Résumé :
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The use of stem cells in regenerative medicine and cell-based therapies offers immense potential in diseases witch have currently no treatment such as Duchenne muscular dystrophy. A limitation to the use of CD133+ for a therapeutic application is the relatively low number of cells that can be recovered from peripheral blood mononuclear cells. The goal of ex vivo expansion is to induce proliferation of blood derived (circulating) CD133+ cells while maintaining their primary functional characteristic. In this work we explored an alternative methods for the expansion of blood-derived stem cells we investigated the interactions between CD133+ cells and smooth surfaces of titanium (TiO2). Our results indicate that cluster-assembled nanostructured TiO2 is biocompatible surface for cell culturing directly supporting normal growth and proliferation of hematopoietic stem cells. In these experiments we also identified a cocktail of cytokines SCF, bFGF, EGF, VEGF, LIF, TEPA, IL6 witch supported the growth of blood CD133+ stem cells. In this condition the cells can be expanded for more than 50 and we observed no indication of replicative senescence or significant changes in cellular division time. The proliferating cells still had the capacity to form hematopoietic and endothelial colonies in semisolid media and differentiate into myogenic cells. Human circulating CD133+ cells were also cultured at 5-percent or 20-percent oxygen in liquid culture in presence of the better cocktail of cytokines and we analysed and compared their expansion capacity and their vitality. The total number of cells increased 6-fold at 5-percent oxygen and could result in a better maintenance of the balance between primitive progenitor cell renewal and clonogenic progenitor expansion, thus representing a tool of remarkable therapeutic interest.
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