Extracellular matrix stiffness governs mesenchymal stromal cell therapy for liver fibrosis via the ANTXR1-Hippo-YAP axis

Liver fibrosis (LF) is a dynamic process characterized by the accumulation of extracellular matrix (ECM). In this study, the therapeutic potential of mesenchymal stromal cells (MSCs) in different ECM stiffness was investigated, and the underlying mechanisms were explored. In vivo, we established an advanced LF rats model with increased ECM stiffness using carbon tetrachloride (CCl₄), while a concanavalin A (ConA)-induced acute injury rats model served as a low-stiffness control. Histological and serum analyses were utilized to evaluate the therapeutic effects of MSCs. In vitro, a tunable 3D hydrogel system was employed to model different ECM stiffnesses, and molecular biology approaches were applied to assess the resultant changes in the immunomodulatory function of MSCs. In contrast to their reparative function in soft matrices, high matrix stiffness reprograms MSCs toward a phenotype that promotes inflammation and fibrosis. Mechanistically, the mechanoreceptor ANTXR1 in MSCs senses the stiffened microenvironment and inactivates the Hippo pathway, leading to YAP dephosphorylation and nuclear translocation. Nuclear YAP then drives the extensive expression of inflammatory cytokines (TNF-α, IFN-γ, IL-6), which amplifies the fibrotic progression. We identify the mechanoreceptor ANTXR1 as a key sensor of increased ECM stiffness in MSCs, which inactivates the Hippo pathway to promote YAP-driven transcription and subsequent inflammatory cytokine expression. Our findings reveal that ECM stiffness critically influences the immunomodulatory function of MSCs, suggesting its key role in guiding the development of future MSC-based therapies.