Abstract: Objective:To investigate the role and mechanism of the lipid inducer MDI on activated human hepatic stellate cells.Methods:Human hepatic stele cell line LX-2 cells were cultured in vitro and divided into 4 groups:control group, solvent control group, recombinant human transforming growth factor β1(TGF-β1)group and TGF-β1+MDI group.The changes of intracellular lipid droplets were detected by oil red O staining, and the relative expression levels of liver fibrosis markers Actin alpha 2 (ACTA2), collagen type Ⅰalpha 1(COLlA1)and tissue inhibitors of metalloproteinase 1 (TIMP1) were detected by real-time fluorescence quantitative PCR(RT-qPCR).The changes of mitochondria in LX-2 cells after TGF-β1/MDI intervention were observed by mitochondrial specific fluorescence probe.The expression of protein phosphatase 2A catalyzed C subunit (PP2Ac) in each group was detected by western blotting.Results:Compared with the control group and the solvent control group, LX-2 cells of TGF-β1 exhibited cell enlargement, polygonal shape and increased cytoplasm, no distinct lipid droplets were found, the number of mitochondria increased, and the mRNA expression levels of liver fibrosis markers ACTA2, COL1A1 and TIMP-1 and the PP2Ac demethylated protein expression levels increased (all P< 0.01).Compared with the TGF-β1 group, the cells in the TGF-β1+MDI group became smaller, the number of intracellular lipid droplets increased, the number of mitochondria decreased, and the mRNA expression levels of liver fibrosis markers ACTA2, COL1A1 and TIMP-1 and the PP2Ac demethylated protein expession levels decreased (all P< 0.05).Conclusion:TGF-β1 and MDI may regulate the activation of human hepatic stellate cells by regulating the PP2Ac demethylation levels, and are related to lipogenesis and number of mitochondria.