scAAV2-Mediated C3 Transferase Gene Therapy in a Rat Model with Retinal Ischemia/Reperfusion Injuries

Glaucoma is characterized by retinal ganglion cell (RGC) death and axonal loss. Therefore, neuroprotection is important in treating glaucoma. In this study, we explored whether exoenzyme C3 transferase (C3)-based gene therapy could protect retinas in an ischemia/reperfusion (I/R) injury rat model. Self-complementary adeno-associated virus 2 (scAAV2) vectors encoding either C3 protein (scAAV2-C3) or enhanced green fluorescence protein (scAAV2-EGFP) were intravitreally delivered into both eyes of rats, and I/R models (acute ocular hypertension) were made in one eye of each rat at day 7 after the injection. The rats were divided into six groups: scAAV2-C3, scAAV2-C3 with I/R, scAAV2-EGFP, scAAV2-EGFP with I/R, blank control, and blank control with I/R. TUNEL (terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick end labeling), immunohistochemistry of cleaved caspase-3, NeuN and Brn-3a, and H&E staining were used to detect apoptotic cells and other changes in the retina. The results showed that scAAV2-C3 significantly reduced the number of apoptotic RGCs and decreased cell loss in the ganglion cell layer after I/R injury, and the I/R-injured retinas treated with scAAV2-C3 were the thickest in all I/R groups. These results suggest that scAAV2-mediated C3 gene therapy is able to protect the rat retina from I/R injury and has potential in the treatment of glaucoma in the future.