Browsing by Author "Krishnan, Lissy K"

Now showing 1 - 3 of 3
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    Effect of matrix composition on differentiation of nestin-positive neural progenitors from circulation into neurons.
    (Journal of neural engineering, 2010)
    The human peripheral blood mononuclear cell has a mixture of progenitor cells with potential to differentiate into a wide range of lineages. The ability of hematopoietic tissue-derived adult stem cells to differentiate into neural progenitor cells offers an alternative to embryonic stem cells as a viable source for cell transplantation therapies to cure neurodegenerative diseases. This approach could lead to the use of autologous progenitors from blood circulation; however, due to the limited numbers available, in vitro cell expansion may be indispensable. In addition, for successful transplantation there is the requirement of a delivery matrix on which cells can survive and differentiate. In this context we carried out this study to identify a suitable biodegradable matrix on which progenitor cells can home, multiply and differentiate. We designed different compositions of the biomimetic matrix containing fibrin, fibronectin, gelatin, growth factors, laminin and hyaluronic acid. The attached cells expressed proliferation markers in initial periods of culture and between days 6 and 9 in culture they differentiated into neurons and/or astrocytes. The differentiation of progenitors into neurons and asterocyte on the composed matrix was established by morphological and immunochemical analysis. Flow cytometric analysis of cells in culture was employed to track development of neurons which expressed an early marker beta-tubulin3 and a terminal marker microtubule-associated protein-2 at a later culture period. In vitro experiments indicate that a highly specific niche consisting of various components of the extracellular matrix, including hyaluronic acid, promote cell homing, survival and differentiation.
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    Effect of passage number and matrix characteristics on differentiation of endothelial cells cultured for tissue engineering.
    (Biomaterials, 2005)
    Cells can sense the physical and chemical properties of artificial materials used as scaffolds for tissue engineering and regulate their behavior. Therefore, biomimetic and biospecific molecules are coated on materials to regulate function of cells on the tissue-engineered product. These bioactive molecules can be attached in a defined spectrum, concentration and spatial distribution in order to control adhesion, growth, viability, differentiation, and function of the cells. When autologous cells are used for tissue engineering, initially limited cells obtained may often need an amplification of cell number by passage in tissue culture before they are seeded on a biomaterial or scaffold. We have conducted this study to understand how the characteristics of bioactive molecule coating might affect proliferation, apoptosis and differentiation when endothelial cell (EC) is serially passaged. Proliferation was assessed by proliferating cell nuclear antigen (PCNA) staining along with counting of cells harvested from confluent monolayer. Apoptosis was assessed by Annexin V staining and differentiation by semi quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for von Willebrand factor (vWF) expression and quantification of its release using enzyme linked immunosorbant assay (ELISA), and thrombogenicity by comparing platelet adhesion to EC monolayer Dacron grafts (DG) with specific protein coating. The results indicate that ECs easily lose its proliferation potential when they are cultured repeatedly on gelatin, turn apoptotic and over express the prothrombotic protein- vWF. Whereas, when it is grown on a matrix composed of fibrin, fibronectin, gelatin and vascular EC growth factor (VEGF), the cells retained their ability to proliferate, remained viable and were relatively less thrombogenic, even when passage number progressed. It is concluded that if ECs are grown on the composite matrix that mimics natural vessel scaffold, the cell number can be amplified without affecting its normal physiological function and may be used to generate effective tissue-engineered cardiovascular constructs.
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    Functional stability of endothelial cells on a novel hybrid scaffold for vascular tissue engineering.
    (Biofabrication, 2010)
    Porous and pliable conduits made of biodegradable polymeric scaffolds offer great potential for the development of blood vessel substitutes but they generally lack signals for cell proliferation, survival and maintenance of a normal phenotype. In this study we have prepared and evaluated porous poly(epsilon-caprolactone) (PCL) integrated with fibrin composite (FC) to get a biomimetic hybrid scaffold (FC PCL) with the biological properties of fibrin, fibronectin (FN), gelatin, growth factors and glycosaminoglycans. Reduced platelet adhesion on a human umbilical vein endothelial cell-seeded hybrid scaffold as compared to bare PCL or FC PCL was observed, which suggests the non-thrombogenic nature of the tissue-engineered scaffold. Analysis of real-time polymerase chain reaction (RT-PCR) after 5 days of endothelial cell (EC) culture on a hybrid scaffold indicated that the prothrombotic von Willebrand factor and plasminogen activator inhibitor (PAI) were quiescent and stable. Meanwhile, dynamic expressions of tissue plasminogen activator (tPA) and endothelial nitric oxide synthase indicated the desired cell phenotype on the scaffold. On the hybrid scaffold, shear stress could induce enhanced nitric oxide release, which implicates vaso-responsiveness of EC grown on the tissue-engineered construct. Significant upregulation of mRNA for extracellular matrix (ECM) proteins, collagen IV and elastin, in EC was detected by RT-PCR after growing them on the hybrid scaffold and FC-coated tissue culture polystyrene (FC TCPS) but not on FN-coated TCPS. The results indicate that the FC PCL hybrid scaffold can accomplish a remodeled ECM and non-thrombogenic EC phenotype, and can be further investigated as a scaffold for cardiovascular tissue engineering.