Suppression of choroidal neovascularization by adeno-associated virus vector expressing angiostatin

PURPOSE. To test the efficacy of a recombinant adeno-associated virus (rAAV ) vector that expresses mouse angiostatin in suppressing experimental choro idal neovascularization (CN-V) in a rat model. METHODS. An rAAV vector, rAAV-angiostatin, was constructed to deliver the m ouse angiostatin gene. rAAV-angiostatin and a control virus, rAAV-lacZ, wer e delivered in vivo by subretinal injection in Brown Norway rats, and the d elivery was confirmed by reverse-transcriptase polymerase chain reaction (R T-PCR). For a CNV suppression experiment, CNV was generated by fundus krypt on laser photocoagulation 7 days after the viral vector injection and was e valuated by fluorescein angiography (FA) and histology. Apoptosis in retina was analyzed using the TUNEL assay. Inflammation in the retina was investi gated by immunohistochemistry, using antibodies that recognize lymphocytes. RESULTS. rAAV-angiostatin injection led to sustained expression of the angi ostatin gene in chorioretinal tissue for up to150 days. FA analysis reveale d significant reduction of the average sizes of CNV lesions in rAAV-angiost atin-injected eyes when compared with rAAV-lacZ-injected eyes at both 14 (P = 0.019) and 150 (P = 0.010) days after injection. Moreover, histologic an alysis of CNV lesions also revealed significantly smaller lesions in rAAV-a ngiostatin-injected eyes (P = 0.004). As for adverse effects, rAAV-angiosta tin injection did not cause inflammation or apoptosis of cells in retina an d choroid. CONCLUSIONS. This is the first report that subretinal injection of rAAV-ang iostatin can significantly reduce the sizes of CNV lesions. This and the ab sence of apoptosis and inflammation in chorioretinal tissue indicate the fe asibility of a gene therapy approach for treatment of CNV disease.