Abstract
Purpose: :
The ocular surface is covered by 2 biologically distinct epithelia, the corneal– and the conjunctival epithelium; the expression of keratin12 is currently considered a hallmark of cornea–type differentiation. Here we report the biological features of keratin12–positive cells in human bulbar conjunctival epithelium.
Methods: :
Human conjunctival tissues were subjected to investigate the keratin12 positive cells in conjunctiva by immunostaining, in situ hybridization, western blotting, RT–PCR, and FACS. Gene expression profiling of these cells was carried out with iAFLP. To determine the presence of stem– or progenitor cells, immunostaining and colony–forming assay were performed.
Results: :
Western blotting, RT–PCR revealed that K12 was expressed in conjunctival epithelium. Immunostaining analysis showed that K12 positive cells reside mainly in clusters in conjunctival epithelium. FACS analysis showed that 0.2–1.7% of conjunctival epithelial cells collected from the inferior bulbar conjunctiva were keratin12–positive. iAFLP analysis revealed that gene expression patterns of these cells were highly similar to that of corneal epithelial cells. p63 and ABCG2 were expressed beneath the keratin12–positive cells. Some colony–forming cells expressed keratin12.
Conclusions: :
The keratin12–positive cells appear to be ectopically–residing, self–maintaining corneal epithelial cells in the conjunctival epithelium.
Keywords: cornea: epithelium • conjunctiva • gene/expression