Abstract
The cornea is essential for normal vision by maintaining transparency for light transmission. Limbal stem cells, which reside in the corneal periphery, contribute to the homeostasis of the corneal epithelium. Any damage or disease affecting the function of these cells may result in limbal stem cell deficiency (LSCD). The condition may result in both severe pain and blindness. Transplantation of ex vivo cultured cells onto the cornea is most often an effective therapeutic strategy for LSCD. The use of ex vivo cultured limbal epithelial cells (LEC), oral mucosal epithelial cells, and conjunctival epithelial cells to treat LSCD has been explored in humans. The present review focuses on the current state of knowledge of the many other cell-based therapies of LSCD that have so far exclusively been explored in animal models as there is currently no consensus on the best cell type for treating LSCD. Major findings of all these studies with special emphasis on substrates for culture and transplantation are systematically presented and discussed. Among the many potential cell types that still have not been used clinically, we conclude that two easily accessible autologous sources, epidermal stem cells and hair follicle-derived stem cells, are particularly strong candidates for future clinical trials.
Highlights
The cornea is essential for normal vision by maintaining transparency for light transmission
stem cells (SCs) onto the cornea of goats [46,47], whereas the other used fibrin scaffold in rabbits [45]. These studies demonstrated that culture and transplantation of epidermal SCs onto damaged cornea successfully restored the corneal epithelium in 100% (22/22) of the animals
The authors suggested that a possible mechanism of epidermal SCs in reconstruction of the damaged corneal epithelium involves the down-regulation of CK1/10 and up-regulation of PAX6
Summary
The cornea is the anterior, transparent, and avascular tissue with high refractive power that directs light bundles to the retina [1]. The cornea is composed of five layers, i.e., epithelium, Bowman’s membrane, stroma, Descemet’s membrane, and endothelium. The corneal epithelium plays an essential role in maintaining the cornea’s avascularity and transparency [7]. The self-renewing properties of the corneal epithelium are an important requirement for corneal integrity and function [8]. This process is dependent on a small population of limbal stem cells that are situated in the basal region of the limbus [9,10]. Limbal stem cells are presented in the basal layer of the limbal epithelium and give rise to fast-dividing, transient amplifying cells [11].
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