Epithelial and mesenchymal compartment during differentiation of human iPSC into functional bronchial epithelium

Abstract

<b>Background:</b> Induced pluripotent stem cells (iPSC) provide a new approach to model COPD. We have generated a functional air-liquid interface bronchial epithelium from human iPSC (iALI) and focus on the characterization of both mesenchymal and epithelial iALI compartments before and after pollution exposure. <b>Objective/Methods:</b> To modelize COPD and study epithelial-mesenchymal crosstalk, we performed single-cell mRNA sequencing before and after exposure to calibrated PM2.5 pollutants (City of Prague 2005) in EpCAM+ vs EpCAM- sorted cells. RT-QPCR and immunofluorescence were used to assess the exposure process. <b>Results:</b> iALI contains all the bronchial epithelial cell subtypes such as ciliated cells, basal cells, neuroendocrine cells, club cells and goblet cells. Furthermore, an EPCAM-COL1A1+DCN+ stromal compartment is identified below the bronchial epithelial layer of iALI. It contains several cell populations such as 1/myofibroblasts characterized by contractile genes such as CCN1 and TAGLN and 2/ a transition population expressing epithelial to mesenchymal transition transcription factor SNAI2 and ZEB1/2. This stromal cell compartment expressed FGF10 while its receptor FGFR2 was expressed on the adjacent epithelium suggesting an epithelial-mesenchymal crosstalk. Under PM2.5 exposure, MUC5B was induced in the EpCAM+ sorted epithelial cells, while CYP1B1 was induced in the EpCAM- mesenchyme, suggesting an adaptive response to exposome. <b>Conclusion:</b> These data suggest that an epithelial-mesenchymal crosstalk is essential to iALI differentiation and maintenance. Furthermore, we show that iALI is a promising tool to model the adaptive response to exposome.