Therapeutic Potential of Bone Marrow Mesenchymal Stem Cells in Corneal Chemical Burns: An in vitro and in vivo Study

Abstract

Purpose: : Alkali burn injuries of the ocular surface are potentially blinding conditions in which cornea loses its transparency and avascularity. The purpose of this study was to investigate the therapeutic potential of mesenchymal stem cells (MSCs) in corneal wound healing.

Methods: : Green florescent protein labelled MSCs and telomerase immortalized corneal epithelial cells (HCLE) were co-cultured and MSC phenotype was evaluated. Cytokeratins, beta-catenin and E-cadherin were detected by immunohistochemistry fluorescent staining. Green fluorescent protein (GFP) and telomerase staining were used to distinguish MSC and HCLE. Additionally, we investigated the therapeutic potential of MSC sub-conjunctival injection in a rat ocular surface alkali burn model. Transparency and corneal neovascularisation were evaluated by slit lamp observation, Hematoxylin and Eosin staining and immunofluorescent staining

Results: : After 7 days in the GFP-MSC and HCLE co-culture, a subpopulation of GFP positive cells displayed a cobblestone appearance. While MSC did express neither cytokeratin nor E-cadherin, these epithelial cell markers and cell surface expression of beta-catenin were detected in a subpopulation of GFP-MSC in co-culture with HCLE. Some GFP-MSC with double nuclei where also detected, in these cells, telomerase staining was positive in only one nucleus suggesting that MSC-HCLE cell fusion was responsible for this phenomenon. In in vivo experiments, slit lamp observation, HE staining and immunofluorescent staining showed that the rats receiving sub-conjunctival injection of MSC improved transparency and displayed decreased neovascularization. GFP positive cells were detectable in the conjunctiva at the site of injection after one month.

Conclusions: : During culture, some MSC can differentiate into epithelial-like cells. This was at list in part linked to cell fusion between MSC and HCLE. In vivo, sub-conjunctival injection of MSC improved the prognosis of ocular surface alkali burn injury with increased transparency and decreased neovascularization. MSC therapy appears promising in the management of ocular chemical burns. Further investigations of the mechanisms involved in this clinical improvement are needed.

Keywords: wound healing • differentiation • plasticity