Erythropoietin: a new tool for muscle disorders?

The main action of erythropoietin (EPO) is to regulate the production of red cells. However both experimental evidence and clinical experience suggest that erythropoietin has a positive effect on skeletal and cardiac muscle. Mice lacking EPO or its receptors suffer from hearth hypoplasia and have a reduced number of proliferating cardiac myocytes. EPO receptors are expressed on mouse primary satellite cells and in cultured myoblasts, and their stimulation appears to enhance proliferation and reduce the differentiation of both cell types. Moreover EPO is capable of promoting angiogenesis in muscle cells, which provides an additional route to increase oxygen supply to active muscles. In men, the effects of EPO on muscle cells are suggested by the illegal use of EPO by agonistic and amateur athletes to enhance their performances. In some athletes EPO improved their long-duration muscular performances much more than expected on the basis of the increment of the blood hemoglobin alone. Our proposal is to investigate the effect of EPO treatment in various animal models of muscular dystrophies (MD), which are common hereditary primary muscle disorders characterized by muscle damage and wasting, to date without any effective treatment. The ability of EPO to induce the proliferation of satellite cells in the presence of differentiating conditions, typical of the damaged muscle, may represent a tool to expand the cellular population competent for muscle repair. This would lengthen the period when muscles can be efficiently repaired. In the presence of positive results, the possibility could be considered of selecting some of the human forms of MD and treating the patients with EPO.