Vascular endothelial growth factor promotion of neoangiogenesis in conventional nerve grafts

The effect of vascular endothelial growth factor (VEGF) on angiogenesis and neovascularization of conventional nerve grafts was evaluated in 48 rabbits. A 2.5-cm segment of right sciatic nerve was removed and orthotopically repaired. This graft was wrapped in dialysis tubing to prevent vessel ingrowth from adjacent tissue. An osmotic pump delivered either VEGF (100 ng/h for 3 days) or control solution. Evaluation methods included angiography, vessel density, and nerve blood flow measurement at 3, 7, and 14 days. On day 3, 42% of the control nerves and 100% of VEGF-treated nerves had partial longitudinal neovascularization. Vessel density (0.84 ± 0.22 vessel/mm²) and nerve blood flow [25.34 ± 7.62 mL/(min · 100 g)] in VEGF-treated nerves were significantly higher than control group values [0.23 ± 0.13 vessel/mm² and 5.35 ± 0.99 mL/(min · 100 g)]. Progressive improvement in parameters was seen at 7 and 14 days. Vascular endothelial growth factor infusion accelerates longitudinal neoangiogenesis and shortens the nerve ischemic time to 3 days in this model. The revascularization of VEGF-treated conventional nerve grafts in a poorly vascularized bed is identical to that of grafts in a healthy bed.