Objective To investigate the effect of adipose derived stem cells (ADSCs) on hepatic stellate cells (HSCs) in vitro and on liver fibrosis in vivo.Methods ADSCs and HSCs were isolated from adipose tissue and liver respectively in SD rats.The coculture system was set up by transwell insert.The 5th passage HSCs were cultured on the 6-well plastic plate,and ADSCs or BRLs seeded on the transwell insert.The proliferation of HSCs was tested by CCK-8 test kit.Smoothmuscle α-actin (α-SMA) expression of HSCs were tested by Western blot.Rat models of liver fibrosis was established.Rats in ADSCs treatment group were infused with ADSCs and those in control group were infused with Buffalo rat liver cells (BRLs).Liver sections were studied by immunocytochemistry.Liver hydroxyproline (Hyp) content,serum laminin (LN)and hyaluronic acid (HA) were tested,the cytokines in the culture medium were assayed.Results HSCs and ADSCs were isolated successfully.After coculture for 72 h,compared with the control group,the proliferation and activation of HSCs was inhibited by ADSCs( absorbance of each group were 2.172 ±0.107,1.424 ± 0.013,1.209 ± 0.117,F =90.605,P ＜ 0.05 ; Gray-scale values of each group were 1.4 ± 0.2,152 ± 14,258 ± 18,F =283.348,P ＜ 0.05 ),ADSCs infusion inhibits liver fibrosis in model rats ( F =77.234,65.164,58.309,all P ＜ 0.05 ).More hepatocyte growth factor(HGF) and less transforming growth factor-β1 (TGF-β1) (F=1.767,P＜0.05)and nerve growth factor (NGF) (F=2.301,P＜0.05) were secreted by ADSCs than by BRLs.Conclusions ADSCs inhibit the proliferation and activation of hepatic stellate cells.Treatment with ADSCs decreases collagen deposition in the liver and inhibits liver fibrosis.