390 results found
da Silva MA, Bode F, Drake AF, et al., 2014, Enzymatically cross-linked gelatin/chitosan hydrogels: tuning gel properties and cellular response, Macromolecular Bioscience, Vol: 14, Pages: 817-830, ISSN: 1616-5187
This work investigates the effect of combining physical and chemical gelation processes in a biopolymer blend: chitosan and tilapia fish gelatin. Chemical (C) gels are obtained by cross-linking with the microbial enzyme transglutaminase at 37 °C. Hybrid physical-co-chemical (PC) gels are cross-linked at 21 °C, below gelatin gelation temperature. These protocols provide two microenvironments for the gelation process: in C gels, both gelatin and chitosan are present as single strands; in PC gels, cross-linking proceeds within a transient physical gel of gelatin, filled by chitosan strands. The chitosan/gelatin chemical networks generated in PC gels show a consistently higher shear modulus than pure C gels; they are also less turbid than their C gels counterparts, suggesting a more homogeneous network. Finally, chitosan enhances the gels' shear modulus in all gels. Proliferation assays show that MC3T3 cells proliferate in these mixed, hybrid gels and better so on PC gels than in C mixed gels
Amin HD, Brady MA, St-Pierre J-P, et al., 2014, Stimulation of chondrogenic differentiation of adult human bone marrow-derived stromal cells by a moderate-strength static magnetic field, Tissue Engineering: Parts A, B, and C, Vol: 20, Pages: 1612-1620, ISSN: 1937-3368
Tissue-engineering strategies for the treatment of osteoarthritis would benefit from the ability to induce chondrogenesis in precursor cells. One such cell source is bone marrow-derived stromal cells (BMSCs). Here, we examined the effects of moderate-strength static magnetic fields (SMFs) on chondrogenic differentiation in human BMSCs in vitro. Cells were cultured in pellet form and exposed to several strengths of SMFs for various durations. mRNA transcript levels of the early chondrogenic transcription factor SOX9 and the late marker genes ACAN and COL2A1 were determined by reverse transcription–polymerase chain reaction, and production of the cartilage-specific macromolecules sGAG, collage type 2 (Col2), and proteoglycans was determined both biochemically and histologically. The role of the transforming growth factor (TGF)-β signaling pathway was also examined. Results showed that a 0.4 T magnetic field applied for 14 days elicited a strong chondrogenic differentiation response in cultured BMSCs, so long as TGF-β3 was also present, that is, a synergistic response of a SMF and TGF-β3 on BMSC chondrogenic differentiation was observed. Further, SMF alone caused TGF-β secretion in culture, and the effects of SMF could be abrogated by the TGF-β receptor blocker SB-431542. These data show that moderate-strength magnetic fields can induce chondrogenesis in BMSCs through a TGF-β-dependent pathway. This finding has potentially important applications in cartilage tissue-engineering strategies.
Harrison RH, St-Pierre J-P, Stevens MM, 2014, Tissue Engineering and Regenerative Medicine: A Year in Review, Tissue Engineering Part B-Reviews, Vol: 20, Pages: 1-16, ISSN: 1937-3376
May JR, Gentilini C, Clarke DE, et al., 2014, Tailoring of mechanical properties of derivatized natural polyamino acids through esterification and tensile deformation, RSC ADVANCES, Vol: 4, Pages: 2096-2102
Tsigkou O, Labbaf S, Stevens MM, et al., 2014, Monodispersed Bioactive Glass Submicron Particles and Their Effect on Bone Marrow and Adipose Tissue-Derived Stem Cells, ADVANCED HEALTHCARE MATERIALS, Vol: 3, Pages: 115-125, ISSN: 2192-2640
Howes PD, Rana S, Stevens MM, 2013, Plasmonic nanomaterials for biodiagnostics, Chemical Society Reviews, Vol: 43, Pages: 3835-3853, ISSN: 0306-0012
The application of nanomaterials to detect disease biomarkers is giving rise to ultrasensitive assays, with scientists exploiting the many advantageous physical and chemical properties of nanomaterials. The fundamental basis of such work is to link unique phenomena that arise at the nanoscale to the presence of a specific analyte biomolecule, and to modulate the intensity of such phenomena in a ratiometric fashion, in direct proportion with analyte concentration. Precise engineering of nanomaterial surfaces is of utmost importance here, as the interface between the material and the biological environment is where the key interactions occur. In this tutorial review, we discuss the use of plasmonic nanomaterials in the development of biodiagnostic tools for the detection of a large variety of biomolecular analytes, and how their plasmonic properties give rise to tunable optical characteristics and surface enhanced Raman signals. We put particular focus on studies that have explored the efficacy of the systems using physiological samples in an effort to highlight the clinical potential of such assays.
Poh PSP, Hutmacher DW, Stevens MM, et al., 2013, Fabrication and in vitro characterization of bioactive glass composite scaffolds for bone regeneration, BIOFABRICATION, Vol: 5, ISSN: 1758-5082
LaPointe VLS, Fernandes AT, Bell NC, et al., 2013, Nanoscale Topography and Chemistry Affect Embryonic Stem Cell Self-Renewal and Early Differentiation, ADVANCED HEALTHCARE MATERIALS, Vol: 2, Pages: 1644-1650, ISSN: 2192-2640
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 the gels were compatible with cell growth
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
de Jonge LT, Stevens MM, 2013, Peptide nanotube coatings for bioapplications, Handbook of Biofunctional Surfaces, Pages: 569-590, ISBN: 9789814316637
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
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
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.