The Formation And Possible Mechanisms Of Corneal Neovascularization In Diabetic Rats

Purpose:Corneal neovascularization can lead to persistent inflammation,tissue scarring and corneal edema,which can impair vision,destroy the anterior segment related to the immune pardon state cause corneal transplantation rejection.Diabetes can influence the whole body and also can change the homestasis of the cornea,in our previous study we found that large areas of corneal epithelial debridement in DM rats can induce the formation of corneal neovascularization,and there is no research on diabetic corneal neovascularization,the main purpose of this study is to explore the formation of corneal neovascularization and its mechanism in DM rats.Methods:24 SD rats were randomly selected and injected with 20 mg/mL streptozotocin(STZ)at a dose of 60 mg/kg to prepare type I diabetes mellitus(DM group)and 24 rats as normal control(control group).After 8 weeks,we used the Algerbrush ? remove all corneal epithelium from the right eye of control rats and DM rats respectively,and the left eye was used as a negative control.Corneal wound healing was observed at Oh,24hours,36hours and 48hours after corneal epithelial debridement by fluorescein sodium staining.The growth of corneal neovascularization was observed by slit lamp microscope on the 3rd,5th and 7th day after corneal epithelial debridement.Corneal sections were stained by HE to observe the structure of corneal epithelium;K12 was evaluated by immunostaining.Wnt signaling pathway related factors,VEGF and PEDF were detected by Western Blot and qPCR.Results:Compared with the control wounded group,the corneal epithelium wound healing was delayed and the neovascularization appeared in the cornea in DM wounded group;At the 7th day after debridement,the K12 fluorescence staining was positive in both wounded group,and the corneal epithelial layers was less than normal corneal epithelium and there were infiltration of inflammatory cells in corneal stroma.In the DM wounded group,Western Blot results showed that the protein levels ofLRP-6 and P-GSK-3 were significantly increased and P-P-catenin was significantly decreased.Both Western Blot and qPCR results showed that the ratio of VEGF/PEDF was significantly higher in DM wounded group and had no significant changes in other three groups.Conclusions:Diabetes induced corneal neovascularization,its pathologic mechanisms include the activation of Wnt signaling pathway,and the ratio of VEGF/PEDF was in a imbalanced state.