Résumé :
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Stem cells with the ability to differentiate in specialized cell types can be extracted from a wide array of adult tissues including skeletal muscle. Here we have characterized a population of stem cells from skeletal muscle that can be reproducibly isolated and grown as a non-adherent, floating population. These cells express the stem cell surface markers Sca-1 and Bcrp-1. Although capable of growing as non-attached spheres for months, when given an appropriate matrix, these cells adhere and give rise to skeletal muscle, neurons and beating cardiac myocytes. Interestingly no similar cell population could be isolated from either bone marrow or cardiac tissue suggesting their specificity to skeletal muscle. When injected into damaged muscle, these muscle-derived floating stem cells are retrieved expressing Pax7, in a sublaminar position characterizing satellite cells and participate in forming new myofibers. These data show that a non adherent-stem cell population can be specifically isolated and expanded from skeletal muscle and this population spontaneously differentiates into muscle, cardiac and neuronal lineages in vitro and contributes significantly to the repair of injured muscle in vivo. These findings support the potential use of a similar muscle derived non-adherent cell population from human muscle in the treatment of neuromuscular disorders. (Key words: muscle; stem cells; multi-lineage differentiation: tissue regeneration )
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