A possible method of boosting muscle repair, and thus treating muscle wasting conditions - such as the sarcopenia that attends aging: "a lipid signaling molecule called sphingosine-1-phosphate or 'S1P' can trigger an inflammatory response that stimulates the muscle stem cells to proliferate and assist in muscle repair. ... mdx mice, which have a disease similar to Duchenne Muscular Dystrophy, exhibit a deficiency of S1P, [and] boosting their S1P levels improves muscle regeneration ... The ability of muscles to regenerate themselves is attributed to the presence of a form of adult stem cells called 'satellite cells' that are essential for muscle repair. Normally, satellite cells lie quietly at the periphery of the muscle fiber and do not grow, move or become activated. However, after muscle injury, these stem cells 'wake up' through unclear mechanisms and fuse with the injured muscle, stimulating a complicated process that results in the rebuilding of a healthy muscle fiber. S1P is a lipid signaling molecule that controls the movement and proliferation of many human cell types. ... S1P is able to 'wake up' the stem cells at the time of injury. It involves the ability of S1P to activate S1P receptor 2, one of its five cell surface receptors, leading to downstream activation of an inflammatory pathway controlled by a transcription factor called STAT3. [This results] in changes in gene expression that cause the satellite cell to leave its 'sleeping' state and start to proliferate and assist in muscle repair. ... If these findings are also found to be true in humans with Duchenne Muscular Dystrophy, it may be possible to use similar approaches to boost S1P levels in order to improve satellite cell function and muscle regeneration in patients with the disease. Drugs that block S1P metabolism and boost S1P levels are now being tested for the treatment of other human diseases including rheumatoid arthritis. If these studies prove to be relevant in Duchenne patients, it may be possible to use the same drugs to improve muscle regeneration in these patients. Alternatively, new agents that can specifically activate S1P receptor 2 could also be beneficial in recruiting satellite cells and improving muscle regeneration in muscular dystrophy and potentially other diseases of muscle."