title: Circulating endothelial progenitor cell numbers are not associated with donor organ age or allograft vasculopathy in cardiac transplant recipients.
abstract: BACKGROUND
  Increasing age is associated with reduced numbers of circulating endothelial progenitor cells (EPCs). It is unclear whether this relates to depletion or impairment of bone marrow progenitors, or to deficient mobilization signals from aging tissues. In cardiac transplant patients, one previous study has reported an association between circulating EPCs and the risk of cardiac allograft vasculopathy (CAV). We investigated whether increased donor heart age, a strong risk factor for CAV, was associated with reduced circulating EPC numbers in a group of cardiac transplant recipients matched for factors which influence EPC numbers, but with maximally discordant donor heart ages.
  
  
  METHODS
  We identified 32 patient pairs, matched for factors known to influence EPC numbers, but who had discordant donor heart ages by at least 20 years. EPCs were quantified using flow cytometry for absolute counts of cells expressing all the combinations of CD45, CD34, CD133 and the kinase domain receptor (KDR).
  
  
  RESULTS
  There were no significant differences in the numbers of circulating EPCs between patients with old or young donor heart age. There was no association between the presence of CAV and circulating EPC numbers.
  
  
  CONCLUSIONS
  We suggest that the increased susceptibility to CAV of older donor hearts is not mediated via circulating EPCs. Our results are consistent with the theory that the normal age-related decline in EPC numbers relates to bone marrow aging rather than failure of target tissues to induce EPC mobilization.
authors.affiliation: University of Newcastle, Newcastle Upon Tyne, United Kingdom. H.E.Thomas@ncl.ac.uk
authors.forename: H E
authors.initials: HE
authors.lastname: Thomas
authors.forename: G
authors.initials: G
authors.lastname: Parry
authors.forename: J H
authors.initials: JH
authors.lastname: Dark
authors.forename: H M
authors.initials: HM
authors.lastname: Arthur
authors.forename: B D
authors.initials: BD
authors.lastname: Keavney
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D002452:Cell Count; D015331:Cohort Studies; D004730:Endothelium, Vascular / Q000166:cytology*; D005260:Female; D005434:Flow Cytometry; D016027:Heart Transplantation / Q000706:statistics & numerical data*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D012307:Risk Factors; D014019:Tissue Donors; D014184:Transplantation, Homologous; D014652:Vascular Diseases / Q000453:epidemiology*