title: Hyperhomocyst(e)inemia impairs angiogenesis in a murine model of limb ischemia.
abstract: Hyperhomocyst(e)inemia (HH) is an established independent risk factor for coronary, cerebral and peripheral vascular diseases. Recent studies have indicated that certain cardiovascular risk factors, including diabetes and hypercholesterolemia, impair expression of vascular endothelial growth factor (VEGF) and endogenous angiogenesis. In this study, we investigate the impact of moderate HH on angiogenesis and VEGF pathway in a mouse model of hindlimb ischemia. Upon induction of unilateral hindlimb ischemia, endogenous angiogenesis, expression of VEGF, and phosphorylation of the VEGF receptor Flk-1 were evaluated in mice heterozygous for a deletion of the cystathionine beta-synthase gene (CBS) and compared with those observed in CBS+/+ mice. CBS+/- mice exhibit moderate HH, as demonstrated by measuring plasma total homocyst(e)ine (tHcy) levels, which were significantly higher in these animals compared with CBS+/+ mice (4.77 +/- 0.82 vs 2.10 +/- 0.28, p < 0.01). Twenty-eight days after induction of ischemia, hindlimb blood flow was significantly reduced in CBS+/- mice compared with CBS+/+ animals (0.49 +/- 0.03, n = 12 vs 0.71 +/- 0.09, n = 10; p < 0.05). In addition, there was a significant negative correlation between plasma homocyst(e)ine levels and the laser Doppler perfusion ratio in CBS+/- mice (p = 0.0087, r = -0.7171). While VEGF expression and Flk-1 phosphorylation were not impaired in the ischemic muscles of CBS+/- mice, phosphorylation of the endothelial cell survival factor Akt was significantly inhibited by homocyst(e)ine in a dose-dependent manner in human umbilical vein endothelial cell (HUVECs) in vitro. In conclusion, our findings demonstrate that endogenous angiogenesis is inversely related to plasma levels of homocyst(e)ine in genetically engineered, heterozygous mice with moderate HH. This impairment, however, is not dependent on reduced expression of VEGF or impaired phosphorylation of its receptor Flk-1. In contrast, our data suggest that impaired Akt phosphorylation mediates the impairment of angiogenesis associated with HH.
authors.affiliation: Department of Medicine (Cardiovascular Research), Caritas St Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135-2997, USA.
authors.forename: Marta
authors.initials: M
authors.lastname: Bosch-Marcé
authors.forename: Roberto
authors.initials: R
authors.lastname: Pola
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Wecker
authors.forename: Marcy
authors.initials: M
authors.lastname: Silver
authors.forename: Alberto
authors.initials: A
authors.lastname: Weber
authors.forename: Corinne
authors.initials: C
authors.lastname: Luedemann
authors.forename: Cynthia
authors.initials: C
authors.lastname: Curry
authors.forename: Toshinori
authors.initials: T
authors.lastname: Murayama
authors.forename: Marianne
authors.initials: M
authors.lastname: Kearney
authors.forename: Young-sup
authors.initials: YS
authors.lastname: Yoon
authors.forename: M René
authors.initials: MR
authors.lastname: Malinow
authors.forename: Takayuki
authors.initials: T
authors.lastname: Asahara
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Isner
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Losordo
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D020138:Hyperhomocysteinemia / Q000503:physiopathology*; D007511:Ischemia / Q000097:blood*; D051379:Mice; D008815:Mice, Inbred Strains; D018919:Neovascularization, Physiologic / Q000502:physiology*; D010766:Phosphorylation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2