Inhibition Of Experimental Corneal Neovascularization In Rats By Subconjunctival Injection Of Bevacizumab

Purpose: To study and evaluate the effect of subconjunctival injection of bevacizumab on experimental corneal neovascularization in rats induced by corneal suture and the expression of corenal vascular endothelial growth factor.Methods: The rat model of corneal neovascularization(CNV) was induced by corneal suture. Seventy two wistar rats were randomly divided into experimental group and control group, and each group was then randomly divided into 4 groups (A1,A2,B1,B2 and C1,C2,D1,D2). Group Al and A2 were treated subconjunctivally with a single dose of 0.02ml(25mg/ml) of bevacizumab,3 or 5 days after corneal suture respectively; Group B1 and B2 received subconjunctival bevacizumab 0.05ml(25mg/ml) 3 days or 5 days after suture respectively;The control group C1,C2,D1,D2 were received subconjunctival saline with different dosage at different times(group C1,0.02ml, day 3; group C2,0.02ml, day 5; group D1,0.05ml, day 5;group D2,0.05ml, day 5). The occurrence and development of CNV were observed by slit-lamp microscope, and length and area of CNV were calculated. All rats were observed clinically 14 days after suture, and six eyes were obtained each time on days 7,11,14 post-suture. The binding ability of bevacizumab to murine VEGF was analyzed by histological analysis and immunostaining.Results:1. In the bevacizumab-treated eyes, the vascular area was lower than in the saline-treated eyes. The treated group was statistical differences compared with the control group; when vascular area were compared between the bevacizumab-treated group, there was statistical differences between the experimental group A1 and A2, A1 and B1,B1 and A2, B1 and B2,A2 and B2 on days 7,11,14 post-suture.2. The histopathological findings showed that the inflammation cells and the neovascularity in the experimental group was less than in the control group. On day 7 post-suture, the quantities of vessels in experimental groups were respectively less than in control groups(p<0.05); On day 11 post-suture, the quantities of vessels in experimental groups were respectively less than in control groups(p<0.05), the difference between group A2 and group B1 was statistically significant(p<0.05). On the fourteenth day, the quantities of vessels in experimental groups were respectively less than in control groups(p<0.05), the difference between experimental groups A1 and A2, A1 and B1,B1 and A2, B1 and B2, A2 and B2 was statistically significant(p <0.05).3. The expression of VEGF markedly increased in saline-treated group compared with bevacizumab. On the seventh day, the number of positive cells in experimental groups was respectively smaller than in control groups(p<0.05), the difference between group A2 and group B1 was statistically significant(p<0.05). On day 11 post-surgery, the number of positive cells in experimental groups was respectively smaller than in control groups(p<0.05), the difference between group A2 and group B1, A1 and B1,B1 and B2 was statistically significant(p<0.05). On the fourteenth day, the quantities of positive cells in experimental groups were respectively less than in control groups(p<0.05), the difference between experimental groups A1 and A2, A1 and B1, B1 and A2, B1 and B2, A2 and B2 was statistically significant(p<0.05)4. Used correlation analysis to analyze the area of CNV and the amount of vessels, and the area of CNV and the amount of positive cells on the fourteenth day,, the value of r is 0.908 and 0.867 respectively, p<0.01, it showed that positive correlation existed between the area of CNV and the amount of vessels, and the area of CNV and the quantities of vessels.Conclusion: 1. Corneal suture can induce corneal neovascularition in rats cornea. As a highly specific vascular endothelial growth factor of vascular endothelial cells, the expression and distribution of VEGF was positive correlated with the corneal neovascularization.2. Subconjunctival injection of bevacizumab could inhibit the progressive corneal neovascularition in rats corneas induced by corneal suture.3.The treatment of groups which were received Bevacizumab 3 days after corneal suture was more effective than the groups received Bevacizumab 5 days after corneal suture, treatment is more effective when the administrated time is more earlier; the inhibition of 0.05ml(25mg/ml) of bevacizumab was better than 0.02ml(25mg/ml) of Bevacizumab.4.We should do more experiments to evaluate whether the lower drug concentration and lower dosage of Avastin is effective.