Introduction. Endothelial progenitor cells (EPC) are a specific subtype of progenitor cells that can be isolated from circulating mononuclear cells, able to migrate from the bone marrow to the peripheral circulation where they contribute to vascular repair. CXC-motif chemochine receptor 4 (CXCR4) receptor seems to play a critical role in this process.
Aim. To assess the effects of sildenafil (a type 5 phosphodiesterase [PDE5] inhibitor) administration in 20 healthy young men.
Methods. Evaluation of CXCR4 expression in circulating EPC before and 4 hours after in vivo administration of 100 mg sildenafil by flow cytometry and colony-forming unit.
Results. We found that sildenafil increases circulating EPC number, the relative expression of CXCR4 on these cells and the ability to generate colonies in vitro.
Conclusions. These data allow us to suppose an involvement of PDE5 in bone marrow release and peripheral homing of EPC. Foresta C, De Toni L, Di Mambro A, Garolla A, Ferlin A, and Zuccarello D. The PDE5 inhibitor sildenafil increases circulating endothelial progenitor cells and CXCR4 expression. J Sex Med 2009;6:369–372.