Protective Effect of Simvastatin on Induced Diabetic Retinopathy and Endothelial Progenitor Cells in Adult Male Albino Rat, Histological and Immunohistochemical Study

Background and Objectives: Diabetic retinopathy (DR) is one of the main causes of blindness and thereis no available treatment for complete cure. This study was planned to evaluate the potential protectiveeffects of simvastatin in a rat model of DR with special emphasis on endothelial progenitor cells (EPCs).Methods: Thirty adult male albino rats were equally divided into: Group І (control group), Group II(diabetic group) and Group III (diabetic/simvastatin treated group). Diabetes was induced by intraperitonealinjection of streptozotocin (STZ) 50 mg/Kg /rat in 20 adult male albino rats. Simvastatin was administeredas 20 mg/Kg/rat 48 hours after STZ injection via oral route. Body weight and blood glucose levels weremeasured weekly for 1 month. Flowcytometry was used to detect circulating endothelial progenitor cells(EPCs). Retinal specimens were processed for hematoxylin and eosin staining as well as CD31 andcaspase 3 immunohistochemistry. Morphometric analysis included measurement of retinal thickness,number of ganglion cells, number of CD31 positive cells and area percent of caspase 3 positive immunereaction.All results were statistically analyzed.Results: Flowcytometry showed that simvastatin was able to increase the percentage of circulating EPCsin group III compared to group II. Group II showed histological features of DR, CD 31 immuno-reactionwas comparable to control and caspase 3 immuno-reaction increased significantly compared to control.Group III showed improved features of DR, significant increase in CD 31 and decrease in caspase 3immuno-reactivity.Conclusions: These results suggest that simvastatin has protective effects on DR and might be consideredas promising therapeutic agent for it.