Stem cell therapy in bone repair and regeneration.

Stem cells of various origins, particularly endothelial progenitor cells (EPCs), have potential to enhance bone repair and regeneration. EPCs are resident in the bone marrow and home to ischemic sites to initiate vasculogenesis. Although it was previously believed that only local endothelial cells arrive at ischemic sites, new evidence suggests that EPCs are recruited from the periphery. This finding has a considerable array of therapeutic implications. For example, administered EPCs can localize to sites of osteogenesis where they increase blood vessel formation; this may be useful in enhancing fracture repair.