350 results found
LaPointe VLS, Verpoorte A, Stevens MM, 2013, The changing integrin expression and a role for integrin beta 8 in the chondrogenic differentiation of mesenchymal stem cells, PLoS ONE, Vol: 8, Pages: 1-13, ISSN: 1932-6203
Many cartilage tissue engineering approaches aim to differentiate human mesenchymal stem cells (hMSCs) into chondrocytes and develop cartilage in vitro by targeting cell-matrix interactions. We sought to better inform the design of cartilage tissue engineering scaffolds by understanding how integrin expression changes during chondrogenic differentiation. In three models of in vitro chondrogenesis, we studied the temporal change of cartilage phenotype markers and integrin subunits during the differentiation of hMSCs. We found that transcript expression of most subunits was conserved across the chondrogenesis models, but was significantly affected by the time-course of differentiation. In particular, ITGB8 was up-regulated and its importance in chondrogenesis was further established by a knockdown of integrin β8, which resulted in a non-hyaline cartilage phenotype, with no COL2A1 expression detected. In conclusion, we performed a systematic study of the temporal changes of integrin expression during chondrogenic differentiation in multiple chondrogenesis models, and revealed a role for integrin β8 in chondrogenesis. This work enhances our understanding of the changing adhesion requirements of hMSCs during chondrogenic differentiation and underlines the importance of integrins in establishing a cartilage phenotype.
Lim EH, Sardinha JP, Myers S, et al., 2013, Latent transforming growth factor-beta1 functionalised electrospun scaffolds promote human cartilage differentiation: Towards an engineered cartilage construct, Archives of Plastic Surgery, Vol: 40, Pages: 676-686, ISSN: 2234-6163
Background To overcome the potential drawbacks of a short half-life and dose-related adverse effects of using active transforming growth factor-beta 1 for cartilage engineering, a cell-mediated latent growth factor activation strategy was developed incorporating latent transforming growth factor-β1 (LTGF) into an electrospun poly(L-lactide) scaffold. Methods The electrospun scaffold was surface modified with NH3 plasma and biofunctionalised with LTGF to produce both random and orientated biofunctionalised electrospun scaffolds. Scaffold surface chemical analysis and growth factor bioavailability assays were performed. In vitro biocompatibility and human nasal chondrocyte gene expression with these biofunctionalised electrospun scaffold templates were assessed. In vivo chondrogenic activity and chondrocyte gene expression were evaluated in athymic rats. Results Chemical analysis demonstrated that LTGF anchored to the scaffolds was available for enzymatic, chemical and cell activation. The biofunctionalised scaffolds were non-toxic. Gene expression suggested chondrocyte re-differentiation after 14 days in culture. By 6 weeks, the implanted biofunctionalised scaffolds had induced highly passaged chondrocytes to re-express Col2A1 and produce type II collagen. Conclusions We have demonstrated a proof of concept for cell-mediated activation of anchored growth factors using a novel biofunctionalised scaffold in cartilage engineering. This presents a platform for development of protein delivery systems and for tissue engineering. © 2013 The Korean Society of Plastic and Reconstructive Surgeons.
Tang M, Purcell M, Steele JAM, et al., 2013, Porous Copolymers of epsilon-Caprolactone as Scaffolds for Tissue Engineering, MACROMOLECULES, Vol: 46, Pages: 8136-8143, ISSN: 0024-9297
de la Rica R, Stevens MM, 2013, Plasmonic ELISA for the detection of analytes at ultralow concentrations with the naked eye, NATURE PROTOCOLS, Vol: 8, Pages: 1759-1764, ISSN: 1754-2189
Accardi MA, McCullen SD, Callanan A, et al., 2013, Effects of fiber orientation on the frictional properties and damage of regenerative articular cartilage surfaces, Tissue Engineering: Parts A, B, and C, Vol: 19, Pages: 2300-2310, ISSN: 1937-3368
Articular cartilage provides a low-friction, wear-resistant surface for diarthrodial joints. Due to overloading and overuse, articular cartilage is known to undergo significant wear and degeneration potentially resulting in osteoarthritis (OA). Regenerative medicine strategies offer a promising solution for the treatment of articular cartilage defects and potentially localized early OA. Such strategies rely on the development of materials to restore some aspects of cartilage. In this study, microfibrous poly(ɛ-caprolactone) scaffolds of varying fiber orientations (random and aligned) were cultured with bovine chondrocytes for 4 weeks in vitro, and the mechanical and frictional properties were evaluated. Mechanical properties were quantified using unconfined compression and tensile testing techniques. Frictional properties were investigated at physiological compressive strains occurring in native articular cartilage. Scaffolds were sheared along the fiber direction, perpendicular to the fiber direction and in random orientation. The evolution of damage as a result of shear was evaluated via white light interferometry and scanning electron microscopy. As expected, the fiber orientation strongly affected the tensile properties as well as the compressive modulus of the scaffolds. Fiber orientation did not significantly affect the equilibrium frictional coefficient, but it was, however, a key factor in dictating the evolution of surface damage on the surface. Scaffolds shear tested perpendicular to the fiber orientation displayed the highest surface damage. Our results suggest that the fiber orientation of the scaffold implanted in the joint could strongly affect its resistance to damage due to shear. Scaffold fiber orientation should thus be carefully considered when using microfibrous scaffolds.
Boonrungsiman S, Fearn S, Gentleman E, et al., 2013, Correlative spectroscopy of silicates in mineralised nodules formed from osteoblasts, Nanoscale, Vol: 5, Pages: 7544-7551, ISSN: 2040-3372
Silicon supplementation has been shown to play an important role in skeleton development, however, the potential role that silicon plays in mediating bone formation, and an understanding of where it might localise in the resulting bone tissue remain elusive. An improved understanding of these processes could have important implications for treating pathological mineralisation. A key aspect of defining the role of silicon in bone is to characterise its distribution and coordination environment, however, there is currently almost no information available on either. We have combined a sample-preparation method that simultaneously preserved mineral, ions, and the extracellular matrix (ECM) with secondary ion mass spectroscopy (SIMS) and electron energy-loss spectroscopy (EELS) to examine the distribution and coordination environment of silicon in murine osteoblasts (OBs) in an in vitro model of bone formation. SIMS analysis showed a high level of surface contamination from polydimethysiloxane (PDMS) resulting from sample preparation. When the PDMS was removed, silicon compounds could not be detected within the nodules either by SIMS or by energy dispersive X-ray spectroscopy (EDX) analysis. In comparison, electron energy-loss spectroscopy (EELS) provided a powerful and potentially widely applicable means to define the coordination environment and localisation of silicon in mineralising tissues. We show that trace levels of silicon were only detectable from the mineral deposits located on the collagen and in the peripheral region of mineralised matrix, possibly the newly mineralised regions of the OB nodules. Taken together our results suggest that silicon plays a biological role in bone formation, however, the precise mechanism by which silicon exerts its physicochemical effects remains uncertain. Our analytical results open the door for compelling new sets of EELS experiments that can provide detailed and specific information about the role that silicates play in bone
Bode F, da Silva MA, Smith P, et al., 2013, Hybrid gelation processes in enzymatically gelled gelatin: impact on nanostructure, macroscopic properties and cellular response, Soft Matter, Vol: 9, Pages: 6986-6999, ISSN: 1744-683X
Physical, chemical and hybrid tilapia fish gelatin hydrogels were investigated by small-angle neutron scattering (SANS), molecular dynamic simulations and their biological effect in cell cultures studied; results from the different experimental techniques were then correlated and linked to the rheological properties of the gels (F. Bode et al., Biomacromolecules, 2011, 12, 3741–3752). Hydrogels were obtained by cross-linking with the microbial enzyme transglutaminase (mTGase) under two conditions: above and below gelatin physical gelation temperature (ca. 23 °C). Hydrogels cross-linked at 37 °C, from the sol-state, are referred to as ‘chemical’ gels (C); hydrogels cross-linked at 21 °C, thus with concurrent physical gelation, are referred to as ‘physical-co-chemical’ gels (PC). The SANS data were appropriately described by a combination of a Lorentzian and a power law model. For physical gels, the correlation length (ξ) obtained from the fits decreased linearly with gelatin concentration, from 42 to 26 Å for 3.5 to 10% w/w gelatin, respectively. Independently of gelation temperature, all physical gels at a given concentration showed a similar correlation length ξ (26 ± 2 Å), with no significant difference with the sol-state (23 ± 2 Å). In both C and PC gels, ξ increased with mTGase concentration over the range studied: 40 to 167 Å for 10 and 40 U mTGase per g gelatin in C gels (after 120 min cross-linking) and 40 to 82 Å for 10 and 40 U mTGase per g gelatin for PC gels. ξ reached a plateau at the highest mTGase concentration studied for both types of gels. In addition, kinetic studies on C gels revealed that ξ increased linearly with time in the first two hours and grew faster with increasing mTGase concentration. ξ values in the PC gels were smaller than in the corresponding C gels. Cell proliferation studies showed that
Bertazzo S, Gentleman E, Cloyd KL, et al., 2013, Nano-analytical electron microscopy reveals fundamental insights into human cardiovascular tissue calcification, Nature Materials, Vol: 12, Pages: 576-583, ISSN: 1476-4660
Gentleman E, Stevens MM, Hill RG, et al., 2013, Surface properties and ion release from fluoride-containing bioactive glasses promote osteoblast differentiation and mineralization in vitro, Acta Biomaterialia, Vol: 9, Pages: 5771-5779, ISSN: 1878-7568
Chung S, Gentilini C, Callanan A, et al., 2013, Responsive poly (gamma-glutamic acid) fibres for biomedical applications, JOURNAL OF MATERIALS CHEMISTRY B, Vol: 1, Pages: 1397-1401, ISSN: 2050-750X
Hung A, Mager M, Hembury M, et al., 2013, Amphiphilic amino acids: a key to adsorbing proteins to nanopatterned surfaces?, CHEMICAL SCIENCE, Vol: 4, Pages: 928-937, ISSN: 2041-6520
de Jonge LT, Stevens MM, 2013, Peptide nanotube coatings for bioapplications, Handbook of Biofunctional Surfaces, Pages: 569-590, ISBN: 9789814316637
Pashuck ET, Stevens MM, 2012, Designing Regenerative Biomaterial Therapies for the Clinic, SCIENCE TRANSLATIONAL MEDICINE, Vol: 4, ISSN: 1946-6234
de la Rica R, Stevens MM, 2012, Plasmonic ELISA for the ultrasensitive detection of disease biomarkers with the naked eye, Nature Nanotechnology, Vol: 7, Pages: 821-824, ISSN: 1748-3395
Cloyd KL, El-Hamamsy I, Boonrungsiman S, et al., 2012, Characterization of porcine aortic valvular interstitial cell 'calcified' nodules, PLOS One, Vol: 7, ISSN: 1932-6203
Valve interstitial cells populate aortic valve cusps and have been implicated in aortic valve calcification. Here we investigate a common in vitro model for aortic valve calcification by characterizing nodule formation in porcine aortic valve interstitial cells (PAVICs) cultured in osteogenic (OST) medium supplemented with transforming growth factor beta 1 (TGF-β1). Using a combination of materials science and biological techniques, we investigate the relevance of PAVICs nodules in modeling the mineralised material produced in calcified aortic valve disease. PAVICs were grown in OST medium supplemented with TGF-β1 (OST+TGF-β1) or basal (CTL) medium for up to 21 days. Murine calvarial osteoblasts (MOBs) were grown in OST medium for 28 days as a known mineralizing model for comparison. PAVICs grown in OST+TGF-β1 produced nodular structures staining positive for calcium content; however, micro-Raman spectroscopy allowed live, noninvasive imaging that showed an absence of mineralized material, which was readily identified in nodules formed by MOBs and has been identified in human valves. Gene expression analysis, immunostaining, and transmission electron microscopy imaging revealed that PAVICs grown in OST+TGF-β1 medium produced abundant extracellular matrix via the upregulation of the gene for Type I Collagen. PAVICs, nevertheless, did not appear to further transdifferentiate to osteoblasts. Our results demonstrate that ‘calcified’ nodules formed from PAVICs grown in OST+TGF-β1 medium do not mineralize after 21 days in culture, but rather they express a myofibroblast-like phenotype and produce a collagen-rich extracellular matrix. This study clarifies further the role of PAVICs as a model of calcification of the human aortic valve.
McCullen SD, Autefage H, Callanan A, et al., 2012, Anisotropic Fibrous Scaffolds for Articular Cartilage Regeneration, TISSUE ENGINEERING PART A, Vol: 18, Pages: 2073-2083, ISSN: 1937-3341
Stevens MM, 2012, Keynote: New materials-based strategies for regenerative medicine, JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Vol: 6, Pages: 406-406, ISSN: 1932-6254
Boonrungsiman S, Gentleman E, Carzaniga R, et al., 2012, The role of intracellular calcium phosphate in osteoblast-mediated bone apatite formation, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 109, Pages: 14170-14175, ISSN: 0027-8424
de la Rica R, Aili D, Stevens MM, 2012, Enzyme-responsive nanoparticles for drug release and diagnostics, ADVANCED DRUG DELIVERY REVIEWS, Vol: 64, Pages: 967-978, ISSN: 0169-409X
Bell NC, Minelli C, Tompkins J, et al., 2012, Emerging Techniques for Submicrometer Particle Sizing Applied to Stober Silica, LANGMUIR, Vol: 28, Pages: 10860-10872, ISSN: 0743-7463
Rodriguez-Lorenzo L, de la Rica R, Alvarez-Puebla RA, et al., 2012, Plasmonic nanosensors with inverse sensitivity by means of enzyme-guided crystal growth, Nature Materials, Vol: 11, Pages: 604-607, ISSN: 1476-4660
Evans ND, Swain RJ, Gentleman E, et al., 2012, GENE-EXPRESSION ANALYSIS REVEALS THAT EMBRYONIC STEM CELLS CULTURED UNDER OSTEOGENIC CONDITIONS PRODUCE MINERAL NON-SPECIFICALLY COMPARED TO MARROW STROMAL CELLS OR OSTEOBLASTS, EUROPEAN CELLS & MATERIALS, Vol: 24, Pages: 211-223, ISSN: 1473-2262
Place ES, Nair R, Chia HN, et al., 2012, Latent TGF-beta Hydrogels for Cartilage Tissue Engineering, ADVANCED HEALTHCARE MATERIALS, Vol: 1, Pages: 480-484, ISSN: 2192-2640
Bonzani IC, Campbell JJ, Knight MM, et al., 2012, Dynamic compressive strain influences chondrogenic gene expression in human periosteal cells: A case study, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 11, Pages: 72-81, ISSN: 1751-6161
Gentilini C, Dong Y, May JR, et al., 2012, Functionalized Poly(gamma-Glutamic Acid) Fibrous Scaffolds for Tissue Engineering, ADVANCED HEALTHCARE MATERIALS, Vol: 1, Pages: 308-315, ISSN: 2192-2640
Stevens MM, Mecklenburg G, 2012, Bio-inspired materials for biosensing and tissue engineering, POLYMER INTERNATIONAL, Vol: 61, Pages: 680-685, ISSN: 0959-8103
Bertazzo S, von Erlach T, Goldoni S, et al., 2012, Correlative light-ion microscopy for biological applications, Nanoscale, Vol: 4, Pages: 2851-2854, ISSN: 2040-3372
Bonnell DA, Hafner JH, Hersam MC, et al., 2012, Recycling is not always good: the dangers of self-plagiarism., ACS Nano, Vol: 6, Pages: 1-4
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