title: Influence of menstrual cycle on circulating endothelial progenitor cells.
abstract: BACKGROUND
  Endothelial progenitor cells (EPCs) are circulating mononuclear cells that participate in angiogenesis. The aim of this study was to determine the influence of the menstrual cycle on the number and function of EPCs, and to investigate their relationship with circulating concentrations of sex steroids and inflammatory mediators.
  
  
  METHODS
  Ten healthy nulliparous, premenopausal, non-smoking women with regular menses were studied over a single menstrual cycle. Venepuncture was performed in the menstrual, follicular, peri-ovulatory and luteal phases. EPCs were quantified by flow cytometry (CD133(+)CD34(+)KDR(+) phenotype) and the colony-forming unit (CFU-EPC) functional assay. Circulating concentrations of estradiol, progesterone and inflammatory mediators (TNF-alpha, IL-6, sICAM-1 and VEGF) were measured by immunoassays.
  
  
  RESULTS
  The numbers of CD133(+)CD34(+)KDR(+) cells were higher in the follicular phase (0.99 +/- 0.3 x 10(6) cells/l) compared with the peri-ovulatory phase (0.29 +/- 0.1 x 10(6) cells/l; P < 0.05). In contrast, the numbers of CFU-EPCs did not vary over the menstrual cycle. There were no correlations between EPCs and concentrations of either circulating sex steroids or inflammatory mediators.
  
  
  CONCLUSIONS
  CD133(+)CD34(+)KDR(+) cells but not CFU-EPCs vary during the menstrual cycle. Our findings suggest a potential role for circulating EPCs in the normal cycle of physiological angiogenesis and repair of the uterine endometrium that is independent of circulating sex steroids or inflammatory mediators.
authors.affiliation: Centre for Reproductive Biology, University of Edinburgh, Edinburgh EH16 4TJ, UK.
authors.forename: A O
authors.initials: AO
authors.lastname: Robb
authors.forename: N L
authors.initials: NL
authors.lastname: Mills
authors.forename: I B J
authors.initials: IB
authors.lastname: Smith
authors.forename: A
authors.initials: A
authors.lastname: Short
authors.forename: O
authors.initials: O
authors.lastname: Tura-Ceide
authors.forename: G R
authors.initials: GR
authors.lastname: Barclay
authors.forename: A
authors.initials: A
authors.lastname: Blomberg
authors.forename: H O D
authors.initials: HO
authors.lastname: Critchley
authors.forename: D E
authors.initials: DE
authors.lastname: Newby
authors.forename: F C
authors.initials: FC
authors.lastname: Denison
mesh_terms: D000071916:AC133 Antigen; D000328:Adult; D015703:Antigens, CD / Q000096:biosynthesis; D018952:Antigens, CD34 / Q000096:biosynthesis; D042783:Endothelial Cells / Q000166:cytology / Q000473:pathology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000473:pathology*; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006023:Glycoproteins / Q000096:biosynthesis; D006801:Humans; D016130:Immunophenotyping; D008597:Menstrual Cycle; D009389:Neovascularization, Pathologic; D010455:Peptides; D013234:Stem Cells / Q000166:cytology*; D013256:Steroids / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000096:biosynthesis
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D018952:Antigens, CD34; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D013256:Steroids; D040301:Vascular Endothelial Growth Factor Receptor-2