title: Osteogenic differentiation of late-outgrowth CD45-negative endothelial progenitor cells.
abstract: OBJECTIVE
  Late-outgrowth CD45-negative endothelial colony-forming cells are implicated to be circulating endothelial progenitor cells (EPCs), as they express endothelial cell markers and can directly form blood vessels. As these cells share characteristics of other progenitor cell phenotypes, late-outgrowth EPCs were assayed for both multilineage differentiation capability and for markers of pluripotency.
  
  
  METHODS
  Clonal single-colony late-outgrowth EPCs were derived from human cord blood and assayed both for multilineage differentiation capability in vitro and for markers of pluripotency by qPCR.
  
  
  RESULTS
  Under osteogenic growth conditions, these EPCs expressed the osteogenic markers RUNX2, COL1A1, ALPL, and osteocalcin and demonstrated calcium deposition and bone mineralization. Endothelial colony-forming cells expressed markers associated with induced pluripotent stem cells, including SOX2, POU5F1, c-MYC, and KLF4.
  
  
  CONCLUSIONS
  Late-outgrowth EPCs express markers associated with pluripotency and can directly express an osteogenic phenotype under bone differentiation conditions in vitro.
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Han
authors.forename: Fred H
authors.initials: FH
authors.lastname: Hsieh
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation; D002478:Cells, Cultured; D066026:Endothelial Progenitor Cells / Q000276:immunology / Q000378:metabolism*; D005312:Fetal Blood / Q000166:cytology*; D006801:Humans; D000090062:Kruppel-Like Factor 4; D017493:Leukocyte Common Antigens / Q000172:deficiency*; D039902:Multipotent Stem Cells / Q000276:immunology / Q000378:metabolism*; D010012:Osteogenesis; D010641:Phenotype; D039904:Pluripotent Stem Cells / Q000276:immunology / Q000378:metabolism*; D013997:Time Factors
chemical_list: D015415:Biomarkers; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human