Enrichment of corneal epithelial stem/progenitor cells using cell surface markers, integrin α6 and CD71

Corneal epithelial stem cells are believed to reside in the basal layer of the limbal epithelium, but no definitive cell surface markers have been identified. For keratinocytes, stem/progenitor cells are known to be enriched by cell surface markers, integrin α6 and CD71, as a minor subpopulation which shows high integrin α6 and low CD71 expressions (α6bri/CD71dim). In the present study, we investigated the possibility that corneal epithelial stem cells can be enriched by integrin α6 and CD71. The α6bri/CD71dim cells were separated by fluorescence-activated cell sorting, as a minor subpopulation of the limbal epithelial cells. They were enriched for relatively small cells, showing a higher clonogenic capacity and expression of stem cell markers, but a lower expression of differentiation markers, compared to other cell populations. The cells were localized immunohistochemically in the basal region of the limbal epithelium. These results indicate that the α6bri/CD71dim subpopulation enriched corneal epithelial stem cells.