The role of an angiopoietin-2 inhibitor in decreasing pericyte loss in diabetic rats

Background: The ratio of pericytes:endothelial cells in normal retinal vasculature is 1:1. Pericyte loss is the earliest morphological change in the diabetic retina and predominant characteristic in diabetic retinopathy. Diabetic retinopathy is associated with angiopoietin 2 (Ang-2). The aim of this study is to determine the role of an Ang-2 inhibitor in decreasing pericyte loss in diabetic rats. Material and Methods: True experimental using rat model. Diabetic rats induced by intraperitoneal injection of streptozotocin (STZ). The samples were divided into 5 groups, injected intravitreally with vehicle (DMSO) or Ang-2 inhibitor with variation dose (10,20, and 30 μg). After one month the rat eyes were enucleated. Retinal digest preparation and HE staining was done to examine the retinal vasculature and count pericyte : endothel ratio. Results: The number of pericytes reduced by 40% (1:2.5) after five weeks of diabetes induction in the diabetic rat model. The group receiving 10 μg Ang-2 inhibitor showed the best results in terms of reducing pericyte loss (1:1.8).The group receiving 20 μg Ang-2 inhibitor had a pericyte:endothelial ratio of 1:2.1. The pericyte loss was not decreased in the group receiving 30 μg Ang-2 inhibitor (1:2.8). Linear regression analysis revealed that there was a positive relationship between administration of the Ang-2 inhibitor and a reduction in pericyte loss in diabetic rats (p > 0.05). Conclusion: Intravitreal administration of an Ang-2 inhibitor, at certain doses, reduced pericyte loss in diabetic rats.