Development of novel in vitro human alveolar epithelial cell models to study distal lung biology and disease [scRNA-seq]

To address the need for human alveolar epithelial cell (AEC)-derived lines to more suitably model distal lung diseases, we have generated and characterized novel immortalized cell lines derived from human AECs. We used a combination of the ROCK inhibitor, Y-27632, and lentiviral transduction of SV40 Large T antigen of previously cryopreserved isolated human alveolar epithelial type 2 (AT2) cells to generate immortalized AECs. These AEC lines proliferate well on standard tissue culture dishes forming an epithelial monolayer and express lung progenitor markers SOX9 and SOX2. When grown in 3D culture with lung fibroblasts, the cells form NKX2-1+ organoids expressing more mature alveolar lung markers, AQP5 and GPRC5A. Single cell RNA-sequencing of one AEC line comparing cells in 2D versus 3D revealed increased cellular heterogeneity and an induction of cytokine and lipoprotein signaling in 3D culture, reflecting interactions with the microenvironment during organoid formation. Taken together, these data show our novel progenitor-like AEC lines retain a genetic and structural memory of their alveolar cell lineage despite long-term expansion, providing a valuable new system to model the distal lung in vitro. We compared cells of the SV40 Large T antigen-immortalized AEC line, AEC-ON, grown in 2D monolayer versus 3D organoids by single cell RNA-sequencing.