Exposure of organ cultures from human tracheal epithelium to chemical carcinogens and subsequent long-term co-cultivation with autologous isotopic fibroblasts.

As a continuation of previous experiments introducing an extracorporeal model for transformation of human respiratory epithelium that might be able to mimic a spontaneously occurring malignant tumor, we prepared organ cultures from tracheal specimens and exposed them repeatedly to chemical carcinogens, using benzo(a)pyrene and methylnitronitrosoguanine for 6 weeks. We then tried to select possibly initiated cells by subsequent co-cultivation with autologous isotopic fibroblasts for 2 years. Nontreated controls were maintained from the same specimens and cultured in the same manner. By this technique we selected from specimen La24 three long-living cell lines with varying morphology and an antigenic pattern indicating dedifferentiation. The cells expressed simultaneously a panel of cytokeratins, vimentin and neuroectodermal antigens. Transplantation of these cell lines under the subrenal capsule of athymic mice resulted in tumorlike nodules of limited size. Success rate was dependent on time of previous in vitro culture and carcinogen treatment. None of the lines produced invasive or metastasizing tumors.