ORCID Profile
0000-0002-2581-1454
Current Organisation
Thermo Fisher Scientific Inc
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Publisher: American Chemical Society (ACS)
Date: 03-11-2010
DOI: 10.1021/BM101078C
Abstract: Semicrystalline poly(l-lactide-co-ε-caprolactone) (P(LLA-CL)) was used to produce electrospun fibers with diameters on the subcellular scale. P(LLA-CL) was chosen because it is biocompatible and its chemical and physical properties are easily tunable. The use of a rotating wire mandrel as a collection device in the electrospinning process, along with high collection speeds, was used to align electrospun fibers. Upon removal of the fibers from the mandrel, the fibers shrunk in length, producing a crimp pattern characteristic of collagen fibrils in soft connective tissues. The crimping effect was determined to be a result of the residual stresses resident in the fibers due to the fiber alignment process and the difference between the operating temperature (T(op)) and the glass-transition temperature (T(g)) of the polymer. The electrospun fibers could be induced to crimp by adjusting the operating temperature to be greater than that of the polymer glass-transition temperature. Moreover, the crimped fibers exhibited a toe region in their stress-strain profile that is characteristic of collagen present in tendons and ligaments. The crimp pattern was retained during in vitro degradation over 4 weeks. Primary bovine fibroblasts seeded onto these crimped fibers attached, proliferated, and deposited extracellular matrix (ECM) molecules on the surface of the fiber mats. These self-crimping fibers hold great promise for use in tissue engineering scaffolds for connective tissues that require fibers similar in structure to that of crimped collagen fibrils.
Publisher: Mary Ann Liebert Inc
Date: 05-2012
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.ACTBIO.2012.07.012
Abstract: The aim of this study was to fabricate a fibrous scaffold that closely resembled the micro-structural architecture and mechanical properties of collagen fibres found in the anterior cruciate ligament (ACL). To achieve this aim, fibrous scaffolds were made by electrospinning L-lactide based polymers. L-Lactide was chosen primarily due to its demonstrated biocompatibility, biodegradability and high modulus. The electrospun fibres were collected in tension on a rotating wire mandrel. Upon treating these fibres in a heated aqueous environment, they possessed a crimp-like pattern having a wavelength and litude similar to that of native ACL collagen. Of the polymer fibre scaffolds studied, those made from poly(L-lactide-co-D,L-lactide) PLDLA exhibited the highest modulus and were also the most resilient to in vitro hydrolytic degradation, undergoing a slight decrease in modulus compared to the other polymeric fibres over a 6 month period. Bovine fibroblasts seeded on the wavy, crimp-like PLDLA fibres attached, proliferated and deposited extracellular matrix (ECM) molecules on the surface of the fibrous scaffold. In addition, the deposited ECM exhibited bundle formation that resembled the fascicles found in native ACL. These findings demonstrate the importance of replicating the geometric microenvironment in developing effective tissue engineering scaffolds.
Publisher: Wiley
Date: 08-07-2020
Publisher: Mary Ann Liebert Inc
Date: 08-2011
Publisher: Wiley
Date: 11-07-2016
DOI: 10.1002/BIT.26040
Abstract: Human skin-derived precursor cells (hSKPs) are multipotent adult stem cells found in the dermis of human skin. Incorporation of hSKPs into split-thickness skin grafts (STSGs), the current gold standard to treat severe burns or tissue resections, has been proposed as a treatment option to enhance skin wound healing and tissue function. For this approach to be clinically viable substantial quantities of hSKPs are required, which is the rate-limiting step, as only a few thousand hSKPs can be isolated from an autologous skin biopsy without causing donor site morbidity. In order to produce sufficient quantities of clinically viable cells, we have developed a bioprocess capable of expanding hSKPs as aggregates in stirred suspension bioreactors (SSBs). In this study, we found hSKPs from adult donors to expand significantly more (P < 0.05) at 60 rpm in SSBs than in static cultures. Furthermore, the utility of the SSBs, at 60 rpm is demonstrated by serial passaging of hSKPs from a small starting population, which can be isolated from an autologous skin biopsy without causing donor site morbidity. At 60 rpm, aggregates were markedly smaller and did not experience oxygen diffusional limitations, as seen in hSKPs cultured at 40 rpm. While hSKPs also grew at 80 rpm (0.74 Pa) and 100 rpm (1 Pa), they produced smaller aggregates due to high shear stress. The pH of the media in all the SSBs was closer to biological conditions and significantly different (P < 0.05) from static cultures, which recorded acidic pH conditions. The nutrient concentrations of the media in all the SSBs and static cultures did not drop below acceptable limits. Furthermore, there was no significant build-up of waste products to limit hSKP expansion in the SSBs. In addition, hSKP markers were maintained in the 60 rpm SSB as demonstrated by immunocytochemistry. This method of growing hSKPs in a batch culture at 60 rpm in a SSB represents an important first step in developing an automated bioprocess to produce substantial numbers of clinically viable hSKPs aimed at regenerating the dermis to improve healing of severe skin wounds. Biotechnol. Bioeng. 2016 : 2725-2738. © 2016 Wiley Periodicals, Inc.
Publisher: IOP Publishing
Date: 31-08-2020
Publisher: Wiley
Date: 07-04-2009
DOI: 10.1002/JBM.A.32472
Abstract: Herein we report on the development and characterization of a biodegradable composite scaffold for ligament tissue engineering based on the fundamental morphological features of the native ligament. An aligned fibrous component was used to mimic the fibrous collagen network and a hydrogel component to mimic the proteoglycan-water matrix of the ligament. The composite scaffold was constructed from cell-adherent, base-etched, electrospun poly(epsilon-caprolactone-co-D,L-lactide) (PCLDLLA) fibers embedded in a noncell-adherent photocrosslinked N-methacrylated glycol chitosan (MGC) hydrogel seeded with primary ligament fibroblasts. Base etching improved cellular adhesion to the PCLDLLA material. Cells within the MGC hydrogel remained viable (72 +/- 4%) during the 4-week culture period. Immunohistochemistry staining revealed ligament ECM markers collagen type I, collagen type III, and decorin organizing and accumulating along the PCLDLLA fibers within the composite scaffolds. On the basis of these results, it was determined that the composite scaffold design was a viable alternative to the current approaches used for ligament tissue engineering and merits further study.
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.ACTBIO.2012.06.016
Abstract: The aim of this study was to determine the influence of a crimp-like microarchitecture within electrospun polymer scaffolds on fibroblast extracellular matrix (ECM) production when cultured under dynamic conditions. Electrospun poly(L-lactide-co-D,L-lactide) scaffolds possessing a wave pattern similar to collagen crimp ( litude: 5 μm and wavelength: 46 μm) were seeded with bovine fibroblasts and mechanically stimulated under dynamic uniaxial tension. The effect of strain litude (5%, 10% and 20%) was investigated in a short-term stimulation study. The 10% strain litude in the stimulated crimp-like fibre scaffold increased only collagen synthesis, while the 20% strain litude increased both collagen and sulphated proteoglycan synthesis compared to stimulated uncrimped (straight) fibre scaffolds and unloaded controls (crimp-like static fibre scaffolds). Alternatively, mechanical stimulation of fibroblasts seeded on uncrimped fibre scaffolds induced significant fibroblast proliferation compared to the stimulated crimp-like fibre scaffolds and no-load controls. Long-term, dynamic mechanical stimulation of fibroblasts seeded on crimp-like fibre scaffolds at 10% strain litude resulted in significantly up-regulated collagen accumulation and down-regulated sulphated proteoglycan accumulation. Additionally, the fibroblasts seeded on dynamically stimulated crimp-like fibre scaffolds appeared to form bundles that resembled fascicles, a characteristic hierarchical feature of the native ligament. Our findings demonstrate that fibroblasts seeded on crimp-like fibrous scaffolds respond more favourably (increased ECM synthesis and fascicle formation) to dynamic mechanical loading compared to those grown on scaffolds containing uncrimped (straight) fibres.
No related grants have been discovered for Denver Surrao.