract: Melt electrospinning in a direct writing mode is a recent additive manufacturing approach to fabricate porous scaffolds for tissue engineering applications. In this study, we describe porous and cell-invasive poly (ε-caprolactone) scaffolds fabricated by combining melt electrospinning and a programmable x-y stage. Fibers were 7.5 ± 1.6 µm in diameter and separated by interfiber distances ranging from 8 to 133 µm, with an average of 46 ± 22 µm. Micro-computed tomography revealed that the resulting scaffolds had a highly porous (87%), three-dimensional structure. Due to the high porosity and interconnectivity of the scaffolds, a top-seeding method was adequate to achieve fibroblast penetration, with cells present throughout and underneath the scaffold. This was confirmed histologically, whereby a 3D fibroblast-scaffold construct with full cellular penetration was produced after 14 days in vitro. Immunohistochemistry was used to confirm the presence and even distribution of the key dermal extracellular matrix proteins, collagen type I and fibronectin. These results show that melt electrospinning in a direct writing mode can produce cell invasive scaffolds, using simple top-seeding approaches.

Cryoreservation of alginate–fibrin beads involving bone marrow derived mesenchymal stromal cells by vitrification

Publisher: Elsevier BV

Date: 2009

DOI: 10.1016/J.BIOMATERIALS.2008.09.030

Abstract: Application of cell--biomaterial systems in regenerative medicine can be facilitated by their successful low temperature preservation. Vitrification, which avoids ice crystal formation by amorphous solidification, is an emerging approach to cryopreservation. Developing vitrification strategy, effective cryopreservation of alginate-fibrin beads with porcine mesenchymal stromal cells has been achieved in this study. The cell-biomaterial constructs were pre-cultured for 20 days before cryopreservation, allowing for cell proliferation and construct stabilization. Ethylene glycol (EG) was employed as the basic cryoprotectant for two equilibration solutions. Successful cryopreservation of the constructs was achieved using vitrification solution composed of penetrating (EG MW 62 Da) and non-penetrating (sucrose MW 342 Da) cryoprotectants. Stepwise procedure of introduction to and removal of cryoprotectants was brief direct plunging into liquid nitrogen was applied. Cell viability, evaluated by combining live/death staining and confocal laser microscopy, was similar for both control and vitrified cells in the beads. No detectable damage of microstructure of cryopreserved beads was found as shown by scanning electron microscopy. Both osteogenically induced control and vitrified cells in the constructs were equally capable of mineral production and deposition. There was no statistically significant difference in metabolic activity and proliferation between both groups during the entire culture period. Our study leads to the conclusion that the developed cryopreservation protocol allowed to maintain the integrity of the beads while preserving the ability of the pig bone marrow derived mesenchymal stromal cells to proliferate and subsequently differentiate demonstrating that vitrification is a promising approach for cryopreservation of "ready-to-use" cell-biomaterial constructs.

Independent Evaluation of Medical-Grade Bioresorbable Filaments for Fused Deposition Modelling/Fused Filament Fabrication of Tissue Engineered Constructs

Publisher: MDPI AG

Date: 02-01-2018

DOI: 10.3390/POLYM10010040

Abstract: Three-dimensional printing/additive manufacturing (3DP/AM) for tissue engineering and regenerative medicine (TE/RM) applications is a multifaceted research area encompassing biology, material science, engineering, and the clinical sciences. Although being quite mature as a research area, only a handful of clinical cases have been reported and even fewer commercial products have made it to the market. The regulatory pathway and costs associated with the introduction of bioresorbable materials for TE/RM have proven difficult to overcome, but greater access to 3DP/AM has spurred interest in the processing and availability of existing and new bioresorbable materials. For this purpose, herein, we introduce a series of medical-grade filaments for fused deposition modelling/fused filament fabrication (FDM/FFF) based on established and Federal Drug Administration (FDA)-approved polymers. Manufacturability, mechanical characterization, and accelerated degradation studies have been conducted to evaluate the suitability of each material for TE/RM applications. The comparative data serves to introduce these materials, as well as a benchmark to evaluate their potential in hard and soft tissue engineering from a physicochemical perspective.

Human corneal epithelial equivalents constructed on Bombyx mori silk fibroin membranes

Publisher: Elsevier BV

Date: 08-2011

DOI: 10.1016/J.BIOMATERIALS.2011.03.068

Abstract: Membranes prepared from a protein, fibroin, isolated from domesticated silkworm (Bombyx mori) silk, support the cultivation of human limbal epithelial (HLE) cells and thus display significant potential as biomaterials for ocular surface reconstruction. We presently extend this promising avenue of research by directly comparing the attachment, morphology and phenotype of primary HLE cell cultures grown on fibroin to that observed on donor amniotic membrane (AM), the current clinical standard substrate for HLE transplantation. Fibroin membranes measuring 6.3 ± 0.5 μm (mean ± sd) in thickness and permeable to FITC dextran of a molecular weight up to 70 kDa, were used. Attachment of HLE cells to fibroin was similar to that supported by tissue culture plastic but approximately 6-fold less than that observed on AM. Nevertheless, epithelia constructed from HLE on fibroin maintained evidence of corneal phenotype (K3/K12 expression) and displayed a comparable number and distribution of ΔNp63(+) progenitor cells to that seen in cultures grown on AM. These results support the suitability of membranes constructed from Bombyx mori silk fibroin as substrata for HLE cultivation and encourage progression to studies of efficacy in preclinical models.

Co-culture of Bone Marrow Fibroblasts and Endothelial Cells on Modified Polycaprolactone Substrates for Enhanced Potentials in Bone Tissue Engineering

Publisher: Mary Ann Liebert Inc

Date: 09-2006

DOI: 10.1089/TEN.2006.12.2521

Abstract: The creation of a vascularized bed makes the survival of seeded cells on 3-dimensional scaffolds much more likely. However, relying purely on random capillary ingrowth into the porous scaffolds from the host may compromise vascularization of a scaffold. One solution is to transplant cells capable of differentiating into new blood vessels into the scaffolds to accelerate the creation of a vascularized scaffold. Because endothelial cells are the key cells involved in blood vessel formation, the present study was designed to investigate the development of a biomaterial surface that supports endothelial cell attachment and proliferation. The subsequent effects of the material surface modifications on the differentiation and proliferation of human bone marrow-derived fibroblasts (HBMFs) when grown in co-culture with a human bone marrow endothelial cell line (HBMEC-60) were studied. Endothelialization studies showed that the gelatin-coated and hydroxyapatite-coated substrates were superior for HBMEC-60 attachment and proliferation to hydrolyzed-only or untreated polycaprolactone substrates. Co-culture studies showed that the presence of the HBMEC-60 specifically enhanced HBMF cell proliferation and differentiation and that this effect was not observed with co-culture with skin fibroblasts. It is concluded that the co-culture of endothelial cells with HBMFs could be a promising culture system for bone tissue- engineering applications.

In vitro and in vivo analysis of co-electrospun scaffolds made of medical grade poly(ε-caprolactone) and porcine collagen

Publisher: Informa UK Limited

Date: 2008

DOI: 10.1163/156856208784089580

Abstract: In this study, a nanofiber mesh made by co-electrospinning medical grade poly(epsilon-caprolactone) and collagen (mPCL/Col) was fabricated and studied. Its mechanical properties and characteristics were analyzed and compared to mPCL meshes. mPCL/Col meshes showed a reduction in strength but an increase in ductility when compared to PCL meshes. In vitro assays revealed that mPCL/Col supported the attachment and proliferation of smooth muscle cells on both sides of the mesh. In vivo studies in the corpus cavernosa of rabbits revealed that the mPCL/Col scaffold used in conjunction with autologous smooth muscle cells resulted in better integration with host tissue when compared to cell free scaffolds. On a cellular level preseeded scaffolds showed a minimized foreign body reaction.

Hyaluronan-based heparin-incorporated hydrogels for generation of axially vascularized bioartificial bone tissues: in vitro and in vivo evaluation in a PLDLLA–TCP–PCL-composite system

Publisher: Springer Science and Business Media LLC

Date: 30-03-2011

DOI: 10.1007/S10856-011-4300-0

Abstract: Smart matrices are required in bone tissue-engineered grafts that provide an optimal environment for cells and retain osteo-inductive factors for sustained biological activity. We hypothesized that a slow-degrading heparin-incorporated hyaluronan (HA) hydrogel can preserve BMP-2 while an arterio-venous (A-V) loop can support axial vascularization to provide nutrition for a bio-artificial bone graft. HA was evaluated for osteoblast growth and BMP-2 release. Porous PLDLLA-TCP-PCL scaffolds were produced by rapid prototyping technology and applied in vivo along with HA-hydrogel, loaded with either primary osteoblasts or BMP-2. A microsurgically created A-V loop was placed around the scaffold, encased in an isolation chamber in Lewis rats. HA-hydrogel supported growth of osteoblasts over 8 weeks and allowed sustained release of BMP-2 over 35 days. The A-V loop provided an angiogenic stimulus with the formation of vascularized tissue in the scaffolds. Bone-specific genes were detected by real time RT-PCR after 8 weeks. However, no significant amount of bone was observed histologically. The heterotopic isolation chamber in combination with absent biomechanical stimulation might explain the insufficient bone formation despite adequate expression of bone-related genes. Optimization of the interplay of osteogenic cells and osteo-inductive factors might eventually generate sufficient amounts of axially vascularized bone grafts for reconstructive surgery.

Conceptual design of a personalized radiation therapy patch for skin cancer

Publisher: Walter de Gruyter GmbH

Date: 09-2018

DOI: 10.1515/CDBME-2018-0146

Abstract: Radiation therapy is a valuable option for treatment of skin cancer. In order to deliver the radiation dose to the superficial skin tumor, an X-ray source, electron beam radiation therapy or a radioisotope is applied. The effectiveness of these procedures is well established in the literature. Findings of some recent studies have indicated that beta particles can be of particular interest in suppressing skin tumor growth. Betaemitting radioisotopes are favorable because of the short penetration depth of their emitted particles. Beta radiation can induce significant damage in superficial skin tumor, and at the same time, result in enhanced protection of the underlying healthy tissues. In this study, we propose the design of a patch that can be used in beta radiation therapy of skin cancer patients. For that, we describe the components of this radioactive patch, as well as a proposal for the subsequent clinical application procedure. A scaffold was used as a substrate for embedding the desired beta-emitting radioisotope, and two layers of hydrogel to provide protection and shielding for the radioactively labelled scaffold. The proposed design could provide a universal platform for all beta-emitting radioisotopes. Depending on the depth of the tumor spread, a suitable beta emitter for that specific tumor can be selected and used. This is of particular and critical importance in cases where the tumor is located directly on top of the bone and for which the depth of penetration of radiation should be limited to only the tumor volume. The proposed design has the mechanical flexibility to adapt to curved body regions so as to allow the use in anatomically challenging areas of the body.

Delineating breast cancer cell interactions with engineered bone microenvironments

Publisher: Wiley

Date: 21-05-2013

DOI: 10.1002/JBMR.1875

Abstract: The mechanisms leading to colonization of metastatic breast cancer cells (BCa) in the skeleton are still not fully understood. Here, we demonstrate that mineralized extracellular matrices secreted by primary human osteoblasts (hOBM) modulate cellular processes associated with BCa colonization of bone. A panel of four BCa cell lines of different bone-metastatic potential (T47D, SUM1315, MDA-MB-231, and the bone-seeking subline MDA-MB-231BO) was cultured on hOBM. After 3 days, the metastatic BCa cells had undergone morphological changes on hOBM and were aligned along the hOBM's collagen type I fibrils that were decorated with bone-specific proteins. In contrast, nonmetastatic BCa cells showed a random orientation on hOBM. Atomic force microscopy-based single-cell force spectroscopy revealed that the metastatic cell lines adhered more strongly to hOBM compared with nonmetastatic cells. Function-blocking experiments indicated that β1 -integrins mediated cell adhesion to hOBM. In addition, metastatic BCa cells migrated directionally and invaded hOBM, which was accompanied by enhanced MMP-2 and -9 secretion. Furthermore, we observed gene expression changes associated with osteomimickry in BCa cultured on hOBM. As such, osteopontin mRNA levels were significantly increased in SUM1315 and MDA-MB-231BO cells in a β1 -integrin-dependent manner after growing for 3 days on hOBM compared with tissue culture plastic. In conclusion, our results show that extracellular matrices derived from human osteoblasts represent a powerful experimental platform to dissect mechanisms underlying critical steps in the development of bone metastases.

Data on in vitro and in vivo cell orientation on substrates with different topographies

Publisher: Elsevier BV

Date: 12-2015

DOI: 10.1016/J.DIB.2015.09.024

A Method for Prostate and Breast Cancer Cell Spheroid Cultures Using Gelatin Methacryloyl-Based Hydrogels

Publisher: Springer New York

Date: 2018

DOI: 10.1007/978-1-4939-7845-8_10

Abstract: Modern tissue engineering technologies have delivered tools to recreate a cell's naturally occurring niche in vitro and to investigate normal and pathological cell-cell and cell-niche interactions. Hydrogel biomaterials mimic crucial properties of native extracellular matrices, including mechanical support, cell adhesion sites and proteolytic degradability. As such, they are applied as 3D cell culture platforms to replicate tissue-like architectures observed in vivo, allowing physiologically relevant cell behaviors. Here we review bioengineered 3D approaches used for prostate and breast cancer. Furthermore, we describe the synthesis and use of gelatin methacryloyl-based hydrogels as in vitro 3D cancer model. This platform is used to engineer the microenvironments for prostate and breast cancer cells to study processes regulating spheroid formation, cell functions and responses to therapeutic compounds. Collectively, these bioengineered 3D approaches provide cell biologists with innovative pre-clinical tools that integrate the complexity of the disease seen in patients to advance our knowledge of cancer cell physiology and the contribution of a tumor's surrounding milieu.

Bone

Publisher: Springer International Publishing

Date: 2016

DOI: 10.1007/978-3-319-28386-9_9

In vitro engineering of a bone metastases model allows for study of the effects of antiandrogen therapies in advanced prostate cancer

Publisher: American Association for the Advancement of Science (AAAS)

Date: 02-07-2021

DOI: 10.1126/SCIADV.ABG2564

Abstract: In vitro engineering of a bone metastases model allows us to study the effects of antiandrogens in advanced prostate cancer.

In Vivo Mesenchymal Cell Recruitment by a Scaffold Loaded with Transforming Growth Factor β1 and the Potential for in Situ Chondrogenesis

Publisher: Mary Ann Liebert Inc

Date: 07-2002

DOI: 10.1089/107632702760184727

Abstract: The objectives of this study were (1) to develop a biphasic implant made of a bioresorbable polymeric scaffold in combination with TGF-beta1-loaded fibrin glue for tissue-engineering applications, and (2) to determine whether the implant made of a polycaprolactone (PCL) scaffold and TGF-beta1-loaded fibrin glue could recruit mesenchymal cells and induce the process of cartilage formation when implanted in ectopic sites. Twenty-four 6-month-old New Zealand White rabbits were used. Scaffolds loaded with various doses of TGF-beta1 in fibrin glue were implanted subcutaneously, intramuscularly, and subperiosteally. The rabbits were killed and implants were removed at 2, 4, and 6 weeks postoperatively. The specimens were subjected to various staining techniques for histological analysis. Light microscopic examination of all specimens revealed that the entire pore space of the scaffolds was filled with various tissues in each group. The entire volume of the scaffolds in the groups loaded with TGF-beta1 and implanted intramuscularly and subcutaneously was populated with mesenchymal cells surrounded with an abundant extracellular matrix and blood vessels. The scaffold loaded with TGF-beta1 and implanted subperiosteally was found to be richly populated with chondrocytes at 2 and 4 weeks and immature bone formation was identified at 6 weeks. We conclude that scaffolds loaded with TGF-beta1 can successfully recruit mesenchymal cells and that chondrogenesis occurred when this construct was implanted subperiosteally.

The quest for mechanically and biologically functional soft biomaterials via soft network composites

Publisher: Elsevier BV

Date: 07-2018

DOI: 10.1016/J.ADDR.2018.07.015

Abstract: Developing multifunctional soft biomaterials capable of addressing all the requirements of the complex tissue regeneration process is a multifaceted problem. In order to tackle the current challenges, recent research efforts are increasingly being directed towards biomimetic design concepts that can be translated into soft biomaterials via advanced manufacturing technologies. Among those, soft network composites consisting of a continuous hydrogel matrix and a reinforcing fibrous network closely resemble native soft biological materials in terms of design and composition as well as physicochemical properties. This article reviews soft network composite systems with a particular emphasis on the design, biomaterial and fabrication aspects within the context of soft tissue engineering and drug delivery applications.

Degradation and cell culture studies on block copolymers prepared by ring opening polymerization of ϵ‐caprolactone in the presence of poly(ethylene glycol)

Publisher: Wiley

Date: 23-03-2004

DOI: 10.1002/JBM.A.30008

Abstract: Poly(epsilon-caprolactone) (PCL) and its block copolymers with poly(ethylene glycol) (PEG) were prepared by ring-opening polymerization of epsilon-caprolactone in the presence of ethylene glycol or PEG, using zinc metal as catalyst. The resulting polymers were characterized by various analytical techniques such as (1)H NMR, SEC, DSC, IR, X-ray, ESEM, and CZE. PCL/PEG copolymers with long PCL chains presented the same crystalline structure as PCL homopolymer, whereas PEG-bearing short PCL blocks retained the crystalline structure of PEG and exhibited an hiphilic behavior in aqueous solutions. Degradation of PCL and PCL/PEG diblock and triblock copolymers was realized in a 0.13 M, pH 7.4 phosphate buffer at 37 degrees C. The results indicated that the copolymers exhibited higher hydrophilicity and degradability compared with the PCL homopolymer. Large amounts of PEG were released from the bulk after 60 weeks' degradation. In vitro cell culture studies were conducted on scaffolds manufactured via solid free form fabrication by using primary human and rat bone marrow derived stromal cells (hMSC, rMSC). Light, scanning electron, and confocal laser microscopy, as well as immunocytochemistry, showed cell attachment, proliferation, and extracellular matrix production on the surface, as well as inside the scaffold architecture. Copolymers showed better performance in the cell culture studies than the PCL homopolymer.

SpheroidSim—Preliminary evaluation of a new computational tool to predict the influence of cell cycle time and phase fraction on spheroid growth

Publisher: Wiley

Date: 11-09-2018

DOI: 10.1002/BTPR.2692

Abstract: There is a relative paucity of research that integrates materials science and bioengineering with computational simulations to decipher the intricate processes promoting cancer progression. Therefore, a first-generation computational model, SpheroidSim, was developed that includes a biological data set derived from a bioengineered spheroid model to obtain a quantitative description of cell kinetics. SpheroidSim is a 3D agent-based model simulating the growth of multicellular cancer spheroids. Cell cycle time and phases mathematically motivated the population growth. SpheroidSim simulated the growth dynamics of multiple spheroids by in idually defining a collection of specific phenotypic traits and characteristics for each cell. Experimental data derived from a hydrogel-based spheroid model were fit to the predictions providing insight into the influence of cell cycle time (CCT) and cell phase fraction (CPF) on the cell population. A comparison of the number of active cells predicted for each analysis showed that the value and method used to define CCT had a greater effect on the predicted cell population than CPF. The model predictions were similar to the experimental results for the number of cells, with the predicted total number of cells varying by 8% and 12%, respectively, compared to the experimental data. SpheroidSim is a first step in developing a biologically based predictive tool capable of revealing fundamental elements in cancer cell physiology. This computational model may be applied to study the effect of the microenvironment on spheroid growth and other cancer cell types that demonstrate a similar multicellular clustering behavior as the population develops. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1335-1343, 2018.

Species-specific homing mechanisms of human prostate cancer metastasis in tissue engineered bone

Publisher: Elsevier BV

Date: 04-2014

DOI: 10.1016/J.BIOMATERIALS.2014.01.062

Abstract: The development of effective therapeutic strategies against prostate cancer bone metastases has been impeded by the lack of adequate animal models that are able to recapitulate the biology of the disease in humans. Bioengineered approaches allow researchers to create sophisticated experimentally and physiologically relevant in vivo models to study interactions between cancer cells and their microenvironment under reproducible conditions. The aim of this study was to engineer a morphologically and functionally intact humanized organ bone which can serve as a homing site for human prostate cancer cells. Transplantation of biodegradable tubular composite scaffolds seeded with human mesenchymal progenitor cells and loaded with rhBMP-7 resulted in the development of a chimeric bone construct including a large number of human mesenchymal cells which were shown to be metabolically active and capable of producing extracellular matrix components. Micro-CT analysis demonstrated that the newly formed ossicle recapitulated the morphological features of a physiological organ bone with a trabecular network surrounded by a cortex-like outer structure. This microenvironment was supportive of the lodgement and maintenance of murine haematopoietic cell clusters, thus mimicking a functional organ bone. Bioluminescence imaging demonstrated that luciferase-transduced human PC3 cells reproducibly homed to the humanized tissue engineered bone constructs, proliferated, and developed macro-metastases. This model allows the analysis of interactions between human prostate cancer cells and a functional humanized bone organ within an immuno-incompetent murine host. The system can serve as a reproducible platform to study effects of therapeutics against prostate cancer bone metastases within a humanized microenvironment.

Gelatin Methacryloyl Hydrogels for the Localized Delivery of Cefazolin

Publisher: MDPI AG

Date: 16-11-2021

DOI: 10.3390/POLYM13223960

Abstract: The tuneability of hydrogels renders them promising candidates for local drug delivery to prevent and treat local surgical site infection (SSI) while avoiding the systemic side-effects of intravenous antibiotic injections. Here, we present a newly developed gelatin methacryloyl (GelMA)-based hydrogel drug delivery system (GelMA-DDS) to locally deliver the broad-spectrum antibiotic cefazolin for SSI prophylaxis and treatment. Antibiotic doses from 3 µg to 90 µg were loaded in photocrosslinked GelMA hydrogel discs with 5 to 15% w/v polymer concentration and drug encapsulation efficiencies, mechanical properties, crosslinking and release kinetics, as well as bacterial growth inhibition were assessed. Our results demonstrate that all GelMA groups supported excellent drug encapsulation efficiencies of up to 99%. Mechanical properties of the GelMA-DDS were highly tuneable and unaffected by the loading of small to medium doses of cefazolin. The diffusive and the proteolytic in vitro drug delivery of all investigated cefazolin doses was characterized by a burst release, and the delivered cefazolin amount was directly proportional to the encapsulated dose. Accelerated enzymatic degradation of the GelMA-DDS followed zero-order kinetics and was dependent on both the cefazolin dose and GelMA concentration (3–13 h). Finally, we demonstrate that cefazolin delivered from GelMA induced a dose-dependent antibacterial efficacy against S. aureus, in both a broth and a diffusive assay. The cefazolin-loaded GelMA-DDS presented here provides a highly tuneable and easy-to-use local delivery system for the prophylaxis and treatment of SSI.

Relative Reflection Difference as a Method for Measuring the Thickness of the Exfoliated MoSe₂ Layers

Publisher: Institute of Physics, Polish Academy of Sciences

Date: 08-2017

DOI: 10.12693/APHYSPOLA.132.316

Electrospraying, a reproducible method for production of polymeric microspheres for biomedical applications

Publisher: MDPI AG

Date: 05-01-2011

DOI: 10.3390/POLYM3010131

Convergence of regenerative medicine and synthetic biology to develop standardized and validated models of human diseases with clinical relevance

Publisher: Elsevier BV

Date: 12-2015

DOI: 10.1016/J.COPBIO.2015.06.001

Abstract: In order to progress beyond currently available medical devices and implants, the concept of tissue engineering has moved into the centre of biomedical research worldwide. The aim of this approach is not to replace damaged tissue with an implant or device but rather to prompt the patient's own tissue to enact a regenerative response by using a tissue-engineered construct to assemble new functional and healthy tissue. More recently, it has been suggested that the combination of Synthetic Biology and translational tissue-engineering techniques could enhance the field of personalized medicine, not only from a regenerative medicine perspective, but also to provide frontier technologies for building and transforming the research landscape in the field of in vitro and in vivo disease models.

The effect of rhBMP-2 on canine osteoblasts seeded onto 3D bioactive polycaprolactone scaffolds

Publisher: Elsevier BV

Date: 11-2004

DOI: 10.1016/J.BIOMATERIALS.2004.01.007

Addressing Patient Specificity in the Engineering of Tumor Models

Publisher: Frontiers Media SA

Date: 12-09-2019

DOI: 10.3389/FBIOE.2019.00217

Convergence of Machine Vision and Melt Electrowriting

Publisher: Wiley

Date: 08-06-2021

DOI: 10.1002/ADMA.202100519

Abstract: Melt electrowriting (MEW) is a high‐resolution additive manufacturing technology that balances multiple parametric variables to arrive at a stable fabrication process. The better understanding of this balance is underscored here using high‐resolution camera vision of jet stability profiles in different electrical fields. Complementing this visual information are fiber‐diameter measurements obtained at precise points, allowing the correlation to electrified jet properties. Two process signatures—the jet angle and for the first time, the Taylor cone area—are monitored and analyzed with a machine vision system, while SEM imaging for diameter measurement correlates real‐time information. This information, in turn, allows the detection and correction of fiber pulsing for accurate jet placement on the collector, and the in‐process assessment of the fiber diameter. Improved process control is used to successfully fabricate collapsible MEW tubes structures that require exceptional accuracy and printing stability. Using a precise winding angle of 60° and 300 layers, the resulting 12 mm‐thick tubular structures have elastic snap‐through instabilities associated with mechanical metamaterials. This study provides a detailed analysis of the fiber pulsing occurrence in MEW and highlights the importance of real‐time monitoring of the Taylor cone volume to better understand, control, and predict printing instabilities.

Evaluation of Ultra-Thin Poly(ε-Caprolactone) Films for Tissue-Engineered Skin

Publisher: Mary Ann Liebert Inc

Date: 08-2001

DOI: 10.1089/10763270152436490

Abstract: Various natural and synthetic polymeric materials have been used as scaffold matrices for tissue-engineered skin. However, the commercially available skin replacement products pose problems of poor mechanical properties and immunological rejection. We have thus developed a film of 5 microm thickness, via biaxial stretching of poly(epsilon-caprolactone) (PCL), as a potential matrix for living skin replacements. The aim of this study was to evaluate the feasibility of using biaxially stretched PCL films as matrices for culturing human dermal fibroblasts. For this purpose, we cultured human dermal fibroblasts for 7 days on the films. Glass cover slips and polyurethane (PU) sheets were used as controls. The data from phase contrast light, confocal laser, and scanning electron microscopy suggested that biaxially stretched PCL films support the attachment and proliferation of human dermal fibroblasts. Thymidine-labeling results showed quantitatively that cell proliferation on the PCL films was superior to that on the PU s les. These results indicated that biaxially stretched PCL films supported the growth of human dermal fibroblasts and might have potential to be applied in tissue engineering a dermal equivalent or skin graft.

Foreword

Publisher: Informa UK Limited

Date: 2008

DOI: 10.1163/156856208784089634

Non-linear optical microscopy and histological analysis of collagen, elastin and lysyl oxidase expression in breast capsular contracture

Publisher: Springer Science and Business Media LLC

Date: 04-06-2018

DOI: 10.1186/S40001-018-0322-0

Evaluation of polycaprolactone − poly-D,L-lactide copolymer as biomaterial for breast tissue engineering

Publisher: Wiley

Date: 07-2016

DOI: 10.1002/PI.5181

Convergence of scaffold-guided bone regeneration principles and microvascular tissue transfer surgery

Publisher: American Association for the Advancement of Science (AAAS)

Date: 05-05-2023

DOI: 10.1126/SCIADV.ADD6071

Abstract: A preclinical evaluation using a regenerative medicine methodology comprising an additively manufactured medical-grade ε-polycaprolactone β-tricalcium phosphate (mPCL-TCP) scaffold with a corticoperiosteal flap was undertaken in eight sheep with a tibial critical-size segmental bone defect (9.5 cm 3 , M size) using the regenerative matching axial vascularization (RMAV) approach. Biomechanical, radiological, histological, and immunohistochemical analysis confirmed functional bone regeneration comparable to a clinical gold standard control (autologous bone graft) and was superior to a scaffold control group (mPCL-TCP only). Affirmative bone regeneration results from a pilot study using an XL size defect volume (19 cm 3 ) subsequently supported clinical translation. A 27-year-old adult male underwent reconstruction of a 36-cm near-total intercalary tibial defect secondary to osteomyelitis using the RMAV approach. Robust bone regeneration led to complete independent weight bearing within 24 months. This article demonstrates the widely advocated and seldomly accomplished concept of “bench-to-bedside” research and has weighty implications for reconstructive surgery and regenerative medicine more generally.

Identification of Common Pathways Mediating Differentiation of Bone Marrow- and Adipose Tissue-Derived Human Mesenchymal Stem Cells into Three Mesenchymal Lineages

Publisher: Oxford University Press (OUP)

Date: 09-11-2006

DOI: 10.1634/STEMCELLS.2006-0394

Abstract: Mesenchymal stem cells derived from human bone marrow (hBMSCs) and human adipose tissue (hAMSCs) represent a useful source of progenitor cells for cell therapy and tissue engineering. However, it is not clear what the similarities and differences between them are. Like hBMSCs, hAMSCs can differentiate into osteogenic, adipogenic, and chondrogenic cells. Whether MSCs derived from different tissue sources represent fundamentally similar or different cell types is not clear. Given the possible different sources of MSCs for cell therapy, a comprehensive comparison of the different MSCs would be very useful. Here, we compared the transcriptome profile of hAMCS and hBMSCs during directed differentiation into bone, cartilage, and fat. Our data revealed considerable similarities between bone marrow-derived MSCs (BMSCs) and adipose tissue-derived MSCs (AMSCs). We uncovered an interesting bifurcation of pathways in both BMSCs and AMSCs, in which osteogenesis and adipogenesis appear to be linked in a differentiation branch separate from chondrogenesis. Our data suggest that although a set of common genes may be needed for early differentiation into all three lineages, a different set of signature genes is associated with maturation into fully differentiated cells. The recruitment of different late differentiation factors explains and supports our conclusion that BMSCs differentiate more efficiently into bone and cartilage, whereas AMSCs differentiate better into adipocytes. This study not only generated a rich database for continuing molecular characterization of various MSCs but also provided a rational basis for assessing qualities of MSCs from different sources for the purpose of cell-based therapy and tissue engineering.

Microassembly Fabrication of Tissue Engineering Scaffolds With Customized Design

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 07-2008

DOI: 10.1109/TASE.2008.917011

Stromal fibroblasts regulate microvascular-like network architecture in a bioengineered breast tumour angiogenesis model

Publisher: Elsevier BV

Date: 09-2020

DOI: 10.1016/J.ACTBIO.2020.07.036

Regenerative medicine will impact, but not replace, the medical device industry

Publisher: Informa UK Limited

Date: 07-2006

DOI: 10.1586/17434440.3.4.409

In vitro characterization of natural and synthetic dermal matrices cultured with human dermal fibroblasts

Publisher: Elsevier BV

Date: 06-2004

DOI: 10.1016/J.BIOMATERIALS.2003.09.058

Degradation mechanisms of polycaprolactone in the context of chemistry, geometry and environment

Publisher: Elsevier BV

Date: 09-2019

DOI: 10.1016/J.PROGPOLYMSCI.2019.05.004

Effect of the sterilization method on the properties of Bombyx mori silk fibroin films

Publisher: Elsevier BV

Date: 03-2013

DOI: 10.1016/J.MSEC.2012.10.016

Abstract: We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method.

A humanized orthotopic tumor microenvironment alters the bone metastatic tropism of prostate cancer cells

Publisher: Springer Science and Business Media LLC

Date: 30-08-2021

DOI: 10.1038/S42003-021-02527-X

Abstract: Prostate cancer (PCa) is the second most commonly diagnosed cancer in men, and bone is the most frequent site of metastasis. The tumor microenvironment (TME) impacts tumor growth and metastasis, yet the role of the TME in PCa metastasis to bone is not fully understood. We used a tissue-engineered xenograft approach in NOD- scid IL2Rγ null (NSG) mice to incorporate two levels of humanization the primary tumor and TME, and the secondary metastatic bone organ. Bioluminescent imaging, histology, and immunohistochemistry were used to study metastasis of human PC-3 and LNCaP PCa cells from the prostate to tissue-engineered bone. Here we show pre-seeding scaffolds with human osteoblasts increases the human cellular and extracellular matrix content of bone constructs, compared to unseeded scaffolds. The humanized prostate TME showed a trend to decrease metastasis of PC-3 PCa cells to the tissue-engineered bone, but did not affect the metastatic potential of PCa cells to the endogenous murine bones or organs. On the other hand, the humanized TME enhanced LNCaP tumor growth and metastasis to humanized and murine bone. Together this demonstrates the importance of the TME in PCa bone tropism, although further investigations are needed to delineate specific roles of the TME components in this context.

Cartilage regeneration using zonal chondrocyte subpopulations: a promising approach or an overcomplicated strategy?

Publisher: Hindawi Limited

Date: 08-11-2012

DOI: 10.1002/TERM.1638

Abstract: Cartilage defects heal imperfectly and osteoarthritic changes develop frequently as a result. Although the existence of specific behaviours of chondrocytes derived from various depth-related zones in vitro has been known for over 20 years, only a relatively small body of in vitro studies has been performed with zonal chondrocytes and current clinical treatment strategies do not reflect these native depth-dependent (zonal) differences. This is surprising since mimicking the zonal organization of articular cartilage in neo-tissue by the use of zonal chondrocyte subpopulations could enhance the functionality of the graft. Although some research groups including our own have made considerable progress in tailoring culture conditions using specific growth factors and biomechanical loading protocols, we conclude that an optimal regime has not yet been determined. Other unmet challenges include the lack of specific zonal cell sorting protocols and limited amounts of cells harvested per zone. As a result, the engineering of functional tissue has not yet been realized and no long-term in vivo studies using zonal chondrocytes have been described. This paper critically reviews the research performed to date and outlines our view of the potential future significance of zonal chondrocyte populations in regenerative approaches for the treatment of cartilage defects. Secondly, we briefly discuss the capabilities of additive manufacturing technologies that can not only create patient-specific grafts directly from medical imaging data sets but could also more accurately reproduce the complex 3D zonal extracellular matrix architecture using techniques such as hydrogel-based cell printing.

Mechanical properties and cell cultural response of polycaprolactone scaffolds designed and fabricated via fused deposition modeling

Publisher: Wiley

Date: 2001

DOI: 10.1002/1097-4636(200105)55:2<203::AID-JBM1007>3.0.CO;2-7

Abstract: A number of different processing techniques have been developed to design and fabricate three-dimensional (3D) scaffolds for tissue-engineering applications. The imperfection of the current techniques has encouraged the use of a rapid prototyping technology known as fused deposition modeling (FDM). Our results show that FDM allows the design and fabrication of highly reproducible bioresorbable 3D scaffolds with a fully interconnected pore network. The mechanical properties and in vitro biocompatibility of polycaprolactone scaffolds with a porosity of 61 +/- 1% and two matrix architectures were studied. The honeycomb-like pores had a size falling within the range of 360 x 430 x 620 microm. The scaffolds with a 0/60/120 degrees lay-down pattern had a compressive stiffness and a 1% offset yield strength in air of 41.9 +/- 3.5 and 3.1 +/- 0.1 MPa, respectively, and a compressive stiffness and a 1% offset yield strength in simulated physiological conditions (a saline solution at 37 degrees C) of 29.4 +/- 4.0 and 2.3 +/- 0.2 MPa, respectively. In comparison, the scaffolds with a 0/72/144/36/108 degrees lay-down pattern had a compressive stiffness and a 1% offset yield strength in air of 20.2 +/- 1.7 and 2.4 +/- 0.1 MPa, respectively, and a compressive stiffness and a 1% offset yield strength in simulated physiological conditions (a saline solution at 37 degrees C) of 21.5 +/- 2.9 and 2.0 +/- 0.2 MPa, respectively. Statistical analysis confirmed that the five-angle scaffolds had significantly lower stiffness and 1% offset yield strengths under compression loading than those with a three-angle pattern under both testing conditions (p < or = 0.05). The obtained stress-strain curves for both scaffold architectures demonstrate the typical behavior of a honeycomb structure undergoing deformation. In vitro studies were conducted with primary human fibroblasts and periosteal cells. Light, environmental scanning electron, and confocal laser microscopy as well as immunohistochemistry showed cell proliferation and extracellular matrix production on the polycaprolactone surface in the 1st culturing week. Over a period of 3-4 weeks in a culture, the fully interconnected scaffold architecture was completely 3D-filled by cellular tissue. Our cell culture study shows that fibroblasts and osteoblast-like cells can proliferate, differentiate, and produce a cellular tissue in an entirely interconnected 3D polycaprolactone matrix.

Myocyte enhancer factor 2C, an osteoblast transcription factor identified by dimethyl sulfoxide (DMSO)-enhanced mineralization

Publisher: Elsevier BV

Date: 08-2011

DOI: 10.1074/JBC.M111.253518

State of the art and future directions of scaffold-based bone engineering from a biomaterials perspective

Publisher: Hindawi Limited

Date: 2007

DOI: 10.1002/TERM.24

Abstract: Scaffold-based bone tissue engineering aims to repair/regenerate bone defects. Such a treatment concept involves seeding autologous osteogenic cells throughout a biodegradable scaffold to create a scaffold-cell hybrid that may be called a tissue-engineered construct (TEC). A variety of materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past two decades. This review aims to discuss the advances in bone engineering from a scaffold material point of view. In the first part the reader is introduced to the basic principles of bone engineering. The important properties of the biomaterials and the scaffold design in the making of tissue engineered bone constructs are discussed in detail, with special emphasis placed on the new material developments, namely composites made of synthetic polymers and calcium phosphates. Advantages and limitations of these materials are analysed along with various architectural parameters of scaffolds important for bone tissue engineering, e.g. porosity, pore size, interconnectivity and pore-wall microstructures.

ATF5, a possible regulator of osteogenic differentiation in human adipose‐derived stem cells

Publisher: Wiley

Date: 15-06-2012

DOI: 10.1002/JCB.24150

Abstract: The regulatory pathways involved in maintaining the pluripotency of embryonic stem cells are partially known, whereas the regulatory pathways governing adult stem cells and their "stem-ness" are characterized to an even lesser extent. We, therefore, screened the transcriptome profiles of 20 osteogenically induced adult human adipose-derived stem cell (ADSC) populations and investigated for putative transcription factors that could regulate the osteogenic differentiation of these ADSC. We studied a subgroup of donors' s les that had a disparate osteogenic response transcriptome from that of induced human fetal osteoblasts and the rest of the induced human ADSC s les. From our statistical analysis, we found activating transcription factor 5 (ATF5) to be significantly and consistently down-regulated in a randomized time-course study of osteogenically differentiated adipose-derived stem cells from human donor s les. Knockdown of ATF5 with siRNA showed an increased sensitivity to osteogenic induction. This evidence suggests a role for ATF5 in the regulation of osteogenic differentiation in adipose-derived stem cells. To our knowledge, this is the first report that indicates a novel role of transcription factors in regulating osteogenic differentiation in adult or tissue specific stem cells.

In vitro disease models 4.0 via automation and high-throughput processing

Publisher: IOP Publishing

Date: 11-07-2019

DOI: 10.1088/1758-5090/AB296F

Abstract: While much progress has been accomplished in the development of physiologically relevant in vitro disease models, current manufacturing and characterisation workflows still rely on manual, time-consuming, and low-throughput processes, which are not efficient and prone to human errors. For these reasons adoption and, more importantly, reproducibility and validation of 3D in vitro disease models is rather low for fundamental and applied research concepts. This article argues in form of a perspective view that automation and high-throughput methodologies will play a vital role to act as a catalyst to accelerate the development and characterisation process for generations to come. Innovative engineering concepts are required to overcome current limitations of in vitro disease models and to foster the scientific rigour as well as the applied research potential.

Comparative study of desktop- and synchrotron radiation-based micro computed tomography analyzing cell-seeded scaffolds in tissue engineering of bone

Publisher: SPIE

Date: 28-08-2008

DOI: 10.1117/12.797427

A bioengineered 3D ovarian cancer model for the assessment ofpeptidase-mediated enhancement of spheroid growth andintraperitoneal spread

Publisher: Elsevier BV

Date: 10-2013

DOI: 10.1016/J.BIOMATERIALS.2013.06.009

Abstract: Cancer-associated proteases promote peritoneal dissemination and chemoresistance in malignant progression. In this study, kallikrein-related peptidases 4, 5, 6, and 7 (KLK4-7)-cotransfected OV-MZ-6 ovarian cancer cells were embedded in a bioengineered three-dimensional (3D) microenvironment that contains RGD motifs for integrin engagement to analyze their spheroid growth and survival after chemotreatment. KLK4-7-cotransfected cells formed larger spheroids and proliferated more than controls in 3D, particularly within RGD-functionalized matrices, which was reduced upon integrin inhibition. In contrast, KLK4-7-expressing cell monolayers proliferated less than controls, emphasizing the relevance of the 3D microenvironment and integrin engagement. In a spheroid-based animal model, KLK4-7-overexpression induced tumor growth after 4 weeks and intraperitoneal spread after 8 weeks. Upon paclitaxel administration, KLK4-7-expressing tumors declined in size by 91% (controls: 87%) and showed 90% less metastatic outgrowth (controls: 33%, P < 0.001). KLK4-7-expressing spheroids showed 53% survival upon paclitaxel treatment (controls: 51%), accompanied by enhanced chemoresistance-related factors, and their survival was further reduced by combination treatment of paclitaxel with KLK4/5/7 (22%, P = 0.007) or MAPK (6%, P = 0.006) inhibition. The concomitant presence of KLK4-7 in ovarian cancer cells together with integrin activation drives spheroid formation and proliferation. Combinatorial approaches of paclitaxel and KLK/MAPK inhibition may be more efficient for late-stage disease than chemotherapeutics alone as these inhibitory regimens reduced cancer spheroid growth to a greater extent than paclitaxel alone.

Processing of Polycaprolactone and Polycaprolactone-Based Copolymers into 3D Scaffolds, and Their Cellular Responses

Publisher: Mary Ann Liebert Inc

Date: 10-2009

DOI: 10.1089/TEN.TEA.2008.0355

CD73 and CD29 concurrently mediate the mechanically induced decrease of migratory capacity of mesenchymal stromal cells

Publisher: European Cells and Materials

Date: 06-07-2011

DOI: 10.22203/ECM.V022A03

Abstract: e assumption that mesenchymal stromal cell (MSC)-based-therapies are capable of augmenting physiological regeneration processes has fostered intensive basic and clinical research activities. However, to achieve sustained therapeutic success in vivo, not only the biological, but also the mechanical microenvironment of MSCs during these regeneration processes needs to be taken into account. This is especially important for e.g., bone fracture repair, since MSCs present at the fracture site undergo significant biomechanical stimulation. This study has therefore investigated cellular characteristics and the functional behaviour of MSCs in response to mechanical loading. Our results demonstrated a reduced expression of MSC surface markers CD73 (ecto-5'-nucleotidase) and CD29 (integrin β1) after loading. On the functional level, loading led to a reduced migration of MSCs. Both effects persisted for a week after the removal of the loading stimulus. Specific inhibition of CD73/CD29 demonstrated their substrate dependent involvement in MSC migration after loading. These results were supported by scanning electron microscopy images and phalloidin staining of actin filaments displaying less cell spreading, lamellipodia formation and actin accumulations. Moreover, focal adhesion kinase and Src-family kinases were identified as candidate downstream targets of CD73/CD29 that might contribute to the mechanically induced decrease in MSC migration. These results suggest that MSC migration is controlled by CD73/CD29, which in turn are regulated by mechanical stimulation of cells. We therefore speculate that MSCs migrate into the fracture site, become mechanically entrapped, and thereby accumulate to fulfil their regenerative functions.

Preliminary study of a polycaprolactone membrane utilized as epidermal substrate

Publisher: Springer Science and Business Media LLC

Date: 2003

DOI: 10.1023/A:1022059511261

Abstract: Solvent-cast sheets of polycaprolactone were biaxially stretched to produce 10-15 microm thick films. PCL films were found to have a tensile strength of 55 MPa which is about two and a half times stronger than native skin. One of our previous studies using non-coated PCL membranes showed that only 36% of the membrane surface was covered with keratinocytes after 9 days of culture. The present study examined the effects of coating the surface of PCL membranes with fibrin on the proliferation of keratinocytes. Qualitative analysis revealed that the cells attached and proliferated better on coated PCL films. Keratinocytes exhibited healthy cobblestone morphology and proliferated as continuous monolayers over a period of 16 days. The results indicated that fibrin coated PCL films would support the attachment and proliferation of human keratinocytes and have the potential to be applied as a matrix material for tissue engineering an epidermal equivalent.

Lycopene's effects on cancer cell functions within monolayer and spheroid cultures

Publisher: Informa UK Limited

Date: 17-02-2016

DOI: 10.1080/01635581.2016.1150498

Abstract: Lycopene, a compound that blocks the action of free radicals and oxygen molecules, is found in tomatoes and tomato-based products and linked to a reduced incidence of cancer. Increasing willingness of patients to maintain a healthy lifestyle by supplemental intake of nutrients and acceptance of alternative therapeutics has boosted research into nutraceuticals. The potential of lycopene to prevent or treat cancer has been investigated, but outcomes are inconsistent and its mode of action is still unknown. Further studies are needed to understand the role of lycopene in cancer prevention and treatment. The impact of lycopene on viability, proliferation, migration, and invasion of five different cancer cell lines was determined using monolayer and spheroid cultures. Cell viability was significantly reduced upon lycopene treatment at physiologically attainable concentrations. Cell proliferation, migration, and invasion did not change upon lycopene treatment. Ovarian cancer spheroids initially showed a decreased proliferation and after 14 days increased cell viability upon lycopene treatment, confirming the potential of lycopene to reduce cancer cell growth in short-term cultures and also indicate enhanced cell viability over prolonged exposure. This study cannot substantiate that lycopene inhibits cell functions associated with tumor growth, even in a 3D cancer model that mimics the natural tumor microenvironment.

Sustained regeneration of high-volume adipose tissue for breast reconstruction using computer aided design and biomanufacturing

Publisher: Elsevier BV

Date: 06-2015

DOI: 10.1016/J.BIOMATERIALS.2015.01.025

Abstract: Adipose tissue engineering offers a promising alternative to the current breast reconstruction options. Here we investigated patient-specific breast scaffolds fabricated from poly(d,l)-lactide polymer with pore sizes>1 mm for their potential in long-term sustained regeneration of high volume adipose tissue. An optimised scaffold geometry was modelled in silico via a laser scanning data set from a patient who underwent breast reconstruction surgery. After the design process scaffolds were fabricated using an additive manufacturing technology termed fused deposition modelling. Breast-shaped scaffolds were seeded with human umbilical cord perivascular cells and cultured under static conditions for 4 weeks and subsequently 2 weeks in a biaxial rotating bioreactor. These in vitro engineered constructs were then seeded with human umbilical vein endothelial cells and implanted subcutaneously into athymic nude rats for 24 weeks. Angiogenesis and adipose tissue formation were observed throughout all constructs at all timepoints. The percentage of adipose tissue compared to overall tissue area increased from 37.17% to 62.30% between week 5 and week 15 (p<0.01), and increased to 81.2% at week 24 (p<0.01), while the seeded endothelial cells self-organised to form a functional capillary network. The presented approach of fabricating customised scaffolds using 3D scans represents a facile approach towards engineering clinically relevant volumes of adipose tissue for breast reconstruction.

A humanised tissue-engineered bone model allows species-specific breast cancer-related bone metastasis in vivo

Publisher: Hindawi Limited

Date: 29-11-2018

DOI: 10.1002/TERM.2517

Abstract: Bone metastases frequently occur in the advanced stages of breast cancer. At this stage, the disease is deemed incurable. To date, the mechanisms of breast cancer-related metastasis to bone are poorly understood. This may be attributed to the lack of appropriate animal models to investigate the complex cancer cell-bone interactions. In this study, two established tissue-engineered bone constructs (TEBCs) were applied to a breast cancer-related metastasis model. A cylindrical medical-grade polycaprolactone-tricalcium phosphate scaffold produced by fused deposition modelling (scaffold 1) was compared with a tubular calcium phosphate-coated polycaprolactone scaffold fabricated by solution electrospinning (scaffold 2) for their potential to generate ectopic humanised bone in NOD/SCID mice. While scaffold 1 was found not suitable to generate a sufficient amount of ectopic bone tissue due to poor ectopic integration, scaffold 2 showed excellent integration into the host tissue, leading to bone formation. To mimic breast cancer cell colonisation to the bone, MDA-MB-231, SUM1315, and MDA-MB-231BO breast cancer cells were cultured in polyethylene glycol-based hydrogels and implanted adjacent to the TEBCs. Histological analysis indicated that the breast cancer cells induced an osteoclastic reaction in the TEBCs, demonstrating analogies to breast cancer-related bone metastasis seen in patients.

Tissue engineered human prostate microtissues reveal key role of mast cell-derived tryptase in potentiating cancer-associated fibroblast (CAF)-induced morphometric transition in vitro

Publisher: Elsevier BV

Date: 03-2019

DOI: 10.1016/J.BIOMATERIALS.2018.12.030

Abstract: The tumour microenvironment plays a vital role in the development of solid malignancies. Here we describe an in vitro human prostate cancer microtissue model that facilitates the incorporation and interrogation of key elements of the local prostatic tumour microenvironment. Primary patient-derived cancer-associated fibroblasts (CAFs) were cultured in three-dimensional (3D) melt electrowritten scaffolds where they deposited extensive extracellular matrix (ECM) and promoted significant changes in prostate epithelial morphology, when compared to matched non-malignant prostatic fibroblasts (NPFs). The addition of mast cells, a resident prostatic immune population that is expanded during early malignancy, enhanced the morphometric transition of benign epithelia via a tryptase-mediated mechanism. Our patient-specific 3D microtissues reveal a cascade of interactions between prostatic CAFs, their native ECM and mast cell-derived tryptase, rendering them important microenvironmental drivers of prostate cancer progression.

Biological performance of a polycaprolactone-based scaffold plus recombinant human morphogenetic protein-2 (rhBMP-2) in an ovine thoracic interbody fusion model

Publisher: Springer Science and Business Media LLC

Date: 20-11-2013

DOI: 10.1007/S00586-013-3085-X

Vitrification as a prospect for cryopreservation of tissue-engineered constructs

Publisher: Elsevier BV

Date: 03-2007

DOI: 10.1016/J.BIOMATERIALS.2006.11.047

Abstract: Cryopreservation plays a significant function in tissue banking and will presume yet larger value when more and more tissue-engineered products will routinely enter the clinical arena. The most common concept underlying tissue engineering is to combine a scaffold (cellular solids) or matrix (hydrogels) with living cells to form a tissue-engineered construct (TEC) to promote the repair and regeneration of tissues. The scaffold and matrix are expected to support cell colonization, migration, growth and differentiation, and to guide the development of the required tissue. The promises of tissue engineering, however, depend on the ability to physically distribute the products to patients in need. For this reason, the ability to cryogenically preserve not only cells, but also TECs, and one day even whole laboratory-produced organs, may be indispensable. Cryopreservation can be achieved by conventional freezing and vitrification (ice-free cryopreservation). In this publication we try to define the needs versus the desires of vitrifying TECs, with particular emphasis on the cryoprotectant properties, suitable materials and morphology. It is concluded that the formation of ice, through both direct and indirect effects, is probably fundamental to these difficulties, and this is why vitrification seems to be the most promising modality of cryopreservation.

The influence of anisotropic nano- to micro-topography on in vitro and in vivo osteogenesis

Publisher: Future Medicine Ltd

Date: 03-2015

DOI: 10.2217/NNM.14.218

Abstract: Aim: Topographically modified substrates are increasingly used in tissue engineering to enhance biomimicry. The overarching hypothesis is that topographical cues will control cellular response at the cell–substrate interface. Materials & methods: The influence of anisotropically ordered poly(lactic-co-glycolic acid) substrates (constant groove width of ˜1860 nm constant line width of ˜2220 nm variable groove depth of ˜35, 306 and 2046 nm) on in vitro and in vivo osteogenesis were assessed. Results & discussion: We demonstrate that substrates with groove depths of approximately 306 and 2046 nm promote osteoblast alignment parallel to underlined topography in vitro. However, none of the topographies assessed promoted directional osteogenesis in vivo. Conclusion: 2D imprinting technologies are useful tools for in vitro cell phenotype maintenance.

Water as the often neglected medium at the interface between materials and biology

Publisher: Springer Science and Business Media LLC

Date: 21-07-2022

DOI: 10.1038/S41467-022-31889-X

Abstract: Despite its apparent simplicity, water behaves in a complex manner and is fundamental in controlling many physical, chemical and biological processes. The molecular mechanisms underlying interaction of water with materials, particularly polymer networks such as hydrogels, have received much attention in the research community. Despite this, a large gulf still exists in applying what is known to rationalize how the molecular organization of water on and within these materials impacts biological processes. In this perspective, we outline the importance of water in biomaterials science as a whole and give indications for future research directions towards emergence of a complete picture of water, materials and biology.

Biomimetic tubular nanofiber mesh and platelet rich plasma-mediated delivery of BMP-7 for large bone defect regeneration

Publisher: Springer Science and Business Media LLC

Date: 26-01-2012

DOI: 10.1007/S00441-011-1298-Z

Abstract: There is a growing need for successful bone tissue engineering strategies and advanced biomaterials that mimic the structure and function of native tissues carry great promise. Successful bone repair approaches may include an osteoconductive scaffold, osteoinductive growth factors, cells with an osteogenic potential and capacity for graft vascularisation. To increase osteoinductivity of biomaterials, the local combination and delivery of growth factors has been developed. In the present study we investigated the osteogenic effects of calcium phosphate (CaP)-coated nanofiber mesh tube-mediated delivery of BMP-7 from a PRP matrix for the regeneration of critical sized segmental bone defects in a small animal model. Bilateral full-thickness diaphyseal segmental defects were created in twelve male Lewis rats and nanofiber mesh tubes were placed around the defect. Defects received either treatment with a CaP-coated nanofiber mesh tube (n = 6), an un-coated nanofiber mesh tube (n=6) a CaP-coated nanofiber mesh tube with PRP (n=6) or a CaP-coated nanofiber mesh tube in combination with 5 μg BMP-7 and PRP (n = 6). After 12 weeks, bone volume and biomechanical properties were evaluated using radiography, microCT, biomechanical testing and histology. The results demonstrated significantly higher biomechanical properties and bone volume for the BMP group compared to the control groups. These results were supported by the histological evaluations, where BMP group showed the highest rate of bone regeneration within the defect. In conclusion, BMP-7 delivery via PRP enhanced functional bone defect regeneration, and together these data support the use of BMP-7 in the treatment of critical sized defects.

Mesenchymal stem/stromal cells enhance engraftment, vasculogenic and pro-angiogenic activities of endothelial colony forming cells in immunocompetent hosts

Publisher: Springer Science and Business Media LLC

Date: 19-10-2017

DOI: 10.1038/S41598-017-13971-3

Abstract: The clinical use of endothelial colony forming cells (ECFC) is h ered by their restricted engraftment. We aimed to assess engraftment, vasculogenic and pro-angiogenic activities of ECFC in immunocompetent (C57BL/6: WT) or immunodeficient ( rag1 −/− C57BL/6: Rag1) mice. In addition, the impact of host immune system was investigated where ECFC were co-implanted with mesenchymal stem/stromal cells (MSC) from adult bone marrow (AdBM-MSC), fetal bone marrow (fBM-MSC), fetal placental (fPL-MSC), or maternal placental (MPL-MSC). Transplantation of ECFCs in Matrigel plugs resulted in less cell engraftment in WT mice compared to Rag1 mice. Co-implantation with different MSCs resulted in a significant increase in cell engraftment up to 9 fold in WT mice reaching levels of engraftment observed when using ECFCs alone in Rag1 mice but well below levels of engraftment with MSC-ECFC combination in Rag1 recipients. Furthermore, MSCs did not reduce murine splenic T cell proliferation in response to ECFCs in vitro . ECFCs enhanced the murine neo-vascularization through paracrine effect, but with no difference between Rag1 and WT mice. In conclusions, the host adaptive immune system affects the engraftment of ECFCs. MSC co-implantation improves ECFC engraftment and function even in immunocompetent hosts mostly through non-immune mechanisms.

Single-Cell Force Spectroscopy, an Emerging Tool to Quantify Cell Adhesion to Biomaterials

Publisher: Mary Ann Liebert Inc

Date: 02-2014

DOI: 10.1089/TEN.TEB.2013.0125

Design, Fabrication and Physical Characterization of Scaffolds Made from Biodegradable Synthetic Polymers in combination with RP Systems based on Melt Extrusion

Publisher: Springer US

Date: 2008

DOI: 10.1007/978-0-387-68831-2_12

Strategies for zonal cartilage repair using hydrogels

Publisher: Wiley

Date: 03-11-2009

DOI: 10.1002/MABI.200900176

Abstract: Articular cartilage is a highly hydrated tissue with depth-dependent cellular and matrix properties that provide low-friction load bearing in joints. However, the structure and function are frequently lost and there is insufficient repair response to regenerate high-quality cartilage. Several hydrogel-based tissue-engineering strategies have recently been developed to form constructs with biomimetic zonal variations to improve cartilage repair. Modular hydrogel systems allow for systematic control over hydrogel properties, and advanced fabrication techniques allow for control over construct organization. These technologies have great potential to address many unanswered questions involved in prescribing zonal properties to tissue-engineered constructs for cartilage repair.

A humanized tissue-engineered in vivo model to dissect interactions between human prostate cancer cells and human bone

Publisher: Springer Science and Business Media LLC

Date: 08-02-2014

DOI: 10.1007/S10585-014-9638-5

Abstract: Currently used xenograft models for prostate cancer bone metastasis lack the adequate tissue composition necessary to study the interactions between human prostate cancer cells and the human bone microenvironment. We introduce a tissue engineering approach to explore the interactions between human tumor cells and a humanized bone microenvironment. Scaffolds, seeded with human primary osteoblasts in conjunction with BMP7, were implanted into immunodeficient mice to form humanized tissue engineered bone constructs (hTEBCs) which consequently resulted in the generation of highly vascularized and viable humanized bone. At 12 weeks, PC3 and LNCaP cells were injected into the hTEBCs. Seven weeks later the mice were euthanized. Micro-CT, histology, TRAP, PTHrP and osteocalcin staining results reflected the different characteristics of the two cell lines regarding their phenotypic growth pattern within bone. Microvessel density, as assessed by vWF staining, showed that tumor vessel density was significantly higher in LNCaP injected hTEBC implants than in those injected with PC3 cells (p < 0.001). Interestingly, PC3 cells showed morphological features of epithelial and mesenchymal phenotypes suggesting a cellular plasticity within this microenvironment. Taken together, a highly reproducible humanized model was established which is successful in generating LNCaP and PC3 tumors within a complex humanized bone microenvironment. This model simulates the conditions seen clinically more closely than any other model described in the literature to date and hence represents a powerful experimental platform that can be used in future work to investigate specific biological questions relevant to bone metastasis.

Investigating the effects of preinduction on human adipose-derived precursor cells in an athymic rat model

Publisher: Elsevier BV

Date: 12-2006

DOI: 10.1111/J.1432-0436.2006.00092.X

Abstract: The osteogenic potential of human adipose-derived precursor cells seeded on medical-grade polycaprolactone-tricalcium phosphate scaffolds was investigated in this in vivo study. Three study groups were investigated: (1) induced--stimulated with osteogenic factors only after seeding into scaffold (2) preinduced--induced for 2 weeks before seeding into scaffolds and (3) uninduced--cells without any introduced induction. For all groups, scaffolds were implanted subcutaneously into the dorsum of athymic rats. The scaffold/cell constructs were harvested at the end of 6 or 12 weeks and analyzed for osteogenesis. Gross morphological examination using scanning electron microscopy indicated good integration of host tissue with scaffold/cell constructs and extensive tissue infiltration into the scaffold interior. Alizarin Red histology and immunostaining showed a heightened level of mineralization and an increase in osteonectin, osteopontin, and collagen type I protein expression in both the induced and preinduced groups compared with the uninduced groups. However, no significant differences were observed in these indicators when compared between the induced and preinduced groups.

Growth factor-loaded microparticles for tissue engineering: The discrepancies of in vitro characterization assays

Publisher: Mary Ann Liebert Inc

Date: 02-2016

DOI: 10.1089/TEN.TEC.2015.0222

Bone response to unloaded titanium implants in the fibula, iliac crest, and scapula: an animal study in the Yorkshire pig

Publisher: Elsevier BV

Date: 08-2003

DOI: 10.1054/IJOM.2002.0367

Abstract: The reconstruction of extended maxillary and mandibular defects with prefabricated free flaps is a two stage procedure, that allows immediate function with implant supported dentures. The appropriate delay between prefabrication and reconstruction depends on the interfacial strength of the bone-implant surface. The purpose of this animal study was to evaluate the removal torque of unloaded titanium implants in the fibula, the scapula and the iliac crest. Ninety implants with a sandblasted and acid-etched (SLA) surface were tested after healing periods of 3, 6, and 12 weeks, respectively. Removal torque values (RTV) were collected using a computerized counterclockwise torque driver. The bicortical anchored 8mm implants in the fibula revealed values of 63.73 Ncm, 91.50 Ncm, and 101.83 Ncm at 3, 6, and 12 weeks, respectively. The monocortical anchorage in the iliac crest showed values of 71.40 Ncm, 63.14 Ncm, and 61.59 Ncm with 12 mm implants at the corresponding times. The monocortical anchorage in the scapula demonstrated mean RTV of 62.28 Ncm, 97.63 Ncm, and 99.7 Ncm with 12 mm implants at 3, 6, and 12 weeks, respectively. The study showed an increase of removal torque with increasing healing time. The interfacial strength for bicortical anchored 8mm implants in the fibula was comparable to monocortical anchored 12 mm implants in the iliac crest and the scapula at the corresponding times. The resistance to shear seemed to be determined by the type of anchorage (monocortical vs. bicortical) and the length of the implant with greater amount of bone-implant interface.

The influence of fibrin based hydrogels on the chondrogenic differentiation of human bone marrow stromal cells

Publisher: Elsevier BV

Date: 2010

DOI: 10.1016/J.BIOMATERIALS.2009.09.021

Abstract: Mesenchymal Stem Cells (MSC) are frequently incorporated into osteochondral implants and cell seeding is often facilitated with hydrogels which exert a profound influence on the chondrogenic differentiation of MSC. An attempt was made to elucidate this effect by comparing the chondrogenic differentiation of Bone Marrow Stromal Cells (BMSC) in fibrin and fibrin alginate composites. A biphasic osteochondral model which simulated the native in vivo environment was employed in the study. In the first stage of the experiment, BMSC was encapsulated in fibrin, Fibrin Alginate 0.3% (FA0.3) and 0.6% (FA0.6). Chondrogenic differentiation within these cell-hydrogel pellets was compared against that of standard cell pellets under inductive conditions and the matrices which supported chondrogenesis were used in the cartilage phase of biphasic constructs. Neo-cartilage growth was monitored in these cocultures. It was observed that hydrogel encapsulation influenced mesenchymal condensation which preceded chondrogenic differentiation. Early cell agglomeration was observed in fibrin as compared to fibrin alginate composites. These fibrin encapsulated cells differentiated into chondrocytes which secreted aggrecan and collagen II. When the alginate content rose from 0.3 to 0.6%, chondrogenic differentiation declined with a reduction in the expression of collagen II and aggrecan. Fibrin and FA0.3 were tested in the cartilage phase of the biphasic osteochondral constructs and the former supported superior cartilage growth with higher cellularity, total Glycosaminoglycan (GAG) and collagen II levels. The FA0.3 cartilage phase was found to be fragmented and partially calcified. The use of fibrin for cartilage repair was advocated as it facilitated BMSC chondrogenesis and cartilaginous growth in an osteochondral environment.

Evaluation of methods for cultivating limbal mesenchymal stromal cells

Publisher: Elsevier BV

Date: 09-2012

DOI: 10.3109/14653249.2012.684379

Melt electrospinning of poly(ε-caprolactone) scaffolds: Phenomenological observations associated with collection and direct writing

Publisher: Elsevier BV

Date: 12-2014

DOI: 10.1016/J.MSEC.2014.07.034

Abstract: Melt electrospinning and its additive manufacturing analogue, melt electrospinning writing (MEW), are two processes which can produce porous materials for applications where solvent toxicity and accumulation in solution electrospinning are problematic. This study explores the melt electrospinning of poly(ε-caprolactone) (PCL) scaffolds, specifically for applications in tissue engineering. The research described here aims to inform researchers interested in melt electrospinning about technical aspects of the process. This includes rapid fiber characterization using glass microscope slides, allowing influential processing parameters on fiber morphology to be assessed, as well as observed fiber collection phenomena on different collector substrates. The distribution and alignment of melt electrospun PCL fibers can be controlled to a certain degree using patterned collectors to create large numbers of scaffolds with shaped macroporous architectures. However, the buildup of residual charge in the collected fibers limits the achievable thickness of the porous template through such scaffolds. One challenge identified for MEW is the ability to control charge buildup so that fibers can be placed accurately in close proximity, and in many centimeter heights. The scale and size of scaffolds produced using MEW, however, indicate that this emerging process will fill a technological niche in biofabrication.

Developing macroporous bicontinuous materials as scaffolds for tissue engineering

Publisher: Elsevier BV

Date: 10-2005

DOI: 10.1016/J.BIOMATERIALS.2005.02.011

Abstract: Calcareous skeletal elements (ossicles) isolated from the seastar, Pisaster giganteus, were characterized and tested as potential biocompatible substrates for cellular attachment. These ossicles have a remarkably robust open-framework architecture with an interconnected network of ca. 10 microm diameter pores. Scanning electron and confocal microscopy was used to characterize the cell-substrate interaction. Cell culturing experiments revealed that the cells firmly attach to the ossicle surface, forming cell aggregates of several layers thick. The anchored cells extended to form 'bridges' between the openings in the bicontinuous framework and the degree of coverage increased as culture time progressed. Osteoblasts grown on the ossicles were found to be viable up to 32 days after initial seeding, as proven by assaying with AlamarBlue and FDA/PI staining indicating the ossicle's potential as an alternative highly effective tissue scaffold. Given the limitation in availability of this natural material, the results presented here should be seen as offering guidelines for future development of synthetic materials with physical and chemical properties strongly conducive to bone repair and restoration.

Breast Reconstruction Using Biofabrication-Based Tissue Engineering Strategies

Publisher: Elsevier

Date: 2013

DOI: 10.1016/B978-1-4557-2852-7.00010-X

Current developments in multifunctional smart materials for 3D/4D bioprinting

Publisher: Elsevier BV

Date: 06-2017

DOI: 10.1016/J.COBME.2017.04.002

Rekonstruktion der Kalvaria durch ein präfabriziertes bioaktives Implantat

Publisher: Georg Thieme Verlag KG

Date: 10-03-2010

DOI: 10.1055/S-0030-1248310

Abstract: Osseous craniofacial defects are commonly seen problems after operative treatment of craniosynostoses. This case report describes a calvarial reconstruction by means of computer-aided fabrication of a customised implant. Three-dimensional imaging is followed by computer-aided design and fabrication of a medical grade PCL-TCP biodegradable scaffold using the rapid prototyping technology fused deposition modelling (CAD/CAM). After six months the implant was well integrated, no defect area could be palpated any more and a beginning bony consolidation could be detected via CT.

Osteo-maturation of adipose-derived stem cells required the combined action of vitamin D3, β-glycerophosphate, and ascorbic acid

Publisher: Elsevier BV

Date: 10-2007

DOI: 10.1016/J.BBRC.2007.07.112

Abstract: This study investigated the effects of various components [vitamin D3 (VD3), beta-glycerophosphate (BGP), and ascorbic acid (AA)] on the potential of human adipose-derived progenitor cells (ADPCs) to transdifferentiate into osteoblast-like cells. ADPCs were induced under four different supplement groups: (1) VD3+BGP+AA, (2) VD3 alone, (3) BGP+AA, and (4) no VD3, BGP or AA. Mineralization studies and presence of bone matrix-related proteins by immunostaining showed that the Group 1 ADPCs showed their ability to undergo osteoblastic differentiation. Further evaluation was made by estimation of levels of RUNX-2 and TAZ genes. Group 1 ADPCs showed the consistent expression of RUNX-2 and TAZ levels over the study period of 28days. The study showed good correlation among various parameters evaluated to conclude that ADPCs could be an alternative source for generating osteoblast-like cells.

Regenerative matching axial vascularisation of absorbable 3D-printed scaffold for large bone defects: A first in human series

Publisher: Elsevier BV

Date: 07-2022

DOI: 10.1016/J.BJPS.2022.02.057

Analysis of 3D bone ingrowth into polymer scaffolds via micro-computed tomography imaging

Publisher: Elsevier BV

Date: 09-2004

DOI: 10.1016/J.BIOMATERIALS.2004.01.047

Computational fluid dynamics for improved bioreactor design and 3D culture

Publisher: Elsevier BV

Date: 04-2008

DOI: 10.1016/J.TIBTECH.2007.11.012

Abstract: The complex relationship between the hydrodynamic environment and surrounding tissues directly impacts on the design and production of clinically useful grafts and implants. Tissue engineers have generally seen bioreactors as 'black boxes' within which tissue engineering constructs (TECs) are cultured. It is accepted that a more detailed description of fluid mechanics and nutrient transport within process equipment can be achieved by using computational fluid dynamics (CFD) technology. This review discusses applications of CFD for tissue engineering-related bioreactors -- fluid flow processes have direct implications on cellular responses such as attachment, migration and proliferation. We conclude that CFD should be seen as an invaluable tool for analyzing and visualizing the impact of fluidic forces and stresses on cells and TECs.

Characterization of Osteogenically Induced Adipose Tissue-Derived Precursor Cells in 2-Dimensional and 3-Dimensional Environments

Publisher: S. Karger AG

Date: 2006

DOI: 10.1159/000091713

Abstract: Earlier reports on a putative precursor cell population in adipose tissue showed differentiation along several mesodermal lineages, leading some to think that adipose tissue can be a source of cells applicable in regenerative medicine. However, characterizations of these adipose-derived precursor cells (ADPC) in the 3-dimensional (3-D) environment, especially within the area of bone-specific composite scaffolds, have been lacking. In this study, ADPC plated on culture flasks or seeded on medical grade polycaprolactone-tricalcium phosphate scaffolds (mPCL-CaP) were able to differentiate along the osteogenic lineages in both 2-D and 3-D environments as assessed with immunohistochemistry of osteo-related proteins, reverse transcriptase-polymerase chain reactions and alkaline phosphatase assay. The mPCL-CaP scaffolds provided adipose-derived cells (ADC) with a suitable environment as determined by DNA and metabolic assays, light, confocal and scanning electron microscopy. Flow cytometry revealed ADC to be CD29+, CD44+, CD73+, CD90+ and CD14–, CD31–, CD34–, CD45–, CD71–, and therefore showed the absence of hematopoietic stem cells but possibly the presence of pericytes and mescenchymal stem cells with osteogenic potential. The results of this study demonstrated the potential of using ADPC in combination with mPCL-CaP scaffolds for bone regenerative medicine.

Elucidating the molecular mechanisms for the interaction of water with polyethylene glycol-based hydrogels: Influence of ionic strength and gel network structure

Publisher: MDPI AG

Date: 10-03-2021

DOI: 10.3390/POLYM13060845

Abstract: The interaction of water within synthetic and natural hydrogel systems is of fundamental importance in biomaterial science. A systematic study is presented on the swelling behavior and states of water for a polyethylene glycol-diacrylate (PEGDA)-based model neutral hydrogel system that goes beyond previous studies reported in the literature. Hydrogels with different network structures are crosslinked and swollen in different combinations of water and phosphate-buffered saline (PBS). Network variables, polyethylene glycol (PEG) molecular weight (MW), and weight fraction are positively correlated with swelling ratio, while “non-freezable bound water” content decreases with PEG MW. The presence of ions has the greatest influence on equilibrium water and “freezable” and “non-freezable” water, with all hydrogel formulations showing a decreased swelling ratio and increased bound water as ionic strength increases. Similarly, the number of “non-freezable bound water” molecules, calculated from DSC data, is greatest—up to six molecules per PEG repeat unit—for gels swollen in PBS. Fundamentally, the balance of osmotic pressure and non-covalent bonding is a major factor within the molecular structure of the hydrogel system. The proposed model explains the dynamic interaction of water within hydrogels in an osmotic environment. This study will point toward a better understanding of the molecular nature of the water interface in hydrogels.

Tissue engineered prefabricated vascularized flaps

Publisher: Wiley

Date: 2007

DOI: 10.1002/HED.20546

Abstract: BACKGROUND.: Microvascular free tissue transfer has become increasingly popular in the reconstruction of head and neck defects, but it also has its disadvantages. Tissue engineering allows the generation of neo-tissue for implantation, but these tissues are often avascular. We propose to combine tissue-engineering techniques together with flap prefabrication techniques to generate a prefabricated vascularized soft tissue flap. Human dermal fibroblasts (HDFs) labeled with fluorescein diacetate were static seeded onto polylactic-co-glycolic acid-collagen (PLGA-c) mesh. Controls were plain PLGA-c mesh. The femoral artery and vein of the nude rat was ligated and used as a vascular carrier for the constructs. After 4 weeks of implantation, the constructs were assessed by gross morphology, routine histology, Masson trichrome, and cell viability determined by green fluorescence. All the constructs maintained their initial shape and dimensions. Angiogenesis was evident in all the constructs with neo-capillary formation within the PLGA-c mesh seen. HDFs proliferated and filled the interyarn spaces of the PLGA-c mesh, while unseeded PLGA-c mesh remained relatively acellular. Cell tracer study indicated that the seeded HDFs remained viable and closely associated to remaining PLGA-c fibers. Collagen formation was more abundant in the constructs seeded with HDFs. PLGA-c, enveloped by a cell sheet composed of fibroblasts, can serve as a suitable scaffold for generation of a soft tissue flap. A ligated arteriovenous pedicle can serve as a vascular carrier for the generation of a tissue engineered vascularized flap.

Biomaterials offer cancer research the third dimension

Publisher: Springer Science and Business Media LLC

Date: 02-2010

DOI: 10.1038/NMAT2619

Abstract: To deepen understanding and hasten the development of treatments, cancer needs to be modelled more accurately in vitro applying tissue-engineering concepts and approaches in this field could bridge the gap between two-dimensional studies and in vivo animal models.

A Novel 3D Cultured Model for Studying Early Changes in Age-Related Macular Degeneration

Publisher: Wiley

Date: 27-10-2017

DOI: 10.1002/MABI.201700221

Abstract: Various in vitro culture systems have been used to investigate the pathogenesis of age-related macular degeneration (AMD). However, many still rely on oversimplified monolayer culture models. AMD is a complex disease, associated with the pathological changes to multiple structural components such as the Bruch's membrane, retinal pigment epithelium (RPE), and choroidal endothelial cells. This study aims to construct a novel 3D coculture model using the polycaprolactone (PCL)-gelatin electrospun scaffold, with human RPE cells (hRPE) and primate choroidal cells (RF-6A). Results from this study show that PCL-gelatin scaffolds have a highly porous ultrastructure that supports the attachment, proliferation, differentiation, and migration of the hRPEs and choroidal endothelial cells. It is also demonstrated that the PCL-gelatin 3D coculture model may be useful in exploring the molecular interplay between the hPRE and the choroidal endothelial cells, and their effects on growth factor modulation, which may be important in the pathogenesis of AMD.

Melimine-Modified 3D-Printed Polycaprolactone Scaffolds for the Prevention of Biofilm-Related Biomaterial Infections

Publisher: American Chemical Society (ACS)

Date: 17-10-2022

DOI: 10.1021/ACSNANO.2C05812

Tissue engineered humanized bone supports human hematopoiesis in vivo

Publisher: Elsevier BV

Date: 08-2015

DOI: 10.1016/J.BIOMATERIALS.2015.04.057

Abstract: Advances in tissue-engineering have resulted in a versatile tool-box to specifically design a tailored microenvironment for hematopoietic stem cells (HSCs) in order to study diseases that develop within this setting. However, most current in vivo models fail to recapitulate the biological processes seen in humans. Here we describe a highly reproducible method to engineer humanized bone constructs that are able to recapitulate the morphological features and biological functions of the HSC niches. Ectopic implantation of biodegradable composite scaffolds cultured for 4 weeks with human mesenchymal progenitor cells and loaded with rhBMP-7 resulted in the development of a chimeric bone organ including a large number of human mesenchymal cells which were shown to be metabolically active and capable of establishing a humanized microenvironment supportive of the homing and maintenance of human HSCs. A syngeneic mouse-to-mouse transplantation assay was used to prove the functionality of the tissue-engineered ossicles. We predict that the ability to tissue engineer a morphologically intact and functional large-volume bone organ with a humanized bone marrow compartment will help to further elucidate physiological or pathological interactions between human HSCs and their native niches.

An electrospun polycaprolactone–collagen membrane for the resurfacing of cartilage defects

Publisher: Wiley

Date: 11-02-2010

DOI: 10.1002/PI.2792

Assessment of static and perfusion methods for decellularization of PCL membrane-supported periodontal ligament cell sheet constructs

Publisher: Elsevier BV

Date: 04-2018

DOI: 10.1016/J.ARCHORALBIO.2018.01.014

Abstract: Decellularization aims to harness the regenerative properties of native extracellular matrix. The objective of this study was to evaluate different methods of decellularization of periodontal ligament cell sheets whilst maintaining their structural and biological integrity. Human periodontal ligament cell sheets were placed onto melt electrospun polycaprolactone (PCL) membranes that reinforced the cell sheets during the various decellularization protocols. These cell sheet constructs (CSCs) were decellularized under static erfusion conditions using a) 20 mM ammonium hydroxide (NH4OH)/Triton X-100, 0.5% v/v and b) sodium dodecyl sulfate (SDS, 0.2% v/v), both +/- DNase besides Freeze-thaw (F/T) cycling method. CSCs were assessed using a collagen quantification assay, immunostaining and scanning electron microscopy. Residual fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were assessed with Bio-plex assays. DNA removal without DNase was higher under static conditions. However, after DNase treatment, there were no differences between the different decellularization methods with virtually 100% DNA removal. DNA elimination in F/T was less efficient even after DNase treatment. Collagen content was preserved with all techniques, except with SDS treatment. Structural integrity was preserved after NH4OH/Triton X-100 and F/T treatment, while SDS altered the extracellular matrix structure. Growth factor amounts were reduced after decellularization with all methods, with the greatest reduction (to virtually undetectable amounts) following SDS treatment, while NH4OH/Triton X-100 and DNase treatment resulted in approximately 10% retention. This study showed that treatment with NH4OH/Triton X-100 and DNase solution was the most efficient method for DNA removal and the preservation of extracellular matrix integrity and growth factors retention.

Invention and Business Performance in the Tissue-Engineering Industry

Publisher: Mary Ann Liebert Inc

Date: 12-2003

DOI: 10.1089/10763270360728224

Abstract: Tissue engineering is a young and interdisciplinary scientific discipline but it offers exciting opportunities to improve the quality of health care for hundreds of thousands of patients. Lured by its potential, several start-up companies, pharmaceutical corporations, and medical device enterprises alike are investing heavily in this sector. Invention is a key driver of competition in this sector. In this study, we aim to explain the variation in inventive output across the different firms in the sector. Our major premise is that firms that forge alliances will be able to tap into the expertise of their partners and thus improve their chances of inventive output. We further argue that alliances that enable technology acquisition or learning will enhance the inventive output of firms more than other kinds of alliances. We measure the inventive output of a company by the number of patents filed. On the basis of a preliminary analysis of seven companies, we find support for the hypotheses. We also argue that, to achieve commercial success, firms need to manage time to market (through alliances or otherwise), have a global outlook, nurture their financial resources, and attain critical mass through mergers.

Biodegradable interbody cages for lumbar spine fusion: Current concepts and future directions

Publisher: Elsevier BV

Date: 09-2022

DOI: 10.1016/J.BIOMATERIALS.2022.121699

Abstract: Lumbar fusion often remains the last treatment option for various acute and chronic spinal conditions, including infectious and degenerative diseases. Placement of a cage in the intervertebral space has become a routine clinical treatment for spinal fusion surgery to provide sufficient biomechanical stability, which is required to achieve bony ingrowth of the implant. Routinely used cages for clinical application are made of titanium (Ti) or polyetheretherketone (PEEK). Ti has been used since the 1980s however, its shortcomings, such as impaired radiographical opacity and higher elastic modulus compared to bone, have led to the development of PEEK cages, which are associated with reduced stress shielding as well as no radiographical artefacts. Since PEEK is bioinert, its osteointegration capacity is limited, which in turn enhances fibrotic tissue formation and peri-implant infections. To address shortcomings of both of these biomaterials, interdisciplinary teams have developed biodegradable cages. Rooted in promising preclinical large animal studies, a hollow cylindrical cage (Hydrosorb™) made of 70:30 poly-l-lactide-co-d, l-lactide acid (PLDLLA) was clinically studied. However, reduced bony integration and unfavourable long-term clinical outcomes prohibited its routine clinical application. More recently, scaffold-guided bone regeneration (SGBR) with application of highly porous biodegradable constructs is emerging. Advancements in additive manufacturing technology now allow the cage designs that match requirements, such as stiffness of surrounding tissues, while providing long-term biomechanical stability. A favourable clinical outcome has been observed in the treatment of various bone defects, particularly for 3D-printed composite scaffolds made of medical-grade polycaprolactone (mPCL) in combination with a ceramic filler material. Therefore, advanced cage design made of mPCL and ceramic may also carry initial high spinal forces up to the time of bony fusion and subsequently resorb without clinical side effects. Furthermore, surface modification of implants is an effective approach to simultaneously reduce microbial infection and improve tissue integration. We present a design concept for a scaffold surface which result in osteoconductive and antimicrobial properties that have the potential to achieve higher rates of fusion and less clinical complications. In this review, we explore the preclinical and clinical studies which used bioresorbable cages. Furthermore, we critically discuss the need for a cutting-edge research program that includes comprehensive preclinical in vitro and in vivo studies to enable successful translation from bench to bedside. We develop such a conceptual framework by examining the state-of-the-art literature and posing the questions that will guide this field in the coming years.

Fusion Performance of a Bioresorbable Cage Used In Porcine Model of Anterior Lumbar Interbody Fusion

Publisher: Springer Berlin Heidelberg

Date: 2009

DOI: 10.1007/978-3-540-92841-6_365

Examination of the foreign body response to biomaterials by nonlinear intravital microscopy

Publisher: Springer Science and Business Media LLC

Date: 19-12-2016

DOI: 10.1038/S41551-016-0007

A Preclinical Animal Model for the Study of Scaffold-Guided Breast Tissue Engineering

Publisher: Mary Ann Liebert Inc

Date: 06-2021

DOI: 10.1089/TEN.TEC.2020.0387

Individuell mit CAD-CAM-Technik hergestellte, bioresorbierbare dreidimensionale Polycaprolaktongerüste zur experimentellen Rekonstruktion von kraniofazialen Defekten beim Schwein

Publisher: Springer Science and Business Media LLC

Date: 2002

DOI: 10.1007/S10006-002-0389-0

Abstract: Twenty orbital defects (2 x 2 cm) were created in ten adult Yorkshire pigs. Two software products (Velocity and Mimix) were evaluated with regard to image processing, three-dimensional reconstruction, and fabrication of in idually shaped polycaprolactone (PCL) scaffolds to reconstruct these defects. Four different techniques were tested for the reconstruction: group 1 = no reconstruction, group 2 = polylactide sheet, group 3 = PCL scaffold, group 4 = bone marrow-coated PCL scaffold. The pigs were sacrificed at 3 months. In group 1 soft tissue scar formation could be found, but without any new bone. Group 2 showed a thick fibrous capsule around the PLLA sheet, whereas at the border zone of the defect signs of new bone formation could be detected. In group 3 the PCL scaffolds were filled with fibrous tissue and some areas that showed new bone formation (6.4% of the area of the defect). In group 4 the new bone formation (17.8% of the area of the defect) was significantly higher in quantity than in group 3. The PCL scaffold coated with bone marrow seems to be a material that effectively provides osteoinduction with formation of new bone. Long-term results at 12 months are still pending.

Flow modelling within a scaffold under the influence of uni-axial and bi-axial bioreactor rotation

Publisher: Elsevier BV

Date: 09-2005

DOI: 10.1016/J.JBIOTEC.2005.03.021

Abstract: The problem of donor scarcity has led to the recent development of tissue engineering technologies, which aim to create implantable tissue equivalents for clinical transplantation. These replacement tissues are being realised through the use of biodegradable polymer scaffolds temporary ermanent substrates, which facilitate cell attachment, proliferation, retention and differentiated tissue function. To optimise gas transfer and nutrient delivery, as well as to mimic the fluid dynamic environment present within the body, a dynamic system might be chosen. Experiments have shown that dynamic systems enhance tissue growth, with the aid of scaffolds, as compared to static culture systems. Very often, tissue growth within scaffolds is only seen to occur at the periphery. The present study utilises the Computational Fluid Dynamics package FLUENT, to provide a better understanding of the flow phenomena in scaffolds, within our novel bioreactor system. The uni-axial and bi-axial rotational schemes are studied and compared, based on a vessel rotating speed of 35 rpm. The wall shear stresses within and without the constructs are also studied. Findings show that bi-axial rotation of the vessel results in manifold increases of fluid velocity within the constructs, relative to uni-axial rotation about the X- and Z-axes, respectively.

Mimicking breast cancer-induced bone metastasis in vivo: current transplantation models and advanced humanized strategies

Publisher: Springer Science and Business Media LLC

Date: 27-04-2014

DOI: 10.1007/S10555-014-9499-Z

Abstract: Bone metastasis is a complication that occurs in 80 % of women with advanced breast cancer. Despite the prevalence of bone metastatic disease, the avenues for its clinical management are still restricted to palliative treatment options. In fact, the underlying mechanisms of breast cancer osteotropism have not yet been fully elucidated due to a lack of suitable in vivo models that are able to recapitulate the human disease. In this work, we review the current transplantation-based models to investigate breast cancer-induced bone metastasis and delineate the strengths and limitations of the use of different grafting techniques, tissue sources, and hosts. We further show that humanized xenograft models incorporating human cells or tissue grafts at the primary tumor site or the metastatic site mimic more closely the human disease. Tissue-engineered constructs are emerging as a reproducible alternative to recapitulate functional humanized tissues in these murine models. The development of advanced humanized animal models may provide better platforms to investigate the mutual interactions between human cancer cells and their microenvironment and ultimately improve the translation of preclinical drug trials to the clinic.

A novel 3D mammalian cell perfusion-culture system in microfluidic channels

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B614872G

Abstract: Mammalian cells cultured on 2D surfaces in microfluidic channels are increasingly used in drug development and biological research applications. These systems would have more biological or clinical relevance if the cells exhibit 3D phenotypes similar to the cells in vivo. We have developed a microfluidic channel based system that allows cells to be perfusion-cultured in 3D by supporting them with adequate 3D cell-cell and cell-matrix interactions. The maximal cell-cell interaction was achieved by perfusion-seeding cells through an array of micropillars and 3D cell-matrix interactions were achieved by a polyelectrolyte complex coacervation process to form a thin layer of matrix conforming to the 3D cell shapes. Carcinoma cell lines (HepG2, MCF7), primary differentiated (hepatocytes) and primary progenitor cells (bone marrow mesenchymal stem cells) were perfusion-cultured for 72 hours to 1 week in the microfluidic channel, which preserved their 3D cyto-architecture and cell-specific functions or differentiation competence. This transparent 3D microfluidic channel-based cell culture system also allows direct optical monitoring of cellular events for a wide range of applications.

Matrices for tissue-engineered skin

Publisher: Portico

Date: 2002

DOI: 10.1358/DOT.2002.38.2.820107

Abstract: Academic, clinical and industrial efforts are increasingly being directed toward the use of molecular- and cell-based therapies for diagnosis and treatment of a great number and broad variety of pathologies and injuries. Hence, tissue engineering is, next to genetic engineering, widely heralded as the healthcare technology heir of the revolutionary advances in life sciences. In a cost-controlled healthcare environment, only those technologies capable of providing a major enhancement to quality of life and a reduction in expenditure will be driven forward. Skin tissue engineering concepts based on the application of a scaffold/cell construct represent a treatment concept with the clear potential to meet this criterion. Several important issues concerning the research and product strategy (e.g., choice of matrix of natural or synthetic polymer origin and the use of autogenic versus allogenic cells) remain to be fully resolved. However, there is little doubt that wound regeneration via modern tissue engineering strategies will present significant therapeutic benefits when compared with existing treatments. This paper reviews the biography and future research directions of matrices used in skin tissue engineering.

Current strategies for cell delivery in cartilage and bone regeneration

Publisher: Elsevier BV

Date: 10-2004

DOI: 10.1016/J.COPBIO.2004.08.010

Abstract: Several cell-based tissue-engineering therapies are emerging to regenerate damaged tissues. These strategies use autologous cells in combination with bioresorbable delivery materials. Major functions of a delivery scaffold are to provide initial mechanical stability, homogenous three-dimensional cell distribution, improved tissue differentiation, suitable handling and properties for delivery and fixation into patients. Delivery of cells can be achieved using injectable matrices, soft scaffolds, membranes, solid load-bearing scaffolds or immunoprotective macroencapsulation. Thus, to expand the clinical potential, next generation therapies will depend on smart delivery concepts that make use of the regenerative potential of stem cells, morphogenetic growth factors and biomimetic materials.

Comparison of chondrogenesis in static and dynamic environments using a SFF designed and fabricated PCL-PEO scaffold

Publisher: Informa UK Limited

Date: 12-2008

DOI: 10.1080/17452750802598117

Deciphering the molecular mechanism of water interaction with gelatin methacryloyl hydrogels: Role of ionic strength, ph, drug loading and hydrogel network characteristics

Publisher: MDPI AG

Date: 19-05-2021

DOI: 10.3390/BIOMEDICINES9050574

Abstract: Water plays a primary role in the functionality of biomedical polymers such as hydrogels. The state of water, defined as bound, intermediate, or free, and its molecular organization within hydrogels is an important factor governing biocompatibility and hemocompatibility. Here, we present a systematic study of water states in gelatin methacryloyl (GelMA) hydrogels designed for drug delivery and tissue engineering applications. We demonstrate that increasing ionic strength of the swelling media correlated with the proportion of non-freezable bound water. We attribute this to the capability of ions to create ion–dipole bonds with both the polymer and water, thereby reinforcing the first layer of polymer hydration. Both pH and ionic strength impacted the mesh size, having potential implications for drug delivery applications. The mechanical properties of GelMA hydrogels were largely unaffected by variations in ionic strength or pH. Loading of cefazolin, a small polar antibiotic molecule, led to a dose-dependent increase of non-freezable bound water, attributed to the drug’s capacity to form hydrogen bonds with water, which helped recruit water molecules in the hydrogels’ first hydration layer. This work enables a deeper understanding of water states and molecular arrangement at the hydrogel–polymer interface and how environmental cues influence them.

Personalized, Mechanically Strong, and Biodegradable Coronary Artery Stents via Melt Electrowriting

Publisher: American Chemical Society (ACS)

Date: 16-11-2020

DOI: 10.1021/ACSMACROLETT.0C00644

Can Bone Tissue Engineering Contribute to Therapy Concepts after Resection of Musculoskeletal Sarcoma?

Publisher: Hindawi Limited

Date: 2013

DOI: 10.1155/2013/153640

Abstract: Resection of musculoskeletal sarcoma can result in large bone defects where regeneration is needed in a quantity far beyond the normal potential of self-healing. In many cases, these defects exhibit a limited intrinsic regenerative potential due to an adjuvant therapeutic regimen, seroma, or infection. Therefore, reconstruction of these defects is still one of the most demanding procedures in orthopaedic surgery. The constraints of common treatment strategies have triggered a need for new therapeutic concepts to design and engineer unparalleled structural and functioning bone grafts. To satisfy the need for long-term repair and good clinical outcome, a paradigm shift is needed from methods to replace tissues with inert medical devices to more biological approaches that focus on the repair and reconstruction of tissue structure and function. It is within this context that the field of bone tissue engineering can offer solutions to be implemented into surgical therapy concepts after resection of bone and soft tissue sarcoma. In this paper we will discuss the implementation of tissue engineering concepts into the clinical field of orthopaedic oncology.

Histomorphometric Evaluation of Critical-Sized Bone Defects Using Osteomeasure and Aperio Image Analysis Systems

Publisher: Mary Ann Liebert Inc

Date: 12-2019

DOI: 10.1089/TEN.TEC.2019.0179

The return of a forgotten polymer—Polycaprolactone in the 21st century

Publisher: Elsevier BV

Date: 10-2010

DOI: 10.1016/J.PROGPOLYMSCI.2010.04.002

The Challenge to Measure Cell Proliferation in Two and Three Dimensions

Publisher: Mary Ann Liebert Inc

Date: 2005

DOI: 10.1089/TEN.2005.11.182

Abstract: Various assays, using different strategies, are available for assessing cultured cell proliferation. These include measurement of metabolic activity (tetrazolium salts and alamarBlue), DNA quantification using fluorophores (Hoechst 33258 and PicoGreen), uptake of radioactively-labeled DNA precursors such as [3H]thymidine, and physical counting (hemocytometer). These assays are well established in characterizing cell proliferation in two-dimensional (2D), monolayer cultures of low cell densities. However, increasing interest in 3D cultures has prompted the need to evaluate the effectiveness of using these assays in high cell density or 3D cultures. We show here that typical cell proliferation assays do not necessarily correlate linearly with increasing cell densities or between 2D and 3D cultures, and are either not suitable or only rough approximations in quantifying actual cell numbers in a culture. Prudent choice of techniques and careful interpretation of data are therefore recommended when measuring cell proliferation in high cell density and 3D cultures.

Efficacy of glow discharge gas plasma treatment as a surface modification process for three‐dimensional poly (D,L‐lactide) scaffolds

Publisher: Wiley

Date: 25-04-2003

DOI: 10.1002/JBM.A.10478

Abstract: Gas plasma surface modification of three-dimensional poly (D,L-lactide) scaffolds fabricated by a novel vibrating particle fabrication technique was demonstrated to enhance cell adhesion, proliferation, and differentiation over 10 days in culture using human embryonic palatal mesenchyme cells. Characterization of corresponding two-dimensional treated surfaces revealed decreased contact angle measurements of 54.2 +/- 0.6 degrees for treated surfaces compared to 72.3 +/- 0.7 degrees for control surfaces (p < 0.05). SEM of treated surfaces revealed increased surface roughness combined with marked pitting and erosion. This may contribute to increased cell adhesion. WST-1 cell proliferation assay measurements as an index of cell numbers revealed a statistically significant increase in proliferation activity on treated surfaces on days 1 and 4 compared with controls. There was a fivefold increase in WST-1 activity for both control and treated groups over 10 days. Confocal laser micrographs revealed increased cell numbers on treated specimens throughout all layers of the scaffold, indicating that the glow discharge process enhanced cell proliferation throughout the entire scaffold architecture. Scanning electron micrographs demonstrated increased cell adhesion for treated specimens at the polymer surface most evident after days 1 and 4 of culture. Alkaline phosphatase (ALP)-specific activity peaked by day 7 for control and treated surfaces, indicating cellular differentiation. There was a trend for increased protein production on the treated specimens compared with controls at the initial time points although the differences were not statistically significant. These results demonstrated that gas plasma surface modification enhances osteoblast-like cell function in a three-dimensional scaffold model.

Tuning the hydrophobicity of plasma polymer coated silica particles

Publisher: Elsevier BV

Date: 11-2013

DOI: 10.1016/J.POWTEC.2013.09.018

Electrospinning and additive manufacturing: Converging technologies

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C2BM00039C

A fluorescence-based opto-mechatronic screening module (OMSM) for automated 3D cell culture workflows

Publisher: Elsevier BV

Date: 09-2023

DOI: 10.1016/J.BIOSX.2023.100372

Dynamics of in vitro polymer degradation of polycaprolactone-based scaffolds: accelerated versus simulated physiological conditions

Publisher: IOP Publishing

Date: 08-08-2008

DOI: 10.1088/1748-6041/3/3/034108

Abstract: The increasing use of biodegradable devices in tissue engineering and regenerative medicine means it is essential to study and understand their degradation behaviour. Accelerated degradation systems aim to achieve similar degradation profiles within a shorter period of time, compared with standard conditions. However, these conditions only partially mimic the actual situation, and subsequent analyses and derived mechanisms must be treated with caution and should always be supported by actual long-term degradation data obtained under physiological conditions. Our studies revealed that polycaprolactone (PCL) and PCL-composite scaffolds degrade very differently under these different degradation conditions, whilst still undergoing hydrolysis. Molecular weight and mass loss results differ due to the different degradation pathways followed (surface degradation pathway for accelerated conditions and bulk degradation pathway for simulated physiological conditions). Crystallinity studies revealed similar patterns of recrystallization dynamics, and mechanical data indicated that the scaffolds retained their functional stability, in both instances, over the course of degradation. Ultimately, polymer degradation was shown to be chiefly governed by molecular weight, crystallinity susceptibility to hydrolysis and device architecture considerations whilst maintaining its thermodynamic equilibrium.

Breast augmentation and reconstruction from a regenerative medicine point of view: State of the art and future perspectives

Publisher: Mary Ann Liebert Inc

Date: 06-2017

DOI: 10.1089/TEN.TEB.2016.0303

Reinforcement of hydrogels using three-dimensionally printed microfibres

Publisher: Springer Science and Business Media LLC

Date: 28-04-2015

DOI: 10.1038/NCOMMS7933

Abstract: Despite intensive research, hydrogels currently available for tissue repair in the musculoskeletal system are unable to meet the mechanical, as well as the biological, requirements for successful outcomes. Here we reinforce soft hydrogels with highly organized, high-porosity microfibre networks that are 3D-printed with a technique termed as melt electrospinning writing. We show that the stiffness of the gel/scaffold composites increases synergistically (up to 54-fold), compared with hydrogels or microfibre scaffolds alone. Modelling affirms that reinforcement with defined microscale structures is applicable to numerous hydrogels. The stiffness and elasticity of the composites approach that of articular cartilage tissue. Human chondrocytes embedded in the composites are viable, retain their round morphology and are responsive to an in vitro physiological loading regime in terms of gene expression and matrix production. The current approach of reinforcing hydrogels with 3D-printed microfibres offers a fundament for producing tissue constructs with biological and mechanical compatibility.

Scaffold-based bone engineering by using genetically modified cells

Publisher: Elsevier BV

Date: 02-2005

DOI: 10.1016/J.GENE.2004.12.040

Abstract: The first generation of clinically applied tissue engineering concepts in the area of skin, cartilage and bone marrow regeneration was based on the isolation, expansion and implantation of cells from the patient's own tissue. Although successful in selective treatments, tissue engineering needs to overcome major challenges to allow widespread clinical application with predictable outcomes. One challenge is to present the cells in a matrix to the implantation site to allow the cells to survive the wound healing contraction forces, tissue remodeling in certain tissues such as bone and biomechanical loading. Hence, several tissue engineering strategies focus on the development of load-bearing scaffold/cell constructs. From a cell source point of view, bone engineers face challenges to isolate and expand cells with the highest potential to form osseous tissue along with harvesting tissue without extensive donor site morbidity. A major hurdle to tissue engineering is de-differentiation and limited ability to control cell phenotype following in vitro expansion. Due to early successes with genetic engineering, bone tissue engineers have used different strategies to genetically alter various types of mesenchymal cells to enhance the mineralization capacity of tissue-engineered scaffold/cell constructs. Although the development of multi-component scaffold/osteogenic cell constructs requires a combination of interdisciplinary research strategies, the following review is limited to describe the general aspects of bone engineering and to present overall directions of technology platforms, which include a genetic engineering component. This paper reviews the most recent work in the field and discusses the concepts developed and executed by a collaborative effort of the multi-disciplinary teams of the two authors.

Design and fabrication of scaffold-based tissue engineering

Publisher: Walter de Gruyter GmbH

Date: 2013

DOI: 10.1515/BNM-2013-0021

25th anniversary article: Engineering hydrogels for biofabrication

Publisher: Wiley

Date: 23-08-2013

DOI: 10.1002/ADMA.201302042

Abstract: With advances in tissue engineering, the possibility of regenerating injured tissue or failing organs has become a realistic prospect for the first time in medical history. Tissue engineering - the combination of bioactive materials with cells to generate engineered constructs that functionally replace lost and/or damaged tissue - is a major strategy to achieve this goal. One facet of tissue engineering is biofabrication, where three-dimensional tissue-like structures composed of biomaterials and cells in a single manufacturing procedure are generated. Cell-laden hydrogels are commonly used in biofabrication and are termed "bioinks". Hydrogels are particularly attractive for biofabrication as they recapitulate several features of the natural extracellular matrix and allow cell encapsulation in a highly hydrated mechanically supportive three-dimensional environment. Additionally, they allow for efficient and homogeneous cell seeding, can provide biologically-relevant chemical and physical signals, and can be formed in various shapes and biomechanical characteristics. However, despite the progress made in modifying hydrogels for enhanced bioactivation, cell survival and tissue formation, little attention has so far been paid to optimize hydrogels for the physico-chemical demands of the biofabrication process. The resulting lack of hydrogel bioinks have been identified as one major hurdle for a more rapid progress of the field. In this review we summarize and focus on the deposition process, the parameters and demands of hydrogels in biofabrication, with special attention to robotic dispensing as an approach that generates constructs of clinically relevant dimensions. We aim to highlight this current lack of effectual hydrogels within biofabrication and initiate new ideas and developments in the design and tailoring of hydrogels. The successful development of a "printable" hydrogel that supports cell adhesion, migration, and differentiation will significantly advance this exciting and promising approach for tissue engineering.

Melt electrospinning today: An opportune time for an emerging polymer process

Publisher: Elsevier BV

Date: 05-2016

DOI: 10.1016/J.PROGPOLYMSCI.2016.01.001

A preclinical large-animal model for the assessment of critical-size load-bearing bone defect reconstruction

Publisher: Springer Science and Business Media LLC

Date: 14-02-2020

DOI: 10.1038/S41596-019-0271-2

Development of perforated microthin poly(ε-caprolactone) films as matrices for membrane tissue engineering

Publisher: Informa UK Limited

Date: 2004

DOI: 10.1163/156856204323046933

Abstract: The design and fabrication of thin films based on bioresorbable polymers such as poly(epsilon-caprolactone) (PCL) has been the focus of a part of current biomedical research, especially as matrices for membrane tissue engineering. We have successfully developed perforated microthin PCL membrane for this purpose. Two critical issues are the control of moisture permeability and understanding the degradation of PCL microthin film. In order to increase the moisture permeability. PCL films were biaxially stretched to a thickness of 10 +/- 3 microm and perforated with uniform array of holes (180-275 microm) using a Sony Robotic system. After perforation, the water vapour transmission rate was increased by 50% to a value of 47.6 +/- 2.7 g/h per m2. Accelerated hydrolytic degradations were performed in 5 M NaOH. The degraded s les were characterised for changes in weight, surface morphology, mechanical properties, crystallinity and molecular weight. Hydrolytic degradation commenced with random chain scission of backbone ester bonds on the film surface and followed by loss of material due to surface erosion. In general, the perforated films degraded faster than the unperforated microthin films. Scanning electron microscopic images showed that surface erosion led to extensive formation of micropores, microcracks and increased in surface roughness.

Sustained release and osteogenic potential of heparan sulfate-doped fibrin glue scaffolds within a rat cranial model

Publisher: Springer Science and Business Media LLC

Date: 12-09-2007

DOI: 10.1007/S10735-007-9137-Y

Abstract: This paper explores the potential therapeutic role of the naturally occurring sugar heparan sulfate (HS) for the augmentation of bone repair. Scaffolds comprising fibrin glue loaded with 5 microg of embryonically derived HS were assessed, firstly as a release-reservoir, and secondly as a scaffold to stimulate bone regeneration in a critical size rat cranial defect. We show HS-loaded scaffolds have a uniform distribution of HS, which was readily released with a typical burst phase, quickly followed by a prolonged delivery lasting several days. Importantly, the released HS contributed to improved wound healing over a 3-month period as determined by microcomputed tomography (microCT) scanning, histology, histomorphometry, and PCR for osteogenic markers. In all cases, only minimal healing was observed after 1 and 3 months in the absence of HS. In contrast, marked healing was observed by 3 months following HS treatment, with nearly full closure of the defect site. PCR analysis showed significant increases in the gene expression of the osteogenic markers Runx2, alkaline phosphatase, and osteopontin in the heparin sulfate group compared with controls. These results further emphasize the important role HS plays in augmenting wound healing, and its successful delivery in a hydrogel provides a novel alternative to autologous bone graft and growth factor-based therapies.

Animal models for bone tissue engineering and modelling disease

Publisher: The Company of Biologists

Date: 04-2018

DOI: 10.1242/DMM.033084

Abstract: Tissue engineering and its clinical application, regenerative medicine, are instructing multiple approaches to aid in replacing bone loss after defects caused by trauma or cancer. In such cases, bone formation can be guided by engineered biodegradable and nonbiodegradable scaffolds with clearly defined architectural and mechanical properties informed by evidence-based research. With the ever-increasing expansion of bone tissue engineering and the pioneering research conducted to date, preclinical models are becoming a necessity to allow the engineered products to be translated to the clinic. In addition to creating smart bone scaffolds to mitigate bone loss, the field of tissue engineering and regenerative medicine is exploring methods to treat primary and secondary bone malignancies by creating models that mimic the clinical disease manifestation. This Review gives an overview of the preclinical testing in animal models used to evaluate bone regeneration concepts. Immunosuppressed rodent models have shown to be successful in mimicking bone malignancy via the implantation of human-derived cancer cells, whereas large animal models, including pigs, sheep and goats, are being used to provide an insight into bone formation and the effectiveness of scaffolds in induced tibial or femoral defects, providing clinically relevant similarity to human cases. Despite the recent progress, the successful translation of bone regeneration concepts from the bench to the bedside is rooted in the efforts of different research groups to standardise and validate the preclinical models for bone tissue engineering approaches.

The Next Frontier in Melt Electrospinning: Taming the Jet

Publisher: Wiley

Date: 18-08-2019

DOI: 10.1002/ADFM.201904664

Concise Review: Humanized Models of Tumor Immunology in the 21st Century: Convergence of Cancer Research and Tissue Engineering

Publisher: Oxford University Press (OUP)

Date: 21-05-2015

DOI: 10.1002/STEM.1978

Abstract: Despite positive testing in animal studies, more than 80% of novel drug candidates fail to proof their efficacy when tested in humans. This is primarily due to the use of preclinical models that are not able to recapitulate the physiological or pathological processes in humans. Hence, one of the key challenges in the field of translational medicine is to “make the model organism mouse more human.” To get answers to questions that would be prognostic of outcomes in human medicine, the mouse's genome can be altered in order to create a more permissive host that allows the engraftment of human cell systems. It has been shown in the past that these strategies can improve our understanding of tumor immunology. However, the translational benefits of these platforms have still to be proven. In the 21st century, several research groups and consortia around the world take up the challenge to improve our understanding of how to humanize the animal's genetic code, its cells and, based on tissue engineering principles, its extracellular microenvironment, its tissues, or entire organs with the ultimate goal to foster the translation of new therapeutic strategies from bench to bedside. This article provides an overview of the state of the art of humanized models of tumor immunology and highlights future developments in the field such as the application of tissue engineering and regenerative medicine strategies to further enhance humanized murine model systems. Stem Cells 2015 :1696–1704

Porous scaffold architecture guides tissue formation

Publisher: Wiley

Date: 17-05-2012

DOI: 10.1002/JBMR.1589

Abstract: Critical-sized bone defect regeneration is a remaining clinical concern. Numerous scaffold-based strategies are currently being investigated to enable in vivo bone defect healing. However, a deeper understanding of how a scaffold influences the tissue formation process and how this compares to endogenous bone formation or to regular fracture healing is missing. It is hypothesized that the porous scaffold architecture can serve as a guiding substrate to enable the formation of a structured fibrous network as a prerequirement for later bone formation. An ovine, tibial, 30-mm critical-sized defect is used as a model system to better understand the effect of the scaffold architecture on cell organization, fibrous tissue, and mineralized tissue formation mechanisms in vivo. Tissue regeneration patterns within two geometrically distinct macroscopic regions of a specific scaffold design, the scaffold wall and the endosteal cavity, are compared with tissue formation in an empty defect (negative control) and with cortical bone (positive control). Histology, backscattered electron imaging, scanning small-angle X-ray scattering, and nanoindentation are used to assess the morphology of fibrous and mineralized tissue, to measure the average mineral particle thickness and the degree of alignment, and to map the local elastic indentation modulus. The scaffold proves to function as a guiding substrate to the tissue formation process. It enables the arrangement of a structured fibrous tissue across the entire defect, which acts as a secondary supporting network for cells. Mineralization can then initiate along the fibrous network, resulting in bone ingrowth into a critical-sized defect, although not in complete bridging of the defect. The fibrous network morphology, which in turn is guided by the scaffold architecture, influences the microstructure of the newly formed bone. These results allow a deeper understanding of the mode of mineral tissue formation and the way this is influenced by the scaffold architecture. © 2012 American Society for Bone and Mineral Research.

Scaffold-based tissue engineering: rationale for computer-aided design and solid free-form fabrication systems

Publisher: Elsevier BV

Date: 07-2004

DOI: 10.1016/J.TIBTECH.2004.05.005

Humanized bone facilitates prostate cancer metastasis and recapitulates therapeutic effects of zoledronic acid in vivo

Publisher: Springer Science and Business Media LLC

Date: 21-10-2019

DOI: 10.1038/S41413-019-0072-9

Abstract: Advanced prostate cancer (PCa) is known for its high prevalence to metastasize to bone, at which point it is considered incurable. Despite significant effort, there is no animal model capable of recapitulating the complexity of PCa bone metastasis. The humanized mouse model for PCa bone metastasis used in this study aims to provide a platform for the assessment of new drugs by recapitulating the human–human cell interactions relevant for disease development and progression. The humanized tissue-engineered bone construct (hTEBC) was created within NOD-scid IL2rg null (NSG) mice and was used for the study of experimental PC3-Luc bone metastases. It was confirmed that PC3-Luc cells preferentially grew in the hTEBC compared with murine bone. The translational potential of the humanized mouse model for PCa bone metastasis was evaluated with two clinically approved osteoprotective therapies, the non-species-specific bisphosphonate zoledronic acid (ZA) or the human-specific antibody Denosumab, both targeting Receptor Activator of Nuclear Factor Kappa-Β Ligand. ZA, but not Denosumab, significantly decreased metastases in hTEBCs, but not murine femora. These results highlight the importance of humanized models for the preclinical research on PCa bone metastasis and indicate the potential of the bioengineered mouse model to closely mimic the metastatic cascade of PCa cells to human bone. Eventually, it will enable the development of new effective antimetastatic treatments.

Electrospinning writing with molten poly (ε-caprolactone) from different directions – Examining the effects of gravity

Publisher: Elsevier BV

Date: 04-2018

DOI: 10.1016/J.MATLET.2017.12.079

Fabrication of 3D chitosan–hydroxyapatite scaffolds using a robotic dispensing system

Publisher: Elsevier BV

Date: 05-2002

DOI: 10.1016/S0928-4931(02)00010-3

New mechanistic insights of integrin β1 in breast cancer bone colonization

Publisher: Impact Journals, LLC

Date: 15-11-2014

DOI: 10.18632/ONCOTARGET.2788

Abstract: Bone metastasis is a frequent and life-threatening complication of breast cancer. The molecular mechanisms supporting the establishment of breast cancer cells in the skeleton are still not fully understood, which may be attributed to the lack of suitable models that interrogate interactions between human breast cancer cells and the bone microenvironment. Although it is well-known that integrins mediate adhesion of malignant cells to bone extracellular matrix, their role during bone colonization remains unclear. Here, the role of β1 integrins in bone colonization was investigated using tissue-engineered humanized in vitro and in vivo bone models. In vitro, bone-metastatic breast cancer cells with suppressed integrin β1 expression showed reduced attachment, spreading, and migration within human bone matrix compared to control cells. Cell proliferation in vitro was not affected by β1 integrin knockdown, yet tumor growth in vivo within humanized bone microenvironments was significantly inhibited upon β1 integrin suppression, as revealed by quantitative in/ex vivo fluorescence imaging and histological analysis. Tumor cells invaded bone marrow spaces in the humanized bone and formed osteolytic lesions osteoclastic bone resorption was, however, not reduced by β1 integrin knockdown. Taken together, we demonstrate that β1 integrins have a pivotal role in bone colonization using unique tissue-engineered humanized bone models.

Custom-made composite scaffolds for segmental defect repair in long bones

Publisher: Springer Science and Business Media LLC

Date: 07-12-2010

DOI: 10.1007/S00264-010-1146-X

Multiphasic construct studied in an ectopic osteochondral defect model

Publisher: The Royal Society

Date: 06-06-2014

DOI: 10.1098/RSIF.2014.0184

Abstract: In vivo osteochondral defect models predominantly consist of small animals, such as rabbits. Although they have an advantage of low cost and manageability, their joints are smaller and more easily healed compared with larger animals or humans. We hypothesized that osteochondral cores from large animals can be implanted subcutaneously in rats to create an ectopic osteochondral defect model for routine and high-throughput screening of multiphasic scaffold designs and/or tissue-engineered constructs (TECs). Bovine osteochondral plugs with 4 mm diameter osteochondral defect were fitted with novel multiphasic osteochondral grafts composed of chondrocyte-seeded alginate gels and osteoblast-seeded polycaprolactone scaffolds, prior to being implanted in rats subcutaneously with bone morphogenic protein-7. After 12 weeks of in vivo implantation, histological and micro-computed tomography analyses demonstrated that TECs are susceptible to mineralization. Additionally, there was limited bone formation in the scaffold. These results suggest that the current model requires optimization to facilitate robust bone regeneration and vascular infiltration into the defect site. Taken together, this study provides a proof-of-concept for a high-throughput osteochondral defect model. With further optimization, the presented hybrid in vivo model may address the growing need for a cost-effective way to screen osteochondral repair strategies before moving to large animal preclinical trials.

Publisher's note-Correction

Publisher: Elsevier BV

Date: 07-2008

DOI: 10.1016/J.JBIOMECH.2008.04.036

Biofabricated soft network composites for cartilage tissue engineering

Publisher: IOP Publishing

Date: 12-05-2017

DOI: 10.1088/1758-5090/AA6B15

Abstract: Articular cartilage from a material science point of view is a soft network composite that plays a critical role in load-bearing joints during dynamic loading. Its composite structure, consisting of a collagen fiber network and a hydrated proteoglycan matrix, gives rise to the complex mechanical properties of the tissue including viscoelasticity and stress relaxation. Melt electrospinning writing allows the design and fabrication of medical grade polycaprolactone (mPCL) fibrous networks for the reinforcement of soft hydrogel matrices for cartilage tissue engineering. However, these fiber-reinforced constructs underperformed under dynamic and prolonged loading conditions, suggesting that more targeted design approaches and material selection are required to fully exploit the potential of fibers as reinforcing agents for cartilage tissue engineering. In the present study, we emulated the proteoglycan matrix of articular cartilage by using highly negatively charged star-shaped poly(ethylene glycol)/heparin hydrogel (sPEG/Hep) as the soft matrix. These soft hydrogels combined with mPCL melt electrospun fibrous networks exhibited mechanical anisotropy, nonlinearity, viscoelasticity and morphology analogous to those of their native counterpart, and provided a suitable microenvironment for in vitro human chondrocyte culture and neocartilage formation. In addition, a numerical model using the p-version of the finite element method (p-FEM) was developed in order to gain further insights into the deformation mechanisms of the constructs in silico, as well as to predict compressive moduli. To our knowledge, this is the first study presenting cartilage tissue-engineered constructs that capture the overall transient, equilibrium and dynamic biomechanical properties of human articular cartilage.

A road map for a tissue engineering concept for restoring structure and function after limb loss

Publisher: Springer Science and Business Media LLC

Date: 02-10-2013

DOI: 10.1007/S10856-013-5049-4

The influence of cellular source on periodontal regeneration using calcium phosphate coated polycaprolactone scaffold supported cell sheets

Publisher: Elsevier BV

Date: 2014

DOI: 10.1016/J.BIOMATERIALS.2013.09.074

Abstract: Cell-based therapy is considered a promising approach to achieving predictable periodontal regeneration. In this study, the regenerative potential of cell sheets derived from different parts of the periodontium (gingival connective tissue, alveolar bone and periodontal ligament) were investigated in an athymic rat periodontal defect model. Periodontal ligament (PDLC), alveolar bone (ABC) and gingival margin-derived cells (GMC) were obtained from human donors. The osteogenic potential of the primary cultures was demonstrated in vitro. Cell sheets supported by a calcium phosphate coated melt electrospun polycaprolactone (CaP-PCL) scaffold were transplanted to denuded root surfaces in surgically created periodontal defects, and allowed to heal for 1 and 4 weeks. The CaP-PCL scaffold alone was able to promote alveolar bone formation within the defect after 4 weeks. The addition of ABC and PDLC sheets resulted in significant periodontal attachment formation. The GMC sheets did not promote periodontal regeneration on the root surface and inhibited bone formation within the CaP-PCL scaffold. In conclusion, the combination of either PDLC or ABC sheets with a CaP-PCL scaffold could promote periodontal regeneration, but ABC sheets were not as effective as PDLC sheets in promoting new attachment formation.

Additive Biomanufacturing: An Advanced Approach for Periodontal Tissue Regeneration

Publisher: Springer Science and Business Media LLC

Date: 29-07-2016

DOI: 10.1007/S10439-016-1687-2

High performance additive manufactured scaffolds for bone tissue engineering application

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1SM05793F

The Concept of Scaffold-Guided Bone Regeneration for the Treatment of Long Bone Defects: Current Clinical Application and Future Perspective

Publisher: MDPI AG

Date: 27-06-2023

DOI: 10.3390/JFB14070341

Abstract: The treatment of bone defects remains a challenging clinical problem with high reintervention rates, morbidity, and resulting significant healthcare costs. Surgical techniques are constantly evolving, but outcomes can be influenced by several parameters, including the patient’s age, comorbidities, systemic disorders, the anatomical location of the defect, and the surgeon’s preference and experience. The most used therapeutic modalities for the regeneration of long bone defects include distraction osteogenesis (bone transport), free vascularized fibular grafts, the Masquelet technique, allograft, and (arthroplasty with) mega-prostheses. Over the past 25 years, three-dimensional (3D) printing, a breakthrough layer-by-layer manufacturing technology that produces final parts directly from 3D model data, has taken off and transformed the treatment of bone defects by enabling personalized therapies with highly porous 3D-printed implants tailored to the patient. Therefore, to reduce the morbidities and complications associated with current treatment regimens, efforts have been made in translational research toward 3D-printed scaffolds to facilitate bone regeneration. Three-dimensional printed scaffolds should not only provide osteoconductive surfaces for cell attachment and subsequent bone formation but also provide physical support and containment of bone graft material during the regeneration process, enhancing bone ingrowth, while simultaneously, orthopaedic implants supply mechanical strength with rigid, stable external and/or internal fixation. In this perspective review, we focus on elaborating on the history of bone defect treatment methods and assessing current treatment approaches as well as recent developments, including existing evidence on the advantages and disadvantages of 3D-printed scaffolds for bone defect regeneration. Furthermore, it is evident that the regulatory framework and organization and financing of evidence-based clinical trials remains very complex, and new challenges for non-biodegradable and biodegradable 3D-printed scaffolds for bone regeneration are emerging that have not yet been sufficiently addressed, such as guideline development for specific surgical indications, clinically feasible design concepts for needed multicentre international preclinical and clinical trials, the current medico-legal status, and reimbursement. These challenges underscore the need for intensive exchange and open and honest debate among leaders in the field. This goal can be addressed in a well-planned and focused stakeholder workshop on the topic of patient-specific 3D-printed scaffolds for long bone defect regeneration, as proposed in this perspective review.

THE BIOMEDICAL APPLICATIONS OF COMPUTED TOMOGRAPHY

Publisher: World Scientific Publishing Company

Date: 12-2007

DOI: 10.1142/9789812770042_0006

Melt Electrospinning Writing of Highly Ordered Large Volume Scaffold Architectures

Publisher: Wiley

Date: 10-04-2018

DOI: 10.1002/ADMA.201706570

Abstract: The additive manufacturing of highly ordered, micrometer-scale scaffolds is at the forefront of tissue engineering and regenerative medicine research. The fabrication of scaffolds for the regeneration of larger tissue volumes, in particular, remains a major challenge. A technology at the convergence of additive manufacturing and electrospinning-melt electrospinning writing (MEW)-is also limited in thickness/volume due to the accumulation of excess charge from the deposited material repelling and hence, distorting scaffold architectures. The underlying physical principles are studied that constrain MEW of thick, large volume scaffolds. Through computational modeling, numerical values variable working distances are established respectively, which maintain the electrostatic force at a constant level during the printing process. Based on the computational simulations, three voltage profiles are applied to determine the maximum height (exceeding 7 mm) of a highly ordered large volume scaffold. These thick MEW scaffolds have fully interconnected pores and allow cells to migrate and proliferate. To the best of the authors knowledge, this is the first study to report that z-axis adjustment and increasing the voltage during the MEW process allows for the fabrication of high-volume scaffolds with uniform morphologies and fiber diameters.

Multi-parametric hydrogels support 3D invitro bioengineered microenvironment models of tumour angiogenesis

Publisher: Elsevier BV

Date: 06-2015

DOI: 10.1016/J.BIOMATERIALS.2015.02.124

Abstract: Tumour microenvironment greatly influences the development and metastasis of cancer progression. The development of three dimensional (3D) culture models which mimic that displayed in vivo can improve cancer biology studies and accelerate novel anticancer drug screening. Inspired by a systems biology approach, we have formed 3D in vitro bioengineered tumour angiogenesis microenvironments within a glycosaminoglycan-based hydrogel culture system. This microenvironment model can routinely recreate breast and prostate tumour vascularisation. The multiple cell types cultured within this model were less sensitive to chemotherapy when compared with two dimensional (2D) cultures, and displayed comparative tumour regression to that displayed in vivo. These features highlight the use of our in vitro culture model as a complementary testing platform in conjunction with animal models, addressing key reduction and replacement goals of the future. We anticipate that this biomimetic model will provide a platform for the in-depth analysis of cancer development and the discovery of novel therapeutic targets.

BMP delivery complements the guiding effect of scaffold architecture without altering bone microstructure in critical-sized long bone defects: A multiscale analysis

Publisher: Elsevier BV

Date: 09-2015

DOI: 10.1016/J.ACTBIO.2015.05.015

Abstract: Scaffold architecture guides bone formation. However, in critical-sized long bone defects additional BMP-mediated osteogenic stimulation is needed to form clinically relevant volumes of new bone. The hierarchical structure of bone determines its mechanical properties. Yet, the micro- and nanostructure of BMP-mediated fast-forming bone has not been compared with slower regenerating bone without BMP. We investigated the combined effects of scaffold architecture (physical cue) and BMP stimulation (biological cue) on bone regeneration. It was hypothesized that a structured scaffold directs tissue organization through structural guidance and load transfer, while BMP stimulation accelerates bone formation without altering the microstructure at different length scales. BMP-loaded medical grade polycaprolactone-tricalcium phosphate scaffolds were implanted in 30mm tibial defects in sheep. BMP-mediated bone formation after 3 and 12 months was compared with slower bone formation with a scaffold alone after 12 months. A multiscale analysis based on microcomputed tomography, histology, polarized light microscopy, backscattered electron microscopy, small angle X-ray scattering and nanoindentation was used to characterize bone volume, collagen fiber orientation, mineral particle thickness and orientation, and local mechanical properties. Despite different observed kinetics in bone formation, similar structural properties on a microscopic and sub-micron level seem to emerge in both BMP-treated and scaffold only groups. The guiding effect of the scaffold architecture is illustrated through structural differences in bone across different regions. In the vicinity of the scaffold increased tissue organization is observed at 3 months. Loading along the long bone axis transferred through the scaffold defines bone micro- and nanostructure after 12 months.

Via precise interface engineering towards bioinspired composites with improved 3D printing processability and mechanical properties

Publisher: Royal Society of Chemistry (RSC)

Date: 2017

DOI: 10.1039/C7TB00165G

Abstract: Precise interface engineering in inorganic–organic hybrid materials enhances both the elastic moduli and toughness of a biodegradable composite, which is of relevance for load-bearing applications in bone tissue engineering.

Data for accelerated degradation of calcium phosphate surface-coated polycaprolactone and polycaprolactone/bioactive glass composite scaffolds

Publisher: Elsevier BV

Date: 06-2016

DOI: 10.1016/J.DIB.2016.01.023

Investigation of microstructural features in regenerating bone using micro computed tomography

Publisher: Springer Science and Business Media LLC

Date: 04-2004

DOI: 10.1023/B:JMSM.0000021133.48661.62

Abstract: We illustrate some of the uses of micro-computed tomography (micro-CT) to study tissue-engineered bone using a micro-CT facility for imaging and visualizing biomaterials in three dimensions (3-D). The micro-CT is capable of acquiring 3D X-ray CT images made up of 2000(3) voxels on specimens up to 5 cm in extent with resolutions down to 2 microm. This allows the 3-D structure of tissue-engineered materials to be imaged across orders of magnitude in resolution. This capability is used to examine an explanted, tissue-engineered bone material based on a polycaprolactone scaffold and autologous bone marrow cells. Imaging of the tissue-engineered bone at a scale of 1 cm and resolutions of 10 microm allows one to visualize the complex ingrowth of bone into the polymer scaffold. From a theoretical viewpoint the voxel data may also be used to calculate expected mechanical properties of the tissue-engineered implant. These observations illustrate the benefits of tomography over traditional techniques for the characterization of bone morphology and interconnectivity. As the method is nondestructive it can perform a complimentary role to current histomorphometric techniques.

Immunogold FIB‐SEM: Combining Volumetric Ultrastructure Visualization with 3D Biomolecular Analysis to Dissect Cell–Environment Interactions

Publisher: Wiley

Date: 13-06-2019

DOI: 10.1002/ADMA.201900488

Engineering tubular bone constructs

Publisher: Elsevier BV

Date: 2007

DOI: 10.1016/J.JBIOMECH.2007.02.017

Abstract: Cell-sheet techniques have been proven effective in various soft tissue engineering applications. In this experiment, we investigated the feasibility of bone tissue engineering using a hybrid of mesenchymal stem cell (MSC) sheets and PLGA meshes. Porcine MSCs were cultured to a thin layer of cell sheets via osteogenic induction. Tube-like long bones were constructed by wrapping the cell sheet on to PLGA meshes resulting in constructs which could be cultured in spinner flasks, prior to implantation in nude rats. Our results showed that the sheets were composed of viable cells and dense matrix with a thickness of about 80-120 microm, mineral deposition was also observed in the sheet. In vitro cultures demonstrated calcified cartilage-like tissue formation and most PLGA meshes were absorbed during the 8-week culture period. In vivo experiments revealed that dense mineralized tissue was formed in subcutaneous sites and the 8-week plants shared similar micro-CT characteristics with native bone. The neo tissue demonstrated histological markers for both bone and cartilage, indicating that the bone formation pathway in constructs was akin to endochondral ossification, with the residues of PLGA having an effect on the neo tissue organization and formation. These results indicate that cell-sheet approaches in combination with custom-shaped scaffolds have potential in producing bone tissue.

A collagen network phase improves cell seeding of open-pore structure scaffolds under perfusion

Publisher: Hindawi Limited

Date: 17-11-2011

DOI: 10.1002/TERM.506

Abstract: Scaffolds with open-pore morphologies offer several advantages in cell-based tissue engineering, but their use is limited by a low cell-seeding efficiency. We hypothesized that inclusion of a collagen network as filling material within the open-pore architecture of polycaprolactone-tricalcium phosphate (PCL-TCP) scaffolds increases human bone marrow stromal cells (hBMSCs) seeding efficiency under perfusion and in vivo osteogenic capacity of the resulting constructs. PCL-TCP scaffolds, rapid prototyped with a honeycomb-like architecture, were filled with a collagen gel and subsequently lyophilized, with or without final crosslinking. Collagen-free scaffolds were used as controls. The seeding efficiency was assessed after overnight perfusion of expanded hBMSCs directly through the scaffold pores using a bioreactor system. By seeding and culturing freshly harvested hBMSCs under perfusion for 3 weeks, the osteogenic capacity of generated constructs was tested by ectopic implantation in nude mice. The presence of the collagen network, independently of the crosslinking process, significantly increased the cell seeding efficiency (2.5-fold), and reduced the loss of clonogenic cells in the supernatant. Although no implant generated frank bone tissue, possibly due to the mineral distribution within the scaffold polymer phase, the presence of a non-crosslinked collagen phase led to in vivo formation of scattered structures of dense osteoids. Our findings verify that the inclusion of a collagen network within open morphology porous scaffolds improves cell retention under perfusion seeding. In the context of cell-based therapies, collagen-filled porous scaffolds are expected to yield superior cell utilization, and could be combined with perfusion-based bioreactor devices to streamline graft manufacture.

Polymeric Biomaterials

Publisher: CRC Press

Date: 17-01-2013

DOI: 10.1201/B13757

Endogenous musculoskeletal tissue regeneration

Publisher: Springer Science and Business Media LLC

Date: 24-02-2012

DOI: 10.1007/S00441-012-1357-0

A 3D tumor microenvironment regulates cell proliferation, peritoneal growth and expression patterns

Publisher: Elsevier BV

Date: 2019

DOI: 10.1016/J.BIOMATERIALS.2018.10.014

Abstract: Peritoneal invasion through the mesothelial cell layer is a hallmark of ovarian cancer metastasis. Using tissue engineering technologies, we recreated an ovarian tumor microenvironment replicating this aspect of disease progression. Ovarian cancer cell-laden hydrogels were combined with mesothelial cell-layered melt electrospun written scaffolds and characterized with proliferation and transcriptomic analyses and used as intraperitoneal xenografts. Here we show increased cancer cell proliferation in these 3D co-cultures, which we validated using patient-derived cells and linked to peritoneal tumor growth in vivo. Transcriptome-wide expression analysis identified IGFBP7, PTGS2, VEGFC and FGF2 as bidirectional factors deregulated in 3D co-cultures compared to 3D mono-cultures, which we confirmed by immunohistochemistry of xenograft and patient-derived tumor tissues and correlated with overall and progression-free survival. These factors were further increased upon expression of kallikrein-related proteases. This clinically predictive model allows us to mimic the complexity and processes of the metastatic disease that may lead to therapies that protect from peritoneal invasion or delay the development of metastasis.

Engineered silk fibroin protein 3D matrices for in vitro tumor model

Publisher: Elsevier BV

Date: 03-2011

DOI: 10.1016/J.BIOMATERIALS.2010.11.052

Abstract: 3D in vitro model systems that are able to mimic the in vivo microenvironment are now highly sought after in cancer research. Antheraea mylitta silk fibroin protein matrices were investigated as potential biomaterial for in vitro tumor modeling. We compared the characteristics of MDA-MB-231 cells on A. mylitta, Bombyx mori silk matrices, Matrigel, and tissue culture plates. The attachment and morphology of the MDA-MB-231 cell line on A. mylitta silk matrices was found to be better than on B. mori matrices and comparable to Matrigel and tissue culture plates. The cells grown in all 3D cultures showed more MMP-9 activity, indicating a more invasive potential. In comparison to B. mori fibroin, A. mylitta fibroin not only provided better cell adhesion, but also improved cell viability and proliferation. Yield coefficient of glucose consumed to lactate produced by cells on 3D A. mylitta fibroin was found to be similar to that of cancer cells in vivo. LNCaP prostate cancer cells were also cultured on 3D A. mylitta fibroin and they grew as clumps in long term culture. The results indicate that A. mylitta fibroin scaffold can provide an easily manipulated microenvironment system to investigate in idual factors such as growth factors and signaling peptides, as well as evaluation of anticancer drugs.

Microrobotics and MEMS‐Based Fabrication Techniques for Scaffold‐Based Tissue Engineering

Publisher: Wiley

Date: 20-06-2005

DOI: 10.1002/MABI.200400202

Abstract: Scaffold based tissue engineering strategies use cells, biomolecules and a scaffold to promote the repair and regeneration of tissues. Although scaffold-based tissue engineering approaches are being actively developed, most are still experimental, and it is not yet clear what defines an ideal scaffold/cell construct. Solid free form fabrication (SFF) techniques can precisely control matrix architecture (size, shape, interconnectivity, branching, geometry and orientation). The SFF methods enable the fabrication of scaffolds with various designs and material compositions, thus providing a control of mechanical properties, biological effects and degradation kinetics. This paper reviews the application of micro-robotics and MEMS-based fabrication techniques for scaffold design and fabrication. It also presents a novel robotic technique to fabricate scaffold/cell constructs for tissue engineering by the assembly of microscopic building blocks.

Scaffolds in tissue engineering bone and cartilage

Publisher: Elsevier

Date: 2000

DOI: 10.1016/B978-008045154-1.50021-6

Scaffold design and fabrication technologies for engineering tissues — state of the art and future perspectives

Publisher: Informa UK Limited

Date: 2001

DOI: 10.1163/156856201744489

Abstract: Today, tissue engineers are attempting to engineer virtually every human tissue. Potential tissue-engineered products include cartilage, bone, heart valves, nerves, muscle, bladder, liver, etc. Tissue engineering techniques generally require the use of a porous scaffold, which serves as a three-dimensional template for initial cell attachment and subsequent tissue formation both in vitro and in vivo. The scaffold provides the necessary support for cells to attach, proliferate, and maintain their differentiated function. Its architecture defines the ultimate shape of the new grown soft or hard tissue. In the early days of tissue engineering, clinically established materials such as collagen and polyglycolide were primarily considered as the material of choice for scaffolds. The challenge for more advanced scaffold systems is to arrange cells/tissue in an appropriate 3D configuration and present molecular signals in an appropriate spatial and temporal fashion so that the in idual cells will grow and form the desired tissue structures--and do so in a way that can be carried out reproducibly, economically, and on a large scale. This paper is not intended to provide a general review of tissue engineering, but specifically concentrate on the design and processing of synthetic polymeric scaffolds. The material properties and design requirements are discussed. An overview of the various fabrication techniques of scaffolds is presented, beginning with the basic and conventional techniques to the more recent, novel methods that combine both scaffold design and fabrication capabilities.

Scaffold design and fabrication

Publisher: Elsevier

Date: 2023

DOI: 10.1016/B978-0-12-824459-3.00011-1

Quo Vadis Breast Tissue Engineering?

Publisher: Elsevier BV

Date: 04-2016

DOI: 10.1016/J.EBIOM.2016.03.044

Fabrication and Characterization of Decellularized Periodontal Ligament Cell Sheet Constructs

Publisher: Springer New York

Date: 07-12-2016

DOI: 10.1007/978-1-4939-6685-1_23

Abstract: Decellularized tissue-engineered constructs have the potential to promote regeneration by providing a biomimetic extracellular matrix that directs tissue-specific regeneration when implanted in situ. Recently, the use of cell sheets has shown promising results in promoting periodontal regeneration. Here, we describe the fabrication of decellularized periodontal cell sheets with intact extracellular matrix structural and biological properties. Melt electro spun polycaprolactone (PCL) scaffolds are used as a carrier for the inherently fragile cell sheets, to provide support during the processes of decellularization. An optimized decellularization method is outlined using perfusion with a combination of NH

Initial design and physical characterization of a polymeric device for osmosis-driven delayed burst delivery of vaccines

Publisher: Wiley

Date: 18-06-2015

DOI: 10.1002/BIT.25593

Abstract: Achieving the combination of delayed and immediate release of a vaccine from a delivery device without applying external triggers remains elusive in implementing single administration vaccination strategies. Here a means of vaccine delivery is presented, which exploits osmosis to trigger delayed burst release of an active compound. Poly(ε-caprolactone) capsules of 2 mm diameter were prepared by dip-coating, and their burst pressure and release characteristics were evaluated. Burst pressures (in bar) increased with wall thickness (t in mm) following Pburst = 131(.) t + 3(.) 4 (R(2) = 0.93). Upon immersion in PBS, glucose solution-filled capsules burst after 8.7 ± 2.9 days. Copolymers of hydrophobic ε -caprolactone and hydrophilic polyethylene glycol were synthesized and their physico-chemical properties were assessed. With increasing hydrophilic content, the copolymer capsules showed increased water uptake rates and maximum weight increase, while the burst release was earlier: 5.6 ± 2.0 days and 1.9 ± 0.2 days for 5 and 10 wt% polyethylene glycol, respectively. The presented approach enables the reproducible preparation of capsules with high versatility in materials and properties, while these vaccine delivery vehicles can be prepared separately from, and independently of the active compound.

Fabrication using a rapid prototyping system and in vitro characterization of PEG-PCL-PLA scaffolds for tissue engineering

Publisher: Informa UK Limited

Date: 2005

DOI: 10.1163/156856205774576709

Abstract: In the field of tissue engineering new polymers are needed to fabricate scaffolds with specific properties depending on the targeted tissue. This work aimed at designing and developing a 3D scaffold with variable mechanical strength, fully interconnected porous network, controllable hydrophilicity and degradability. For this, a desktop-robot-based melt-extrusion rapid prototyping technique was applied to a novel tri-block co-polymer, namely poly(ethylene glycol)-block-poly(epsilon-caprolactone)-block-poly(DL-lactide), PEG-PCL-P(DL)LA. This co-polymer was melted by electrical heating and directly extruded out using computer-controlled rapid prototyping by means of compressed purified air to build porous scaffolds. Various lay-down patterns (0/30/60/90/120/150 degrees, 0/45/90/135 degrees, 0/60/120 degrees and 0/90 degrees) were produced by using appropriate positioning of the robotic control system. Scanning electron microscopy and micro-computed tomography were used to show that 3D scaffold architectures were honeycomb-like with completely interconnected and controlled channel characteristics. Compression tests were performed and the data obtained agreed well with the typical behavior of a porous material undergoing deformation. Preliminary cell response to the as-fabricated scaffolds has been studied with primary human fibroblasts. The results demonstrated the suitability of the process and the cell biocompatibility of the polymer, two important properties among the many required for effective clinical use and efficient tissue-engineering scaffolding.

Gerüstträgerbasiertes Knochen-Tissue-Engineering

Publisher: Springer Science and Business Media LLC

Date: 19-07-2017

DOI: 10.1007/S00132-017-3444-0

Abstract: Tissue engineering provides the possibility of regenerating damaged or lost osseous structures without the need for permanent implants. Within this context, biodegradable and bioresorbable scaffolds can provide structural and biomechanical stability until the body's own tissue can take over their function. Additive biomanufacturing makes it possible to design the scaffold's architectural characteristics to specifically guide tissue formation and regeneration. Its nano-, micro-, and macro-architectural properties can be tailored to ensure vascularization, oxygenation, nutrient supply, waste exchange, and eventually ossification not only in its periphery but also in its center, which is not in direct contact with osteogenic elements of the surrounding healthy tissue. In this article we provide an overview about our conceptual design and process of the clinical translation of scaffold-based bone tissue engineering applications.

Tissue engineering and regenerative medicine in musculoskeletal oncology

Publisher: Springer Science and Business Media LLC

Date: 26-08-2016

DOI: 10.1007/S10555-016-9635-Z

Abstract: Currently used surgical techniques to reconstruct tissue defects after resection of musculoskeletal tumours are associated with high complication rates. This drives a strong demand for innovative therapeutic concepts that are able to improve the clinical outcomes of patients suffering from bone and soft tissue tumours. Tissue engineering and regenerative medicine (TE&RM) provides a technology platform based on biochemical, molecular, cellular and biomaterials modules to selectively direct tissue healing processes for improved defect regeneration. At the same time, precautionary measures have to be taken when these instruments are used in cancer patients to prevent any promotion of tumour growth or metastatic spread. On the other hand, several innovative TE&RM tools are being developed such as multi-functionalized biomaterials, drug-delivering nanomaterials or genetically engineered stem cells that per se have the potential to mediate anti-cancer effects, act synergistically with currently used chemotherapeutics and/or radiotherapy regimens and reduce their side effects. Recently, scientists became conscious that TE&RM strategies may not only be utilized to advance contemporary tissue reconstruction techniques but also to develop personalized diagnostic tools and clinically relevant disease models for cancer patients. Eventually, prospective randomized clinical trials combined with comparative outcome analyses are a conditio sine qua non to shape the benefits of personalized regenerative therapies for the standardized management of patients with musculoskeletal tumours.

Simultaneous biaxial drawing of poly (ϵ-caprolactone) films

Publisher: Elsevier BV

Date: 07-2000

DOI: 10.1016/S0032-3861(99)00760-0

Bone Tissue Engineering

Publisher: WORLD SCIENTIFIC

Date: 12-2010

DOI: 10.1142/9789812833303_0006

Automated microassembly of tissue engineering scaffold

Publisher: IEEE

Date: 05-2010

DOI: 10.1109/ROBOT.2010.5509687

The challenge of establishing preclinical models for segmental bone defect research

Publisher: Elsevier BV

Date: 04-2009

DOI: 10.1016/J.BIOMATERIALS.2008.12.050

Abstract: A considerable number of international research groups as well as commercial entities work on the development of new bone grafting materials, carriers, growth factors and specifically tissue-engineered constructs for bone regeneration. They are strongly interested in evaluating their concepts in highly reproducible large segmental defects in preclinical and large animal models. To allow comparison between different studies and their outcomes, it is essential that animal models, fixation devices, surgical procedures and methods of taking measurements are well standardized to produce reliable data pools and act as a base for further directions to orthopaedic and tissue engineering developments, specifically translation into the clinic. In this leading opinion paper, we aim to review and critically discuss the different large animal bone defect models reported in the literature. We conclude that most publications provide only rudimentary information on how to establish relevant preclinical segmental bone defects in large animals. Hence, we express our opinion on methodologies to establish preclinical critically sized, segmental bone defect models used in past research with reference to surgical techniques, fixation methods and postoperative management focusing on tibial fracture and segmental defect models.

Multiphasic Scaffolds for Periodontal Tissue Engineering

Publisher: SAGE Publications

Date: 19-08-2014

DOI: 10.1177/0022034514544301

Abstract: For a successful clinical outcome, periodontal regeneration requires the coordinated response of multiple soft and hard tissues (periodontal ligament, gingiva, cementum, and bone) during the wound-healing process. Tissue-engineered constructs for regeneration of the periodontium must be of a complex 3-dimensional shape and adequate size and demonstrate biomechanical stability over time. A critical requirement is the ability to promote the formation of functional periodontal attachment between regenerated alveolar bone, and newly formed cementum on the root surface. This review outlines the current advances in multiphasic scaffold fabrication and how these scaffolds can be combined with cell- and growth factor–based approaches to form tissue-engineered constructs capable of recapitulating the complex temporal and spatial wound-healing events that will lead to predictable periodontal regeneration. This can be achieved through a variety of approaches, with promising strategies characterized by the use of scaffolds that can deliver and stabilize cells capable of cementogenesis onto the root surface, provide biomechanical cues that encourage perpendicular alignment of periodontal fibers to the root surface, and provide osteogenic cues and appropriate space to facilitate bone regeneration. Progress on the development of multiphasic constructs for periodontal tissue engineering is in the early stages of development, and these constructs need to be tested in large animal models and, ultimately, human clinical trials.

Mineralization capacity of Runx2/Cbfa1-genetically engineered fibroblasts is scaffold dependent

Publisher: Elsevier BV

Date: 11-2006

DOI: 10.1016/J.BIOMATERIALS.2006.06.019

Abstract: Development of tissue-engineered constructs for skeletal regeneration of large critical-sized defects requires the identification of a sustained mineralizing cell source and careful optimization of scaffold architecture and surface properties. We have recently reported that Runx2-genetically engineered primary dermal fibroblasts express a mineralizing phenotype in monolayer culture, highlighting their potential as an autologous osteoblastic cell source which can be easily obtained in large quantities. The objective of the present study was to evaluate the osteogenic potential of Runx2-expressing fibroblasts when cultured in vitro on three commercially available scaffolds with ergent properties: fused deposition-modeled polycaprolactone (PCL), gas-foamed polylactide-co-glycolide (PLGA), and fibrous collagen disks. We demonstrate that the mineralization capacity of Runx2-engineered fibroblasts is scaffold dependent, with collagen foams exhibiting ten-fold higher mineral volume compared to PCL and PLGA matrices. Constructs were differentially colonized by genetically modified fibroblasts, but scaffold-directed changes in DNA content did not correlate with trends in mineral deposition. Sustained expression of Runx2 upregulated osteoblastic gene expression relative to unmodified control cells, and the magnitude of this expression was modulated by scaffold properties. Histological analyses revealed that matrix mineralization co-localized with cellular distribution, which was confined to the periphery of fibrous collagen and PLGA sponges and around the circumference of PCL microfilaments. Finally, FTIR spectroscopy verified that mineral deposits within all Runx2-engineered scaffolds displayed the chemical signature characteristic of carbonate-containing, poorly crystalline hydroxyapatite. These results highlight the important effect of scaffold properties on the capacity of Runx2-expressing primary dermal fibroblasts to differentiate into a mineralizing osteoblastic phenotype for bone tissue engineering applications.

Porcine bone marrow stromal cell differentiation on heparin-adsorbed poly(e-caprolactone)-tricalcium phosphate-collagen scaffolds

Publisher: Elsevier BV

Date: 11-2009

DOI: 10.1016/J.ACTBIO.2009.05.015

Abstract: We evaluate the potential of heparin as a substrate component for the fabrication of bone tissue engineering constructs using poly(e-caprolactone)-tricalcium phosphate-collagen type I (PCL-TCP-Col) three-dimensional (3-D) scaffolds. First we explored the ability of porcine bone marrow precursor cells (MPCs) to differentiate down both the adipogenic and osteogenic pathways within 2-D culture systems, with positive results confirmed by Oil-Red-O and Alizarin Red staining, respectively. Secondly, we examined the influence of heparin on the interaction and behaviour of MPCs when seeded onto PCL-TCP-Col 3-D scaffolds, followed by their induction into the osteogenic lineage. Our 3-D findings suggest that cell metabolism and proliferation increased between days 1 and 14, with deposition of extracellular matrix also observed up to 28 days. However, no noticeable difference could be detected in the extent of osteogenesis for PCL-TCP-Col scaffolds groups with the addition of heparin compared to identical control scaffolds without the addition of heparin.

Meso-Endothelial Bipotent Progenitors from Human Placenta Display Distinct Molecular and Cellular Identity

Publisher: Elsevier BV

Date: 03-2018

DOI: 10.1016/J.STEMCR.2018.01.011

Evaluation of polycaprolactone scaffold degradation for 6 months in vitro and in vivo

Publisher: Wiley

Date: 21-07-2008

DOI: 10.1002/JBM.A.32052

Abstract: The use of polycaprolactone (PCL) as a biomaterial, especially in the fields of drug delivery and tissue engineering, has enjoyed significant growth. Understanding how such a device or scaffold eventually degrades in vivo is paramount as the defect site regenerates and remodels. Degradation studies of three-dimensional PCL and PCL-based composite scaffolds were conducted in vitro (in phosphate buffered saline) and in vivo (rabbit model). Results up to 6 months are reported. All s les recorded virtually no molecular weight changes after 6 months, with a maximum mass loss of only about 7% from the PCL-composite scaffolds degraded in vivo, and a minimum of 1% from PCL scaffolds. Overall, crystallinity increased slightly because of the effects of polymer recrystallization. This was also a contributory factor for the observed stiffness increment in some of the s les, while only the PCL-composite scaffold registered a decrease. Histological examination of the in vivo s les revealed good biocompatibility, with no adverse host tissue reactions up to 6 months. Preliminary results of medical-grade PCL scaffolds, which were implanted for 2 years in a critical-sized rabbit calvarial defect site, are also reported here and support our scaffold design goal for gradual and late molecular weight decreases combined with excellent long-term biocompatibility and bone regeneration.

Coating of biomaterial scaffolds with the collagen-mimetic peptide GFOGER for bone defect repair

Publisher: Elsevier BV

Date: 03-2010

DOI: 10.1016/J.BIOMATERIALS.2009.12.008

A histomorphometric assessment of collagen‐stabilized anorganic bovine bone mineral in maxillary sinus augmentation – a randomized controlled trial in sheep

Publisher: Wiley

Date: 03-07-2015

DOI: 10.1111/CLR.12652

Abstract: To histomorphometrically compare the use of collagen-stabilized anorganic bovine bone (ABBM-C) (test) to anorganic bovine bone + autogenous bone (ABBM + AB) (control) in maxillary sinus augmentation. Nine sheep underwent bilateral sinus augmentation. Each sinus was randomized to receive either control or test bone graft. Three animals were sacrificed at 8 weeks, and six animals were sacrificed at 16 weeks post-grafting. The 18 sinuses were processed for histomorphometry, which assessed the area fraction of new bone (%NB), residual graft (%RG) and soft tissue components (% STM), as well as graft particle osseointegration (% OI), within three zones equally distributed from the augmented sinus floor. At week 16, a significant increase in %NB was evident across all three zones in the control group when compared to week 8. A significantly greater %NB was evident in the control group when compared to the test group in zones 2 (P < 0.001) and 3 (P < 0.001). There was a significant increase in %OI in week 16 when compared to week 8 across all three zones in the control group (P < 0.001). %OI in the control group was significantly greater across all three zones when compared to the test group at week 16 (P < 0.001). Zone was found to be a significant main effect (P < 0.001) that was independent of time and treatment with decreasing %OI in distant zones. %RG did not significantly change with time for both groups. There was a significant reduction in %ST in week 16 when compared to week 8 across all three zones in the control group (P < 0.001). %ST in the test group was significantly greater across all zones when compared to the control group at week 16 (P < 0.001). Both groups exhibited very similar histomorphometric measurements in the zones proximal to the resident sinus wall. The % NB and % OI were greatest in the zones proximal to resident bony walls and gradually decreased as the distance from the proximal walls increased. There was greater % NB and % OI in the control group when compared to the test group in the distant zone.

A Polymerase Chain Reaction-Based Method for Isolating Clones from a Complimentary DNA Library in Sheep

Publisher: Mary Ann Liebert Inc

Date: 10-2014

DOI: 10.1089/TEN.TEC.2013.0099

Differences between in vitro viability and differentiation and in vivo bone-forming efficacy of human mesenchymal stem cells cultured on PCL-TCP scaffolds

Publisher: Elsevier BV

Date: 11-2010

DOI: 10.1016/J.BIOMATERIALS.2010.07.001

Abstract: Human mesenchymal stem cells (hMSCs) possess great therapeutic potential for the treatment of bone disease and fracture non-union. Too often however, in vitro evidence alone of the interaction between hMSCs and the biomaterial of choice is used as justification for continued development of the material into the clinic. Clearly for hMSC-based regenerative medicine to be successful for the treatment of orthopaedic trauma, it is crucial to transplant hMSCs with a suitable carrier that facilitates their survival, optimal proliferation and osteogenic differentiation in vitro and in vivo. This motivated us to evaluate the use of polycaprolactone-20% tricalcium phosphate (PCL-TCP) scaffolds produced by fused deposition modeling for the delivery of hMSCs. When hMSCs were cultured on the PCL-TCP scaffolds and imaged by a combination of phase contrast, scanning electron and confocal laser microscopy, we observed five distinct stages of colonization over a 21-day period that were characterized by cell attachment, spreading, cellular bridging, the formation of a dense cellular mass and the accumulation of a mineralized extracellular matrix when induced with osteogenic stimulants. Having established that PCL-TCP scaffolds are able to support hMSC proliferation and osteogenic differentiation, we next tested the in vivo efficacy of hMSC-loaded PCL-TCP scaffolds in nude rat critical-sized femoral defects. We found that fluorescently labeled hMSCs survived in the defect site for up to 3 weeks post-transplantation. However, only 50% of the femoral defects treated with hMSCs responded favorably as determined by new bone volume. As such, we show that verification of hMSC viability and differentiation in vitro is not sufficient to predict the efficacy of transplanted stem cells to consistently promote bone formation in orthotopic defects in vivo.

Influences of age and mechanical stability on volume, microstructure, and mineralization of the fracture callus during bone healing: Is osteoclast activity the key to age-related impaired healing?

Publisher: Elsevier BV

Date: 08-2010

DOI: 10.1016/J.BONE.2010.05.029

Abstract: Earlier studies have shown that the influence of fixation stability on bone healing diminishes with advanced age. The goal of this study was to unravel the relationship between mechanical stimulus and age on callus competence at a tissue level. Using 3D in vitro micro-computed tomography derived metrics, 2D in vivo radiography, and histology, we investigated the influences of age and varying fixation stability on callus size, geometry, microstructure, composition, remodeling, and vascularity. Compared were four groups with a 1.5-mm osteotomy gap in the femora of Sprague-Dawley rats: Young rigid (YR), Young semirigid (YSR), Old rigid (OR), Old semirigid (OSR). Hypothesis was that calcified callus microstructure and composition is impaired due to the influence of advanced age, and these in iduals would show a reduced response to fixation stabilities. Semirigid fixations resulted in a larger DeltaCSA (Callus cross-sectional area) compared to rigid groups. In vitro microCT analysis at 6 weeks postmortem showed callus bridging scores in younger animals to be superior than their older counterparts (p<0.01). Younger animals showed (i) larger callus strut thickness (p<0.001), (ii) lower perforation in struts (p<0.01), and (iii) higher mineralization of callus struts (p<0.001). Callus mineralization was reduced in young animals with semirigid fracture fixation but remained unaffected in the aged group. While stability had an influence, age showed none on callus size and geometry of callus. With no differences observed in relative osteoid areas in the callus ROI, old as well as semirigid fixated animals showed a higher osteoclast count (p<0.05). Blood vessel density was reduced in animals with semirigid fixation (p<0.05). In conclusion, in vivo monitoring indicated delayed callus maturation in aged in iduals. Callus bridging and callus competence (microstructure and mineralization) were impaired in in iduals with an advanced age. This matched with increased bone resorption due to higher osteoclast numbers. Varying fixator configurations in older in iduals did not alter the dominant effect of advanced age on callus tissue mineralization, unlike in their younger counterparts. Age-associated influences appeared independent from stability. This study illustrates the dominating role of osteoclastic activity in age-related impaired healing, while demonstrating the optimization of fixation parameters such as stiffness appeared to be less effective in influencing healing in aged in iduals.

Tissue Engineered Constructs for Periodontal Regeneration: Current Status and Future Perspectives

Publisher: Wiley

Date: 26-08-2018

DOI: 10.1002/ADHM.201800457

Abstract: The periodontium, consisting of gingiva, periodontal ligament, cementum, and alveolar bone, is a hierarchically organized tissue whose primary role is to provide physical and mechanical support to the teeth. Severe cases of periodontitis, an inflammatory condition initiated by an oral bacterial biofilm, can lead to significant destruction of soft and hard tissues of the periodontium and result in compromised dental function and aesthetics. Although current treatment approaches can limit the progression of the disease by controlling the inflammatory aspect, complete periodontal regeneration cannot be predictably achieved. Various tissue engineering approaches are investigated for their ability to control the critical temporo-spatial wound healing events that are essential for achieving periodontal regeneration. This paper reviews recent progress in the field of periodontal tissue engineering with an emphasis on advanced 3D multiphasic tissue engineering constructs (TECs) and provides a critical analysis of their regenerative potential and limitations. The review also elaborates on the future of periodontal tissue engineering, including scaffold customization for in idual periodontal defects, TEC's functionalization strategies for imparting enhanced bioactivity, periodontal ligament fiber guidance, and the utilization of chair-side regenerative solutions that can facilitate clinical translation.

Insight into characteristic features of cartilage growth plate as a physiological template for bone formation

Publisher: Wiley

Date: 10-10-2015

DOI: 10.1002/JBM.A.35575

Abstract: Cartilage growth plate is a natural template from both a biochemical and structural point of view and allows osteoblasts migration, proliferation, differentiation, and ultimately, bone formation. It is evolutionary adjusted to support bone formation within strictly defined spatial framework serving as an interesting model for studying more mechanistically aspects which might be important for specific scaffold-based bone tissue engineering strategies. Surprisingly little is known about the geometric features of this physiological template. To this purpose we analyzed cartilage growth plate from rat, mouse, and human costochondral junction and tibia. High-resolution X-ray tomography showed that pore size in the zone of provisional calcification was within 20 to 30 µm range and in the metaphysis in 35 to 50 µm range. The thickness of calcified longitudinal septa in zone of provisional calcification was 3 to 5 µm and in metaphysis 7 to 12 µm. The porosity varied from 84 to 88%. We observed that numerical values characteristic for cartilage growth plate were not significantly influenced by the species of origin, by the type of bone, or by age. In addition, electron microscopy of calcified fragments of longitudinal septa showed that the calcium aggregates were globular, connected with each other, and formed a shell covering cartilage matrix located within longitudinal septa.

3D printed dual macro-, microscale porous network as a tissue engineering scaffold with drug delivering function

Publisher: IOP Publishing

Date: 26-04-2019

DOI: 10.1088/1758-5090/AB14FF

Abstract: Tissue engineering macroporous scaffolds are important for regeneration of large volume defects resulting from diseases such as breast or bone cancers. Another important part of the treatment of these conditions is adjuvant drug therapy to prevent disease recurrence or surgical site infection. In this study, we developed a new type of macroporous scaffolds that have drug loading and release functionality to use in these scenarios. 3D printing allows for building macroporous scaffolds with deterministically designed complex architectures for tissue engineering yet they often have low surface areas thus limiting their drug loading capability. In this proof-of-concept study, we aimed to introduce microscale porosity into macroporous scaffolds to allow for efficient yet simple soak-loading of various clinical drugs and control their release. Manufacturing of scaffolds having both macroporosity and microscale porosity remains a difficult task. Here, we combined porogen leaching and 3D printing to achieve this goal. Porogen microparticles were mixed with medical grade polycaprolactone and extruded into scaffolds having macropores of 0.7 mm in size. After leaching, intra-strut microscale pores were realized with pore size of 20-70 μm and a total microscale porosity of nearly 40%. Doxorubicin (DOX), paclitaxel (PTX) and cefazolin (CEF) were chosen as model drugs of different charges and solubilities to soak-load the scaffolds and achieved loading efficiency of over 80%. The microscale porosity was found to significantly reduce the burst release allowing the microporous scaffolds to release drugs up to 200, 500 and 150 h for DOX, PTX and CEF, respectively. Finally, cell assays were used and confirmed the bioactivities and dose response of the drug-loaded scaffolds. Together, the findings from this proof-of-concept study demonstrate a new type of scaffolds with dual micro-, macro-porosity for tissue engineering applications with intrinsic capability for efficient loading and sustained release of drugs to prevent post-surgery complications.

Scaffold-cell bone engineering in a validated preclinical animal model: precursors vs differentiated cell source

Publisher: Hindawi Limited

Date: 09-12-2015

DOI: 10.1002/TERM.2104

Abstract: The properties of osteoblasts (OBs) isolated from the axial skeleton (tOBs) differ from OBs of the orofacial skeleton (mOBs) due to the different embryological origins of the bones. The aim of the study was to assess and compare the regenerative potential of allogenic bone marrow-derived mesenchymal progenitor cells with allogenic tOBs and allogenic mOBs in combination with a mPCL-TCP scaffold in critical-sized segmental bone defects in sheep tibiae. After 6 months, the tibiae were explanted and underwent biomechanical testing, micro-computed tomography (microCT) and histological and immunohistochemical analyses. Allogenic MPCs demonstrated a trend towards a better outcome in biomechanical testing and the mean values of newly formed bone. Biomechanical, microCT and histological analysis showed no significant differences in the bone regeneration potential of tOBs and mOBs in our in vitro study, as well as in the bone regeneration potential of different cell types in vivo. Copyright © 2015 John Wiley & Sons, Ltd.

Scaffold development using 3D printing with a starch-based polymer

Publisher: Elsevier BV

Date: 05-2002

DOI: 10.1016/S0928-4931(02)00012-7

Perspectives in Multiphasic Osteochondral Tissue Engineering

Publisher: Wiley

Date: 02-12-2013

DOI: 10.1002/AR.22795

Abstract: Critical-sized osteochondral defects are clinically challenging, with limited treatment options available. By engineering osteochondral grafts using a patient's own cells and osteochondral scaffolds designed to facilitate cartilage and bone regeneration, osteochondral defects may be treated with less complications and better long-term clinical outcomes. Scaffolds can influence the development and structure of the engineered tissue, and there is an increased awareness that osteochondral tissue engineering concepts need to take the in vivo complexities into account in order to increase the likelihood of successful osteochondral tissue repair. The developing trend in osteochondral tissue engineering is the utilization of multiphasic scaffolds to recapitulate the multiphasic nature of the native tissue. Cartilage and bone have different structural, mechanical, and biochemical microenvironments. By designing osteochondral scaffolds with tissue-specific architecture, it may be possible to enhance osteochondral repair within shorter timeframe. While there are promising in vivo outcomes using multiphasic approaches, functional regeneration of osteochondral constructs still remains a challenge. In this review, we provide an overview of in vivo osteochondral repair studies that have taken place in the past three years, and define areas which needs improvement in future studies.

How smart do biomaterials need to be? A translational science and clinical point of view

Publisher: Elsevier BV

Date: 04-2013

DOI: 10.1016/J.ADDR.2012.07.009

Abstract: Over the last 4 decades innovations in biomaterials and medical technology have had a sustainable impact on the development of biopolymers, titanium/stainless steel and ceramics utilized in medical devices and implants. This progress was primarily driven by issues of biocompatibility and demands for enhanced mechanical performance of permanent and non-permanent implants as well as medical devices and artificial organs. In the 21st century, the biomaterials community aims to develop advanced medical devices and implants, to establish techniques to meet these requirements, and to facilitate the treatment of older as well as younger patient cohorts. The major advances in the last 10 years from a cellular and molecular knowledge point of view provided the scientific foundation for the development of third-generation biomaterials. With the introduction of new concepts in molecular biology in the 2000s and specifically advances in genomics and proteomics, a differentiated understanding of biocompatibility slowly evolved. These cell biological discoveries significantly affected the way of biomaterials design and use. At the same time both clinical demands and patient expectations continued to grow. Therefore, the development of cutting-edge treatment strategies that alleviate or at least delay the need of implants could open up new vistas. This represents the main challenge for the biomaterials community in the 21st century. As a result, the present decade has seen the emergence of the fourth generation of biomaterials, the so-called smart or biomimetic materials. A key challenge in designing smart biomaterials is to capture the degree of complexity needed to mimic the extracellular matrix (ECM) of natural tissue. We are still a long way from recreating the molecular architecture of the ECM one to one and the dynamic mechanisms by which information is revealed in the ECM proteins in response to challenges within the host environment. This special issue on smart biomaterials lists a large number of excellent review articles which core is to present and discuss the basic sciences on the topic of smart biomaterials. On the other hand, the purpose of our review is to assess state of the art and future perspectives of the so called "smart biomaterials" from a translational science and specifically clinical point of view. Our aim is to filter out and discuss which biomedical advances and innovations help us to achieve the objective to translate smart biomaterials from bench to bedside. The authors predict that analyzing the field of smart biomaterials from a clinical point of view, looking back 50 years from now, it will show that this is our heritage in the 21st century.

Tissue Engineering of Articular Cartilage with Biomimetic Zones

Publisher: Mary Ann Liebert Inc

Date: 06-2009

DOI: 10.1089/TEN.TEB.2008.0563

Human and mouse bones physiologically integrate in a humanized mouse model while maintaining species-specific ultrastructure

Publisher: American Association for the Advancement of Science (AAAS)

Date: 30-10-2020

DOI: 10.1126/SCIADV.ABB9265

Abstract: Progress has been achieved in the art of accurately mimicking human tissues and disease in a mouse.

Immune system augmentation via humanization using stem/progenitor cells and bioengineering in a breast cancer model study

Publisher: Wiley

Date: 07-05-2018

DOI: 10.1002/IJC.31528

Abstract: Despite significant advances, most current in vivo models fail to fully recapitulate the biological processes that occur in humans. Here we aimed to develop an advanced humanized model with features of an organ bone by providing different bone tissue cellular compartments including preosteoblasts, mesenchymal stem/stromal (MSCs), endothelial and hematopoietic cells in an engineered microenvironment. The bone compartment was generated by culturing the human MSCs, umbilical vein endothelial cells with gelatin methacryloyl hydrogels in the center of a melt-electrospun polycaprolactone tubular scaffolds, which were seeded with human preosteoblasts. The tissue engineered bone (TEB) was subcutaneously implanted into the NSG mice and formed a morphologically and functionally organ bone. Mice were further humanized through the tail vein injection of human cord blood derived CD34+ cells, which then populated in the mouse bone marrow, spleen and humanized TEB (hTEB). 11 weeks after CD34+ transplantation, metastatic breast cancer cells (MDA-MB-231BO) were orthotopically injected. Cancer cell injection resulted in the formation of a primary tumor and metastasis to the hTEB and mouse organs. Less frequent metastasis and lower tumor burden were observed in hematochimeric mice, suggesting an immune-mediated response against the breast cancer cells. Overall, our results demonstrate the efficacy of tissue engineering approaches to study species-specific cancer-bone interactions. Further studies using genetically modified hematopoietic stem cells and bioengineered microenvironments will enable us to address the specific roles of signaling molecules regulating hematopoietic niches and cancer metastasis in vivo.

Enhancement of bone ingrowth into a porous hydroxylapatite-matrix using a resorbable polylactic membrane: An experimental pilot study

Publisher: Elsevier BV

Date: 1994

DOI: 10.1016/0278-2391(94)90016-7

Abstract: The objective of this pilot study was to study bone ingrowth into porous hydroxylapatite (HA) blocks using a polylactic membrane for guided tissue regeneration. Porous HA blocks were placed on both sides of the mandible and of the ilium in five Göttingen minipigs. On one side a polylactic membrane was used to cover the blocks. After 5 months, the blocks with the membrane covering showed complete bony penetration of the HA matrix both in the mandible and the ilium. The blocks without the membrane covering showed substantially less and irregular bone ingrowth after placement on the mandible and poor ingrowth after placement on the ilium. The newly formed bone in the blocks from the ilium showed a cancellous structure while bone tissue inside the blocks from the mandible exhibited a dense cortical appearance. The polylactic membrane was nearly completely degraded at the time of investigation.

Microparticles for Sustained Growth Factor Delivery in the Regeneration of Critically-Sized Segmental Tibial Bone Defects

Publisher: MDPI AG

Date: 31-03-2016

DOI: 10.3390/MA9040259

The stimulation of healing within a rat calvarial defect by mPCL-TCP/collagen scaffolds loaded with rhBMP-2

Publisher: Elsevier BV

Date: 05-2009

DOI: 10.1016/J.BIOMATERIALS.2008.12.055

Abstract: Bone morphogenetic proteins (BMPs) have been widely investigated for their clinical use in bone repair and it is known that a suitable carrier matrix to deliver them is essential for optimal bone regeneration within a specific defect site. Fused deposited modeling (FDM) allows for the fabrication of medical grade poly epsilon-caprolactone/tricalcium phosphate (mPCL-TCP) scaffolds with high reproducibility and tailor designed dimensions. Here we loaded FDM fabricated mPCL-TCP/collagen scaffolds with 5 microg recombinant human (rh)BMP-2 and evaluated bone healing within a rat calvarial critical-sized defect. Using a comprehensive approach, this study assessed the newly regenerated bone employing micro-computed tomography (microCT), histology/histomorphometry, and mechanical assessments. By 15 weeks, mPCL-TCP/collagen/rhBMP-2 defects exhibited complete healing of the calvarium whereas the non-BMP-2-loaded scaffolds showed significant less bone ingrowth, as confirmed by microCT. Histomorphometry revealed significantly increased bone healing amongst the rhBMP-2 groups compared to non-treated scaffolds at 4 and 15 weeks, although the % BV/TV did not indicate complete mineralisation of the entire defect site. Hence, our study confirms that it is important to combine microCt and histomorphometry to be able to study bone regeneration comprehensively in 3D. A significant up-regulation of the osteogenic proteins, type I collagen and osteocalcin, was evident at both time points in rhBMP-2 groups. Although mineral apposition rates at 15 weeks were statistically equivalent amongst treatment groups, micro-compression and push-out strengths indicated superior bone quality at 15 weeks for defects treated with mPCL-TCP/collagen/rhBMP-2. Consistently over all modalities, the progression of healing was from empty defect<mPCL-TCP/collagen<mPCL-TCP/collagen/rhBMP-2, providing substantiating data to support the hypothesis that the release of rhBMP-2 from FDM-created mPCL-TCP/collagen scaffolds is a clinically relevant approach to repair and regenerate critically-sized craniofacial bone defects.

Tie-2 regulates the stemness and metastatic properties of prostate cancer cells

Publisher: Impact Journals, LLC

Date: 29-04-2016

DOI: 10.18632/ONCOTARGET.3950

Melt electrospinning onto cylinders: effects of rotational velocity and collector diameter on morphology of tubular structures

Publisher: Wiley

Date: 15-06-2015

DOI: 10.1002/PI.4948

Autocrine fibroblast growth factor 2 increases the multipotentiality of human adipose-derived mesenchymal stem cells

Publisher: Oxford University Press (OUP)

Date: 20-03-2008

DOI: 10.1634/STEMCELLS.2007-0480

Abstract: Multipotent mesenchymal stem cells (MSCs), first identified in the bone marrow, have subsequently been found in many other tissues, including fat, cartilage, muscle, and bone. Adipose tissue has been identified as an alternative to bone marrow as a source for the isolation of MSCs, as it is neither limited in volume nor as invasive in the harvesting. This study compares the multipotentiality of bone marrow-derived mesenchymal stem cells (BMSCs) with that of adipose-derived mesenchymal stem cells (AMSCs) from 12 age- and sex-matched donors. Phenotypically, the cells are very similar, with only three surface markers, CD106, CD146, and HLA-ABC, differentially expressed in the BMSCs. Although colony-forming units-fibroblastic numbers in BMSCs were higher than in AMSCs, the expression of multiple stem cell-related genes, like that of fibroblast growth factor 2 (FGF2), the Wnt pathway effectors FRAT1 and frizzled 1, and other self-renewal markers, was greater in AMSCs. Furthermore, AMSCs displayed enhanced osteogenic and adipogenic potential, whereas BMSCs formed chondrocytes more readily than AMSCs. However, by removing the effects of proliferation from the experiment, AMSCs no longer out-performed BMSCs in their ability to undergo osteogenic and adipogenic differentiation. Inhibition of the FGF2/fibroblast growth factor receptor 1 signaling pathway demonstrated that FGF2 is required for the proliferation of both AMSCs and BMSCs, yet blocking FGF2 signaling had no direct effect on osteogenic differentiation. Disclosure of potential conflicts of interest is found at the end of this article.

Bone Tissue Engineering

Publisher: Springer Berlin Heidelberg

Date: 24-11-2010

DOI: 10.1007/978-3-642-02824-3_21

Humanized mice models for primary bone tumor and bone metastasis research

Publisher: Informa UK Limited

Date: 15-07-2015

DOI: 10.1080/15384101.2015.1062327

3‐Dimensional functionalized polycaprolactone‐hyaluronic acid hydrogel constructs for bone tissue engineering

Publisher: Wiley

Date: 18-02-2017

DOI: 10.1111/JCPE.12686

Abstract: Alveolar bone regeneration remains a significant clinical challenge in periodontology and dental implantology. This study assessed the mineralized tissue forming potential of 3-D printed medical grade polycaprolactone (mPCL) constructs containing osteoblasts (OB) encapsulated in a hyaluronic acid (HA)-hydrogel incorporating bone morphogenetic protein-7 (BMP-7). HA-hydrogels containing human OB ± BMP-7 were prepared. Cell viability, osteogenic gene expression, mineralized tissue formation and BMP-7 release in vitro, were assessed by fluorescence staining, RT-PCR, histological/μ-CT examination and ELISA respectively. In an athymic rat model, subcutaneous ectopic mineralized tissue formation in mPCL-hydrogel constructs was assessed by μ-CT and histology. Osteoblast encapsulation in HA-hydrogels did not detrimentally effect cell viability, and 3-D culture in osteogenic media showed mineralized collagenous matrix formation after 6 weeks. BMP-7 release from the hydrogel was biphasic, sustained and increased osteogenic gene expression in vitro. After 4 weeks in vivo, mPCL-hydrogel constructs containing BMP-7 formed significantly more volume (mm Functionalized mPCL-HA hydrogel constructs provide a favourable environment for bone tissue engineering. Although encapsulated cells contributed to mineralized tissue formation within the hydrogel in vitro and in vivo, their addition did not result in an improved outcome compared to BMP-7 alone.

Absolute quantification of gene expression in biomaterials research using real-time PCR

Publisher: Elsevier BV

Date: 2007

DOI: 10.1016/J.BIOMATERIALS.2006.09.011

Abstract: One major measurement of tissue-engineered constructs efficacy and performance is determining expression levels of genes of interest at the molecular level. This measurement is commonly carried out with reverse transcription-polymerase chain reaction (RT-PCR). In this study, we described a novel method in achieving absolute quantification of gene expression using real-time PCR (aqPCR). This novel method did not require molecular cloning steps to prepare the standards for quantification comparison. Standards were linear double-stranded DNA molecules instead of the typical gene-in-plasmid format. aqPCR could also be used to give relative quantification comparisons between s les simply by iding the copy numbers readings of the gene of interest with that of the normalization gene. RNA was extracted from monolayer and from polycaprolactone scaffold cultures and assayed for beta-actin and osteocalcin genes. We compared our aqPCR method with end-point PCR since end-point PCR is still a common means of measuring gene expression in the biomaterials field. This study showed that aqPCR was a better method to quantify gene expression than end-point PCR. With our described linear DNA standards method, we were able to obtain not only relative quantification of osteocalcin and beta-actin expression level but also actual copy numbers of osteocalcin and beta-actin for the monolayer culture and to be 1.34 x 10(4) and 1.45 x 10(7) copies, respectively and for the scaffold cultures to be 772 and 2.83 x 10(5) copies, respectively per starting total RNA mass of 10 ng. The standards curves made from these linear DNA standards showed good linearity (R(2)=0.9964 and 0.9902 for osteocalcin and beta-actin standards graphs), ranged from 10 to 10(9) copies and of comparable accuracy to current absolute quantification real-time PCR methods (which used plasmid standards obtained through molecular cloning methods). Our method might be a viable and more user-friendly alternative to current absolute quantification real-time PCR protocols.

Polylactides in additive biomanufacturing

Publisher: Elsevier BV

Date: 12-2006

DOI: 10.1016/J.ADDR.2016.07.006

Abstract: New advanced manufacturing technologies under the alias of additive biomanufacturing allow the design and fabrication of a range of products from pre-operative models, cutting guides and medical devices to scaffolds. The process of printing in 3 dimensions of cells, extracellular matrix (ECM) and biomaterials (bioinks, powders, etc.) to generate in vitro and/or in vivo tissue analogue structures has been termed bioprinting. To further advance in additive biomanufacturing, there are many aspects that we can learn from the wider additive manufacturing (AM) industry, which have progressed tremendously since its introduction into the manufacturing sector. First, this review gives an overview of additive manufacturing and both industry and academia efforts in addressing specific challenges in the AM technologies to drive toward AM-enabled industrial revolution. After which, considerations of poly(lactides) as a biomaterial in additive biomanufacturing are discussed. Challenges in wider additive biomanufacturing field are discussed in terms of (a) biomaterials (b) computer-aided design, engineering and manufacturing (c) AM and additive biomanufacturing printers hardware and (d) system integration. Finally, the outlook for additive biomanufacturing was discussed.

Silk fibroin in ocular tissue reconstruction

Publisher: Elsevier BV

Date: 04-2011

DOI: 10.1016/J.BIOMATERIALS.2010.12.041

Abstract: The silk structural protein fibroin displays potential for use in tissue engineering. We present here our opinion of its value as a biomaterial for reconstructing tissues of clinical significance within the human eye. We review the strengths and weaknesses of using fibroin in those parts of the eye that we believe are most amenable to cellular reconstruction, namely the corneoscleral limbus, corneal stroma, corneal endothelium and outer blood-retinal barrier (Ruysch's complex). In these areas we find that by employing the range of manufacturing products afforded by fibroin, relevant structural assemblies can be made for cells expanded ex vivo. Significant questions now need to be answered concerning the effect of this biomaterial on the phenotype of key cell types and the biocompatibility of fibroin within the eye. We conclude that fibroin's strength, structural versatility and potential for modification, combined with the relative simplicity of associated manufacturing processes, make fibroin a worthy candidate for further exploration.

Experimental transplantation of hydroxylapatite-bone composite grafts

Publisher: Elsevier BV

Date: 1995

DOI: 10.1016/0278-2391(95)90500-6

Abstract: This study was undertaken to determine if autogenous bone can be cultivated in vivo in a porous hydroxylapatite (HA) matrix by ingrowth from underlying bone and if this autogenous HA-bone composite graft can then be transplanted. Five Göttingen minipigs received subperiosteal implantation of one HA block each (40 x 10 x 10 mm), covered by a polylactic membrane, on the ascending ramus of the mandible. After 5 months, half of each implant was harvested and transplanted as an onlay graft to the horizontal ramus of the mandible with simultaneous insertion of a titanium implant. Polychrome fluorescence labeling was done 1, 2, 4, and 8 weeks postoperatively. After 3 months, the vascular system of the animals was filled with BaSO4 for microangiographic examination, and all blocks were retrieved. Fluorescence microscopy showed that there was a significant decrease in deposition of the label in the grafted blocks at 1 week when compared with later labels. After the second week, there were no significant changes. A 20% to 30% decrease in the frequency of fluorochrome staining was noted in the upper third of each block. In this region, microangiography demonstrated highly vascularized tissue and limited bone resorption. It was concluded that cultivation of mandibular bone in a porous matrix under guided bone regeneration is possible and that this autogenous HA-bone composite graft can be transplanted at a later date.

Effect of culture conditions and calcium phosphate coating on ectopic bone formation

Publisher: Elsevier BV

Date: 07-2013

DOI: 10.1016/J.BIOMATERIALS.2013.03.088

Abstract: This study investigated the effect of a calcium phosphate (CaP) coating onto a polycaprolactone melt electrospun scaffold and in vitro culture conditions on ectopic bone formation in a subcutaneous rat model. The CaP coating resulted in an increased alkaline phosphatase activity (ALP) in ovine osteoblasts regardless of the culture conditions and this was also translated into higher levels of mineralisation. A subcutaneous implantation was performed and increasing ectopic bone formation was observed over time for the CaP-coated s les previously cultured in osteogenic media whereas the corresponding non-coated s les displayed a lag phase before bone formation occurred from 4 to 8 weeks post-implantation. Histology and immunohistochemistry revealed bone fill through the scaffolds 8 weeks post-implantation for coated and non-coated specimens and that ALP, osteocalcin and collagen 1 were present at the ossification front and in the bone tissues. Vascularisation in the vicinity of the bone tissues was also observed indicating that the newly formed bone was not deprived of oxygen and nutrients. We found that in vitro osteogenic induction was essential for achieving bone formation and CaP coating accelerated the osteogenic process. We conclude that high cell density and preservation of the collagenous and mineralised extracellular matrix secreted in vitro are factors of importance for ectopic bone formation.

Elastic cartilage engineering using novel scaffold architectures in combination with a biomimetic cell carrier

Publisher: Elsevier BV

Date: 11-2003

DOI: 10.1016/S0142-9612(03)00350-8

Abstract: Tissue engineering of an elastic cartilage graft that meets the criterion for both structural and functional integration into host tissue, as well as allowing for a clinically tolerable immune response, is a challenging endeavour. Conventional scaffold technologies have limitations in their ability to design and fabricate complex-shaped matrix architectures of structural and mechanical equivalence to elastic cartilage found in the body. We attempted to investigate the potential of conventionally isolated and passaged chondrocytes (2D environment) when seeded and cultured in combination with a biomimetic hydrogel in a mechanically stable and biomimetic composite matrix to form elastic cartilage within ectopic implantation sites. In vitro cultured scaffold/hydrogel/chondrocytes constructs showed islets of cartilage and mineralized tissue formation within the cell-seeded specimens in both pig and rabbit models. Specimens with no cells seeded showed only vascularized fibrous tissue ingrowth. These studies demonstrated the potential of such scaffold/hydrogel/cell constructs to support chondrogenesis in vivo. However, it also showed that even mechanically stable scaffolds do not allow regeneration of a large mass of structural and functional cartilage within a matrix architecture seeded with 2D passaged chondrocytes in combination with a cell biomimetic carrier. Hence, future experiments will be designed to evaluate an initial 3D culture of chondrocytes, effect on cell phenotype and their subsequent culture within biomimetic 3D scaffold/cell constructs.

The development of a modular design workflow for 3D printable bioresorbable patient-specific bone scaffolds to facilitate clinical translation

Publisher: Informa UK Limited

Date: 05-09-2023

DOI: 10.1080/17452759.2023.2246434

A comparative analysis of scaffold material modifications for load-bearing applications in bone tissue engineering

Publisher: Elsevier BV

Date: 10-2006

DOI: 10.1016/J.IJOM.2006.03.024

Abstract: To facilitate optimal application of appropriate scaffold architectures for clinical trials, there is a need to compare different scaffold modifications under similar experimental conditions. In this study was assessed the effectiveness of poly-e-caprolactone (PCL) scaffolds fabricated by fused deposition modelling (FDM), with varying material modifications, for the purposes of bone tissue engineering. The incorporation of hydroxyapatite (HA) in PCL scaffolds, as well as precalcification through immersion in a simulated body fluid (SBF) to produce a biomimetic apatite coating on the scaffolds, was assessed. A series of in vitro studies spanning 3 weeks as well as in vivo studies utilizing a subcutaneous nude mouse model were carried out. PCL and HA-PCL scaffolds demonstrated increasing tissue growth extending throughout the implants, as well as superior mechanical strength and mineralization, as evidenced by X-ray imaging after 14 weeks in vivo. No significant difference was found between PCL and HA-PCL scaffolds. Precalcification with SBF did not result in increased osteoconductivity and cell proliferation as previously reported. Conversely, tensile forces exerted by tissue sheets bridging adjacent struts of the PCL scaffold caused flaking of the apatite coating that resulted in impaired cell attachment, growth and mineralization. The results suggest that scaffolds fabricated by FDM may have load-bearing applications.

Melt Electrospinning and Its Technologization in Tissue Engineering

Publisher: Mary Ann Liebert Inc

Date: 04-2015

DOI: 10.1089/TEN.TEB.2014.0347

Bone Tissue Engineering: Cell Motility, Vascularization, Micro-Nano Scaffolding, and Remodeling

Publisher: Hindawi Limited

Date: 2014

DOI: 10.1155/2014/286978

Periosteum tissue engineering in an orthotopic in vivo platform

Publisher: Elsevier BV

Date: 03-2017

DOI: 10.1016/J.BIOMATERIALS.2016.11.016

Abstract: The periosteum plays a critical role in bone homeostasis and regeneration. It contains a vascular component that provides vital blood supply to the cortical bone and an osteogenic niche that acts as a source of bone-forming cells. Periosteal grafts have shown promise in the regeneration of critical size defects, however their limited availability restricts their widespread clinical application. Only a small number of tissue-engineered periosteum constructs (TEPCs) have been reported in the literature. A current challenge in the development of appropriate TEPCs is a lack of pre-clinical models in which they can reliably be evaluated. In this study, we present a novel periosteum tissue engineering concept utilizing a multiphasic scaffold design in combination with different human cell types for periosteal regeneration in an orthotopic in vivo platform. Human endothelial and bone marrow mesenchymal stem cells (BM-MSCs) were used to mirror both the vascular and osteogenic niche respectively. Immunohistochemistry showed that the BM-MSCs maintained their undifferentiated phenotype. The human endothelial cells developed into mature vessels and connected to host vasculature. The addition of an in vitro engineered endothelial network increased vascularization in comparison to cell-free constructs. Altogether, the results showed that the human TEPC (hTEPC) successfully recapitulated the osteogenic and vascular niche of native periosteum, and that the presented orthotopic xenograft model provides a suitable in vivo environment for evaluating scaffold-based tissue engineering concepts exploiting human cells.

Effect of Collagen-I Modified Composites on Proliferation and Differentiation of Human Alveolar Osteoblasts

Publisher: CSIRO Publishing

Date: 2006

DOI: 10.1071/CH06165

Abstract: Collagen modification of scaffolds has been reported to promote matrix mineralization as an effective way to increase osseointegration of implants. The aim of this study was to investigate in vitro proliferation and differentiation of human alveolar osteoblasts (AOs) on medical-grade polycaprolactone–tricalcium phosphate (mPCL-TCP 80:20) scaffolds after collagen modification (mPCL-TCP-c) for 28 days. Collagen modification significantly increased the scaffold’s protein adsorption ability, and improved the initial seeding efficiency and cell attachment at day 1, compared with non-collagen-modified scaffolds. However, the total DNA content of both groups reached similar levels with no significant difference at 28 days’ culture. AOs were observed to spread along the collagen fibres and form extensive collagenous fibres with mineral nodules embedded, while multilayered cell sheets were formed in mPCL-TCP scaffolds. During culture, alkaline phosphatase (ALP) activity increased three- to five-fold in both groups, and collagen modification did not significantly affect either the metabolic rate or ALP activity kinetics of AOs. During osteogenic differentiation, similar gene expression of collagen type-I, osterix, osteopontin, and osteocalcin were detected in both groups. The mPCL-TCP group showed better organized mineralized tissue, but the mPCL-TCP-c showed more scattered and unorganized tissue. These results indicate that collagen modification improved the scaffold’s protein adsorption ability and encouraged initial cell attachment and distribution, but promoted fibrous-like tissue formation rather than mineralized tissue.

Comparative study of depth-dependent characteristics of equine and human osteochondral tissue from the medial and lateral femoral condyles

Publisher: Elsevier BV

Date: 10-2012

DOI: 10.1016/J.JOCA.2012.06.005

Abstract: Articular cartilage defects are common after joint injuries. When left untreated, the biomechanical protective function of cartilage is gradually lost, making the joint more susceptible to further damage, causing progressive loss of joint function and eventually osteoarthritis (OA). In the process of translating promising tissue-engineering cartilage repair approaches from bench to bedside, pre-clinical animal models including mice, rabbits, goats, and horses, are widely used. The equine species is becoming an increasingly popular model for the in vivo evaluation of regenerative orthopaedic approaches. As there is also an increasing body of evidence suggesting that successful lasting tissue reconstruction requires an implant that mimics natural tissue organization, it is imperative that depth-dependent characteristics of equine osteochondral tissue are known, to assess to what extent they resemble those in humans. Therefore, osteochondral cores (4-8 mm) were obtained from the medial and lateral femoral condyles of equine and human donors. Cores were processed for histology and for biochemical quantification of DNA, glycosaminoglycan (GAG) and collagen content. Equine and human osteochondral tissues possess similar geometrical (thickness) and organizational (GAG, collagen and DNA distribution with depth) features. These comparable trends further underscore the validity of the equine model for the evaluation of regenerative approaches for articular cartilage.

Delayed Minimally Invasive Injection of Allogenic Bone Marrow Stromal Cell Sheets Regenerates Large Bone Defects in an Ovine Preclinical Animal Model

Publisher: Oxford University Press (OUP)

Date: 04-2015

DOI: 10.5966/SCTM.2014-0244

Abstract: From a translational point of view, a comprehensive study is presented, the results of which show that percutaneous injection of allogenic BMSCs into the biodegradable composite scaffold 4 weeks after the defect surgery led to significantly improved bone regeneration compared with preseeded scaffold/cell constructs and scaffold-only groups. Biomechanical testing and microcomputed tomography showed results comparable to those of the clinical gold standard, namely autologous autograft. To the authors' knowledge, this is the first study to display in a validated preclinical large animal model that delayed allogenic cell transplantation could provide clinical treatment alternatives for challenging bone defects in the future.

Biological performance of a polycaprolactone-based scaffold used as fusion cage device in a large animal model of spinal reconstructive surgery

Publisher: Elsevier BV

Date: 10-2009

DOI: 10.1016/J.BIOMATERIALS.2009.05.067

Abstract: A bioactive and bioresorbable scaffold fabricated from medical grade poly (epsilon-caprolactone) and incorporating 20% beta-tricalcium phosphate (mPCL-TCP) was recently developed for bone regeneration at load bearing sites. In the present study, we aimed to evaluate bone ingrowth into mPCL-TCP in a large animal model of lumbar interbody fusion. Six pigs underwent a 2-level (L3/4 L5/6) anterior lumbar interbody fusion (ALIF) implanted with mPCL-TCP + 0.6 mg rhBMP-2 as treatment group while four other pigs implanted with autogenous bone graft served as control. Computed tomographic scanning and histology revealed complete defect bridging in all (100%) specimen from the treatment group as early as 3 months. Histological evidence of continuing bone remodeling and maturation was observed at 6 months. In the control group, only partial bridging was observed at 3 months and only 50% of segments in this group showed complete defect bridging at 6 months. Furthermore, 25% of segments in the control group showed evidence of graft fracture, resorption and pseudoarthrosis. In contrast, no evidence of graft fractures, pseudoarthrosis or foreign body reaction was observed in the treatment group. These results reveal that mPCL-TCP scaffolds could act as bone graft substitutes by providing a suitable environment for bone regeneration in a dynamic load bearing setting such as in a porcine model of interbody spine fusion.

Advanced tissue engineering scaffold design for regeneration of the complex hierarchical periodontal structure

Publisher: Wiley

Date: 05-02-2014

DOI: 10.1111/JCPE.12214

Abstract: This study investigated the ability of an osteoconductive biphasic scaffold to simultaneously regenerate alveolar bone, periodontal ligament and cementum. A biphasic scaffold was built by attaching a fused deposition modelled bone compartment to a melt electrospun periodontal compartment. The bone compartment was coated with a calcium phosphate (CaP) layer for increasing osteoconductivity, seeded with osteoblasts and cultured in vitro for 6 weeks. The resulting constructs were then complemented with the placement of PDL cell sheets on the periodontal compartment, attached to a dentin block and subcutaneously implanted into athymic rats for 8 weeks. Scanning electron microscopy, X-ray diffraction, alkaline phosphatase and DNA content quantification, confocal laser microscopy, micro computerized tomography and histological analysis were employed to evaluate the scaffold's performance. The in vitro study showed that alkaline phosphatase activity was significantly increased in the CaP-coated s les and they also displayed enhanced mineralization. In the in vivo study, significantly more bone formation was observed in the coated scaffolds. Histological analysis revealed that the large pore size of the periodontal compartment permitted vascularization of the cell sheets, and periodontal attachment was achieved at the dentin interface. This work demonstrates that the combination of cell sheet technology together with an osteoconductive biphasic scaffold could be utilized to address the limitations of current periodontal regeneration techniques.

Degradation characteristics of poly(ϵ‐caprolactone)‐based copolymers and blends

Publisher: Wiley

Date: 28-07-2006

DOI: 10.1002/APP.24196

Abstracts from the Spectra 2018 Symposium: Environment and Bio-Science

Publisher: MIT Press

Date: 16-09-2020

DOI: 10.1162/LEON_A_01974

Assessment of bone ingrowth into porous biomaterials using MICRO-CT

Publisher: Elsevier BV

Date: 05-2007

DOI: 10.1016/J.BIOMATERIALS.2007.01.046

Abstract: The three-dimensional (3D) structure and architecture of biomaterial scaffolds play a critical role in bone formation as they affect the functionality of the tissue-engineered constructs. Assessment techniques for scaffold design and their efficacy in bone ingrowth studies require an ability to accurately quantify the 3D structure of the scaffold and an ability to visualize the bone regenerative processes within the scaffold structure. In this paper, a 3D micro-CT imaging and analysis study of bone ingrowth into tissue-engineered scaffold materials is described. Seven specimens are studied in this paper a set of three specimens with a cellular structure, varying pore size and implant material, and a set of four scaffolds with two different scaffold designs investigated at early (4 weeks) and late (12 weeks) explantation times. The difficulty in accurately phase separating the multiple phases within a scaffold undergoing bone regeneration is first highlighted. A sophisticated three-phase segmentation approach is implemented to develop high-quality phase separation with minimal artifacts. A number of structural characteristics and bone ingrowth characteristics of the scaffolds are quantitatively measured on the phase separated images. Porosity, pore size distributions, pore constriction sizes, and pore topology are measured on the original pore phase of the scaffold volumes. The distribution of bone ingrowth into the scaffold pore volume is also measured. For early explanted specimens we observe that bone ingrowth occurs primarily at the periphery of the scaffold with a constant decrease in bone mineralization into the scaffold volume. Pore size distributions defined by both the local pore geometry and by the largest accessible pore show distinctly different behavior. The accessible pore size is strongly correlated to bone ingrowth. In the specimens studied a strong enhancement of bone ingrowth is observed for pore diameters>100 microm. Little difference in bone ingrowth is measured with different scaffold design. This result illustrates the benefits of microtomography for analyzing the 3D structure of scaffolds and the resultant bone ingrowth.

Erratum: Phenotypic characterization of prostate cancer LNCaP Cells cultured within a bioengineered microenvironment (PLoS ONE (2013) 8:1 DOI: 10.1371/annotation/a26f1a2e-2765-4c10-942e-d2a738b80bf9)

Publisher: Public Library of Science (PLoS)

Date: 17-01-2013

DOI: 10.1371/ANNOTATION/A26F1A2E-2765-4C10-942E-D2A738B80BF9

Humanised xenograft models of bone metastasis revisited: Novel insights into species-specific mechanisms of cancer cell osteotropism

Publisher: Springer Science and Business Media LLC

Date: 09-05-2013

DOI: 10.1007/S10555-013-9437-5

Abstract: The determinants and key mechanisms of cancer cell osteotropism have not been identified, mainly due to the lack of reproducible animal models representing the biological, genetic and clinical features seen in humans. An ideal model should be capable of recapitulating as many steps of the metastatic cascade as possible, thus facilitating the development of prognostic markers and novel therapeutic strategies. Most animal models of bone metastasis still have to be derived experimentally as most syngeneic and transgeneic approaches do not provide a robust skeletal phenotype and do not recapitulate the biological processes seen in humans. The xenotransplantation of human cancer cells or tumour tissue into immunocompromised murine hosts provides the possibility to simulate early and late stages of the human disease. Human bone or tissue-engineered human bone constructs can be implanted into the animal to recapitulate more subtle, species-specific aspects of the mutual interaction between human cancer cells and the human bone microenvironment. Moreover, the replication of the entire "organ" bone makes it possible to analyse the interaction between cancer cells and the haematopoietic niche and to confer at least a partial human immunity to the murine host. This process of humanisation is facilitated by novel immunocompromised mouse strains that allow a high engraftment rate of human cells or tissue. These humanised xenograft models provide an important research tool to study human biological processes of bone metastasis.

CAD/CAM-assisted breast reconstruction

Publisher: IOP Publishing

Date: 09-2011

DOI: 10.1088/1758-5082/3/3/034114

Abstract: The application of computer-aided design and manufacturing (CAD/CAM) techniques in the clinic is growing slowly but steadily. The ability to build patient-specific models based on medical imaging data offers major potential. In this work we report on the feasibility of employing laser scanning with CAD/CAM techniques to aid in breast reconstruction. A patient was imaged with laser scanning, an economical and facile method for creating an accurate digital representation of the breasts and surrounding tissues. The obtained model was used to fabricate a customized mould that was employed as an intra-operative aid for the surgeon performing autologous tissue reconstruction of the breast removed due to cancer. Furthermore, a solid breast model was derived from the imaged data and digitally processed for the fabrication of customized scaffolds for breast tissue engineering. To this end, a novel generic algorithm for creating porosity within a solid model was developed, using a finite element model as intermediate.

Tuning mechanical reinforcement and bioactivity of 3D printed ternary nanocomposites by interfacial peptide-polymer conjugates

Publisher: IOP Publishing

Date: 12-06-2019

DOI: 10.1088/1758-5090/AAFEC8

Abstract: We present a study on ternary nanocomposites consisting of medical grade poly(ε-caprolactone) (mPCL) matrix, hydroxyapatite nanopowder (nHA) and compatibilized magnesium fluoride nanoparticle (cMgF

Mineralization of plasma treated polymer surfaces from super-saturated simulated body fluids

Publisher: Elsevier BV

Date: 11-2018

DOI: 10.1016/J.MATLET.2018.07.078

The effect of unlocking RGD-motifs in collagen I on pre-osteoblast adhesion and differentiation

Publisher: Elsevier BV

Date: 04-2010

DOI: 10.1016/J.BIOMATERIALS.2009.12.051

Abstract: Denaturation of extracellular matrix proteins exposes cryptic binding sites. It is hypothesized that binding of cell adhesion receptors to these cryptic binding sites regulates cellular behaviour during tissue repair and regeneration. To test this hypothesis, we quantify the adhesion of pre-osteoblastic cells to native (Col) and partially-denatured (pdCol) collagen I using single-cell force spectroscopy. During early stages of cell attachment (< or =180 s) pre-osteoblasts (MC3T3-E1) adhered significantly stronger to pdCol compared to Col. RGD (Arg-Gly-Asp)-containing peptides suppressed this elevated cell adhesion. We show that the RGD-binding alpha(5)beta(1)- and alpha(v)-integrins mediated pre-osteoblast adhesion to pdCol, but not to Col. On pdCol pre-osteoblasts had a higher focal adhesion kinase tyrosine-phosphorylation level that correlated with enhanced spreading and motility. Moreover, pre-osteoblasts cultured on pdCol showed a pronounced matrix mineralization activity. Our data suggest that partially-denatured collagen exposes RGD-motifs that trigger binding of alpha(5)beta(1)- and alpha(v)-integrins. These integrins initiate cellular processes that stimulate osteoblast adhesion, spreading, motility and differentiation. Taken together, these quantitative insights reveal an approach for the development of alternative collagen I- based surfaces for tissue engineering applications.

A consumer designed smartphone app for young people with asthma: pilot of engagement and acceptability

Publisher: Informa UK Limited

Date: 06-11-2019

DOI: 10.1080/02770903.2019.1680997

Combined expression of KLK4, KLK5, KLK6, and KLK7 by ovarian cancer cells leads to decreased adhesion and paclitaxel-induced chemoresistance

Publisher: Elsevier BV

Date: 12-2012

DOI: 10.1016/J.YGYNO.2012.09.001

Abstract: Chemoresistance is a critical feature of advanced ovarian cancer with only 30% of patients surviving longer than 5 years. We have previously shown that four kallikrein-related (KLK) peptidases, KLK4, KLK5, KLK6 and KLK7 (KLK4-7), are implicated in peritoneal invasion and tumour growth, but underlying mechanisms were not identified. We also reported that KLK7 overexpression confers chemoresistance to paclitaxel, and cell survival via integrins. In this study, we further explored the functional consequenses of overexpression of all four KLKs (KLK4-7) simultaneously in the ovarian cancer cell line, OV-MZ-6, and its impact on integrin expression and signalling, cell adhesion and survival as contributors to chemoresistance and metastatic progression. Quantitative gene and protein expression analyses, confocal microscopy, cell adhesion and chemosensitivity assays were performed. Expression of α5β1/αvβ3 integrins was downregulated upon combined stable KLK4-7 overexpression in OV-MZ-6 cells. Accordingly, the adhesion of these cells to vitronectin and fibronectin, the extracellular matrix binding proteins of α5β1/αvβ3 integrins and two predominant proteins of the peritoneal matrix, was decreased. KLK4-7-transfected cells were more resistant to paclitaxel (10-100 nmol/L: 38-54%), but not to carboplatin, which was associated with decreased apoptotic stimuli. However, the KLK4-7-induced paclitaxel resistance was not blocked by the MEK1/2 inhibitor, U0126. This study demonstrates that combined KLK4-7 expression by ovarian cancer cells promotes reduced integrin expression with consequently less cell-matrix attachment, and insensitivity to paclitaxel mediated by complex integrin and MAPK independent interactions, indicative of a malignant phenotype and disease progression suggesting a role for these KLKs in this process.

Radium 223-Mediated zonal cytotoxicity of prostate cancer in Bone

Publisher: Oxford University Press (OUP)

Date: 18-01-2019

DOI: 10.1093/JNCI/DJZ007

Abstract: Bone-targeting radiotherapy with Radium-223 (Rad-223), a radioisotope emitting genotoxic alpha-radiation with limited tissue penetrance (∼100 µm), prolongs the survival of patients with metastatic prostate cancer (PCa). Confoundingly, the clinical response to Rad-223 is often followed by detrimental relapse and progression, and whether Rad-223 causes tumor-cell directed cytotoxicity in vivo remains unclear. We hypothesized that limited radiation penetrance in situ defines outcome. We tested Rad-223 overall response by PC3 and C4–2B human PCa cell lines in mouse bones (n = 5–18 tibiae per group). Rad-223 efficacy at subcellular resolution was determined by intravital microscopy analysis of dual-color fluorescent PC3 cells (n = 3–4 mice per group) in tissue-engineered bone constructs. In vivo data were fed into an in silico model to predict Rad-223 effectiveness in lesions of different sizes (1–27, 306 initial cells n = 10–100 simulations) and the predictions validated in vivo by treating PCa tumors of varying sizes in bones (n = 10–14 tibiae per group). Statistical tests were performed by two-sided Student t test or by one-way ANOVA followed by Tukey’s post-hoc test. Rad-223 (385 kBq/kg) delayed the growth (means [SD] comparison with control-treated mice) of PC3 (6.7 × 105[4.2 × 105] vs 2.8 × 106 [2.2 × 106], P = .01) and C4–2B tumors in bone (7.7 × 105 [4.0 × 105] vs 3.5 × 106 [1.3 × 106], P .001). Cancer cell lethality in response to Rad-223 (385 kBq/kg) was profound but zonally confined along the bone interface compared with the more distant tumor core, which remained unperturbed (day 4 13.1 [2.3%] apoptotic cells, 0–100 µm distance from bone vs 3.6 [0.2%], µm distance P = .01).In silico simulations predicted greater efficacy of Rad-223 on single-cell lesions (eradication rate: 88.0%) and minimal effects on larger tumors (no eradication, 16.2% growth reduction in tumors of 27 306 cells), as further confirmed in vivo for PC3 and C4–2B tumors. Micro-tumors showed severe growth delay or eradication in response to Rad-223, whereas macro-tumors persisted and expanded. The relative inefficacy in controlling large tumors points to application of Rad-223 in secondary prevention of early bone-metastatic disease and regimens co-targeting the tumor core.

Polycaprolactone scaffold and reduced rhBMP-7 dose for the regeneration of critical-sized defects in sheep tibiae

Publisher: Elsevier BV

Date: 12-2013

DOI: 10.1016/J.BIOMATERIALS.2013.09.011

Abstract: The transplantation of autologous bone graft as a treatment for large bone defects has the limitation of harvesting co-morbidity and limited availability. This drives the orthopaedic research community to develop bone graft substitutes. Routinely, supra-physiological doses of bone morphogenetic proteins (BMPs) are applied perpetuating concerns over undesired side effects and cost of BMPs. We therefore aimed to design a composite scaffold that allows maintenance of protein bioactivity and enhances growth factor retention at the implantation site. Critical-sized defects in sheep tibiae were treated with the autograft and with two dosages of rhBMP-7, 3.5 mg and 1.75 mg, embedded in a slowly degradable medical grade poly(ε-caprolactone) (PCL) scaffold with β-tricalcium phosphate microparticles (mPCL-TCP). Specimens were characterised by biomechanical testing, microcomputed tomography and histology. Bridging was observed within 3 months for the autograft and both rhBMP-7 treatments. No significant difference was observed between the low and high rhBMP-7 dosages or between any of the rhBMP-7 groups and autograft implantation. Scaffolds alone did not induce comparable levels of bone formation compared to the autograft and rhBMP-7 groups. In summary, the mPCL-TCP scaffold with the lower rhBMP-7 dose led to equivalent results to autograft transplantation or the high BMP dosage. Our data suggest a promising clinical future for BMP application in scaffold-based bone tissue engineering, lowering and optimising the amount of required BMP.

Hydrogels as Drug Delivery Systems: A Review of Current Characterization and Evaluation Techniques

Publisher: MDPI AG

Date: 07-12-2020

DOI: 10.3390/PHARMACEUTICS12121188

Abstract: Owing to their tunable properties, controllable degradation, and ability to protect labile drugs, hydrogels are increasingly investigated as local drug delivery systems. However, a lack of standardized methodologies used to characterize and evaluate drug release poses significant difficulties when comparing findings from different investigations, preventing an accurate assessment of systems. Here, we review the commonly used analytical techniques for drug detection and quantification from hydrogel delivery systems. The experimental conditions of drug release in saline solutions and their impact are discussed, along with the main mathematical and statistical approaches to characterize drug release profiles. We also review methods to determine drug diffusion coefficients and in vitro and in vivo models used to assess drug release and efficacy with the goal to provide guidelines and harmonized practices when investigating novel hydrogel drug delivery systems.

A Commentary on “Thermo‐responsive polymeric surfaces; control of attachment and detachment of cultured cells” by N. Yamada, T. Okano, H. Sakai, F. Karikusa, Y. Sawasaki, Y. Sakurai (Makromol. Chem