Myoblast transplantation: the current status of a potential therapeutic tool for myopathies.

The implantation of cultured myogenic cells into the body (myoblast transplantation) is an experimental strategy that is being explored for the potential treatment of myopathies. Its potential benefits should be: (1) to slow down or to stop muscle degeneration, and/or (2) to increase force in wasted muscles. For these objectives, myoblast transplantation may act by two actions: (1) genetic complementation (as a vehicle of normal genes in the case of genetic myopathies), and (2) increasing the myogenic pool of the muscle. During the last decade, myoblast transplantation seemed stagnant in a contradiction of experiments producing good results in mice, against the poor results of human trials. This contradiction was apparent, since the conditions used in mouse models were largely different from those used in dystrophic patients. Our monkey experiments demonstrated that promising results can be observed in large muscles of primates, but under conditions that differ from those previously used in patients. These conditions are: (1) an appropriate immunosuppression, and (2) a careful distribution of sufficient quantities of myoblasts into the recipient muscles. Most of the work on myoblast transplantation is addressed to improve this method by: (1) reducing or avoiding the toxicity of sustained immunosuppression, (2) favoring donor-myoblast migration into the recipient muscle, and (3) defining the factors implicated in the early donor-cell survival following intramuscular implantation. Other research subjects in this field are the potential use of pluripotent stem cells instead of satellite cells, and the potential delivery of the exogenous myogenic cells by the blood stream.