On the Misuse of Virus-Transformed Human Corneal Epithelial Cells as Surrogates for Normal Cells.

Research in corneal biology and pathology including disease modeling and drug testing largely depends on the availability of human ex vivo cultures. Because normal corneal epithelium can be cultured only for several passages, stable epithelial cell lines transformed by different agents or spontaneously have been developed. Telomerase immortalized diploid cell lines introduced more recently were shown to recapitulate traits of normal cells including the expression of some markers and stratification ability. At the same time, there are frequently used cell lines generated by transformation with viruses. The most popular lines were shown to be unstable, tetraploid, lacking important epithelial markers, having aberrant differentiation and deviating from normal cells by gene expression patterns. This perspective reviews properties of various corneal epithelial cell lines and cautions against the use of virally transformed, especially tumorigenic cell lines, as seriously deviating form normal cells. We also provide commercial sources of normal corneal cells and briefly discuss possible future use of limbal organoids.