The role of basic fibroblast growth factor in skeletal muscle regeneration.

Muscle growth and regeneration is controlled by locally produced growth factors which activate satellite cells and stimulate their proliferation, differentiation and fusion to form mature myotubes. Basic fibroblast growth factor (bFGF) has been previously shown to promote proliferation and inhibit differentiation of myoblasts in vitro. In comparison, the in vivo role of this growth factor is less well documented. In the present investigation on the role of bFGF in muscle regeneration, bFGF mRNA levels were studied in two experimental systems: (1) primary cell cultures derived from rat skeletal muscles, and (2) an in vivo rat muscle injury model. bFGF mRNA was detected in myoblasts just prior to fusion and in myotubes of primary muscle cell cultures. In the non-injured muscle, bFGF mRNA transcripts were detected in myotubes but not satellite cells. In the in vivo muscle injury model bFGF mRNA was observed in myoblasts and in degenerating and regenerated myotubes. The significance of these experimental results in terms of the role played by bFGF in the myogenic program in vivo are discussed.