Effect of human amniotic membrane extract in corneal epithelial wound healing

This study was performed in the Firat University Medical School Department of Ophthalmology. The purpose of this study was to determine the therapeutic eff ect of topical administiration of amniotic membrane extract, serum and amniotic membrane transplantation in rabbit cornea that was exposed to alkali burn. Twentyfour rabbit weighing 2500 - 3000 g were enrolled in the study and they were randomly distributed into 8 groups. A central corneal epithelial wound extending into the stroma was produced by using 1 N NaOH soaked filter-paper disc (8 mm diameter) applied to the corneal surface for 30 seconds in group 1, 2, 3, 4. In group 1 and 5 topical amniotic membrane extract, in group II and VI topical serum, in group III and VII amniotic membrane transplantation and in group IV and VIII no treatment was administered with the same protocol. The wound size was photographed by staining the cornea with fluorescein at 2, 6 and 8. days. By using computer imaging analysis the area of the wound was measured from the photographs (Topcon, Itabashiku, Tokyo, Japan). At the 8 th day, the animals were sacrificed and corneas were excised. Half of the corneas were reserved for histopathological evaluation, the other half for biochemical analysis in each group. The EGF levels were determined by ELİSA in amniotic extracts and serum and in corneal lysates. The corneas were stained by H&E and corneal neovascularization, PMNL numbers were counted and central cornea epithelial thickness was measured by light microscope. The results were compared statistically. In group 4 reepithelialization was statistically faster than the other epithelial defect performed groups (group 1, 2, 3). The low rate of reepithelialization in group 1, 2 and 3 was due to antigenic properties of heterologous treatment. In histopathologic analysis of each group indicated that the number of PMNL s and neovascularization were statistically lower and central corneal epithelium was thicker in amnion membrane transplant treatment group (group 3) than amniotic extract, serum and no treatment groups. Biochemical analysis of each group indicated that ocular surface trauma such as surg ery, increased the EGF levels due to upregulation of EGFR. But excess EGF levels due to exogenous administration caused EGFR downregulation and degradati on so this is the possible explanation of the lower values of EGF levels in group 1 (amnion extract) than the other s. Our results suggested that that amniotic membrane transplantation is more successful in preventing corneal inflammation, neovascularizatio n than amniotic extract and serum treatment in experimental alkali wound. In no treatment group, corneal reepithelialization rate was better than the heterologous treatment groups. We concluded that high dose of EGF may delay reepithelialization by triggering inflammation and EGFR downregulation. We advise amniotic membrane transplant ation in persistent epithelial defect treatment because of its remodeling effect although it does not fasten the reepithelialization rate. Key Words: Experimental alkali wound, amnion membrane transplantation, auotologous serum treatment, EGF