Effect of intravitreal and intraperitoneal cyanidine-3-glucoside injection on retinal neovascularization, mitochondrial morphology and apoptotic cell death in an oxygen induced retinopathy mouse model

The aim of the study was to evaluate the effects of different Cyanidin-3-Glucoside concentrations on retinal endothelial cell proliferation, retinal structure and apoptotic activity after intravitreal and intraperitoneal injection in an oxygen induced retinopathy (OIR) mouse model. A total of 40 of C57BL⁄ J6 mice were used, 20 being exposed to 75 ± 2% oxygen from postnatal day 7 to day 12. On day 12, in group D-S 1µl intravitreal DMSO was injected in one eye. In group E 300 ng/µl intravitreal Cyanidin-3-Glucoside (IVC), in group F 600 ng/µl IVC was injected. In group G 0.05mg/kg intraperitoneal Cyanidin-3-Glucoside (IPC), in group H 0.1mg/kg IPC was injected. Control group C mice were exposed to hyperoxia with 75%±2 oxygen without receiving any injection. Control group B-S was maintained in room air and received 1µl of sterile DMSO solution intravitreally. Non-exposed mice served as negative controls (group A). Neovascularization was quantified by counting the endothelial cell proliferation on the vitreal side of the inner limiting membrane of the retina. Histological and ultrastructural changes were examined by light and electron microscopy. Terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling (TUNEL) was used to detect apoptosis. The endothelial cell count per histological section was lower in groups E (p<0.0001) and F (p<0.0001) compared with group D-S. IPC high dose group H also had lower cell counts compared with groups C and D-S (p<0.0001 and p=0.014 respectively). Electron microscopy revealed hyperoxia induced mitochondrial dysmorphology in group C and D-S. Mitochondrial dysmorphology displayed significant decrease in IVC and high dose IPC injected eyes. Apoptotic cell death did not differ from the control groups in low dose IVC and both IPA groups, but was found significantly higher in high dose IVC group (p<0.0001) In conclusion, Cyanidin-3-Glucoside suppresses endothelial cell proliferation in OIR C57BL⁄J6 mouse model, leads to a decrease in hyperoxia-induced mitochondrial dysmorphology but increases apoptotic cell death in a dose-dependent fashion.