DIRECT EFFECTS OF CYCLOSPORINE-A AND CYCLOPHOSPHAMIDE ON DIFFERENTIATION OF NORMAL HUMAN MYOBLASTS IN CULTURE

We examined the direct effects of the commonly used immunosuppressive agents cyclosporin A and cyclophosphamide on cultures of clonally deri ved aneural human myoblasts. When applied to cultures in doses reflect ing the therapeutic dose in vivo, both cyclosporin A and cyclophospham ide had dose-related reproducible effects on myoblast fusion: fusion w as enhanced by cyclophosphamide and inhibited by cyclosporin A. These findings indicate that immunosuppressive agents may have effects on mu scle that are independent of their ability to regulate the immune syst em.