[Morphologic and immunohistochemical studies of organ cultures of human tracheal biopsies].

Most likely the transformation of epithelial cells to carcinoma cells takes place during the process of differentiation. In order to study in vitro carcinogenesis, an experimental system for organ cultures was developed in which human respiratory epithelial from tracheal biopsies differentiate within six weeks. The mucosal and submucosal layer of small tracheal biopsies was cut into pieces measuring 3 x 3 and 5 x 5 mm2, respectively, and placed on Gelita cubes (Braun-Melsungen, Germany) measuring 10 x 10 x 10 mm3 with the epithelium facing up. The culture medium (RPMI 1640 supplemented with 10% fetal calf serum, 200 mM L-glutamine, 100 IU/ml penicillin, and 100 micrograms/ml streptomycin) was added in a way that the tissue lay between the medium and air. Gelita deteriorates in about two to three weeks. However, the cultures are easily transferred to fresh Gelita cubes using the rest of the old Gelita. These organ cultures were fixed at regular intervals, and histological sections were stained with hematoxylin eosin or monoclonal antibodies against cytoskeletal intermediate filament proteins. These morphological and histological studies revealed that the epithelial cells differentiated under these conditions in at least 39 days. The mesenchymal elements remained viable without showing strong proliferation. The implication of these techniques for studying carcinogenesis in vitro is discussed.