Retinoic acid engineered amniotic membrane used as a graft or homogenates: a comparative study of their positive effects on corneal alkali burns

Abstract

Purpose : Alkali burns are the most common and the most dreaded chemical ocular injuries with a functional prognosis depending on corneal wound healing efficiency. The purpose of our study is to compare amniotic membrane (AM), previously treated or not by all-trans retinoic acid (atRA), used as graft and homogenates and their benefits on wound healing.

Methods : All the experiments were conducted in accordance with the ARVO Resolution for the Use of Animals in Ophthalmic and Vision Research and approved by our regional ethic committee (CEMEA Auvergne). Fifty male CD1 mice, with reproducible corneal chemical burn (protocol), were divided into five groups: group 1 treated with saline solution, groups 2 and 3 with AM graft untreated or treated in advance by atRA respectively, groups 4 and 5 with homogenates of AM untreated or treated in advance before by atRA respectively. After 7 days of treatment, measures of ulcer area and depth were realised as well as VEGF and MMP-9 quantification. Statistical analyses were conducted using non parametric test (kruskal-wallis and Mann-whitney U-test) after a test for normality of data using a Shapiro-Wilk test.

Results : AM induction by atRA was confirmed by quantification of RARß, a well-established retinoic induced gene. A significant improvement of corneal wound healing on ulcer area and depth with both used amniotic membranes strategies was obtained. This positive action was increased when amniotic membrane was pre-treated by atRA. No major differences were found between homogenate and AM grafts efficiency. AM also induces a decrease of VEGF and MMP-9 levels during the wound healing process. Furthermore, the atRA treatment of membrane leads to an even more decrease of both proteins expression.

Conclusions : Amnion homogenate is as effective as AM graft in promoting corneal wound healing in mouse model. Higher positive effect of AM on wound healing was obtained with an atRA treatment underlying a synergic effect of AM and retinoids. Our results give us hope to propose at term new therapeutic strategy applied to cornea wound healing.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.