Myoblast transplantation.

Myoblast transplantation was the first quasi-gene therapy to be suggested for Duchenne muscular dystrophy. Animal experiments established the principles that the missing gene could be targeted to muscle by grafting of genetically normal myoblasts that were able to repair the disease-damaged muscle fibres. In the recipient muscle the gene was expressed and the resultant protein provided some functional benefit in protecting the fibres against necrosis. However, these effects were limited to a small region around the injection site and there was some evidence of immunological problems. Human trials provided little evidence of effectiveness probably, in part due to immune rejection, and in part to the inadequacy of the cells implanted. Most work since this time has been directed at preventing immune rejection, improving dispersion of the injected cells, and selecting more 'stem cell-like' myogenic cells which might be more effective at reconstituting large regions of muscle. Most recently, a number of sources of 'stem cell' with myogenic potential have been described, some of which have been found to be dispersed via the blood vascular system but none of which have been very efficient at generating new muscle.