The Functions Of MMP-2 And TIMP-2 In The Corneal Alkaline Burn With Amniotic Membrane Transplantation In Rabbit

PURPOSES: To investigate the effect of amniotic membrane transplantation (AMT) for corneal alkali bum in rabbit, and the expression of MMP-2 and TIMP-2 during the course of corneal alkaline bum with AMT and without AMT, in order to explore the potential roles of MMP-2 and TIMP-2 during the course of corneal alkaline bum with AMT in rabbit.METHODS: Sixty New Zealand white rabbits were used and randomly divided into four groups: Normal cornea only as the control group (C), the corneal alkaline burn group (A), the fresh amniotic membrane transplantation group (fAMT), and the preserved amniotic membrane transplantation group (pAMT). Corneal alkaline bum models of the experimental groups were made. AMT was performed 30 minutes after corneal alkaline burn. The corneas were immunohistochemically analyzed with antibodies directed against MMP-2 and TIMP-2, and pathohistology and computerized corneal analysis were studied on day 14, 30, and 60.RESULTS:1. Compared with rabbits from A, epithelium healing, corneal inflammation, neovascularization and scarring were all markedly improved in AMT after injure, and fAMT was better for treatment than pAMT.2. MMP-2 and TIMP-2 immunoreactivities were expressed in the normal corneas, predominantly in the corneal epithelium. After injury, immunoreactivities of both MMP-2 and TIMP-2 were increased notably in the healing corneal epithelium, infiltrating inflammatory cells, stromal fibroblasts and ingrowing vascular endothelial cells.3. The expression of MMP-2 was lower in the corneal burn with AMT than that in the A, the expression of TIMP-2 in the AMT groups was near to that in A, and the ratio of MMP-2/TIMP-2 was notably decreased in AMT groups compared with that in A on the 14th, 30th day after injure. The expressions of MMP-2 and TIMP-2 were both higher than those in C at the same time. Compared with the rabbits from pAMT, the expression of MMP-2 was decreased, the expression of TIMP-2 was increased, and the ratio of MMP-2/TIMP-2 was notably decreased in fAMT on the 14th, 30th day after injure.4. The changes of MMP-2 and TIMP-2 were paralleled the corneal pathohistological process.CONCLUSION: AMT played a key role in regulating the biological expression of MMP-2 and TIMP-2, and then maintaining the balance between corneal ECM deposition and its degradation. Compared with pAMT, fAMT has stronger effect on promoting corneal wound healing, inhibiting inflammation and neovascularization processes of corneal alkaline burn.