Late Administration of Human Recombinant Vascular Endothelial Growth Factor (rhVEGF165) Improves Functional Outcome after Embolic Stroke in Rat
Transient and permanent middle cerebral artery (MCA) occlusion in rat evokes increased expression of VEGF in ischemic brain. The biological role of VEGF in stroke is unknown. We tested the hypothesis that administration of VEGF at a late stage of stroke enhances angiogenesis and improves functional outcome in stroke. Male Wistar rats (n=27) were subjected to MCA occlusion using a well described embolic stroke model. Forty-eight hours after embolization, rhVEGF165 or saline was intravenously infused to rats at a dose of 1mg/kg over 4 hr interval. Angiogenesis was examined in three dimensions by a laser scanning confocal microscope. Functional neurological tests (rotarod and adhesive removal tests) were measured. To examine whether rhVEGF165 enhances angiogenesis, rats were sacrificed 9 days after ischemia and to examine whether rhVEGF165 improves long term functional recovery, rats were sacrificed 28 days after ischemia. Compared with the saline treated rats (n=5), treatment with rhVEGF165 (n=5) significantly (p<0.05) increased numbers of capillaries with diameters within 3 μm in the penumbra of the cortex 9 days after ischemia. In addition, rats treated with rhVEGF165 (n=7) exhibited significant (p<0.05) improvement on the rotarod test at 7, 14, and 28 days after stroke compared with the saline treated rats (n=10). The adhesive removal test showed significant (p<0.05) improvement at 28 days. Brain tissue obtained at 28 days after ischemia exhibited more small vessels in the ipsilateral ischemic border zone in rats treated with rhVEGF165 when compared with the saline treated rats. Our data demonstrate that rhVEGF165 significantly enhances angiogenesis in ischemic brain and improves functional neurological recovery when administered to rats 48 hr after stroke.