Abnormality of cultured muscle and Schwann's cells in familial lipid neuromyopathy. Muscle corrected by neural influence
V. Askanas, W. K. Engel, H. H. Kwan and J. V. Lawrence
Muscle and Schwann's cell cultures were established from a family (mother
and two sons) with non-carnitine deficient neuromyopathy. Electron
microscopy of noninnervated cultured muscle showed poorly matured muscle
fibers containing large "mushy" mitochondria, lipid droplets, abundant
multilaminated inclusions, and dense-core dark osmiophilic bodies. Parallel
innervated muscle fibers (cocultured with normal-rat motor neurons for two
to three weeks) were well cross-striated, had well-developed T tubules and
sarcoplasmic reticulum, and none of the abnormalities of aneural muscle
cultures. Cultured Schwann's cells were normal by light microscopy, but had
ultrastructurally abnormal mitochondria, lipid droplets, dark osmiophilic
granular inclusions, and numerous "foamy" vacuoles. Those studies
demonstrated (1) intrinsic muscle and Schwann's cell defects because of
reproduction of abnormalities in culture, (2) normal muscle cell
responsiveness to innervation reflected by development of contractions and
longer survival in culture, and (3) beneficial influence of a neural
factor(s) on the endogenous muscle cell abnormality.