In Vivo Generation of Lung and Thyroid Tissues from Embryonic Stem Cells Using Blastocyst Complementation

The regeneration and replacement of lung cells or tissues from induced pluripotent stem cell- or embryonic stem cell-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 have never been produced via directed differentiation of embryonic stem cells (ESCs) or induced pluripotent stem cells. 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 mouse embryos with lung agenesis. Blastocyst complementation was used to produce chimeras from normal mouse ESCs and embryos, which lack pulmonary tissues. chimeras were examined using immunostaining, transmission electronic microscopy, fluorescence-activated cell sorter analysis, and single-cell RNA sequencing. Although peripheral pulmonary and thyroid tissues are entirely lacking in gene-deleted embryos, pulmonary and thyroid structures in chimeras were restored after ESC complementation. Respiratory epithelial cell lineages in restored lungs of 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 fluorescence-activated cell sorter. Lung and thyroid tissues were generated from ESCs by blastocyst complementation. chimeras can be used as "bioreactors" for differentiation and functional studies of ESC-derived progenitor cells.