Normal growth and regenerating ability of myoblasts from unaffected muscles of facioscapulohumeral muscular dystrophy patients

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disease characterized by a typical regional distribution, featuring composed patterns of clinically affected and unaffected muscles. No treatment is available for this condition, in which the pathophysiological mechanism is still unknown. Autologous transfer of myoblasts from unaffected to affected territories could be considered as a potential strategy to delay or stop muscle degeneration. To evaluate the feasibility of this concept, we explored and compared the growth and differentiation characteristics of myoblasts prepared from phenotypically unaffected muscles of five FSHD patients and 10 control donors. According to a clinically approved procedure, 10(9) cells of a high degree of purity were obtained within 16-23 days. More than 80% of these cells were myoblasts, as demonstrated by labeling of the muscle markers CD56 and desmin. FSHD myoblasts presented a doubling time equivalent to that of control cells; they kept high proliferation ability and did not show early telomere shortening. In vitro, these cells were able to differentiate and to express muscle-specific antigens. In vivo, they participated to muscle structures when injected into immunodeficient mice. These data suggest that myoblasts expanded from unaffected FSHD muscles may be suitable tools in view of autologous cell transplantation clinical trials.