Hepatic Stellate Cell Heterogeneity in Chronic Liver Fibrosis: Functional States and Translational Opportunities

Hepatic stellate cell (HSC) activation has traditionally been described as a binary transition from vitamin A-rich quiescent cells to alpha-smooth muscle actin-positive, collagen-producing myofibroblast-like cells. Advances in single-cell RNA sequencing, single-nucleus RNA sequencing, spatial transcriptomics, and chromatin-accessibility profiling now reveal a more complex and dynamic landscape. During chronic liver injury, HSCs can adopt five overlapping activation-associated states characterized by injury sensing, inflammatory signaling, proliferation, extracellular matrix production and contractility, together with a senescent state that represents a possible fate of activated HSCs. These states differ in their molecular markers, spatial distribution, regulatory pathways, and interactions with hepatocytes, liver sinusoidal endothelial cells, macrophages, natural killer cells, and cholangiocytes. Importantly, they are not fixed lineages and may coexist or interconvert during fibrosis progression and regression. This review revisits the classical quiescent-activated framework and proposes a state-based approach for interpreting HSC heterogeneity. We summarize the defining features and translational relevance of six major HSC functional states, discuss their multicellular niches, and highlight the opportunities and limitations of function-selective therapeutic targeting. A reproducible classification that integrates molecular identity, spatial context, and causal function may help refine antifibrotic treatment strategies.