title: Short-term endothelial progenitor cell colonies are composed of monocytes and do not acquire endothelial markers.
abstract: BACKGROUND
  The aim of this study was to identify circulating endothelial progenitor cells (EPC) with colony-forming capacity and compare them with the monocytic-macrophage lineage.
  
  
  METHODS
  Forty-two healthy donors were analyzed. EPC were cultured with VEGF and b-FGF. Sequential studies were performed on days +7 (colonies) +21 and +35. Monocytic cells were cultured using the same conditions as EPC until day +21 or alternatively by adding IGF.
  
  
  RESULTS
  The number of EPC colonies was higher in BM than in mobilized or steady-state PB. Using EPC medium, monocytic cells formed cord-like structures but no colonies. However, colonies grew when IGF was added to the medium. By immunocytochemistry, colonies showed CD45, CD31 and lysozyme but no vWF. Colonies were CD4+, CD13+dim, CD14+, CD15++, CD16-/+dim, CD31+dim, CD33+dim, CD45+, CD105-/+dim, lysozyme+ and VE-cadherin+, and constantly negative for CD34, CD133 and KDR, when flow cytometry was used. The immunophenotype of pre-cultured and cultured monocytes was similar to that described for EPC.
  
  
  CONCLUSIONS
  Our results suggest that the so-called 'EPC' obtained at 7 days of culture belong to the monocyte-macrophage lineage, as they share immunophenotypic and molecular features.
authors.affiliation: Department of Hematology, Hospital Clínico Universitario de Salamanca, Salamanca, Spain.
authors.forename: N
authors.initials: N
authors.lastname: López-Holgado
authors.forename: M
authors.initials: M
authors.lastname: Alberca
authors.forename: F
authors.initials: F
authors.lastname: Sánchez-Guijo
authors.forename: E
authors.initials: E
authors.lastname: Villarón
authors.forename: J
authors.initials: J
authors.lastname: Almeida
authors.forename: A
authors.initials: A
authors.lastname: Martín
authors.forename: A
authors.initials: A
authors.lastname: Armellini
authors.forename: C
authors.initials: C
authors.lastname: García
authors.forename: B
authors.initials: B
authors.lastname: Blanco
authors.forename: I
authors.initials: I
authors.lastname: Sánchez-Abarca
authors.forename: S
authors.initials: S
authors.lastname: Martín
authors.forename: J A
authors.initials: JA
authors.lastname: Pérez-Simón
authors.forename: R
authors.initials: R
authors.lastname: García-Sanz
authors.forename: J F
authors.initials: JF
authors.lastname: San Miguel
authors.forename: M C
authors.initials: MC
authors.lastname: del Cañizo
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D015415:Biomarkers / Q000032:analysis; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009000:Monocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D014841:von Willebrand Factor / Q000032:analysis / Q000235:genetics
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; D042461:Vascular Endothelial Growth Factor A; D014841:von Willebrand Factor; D016222:Fibroblast Growth Factor 2