title: Aging and endothelial progenitor cell telomere length in healthy men.
abstract: BACKGROUND
  Telomere length declines with age in mature endothelial cells and is thought to contribute to endothelial dysfunction and atherogenesis. Bone marrow-derived circulating endothelial progenitor cells (EPCs) are critical to vascular health as they contribute to both reendothelialization and neovascularization. We tested the hypothesis that EPC telomere length decreases with age in healthy adult humans.
  
  
  METHODS
  Peripheral blood samples were collected from 40 healthy, non-obese, sedentary men: 12 young (age 21-34 years), 12 middle-aged (43-55 years) and 16 older (57-68 years). Putative EPCs were isolated from peripheral blood mononuclear cells and telomere length was determined using genomic DNA preparation and Southern hybridization techniques.
  
  
  RESULTS
  EPC telomere length (base pairs) was approximately 20% (p=0.01) lower in the older (8492+523 bp) compared to the middle-aged (10,565+572 bp) and young (10,205+501 bp) men. Of note, there was no difference in EPC telomere length between the middle-aged and young men.
  
  
  CONCLUSIONS
  These results demonstrate that EPC telomere length declines with age in healthy, sedentary men. Interestingly, telomere length was well preserved in the middle-aged compared to young men, suggesting that EPC telomere shortening occurs after the age of 55 years.
authors.affiliation: Department of Integrative Physiology, Integrative Vascular Biology Laboratory, University of Colorado, Boulder, CO, USA.
authors.forename: Erich J
authors.initials: EJ
authors.lastname: Kushner
authors.forename: Gary P
authors.initials: GP
authors.lastname: Van Guilder
authors.forename: Owen J
authors.initials: OJ
authors.lastname: Maceneaney
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Cech
authors.forename: Brian L
authors.initials: BL
authors.lastname: Stauffer
authors.forename: Christopher A
authors.initials: CA
authors.lastname: DeSouza
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013234:Stem Cells / Q000502:physiology*; D016615:Telomere / Q000737:chemistry*; D055815:Young Adult