Human umbilical cord-derived mesenchymal stromal cells alleviate liver cirrhosis through the Hippo/YAP/Id1 pathway and macrophage-dependent mechanism

Few effective anti-fibrotic therapies are currently available for liver cirrhosis. Mesenchymal stromal cells (MSCs) ameliorate liver fibrosis and contribute to liver regeneration after cirrhosis, attracting much attention as a potential therapeutic strategy for the disease. However, the underlying molecular mechanism of their therapeutic effect is still unclear. Here, we investigated the effect of human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) in treating liver cirrhosis and their underlying mechanisms. We used carbon tetrachloride (CCl4)-induced mice as liver cirrhosis models and treated them with hUC-MSCs via tail vein injection. We assessed the changes in liver function, inflammation, and fibrosis by histopathology and serum biochemistry and explored the mechanism of hUC-MSCs by RNA sequencing (RNA-seq) using liver tissues. In addition, we investigated the effects of hUC-MSCs on hepatic stellate cells (HSC) and macrophages by in vitro co-culture experiments. We found that hUC-MSCs considerably improved liver function and attenuated liver inflammation and fibrosis in CCl4-injured mice. We also showed that these cells exerted therapeutic effects by regulating the Hippo/YAP/Id1 axis in vivo. Our in vitro experiments demonstrated that hUC-MSCs inhibit HSC activation by regulating the Hippo/YAP signaling pathway and targeting Id1. Moreover, hUC-MSCs also alleviated liver inflammation by promoting the transformation of macrophages to an anti-inflammatory phenotype. Our study reveals that hUC-MSCs relieve liver cirrhosis in mice through the Hippo/YAP/Id1 pathway and macrophage-dependent mechanisms, providing a theoretical basis for the future use of these cells as a potential therapeutic strategy for patients with liver cirrhosis.