Comparison of central and peripheral human corneal epithelium in tissue culture

Past attempts to grow human corneal epithelium in culture had limited success, with confluence rarely attained. This work is to determine whether different areas of human corneal epithelium grow better in tissue culture. We compared the extent, the mitotic rates, and morphology of outgrowths and histology of explants from central and peripheral human corneas in culture. Explants, 2 mm in diameter, removed from eye bank eyes, were placed epithelial side up on a culture dish with modified SHEM tissue culture medium (Jumblatt et al, 1983). After 7 days, the tissues were fixed, stained and the area of outgrowths from explants measured using an image processor. For eight eyes from donors averaging 66 yr old, the average area of central outgrowths was 7.8 +/- 1.1 mm2, while that of peripheral outgrowths was 52.8 +/- 5.2 mm2 (P less than 0.001). The mitotic rate of outgrowths of central epithelium was significantly less than that of peripheral epithelium (1.1 +/- 0.5% vs 18.8 +/- 0.8%) (P less than 0.001). After 14 days, central outgrowths had not attained confluence and consisted of large cells. Peripheral outgrowths had attained confluence and consisted of small polygonal cells. Histology of explants showed that only one layer of epithelium remained on the stroma in central explants, but several layers were present on the peripheral explants. Thus, peripheral human corneal epithelium grows better in culture than does central human corneal epithelium.