Generating minicorneal organoids from human induced pluripotent stem cells.

Corneal epithelial stem cells residing within the annular limbal crypts regulate adult tissue homeostasis. Autologous limbal grafts and tissue-engineered corneal epithelial cell sheets have been widely used in the treatment of various ocular surface defects. In the case of bilateral limbal defects, pluripotent stem cell (PSC)-derived corneal epithelial cells are now being explored as an alternative to allogeneic limbal grafts. Here, we report an efficient method to generate complex three-dimensional corneal organoids from human PSCs. The eye field primordial clusters that emerged from differentiating PSCs developed into whole eyeball-like, self-organized, three-dimensional, miniature structures consisting of retinal primordia, corneal primordia, a primitive eyelid-like outer covering and ciliary margin zone-like adnexal tissues in a stepwise maturation process within 15 weeks. These minicorneal organoids recapitulate the early developmental events in vitro and display similar anatomical features and marker expression profiles to adult corneal tissues. They offer an alternative tissue source for regenerating different layers of the cornea and eliminate the need for complicated cell enrichment procedures.