Synergistic effect of angiopoietin-1 and vascular endothelial growth factor on neoangiogenesis in hypercholesterolemic rabbit model with acute hindlimb ischemia

Vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1) are essential for vascular integrity and development. The purpose of the study was to test the hypothesis that Ang1 will promote angiogenic response to VEGF in the spontaneous Watanabe heritable hypercholesterolemic (WHHL) rabbit model of acute hindlimb ischemia. Immediately after the ligation of the external iliac artery and the excision of the common and superficial femoral artery in one female WHHL rabbit, 250 microg of phVEGF(165) (n = 8), 500 microg of pAng1* (n = 8), or 250 microg of phVEGF(165) plus 500 microg of pAng1* (n = 8) was injected intramuscularly into the ischemic hindlimb muscles. Gross appearance of ischemic limb, collateral vessel formation and limb perfusion were assessed 30 days after treatment. The incidence of ischemic limb necrosis was higher in the animals treated by phVEGF(165) or by pAng1* than in those treated by phVEGF(165) plus pAng1* (100%, 75% and 14.3%, respectively; P = 0.002). Animals in the combination therapy group had a significantly higher calf blood pressure ratio at day 30 (VEGF plus Ang1* = 0.84 +/- 0.06; VEGF = 0.54 +/- 0.01; Ang1* = 0.59 +/- 0.05; P < 0.01). A combination therapy of VEGF plus Ang*1 had a significantly higher (P < 0.01) angiographic score than either therapy alone. Capillary density (P < 0.05) and capillary/muscle fiber ratio (P < 0.01) of the combination therapy group were also significantly higher than that of either therapy alone. In conclusion, Ang1 can potentiate the angiogenic response to VEGF in the hyperlipidemic rabbit model of acute hindlimb ischemia. Intramuscular administration of cytokines on revascularization of the ischemic hindlimb model of hyperlipidemic rabbit is feasible.