Epithelial line from normal human colon mucosa.

An epithelial line was established from an explant culture derived from human colon mucosa exhibiting a normal phenotype by taking advantage of two differences in in vitro cell behavior of mixed cell (epithelial-fibroblast) monolayer [rate of adherence to a plastic surface from a suspension and toxicity to collagenase (25 U/ml medium) in the culture medium]. Cells with an epithelial morphology could be identified at all times throughout the first 5 culture months--first as epithelial sheets migrating from explants, then as small clusters within the fibroblast monolayer, and finally after 5 months of selective culturing as the only cell type present. The line maintained an epithelium-like morphology and growth pattern through 27 continuous culture months (35 subcultures) and was clearly distinguishable from colon fibroblast cultures grown under the same conditions. The ultrastructural features of this line that grew as a continuum included extensive membrane interdigitations with intercellular junctions, tonofilaments, mucus droplets, no Weibel-Palade bodies (characteristic of endothelial cells), and microridges uniformly covering the cell surfaces; all of these features were absent in colon fibroblast cultures. Growth kinetics (generation time, saturation density, and life-span) were distinctly different from those of colon fibroblast cultures grown under the same conditions. During 27 continuous culture months, the cells remained diploid (2-3% hyperdiploidy) and showed no evidence of senescence.