Human skeletal muscle satellite cells: aging, oxidative stress and the mitotic clock.

Normal satellite cell cultures, isolated from human skeletal muscle, have a limited proliferative capacity and inevitably reach replicative senescence. In this study, we have focused on the consequences of a single oxidative stress by hydrogen peroxide (H(2)O(2)) on both proliferative capacity and myogenic characteristics. Treatment with 1mM H(2)O(2) for 30 min causes a small decrease in the viability and lifespan while the number of cells which are able to proliferate, decreases dramatically. This premature arrest of the cells in a non-proliferative state was not due to spontaneous differentiation since there was no increase in the number of myogenin positive cells. This stress did not affect the myogenicity of the cells or their ability to differentiate and fuse to form multinucleated myotubes. In addition, the mitotic clock does not seem to be modified by oxidative stress treatment since the rate of telomere shortening was similar in H(2)O(2)-treated and control cells. This could be the consequence of the high level of oxygen consumption with an even higher level of ROS being produced in skeletal muscle than in other tissues which would be counteracted by an increase in the antioxidant defense system.