Reduction of experimental diabetic vascular leakage and pericyte apoptosis in mice by delivery of αA-crystallin with a recombinant adenovirus

The study aimed to evaluate the efficacy of recombinant adenovirus expressing alpha A-crystallin (Ad-alpha Ac-Gfp) in reducing pericyte loss within retinal vasculature in early diabetes. Diabetes was induced by streptozotocin injection into C57BL/6 mice. Ad-alpha Ac-Gfp was delivered by intravitreous injection to the right eyes of mice 2 weeks before induction of diabetes. Vascular leakage was determined by fluorescent angiography, Evans Blue leakage assay and leucocyte adhesion test. Production of alpha A-crystallin was analysed by immunoblotting and double immunostaining and pericyte loss was analysed by pericyte count. Vessel leakage and pericyte loss were observed in the streptozotocin-induced diabetic retina. Decreased abundance of alpha A-crystallin in retinas 2 and 6 months after the induction of diabetes was confirmed by two-dimensional electrophoretic analysis, immunoblotting and RT-PCR. Double immunofluorescence staining for alpha A-crystallin and NG2 chondroitin sulphate proteoglycan revealed that alpha A-crystallin was predominantly produced in the retinal pericyte and that the number of alpha A-crystallin-producing pericytes decreased in the diabetic retina. Retinal infection with Ad-alpha Ac-Gfp led to decreased pericyte loss and vascular leakage compared with control. Intravitreal delivery of Ad-alpha Ac-Gfp protects against vascular leakage in the streptozotocin-induced model of diabetes. This effect is associated with the inhibition of diabetic retinal pericyte loss in early diabetes, suggesting that alpha A-crystallin has a role in preventing the pathogenesis of early diabetic retinopathy.