Comparison of limbal and peripheral human corneal epithelium in tissue culture

Peripheral human corneal epithelium grows better in tissue culture than central epithelium, but it is not known whether ocular limbal epithelium grows even better than does the peripheral corneal epithelium. In this work we compared the growth kinetics of limbal and peripheral human corneal epithelial cells in tissue culture. Four 1-2 mm2 explants, removed from the limbus or from peripheral cornea (1-2 mm inside the limbus) of eye bank eyes, were grown to confluence in primary culture. Cells were then passaged at 2 X 10(5) cells per dish. At intervals thereafter, the cells were counted in a hemocytometer to determine plating efficiency and growth curves. Mitotic activity was determined 4 days after passaging by labeling cultures with 3H-thymidine and counting aliquots using the hemocytometer and scintillation counter. In the primary cultures, limbal epithelium grew as small, uniformly polygonal cells. Peripheral corneal cells grew to a variety sizes. The 24 hr plating efficiency and doubling time of limbal epithelial cells were 47 +/- 8% and 80 +/- 14 hr, respectively, while those of peripheral corneal cells were 41 +/- 10% (P less than 0.1) and 131 +/- 25 hr (P less than 0.001). The mitotic activity of limbal cells was significantly higher than that of peripheral (2.9 +/- 1.2 vs. 0.8 +/- 0.6) (P less than 0.01). These results indicate that human ocular limbal epithelium grows better in culture than does peripheral human corneal epithelium.