In recent years, numerous reports have identified in mouse different sources of myogenic cells distinct from satellite cells that exhibited a variable myogenic potential in vivo. Myogenic stem cells have also been described in humans, although their regenerative potential has rarely been quantified. In this study, we have investigated the myogenic potential of human muscle–derived cells based on the expression of the stem cell marker CD133 as compared to bona fide satellite cells already used in clinical trials. The efficiency of these cells to participate in muscle regeneration and contribute to the renewal of the satellite cell pool, when injected intramuscularly, has been evaluated in the Rag2−/− γC−/− C5−/− mouse in which muscle degeneration is induced by cryoinjury. We demonstrate that human muscle–derived CD133+ cells showed a much greater regenerative capacity when compared to human myoblasts. The number of fibers expressing human proteins and the number of human cells in a satellite cell position are all dramatically increased when compared to those observed after injection of human myoblasts. In addition, CD133+/CD34+ cells exhibited a better dispersion in the host muscle when compared to human myoblasts. We propose that muscle-derived CD133+ cells could be an attractive candidate for cellular therapy.2030-01-01