Generation of Lung and Thyroid Tissues from Embryonic Stem Cells using Blastocyst Complementation.

Regeneration or replacement of lung cells or tissues from iPSC- or ESC-derived cells represent future therapies for life-threatening pulmonary disorders but are limited by technical challenges to produce highly differentiated cells able to maintain lung function. Functional lung tissue containing airways, alveoli, vasculature and stroma has never been produced via directed differentiation of ESCs or iPSCs. We sought to produce all tissue components of the lung from bronchi to alveoli by embryo complementation.
To determine whether ESCs are capable of generating lung tissue in Nkx2-1-/- mouse embryos with lung agenesis.
Blastocyst complementation was used to produce chimeras from normal mouse ESCs and Nkx2-1-/- embryos, which lack pulmonary tissues. Nkx2-1-/- chimeras were examined using immunostaining, transmission electronic microscopy, FACS analysis and single cell RNA sequencing.
Although peripheral pulmonary and thyroid tissues are entirely lacking in Nkx2-1 gene deleted embryos, pulmonary and thyroid structures in Nkx2-1-/- chimeras were restored after ESC complementation. Respiratory epithelial cell lineages in restored lungs of Nkx2-1-/- chimeras were derived almost entirely from ESCs, whereas endothelial, immune and stromal cells were mosaic. ESC-derived cells from multiple respiratory cell lineages were highly differentiated and indistinguishable from endogenous cells based on morphology, ultrastructure, gene expression signatures and cell surface proteins used to identify cell types by FACS.
Lung and thyroid tissues were generated in vivo from ESCs by blastocyst complementation. Nkx2-1-/- chimeras can be used as “bioreactors” for in vivo differentiation and functional studies of ESC-derived progenitor cells.