Adeno-associated viral-vector-mediated hypoxia-inducible vascular endothelial growth factor gene expression attenuates ischemic brain injury after focal cerebral ischemia in mice.

OBJECTIVE

Exogenous delivery of vascular endothelial growth factor gene (VEGF) may provide a useful approach to the treatment of brain ischemia. We investigated the use of a hypoxia-responsive element to control VEGF expression given for neuroprotection.

METHODS

Three groups (n=36) of mice received AAVH9-VEGF, AAVH9-lacZ, or saline injection. Five days after gene transfer, the mice underwent 45 minutes of transient middle cerebral artery occlusion (tMCAO) followed by 1 to 7 days of reperfusion. Infarct volume was determined using cresyl violet staining; neuronal injury was examined using TUNEL, cleaved caspase-3, and fluoro-Jade B staining.

RESULTS

Hypoxia-inducible factor-1 (HIF-1) was overexpressed after tMCAO in the ischemic hemisphere in the brain. Expression of lacZ, mediated by AAV-lacZ, was seen before and after tMCAO; however, AAVH9-lacZ-mediated lacZ expression was detected only after tMCAO. Infarct volume was smaller in the AAVH9-VEGF-transduced group compared with AAVH9-lacZ and saline groups (55% reduction, P<0.05) with reduced TUNEL (29+/-5% and 30+/-7% versus 12+/-3%, P<0.05), cleaved caspase-3 (20+/-3% and 21+/-5% versus 13+/-4%, P<0.05) and fluoro-Jade B (23+/-3% and 24+/-5% versus 12+/-5%, P<0.05) -positive neurons, respectively.

CONCLUSIONS

Exogenous expression of VEGF through AAVH9-VEGF gene transfer 5 days before the onset of ischemia provides neuroprotection. Hypoxia-responsive element is a viable strategy of restricting VEGF expression to areas of ischemia to minimize adverse effects of therapy on adjacent normal parenchyma.