Contribution of marrow-derived progenitors to vascular and cardiac regeneration.

Adult bone marrow is a rich reservoir of tissue-specific pluripotent stem and progenitor cells. Accumulating evidence suggest that these cells have the potential of contributing to tissue revascularization and cardiac regeneration. Physiological stress results in the release of specific chemokines and cytokines that promote mobilization of stem cells to the peripheral circulation. Incorporation of these mobilized cells contributes to formation of functional vasculature and sets up stage for tissue regeneration. Vascular Endothelial Growth Factor (VEGF) through interaction with its receptors VEGFR2 and VEGFR1 expressed on endothelial and hematopoietic stem cells promote recruitment of these cells into the sites of tissue injury accelerating vascular healing. Similarly, subset of CD34 + marrow derived cells are mobilized and recruited to the ischemic myocardium, differentiating into cardiac and vascular cells, restoring cardiac function. Identification of cellular mediators and tissue specific chemocytokines that facilitate selective recruitment of marrow-derived stem and progenitor cells to specific organs, will open up new avenues to accelerate cardiovascular regeneration and tissue revascularization.