Long-Term Culture of Distal Airway Epithelial Cells Allows Differentiation Towards Alveolar Epithelial Cells Suited for Influenza Virus Studies

Imai-Matsushima, Aki; Martin-Sancho, Laura; Karlas, Alexander; Imai, Seiichiro; Zoranovic, Tamara; Hocke, Andreas C.; Mollenkopf, Hans-Joachim; Berger, Hilmar; Meyer, Thomas F.

Organoid models allow long-term culture of cells derived from rapidly regenerating organs using dedicated adult stem cells [12] [13] [14] . However, the regeneration of adult lung epithelium is only activated upon injury, impeding the identification of the cell types involved. Most of the evidence appoints differentiated alveolar epithelial cells as the progenitor cells of the alveolar epithelium, although other reports suggest that specialized stem cells are recruited upon severe alveolar damage [15] . The potential to differentiate alveolar linages from human distal airway stem cells (DASCs) was addressed previously [16] . Human DASCs were found to express P63 and cytokeratin 5 (CK5), which are markers for progenitor cells of the stratified epithelium, and were able give rise to podoplanin + AEI cells and CC10 + airway club cells, but not surfactant protein C + AEII cells [16] . Bove and colleagues grew human AEII cells in culture with feeder cells and the rho kinase inhibitor Y-27632 for N30 population doublings [17] . However, markers of AEII cells were downregulated after the first passage and the phenotype of the cells after feeder removal was not extensively characterized.