Inhibitory Effect Of Small Interfering RNA Targeting VEGF On Corneal Neovascularization In The Rabbits

Background: Vascular endothelial growth factor (VEGF) is the main growth factor which induced neovascularization in corneas. Investigating its mechanism in corneal neovascularization and regulating its expression will be the effective route of prerventing and healing corneal neovascularization diseases.Purpose: To investigate the effect of VEGF small interefering RNA (VEGFsiRNA)on the expression of VEGFmRNA and protein in corneal tissues in rabbits after alkaline cauterization of the cornea and evaluate its role in curing corneal neovascularization diseases.Methods:This study was divided into three parts. Part I: CNV was induced in vivo by alkaline cauterization (1mol/L NaOH)of the corneas in 25 rabbits. Cornea neovascularization were evaluated by morphometric analysis at different time points after alkaline burn (1, 3, 5, 7, 14d) . The expression of VEGF in corneas was detected by immunohistochemistry. Part II: CNV was induced in vivo by alkaline cauterization of the corneas in 25 rabbits. Using liposome (LF2000) as vector, VEGFsiRNA recombinant plasmid was injected into the subconjunctiva of the right eye ,and pSilencer2.1-U6 hygro was injected into the subconjunctiva of the left eye as control. 1 to 14 days post-cautery,CNV was evaluated with morphometric analysis. Part III: After the morphometric analysis , the expression of VEGFmRNA in rabbit corneas was evaluated by reverse transcription-polymerase chain reaction (RT-PCR), and the expression of VEGF protein in rabbit corneas was detected by immunohistochemical analysis 1, 3, 5, 7, 14 days after alkaline cautery of corneas.Results: Part I: The expression of VEGF increased at 24 hours after cautery, peaded on 5d after cautery, decreased on 7d and significantly decreased to near baseline on 14d. After alkaline burn, the expression of VEGF paralleled to the growth of CNV in rabbit corneas. Part II: Comparing with the control eyes, the lenghth and area of CNV in the eyes treated with VEGFsiRNA recombinant plasmid at different time points after alkaline cauterization were shortened and reduced significantly (P<0.05) . Part III: Compared with the control eyes, the expression of VEGF mRNA and protein in corneas of eyes treated with VEGFsiRNA recombinant plasmid was significantly downregulated at different time points after alkaline cauterization (P<0.05 ) .Conclusions: This investigation suggests that the expression of VEGF correlated with angiogenesis induced by alkaline cautery in the rabbit corneas and played an important role in rabbit corneal neovascularization. VEGFsiRNA can effectively inhibit the expression of VEGFmRNA and VEGF protein in corneas in rabbits after alkali burn, and suppress the development of CNV in rabbits after alkaline cauterization.