The Hippo/YAP Pathway Mediates the De-differentiation of Corneal Epithelial Cells into Functional Limbal Epithelial Stem Cells In Vivo

Regeneration after tissues injury is often associated with cell fate plasticity, which restores damaged or lost cells. The de-differentiation of corneal epithelial cells (CECs) into functional stem cells after the ablation of innate stem cells, known as limbal epithelial stem cells (LESCs), remains controversial. In this study, we showed the functional maintenance of corneal epithelium after the ablation of innate stem cells, and the regeneration of functional LESCs, which maintained corneal transparency, prevented corneal conjunctivalization and participated in the wound healing. Subsequent intravital lineage tracing revealed that CECs could de-differentiate into active or quiescent LESCs, which functioned as well as their innate counterparts. Furthermore, the de-differentiation of CECs required an intact limbal niche, and the outcome of the competition between conjunctival and corneal epithelium for the limbal niche determined whether the de-differentiation would occur or not. Mechanically, the suppression of YAP signal promoted the de-differentiation of CECs after the ablation of innate stem cells, while the persistent activation of YAP prevented the de-differentiation of CECs after an additional alkali burn to the limbal stroma. These results will pave the way for an alternative approach to treat limbal stem cell deficiency (LSCD) by modulating the de-differentiation of CECs in vivo.