2D cell culture on soft hydrogel drives an endoplasmic reticulum stress-dependent S quiescence underlying molecular traits of pulmonary basal cells

By preserving progenitor characteristics, cell culture on soft hydrogel represents a practical tool in regenerative medicine compared with conventional rigid plastic. However, the mechanism by which the mechanical microenvironment determines progenitor phenotype, and its relevance to human biology, remain poorly described. Thanks to an innovation enabling the generation of uniform multi-well hydrogels, we show that 2D culture on mechanomimetic supports leads to an atypical S-phase quiescence and prevents cell drift, while preserving the differentiation capacities of human bronchoepithelial cells. Mechanistically, defects in proteostasis and basal endoplasmic reticulum stress (ERS) underlie the quiescent phenotype and resistance to ERS-induced apoptosis by metabolic stress. Furthermore, analysis of available single cell data of the human lung confirmed that these molecular features are consistent with those of pulmonary basal cells. Overall, this study demonstrates that mechanomimetic supports are relevant devices for characterizing novel molecular events that govern progenitor biology in human tissues. ### Competing Interest Statement A. N, C. M. are shareholders of the Cell&Soft company.