Ion transport in epithelial spheroids derived from human airway cells

Pedersen, Peter Steen, Ole Frederiksen, Niels-Henrik Holstein-Rathlou, Per Leganger Larsen, and Klaus Qvortrup. Ion transport in epithelial spheroids derived from human airway cells. Am. J. Physiol. 276 (Lung Cell. Mol. Physiol. 20): L75–L80, 1999.—In the present study, we describe a novel three-dimensional airway epithelial explant preparation and demonstrate its use for ion transport studies by electrophysiological technique. Suspension cultures of sheets of epithelial cells released by protease treatment from cystic fibrosis (CF) and non-CF nasal polyps developed freefloating, monolayered epithelial spheres, with the apical, ciliated cell membrane facing the bath and the basolateral cell membrane pointing toward a fluid-filled lumen. Microelectrode impalement of both non-CF and CF spheroids revealed lumen-positive transepithelial electrical potential differences (PDs) that were inhibited by amiloride, indicating that the spheroids were inflated due to amiloride-sensitive Na1 absorption followed by water. Transformation to a Cl2 secretory state was achieved by addition of ATP to the bath, leading to the development of a diphenylamine-2-carboxylate-sensitive PD. A cAMP-induced increase in PD was seen in non-CF spheroids only. In response to hydrocortisone treatment, Na1 transport 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 the airway surface epithelium and is suitable for studies of transport mechanisms and regulation.