Comparison of basic fibroblast growth factor in X-linked dystrophin-deficient myopathies of human, dog and mouse.

Binding of polyclonal antibodies specific for bFGF was examined in tissue sections of myopathic and normal muscles from humans, dogs and mice. The proposal tested was that differences in the amount or distribution of bFGF in muscles of the 3 species, might correlate with the limited muscle regeneration seen in humans and dogs afflicted with x-linked muscular dystrophy, in contrast with the sustained new muscle formation in mdx mice with the homologous myopathy. There was a striking difference between the species in the binding of bFGF antibodies to extracellular matrix, particularly at the periphery of myofibres; binding was pronounced in mouse but weak or absent in human and dog muscle. Binding to muscle nuclei and sarcoplasm was also stronger in mice than in humans and dogs, and in all species was more pronounced in foetal than adult muscle. Increased binding of bFGF antibodies was seen in damaged and regenerating muscle cells in all myopathic specimens where these were present. This was associated with the regenerative process rather than with myopathy, as a similar pattern of bFGF expression was seen in mouse muscle regenerating after experimental crush injury. The higher extracellular staining for bFGF around the periphery of mouse myofibres correlated with the successful muscle regeneration in dystrophic mice. Results suggest that bFGF at the fibre periphery might stimulate a local increase in the numbers of muscle precursor cells which can respond to injury in the mdx mouse.