Effects of vitamin A on growth and differentiation of human tracheobronchial epithelial cell cultures in serum-free medium.

Differentiating epithelial cell cultures from human tracheobronchial epithelium have been propagated in serum-free medium. The major objective of this study was to examine the trophic effects of vitamin A on cell multiplication and morphology of the tracheal cell cultures. The cellular responses were analyzed in terms of growth kinetics, morphological and ultrastructural alterations and secretion of glycoconjugates. Cell cultures in control medium exhibited characteristics of epithelial cells including microvilli on cell surfaces, desmosomes between cells, and numerous secretory vesicles in the cytoplasm. Vitamin A at 10(-6) M and 10(-7) M inhibited cell replication and enhanced the secretion of [3H]glucosamine-labeled glycoconjugates. Further, vitamin A increased the production of plasma membrane vesicles and acquisition by the cells of a highly secretory ultrastructure. This in vitro model of human epithelial cells will be important in the investigation of various aspects of growth and differentiation.