Advisory Committee Chair
David R Whikehart
Advisory Committee Members
Dennis J Pillion
Om P Srivatava
Document Type
Thesis
Date of Award
2007
Degree Name by School
Master of Science (MS) School of Optometry
Abstract
The corneal endothelium is a layer of cells in the cornea that is responsible for maintaining the clear state of the cornea. Corneal endothelial cells may be induced to divide, but do not regularly divide in the normal cornea of a human beyond the age of twenty. Some studies have suggested that a stem cell population may reside in the pe-ripheral corneal endothelium or in the posterior limbus. Important molecular markers of stem cells are nestin which is expressed in neural crest stem cells; alkaline phosphatase is active in stem cells and not in differentiated cells; telomerase is a marker of stem cells and transient amplifying cells; and Oct-3/4 that maintains pluripotency in stem cells. Important developmental markers are Pax-6, which is expressed throughout eye development; Wnt-1 is responsible for proliferation and maintenance of stem cells; and Sox-2 maintains the adult nervous system. Wounded and unwounded whole corneas and corneal sections were analyzed by immunofluorescence for the presence of nestin, telomerase, Oct-3/4, Pax-6, Wnt-1 and Sox-2. Alkaline phosphatase activity was observed with an ELF Phosphatase Detection Kit from the American Type Culture Collection. In the unwounded cornea, nestin, alkaline phosphatase and telomerase activity was indicated in the trabecular meshwork and at Schwalbe’s line. Telomerase was pre-sent in the peripheral corneal endothelium. In the wounded cornea, nestin, alkaline phos-phatase and telomerase were observed in the same regions as in the unwounded cornea; ii however, wounding resulted in the appearance of Oct-3/4 in the trabecular meshwork, Pax-6, Wnt-1 and Sox-2 in the trabecular meshwork and at Schwalbe’s line and Pax-6 and Sox-2 in the peripheral endothelium. The data show that specific stem cell proteins are present in the trabecular mesh-work and the transition zone of the posterior limbus of unwounded corneas and, follow-ing wounding, proteins related to growth, development and differentiation appear in the posterior limbus and the corneal endothelium. These data suggest that there is a popula-tion of stem cells in the posterior limbus that may supply the corneal endothelium.
Recommended Citation
McGowan, Sara L., "Stem Cell Markers In The Posterior Limbus And Cornea" (2007). All ETDs from UAB. 3607.
https://digitalcommons.library.uab.edu/etd-collection/3607