rAAV1-mediated Gene Over-expression of VEGF-165 and Angiopoietin-1 in Rat Cerebral Ischemia Model: An Investigation on Its Efficacy and Possible Mechanisms

To examine the effects of intra-ventricular pre-treatment with a combination of recombinant Adeno-Associated Virus vectors encoding VEGF (rAAV1-VEGF) and Ang-1 (rAAV1-Ang-1) on early stroke in a rat model of transient Middle Cerebral Artery Occlusion (tMCAO), rAAV1-VEGF/rAAV1-Ang-1 or rAAV1-VEGF/rAAV1-null vector were delivered into the lateral ventricle of each rats. After eight weeks later, the rats were subjected to tMCAO for two hours. During the early stages of ischemic reperfusion, VEGF and Ang-1 expression levels, Blood Brain Barrier (BBB) permeability and cerebral microvessel density were determined and compared statistically between groups. Cerebral infarct volume and modified Neurological Severity Scores (NSS) were also determined to evaluate the therapeutic efficacy of rAAV1-VEGF/rAAV1-Ang-1. The results show that the intra-ventricular application of rAAV1-VEGF/ rAAV1-Ang-1, eight weeks before tMCAO, results in VEGF and Ang1 overexpression, and significantly reduces Evans blue permeability following ischemia (P0.05). The microvessel density in the peri-infarct zone is significantly increased in the rAAV1-VEGF/ rAAV1-Ang-1 group as compared with the rAAV1-VEGF/rAAV1-null group(P0.05). Cerebral infarct volume and NSS in the rAAV1-VEGF/rAAV1-Ang-1 group are significantly decreased as compared with the rAAV1-VEGF/rAAV1-null group (P0.05). It is concluded that, in cerebral ischemia, the combination of Ang-1 and VEGF could be used early to promote the formation of mature neovessels and protect the injured cells, without inducing the side effects on BBB permeability. Early intra-ventricular injection of mixed rAAV1-VEGF and rAAV-Ang-1 may be a favorable therapeutic strategy in gene therapy for stroke.