Engineering distal pulmonary epithelium from induced pluripotent stem cell (iPSC)-derived alveolar cells

Background: Lung transplantation remains the only treatment for many end-stage lung diseases. However, donor organ shortage and the need for immunosuppression limit clinical impact. Cadaveric lungs can be decellularized to yield scaffolds that provide a suitable platform for tissue regeneration. Directed differentiation of human iPSCs toward a lung epithelial fate is a promising approach to facilitate the goal of whole organ regeneration with patient-specific cells. Objective: To investigate the capacity of iPSC-derived alveolar cells to form distal pulmonary epithelium on acellular lung scaffolds. Methods: Human iPSCs carrying Nkx2.1-GFP and SPC-TdTomato reporters were differentiated towards a lung alveolar fate by established protocols. SP-C+ alveolar cells were delivered to decellularized rat lungs (n=6) to repopulate the distal niche. Epithelial tissue formation was induced through extended ex vivo biomimetic culture. Regenerated lungs were analyzed for tissue architecture and cell fate. Acellular human lung slices were also repopulated with iPSC-derived cells in vitro. Seeded lung slices (n=12) were cultured, then tissue structure and cell fate were also analyzed. Results: Formation of early distal lung epithelial tissue with mature type II alveolar cell phenotype, expressing Nkx2.1, E-Cadherin, SP-C, SP-B was observed. We also identified AQP5 positive cells, which may identify a type 1 alveolar fate. Similar findings were seen on human lung slices. Conclusions: Human iPSC-derived alveolar epithelial cells can form distal lung epithelium on both rodent and human lung scaffolds, demonstrating the future potential for patient-specific lung regeneration at a transplantable scale.