Mesenchymal stem cells and musculoskeletal repair

The biological signals at the site of injury allow mesenchymal progenitor cells to migrate, proliferate, and differentiate into appropriate repair tissues. These cells are ubiquitously present throughout the body, and they can differentiate to osteoblast, chondrocyte, fibroblast, and adipocytes under appropriate conditions. Failure of repair may be due to an inadequate progenitor cell response to the injury. The current approaches of optimizing repair of damaged tissue use strategies to influence progenitor cells during the repair process. These strategies include direct delivery of progenitor cells or delivery of factors to influence locally present progenitor cells. Direct delivery of progenitor cells, as in autologous bone grafting, is a clinically proven method of inducing osteogenesis. Current research focuses on delivering culturally expanded progenitor cells, using such cytokines as BMPs to facilitate differentiation of progenitor cells to appropriate cell types, and using genetically modified progenitor cells to deliver both cells and factors to the repair site. (C) 2000 Lippincott Williams and Wilkins, Inc.