Lung regeneration is dependent on the availability of progenitor lung cells. Large numbers of self-renewing, patient-specific induced pluripotent stem cell-derived alveolar epithelial cells (iPSC-AECs) are needed to adequately recellularize whole-organ constructs. Prior methods to generate functional iPSC-AECs are not feasible for large-scale cell production. We present a novel protocol to produce iPSC-AECs, which is scalable for whole-organ regeneration. Differentiation of iPSCs was performed with genetically modified iPSCs with fluorescent reporters, which underwent differentiation in a stepwise protocol mimicking lung development. Cells were purified, sorted, and embedded in a liquid Matrigel precursor either to form adherent droplets or to form cell-laden Matrigel spheroids, which were subsequently transferred to spinner flasks with media as floating droplets. After culture, monolayer spheres of iPSC-AECs were isolated to form single cell suspensions. Equal numbers of iPSC-AECs from the two culture conditions were seeded into decellularized lung scaffolds. IPSC-AECs cultured in floating droplets were significantly more proliferative than those in adherent droplets, with significantly higher total cell counts and Ki67 expression. Equivalent expression of the distal lung markers was observed for both culture conditions. Lungs recellularized from both culture groups had similar histological appearance. Media changes took significantly less time with the floating droplet method and was more cost effective. The floating droplet culture method demonstrated enhanced proliferative capacity, stable distal lung epithelial phenotype, and reduced resources compared with prior culture methods. In this study, we provide a means for iPSC-AEC production for regeneration of whole-lung constructs. Impact statement We describe a novel culture method for induced pluripotent stem cell-derived alveolar epithelial cell (AEC) expansion with enhanced proliferative capacity and reduced resource requirements compared with previously described methods. This method is scalable for human whole-lung regeneration bioengineering or could be automated for commercial cell production. This culture method may have implications for the differentiation of type I AECs from type II AECs.
Keywords: alveolar epithelial cells; bioengineering; cell proliferation; hydrogels; induced pluripotent stem cells; lung; lung transplantation; regeneration.