Limbal stem cell deficiency: special focus on tracking limbal stem cells

Abstract

The cornea, the transparent part of the eye that helps in the formation of images, has multiple layers. Among them, the superficial epithelial layer is protected and maintained homeostatically by the limbus, located in the periphery of the cornea. Limbal stem cells are located at the basal layer of the limbus and the loss of these cells is called limbal stem cell deficiency (LSCD). LSCD is characterized by corneal vascularization, inflammation, and conjunctivalization, which ultimately lead to blindness. Several clinical transplantation procedures used for the treatment of LSCD are cultivated limbal epithelial transplantation, simple limbal epithelial transplantation, and cultured oral mucosal epithelial transplantation. Long term follow-up of these mentioned transplantations across the globe shows that the success rate declines as the follow-up period increases. There is an urgent need to know the mechanism of stem cell transplantation in curing LSCD to improve the success rate of the transplantations. There are numerous reports on other stem cell transplantation procedures and its mechanism in healing the disease or deficiency. In the case of LSCD a lot of labeling and tracking methods are used, but there are no confined reports on the mechanisms of the stem cell transplantation and its success. This review summarizes the current treatments available for LSCD, substrates used during limbal stem cell culture and transplantation, and findings from posttransplant cell tracking experiments conducted up to date.