Satellite cells are found in the mature muscle around the muscle fibres, and differentiate from myoblasts. These cells are involved in the normal growth of muscle, as well as regeneration following injury or disease. Satellite cells are adult stem cells specific to skeletal muscle fibers, and are also known as skeletal muscle myoblasts.

When muscle cells undergo insult or injury, these cells are released from beneath the basal lamina. While normally in a post-mitotic state, they re-enter the cell cycle and clone themselves. These clones aggregate, again become post-mitotic, and form a myotube. This myotube differentiates into normal, complex muscle tissue, thus repairing the injured site.

Research is currently underway to investigate whether satellite cells can differentiate into viable cardiac muscle cells. Normal cardiac cells are unable to regenerate, which makes the cardiac muscle death of myocardial infarctions irreversible.

It is known that satellite cells are regulated by a protein called myostatin. Increased levels of myostatin up-regulate a cyclin-dependent kinase inhibitor called p21 and thereby prevent the differentiation of satellite cells.

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Myoblasts | cell biology