Genetic enhancement of skeletal muscles could potentially benefit elite athletes, patients rehabilitating from injury-induced muscle wasting, and elderly people who have diminished mobility due to muscular weakness, Lee Sweeney and coauthors report in a study appearing in the March 2004 issue of the Journal of Applied Physiology. The research debuted at the Annual Meeting of the American Association for the Advancement of Science (AAAS).
Sweeney suggests that exercise and genetic enhancement work together to increase mass and strength in rat muscles. One technique somehow boosts the other.
The authors suggest that muscle-precursor stem cells called "satellite cells" contributed to the higher muscle mass and strength reported in the exercised, genetically enhanced rats. Their findings support the hypothesis that ladder-climbing exercise primed the satellite cells of these rats. The receptive satellite cells expressed IGF-I receptors that made them responsive to increased levels of IGF-I which, in turn, led to increased mass and strength in genetically enhanced and exercised muscle.
The scientists also report that muscles from rats with genetically elevated levels of IGF-I retain more of their muscle mass after they stop exercising than rats without elevated levels of the growth factor.
The scientists injected a recombinant virus that contained an IGF-I rat gene into a hind-leg muscle (the flexor hallucis longus) of rats. The gene increases production of the growth facto
Contact: Monica Amarelo
American Association for the Advancement of Science