Abstract
Purpose: :
Transparency is the key characteristic of a functional cornea and a warrant for visual acuity. Corneal endothelium (CE) is the pivotal layer to maintain corneal transparency. Loss of CE cells ultimately leads to blindness necessitating corneal transplantation. With lamellar grafting techniques spreading over the globe, engineering CE cell sheets seems rational. However, in-depth knowledge of cells with precursor or stem cell-like properties for CE cells and the exact anatomical locations of those cells are not clearly identified yet. As these progenitor cells might serve the basis for tissue engineering approaches, to create functional CE we systematically studied the distribution and localization of cells with stem-cell (SC) characteristics and in particular mesenchymal SC (MSC) characteristics in human and mouse CE and the anterior chamber.
Methods: :
To conclusively study the distribution of putative MSC in the anterior chamber and in the cornea, typical MSC marker proteins (CD44, CD73, CD90, CD105,stro-1) were examined in sections of eyes, corneas and whole mount staining of CE cells obtained from C57BL6 and Balb/C mice and human tissue by immunohisto- and immunocytochemistry.
Results: :
Among cell surface factors studied so far CD44 expression was identified in single cells located in the peripheral part of lens epithelium in eye sections as well as in single cells located in the peripheral parts of CE and in the limbus, but not in central parts of cornea. Moreover, CD44 could be detected at cell borders of specific cell clusters throughout the endothelium (7%). CD 73, CD90, CD 105 and stro-1 expression was low or not detectable.
Conclusions: :
Our results identify to our knowledge for the first time CD44+ cells with potential stem cell properties in distinct anatomical localization such as the peripheral part of the CE and the limbus. These findings suggest that peripheral corneal tissue might be a promising source of future tissue engineering approaches for corneal endothelium.
Keywords: cornea: endothelium • immunohistochemistry