Abstract
Abstract: :
Purpose: To determine the differentiation potential of TERT-immortalized human conjunctival and corneal epithelial cell lines designated Conj Ep-1/P/C/TERT. Methods: The cell line was cultured on (1) three substrates (plastic, Biocoat cell culture inserts coated with type I collagen, and Biocoat inserts coated with matrigel); and (2) on uncoated cell culture inserts with corneal fibroblasts in the culture dish. For comparison, cells cultured on plastic were used as baseline. Cells were also injected subcutaneously into the flank or nape of the neck of SCID mice. Cultures were analyzed by routine light microscopy, by immunohistochemistry with an antibody to the goblet cell-specific mucin MUC5AC, and by real-time RT-PCR for expression of the mucin genes, MUC1, MUC4 and MUC5AC. Results: When cultured on plastic and type I collagen, the cells stratified to 2-3 cell layers, with islands having additional cell layers. On matrigel, the cells formed spherical cysts within the matrix, with 2-3 cell layered walls surrounding a central matrigel-filled lumen. On type I collagen, a small subpopulation of cells bound antibodies to MUC5AC. In SCID mice, the cell line formed hollow cysts that had 2-3 cell layered walls surrounding lumens. Culture on collagen did not affect MUC1 expression, but culture on matrigel downregulated the membrane-spanning mucin. MUC4 expression was downregulated by culture on both collagen and matrigel. Culture on type I collagen upregulated MUC5AC expression. This data is consistent with the immunolocalization data showing MUC5AC localization in a subpopulation of cells grown on collagen. Coculture with fibroblasts also upregulated MUC5AC mRNA. Conclusion: Since the conjunctival cell line responds to extracellular matrix and fibroblasts by expressing the goblet cell mucin MUC5AC in a subpopulation of cells, it does appear to have the capability of differentiating and expressing apical cell- and goblet cell-specific mucins. The cell line will be a valuable tool to determine tissue-specific regulation of the mucin genes expressed by the ocular surface epithelia and to determine factors regulating goblet cell differentiation.
Keywords: 365 conjunctiva • 375 cornea: surface mucins • 376 cornea: tears/tear film/dry eye