Expression Of VEGF-C And VEGFR-3 In Rat Cornea And Lymphangiogenesis After Alkaline Burn

Objective: To investigate the expression of VEGF-C, VEGFR-3 and molecular mechanisms of lymphangiogenesis in rat corne after alkali injury.Method : 64 SD rats were randomly assigned to eight different study groups(n=8 per group): normal corneal group(0d),the 1st day group, the 3rd day group, the 5th day group,the 7th day group,the 14th day group,the 21st day group and the 28th day group. The rat alkali injured corneal models were made by NaOH(1mmol/L). The right eye of rat was used as experimental alkaline burn model. Lymphangiogenesis was labeled with LYVE-1 and hemangiogenesis was labeled with CD34 and the expression of VEGF-C and VEGFR-3 proteins in rat cornea were detected by using immunohistochemical assay at day 0 and day 1,3,5,7,14,21,28 after injury. In addition,, 16 SD rats were randomly assigned to normal cornea group and the 14th day group(n=8 per group) and were used to observe the ultrastructure of lymphatic vessel in rat cornea by using transmission electron microscope assay.Result :1.Neither LYVE-1-positive vessels nor CD34-positive vessels were detected in normal rat cornea. Both LYVE-1-positive vessels and CD34-positive vessels were detected in rat cornea 3 days after alkaline burn. The LYVE-1-positive-vessel counting reached the peak 14 days after injury, and gradually decreased at day 28 after alkaline burn.2.Under electron microscopy, the lymphatic vessels in the rat injured corneas were detectable 14 days after injury in the vascularized rat cornea. Corneal lymphatic vessel had its structure features such as thin endothelial cell,without erythrocytes in the lumen or pericytes,and abcent continuous basement membrane. No lymphatic vessels was oberved in the control group..3. The expression of VEGF-C in rat cornea was faintly detected in the basal layers of the corneal epithelium before alkaline burn and it was up-graduated 1 day after injury ,reached the peak 5 days after alkaline burn.VEGF-C predominantly expressed in the endochylema of epithelial, inflammatory cells, some keratocytes and new vessels in rat cornea. The expression level of VEGF-C was minimanly detected 28 days after alkaline burn which was no different from the control group (P>0.05).4.The expression of VEGFR-3 in rat cornea was minimally detected in the basal layers of the corneal epithelium before alkaline burn and it was up-graduated 3 days after alkaline burn, reached the peak 5 days after alkaline burn. VEGFR-3 predominantly expressed in the corneal new lymphatic vessel walls.After 5 days, it gradually decreased, until day 28 , but the level of expression was still higher than the control goup.(P<0.05).5.There was an obvious positive correlation between the expression of VEGF-C and LVC(lymphatic vessels counting)(rs=0.435, P<0.001). And so was the expression of VEGFR-3 and LVC (rs=0.589, P<0.001).Conclusion:1.There were new lymphatic vessels in the vascularized rat cornea after alkaline burn.2.VEGF-C and VEGFR-3 might be a couple of important regulative factors in corneal lymphangiogenesis after alkali burn.