Purpose: To isolate precursors of human corneal stromal and endothelial cells in vitro and to compare the distribution of rabbit corneal endothelial cell precursors in the central and peripheral regions of the cornea.
Methods: Sphere-forming cells were isolated from human corneal stromal and endothelial cells by a reaggregation-free neurosphere assay. To promote differentiation of the cells, the isolated sphere colonies were plated in wells with a medium containing fetal bovine serum. Expression of various proteins was examined in the sphere colonies and their progeny by immunocytochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR). Corneal endothelium and Descemet membrane of rabbits were demarcated into peripheral (6.0-10.0 mm in diameter) and central (6.0 mm in diameter) regions. Precursor cells were isolated from these 2 regions by sphere-forming assay, and the number of sphere colonies and size of spheres were compared in the central and peripheral regions.
Results: Human corneal stromal and endothelial cells formed sphere-shaped colonies that expressed mesenchymal and neural markers. The rate of sphere formation in the peripheral region of rabbit corneal endothelium was significantly higher than that in the central cornea.
Conclusion: Adult human corneal stroma contains precursor cells that have a strong propensity to differentiate into mesenchymal fibroblasts, but these cells can also differentiate into neuronal lineage. Adult human corneal endothelium contains precursors with a propensity to differentiate into corneal endothelial cells, but these cells can also produce neuronal and mesenchymal cell proteins. The peripheral endothelium of rabbit cornea contains more precursors than the central region.