NYU Langone Medical Center

Epithelial Keratins and Stem Cells

Based on the unique keratin expression pattern of corneal epithelium, we proposed in 1986 that corneal epithelial stem cells reside in the limbus, a previously ignored, transitional zone between cornea and conjunctiva (J Cell Biol 1986). This work and a subsequent 1989 Cell paper done in collaboration with Robert Lavker of the Northwestern University led to the rejection of the previous concept of “conjunctival epithelial transdifferentiation” which proposes that conjunctival epithelial cells can migrate onto the cornea proper forming a bona fide corneal epithelium. The limbal stem cell concept explains why an earlier surgical procedure, in which conjunctival epithelium was used to repair damaged corneal epithelium, was ineffective. This concept led to the introduction of a new surgical procedure called “limbal transplantation” in which limbal stem cells are used to repair a damaged or denuded corneal epithelium. Without limbal stem cell transplantation, corneal transplants in patients who are deficient in limbal stem cells invariably fail due to blood vessel in-growth and corneal opacity. Limbal stem cell transplantation can solve this problem and restore the eyesight of many patients; this procedure is therefore being performed by ophthalmologists worldwide. In addition, the limbal stem cell concept has led to an improved understanding and classification of various anterior ocularepithelial disorders. The limbal stem cell concept is now widely accepted and is included in most ophthalmology textbooks.

View Slideshow