Beneficial effects of transplanting normal limb-bud mesenchyme into dystrophic mouse muscles.

A new technique is being developed to remedy muscle weakness of hereditary myopathies. Mesenchymal cells dissected from limb-buds of day-12 normal mouse embryos were transplanted into the right solei of 20-day-old normal or dystrophic C56BL/6J-dy2J mice. Host and donors were immunocompatible. Unoperated left solei served as controls. Sham control solei receiving similar surgical treatment but no mesenchyme transplant did not differ from contralateral, unoperated solei. Six to seven months postoperatively the test solei (8 normal and 15 dystrophic) exhibited greater cross-sectional area, total fiber number, and twitch and tetanus tensions than their contralateral controls. Test dystrophic solei contained more normal-appearing and less abnormal-appearing fibers than their controls. Their mean fiber resting potential was intermediate between those of normal and dystrophic controls. There is no difference in twitch time course between test and control solei. The results indicate that such transplantation improves the structure and function of the dystrophic muscles.