After age thirty, the mass of our muscles decreases by about three to eight percent every decade. The rate of loss gets worse after age sixty. This loss of muscle mass, strength, and function is part of the aging process and contributes to disability in older people. Muscle loss can also be caused by injury.
In 2021 a team of researchers based in the United States and Spain published new research that may be a step towards preventing muscle deterioration, and restoring lost or injured muscle tissue. The researchers successfully triggered the regeneration of muscle cells in mice using a set of proteins called the Yamanaka factors. Named for the Japanese biochemist whose Nobel prize-winning research discovered them, these proteins control how the information in DNA is expressed to make other proteins.
The Yamanaka factors first caught the interest of molecular biologists when they discovered that they can cause adult cells to turn back into pluripotent stem cells like those found in embryos. Later, researchers found that, when supplied in more limited doses, the Yamanaka factors can rejuvenate cells without causing them to return to a pluripotent state and can promote tissue regeneration in live animals. In the mice, the researchers found that these proteins cause muscles to regenerate by activating muscle stem cells, called satellite cells. Satellite cells can augment existing muscle fibers, or develop into new ones.The researchers found evidence that the Yamanaka factors do this work by reducing the expression of a particular protein. The researchers hope that their experiments lead to a better understanding of how the Yamanaka factors work, and, eventually, to treatments that can restore muscle mass, strength, and function in humans.