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Ocular Surface Epithelium
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 classical concept of “conjunctival epithelial
transdifferentiation” which proposes that conjunctival epithelial cells can
migrate onto the denuded cornea 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. The new 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 solved this problem and restored 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 ocular
epithelial disorders. The limbal stem cell concept is now widely accepted and
is discussed in most ophthalmology textbooks.
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