Abstract
Purpose: :
Damage of corneal epithelium stem cells, caused by various injuries like chemical burns or Stevens–Johnson syndrome produce a clinical entity termed limbal stem cell deficiency (LSCD). It is characterized by conjunctivalization of the corneal surface. Autologous stem cell transplantation is preferable to avoid allograft rejection. As mesenchymal stem cells (MSCs) from bone marrow are known to differentiate under very precise conditions into epithelial cells, we assessed whether MSCs could be used to treat LSCD.
Methods: :
Rabbit MSCs were isolated and expanded ex vivo. Cells were plated on denuded amniotic membrane and cultured for 15 days. Then, MSCs were labelled with iron oxide to track them in vivo. A rabbit LSCD model was used. Three weeks after corneal injury, autologous MSCs on amniotic membrane were grafted. Control rabbits were grafted with an amniotic membrane alone. After 3 weeks, histological and immunochemistry analysis of corneas were performed.
Results: :
In vitro, we differentiated bone marrow–derived cells into osteoblasts, chondroblasts and adipocytes to prove their multipotency. They were not differentiated into epithelial cells. In fact, immunochemistry against pan–cytokeratin was negative. In vivo, no neovascularization was detected on grafted corneal surfaces. In contrast, control corneal surfaces showed a peripheral neovascularisation. A multi–layer non keratinized epithelium covered the stroma after MSCs transplantation. In contrast, a pseudostratified epithelium containing several goblet cells covered the control corneal surface. Grafted cells labelled with iron oxide were inserted under the epithelium. Cytokeratin 3 used as a specific marker of corneal epithelial cells appeared to be more present in grafted corneas those in controls. P63 and cytokeratin 14 used as epithelial progenitor cell markers were expressed in almost all epithelial layers in the two tissues. Muc5Ac, specific marker for goblet cells was not detected on grafted corneas but was expressed in the periphery of control corneas.
Conclusions: :
Transplantation of MSCs improved the damaged corneal surface. MSCs therapeutic effects seem to be associated with an improvement in the corneal microenvironment rather than an epithelial differentiation.
Keywords: cornea: epithelium • wound healing