Suppression of angiogenic response in local vein wall is associated with reduced thrombus resolution

Thromb Res. 2014 Sep;134(3):682-5. doi: 10.1016/j.thromres.2014.06.028. Epub 2014 Jul 5.

Abstract

Introduction: 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.

Materials and 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.

Keywords: Anti-angiogenesis; Hypoxia; Resolution.

MeSH terms

  • 2-Methoxyestradiol
  • Angiogenesis Inhibitors / toxicity*
  • Animals
  • Cell Proliferation / drug effects
  • Disease Models, Animal
  • Down-Regulation
  • Estradiol / analogs & derivatives*
  • Estradiol / toxicity
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Male
  • Mice, Inbred C57BL
  • Neovascularization, Physiologic / drug effects*
  • Placenta Growth Factor
  • Pregnancy Proteins / metabolism
  • Time Factors
  • Vascular Endothelial Growth Factor A / metabolism
  • Vena Cava, Inferior / drug effects*
  • Vena Cava, Inferior / metabolism
  • Vena Cava, Inferior / pathology
  • Vena Cava, Inferior / physiopathology
  • Venous Thrombosis / chemically induced*
  • Venous Thrombosis / metabolism
  • Venous Thrombosis / pathology
  • Venous Thrombosis / physiopathology

Substances

  • Angiogenesis Inhibitors
  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Pgf protein, mouse
  • Pregnancy Proteins
  • Vascular Endothelial Growth Factor A
  • vascular endothelial growth factor A, mouse
  • Placenta Growth Factor
  • Estradiol
  • 2-Methoxyestradiol