Comparison between the growth pattern of cell cultures from normal and Duchenne dystrophy muscle

The growth "in vitro" of muscle cells from 12 patients with Duchenne muscular dystrophy (DMD) was compared with that of muscle cells from 20 age-matched controls. In the DMD explants, the lag phase (3 days) was shorter than in controls (6 days). In dissociated cells, plating efficiency (20%) and doubling time (30 h) were identical in DMD and controls. In cultures from three DMD patients, cell clusters were occasionally observed. Myotube morphometry showed significant abnormalities in DMD cultures: the number of myotubes per field was 8.2 +/- 0.8 and 26.7 +/- 0.6 in controls, P less than 0.001; myotube length (151 +/- 20 micron) and diameter (8.2 +/- 0.9 micron) in DMD cultures were half the control values (312 +/- 46 micron and 15.6 +/- 1.2 micron, respectively, P less than 0.001). The number of nuclei per myotube in DMD was one-quarter of that in control muscle (4.0 +/- 0.2 vs 15.8 +/- 2.2, P less than 0.001). It is concluded that DMD cultures show cellular heterogeneity with the presence of fibroblasts and non-fusing myoblasts; furthermore they show delayed myoblast fusion and poor myotube differentiation.