Density and substrata are important in lung type II cell transdifferentiation in vitro

Morphological techniques and metabolic cell marker assays were used to stud y the transdifferentiation of pulmonary type II epithelial cells to type I- like cells in vitro. In the lung this process is important during remodelli ng and alveolar repair. Type II cell phenotype was best maintained over eig ht days when densely packed cells were plated out on a commercially availab le extracellular matrix. Such cells retained type II cell characteristics ( lamellar bodies, high activities of gamma glutamyl transpeptidase and alkal ine phosphatase) but expressed low levels of rTl(40) a surface protein mark er of type I cells. In contrast, low density cultures, irrespective of subs tratum, exhibited rapid cell spreading, loss of lamellar bodies, loss of ty pe II cell enzyme markers and expressed high levels of rTl(40). Conditions have been described whereby the same isolate of type II cells can be used t o produce differential epithelial phenotypes and use can be made of this fo r further characterisation or to investigate the effect of toxins on differ ent lung cell types in vitro. (C) 1999 Elsevier Science Ltd. All rights res erved.