Characterization of epithelial cell cultures derived from human tracheal glands

Cultures of normal human tracheal gland epithelial cells that exhibit functional differentiation have been propagated in serum-free medium supplemented with insulin (5 μg/ml), epidermal growth factor (10 ng/ml), hydrocortisone (0.5 μg/ml), and bovine pituitary extract (25 μg/ml). The cells retain many characteristics of epithelial cells including microvilli on cell surfaces, desmosomes between cells, and tonofilaments in the cytoplasm. In addition, they exhibit keratin-positive titers and react positively with Peanut agglutinin, which is specific for the disaccharide β-d-galactose-(l→ 3)N-acetyld-galactosamine, a major component of mucin glycoprotein. The cells also exhibit normal Cl⁻ channel activity which was enhanced by the cAMP agonist Forskolin. The major component of the cellular secretion was hyaluronic acid; approximately 10% of the void volume material was resistant to hyaluronidase and may contain material similar to mucin glycoprotein. Some of the cell cultures have been maintained in serum-free conditions for 6 to 7 passages. This model will be important to study regulation of ion-channel activities and mucous glycoprotein secretion and to compare such regulations with the tracheal mucosal epithelial cells already established. This research was supported by USPHS grants HL 41979 and HL 33142 from the National Heart, Lung and Blood Institutes.