['To test the hypothesis that B-type natriuretic peptide (BNP) acts as a potent vasculogenic agent by enhancing the number, proliferation, adhesion, and migration of endothelial progenitor cells (EPCs).', 'BNP is a neurohormonal peptide that predicts outcome and used for treatment in chronic heart failure patients. It has been shown to promote angiogenesis in experimental animals. EPCs have been demonstrated to contribute to postnatal angiogenesis and vasculogenesis.', 'The number of EPC colony forming units (CFU) and levels of N-terminal ProBNP were assayed in patients with severe, yet controlled, New York Heart Association (NYHA) II-IV heart failure. The in vitro effects of BNP on early EPC-CFU numbers, proliferation, migration, adhesive, and vascular tube formation capacities were studied using human and murine systems. The effects of in vivo BNP administration on Sca-1/Flk-1 progenitors and on vasculogenesis in the hindlimb ischemia model were then assayed in wild-type mice.', 'A significant correlation was found between circulating N-terminal ProBNP levels and EPC-CFU numbers. We observed a dose-dependent effect of BNP on the numbers of CFU and proliferation capacity of human EPCs as well as on their adhesive, migratory, and tube formation properties, in vitro. Systemic BNP administration to mice led to a significant increase in bone marrow Sca-1/Flk-1 EPCs and improvement in blood flow and capillary density in the ischemic limbs of mice.'] Does b-type natriuretic peptide enhance vasculogenesis by promoting number and functional properties of early endothelial progenitor cells?