Myosatellite Cells under Gravitational Unloading Conditions

Skeletal muscles are well known to have a high degree of plasticity. Gravitational unloading has a strong impact on the structural and functional organization of the postural muscles. Skeletal muscle has a unique ability to repair damage. Recovery (regeneration) of muscles is carried out by satellite cells. Myosatellite cells are quiescent mononuclear cells (G0 cell cycle phase) located at the periphery of the muscle fiber. When muscles are damaged, satellite cells are activated and become involved in proliferation, giving rise to new satellite cells and myoblasts. Differentiated myoblasts can fuse with muscle fibers during muscle hypertrophy and regeneration, as well as with each other to form new muscle fibers. Studies of the effect of gravitational unloading on muscle satellite cells are scarce. This review addresses the influence of gravitational unloading on the pool of muscle satellite cells and the mechanisms of skeletal muscle regeneration after injury. Based on the literature data, the authors found out that the mechanisms underlying a change in the regenerative potential of muscles under gravitational unloading conditions are poorly understood. The authors highlight the need for further studies of the regenerative potential of satellite cells under microgravity conditions.