Organ damage and the resultant inflammatory responses initiate a series of repair processes, including stem cell proliferation, migration, and differentiation, often in combination with angiogenesis and remodeling of the extracellular matrix. Endogenous stem cells in tissues such as liver and skin have a remarkable ability to regenerate the organs, whereas heart and brain have a much more limited capability for self-repair. Under rare circumstances, circulating stem cells may contribute to regenerative responses by migrating into a tissue and differentiating into organ-specific cell types. .
