Dye, B.R. et al. eLife 4, e05098 (2015).

Stem cells can be directed to take different fates and, in some cases, to form complex three-dimensional (3D) structures with features of intact organs in vitro. Previous work showed that when FGF and WNT signaling is stimulated, endoderm derived from human pluripotent stem cells will self-organize into 3D spheroids containing mesenchymal and polarized epithelial cells. Dye et al. demonstrate that inhibiting BMP while stimulating HH signaling during this process generates lung organoids that can subsequently be expanded robustly in FGF10 medium. The organoids include cell types of the proximal lung epithelium surrounded by mesenchymal tissue and generate airway-like structures. RNA sequencing analysis showed that the organoids strongly resemble human fetal lung and may therefore serve as a tool for the study of lung development and disease.