Integrins in slow cycling corneal epithelial cells at the limbus in the mouse

¹ The George Washington University Medical Center, Washington, DC

^* To whom correspondence should be addressed. E-mail: mastepp{at}gwu.edu.

	Abstract

Adult corneal epithelial stem cells (CESCs) have been shown to reside at the periphery of the cornea at a site called the corneoscleral junction or limbus. While studies have shown that these cells are slow cycling, their molecular characteristics are not well understood. Using a whole mount procedure, we show that while 9 integrin is present in a subset of the basal cells at the corneal limbus and absent in the central cornea, 1, 4, 3, and 6 integrins are more highly expressed overall in central corneal basal cells. To characterize CESCs based on their slow-cycling nature, we simultaneously evaluated 5Bromo-2-deoxy-uridine (BrdU) label-retaining cells (LRCs) and integrin expression (9, 1 and 4) in a total of 1889 cells at the limbus of adult mice that had been injected as neonates with BrdU. While the LRCs were usually observed adjacent to 9 integrin positive cells, most LRCs were 9 integrin negative and expressed high levels of 1 and 4 integrins. In addition, we observed more BrdU-positive LRCs at the superior and inferior quadrants of adult mouse corneas than at the nasal and temporal quadrants, and determined that 0.94 to 3.6% of the limbal basal cells were slow-cycling. We conclude from these data that the slow cycling LRCs in the adult mouse cornea are enriched in cells that express high levels of 1 and 4 integrins and little 9 integrin.

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