Single-cell analysis of heterogeneity in reverted hiPSC-derived human hepatic stellate cells.

Background & Aims: Activated HSCs are known to drive fibrogenesis, but their fate following injury resolution remains unclear. We aimed to investigate whether human activated HSCs revert to a less activated state, and to characterize features of such reversion using a human induced pluripotent stem cell (hiPSC)-derived multicellular liver model. Methods: We used a hiPSC-derived liver culture containing hepatocytes, HSCs, and macrophages. HSCs were activated by HCV infection or a lipotoxic milieu modeling metabolic dysfunction-associated steatotic liver disease (MASLD) and subjected to injury resolution through antiviral treatment or replacement with a healthy medium. Reverted HSCs were characterized via gene expression profiling, functional assays, and single-cell RNA sequencing (scRNA-seq). The role of macrophage-derived IL-10 in HSC reversion was investigated through receptor knockdown and cytokine treatment experiments. Results: Following either HCV clearance or withdrawal of lipotoxic stress, activated HSCs reverted to a less activated state, regaining lipid droplets and vitamin A storage while re-expressing quiescent HSC markers. scRNA-seq revealed heterogeneity among reverted HSCs, identifying subpopulations expressing apoptotic, senescent, or quiescent-like signatures. A distinct lipid-high, PTK2-low population closely resembled naïve quiescent HSCs. Functional assays demonstrated that rHSCs retained partial quiescence but exhibited heightened sensitivity to fibrogenic re-stimulation (n = 4, Conclusions: Activated human HSCs demonstrate plasticity, reverting to a quiescent-like state following resolution of viral or metabolic injury, although they remain primed for reactivation. Macrophage-derived IL-10 plays a critical role in driving this reversion by regulating vitamin A metabolism. These findings provide insights into HSC dynamics and suggest potential therapeutic avenues for liver fibrosis by targeting HSC reversion. Impact and implications: Removing the cause of liver injury-curing hepatitis C or withdrawing lipotoxic stress-allows scar-forming liver cells (hepatic stellate cells) to partly revert to a healthier, vitamin-A-storing state; single-cell profiling reveals its heterogeneity and identify a subset nearing true quiescence. This rebound depends on intercellular interaction, in part on the immune signal IL-10 from macrophages, yet reverted cells remain easier to re-activate. These findings provide insights into dynamics of hepatic stellate cells and suggest potential therapeutic avenues for liver fibrosis by targeting stellate cell reversion.