Résumé :
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Cell therapy represents a valid tool for tissue replacement, in particular in the contest of muscle dystrophies or structural defects. Satellite cells (SCs) have been frequently used as source of cells for skeletal muscle replacement, because they represent in vivo the pool of myogenic precursors. SCs are located between the basal lamina and the plasma membrane of skeletal myofibers. They offer the possibility of in vitro expansion and autologous transplantation. According to recent studies, they seem to be divided into two subpopulations, one of committed muscle precursors and one of cells with more stem-like properties. This distinction correlates to both a diversity in markers expression and differentiation potential. In this study, for the first time, two subpopulations of SCs obtained from rat flexor digitorum brevis muscle through single fiber selection and disgregation, were distinguished based on both different proliferative and differentiative capacities. Quantitative analyses showed that there is an almost fixed proportion of SCs that possess a great proliferative potential, and that spontaneously give rise to adipocytes in culture. Immunofluorescence and PCR analyses showed that while initially SCs are homogenously positive for early myogenic markers such as Pax7 and Myf5, pluripotent clones lose in culture myogenic markers and form lipid droplets in cytoplasm, becoming adipocytes. These observations could be relevant in muscle regeneration therapies. Selection of satellite cells by their proliferative ability could have implication in their in vivo regeneration potential.
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