CRISPR-engineered human lung organoids with a biomolecular condensate reporter enable mechanistic toxicity monitoring.

Understanding how chemical stress perturbs human lung physiology requires models that capture dynamic molecular responses in real time. Here, we established a CRISPR/Cas9-engineered human induced pluripotent stem cell (hiPSC)-derived lung organoid expressing endogenous G3BP1-mCherry, enabling live, non-destructive visualization of stress granule (SG) formation under toxicant exposure. The organoids recapitulated airway and alveolar epithelial diversity and displayed lamellar body-like ultrastructures, indicating advanced maturation. Time-lapse imaging revealed rapid and reversible SG dynamics across chemically distinct stressors, while cytotoxicity assays showed that these organoids are significantly more sensitive than conventional 2D or cancer-derived lung models. Importantly, SG dynamics were linked to exposure duration-dependent changes in epithelial barrier integrity, indicating that SG formation precedes overt epithelial injury and serves as an early indicator of toxicant-induced cellular stress. Integration with high-content screening enabled quantitative, image-based analysis of cellular stress phenotypes, greatly enhancing throughput and mechanistic insight, thereby provided next-generation New Approach Methodologies for lung toxicity assessment. Together, this hiPSC-derived lung organoid SG reporter platform links early molecular stress adaptation to tissue-level responses, offering a predictive and mechanistically informative framework for human-relevant lung toxicity evaluation.