Generation of Alveolar Epithelium Using Reconstituted Basement Membrane and hiPSC-Derived Organoids.

In vitro modeling of alveolar epithelium needs to recapitulate features of both cellular and noncellular components of the lung tissues. Herein, a method is presented to generate alveolar epithelium by using human induced pluripotent stem cells (hiPSCs) and reconstituted or artificial basement membrane (ABM). The ABM is obtained by self-assembling type IV collagen and laminin with a monolayer of crosslinked gelatin nanofibers as backbone and a patterned honeycomb microframe for handling. Alveolar organoids are obtained from hiPSCs and then dissociated into single cells. After replating the alveolar cells on the ABM and a short-period incubation under submerged and air-liquid interface culture conditions, an alveolar epithelium is achieved, showing high-level expressions of both alveolar cell-specific proteins and characteristic tight junctions. Besides, endothelial cells derived from the same hiPSCs are cocultured on the backside of the epithelium, forming an air-blood barrier. The method is generic and can potentially be applied to other types of artificial epithelium and endothelium.