Mouse Model of Metabolic Dysfunction-Associated Steatotic Liver Disease with Fibrosis

Liver fibrosis is the most important predictor of adverse outcomes in metabolic dysfunction-associated steatotic liver disease (MASLD). In pre-clinical studies of MASLD, mice are the most commonly used disease model. However, in those models, liver fibrosis is difficult to induce. This protocol describes a mouse model of MASLD in which hyperphagic Ay mice are fed a diet that is high in fat and fructose, which resembles the average diet in the US. The mice develop hepatic steatosis, injury, inflammation, and fibrosis. Fibrosis progresses from pericellular, stage 1 fibrosis after 16 weeks, to bridging, stage 3 fibrosis after 12 months. These mice also develop obesity, hypertriglyceridemia, glucose intolerance, and hyperinsulinemia. This disease model replicates the liver histopathology, the hepatic gene expression alterations, and the metabolic dysfunction of the human disease. This protocol includes two methods to quantify fibrosis: histological staining of collagen by picro-sirius red, and quantification of the liver content of hydroxyproline. These methods can be used for the study of MASLD pathophysiology and for preclinical studies of potential therapies.