Background: The development of preclinical models integrating human immune components represents a key advance for for the predictive evaluation of therapies targeting inflammation, fibrosis and metabolic dysfunction in liver diseases. In this study, we characterized two rapid induction approaches in humanized immune system NCG mice to establish distinct models of liver fibrosis and MASH.
Methods: NCG mice engrafted with human CD34⁺ hematopoietic stem cells (HIS-NCG) were exposed either to repeated carbon tetrachloride (CCl4) administration for 23 days or to a 14-day high-fat methionine- and choline-deficient (HFMCD) diet. Liver injury was assessed through clinical monitoring, circulating ALT and LGALS3 quantification, as well as histopathological fibrosis, steatosis and human macrophage infiltration assessment in the liver.
Results: Both protocols induced rapid health deterioration associated with elevated serum ALT levels compared with control animals. However, the resulting pathological phenotypes differed substantially between models. CCl4-treated HIS-NCG mice developed severe liver fibrosis, with 88% of animals presenting bridging fibrosis (F3) or cirrhotic architecture, without associated steatosis or marked human macrophage infiltration. In contrast, the HFMCD diet induced a broader phenotype consistent with MASH, including advanced steatosis, a NAFLD activity score (NAS) of 6 and early-stage fibrosis (F0-F1), associated with infiltration by human CD68⁺ macrophages. In both models, increased α-smooth muscle actin expression, indicative of hepatic stellate cell activation, together with elevated circulating galectin-3-binding protein levels, further supported the presence of active fibrotic processes.
Conclusions: Together, these HIS models provide well-defined liver phenotype platforms for the evaluation of therapeutic candidates targeting human immune-mediated pathways involved in liver disease.