Protective effect of rAAV2-NTF2 on blood-retinal barrier damage in diabetic rats

AIM: To explore the effect of rAAV2-NTF2 on the blood-retinal barrier damage in early stage diabetic retinopathy. METHODS: Retinal vasculature was observed by Evans blue. NTF2 gene was cloned into adeno-associated virus vector pSNAV. The recombinant pSNAV-NTF2 was transfected into BHK cells. After purification, high-titer rAAV2-NTF2. rAAV2-NTF2 at dose of 4 μL (titer 1.0×1012) were injected into left eyes and rAAV2-EGFP at the same does and titer were injected into the right eyes of 36 rats. After 1 month, diabetes mellitus were induced by STZ. One month after onset of diabetes, EB at a dose of 45 mg/kg was intravenously injected into the rats. Two hours later, both eyes were enucleated immediately after perfusion of 1% PFA-citric acid buffer solution. The retinas were then dissected away and placed in formamide to extract the dye. The concentration of dye was measured by spectrophotometer. RESULTS: Evans blue was contained in normal retinal vessels without leakage, with a very low level of background fluorescence. The vessels staining of diabetic rats’ retina showed increasing fluorescence, indicating the retina-blood barrier damage. Dye concentration, representing the degree of the BRB injury, was higher in retina of 1 month diabetic rats than that in normal rats (4.67 times, P<0.01), indicating retina-blood barrier break-down. Diabetic rats with rAAV2-NTF2 intravitreal injection showed decreased BRB breakdown (P<0.05). CONCLUSION: High expression of NTF-2 decreases the BRB dysfunction in DM rats.