Abstract
Abstract: :
Purpose:To determine whether cells expressing high levels of ß1 integrin in the human corneal limbal stem cell compartment simultaneously express high levels of E-cadherin. In addition, to determine whether other integrins and / or cell surface proteins might provide additional ways to identify the corneal limbal stem cells. Methods:Human corneal donor rims were obtained from corneal transplant surgery. The tissue was prepared for cross section and whole mount analysis. For whole mount analysis the tissue was incubated in 2% Dispase II (1 hr) and the epithelial layer was gently removed from the underlying tissue as an intact sheet and fixed immediately in 4% paraformaldehyde for 2 hrs at room temperature. Cross sections of the corneal limbal region were prepared from cryo-embedded tissues. The whole mounts and tissue sections were stained with ß1 and E-cadherin or α6 and E-cadherin as well as other antibodies. Confocal microscopy was used to detect and analyze staining patterns. Results:The limbal region where stem cells are believed to reside was found to have increased staining of ß1 integrin while the region thought to represent transient amplifying cells was found to have increased staining of α6 integrin (Yiu et al, Invest Ophthalmol Vis Sci; 2001, 5477, vol. 42(4)). We have confirmed these findings. In addition, we have found that E-cadherin co-localized to the same cells that were stained brightly with ß1 integrin. This is in contrary to findings in epidermal stem cells (Moles et al, J. Histochem. Cytochem. 45: 867-874). Conclusion:Our results demonstrate that the corneal limbal stem cells have characteristics similar to skin epidermal stems in high expression of ß1 integrin. However, the simultaneous expression of high level of E-cadherin differs from epidermal stem cells. Double labeling of corneal stem cells may give greater recognition of stem cells than ß1 integrins alone.
Keywords: 372 cornea: epithelium • 370 cornea: basic science