[Differing regulation of proliferation of limbus and corneal epithelium caused by serum factors].

The basal limbal epithelium contains corneal stem cells, which are responsible for the maintenance of the corneal epithelial mass. In our study of the regulation of limbal progenitor cells, we investigated the proliferation of limbal and corneal epithelial cells in a defined single-cell clonal culture system. In a serum-free defined medium the limbal epithelium generated significantly fewer colonies than the cornea, which also proliferated more slowly. The addition of fetal calf serum resulted in the stimulation of a unique subpopulation of progenitor cells at the limbus. In contrast, proliferation of the peripheral corneal epithelium was inhibited by serum. These results further support the concept of a limbal location of corneal stem cells and suggest that limbal progenitor cells might be regulated preferentially by serum factors.