Despite a significant improvement in the availability of therapeutic options to treat lung diseases, pulmonary disease still remains a major cause of morbidity and mortality around the world. Currently there are limited opportunities to study human lung disease either in vivo and in vitro. Using induced pluripotent stem cells (iPSC) we have generated a reproducible differentiation protocol to make mature post‐mitotic multiciliated cells in a functional airway epithelium. iPSC were generated from human skin biopsies and differentiated via FOXA2+SOX17+ definitive endoderm (>90% efficiency) to FOXA2+NKx2.1+ anterior foregut endoderm, FOXA2+NKx2.1+SOX2+ (~50% efficiency) pulmonary endoderm and then matured in an air liquid interface. Robust multiciliogenesis occurred when Notch signaling was inhibited and was confirmed by; i) the assembly of multiple pericentrin stained centrioles at the apical surface, ii) expression of transcription factor FOXJ1 and iii) presence of multiple acetylated tubulin labeled cilia projections in individual cells. The presence of NKx2.1+CC10+ Clara cells, MUC5A/C+ goblet cells and FOXA2+p63+ basal cells was also confirmed showing we are generating a complete polarized epithelial cell layer comprised of all relevant cell types. Functional cAMP activated and CFTRinh‐172 sensitive CFTR currents were recorded in isolated epithelial cells by whole cell patch clamp technique. Furthermore, we have corrected the deltaF508 mutation in the CFTR gene (>80% of all cases of CF) using a combination of CRISPR‐Cas9 endonuclease‐mediated genome editing and piggyBac transposase technologies, in the CF patient‐derived iPSC. The generation of mature multiciliated cells in a human iPSC differentiated respiratory epithelium and the ability to correct disease causing mutations provides a significant advancement toward modeling a number of human respiratory diseases in vitro. Grant Funding Source: Supported in part by CIRM and the Berger Foundation

SUMMARY Lung disease is a major cause of death in the USA, with current therapeutic approaches only serving to manage symptoms. The most common chronic and life-threatening genetic disease of the lung is Cystic fibrosis (CF) caused by mutations in the cystic fibrosis transmembrane regulator (CFTR). We have generated induced pluripotent stem cells (iPSC) from CF patients carrying a homozygous deletion of F508 in the CFTR gene, which results in defective processing of CFTR to the cell membrane. This mutation was precisely corrected using CRISPR to target corrective sequences to the endogenous CFTR genomic locus, in combination with a completely excisable selection system which significantly improved the efficiency of this correction. The corrected iPSC were subsequently differentiated to mature airway epithelial cells where recovery of normal CFTR expression and function was demonstrated. This isogenic iPSC-based model system for CF could be adapted for the development of new therapeutic approaches.

There is evidence that donor-derived dendritic cells (DC), particularly those at a precursor/immature stage, may play a role in the immune privilege of liver allografts. Underlying mechanisms are poorly understood. We have examined the influence of in vitro generated mouse liver-derived DC progenitors (DCp) on proliferative, cytotoxic, and Th1/Th2 cytokine responses induced in allogeneic T cells. Liver DCp, propagated in GM-CSF from C57B10 mice (H2b), induced only minimal proliferation, and weak cytotoxic responses in allogeneic (C3H; H2k) T cells compared with mature bone marrow (BM)-derived DC. Flow-cytometric analysis of intracellular cytokine staining revealed that mature BM DC, but not liver DCp, elicited CD4+ T cell production of IFN-γ. Intracellular expression of IL-10 was very low in both BM DC- and liver DCp-stimulated CD4+ T cells. Only stimulation by liver DCp was associated with IL-10 secretion in primary MLR. Notably, these liver DCp cocultured with allogeneic T cells stained strongly for IL-10. Following local (s.c.) injection in allogeneic recipients, both BM DC and liver DCp homed to T cell areas of draining lymph nodes and spleen, where they were readily detected by immunohistochemistry up to 2 wk postinjection. Liver DCp induced clusters of IL-10- and IL-4-secreting mononuclear cells, whereas Th2 cytokine-secreting cells were not detected in mice injected with mature BM DC. By contrast, comparatively high numbers of IFN-γ+ cells were induced by BM DC. Modulation of Th2 cytokine production by donor-derived DCp may contribute to the comparative immune privilege of hepatic allografts.

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