title: Reduction of both number and proliferative activity of human endothelial progenitor cells in obesity.
abstract: OBJECTIVE
  Circulating endothelial progenitor cells (EPCs), responsible for neoangiogenesis and vascular repair, negatively correlate with vascular dysfunction and atherosclerotic risk factors. Because obesity may have a crucial role in the development of endothelial dysfunction, this study evaluated the number and proliferative activity of circulating human EPCs in obese (body mass index (BMI)=48+/-9, n=45) compared with lean (23+/-2, n=45) volunteers.
  
  
  METHODS
  EPCs were quantified after isolation of peripheral blood mononuclear cells (PBMCs) using fluorescence-activated cell sorting analyses. In addition, plated PBMCs developed colony-forming units (CFUs) from which 'outgrowth' endothelial cells (OECs) sprouted and differentiated into mature endothelial cells. Growth rates were monitored by periodical microscopic evaluation. Cell-cycle protein expression was determined by western blot analyses.
  
  
  RESULTS
  BMI negatively correlated (P<0.01) with the number of CD34(+)/CD133(+)/KDR(+) (r=-0.442), CD34(+)/KDR(+) (r=-0.500) and CD133(+)/KDR(+) (r=-0.282) EPCs. Insulin, leptin, HbA(1c), high-sensitivity C-reactive protein and hypertension, as well as diminished high-density lipoprotein and apolipoprotein A1, were not only associated with obesity but also with significantly reduced EPC levels. Applying selective culture conditions, EPC-CFUs differentiated into OECs that proliferated more slowly when derived from obese compared with lean subjects (obese: 19.9+/-2.2% vs lean: 30.9+/-3.2% grown area per week, P<0.01). The reduced proliferation was reflected by decreased (P<0.05, n=24 for each group) expression of cell-cycle-promoting cyclins and E2F-1, by hypophosphorylation of retinoblastoma protein and by increased (P<0.05, n=24 for each group) expression of the cell-cycle inhibitor p21(WAF-1/Cip1).
  
  
  CONCLUSIONS
  Reduced numbers of EPCs along with their premature senescence, as shown in this study, could function as early contributors to the development and progression of vascular dysfunction in obesity.
authors.affiliation: Department of Internal Medicine III, Clinical Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Tobler
authors.forename: A
authors.initials: A
authors.lastname: Freudenthaler
authors.forename: S M
authors.initials: SM
authors.lastname: Baumgartner-Parzer
authors.forename: M
authors.initials: M
authors.lastname: Wolzt
authors.forename: B
authors.initials: B
authors.lastname: Ludvik
authors.forename: E
authors.initials: E
authors.lastname: Nansalmaa
authors.forename: P J
authors.initials: PJ
authors.lastname: Nowotny
authors.forename: D
authors.initials: D
authors.lastname: Seidinger
authors.forename: S
authors.initials: S
authors.lastname: Steiner
authors.forename: A
authors.initials: A
authors.lastname: Luger
authors.forename: M
authors.initials: M
authors.lastname: Artwohl
mesh_terms: D000293:Adolescent; D000328:Adult; D015153:Blotting, Western; D002452:Cell Count; D002454:Cell Differentiation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology* / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D009765:Obesity / Q000473:pathology* / Q000503:physiopathology; D012307:Risk Factors; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D055815:Young Adult