Effects of nonsteroidal antiinflammatory medication on satellite cell proliferation during muscle regeneration

Previous experimental studies have indicated delayed muscle regeneration after nonsteroidal antiinflammatory drug therapy. Successful regeneration of muscle after injury requires activation of normally dormant satellite cells that share the basal laminae with adjacent muscle cells. In the presence of adequate capillary ingrowth, satellite cells proliferate into myotubes and eventually form new muscle cells. In this study, the onset and extent of satellite cell and fibroblast proliferation as well as the production of myotubes and capillaries were analyzed with immunohistochemical methods after contusion injuries to rats' gastrocnemius muscles. Two groups of animals received daily doses of an intramuscular nonsteroidal antiinflammatory drug (naproxen) starting 6 hours and 3 days after injury, respectively. Treated animals were compared with similarly injured untreated animals. Satellite cell and fibroblast proliferation were unaffected by the treatment, and there were no significant differences in myotube or capillary production between treated and control animals. We conclude that naproxen treatment does not compromise the basic process of myofiber regeneration after injury.