MACROPHAGES REGULATE PROLIFERATION AND DIFFERENTIATION OF SATELLITE CELLS

We used an in vitro model to investigate whether macrophages stimulate satellite cells proliferation. Satellite cells were obtained by trypt ic digestion of adult muscle. Macrophages were obtained from peritonea l cavity by wash after injection of thyoglycollate broth. Macrophages and satellite cells cocultures showed an increased number of different iated myotubes as compared to control cultures. Moreover, in condition s of myoblast colony growth, the addition of macrophage-conditioned me dium resulted in a greater number of muscle cell colonies, which are r icher in large and differentiated myotubes. The experiments with macro phage-conditioned media suggest that the increased muscle cell prolife ration and differentiation is mediated by soluble factor(s) released b y macrophages. These results demonstrate that besides their scavenger role macrophages play a pivotal role in myoblast proliferation during muscle regeneration. (C) 1994 Academic Press, Inc.