Light- and electron-microscopic studies of transplanted human dystrophic muscles to nude mice.

Light-microscopic study of muscles from 8 patients with Duchenne muscular dystrophy (DMD) and 9 control cases transplanted into nude mice showed the formation of cross-striations and peripheral nuclei in regenerating muscle fibers of both DMD and control grafts up to 4 weeks. Quantitative study of the diameter of myotubes and myoblasts in grafted muscles showed that the group mean diameters of DMD myotubes and myoblasts were 13.4 +/- 0.8 (SE) micrometers, 15.6 +/- 0.7 micrometers, 17.1 +/- 0.9 micrometers and 16.2 +/- 1.0 micrometers after 1, 2, 3 and 4 weeks of transplantation, respectively, whereas those of control myotubes and myoblasts were 14.9 +/- 0.6 (SE) micrometers, 19.9 +/- 0.5 micrometers, 21.3 +/- 0.7 micrometers and 20.7 +/- 0.7 micrometers after the same intervals. The group mean diameters of the DMD regenerating myotubes and myoblasts were significantly smaller than those of control myotubes and myoblasts at 2 (P less than 0.001), 3 (P less than 0.005) and 4 (P less than 0.005) weeks after transplantation. Electron-microscopic findings of DMD muscle grafts were morphologically similar to those seen in control muscle grafts at all stages of this experiment.