Résumé :
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Communication n° 611. In skeletal muscle, tissue growth and regeneration need the recruitment of the well-known satellite cells. These resident mononuclear cells constitute a sub-population of the Muscle-Derived Cells (MDCs), which also contain recently described cells with stem cells properties: the Muscular-Derived Stem Cells (MDSCs). In mouse, MDSCs could be isolated by a delayed adhesion to a substrate and then were named Long Term Proliferating cells. These cells, that exhibit a high self-renewal capacities and multipotential abilities, have been shown to improve cell transplantation in mdx mouse. Here, we examined the canine and avian MDCs features in terms of adhesion, to select and characterize the Late Adherent Cells (LACs). MDCs were extracted from hind-limb muscles of 4-week-old dogs and 1-week-old turkeys. Using the preplate technique previously described in mouse and rat, MDCs were separated based on their ability to adhere. LACs, that were isolated after 4 days of process, were plated in primary and clonal cultures to asses 11 days later their myogenic differentiation and proliferation rate. LACs represented 4.0% of the whole canine MDCs and 2.0% of the whole avian ones. In primary culture, dog and turkey LACs remained quiescent, mononucleated and formed sphere-like colonies during the first week. The diameter of these spheres gradually increased until the LACs displayed a fusiform shape and finally fused to form myotubes after 10 days of culture (vs. only 4 days for Early Adherent Cells (EACs)). Also, the delay of differentiation was more than 6 days for the LACs compared to EACs. In clonal culture, the LAC colonies exhibited a poor proliferation rate: 55% of the colonies possessed less than 100 nuclei at day 11 vs. 41% for colonies obtained from EACs. Multipotential abilities assessment and phenotypic characterization of LACs are in progress. The existence of LAC sub-population and its proportion appear similar in dog and in turkey, as in mouse. As this sub-population seems to be a candidate for cell grafting, we need to test it in muscular dystrophy context, as in Golden Retriever Muscular Dystrophy (GRMD) dogs, that represent the most clinically relevant animal model for Duchenne Muscular Dystrophy.
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