Satellite Cells Contribution to Exercise Mediated Muscle Hypertrophy and Repair

Abstract

Satellite cells (SCs) are the most abundant skeletal muscle stem cells. They are widely recognized for their contributions to maintenance of muscle mass, regeneration and hypertrophy during the human life span. These cells are good candidates for cell therapy due to their self-renewal capabilities and presence in an undifferentiated form. Presently, a significant gap exists between our knowledge of SCs behavior and their application as a means for human skeletal muscle tissue repair and regeneration. Both physiological and pathological stimuli potentially affect SCs activation, proliferation, and terminal differentiation the former category being the focus of this article. Activation of SCs occurs following exercise, post-training micro-injuries, and electrical stimulation. Exercise, as a potent and natural stimulus, is at the center of numerous studies on SC activation and relevant fields. According to research, different exercise modalities end with various effects. This review article attempts to picture the state of the art of the SCs life span and their engagement in muscle regeneration and hypertrophy in exercise.

Keywords: Exercise; Plasticity; Resistance Training; Skeletal Muscle Satellite Cells.

Fig.1

The morphological and functional changes of satellite cells (SCs) in response to exercise. Resistance and endurance exercise via endo-, para-, or autocrine mechanisms activate SC from a quiescent state where they undergo proliferation, commitment, and differentiation to add myonuclei to preexisting myofibrils or self-renew, and return to the quiescent state. During early stages of myogenic linage PAX7, CD56, and Myf5 derive the activation and proliferation process, however at later stages MRF4 and myogenin have a master regulatory role by controlling terminal differentiation (green color).