Abstract
The periodic cartilage and smooth muscle structures in mammalian trachea are derived from tracheal mesoderm, and tracheal malformation results in serious respiration defects in neonates. To establish a human tracheal mesodermal development model, an in vitro differentiation protocol from pluripotent stem cells was desired. Here we show that endodermal-to-mesodermal canonical Wnt signaling induces trachea progenitors in mouse splanchnic mesoderm. Loss of β-catenin in fetal mouse mesoderm caused loss of Tbx4+ tracheal mesoderm and trachea cartilage agenesis. We found that endodermal Wnt ligands promote mesodermal Tbx4 expression independent of known Nkx2.1-mediated respiratory endoderm development. In vitro, activating Wnt and Bmp signaling in mouse ES cell (ESC)-derived lateral plate mesoderm (LPM) generated tracheal mesoderm containing chondrocytes and smooth muscle cells. For human ESC-derived LPM, SHH activation was required along with Wnt to generate authentic tracheal mesoderm. These findings are foundations for deriving human tracheal mesoderm for applications in tracheal tissue repair.