Abstract

Corneal stem cells (SCs) are located at the sclerocorneal limbus in the palisades of Vogt, which are highly pigmented structures with an abundance of melanocytes, antigen-presenting cells, and lymphocytes [1,2]. These cells, termed limbal epithelial crypts (LECs), are situated in an anatomi-cally defined site of the human limbus called the “niche ” [1,3]. The absence of a definitive biological or phenotypic marker contributes a degree of uncertainty related to the unequivocal isolation and characterization of limbal stem cells [3,4]. So far, a variety of SC markers have been proposed to identify this population of cells [4]. Among the major characteristics proposed for SCs are the following: small size, slow-cycling properties, expression of transporters (such as ABCG2, Na/K-ATPase, glucose transporter I), a transcription factor (p63), integrins (α9, β1, and β4), cytokeratin (K5/K14), cell cycle