title: Suppression of angiogenic response in local vein wall is associated with reduced thrombus resolution.
abstract: BACKGROUND
  The formation of new vascular channels within and around venous thrombus contributes to its resolution. Neovascularisation arising from the surrounding vein may facilitate this process. Treatment of cancer patients with anti-angiogenic agents can lead to increased incidence of venous thromboembolic events, but the effect of these agents on the processes that govern thrombus resolution are unclear. The aim of this study was to determine the effect of anti-angiogenic treatment with 2-methoxyestradiol (2ME) on (i) angiogenic response in the thrombosed vein and (ii) venous thrombus resolution.
  
  
  METHODS
  Venous thrombus was induced in the inferior vena cava (IVC) of 36 adult male BALB/C mice. Thrombosed mice received either the anti-angiogenic agent, 2ME (150 mg/kg/day, i/p), or vehicle control (n=18/group). In the thrombosed IVC of both groups: hypoxia-inducible factor (HIF) 1α, and its angiogenic targets, vascular endothelial growth factor (VEGF) and placental growth factor (PLGF), were quantified using enzyme-linked immunosorbent assays at days 1 and 10 post-thrombus induction (n=6/group); and inflammatory cell content, cell proliferation, and vein recanalisation were quantified using immunostaining and image analysis at day 10 (n=6/group).
  
  
  RESULTS
  In the IVC of mice treated with 2ME compared with control: HIF1α (P<0.005 and P<0.02), VEGF (P<0.005 and P<0.02), and PLGF levels (P<0.01 and P<0.001) were reduced at days 1 and 10 post-thrombus induction respectively, and macrophage content (P<0.005), neutrophil content (P<0.01), vein recanalistion (P<0.05), and thrombus resolution (P<0.001) were also reduced at day 10.
  
  
  CONCLUSIONS
  Anti-angiogenic treatment with 2ME supressed the HIF1-mediated angiogenic drive in local vein wall and attenuated venous thrombus resolution. The potential pro-thrombotic effect of anti-angiogenic agents should be carefully considered when managing venous thromboembolic events in cancer patients.
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, UK. Electronic address: cee31@cam.ac.uk.
authors.forename: Colin E
authors.initials: CE
authors.lastname: Evans
authors.affiliation: King's College London, BHF Centre of Research Excellence & NIHR Biomedical Research Centre at King's Health Partners, Academic Department of Vascular Surgery, UK.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Grover
authors.affiliation: King's College London, BHF Centre of Research Excellence & NIHR Biomedical Research Centre at King's Health Partners, Academic Department of Vascular Surgery, UK.
authors.forename: Prakash
authors.initials: P
authors.lastname: Saha
authors.affiliation: King's College London, BHF Centre of Research Excellence & NIHR Biomedical Research Centre at King's Health Partners, Academic Department of Vascular Surgery, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Humphries
authors.affiliation: Department of Molecular and Cell Biology, University of Texas at Dallas, USA.
authors.forename: Jung-Whan
authors.initials: JW
authors.lastname: Kim
authors.affiliation: King's College London, BHF Centre of Research Excellence & NIHR Biomedical Research Centre at King's Health Partners, Academic Department of Vascular Surgery, UK.
authors.forename: Bijan
authors.initials: B
authors.lastname: Modarai
authors.affiliation: King's College London, BHF Centre of Research Excellence & NIHR Biomedical Research Centre at King's Health Partners, Academic Department of Vascular Surgery, UK.
authors.forename: Alberto
authors.initials: A
authors.lastname: Smith
mesh_terms: D000077584:2-Methoxyestradiol; D020533:Angiogenesis Inhibitors / Q000633:toxicity*; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D015536:Down-Regulation; D004958:Estradiol / Q000031:analogs & derivatives* / Q000633:toxicity; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000378:metabolism; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014682:Vena Cava, Inferior / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D020246:Venous Thrombosis / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology
chemical_list: D020533:Angiogenesis Inhibitors; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C000608037:Pgf protein, mouse; D011257:Pregnancy Proteins; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D000072483:Placenta Growth Factor; D004958:Estradiol; D000077584:2-Methoxyestradiol
keywords: Anti-angiogenesis; Hypoxia; Resolution