Safety and preliminary efficacy of human adipose tissue mesenchymal stem cells (hAT-MSC) to restore the ocular surface in an in vivo experimental model of limbal stem cell deficiency (LSCD)

Abstract

Purpose: In order to restore the ocular surface in cases of limbal stem cell deficiency (LSCD) an extraocular source of stem cells is needed to avoid dependence on limbal stem cells which are difficult to isolate and culture. There is evidence indicating that mesenchymal stem cells (MSC) could play a beneficial role in the restoration of the ocular surface in LSCD. The aim of this work was to test safety and preliminary efficacy of human adipose tissue MSC (hAT-MSC) to regenerate the ocular surface in a model of partial LSCD developed in rabbits.

Methods: After corneal epithelial debridement, a surgical 180° limbal peritomy was performed in 12 rabbits. After 3 weeks, hAT-MSCs, labeled with bromodeoxyuridine (BrdU) and seeded onto amniotic membrane, were transplanted onto the ocular surface of 6 rabbits. Corneal neovascularization, opacification and epithelial defects were clinically scored by two different researchers on a weekly basis. Histopathology analyses at the end of the follow-up (11 weeks) evaluated the presence of inflammation and goblet cells (as a sign of conjunctival in-growth) in the limbus and central cornea. Immunofluorescence studies were done to locate hAT-MSC (BrdU) and to analyze the expression of the corneal (CK3, E-cadherin) and limbal (CK15, p63) epithelial cell specific markers.

Results: None of the clinical signs were aggravated after hAT-MSC transplantation. Although histological differences were not found in the transplanted eyes in comparison with the nontransplanted eyes (presence of inflammation and some goblet cells in the limbus), epithelial defects significantly decreased 3 weeks after transplantation. hAT-MSC labeled with BrdU were located in inflamed areas of limbal stroma, while corneal and limbal epithelial phenotypes (expression of CK3 and E-cadherin in the cornea, and CK15 and p63 in the limbus) were partially restored.

Conclusions: Although a model of total LSCD is necessary to test the efficacy of hAT-MSC to restore the ocular surface of patients suffering from LSCD, our results demonstrate that hAT-MSC are safe, migrate to inflamed areas of the ocular surface, and partially restore corneal epithelial phenotype.

Keywords: 482 cornea: epithelium • 721 stem cells