Human pluripotent stem cells (not shown) can be differentiated to become three-dimensional bunches of cells that are fated to anterior foregut endoderm cells. When Dye et al. plated such foregut spheroids (green circles) into a substrate (Matrigel) and cultured them in vitro for approximately 8 weeks (A), they observed levels of differentiation similar to embryonic human lungs, including ciliated cells (light green), basal cells (blue) and rare secretory cells (not shown). However, when Dye et al. seeded foregut spheroids onto synthetic scaffolds and cultured them for approximately 1 week in vitro, and then transplanted them into the epididymal fat pad of immunocompromised mice for 8–15 weeks (B), they observed greater levels of differentiation, including ciliated cells (light green), basal cells (blue), goblet cells (red) and secretory cells (magenta) lining the surfaces of tubular airway-like structures. The organoids also appeared to be connected to the vasculature of the mice.