Expression of the Putative Stem Cell Marker CD133 in the Human Eye

Abstract

Abstract: : Purpose: To determine expression of the putative stem cell marker CD133 in the human eye and to analyse distribution of its n– and c–terminal splice variants. Methods: Paraffin sections were obtained from three healthy human donor eyes discarded from corneal transplantation and from retinoblastoma and pterygium. Immunohistochemistry was performed using monoclonal antibody clone 293C against epitope CD133/1 and the Vectastain Elite ABC kit. Three post–mortem donor eyes were fixed in RNAlater after removal of the cornea. Ocular tissues were carefully dissected and subjected to RNA extraction. Two primer pairs were used to separate c–terminal and n–terminal splice variants and reverse transcriptase PCR was performed. Results: Immunohistochemistry revealed expression of CD133 by the epithelia of the eyelid, the excretory tracts of eyelid glands, the conjunctival and corneal epithelium, the lens epithelium and the epithelium of the iris and ciliary body. The corneal endothelium stained positive for CD133. In the posterior section of the eye, expression of CD133 was demonstrated in the retinal pigment epithelium, the retina and in the optic nerve. In pterygium, single stromal cells stained positive for CD133. PCR analysis confirmed transcription of CD133 in the conjunctiva, iris, lens, ciliary body, RPE and retina. N–terminal splice variant s1 (corresponding to isoform AC133–2) was found in the tissues of the anterior segment of the eye, whereas isoform AC133–1 was revealed in the retina and RPE. A c–terminal splice variant with a deletion of 69 bp was demonstrated in the retina and RPE. Conclusions: We have demonstrated expression of the putative stem cell marker CD133 in most ocular tissues, particularly in epithelia and other cell types with membrane protrusions. Expression of CD133 by stromal cells in pterygium was confirmed. There seems to be a differential distribution of n– and c–terminal splice variants of CD133 in the anterior and posterior section of the human eye.

Keywords: gene/expression • immunohistochemistry • Pterygium