title: Microarray-based characterization of a colony assay used to investigate endothelial progenitor cells and relevance to endothelial function in humans.
abstract: OBJECTIVE
  An assay proposed to quantify endothelial progenitor cell (EPC) colonies in humans was investigated to determine the phenotype of recovered cells and their relevance to in vivo endothelial function.
  
  
  RESULTS
  Twelve sedentary subjects participating in a worksite wellness program underwent endothelial flow-mediated dilation (FMD) testing of the brachial artery and blood sampling for EPC colony assay. Microarray-based genotypic characterization of colonies showed surface markers consistent with T lymphocyte phenotype, but not with an EPC (CD34, CD133, VEGFR-2) or endothelial (CD146) phenotype. Gene expression patterns more closely matched T lymphocytes (r=0.87) than endothelial cells (r=0.66) in our microarray database. Flow cytometry of colonies confirmed large populations of CD3+CD45+ T cells (>75%) and few CD146+CD45- endothelial cells (<1%). Further, there was no correlation between colony number and the magnitude of FMD (r=-0.1512, P=0.6389). After exercise training, subjects improved FMD, from 6.7+/-2.0 to 8.7+/-1.9% (P=0.0043). Colonies also increased (P=0.0210), but without relation to FMD (r=0.1074, P=0.7396). T lymphocyte phenotype persisted after exercise (r=0.87).
  
  
  CONCLUSIONS
  Cells in a commonly used EPC colony assay have a gene expression and cell surface marker profile consistent with a predominance of T lymphocytes and have an unclear relevance to endothelial function, either before or after exercise training.
authors.affiliation: Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1454, USA.
authors.forename: Aditi
authors.initials: A
authors.lastname: Desai
authors.forename: Alexander
authors.initials: A
authors.lastname: Glaser
authors.forename: Delong
authors.initials: D
authors.lastname: Liu
authors.forename: Nalini
authors.initials: N
authors.lastname: Raghavachari
authors.forename: Arnon
authors.initials: A
authors.lastname: Blum
authors.forename: Gloria
authors.initials: G
authors.lastname: Zalos
authors.forename: Margaret
authors.initials: M
authors.lastname: Lippincott
authors.forename: J Philip
authors.initials: JP
authors.lastname: McCoy
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Munson
authors.forename: Michael A
authors.initials: MA
authors.lastname: Solomon
authors.forename: Robert L
authors.initials: RL
authors.lastname: Danner
authors.forename: Richard O
authors.initials: RO
authors.lastname: Cannon
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000235:genetics; D001916:Brachial Artery / Q000502:physiology; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D015444:Exercise; D006801:Humans; D016130:Immunophenotyping; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D012313:RNA / Q000235:genetics; D013234:Stem Cells / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology; D014158:Transcription, Genetic; D014471:Umbilical Veins / Q000166:cytology / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D012313:RNA