Background.

Myoblast transplantation (MT) is a potential approach for gene transfer into skeletal muscle, the efficiency of which depends upon the number of copies of donor genome incorporated into the host tissue. We have developed a system for quantitative studies of MT that measures amounts of donor-derived genome in host muscles and estimates the contributions of donor cell survival and proliferation in vivo.

Methods.

[14 C] thymidine-labeled, male myoblasts were transplanted into female muscles, providing two donor cell markers, Y chromosome and [14 C]. The markers were measured in muscle extracts by slot blotting and scintillation counting, respectively.

Results.

In each extract, the amount of Y chromosome was used to quantify donor-derived genome, whereas the radiolabel provided an estimate of cell survival. Furthermore, the different modes of inheritance of the markers meant that proliferation of surviving donor cells was detected as a change in marker ratio.

Conclusions.

This system provides a method for assessing potential improvements of MT.

Genetic modification of skeletal muscle by myoblast transplantation (MT*) is one possible route for the treatment of primary inherited myopathies and conditions that could be ameliorated by the systemic delivery of nonmuscle proteins from skeletal muscle (1). Considering the aims of MT, it is appropriate that most experiments have been judged by the expression of donor cell-derived proteins. However, such an approach gives little information concerning the efficiency of the transplantation procedure in terms of donor cell survival and proliferation, factors that are likely to have a significant impact on protein production because they determine the number of copies of donor genome present in the host muscle.