High-resolution promoter map of human limbal epithelial cells cultured with keratinocyte growth factor and rho kinase inhibitor.

An in vitro model of corneal epithelial cells (CECs) has been developed to study and treat corneal disorders. Nevertheless, conventional CEC culture supplemented with epidermal growth factor (EGF) results in a loss of CEC characteristics. It has recently been reported that limbal epithelial cells (LECs) cultured with keratinocyte growth factor (KGF) and the rho kinase inhibitor Y-27632 could maintain the expression of several CEC-specific markers. However, the molecular mechanism underlying the effect of culture media on LECs remains to be elucidated. To elucidate this mechanism, we performed comprehensive gene expression analysis of human LECs cultured with EGF or KGF/Y-27632, by cap analysis of gene expression (CAGE). Here, we found that LECs cultured with KGF and Y-27632 presented a gene expression profile highly similar to that of CECs in vivo. In contrast, LECs cultured with EGF lost the characteristic CEC gene expression profile. We further discovered that CEC-specific PAX6 promoters are highly activated in LECs cultured with KGF and Y-27632. Our results provide strong evidence that LECs cultured with KGF and Y-27632 would be an improved in vitro model in the context of gene expression. These findings will accelerate basic studies of CECs and clinical applications in regenerative medicine.