title: Absence of Correlation between Changes in the Number of Endothelial Progenitor Cell Subsets.
abstract: OBJECTIVE
  Previously, various methodologies were used to enumerate the endothelial progenitor cells (EPCs). We now know that these methodologies enumerate at least three different EPC subsets: circulating angiogenic cells (CACs), colony-forming unit endothelial cells (CFU-ECs), and endothelial colony-forming cells (ECFCs). It is not clear whether there is a correlation between changes in the number of these subsets. The aim of the current study is to find an answer to this question.
  
  
  METHODS
  The number of all EPC subsets was quantified in the peripheral blood of nine pregnant women in their first and third trimesters of pregnancy. We enumerated 14 cell populations by quantitative flow-cytometry using various combinations of the markers, CD34, CD133, CD309, and CD45, to cover most of the reported phenotypes of CACs and ECFCs. Culturing technique was used to enumerate the CFU-ECs. Changes in the number of cells were calculated by subtracting the number of cells in the first trimester peripheral blood from the number of cells in the third trimester peripheral blood, and correlations between these changes were analyzed.
  
  
  RESULTS
  The number of CFU-ECs did not correlate with the number of ECFCs and CACs. Also, CACs and ECFCs showed independent behaviors. However, the number of CACs showed a strong correlation with the number of CD133(+)CD309(+) cells (p=0.001) and a moderate correlation with the number of CD34(+)CD309(+) cells (p=0.042). Also, the number of ECFCs was correlated with the number of CD309(+)CD45(-) cells (p=0.029) and CD34(+)CD45(-) cells (p=0.03).
  
  
  CONCLUSIONS
  Our study showed that the three commonly used methods for quantifying EPC subsets represent different cells with independent behaviors. Also, any study that measured the number of EPCs using the flow cytometry method with a marker combination that lacks CD309 may be inaccurate.
authors.affiliation: Department of Cardiovascular Medicine, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. ; Cell and Molecular Medicine Research Club, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. ; Student Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Armin
authors.initials: A
authors.lastname: Attar
authors.affiliation: Department of Cardiovascular Medicine, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. ; Cardiovascular Research Center, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Kamran
authors.initials: K
authors.lastname: Aghasadeghi
authors.affiliation: Department of OB-GYN, Division of Infertility and Reproductive Medicine, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. ; Infertility and Reproductive Medicine Research Center, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mohammad Ebrahim
authors.initials: ME
authors.lastname: Parsanezhad
authors.affiliation: Perinatology Research Center, Infertility Reaserch Center, Department of OB-GYN, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Bahia
authors.initials: B
authors.lastname: Namavar Jahromi
authors.affiliation: Department of Immunology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Habibagahi
keywords: Endothelial progenitor cells; Endothelium