Papers by Keyword: Extracellular Matrix

Abstract: Tissue scaffolds can be designed to mimic the native extracellular matrix (ECM), making them attractive for the development for a range of regenerative medicine applications. The macromolecules present in the ECM are critical for the provision of structural support to surrounding cells and signalling cues for the modulation of diverse processes including cell migration, proliferation and healing activation. Here, conformational and transitional behaviour of the ubiquitous ECM protein, fibronectin (Fn), in the presence of bone tissue regeneration scaffolds and living C2C12 myoblast cells is reported. Spectral monitoring of Fn functionalised high plasmonic resonance responsive gold-edge-coated triangular silver nanoplates (AuTSNP) is used to distinguish between compact and extended fibronectin conformations. Large spectral red shifts of ~20 to ~59 nm indicate Fn unfolding and fibril formation on incubation with C2C12 cells. The label-free nature, excellent sensitivity and straightforward application of the AuTSNP within cellular environments presents them as a powerful new tool to signature protein conformational activity in living cells and monitor essential protein activity for the assisted development of improved tissue scaffolds promoting enhanced tissue repair.

Abstract: Natural sulfated glycosaminoglycans (GAGs) play a crucial role as components of the extracellular matrix (ECM). They participate in the regulation of important cellular functions including cell growth, differentiation and signalling. The generation of artificial ECM mimicking selected functions of the native ECM is a promising approach to improve the biological acceptance of materials which are in direct contact to living tissue. In this context we developed synthesis routes for polysaccharide and GAG derivatives bearing both bioactive sulfate and reactive (meth) acrylate functions of different degrees of substitution within the sugar repeating unit. In addition, we studied the photochemically initiated cross-linking of these biopolymer derivatives to form biodegradable hydrogels usable as coatings for biomaterials or scaffolds in tissue engineering.

Abstract: Proteomics is an efficient high throughput technique developed to identify proteins from a crude extract using sequence homology. Advances in Next Generation Sequencing (NGS) have led to increase knowledge of several non-model species. In the field of calcium carbonate biomineralization, the paucity of available sequences (such as the ones of mollusc shells) is still a bottleneck in most proteomic studies. Indeed, this technique needs proteins databases to find homology. The aim of this study was to perform different data mining approaches in order to identify novel shell proteins. To this end, we disposed of several publicly non-model molluscs databases. Previously identified molluscan shell matrix sequences were used as keyword to query annotated databases. BLAST tools and KASS program (KEGG Automatic Annotation Server) were developed to analyse other non-annotated databases. Our results suggest that the efficiency of these methods depends on the quality of the shared data. Finally, an in-house shell matrix protein database has been generated.

Abstract: Tissue engineering by self-assembly hypothesises that optimal repair and regeneration can be achieved best by using the cells’ inherent ability to create organs with proficiency still unmatched by currently available scaffold fabrication technologies. However, the prolonged culture time required to develop an implantable device jeopardises clinical translation and commercialisation of such techniques. Herein, we report that macromolecular crowding, a biophysical in vitro microenvironment modulator, dramatically accelerates extracellular matrix deposition in cultured human corneal, lung and dermal fibroblasts and human bone marrow mesenchymal stem cells. In fact, an almost 5 to 30 fold increase in collagen type I deposition was recorded as early as 48 hours in culture, without any negative effect in cell phenotype and function.

Abstract: Angiogenesis is the formation of new microvascular network from the pre-existing blood vessel. In tissue engineering approaches, angiogenesis is essential for the promotion of micro-vascular network inside an engineered scaffold construct, mimicking a functional blood vessel in vivo. In the in vivo system, the formation of new blood vessels depends on the properties fibrin gel extracellular matrix. In this study, we have investigated the effect of different fibrinogen and thrombin composition on the biophysical properties of fibrin gel. Higher concentration of thrombin (4.0 Units/milliliter) yields a shorter clotting time of the fibrin gel and result in better water uptake property while at lower concentration of thrombin (0.5 Units/milliliter), the clotting time takes much longer. Also, at lowest concentration ratio of fibrinogen to thrombin (0.5 milligram/milliliter to 4.0 Units/milliliter), the turbidity study shows the lowest absorbance compared to other samples. Different concentration of fibrinogen and thrombin also affect the microstructure of the fibrin gel. The variation of these properties will be then manipulated to be used for in vitro angiogenesis. This study opens broader application of fibrin extracellular matrix in regenerative medicine and tissue engineering researches.

Abstract: Chimeric proteins have been used for years for various purposes ranging from biomaterials to candidate drug molecules, and from bench to bulk. Regenerative medicine needs various kinds of proteins for providing essential factors for maintaining starting cells, like induced pluripotent stem cells (iPSC), and renewal, proliferation, targeted differentiation of these cells, and as extracellular matrix for the experimental cells. However, there are several challenges associated with making functional chimeric proteins for effective application as biomaterial in this field. Fc-chimeric protein technology could be an effective solution to overcome many of them. These tailored proteins are recently becoming superior choice of biomaterials in stem cell technology and regenerative medicine due to their specific advantageous biophysical and biochemical properties over other chimeric forms of same proteins. Recent advances in recombinant protein-related science and technology also expedited the popularity of this kind of engineered protein. Over the last decade our lab has been pioneering this field, and we and others have been successfully applied Fc-chimeric proteins to overcome many critical issues in stem cell technologies targeting regenerative medicine and tissue engineering. Fc-chimeric protein-based biomaterials, specifically, E-cad-Fc have been preferentially applied for coating of cell culture plates for establishing xenogeneic-agent free monolayer stem cell culture and their maintenance, enhanced directed differentiation of stem cells to specific lineages, and non-enzymatic on-site one-step purification of target cells. Here the technology, recent discoveries, and future direction related with the E-cad-Fc-chimeric protein in connection with regenerative medicine are described.

Abstract: The scope of this study was to fabricate and evaluate a novel integrated annulus fibrosus-nucleus pulposus scaffold composed of bone matrix gelatin (BMG) and cartilage extracellular matrix (ECM) respectively. Scaffolds were fabricated by a serial physicochemical and free-drying process. The physiochemical property and compatibility of the composite scaffold with intervertebral disc cells were evaluated. HE staining showed no residual cells in both annulus fibrosus and nucleus pulposus scaffolds. SEM observation revealed that the integration of annulus fibrosus region and nucleus pulposus region was well. The pore diameter of annulus fibrosus scaffold is about 401.4±13.1 μm and the nucleus pulposus scaffold 112.4±21.8 μm, which demonstrated that the composite scaffolds possess interconnected pores structure. The average compressive elastic modulus of the integrated scaffold was 49.06 ±15.57 kpa, which was lower than that of porcine coccyx intervertebral disc, 135.9±28.9 kPa. SEM observation and LIVE/DEAD staining showed good adhesion and high viability of intervertebral disc cells in the integrated scaffold. In conclusion, the integrated annulus fibrosus-nucleus pulposus scaffold can be used for intervertebral disc tissue engineering because of its non-immunogenicity, preservation of ECM composition, good physicochemical property and high biocompatibility with interbertebral disc cells.

Abstract: Although improvements have been made in implant design to increase bone formation and promote successful osseointegration using nanotechnology, the clinical diagnosis of early bone growth surrounding implants remains problematic. The development of a device allowing doctors to monitor the healing cascade and to diagnose potential infection or inflammation is necessary. Biological detection can be examined by the electrochemical analysis of electron transfer (or redox) reactions of extracellular matrix proteins involved in bone deposition and resorption. The use of nanomaterials as signal amplifiers in electrochemical sensors has greatly improved the sensitivity of detection. Nanotechnology-enabled electrochemical sensors that can be placed on the implant surface itself show promise as self-diagnosing devices in situ, possibly to detect new bone growth surrounding the implant and other cellular events to ensure implant success.

Abstract: Osteogenic differentiation of mesenchymal stem cells (MSC) is important in the field of bone tissue engineering. The identification of biological factors that influence osteogenesis is vital for developing a broader understanding of how complex microenvironments play a role in differentiation. The aim of this study was to demonstrate that adipose-derived stem cell (ADSC) osteogenesis is enhanced through interaction with extracellular matrices (ECM) secreted by ADSC undergoing osteogenesis. ADSC were obtained from human patients following elective abdominoplasty. Cells were selected for plastic adherence, characterized, and induced to differentiate using osteogenic supplements (OS; dexamethasone, ascorbic acid, and beta-glycerol phosphate). Cells were removed at several time points during osteogenesis and the secreted ECM was isolated. Undifferentiated cells were re-seeded onto the cell secreted ECMs and induced to differentiate with OS. At several time points, cells cultured on ECMs or tissue culture plastic controls (i.e. uncoated surface) were collected and RNA isolated. QPCR and gene array analysis revealed enrichment of osteogenic markers and more rapid progression through osteogenic maturational phases in cells seeded onto ECM secreted at the midpoint in differentiation (ca. 15 days). Our results demonstrate that the cumulative deposition of ECM reaches a critical point at approximately 15 days, before which there appear to be no definitive osteogenic cues from the matrix, and after which, strong drivers of osteogenesis are present. The creation of microenvironments that contain essential morphogenic matrix signals is an important step towards methods of growing and differentiating MSC in a rapid effective manner, particularly for bone-related clinical applications.

Abstract: There are many research shows that the umbilical cord was a “store house” of stem cells. Human umbilical cord mesenchymal stem cell(HUMSC) was considered to be an idea seed cell for cell therapy and cell models construction used in drug development. But the regulation of HUMSC proliferation and differentiation in vitro is facing challenges. This research aimed to construct a biomimic microenvironment using bioactive materials including the fusion protein of E-cadherin-Fc and promote HUMSC proliferation. The adhersion and proliferation of HUMSC measured by MTT assay, were obviously enhanced on E-cadherin-Fc coated surfaces, comparing with these on the gelatin coated surfaces and conventional conditions. Meanwhile, the expression of CD105 assayed by flow cytometry, showing that the pluripotency of HUMSC cultured on the E-cadherin-Fc coated surfaces were higher than that in the tissue treated plate. From the above, the establishment of E-cadherin-Fc microenvionment is beneficial for HUMSC proliferation in vitro.