ORCID Profile
0000-0002-1582-5756
Current Organisation
Royal College of Surgeons in Ireland
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Publisher: Elsevier BV
Date: 02-2021
Publisher: Cold Spring Harbor Laboratory
Date: 29-09-2020
DOI: 10.1101/2020.09.29.315317
Abstract: Entosis is a form of non-phagocytic cell-in-cell (CIC) interaction where a living cell enters into another. Tumours show evidence of entosis, however factors controlling entosis remain to be elucidated. Here we find that the death receptor ligand TRAIL is a potent activator of entosis in colon cancer cells. CLEM/3D confocal microscopy analysis revealed ultrastructural features of entosis and subsequent entotic cell death of inner cells upon TRAIL treatment. Induction of entosis and apoptosis by TRAIL were mutually exclusive events but both required the presence of caspase-8. Bax/Bak double knock-out or caspase inhibition altered the fate of inner cells from entotic cell death to survival and escape. Analysis of colorectal cancer tumours showed a significant association between expression levels of TRAIL and CICs. Notably, the presence of CICs in the invasive front regions of colorectal tumours was significantly correlated with adverse patient prognosis.
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.BIOMATERIALS.2017.09.036
Abstract: The clinical translation of bioactive scaffolds for the treatment of large segmental bone defects has remained a challenge due to safety and efficacy concerns as well as prohibitive costs. The design of an implantable, biocompatible and resorbable device, which can fill the defect space, allow for cell infiltration, differentiation and neovascularisation, while also recapitulating the natural repair process and inducing cells to lay down new bone tissue, would alleviate the problems with existing treatments. We have developed a gene-activated scaffold platform using a bone-mimicking collagen hydroxyapatite scaffold loaded with chitosan nanoparticles carrying genes encoding osteogenic (BMP-2) and angiogenic (VEGF) proteins. With a single treatment, protein expression by mesenchymal stem cells (MSCs) seeded onto the scaffold is sustained for up to 28 days and is functional in inducing MSC osteogenesis. The in vivo safety and efficacy of this gene-activated scaffold platform was demonstrated resulting in the successful transfection of host cells, abrogating the requirement for multiple procedures to isolate cells or ex vivo cell culture. Furthermore, the level of bone formation at the exceptionally early time-point of 28 days was comparable to that achieved following recombinant BMP-2 protein delivery after 8 weeks in vivo, without the adverse side effects and at a fraction of the cost. This naturally derived cell-free gene-activated scaffold thus represents a new 'off-the-shelf' product capable of accelerating bone repair in critical-sized bone defects.
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1016/J.SPINEE.2009.02.011
Abstract: In humans, lower back pain is one of the most common causes of morbidity. Many studies implicate degeneration of intervertebral discs as the cause. In the normal intervertebral disc, the nucleus pulposus exerts a hydrostatic pressure against the constraining annulus fibrosus, which allows the disc to maintain flexibility between adjacent vertebrae, while absorbing necessary compressive forces. The nucleus pulposus performs this role because of its hydrophilic gel-like structure. The extracellular matrix of the nucleus pulposus is up to 80% hydrated, as a result of large amounts of the aggregating proteoglycan, chondroitin sulfate proteoglycan (CSPG). This proteoglycan is enmeshed in a randomly orientated network of fine collagen Type II (CT2) fibers. STUDY DESIGN AND PURPOSE: A useful adult tissue-derived stem cell is that from the olfactory mucosa, the organ of smell. These cells, accessible in humans from nasal biopsies, are multipotent and are able to make many cell types from all germ layers. They are easily grown in vitro and can be expanded to large numbers and stored frozen. These qualities indicate the potential for autologous transplantation for disc repair. In this article, using a rat model, we explore the hypothesis that olfactory stem cells can differentiate into a nucleus pulposus chondrocyte phenotype in vitro, as well as in vivo after transplantation into the injured intervertebral disc. Female rats (14 weeks) were anesthetized with xylazine/ketamine. The abdominal wall was shaved and injected with local anesthetic (lidocaine) before incision. The ventral part of the lumbar spine, including two intervertebral discs, was exposed. Disc degeneration was then induced in the two exposed discs by needle aspiration of the nucleus pulposus. The prominent spina iliaca posterior superior was used as an anatomical landmark for identification of the first disc. Two weeks later, one injured intervertebral disc was exposed in a second, similar, surgery and 20,000 olfactory neurosphere-derived cells were transplanted with a 25-G needle. In vitro induction of nucleus pulposus chondrocyte phenotype is measured by the percentage of cells expressing CT2 and CSPG. In vivo, a successful outcome is evidence of engraftment of donor-derived cells and their expression of CT2 and CSPG. In this article, we tested two hypotheses: the first that progenitor cells within olfactory neurospheres could be induced to express markers distinctive of the nucleus pulposus when placed in vitro in a coculture experiment. The second hypothesis tested the same induction in genetically labeled transplanted cells within damaged vertebral discs in vivo. The two markers measured are those held by current literature to engender the necessary cushioning characteristics of nucleus pulposus, CT2 and CSPG. Our experiments demonstrated virtually 100% induction of these two markers in vitro. Also, this induction was achieved in donor-derived cells after delivery to the nucleus pulposus region of animals whose discs had previously been lesioned 2 weeks before transplant. These results provide a rationale for moving toward more extensive larger animal studies for assessment of regeneration before human trials where relief of symptoms can be more easily assessed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC03092K
Abstract: Novel Ln( iii )-based hiphilic complexes with potential application as luminescent and MRI contrast agents, which self-assemble in aqueous solution into spherical micelles, are presented.
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.ACTBIO.2018.02.004
Abstract: 3D scaffold-based in vitro cell culturing is a recent technological advancement in cancer research bridging the gap between conventional 2D culture and in vivo tumours. The main challenge in treating neuroblastoma, a paediatric cancer of the sympathetic nervous system, is to combat tumour metastasis and resistance to multiple chemotherapeutic drugs. The aim of this study was to establish a physiologically relevant 3D neuroblastoma tissue-engineered system and explore its therapeutic relevance. Two neuroblastoma cell lines, chemotherapeutic sensitive Kelly and chemotherapeutic resistant KellyCis83 were cultured in a 3D in vitro model on two collagen-based scaffolds containing either glycosaminoglycan (Coll-GAG) or nanohydroxyapatite (Coll-nHA) and compared to 2D cell culture and an orthotopic murine model. Both neuroblastoma cell lines actively infiltrated the scaffolds and proliferated displaying >100-fold increased resistance to cisplatin treatment when compared to 2D cultures, exhibiting chemosensitivity similar to orthotopic xenograft in vivo models. This model demonstrated its applicability to validate miRNA-based gene delivery. The efficacy of liposomes bearing miRNA mimics uptake and gene knockdown was similar in both 2D and 3D in vitro culturing models highlighting the proof-of-principle for the applicability of 3D collagen-based scaffolds cell system for validation of miRNA function. Collectively, this data shows the successful development and characterisation of a physiologically relevant, scaffold-based 3D tissue-engineered neuroblastoma cell model, strongly supporting its value in the evaluation of chemotherapeutics, targeted therapies and investigation of neuroblastoma pathogenesis. While neuroblastoma is the specific disease being focused upon, the platform may have multi-functionality beyond this tumour type. Traditional 2D cell cultures do not completely capture the 3D architecture of cells and extracellular matrix contributing to a gap in our understanding of mammalian biology at the tissue level and may explain some of the discrepancies between in vitro and in vivo results. Here, we demonstrated the successful development and characterisation of a physiologically relevant, scaffold-based 3D tissue-engineered neuroblastoma cell model, strongly supporting its value in the evaluation of chemotherapeutics, targeted therapies and investigation of neuroblastoma pathogenesis. The ability to test drugs in this reproducible and controllable tissue-engineered model system will help reduce the attrition rate of the drug development process and lead to more effective and tailored therapies. Importantly, such 3D cell models help to reduce and replace animals for pre-clinical research addressing the principles of the 3Rs.
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1111/JTH.15794
Abstract: Breast cancer results in a three- to four-fold increased risk of venous thromboembolism (VTE), which is associated with reduced patient survival. Despite this, the mechanisms underpinning breast cancer-associated thrombosis remain poorly defined. Tumor cells can trigger endothelial cell (EC) activation resulting in increased von Willebrand factor (VWF) secretion. Importantly, elevated plasma VWF levels constitute an independent biomarker for VTE risk. Moreover, in a model of melanoma, treatment with low molecular weight heparin (LMWH) negatively regulated VWF secretion and attenuated tumor metastasis. To investigate the role of VWF in breast cancer metastasis and examine the effect of LMWH in modulating EC activation and breast tumor transmigration. von Willebrand factor levels were measured by ELISA. Primary ECs were used to assess tumor-induced activation, angiogenesis, tumor adhesion, and transendothelial migration. Patients with metastatic breast cancer have markedly elevated plasma VWF:Ag levels that also correlate with poorer survival. MDA-MB-231 and MCF-7 breast cancer cells induce secretion of VWF, angiopoietin-2, and osteoprotegerin from ECs, which is further enhanced by the presence of platelets. Vascular endothelial growth factor-A (VEGF-A) plays an important role in modulating breast cancer-induced VWF release. Moreover, VEGF-A from breast tumor cells also contributes to a pro-angiogenic effect on ECs. VWF multimers secreted from ECs, in response to tumor-VEGF-A, mediate adhesion of breast tumor cells along the endothelium. LMWH inhibits VWF-breast tumor adhesion and transendothelial migration. Our findings highlight the significant crosstalk between tumor cells and the endothelium including increased VWF secretion which may contribute to tumor metastasis.
Publisher: MDPI AG
Date: 12-12-2019
Abstract: Glioblastoma (GBM) is the most common primary brain tumor with no available cure. As previously described, seliciclib, a first-generation cyclin-dependent kinase (CDK) inhibitor, down-regulates the anti-apoptotic protein, Mcl-1, in GBM, thereby sensitizing GBM cells to the apoptosis-inducing effects of the death receptor ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, we have assessed the efficacy of seliciclib when delivered in combination with the antibody against human death receptor 5, drozitumab, in clinically relevant patient-derived xenograft (PDX) models of GBM. A reduction in viability and significant levels of apoptosis were observed in vitro in human GBM neurospheres following treatment with seliciclib plus drozitumab. While the co-treatment strategy induced a similar effect in PDX models, the dosing regimen required to observe seliciclib-targeted responses in the brain, resulted in lethal toxicity in 45% of animals. Additional studies showed that the second-generation CDK inhibitor, CYC065, with improved potency in comparison to seliciclib, induced a significant decrease in the size of human GBM neurospheres in vitro and was well tolerated in vivo, upon administration at clinically relevant doses. This study highlights the continued need for robust pre-clinical assessment of promising treatment approaches using clinically relevant models.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.AUTNEU.2016.08.015
Abstract: Autonomic dysreflexia is a common complication after high level spinal cord injury and can be life-threatening. We have previously shown that the acute transplantation of olfactory ensheathing cells into the lesion site of rats transected at the fourth thoracic spinal cord level reduced autonomic dysreflexia up to 8weeks after spinal cord injury. This beneficial effect was correlated with changes in the morphology of sympathetic preganglionic neurons despite the olfactory cells surviving no longer than 3weeks. Thus the transitory presence of olfactory ensheathing cells at the injury site initiated long-term functional as well as morphological changes in the sympathetic preganglionic neurons. The primary aim of the present study was to evaluate whether olfactory ensheathing cells survive after transplantation within the parenchyma close to sympathetic preganglionic neurons and whether, in this position, they still reduce the duration of autonomic dysreflexia and modulate sympathetic preganglionic neuron morphology. The second aim was to quantify the density of synapses on the somata of sympathetic preganglionic neurons with the hypothesis that the reduction of autonomic dysreflexia requires synaptic changes. As a third aim, we evaluated the cell type-specificity of olfactory ensheathing cells by comparing their effects with a control group transplanted with fibroblasts. Animals transplanted with OECs had a faster recovery from hypertension induced by colorectal distension at 6 and 7weeks but not at 8weeks after T4 spinal cord transection. Olfactory ensheathing cells survived for at least 8weeks and were observed adjacent to sympathetic preganglionic neurons whose overall number of primary dendrites was reduced and the synaptic density on the somata increased, both caudal to the lesion site. Our results showed a long term cell type-specific effects of olfactory ensheathing cells on sympathetic preganglionic neurons morphology and on the synaptic density on their somata, and a transient cell type-specific reduction of autonomic dysreflexia.
Publisher: Rockefeller University Press
Date: 21-09-2021
Abstract: Entosis is a form of nonphagocytic cell-in-cell (CIC) interaction where a living cell enters into another. Tumors show evidence of entosis however, factors controlling entosis remain to be elucidated. Here, we find that besides inducing apoptosis, TRAIL signaling is a potent activator of entosis in colon cancer cells. Initiation of both apoptosis and entosis requires TRAIL receptors DR4 and DR5 however, induction of apoptosis and entosis erges at caspase-8 as its structural presence is sufficient for induction of entosis but not apoptosis. Although apoptosis and entosis are morphologically and biochemically distinct, knockout of Bax and Bak, or inhibition of caspases, also inhibits entotic cell death and promotes survival and release of inner cells. Analysis of colorectal cancer tumors reveals a significant association between TRAIL signaling and CIC structures. Finally, the presence of CIC structures in the invasive front regions of colorectal tumors shows a strong correlation with adverse patient prognosis.
Publisher: SAGE Publications
Date: 25-10-2018
Abstract: Injectable hydrogels that aim to mechanically stabilise the weakened left ventricle wall to restore cardiac function or to deliver stem cells in cardiac regenerative therapy have shown promising data. However, the clinical translation of hydrogel-based therapies has been limited due to difficulties injecting them through catheters. We have engineered a novel catheter, Advanced Materials Catheter (AMCath), that overcomes translational hurdles associated with delivering fast-gelling covalently cross-linked hyaluronic acid hydrogels to the myocardium. We developed an experimental technique to measure the force required to inject such hydrogels and determined the mechanical/viscoelastic properties of the resulting hydrogels. The preliminary in vivo feasibility of delivering fast-gelling hydrogels through AMCath was demonstrated by accessing the porcine left ventricle and showing that the hydrogel was retained in the myocardium post-injection (three 200 μL injections delivered, 192, 204 and 183 μL measured). However, the mechanical properties of the hydrogels were reduced by passage through AMCath (≤20.62% reduction). We have also shown AMCath can be used to deliver cardiopoietic adipose-derived stem cell-loaded hydrogels without compromising the viability (80% viability) of the cells in vitro. Therefore, we show that hydrogel/catheter compatibility issues can be overcome as we have demonstrated the minimally invasive delivery of a fast-gelling covalently cross-linked hydrogel to the beating myocardium.
Publisher: IEEE
Date: 06-2009
Publisher: Wiley
Date: 12-2012
Publisher: Wiley
Date: 29-06-2020
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.EXPNEUROL.2017.05.006
Abstract: The two neuronal populations in the cortex, pyramidal neurons and interneurons, can be separated based on neurotransmitter identity, however, within this segregation a large degree of ersity exists. Investigations into the molecular ersity of neurons are impeded by the inability to isolate cell populations born at different times for gene expression analysis. Developing interneurons may be distinguished by the expression of Glutamic Acid Decarboxylase-67 (GAD67). Neuronal birthdating using nucleoside analogs is an effective means of identifying coetaneous interneurons. Using these two features, neurotransmitter identity and birthdating, we have developed a method to isolate migrating interneurons using fluorescent-activated cell sorting (FACS) for RNA extraction and gene expression analysis. We utilized 5-ethynyl-2'-deoxyuridine (EdU) to birthdate interneuron cohorts and the GAD67 knock-in GFP transgenic mice to identify interneurons. In combination, we achieved simultaneous detection of GFP and EdU signals during FACS sorting of coetaneous interneurons with minimum loss of RNA integrity. RNA quality was deemed to be satisfactory by quantitative polymerase chain reaction (qPCR) for the interneuron-specific transcript Gad67.
Publisher: Wiley
Date: 25-11-2021
Abstract: After spinal cord injury (SCI), tissue engineering scaffolds offer a potential bridge for regeneration across the lesion and support repair through proregenerative signaling. Ideal biomaterial scaffolds that mimic the physicochemical properties of native tissue have the potential to provide innate trophic signaling while also minimizing damaging inflammation. To address this challenge, taking cues from the spinal cord's structure, the proregenerative signaling capabilities of native cord components are compared in vitro. A synergistic mix of collagen‐IV and fibronectin (Coll‐IV/Fn) is found to optimally enhance axonal extension from neuronal cell lines (SHSY‐5Y and NSC‐34) and induce morphological features typical of quiescent astrocytes. This optimal composition is incorporated into hyaluronic acid scaffolds with aligned pore architectures but varying stiffnesses (0.8–3 kPa). Scaffolds with biomimetic mechanical properties ( kPa), functionalized with Coll‐IV/Fn, not only modulate primary astrocyte behavior but also stimulate the production of anti‐inflammatory cytokine IL‐10 in a stiffness‐dependent manner. Seeded SHSY‐5Y neurons generate distributed neuronal networks, while softer biomimetic scaffolds promote axonal outgrowth in an ex vivo model of axonal regrowth. These results indicate that the interaction of stiffness and biomaterial composition plays an essential role in vitro in generating repair‐critical cellular responses and demonstrates the potential of biomimetic scaffold design.
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.JCONREL.2018.05.022
Abstract: Gene-activated scaffolds have been shown to induce controlled, sustained release of functional transgene both in vitro and in vivo. Bone morphogenetic proteins (BMPs) are potent mediators of osteogenesis however we found that the delivery of plasmid BMP-2 (pBMP-2) alone was not sufficient to enhance bone formation. Therefore, the aim of this study was to assess if the use of a series of modified BMP-2 plasmids could enhance the functionality of a pBMP-2 gene-activated scaffold and ultimately improve bone regeneration when implanted into a critical sized bone defect in vivo. A multi-cistronic plasmid encoding both BMP-2 and BMP-7 (BMP-2/7) was employed as was a BMP-2-Advanced plasmid containing a highly truncated intron sequence. With both plasmids, the highly efficient cytomegalovirus (CMV) promoter sequence was used. However, as there have been reports that the elongated factor 1-α promoter is more efficient, particularly in stem cells, a BMP-2-Advanced plasmid containing the EF1α promoter was also tested. Chitosan nanoparticles (CS) were used to deliver each plasmid to MSCs and induced transient up-regulation of BMP-2 protein expression, in turn significantly enhancing MSC-mediated osteogenesis when compared to untreated controls (p < 0.001). When incorporated into a bone mimicking collagen-hydroxyapatite scaffold, the BMP-2-Advanced plasmid, under the control of the CMV promotor, induced MSCs to produce approximately 2500 μg of calcium per scaffold, significantly higher (p < 0.001) than all other groups. Just 4 weeks post-implantation in vivo, this cell-free gene-activated scaffold induced significantly more bone tissue formation compared to a pBMP-2 gene-activated scaffold (p < 0.001) as indicated by microCT and histomorphometry. Immunohistochemistry revealed that the BMP-2-Advanced plasmid accelerated differentiation of osteoprogenitor cells to mature osteoblasts, thus causing rapid healing of the bone defects. This study confirms that optimising the plasmid construct can enhance the functionality of gene-activated scaffolds and translate to accelerated bone formation in a critical sized defect.
Publisher: Wiley
Date: 12-2012
Publisher: American Chemical Society (ACS)
Date: 28-03-2018
DOI: 10.1021/ACS.MOLPHARMACEUT.8B00044
Abstract: The field of tissue engineering is increasingly recognizing that gene therapy can be employed for modulating in vivo cellular response thereby guiding tissue regeneration. However, the field lacks a versatile and biocompatible gene delivery platform capable of efficiently delivering transgenes to mesenchymal stem cells (MSCs), a cell type often refractory to transfection. Herein, we describe the extensive and systematic exploration of three architectural variations of star-shaped poly(l-lysine) polypeptide (star-PLL) with varying number and length of poly(l-lysine) arms as potential nonviral gene delivery vectors for MSCs. We demonstrate that star-PLL vectors are capable of self-assembling with pDNA to form stable, cationic nanomedicines. Utilizing high content screening, live cell imaging, and mechanistic uptake studies we confirm the intracellular delivery of pDNA by star-PLLs to MSCs is a rapid process, which likely proceeds via a clathrin-independent mechanism. We identify a star-PLL composition with 64 poly(l-lysine) arms and five l-lysine subunits per arm as a particularly efficient vector that is capable of delivering both reporter genes and the therapeutic transgenes bone morphogenetic protein-2 and vascular endothelial growth factor to MSCs. This composition facilitated a 1000-fold increase in transgene expression in MSCs compared to its linear analogue, linear poly(l-lysine). Furthermore, it demonstrated comparable transgene expression to the widely used vector polyethylenimine using a lower pDNA dose with significantly less cytotoxicity. Overall, this study illustrates the ability of the star-PLL vectors to facilitate efficient, nontoxic nucleic acid delivery to MSCs thereby functioning as an innovative nanomedicine platform for tissue engineering applications.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.BIOMATERIALS.2016.01.065
Abstract: Today, chronic respiratory disease is one of the leading causes of mortality globally. Epithelial dysfunction can play a central role in its pathophysiology. The development of physiologically-representative in vitro model systems using tissue-engineered constructs might improve our understanding of epithelial tissue and disease. This study sought to engineer a bilayered collagen-hyaluronate (CHyA-B) scaffold for the development of a physiologically-representative 3D in vitro tracheobronchial epithelial co-culture model. CHyA-B scaffolds were fabricated by integrating a thin film top-layer into a porous sub-layer with lyophilisation. The film layer firmly connected to the sub-layer with delamination occurring at stresses of 12-15 kPa. Crosslinked scaffolds had a compressive modulus of 1.9 kPa and mean pore diameters of 70 μm and 80 μm, depending on the freezing temperature. Histological analysis showed that the Calu-3 bronchial epithelial cell line attached and grew on CHyA-B with adoption of an epithelial monolayer on the film layer. Immunofluorescence and qRT-PCR studies demonstrated that the CHyA-B scaffolds facilitated Calu-3 cell differentiation, with enhanced mucin expression, increased ciliation and the formation of intercellular tight junctions. Co-culture of Calu-3 cells with Wi38 lung fibroblasts was achieved on the scaffold to create a submucosal tissue analogue of the upper respiratory tract, validating CHyA-B as a platform to support co-culture and cellular organisation reminiscent of in vivo tissue architecture. In summary, this study has demonstrated that CHyA-B is a promising tool for the development of novel 3D tracheobronchial co-culture in vitro models with the potential to unravel new pathways in drug discovery and drug delivery.
Publisher: Wiley
Date: 14-09-2022
Abstract: Diabetic foot ulcers (DFUs) are chronic wounds sustained by pathological fibroblasts and aberrant extracellular matrix (ECM). Porous collagen‐based scaffolds (CS) have shown clinical promise for treating DFUs but may benefit from functional enhancements. Our previous work showed fibroblasts differentiated from induced pluripotent stem cells are an effective source of new ECM mimicking fetal matrix, which notably promotes scar‐free healing. Likewise, functionalizing CS with this rejuvenated ECM shows potential for DFU healing. Herein, an approach to DFU healing is demonstrated for the first time using biopsied cells from DFU patients, reprogramming those cells, and functionalizing CS with patient‐specific ECM as a personalized acellular tissue‐engineered scaffold. A two‐pronged approach is taken: 1) direct ECM blending into scaffold fabrication, and 2) seeding scaffolds with reprogrammed fibroblasts for ECM deposition followed by decellularization. The decellularization approach reduces cell number requirements and maintains naturally deposited ECM proteins. Both approaches show enhanced ECM deposition from DFU fibroblasts. Decellularized scaffolds additionally enhance glycosaminoglycan deposition and subsequent vascularization. Finally, reprogrammed ECM scaffolds from patient‐matched DFU fibroblasts outperform those from healthy fibroblasts in several metrics, suggesting ECM is in fact able to redirect resident pathological fibroblasts in DFUs toward healing, and a patient‐specific ECM signature may be beneficial.
Publisher: Wiley
Date: 20-10-2017
DOI: 10.1002/JBM.B.33802
Abstract: Localized delivery of stem cells is potentially a promising therapeutic strategy for regenerating damaged myocardium. Many studies focus on limiting the biologic component of cell loss, but few address the contribution of mechanical factors. This study investigates optimal parameters for retaining the largest volume of cell loaded hydrogels post intramyocardial injection, without compromising cell viability. In vitro, hydrogel was injected into porcine hearts using various needle designs. Hydrogel retention and distribution pattern was then determined. The two most promising needles were then investigated to understand the effect of needle geometry on stem cell viability. The needle to best impact cell viability was then used to investigate the effect of differing hydrogels on retention and distribution. Three-dimensional experimental modeling revealed needles with smaller diameter's to have greater poloxamer 407 hydrogel retention. No difference in retention existed among various needle designs of similar gauge, despite differences in bolus geometries. When hMSC's, embedded in fibrin hydrogel, were injected through helical and 26G bevel needles no difference in the percent of live cells was seen at 48 h. However, the helical group had almost half the metabolic activity of the 26G bevel group at both time points, and had a significant decline in the percent of live cells from 24 to 48 h. Varying gel type resulted in significantly more alginate being retained in the tissue in comparison to fibrin or poloxamer hydrogels. In conclusion, mechanical properties of injected hydrogels, and the diameter of the needle used, highly influences the volume of hydrogel retained. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2618-2629, 2017.
Publisher: Wiley
Date: 13-11-2018
DOI: 10.1002/JCB.28015
Abstract: Cripto‐1 has been implicated in a number of human cancers. Although there is high potential for a role of Cripto‐1 in glioblastoma multiforme (GBM) pathogenesis and progression, few studies have tried to define its role in GBM. These studies were limited in that Cripto‐1 expression was not studied in detail in relation to markers of cancer initiation and progression. Therefore, these correlative studies allowed limited interpretation of Criptos‐1's effect on the various aspects of GBM development using the U87 GBM cell line. In this study, we sought to delineate the role of Cripto‐1 in facilitating pathogenesis, stemness, proliferation, invasion, migration and angiogenesis in GBM. Our findings show that upon overexpressing Cripto‐1 in U87 GBM cells, the stemness markers Nanog, Oct4, Sox2, and CD44 increased expression. Similarly, an increase in Ki67 was observed demonstrating Cripto‐1's potential to induce cellular proliferation. Likewise, we report a novel finding that increased expression of the markers of migration and invasion, Vimentin and Twist, correlated with upregulation of Cripto‐1. Moreover, Cripto‐1 exposure led to VEGFR‐2 overexpression along with higher tube formation under conditions promoting endothelial growth. Taken together our results support a role for Cripto‐1 in the initiation, development, progression, and maintenance of GBM pathogenesis. The data presented here are also consistent with a role for Cripto‐1 in the re‐growth and invasive growth in GBM. This highlights its potential use as a predictive and diagnostic marker in GBM as well as a therapeutic target.
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.ACTBIO.2017.02.031
Abstract: In order to identify the mechanisms by which skeletal maturity alters the mechanosensitivity of mesenchymal stromal cells (MSCs) and, the implications for osteogenesis and angiogenesis during bone formation, we compared the response of MSCs derived from children and skeletally-mature healthy adults cultured on soft and stiff collagen-coated polyacrylamide substrates. MSCs from children were more mechanosensitive, showing enhanced angiogenesis and osteogenesis on stiff substrates as indicated by increased endothelial tubule formation, PGF production, nuclear-translocation of YAP, ALP activity and mineralisation. To examine these mechanisms in more detail, a customised PCR array identified an age-dependent, stiffness-induced upregulation of NOX1, VEGFR1, VEGFR2, WIF1 and, of particular interest, JNK3 in cells from children compared to adults. When JNK3 activity was inhibited, a reduction in stiffness-induced driven osteogenesis was observed - suggesting that JNK3 might serve as a novel target for recapitulating the enhanced regenerative potential of children in adults suffering from bone degeneration. We investigated the age-associated changes in the capacity of MSCs for bone regeneration involving the mechanosensitive signalling pathways, which reduce the ability of adult cells to respond to biophysical cues in comparison to cells from children, who are still undergoing bone development. Our results offer new insights into the mechanobiology of MSCs and sheds new light on age-altered mechanosensitivity and, on why children have such an immense capacity to regenerate their skeletal system. We have identified the mechanisms by which skeletal maturity alters the mechanosensitivity of mesenchymal stromal cells and an age-dependent, stiffness-induced upregulation of a number of prominent genes including, most notably, JNK3 in children cells, thus suggesting its potential to promote enhanced bone repair.
Publisher: MDPI AG
Date: 15-09-2011
No related grants have been discovered for Brenton Cavanagh.