The cellular derivation and the life span of the myofibroblast.

The presence of myofibroblasts in granulation tissue and various fibrotic settings is well established. Recent work on this cell has shown that myofibroblasts derive mainly from local fibroblasts, but also from pericytes and smooth muscle cells as well as from specialized cells such as perisinusoidal stellate cells of the liver and mesangial cells of the kidney glomerulus. During the healing of an open wound, myofibroblasts disappear by means of apoptosis when the wound is closed and granulation tissue gradually transforms into scar tissue. The possibility exists that an altered regulation of this process leads to the development of a hypertrophic scar.