Therapeutic angiogenesis/arteriogenesis in the chronic ischemic rabbit hindlimb: effect of venous basic fibroblast growth factor retroinfusion.

Therapeutic induction of angiogenesis has been shown in experimental hindlimb ischemia. An alternative to targeting the ischemic hindlimb tissue via the severely stenosed or occluded artery consists in the intact venous system, e.g., by retroinfusion. We tested whether basic fibroblast growth factor (bFGF) enhances angiogenesis induction. Therefore, we applied bFGF retrogradely as compared to intramuscular application. Furthermore, we assessed whether bFGF-induced angiogenesis was enhanced by low-dose VEGF coapplication. Chronic hindlimb ischemia in rabbits was established by excision of the femoral artery at day 0 (d0). At d7, baseline collateral number in the ischemic limb and collateral flow velocity of contrast agent (frame count score) were assessed. Thereafter, saline solution (control group) or bFGF (20 microg/kg) with or without VEGF (10 microg/kg) was retroinfused through the femoral vein. Alternatively, bFGF (20 microg/kg) was injected into thigh and calf muscles. At d35, collateral growth and flow velocity were quantified, and tissue samples were analyzed for capillary density. In the untreated control group, capillary/muscle fiber (C/FM) ratio of the ischemic limb was 0.87 +/- 0.12, and collateral number as well as frame count score at -d35 did not change compared to d7 (107% +/- 7% and 109% +/- 10% of baseline, respectively). Retrograde application of bFGF induced capillary and collateral growth (C/FM ratio 1.56 +/- 0.19 and frame count 161% +/- 29% of baseline), resulting in enhanced flow velocity (143% +/- 13%), similar to the intramuscular application of bFGF. Additional low-dose VEGF retroinfusion did not further increase capillary/collateral growth (1.49 +/- 0.08 and 172% +/- 26%) nor perfusion velocity (149% +/- 7%). The authors conclude that bFGF retroinfusion is a feasible approach of inducing angiogenesis and arteriogenesis in an ischemic hindlimb, resulting in increased blood perfusion, which was not further extended by additional low-dose VEGF coapplication.