[3H]thymidine-labeled colonic epithelial cells and mucosa in mice and man.

Since normal epithelial cell proliferation occurs chiefly in the lower two thirds of colonic crypts, the presence of aberrant DNA-synthesizing cells (tritiated thymidine labeled) at the mouth and on the surface of colonic crypts is being assessed as a predictive indicator of the development of neoplasia in patients at high risk. These would include patients with previous polyps or colon cancer or family history of either or both. Surface cells are obtained by pulsatile saline lavage of the lower bowel and incubated with tritiated thymidine ([3H]TdR) for autoradiographic observation. Findings in each high-risk category are presented and compared with [3H]TdR labeling data from a biopsy taken at the close of the procedure. The lavage technique has also been carried out on mice injected with the colon carcinogen 1,2-dimethylhydrazine (DMH). Mice were demonstrated to have [3H]TdR-labeled cells and cellular atypic while being hemoccult negative and asymptomatic for overt disease. Evaluation of human material preliminarily demonstrated the presence of surface-labeled epithelial cells in a high percentage of patients at risk for colon cancer.