Disease-derived liver organoids as a preclinical screening platform identify Sargassum japonica as an anti-fibrotic candidate.

Liver fibrosis remains an unmet medical need with limited therapeutic options and high translational failure. Conventional two-dimensional stellate cell cultures and cytokine-induced organoids poorly recapitulate in vivo pathology. Here, we establish a physiologically relevant liver fibrosis model by generating organoids directly from carbon tetrachloride (CCl₄)-injured fibrotic mouse liver tissue. These disease-derived organoids preserved key pathological hallmarks, including extracellular matrix remodeling and metabolic dysfunction, showing strong transcriptomic resemblance to fibrotic liver tissue. Using a two-tier screening pipeline, candidate natural products were first evaluated in hepatic stellate cells (in vitro) and subsequently validated in organoids (ex vivo) and murine fibrosis models (in vivo). Sargassum japonica (S. japonica) consistently demonstrated anti-fibrotic efficacy across all models, suppressing collagen deposition and α-SMA expression while restoring hepatic metabolic metabolism. RNA-sequencing revealed concordant downregulation of fibrosis-associated pathways and reactivation of detoxification and lipid metabolism genes, indicating dual mechanisms of action: inhibition of fibrogenesis and promotion of metabolic recovery. These findings highlight S. japonica as a promising anti-fibrotic candidate, and fibrotic liver-derived organoids as a predictive platform for drug discovery and validation. This integrated pipeline provides a translational bridge between in vitro assays and in vivo disease models, accelerating the identification of novel therapeutics for chronic liver disease.