title: Functional ephrin-B2 expression for promotive interaction between arterial and venous vessels in postnatal neovascularization.
abstract: BACKGROUND
  Ephrin-B2, one of the transmembrane ligands, is a genetic marker of arterial endothelial cells (ECs) at embryonic stages and is essential for cardiovascular development, but its roles in ischemic cardiovascular disease are not well understood. In this study, we focused on the function of ephrin-B2 in postnatal neovascularization.
  
  
  RESULTS
  We found that ephrin-B2 is exclusively expressed and significantly upregulated in the arterial vasculature after the initial angiogenic responses in tissue ischemia. Upregulation of ephrin-B2 is also observed in EC cordlike formation in vitro. Interestingly, ephrin-B2 expression on ECs was enhanced by promotive angiogenic growth factors, such as vascular endothelial growth factor, basic fibroblast growth factor, and hepatocyte growth factor, whereas it was attenuated by angiopoietin-1, a factor for blood vessel maturation. Moreover, an ephrin-B2-rich environment was shown to induce neovascularization mainly through venous angiogenesis in an in vivo cornea micropocket assay.
  
  
  CONCLUSIONS
  Our study indicates that the ephrin-B2 ligand is likely to have functional expression on angiogenic arterial ECs and induce a subsequent promotive effect on venous vessels during postnatal neovascularization.
authors.affiliation: Division of Cardiovascular Research and Medicine, St Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Mass 02135, USA. shin559182@aol.com
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Hayashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Asahara
authors.forename: Haruchika
authors.initials: H
authors.lastname: Masuda
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Isner
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Losordo
mesh_terms: D000818:Animals; D001158:Arteries; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D036388:Ephrin-B2 / Q000235:genetics* / Q000502:physiology*; D006133:Growth Substances / Q000494:pharmacology; D006614:Hindlimb / Q000098:blood supply; D006801:Humans; D007511:Ischemia; D016850:Limbus Corneae / Q000098:blood supply; D051379:Mice; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic; D015854:Up-Regulation / Q000187:drug effects*; D014680:Veins
chemical_list: D036388:Ephrin-B2; D006133:Growth Substances