Growth regulation of serum-free cultures of epithelial cells from normal human buccal mucosa.

Human buccal epithelial cells have been reared from explants maintained in supplemented MCDB 153 medium. Primary epithelial outgrowths show typical structural features and uniformly express keratins; subunit analyses demonstrate expression of keratins 5, 6, 14, 16/17, and 19. The cells exhibit up to 6% colony forming efficiency and divide at about 0.8 population doublings per day on fibronectin/collagen-coated dishes at clonal density. Studies of markers of proliferation and differentiation in buccal epithelial cells indicate that epidermal growth factor, cholera toxin, retinoic acid, and pituitary extract each exhibit a distinctive ability to enhance growth and variably affect cell migration and cell surface area. Transforming growth factor beta-1 inhibits growth and increases surface area without affecting migration, involucrin expression, and cross-linked envelope formation. Moreover, exposure of cells to fetal bovine serum, the tumor promoting agent 12-O-tetradecanoylphorbol-13-acetate or an elevated Ca2+ concentration (from 0.1 to 1 mM) inhibits growth and induces squamous differentiation as indicated by inhibition of migration, increases in surface area, involucrin expression, or formation of cross-linked envelopes. The results show that epithelial cells can be reproducibly derived from explant cultures of human buccal mucosa specimens and the cells transferred under serum-free conditions. Buccal epithelial cells in culture undergo a pattern of growth and differentiation that mimics parakeratinization in vivo and variably respond to several agents shown to modulate growth of cells that originate from other types of epithelia.