title: Phenotypic and functional changes in blood monocytes following adherence to endothelium.
abstract: OBJECTIVE
  Blood monocytes are known to express endothelial-like genes during co-culture with endothelium. In this study, the time-dependent change in the phenotype pattern of primary blood monocytes after adhering to endothelium is reported using a novel HLA-A2 mistyped co-culture model.
  
  
  RESULTS
  Freshly isolated human PBMCs were co-cultured with human umbilical vein endothelial cells or human coronary arterial endothelial cells of converse human leukocyte antigen A2 (HLA-A2) status. This allows the tracking of the PBMC-derived cells by HLA-A2 expression and assessment of their phenotype pattern over time. PBMCs that adhered to the endothelium at the start of the co-culture were predominantly CD11b+ blood monocytes. After 24 to 72 hours in co-culture, the endothelium-adherent monocytes acquired endothelial-like properties including the expression of endothelial nitric oxide synthase, CD105, CD144 and vascular endothelial growth factor receptor 2. The expression of monocyte/macrophage lineage antigens CD14, CD11b and CD36 were down regulated concomitantly. The adherent monocytes did not express CD115 after 1 day of co-culture. By day 6, the monocyte-derived cells expressed vascular cell adhesion molecule 1 in response to tumour necrosis factor alpha. Up to 10% of the PBMCs adhered to the endothelium. These monocyte-derived cells contributed up to 30% of the co-cultured cell layer and this was dose-dependent on the PBMC seeding density.
  
  
  CONCLUSIONS
  Human blood monocytes undergo rapid phenotype change to resemble endothelial cells after adhering to endothelium.
authors.affiliation: Lipid Research Group, The Heart Research Institute, Newtown, New South Wales, Australia. tsoc@hri.org.au
authors.forename: Colin
authors.initials: C
authors.lastname: Tso
authors.forename: Kerry-Anne
authors.initials: KA
authors.lastname: Rye
authors.forename: Philip
authors.initials: P
authors.lastname: Barter
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D002478:Cells, Cultured; D018920:Coculture Techniques / Q000379:methods; D015536:Down-Regulation; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D015789:HLA-A2 Antigen / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D008264:Macrophages / Q000378:metabolism / Q000502:physiology; D009000:Monocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010641:Phenotype; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D015789:HLA-A2 Antigen; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D052250:Nitric Oxide Synthase Type III; D040301:Vascular Endothelial Growth Factor Receptor-2