Expression of laminin-5 with amniotic membrane transplantation in excimer laser ablated rat corneas

PURPOSE: To investigate the expression of laminin-5 during epithelial healing and evaluate its expression in vivo using rat corneas on which amniotic membrane was applied to cover the wound after excimer laser photoablation. SETTING: Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. METHODS: Myopic photorefractive keratectomy (PRK) with a 100 microm deep ablation was performed in Sprague Dawley rats killed 6, 12, 24, 48, 72, and 96 hours after the procedure. In the first group of 30 rats, the excimer laser-ablated cornea was covered with amniotic membrane after PRK. Thirty other rats in which no amniotic membrane treatment was used served as controls. Immunohistochemical and immunofluoresce in techniques were used to monitor the expression of laminin-5, gamma2, and gamma1 in the rat corneas. Immunoblotting was used to compare the expression of laminin between the amniotic membrane group and the control group. RESULTS: In the immunoblotting study, laminin-5, alpha3, and gamma2 increased 24 hours after amniotic membrane treatment compared to the control group. At 12 hours, in vivo immunostaining of the corneas in both groups expressed laminin, but laminin-5 and gamma2 were more intensely expressed in the amniotic membrane group. This continued until reepithelialization. Expression of the gamma1 chain was not different between the 2 groups. CONCLUSION: With the use of amniotic membrane, the expression of laminin-5 and gamma2 was faster and more intense than in a control group during reepithelialization of excimer laser-ablated rat corneas.