Generation of an alveolar epithelial type II cell line from induced pluripotent stem cells

Differentiation of primary alveolar type II epithelial cells (AEC type II) to AEC type I in culture is a major barrier in the study of the alveolar epithelium in vitro. The establishment of an AEC type II cell line derived from induced pluripotent stem cells (iPSC) represents a novel opportunity to study alveolar epithelial cell biology, for instance in the context of lung injury, fibrosis and repair. In the present study, we generated long lasting AECII from iPSC (iPSC-AEC). Long lasting iPSC-AECII (LL)-iPSC-AECII) displayed morphological characteristics of AECII including growth in a cobble stone monolayer, the presence of lamellar bodies and microvilli as shown by electron microscopy. Also, (LL)-iPSC-AECII expressed AEC type II proteins such as cytokeratin, surfactant protein C and lysotracker DND 26 (a marker for lamellar bodies). Furthermore, the (LL)-iPSC-AECII exhibited functional properties of AECII by an increase of transepithelial electrical resistance (TERR) over time, secretion of inflammatory mediators in biologically relevant quantities (interleukin-6, interleukin-8) and efficient in vitro alveolar epithelial wound repair. Consistent with the AECII phenotype, the cell line showed the ability to uptake and release surfactant protein B, to secrete phospholipids and to differentiate into AEC type I. In summary, we established a long lasting, but finite AEC type II cell line derived from iPSC as a novel cellular model to study alveolar epithelial cell biology in lung health and disease.