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 micrograms/ml), epidermal growth factor (10 ng/ml), hydrocortisone (0.5 micrograms/ml), and bovine pituitary extract (25 micrograms/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 beta-D-galactose-(1----3)N-acetyl D-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.