title: Differential response of lymphatic, venous and arterial endothelial cells to angiopoietin-1 and angiopoietin-2.
abstract: BACKGROUND
  The lymphatic system complements the blood circulatory system in absorption and transport of nutrients, and in the maintenance of homeostasis. Angiopoietins 1 and 2 (Ang1 and Ang2) are regulators of both angiogenesis and lymphangiogenesis through the Tek/Tie-2 receptor tyrosine kinase. The response of endothelial cells to stimulation with either Ang1 or Ang2 is thought to be dependent upon the origin of the endothelial cells. In this study, we examined the effects of the angiopoietins on lymphatic, venous and arterial primary endothelial cells (bmLEC, bmVEC and bmAEC, respectively), which were isolated and cultured from bovine mesenteric vessels.
  
  
  RESULTS
  BmLEC, bmVEC and bmAEC cell populations all express Tie-2 and were shown to express the appropriate cellular markers Prox-1, VEGFR3, and Neuropilin-1 that define the particular origin of each preparation. We showed that while bmLECs responded slightly more readily to angiopoietin-2 (Ang2) stimulation, bmVECs and bmAECs were more sensitive to Ang1 stimulation. Furthermore, exposure of bmLECs to Ang2 induced marginally higher levels of proliferation and survival than did exposure to Ang1. However, exposure to Ang1 resulted in higher levels of migration in bmLECs than did to Ang2.
  
  
  CONCLUSIONS
  Our results suggest that although both Ang1 and Ang2 can activate the Tie-2 receptor in bmLECs, Ang1 and Ang2 may have distinct roles in mesenteric lymphatic endothelial cells.
authors.affiliation: Molecular and Cellular Biology Research, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada. vnguyen@sri.utoronto.ca <vnguyen@sri.utoronto.ca>
authors.forename: Vicky P K H
authors.initials: VP
authors.lastname: Nguyen
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Chen
authors.forename: Jason
authors.initials: J
authors.lastname: Trinh
authors.forename: Harold
authors.initials: H
authors.lastname: Kim
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Coomber
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Dumont
mesh_terms: D000595:Amino Acid Sequence; D042683:Angiopoietin-1 / Q000502:physiology*; D042702:Angiopoietin-2 / Q000502:physiology*; D000818:Animals; D002417:Cattle; D016923:Cell Death; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D042787:Receptor, TIE-2 / Q000502:physiology*; D016415:Sequence Alignment
chemical_list: D042683:Angiopoietin-1; D042702:Angiopoietin-2; D042787:Receptor, TIE-2