MORPHOLOGICAL AND HISTOLOGICAL STUDIES ON 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 i n vitro carcinogenesis, an experimental system for organ cultures was developed in which human respiratory epithelia from tracheal biopsies differentiate within six weeks. The mucosal and submucosal layer of sm all tracheal biopsies was cut into pieces measuring 3 x 3 and 5 x 5 mm (2), respectively, and placed on Gelita cubes (Braun-Melsungen, German y) measuring 10 x 10 x 10 mm(3) with the epithelium facing up. The cul ture medium (RPMI 1640 supplemented with 10% fetal calf serum, 200 mM L-glutamine, 100 IU/ml penicillin, and 100 mu g/ml streptomycin) was a dded in a way that the tissue lay between the medium and air. Gelita d eteriorates in about two to three weeks. However, the cultures are eas ily transfered to fresh Gelita cubes using the rest of the old Gelita. These organ cultures were fixed at regular intervals, and histologica l sections were stained with hematoxylin eosin or monoclonal antibodie s against cytoskeletal intermediate filament proteins. These morpholog ical and histological studies revealed that the epithelial cells diffe rentiated under these conditions in at least 39 days. The mesenchymal elements remained viable without showing strong proliferation. The imp lication of these techniques for studying carcinogenesis in vitro is d iscussed.