Aspects of normal and dystrophic chicken muscle grown in vitro

Tissue culture studies of muscle disorders: Part 2. Biochemical studies, nerve-muscle culture, metabolic myopathies, and animal models

This review continues with studies of protein, lipid, and purine metabolism of Duchenne muscular dystrophy (DMD) cells in vitro and of muscle cells in combined culture with nerve cells. In vitro studies of human metabolic myopathies are tabulated. Results using the hamster, chicken, and mouse (dy25, dy, mdg, and mdx) myopathies are discussed. Interesting findings include suggestions of altered collagen synthesis by DMD cells. Analysis of cell proteins by two-dimensional gel electrophoresis and the use of combined nerve-muscle cultures remain important areas of development. It is disappointing that so few attempts have been made to repeat significant findings in this field, and when a number of laboratories have examined the same phenomenon, the results are often contradictory. It remains to be shown how these various abnormalities found in cells in vitro are related to each other and to those pathologic features of diseased muscle observed in vivo.

The musculus complexus of normal and dystrophic chicken embryos

Abnormalities have previously been reported in the pectoral muscle of embryos and young chicks from a pure strain of New Hampshire Red chickens homozygous for inherited muscular dystrophy. Fine structural studies of the musculus complexus in normal and dystrophic embryos were undertaken because of a sharp decrease in hatching by the diseased birds. Ultrastructural differences found between the normal and dystrophic embryos included a leached sarcoplasm, swollen and distorted mitochondria and tubular components, a lack of polyribosomes (myosin synthesis), and the formation of pseudostraps during differentiation of the myopathic hatching muscle. These differences may curtail differentiation until a point after the critical hatching time.

Precocious in vitro development of satellite cells from dystrophic chicken muscle

Satellite cells, liberated from pectoral muscle of juvenile dystrophic chickens by sequential treatment with collagenase, hyaluronidase, and trypsin and preplated to remove fibroblasts and cultured on gelatin proliferated rapidly, fused and formed confluent muscle cultures within 6 d in vitro with minimal contamination by fibroblasts. When identical isolation and culturing techniques were applied to muscle from age-matched normal chickens proliferation and differentiation were slower, contamination with fibroblasts was much greater, and only a small number of myotubes were formed. After injection of the myotoxic anesthetic marcaine into normal pectoral muscle for 5 consecutive days, myotube formation was accelerated in satellite cell cultures, but the rate of differentiation was not as rapid as that occurring in cells from dystrophic muscle.