Importance of Satellite Cells in Muscle Development

Importance of Satellite Cells in Muscle Development

Satellite cells play an extremely vital role in muscle development. In all animals, the number of muscles and the number of muscle fibers are predetermined before birth. When a baby is born, the number of muscles and muscle fiber does not grow but only matures. Like other types of cells, muscle cells degenerate and get damaged due to everyday life. Satellite cells sole responsibility is to help recruit myonuclei and regenerate damaged muscle cells.

The origin of satellite cells is unclear. Originally, scientists believed that they were derived from somite cells or remnants of fetal myoblasts. More recently, scientists are finding evidence that leads them to believe that the cells have non-somite origin. These scientists believe that other cell types serve as templates and under certain conditions, they differentiate into satellite cells. Due to the difficulty in obtaining satellite cells, research is very difficult and expensive to perform.

Satellite cells are located between the sarcolemma and the basement membrane of muscle. This location allows them to communicate with the mature muscle fiber although they are separate entities. The satellite cells are rested in G0 phase of the cell cycle. This stage of the cycle allows the satellite cells to remain dormant until they are called upon by the damaged muscle fibers. Although the cells are dormant they remain post-mitotic and have the ability to divide unlike mature muscle fibers.

Like myoblasts, satellite cells are predestined to become muscle fibers. Once activated by an environmental signal, the cells begin to multiply and fuse with the adjacent muscle fibers. This process provides growing muscle fiber with added DNA that increases the ability of muscle fibers to create more protein during cellular hypertrophy.

Although the existing muscle fibers are capable of producing proteins, there is a very high demand due to hypertrophy. The satellite cells are used during growth to help meet the demand for protein. It is also estimated that 95% of DNA in muscle fibers actually comes from the satellite cells. Therefore these cells are not only vital for muscle injuries but also for normal growth.

When a muscle fiber experiences trauma, the existing muscle fiber is partially destroyed. The satellite cells move into the area and once activated, begin