MYOGENIC CELL-PROLIFERATION AND DIFFERENTIATION

It is generally thought that growth factors play a major role in regulating proliferation and differentiation of myogenic cells. Cell culture studies indicate that of the known growth factors, the fibroblast growth factors, the transforming growth factor beta, and the insulin-like growth factor families play the most significant roles in this process. The fibroblast growth factors stimulate proliferation and inhibit differentiation of most cultured myogenic cells. Insulin-like growth factors also stimulate proliferation of myogenic cells, but, in contrast to the fibroblast growth factors, the insulin-like growth factors also stimulate differentiation. Transforming growth factor beta inhibits differentiation of cultured myogenic cells. There are conflicting reports as to its effect on proliferation. The combined effects of these growth factors in vivo may play a major role in determining the rate of proliferation and differentiation of muscle tissue.