Porcine Corneal Epithelial Cells Consist of High- and Low-Integrin β1–Expressing Populations

PURPOSE: Immunohistochemically, all cells in the porcine corneal epithelium, from the superficial to the basal layer, express integrin beta1. Flow cytometric study has shown that they comprise integrin beta1 high-expressing (beta1 2+) and low-expressing (beta1+) populations. This study was undertaken to determine their proliferation characteristics. METHODS: Epithelial cells from porcine corneas were sorted and labeled with anti-integrin beta1 antibody and a fluorescent-dye-conjugated secondary antibody. The fluorescent intensity of labeled cells was analyzed and beta1 2+ and beta1+ cells were cultured in an adhesive-coated culture plate. RESULTS: Flow cytometry demonstrated that the epithelial cells comprised two distinct populations with a similar ratio throughout the cornea. Whereas beta1 2+ cells attached and grew to confluence in the plate, beta1+ attached only transiently to the plate and exhibited minimal growth. CONCLUSIONS: The data indicate that the porcine cornea contains two distinct populations of epithelial cells, one exhibiting high and the other low integrin beta1 expression. The observation that beta1 2+ cells had greater growth potential suggests that they may represent an enriched population of transit-amplifying cells.