Muscle satellite cells

Abstract

Skeletal muscle satellite cells are quiescent mononucleated myogenic cells, located between the sarcolemma and basement membrane of terminally-differentiated muscle fibres. These are normally quiescent in adult muscle, but act as a reserve population of cells, able to proliferate in response to injury and give rise to regenerated muscle and to more satellite cells. The recent discovery of a number of markers expressed by satellite cells has provided evidence that satellite cells, which had long been presumed to be a homogeneous population of muscle stem cells, may not be equivalent. It is possible that a sub-population of satellite cells may be derived from a more primitive stem cell. Satellite cell-derived muscle precursor cells may be used to repair and regenerate damaged or myopathic skeletal muscle, or to act as vectors for gene therapy. Cell facts: (1) Number of cells in body: 2×10⁷ to 3×10⁷ myonuclei/g, 20–25 kg muscle in average man; 2×10⁵ to 10×10⁵ satellite cells/g, i.e. ∼1×10¹⁰ to 2×10¹⁰ satellite cells per person. (2) Main functions: repair and maintenance of skeletal muscle. (3) Turnover rate: close to zero in non-traumatic conditions—high in disease or severe trauma.