Effects of avastin and dexamethasone on rat corneal neovascularization

Background A variety of factors are related with corneal neovascularization(CNV),and vascular endothelial growth factor(VEGF) plays the regulative role in the forming process of CNV.Objective This study attempted to investigate the effect of topically administered agents avastin,dexamethasone and drug combination on experimental CNV and its mechanism in rats.Methods CNV animal models were induced by putting the 3 mm filter paper soaked 1 mol/L NaOH solution at the center cornea for 30 seconds in 48 clean SD rats.20 μL of avastin (5 g/L),20 μL of dexamethasone (0.1%),avastin+dexamethasone and 20 μL of 0.9%NaCl were topically applied respectively in 12 models at 5-minute interval for 12 days.The growth of CNV was observed under the slit lamp,and the CNV area was calculated.Hematoxylin-eosin staining of cornea samples was performed for the pathological examination on the seventh day after experiment.Expression of VEGF in CNV was detected by immunohistochemistry.Results In 12 days after experiment,corneal new blood vessels were dense and thicker in 0.9% NaCl solution group,but in 0.1% dexamethasone group and avastin group,the corneal new blood vessels were sparse and thinner.Less corneal new blood vessels were seen in avastin+dexamethasone group.The area of CNV was smaller in 0.1% dexamethasone group and avastin+dexamethasone group and avastin group in 3,6 and 12 days after experiment in comparison with 0.9% NaCl solution group (all P0.01).The area of CNV was significantly decreased in avastin group compared with 0.1% dexamethasone group and avastin+dexamethasone group in various time points (all P0.01).No significant difference in CNV area was found between 0.1% dexamethasone group and avastin group (P0.05).Infiltration of lots of inflammatory cells and vascular canals were seen in 0.9% NaCl solution group,but little of inflammatory cells and vascular canals were in dexamethasone group,avastin group and avastin+dexamethasone group.Immunohistochemistry revealed that the expression of VEGF was mainly in CNV zone and corneal epithelial layer.Expression of VEGF was more in 0.9% NaCl group compared with dexamethasone group and avastin group,and that in avastin+dexamethasone group was weaker.Conclusion Topical application of avastin and dexamethasone can inhibit alkali-induced CNV.Avastin and dexamethasone show a synergistic effect in suppressing the expression of VEGF and inflammation cells.