Effects of intravitreal and intraperitoneal apigenin injection on retinal endothelial cell proliferation, retinal morphology and apoptotic cell death in an oxygen induced retinopathy in vivo mouse model

The aim of our study was to investigate the effects of different concentrations of Apigenin on retinal endothelial cell proliferation, retinal morphological structure and apoptotic cell death in an in vivo oxygen-induced retinopathy (OIR) mouse model. A total of 50 newborn C57BL/6J mice were included in the study. Thirty-five mice, with their mothers, were exposed to 75 ± 2 % oxygen between postnatal 7-12th days and the injections were held on postnatal 12th day after they were taken back to room air (21% oxygen). On postnatal 17th day, mice were enucleated and quantitative analysis of preretinal neovascularization, apoptotic cell death and morphological structure analyses were performed. For the analyses, 10 groups, each consisting of 5 mice were organised. The groups were represented as: Group-A without any oxygen exposure or injections; Group-B injected with 1 μl intravitreal sterile dimethyl sulfoxide (DMSO) solution without oxygen exposure; Group-C oxygen exposed but not treated; Group-D injected with intravitreal 1 μl sterile DMSO solution after oxygen exposure; Group-E and -F treated with 10 μg/ml and 20 μg/ml intravitreal Apigenin respectively after oxygen exposure; Group-G and-H treated with 10 mg/kg and 20mg/kg intraperitoneal Apigenin respectively after oxygen exposure; Group-I injected with 3 μl intraperitoneal sterile DMSO solution without oxygen exposure; Group-J injected with 3 μl intraperitoneal sterile DMSO solution after oxygen exposure. When the control groups were compared, a significant increase in endothelial cell and atypical mitochondrion counts were detected in the oxygen exposed groups (p<0,0001), while no significant difference was noted in apoptotic cell counts. When compared with Group-C, statistically significant decrease in endothelial cell, atypical mitochondrion and apoptotic cell counts of Group-E, -F, -G and -H were observed (p<0,0001 for all). None of the groups with Apigenin injections revealed cystic degeneration nor cell loss under light microscopy. In conclusion, Apigenin supresses the neovascularisation, mitochondrial dysmorphology and apoptosis and is promising for the treatment of ocular neovascular diseases.