Enrichment of Corneal Epithelial Progenitor/Stem Cells Using Cell Surface Marker Alpha 6 Integrin and CD71

Abstract

Purpose: : In murine and human epidermis, epidermal progenitor/stem cells are enriched in the alpha 6 integrin^bri/CD71^dim fraction separated by cell sorting. The purpose of this study was to examine whether the cell surface marker alpha 6 integrin and CD71 can be used to select corneal epithelial progenitor/stem cells.

Methods: : Human corneoscleral rims from USA eye bank eyes were used. Epithelial cells were isolated from the limbus and central cornea, and flow cytometric analysis for alpha 6 integrin and CD71 was performed. Epithelial cells were separated to each subpopulation by cell sorting, and then subjected to colony–forming assay (CFA). The expression patterns of alpha 6 integrin and CD71 in limbal epithelium and the corneal epithelium were also investigated by immunofluorescence staining.

Results: : The subpopulation of alpha 6 integrin positive (alpha 6 integrin^posi)/CD71 negative (CD71^neg) cells were detected in the limbal epithelium, but not in the corneal epithelium. CFA showed that the alpha 6 integrin^posi/CD71^neg cells exhibited higher colony–forming efficiency than other cell populations. Immunofluorescence staining revealed that alpha 6 integrin was expressed throughout by the basal epithelial cells, while CD71 was expressed abundantly in corneal epithelium.

Conclusions: : Alpha 6 integrin and CD71 may serve as useful cell surface markers in the enrichment of corneal epithelial progenitor/stem cells.

Keywords: flow cytometry • cornea: epithelium • regeneration