In situ distribution of markers for stemness, quiescence, proliferation and differentiation in the human cornea and limbus

Abstract

Aims/Purpose: Identify the distribution of the most commonly used markers for stemness, quiescence, proliferation, and differentiation in limbal compartments such as human limbal epithelial crypts, posterior and anterior limbus, as well as the central and posterior cornea.Methods: Corneal‐limbal biopsies from cadaver human donors (n = 3) embedded in paraffin were proceeded for immunohistochemistry fluorescence and examined for stemness/progenitor markers (p63α, SOX9, ABCG2, N‐cadherin), proliferation markers (ki‐67), quiescence marker (CEBPD), differentiation markers (CX43, KRT3, KRT12, KRT13), and epithelial marker (E‐cadherin). Images were obtained by Zeiss Axio Observer. Fluorescent images were obtained using the Zeiss Axio Imager M1 fluorescence microscope (ZEISS, Oberkochen, Germany).Results: The stemness/progenitor markers p63α and SOX9 were found in basal and suprabasal cells of limbal epithelial crypts and limbal epithelium, whereas the ABCG2 and N‐cadherin were exclusive for limbal basal epithelium in all limbal structures. Proliferation marker Ki‐67 was most abundant in suprabasal layers of the limbus and rarely found in the posterior cornea, while absent in anterior cornea. Quiescence marker CEBPD was positive in the basal cells of both, limbus and cornea. Differentiation markers KRT3 and KRT12 were positive in the whole cornea and intermediate and superficial layers in anterior and posterior limbus, while rarely present in limbal epithelial crypts. However, CX43 was staining almost all suprabasal layers in the limbus as well as basal and suprabasal layers in the cornea. KRT13 was exclusive for superficial layer of the anterior and posterior limbus layers staining conjunctival cells.Conclusions: Here we identify the localization of the most common markers used to determine the stemness, quiescence, proliferation, and differentiation status to unravel the in situ distribution of these markers in the limbal epithelial crypts, posterior and anterior limbus, as well as the central and posterior cornea. The study accumulated new knowledge about the distribution of these markers and the corneal‐limbal organization.