Ion transport in epithelial spheroids derived from human airway cells

In the present study, we describe a novel three-dimensional airway epitheli al explant preparation and demonstrate its use for ion transport studies by electrophysiological technique. Suspension cultures of sheets of epithelia l cells released by protease treatment from cystic fibrosis (CF) and non-CF nasal polyps developed free-floating, monolayered epithelial spheres, with the apical, ciliated cell membrane facing the bath and the basolateral cel l membrane pointing toward a fluid-filled lumen. Microelectrode impalement of both non-CF and CF spheroids revealed lumen-positive transepithelial ele ctrical potential differences (PDs) that were inhibited by amiloride, indic ating that the spheroids were inflated due to amiloride-sensitive Na+ absor ption followed by water. Transformation to a Cl- secretory state was achiev ed by addition of ATP to the bath, leading to the development of a diphenyl amine-2-carboxylate-sensitive PD. A cAMP-induced increase in PD was seen in non-CF spheroids only. In response to hydrocortisone treatment, Na+ transp ort reflected by amiloride-sensitive PD increased and more so in CF than in non-CF spheres. We concluded that this preparation is a useful model for t he airway surface epithelium and is suitable for studies of transport mecha nisms and regulation.