Cultures of bovine tracheal epithelium with differentiated ultrastructure and ion transport

Tracheal epithelial cells were grown on Nuclepore filters coated with human placental collagen. When grown immersed in medium containing fetal bovine serum, cells displayed an undifferentiated ultrastructure (no cilia and a cell height of approximately 10 microns). Short-circuit current (Isc) was approximately 1/10 that of the native epithelium. By contrast, when grown in hormonally defined, serum-free medium with an air interface, cells showed Isc equal to or greater than the original tissue, possessed cilia, and had a cell height of approximately 50 microns. Responses in Isc to mediators were similar to those of the original tissue, but differed from those of dog or human tracheal epithelium. Given the ready availability and low cost of the native tissues, bovine tracheal cultures grown in serum-free medium with an air interface should prove useful in studies of airway epithelial physiology.