title: The PDE5 inhibitor sildenafil increases circulating endothelial progenitor cells and CXCR4 expression.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Department of Histology, Microbiology and Medical Biotechnologies, Centre for Male Gamete Cryopreservation, University of Padova, Italy. carlo.foresta@unipd.it
authors.forename: Carlo
authors.initials: C
authors.lastname: Foresta
authors.forename: Luca
authors.initials: L
authors.lastname: De Toni
authors.forename: Antonella
authors.initials: A
authors.lastname: Di Mambro
authors.forename: Andrea
authors.initials: A
authors.lastname: Garolla
authors.forename: Alberto
authors.initials: A
authors.lastname: Ferlin
authors.forename: Daniela
authors.initials: D
authors.lastname: Zuccarello
mesh_terms: D000328:Adult; D004727:Endothelium / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D008297:Male; D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011687:Purines / Q000008:administration & dosage / Q000494:pharmacology; D019718:Receptors, CXCR4 / Q000378:metabolism*; D000068677:Sildenafil Citrate; D013234:Stem Cells / Q000187:drug effects* / Q000378:metabolism*; D013450:Sulfones / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D058986:Phosphodiesterase 5 Inhibitors; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D019718:Receptors, CXCR4; D013450:Sulfones; D000068677:Sildenafil Citrate