Assessment of chemically induced DNA repair in primary cultures of human bronchial epithelial cells

A procedure has been developed to assess chemically induced DNA repair in freshly isolated, primary cultures of human bronchial epithelial (HBE) cells. HBE cells were isolated from eight samples of autopsy material or surgical specimens and incubated with test chemicals and [3H]thymidine. Viability as measured by trypan blue exclusion averaged 90%. Chemically induced DNA repair was assessed as unscheduled DNA synthesis (UDS) by quantitative autoradiography. The direct-acting agent methyl methanesulfonate induced DNA repair in HBE cells in all eight cases studied, indicating that the cultures were viable and capable of DNA repair in response to DNA damage. Benzo(a)pyrene induced DNA repair in all cultures whereas dimethylnitrosamine failed to induce UDS in any culture, suggesting an organ-specific pattern of metabolic activation. 1,6-Dinitropyrene was positive in cultures prepared from autopsy material but negative in cultures prepared from surgical specimens. Formaldehyde did not induce UDS in any sample examined. This system may be useful in assessing the genotoxic potential of environmental chemicals in human bronchial epithelial cells, give an indication of interindividual variability, and provide valuable information for comparison to proposed animal models for the human bronchus.