AIM: To evaluate the efficacy of umbilical cord-derived mesenchymal stem cells(UC-MSCs) transplantation in the treatment of liver fibrosis.METHODS: Cultured human UC-MSCs were isolated and transfused into rats with liver fibrosis induced by dimethylnitrosamine(DMN). The effects of UC-MSCs transfusion on liver fibrosis were then evaluated by histopathology; serum interleukin(IL)-4 and IL-10 levels were also measured. Furthermore, Kupffer cells(KCs) in fibrotic livers were isolated and cultured to analyze their phenotype. Moreover, UC-MSCs were cocultured with KCs in vitro to assess the effects of UCMSCs on KCs’ phenotype, and IL-4 and IL-10 levels were measured in cell culture supernatants. Finally, UCMSCs and KCs were cultured in the presence of IL-4 antibodies to block the effects of this cytokine, followed by phenotypical analysis of KCs.RESULTS: UC-MSCs transfused into rats were recruited by the injured liver and alleviated liver fibrosis, increasing serum IL-4 and IL-10 levels. Interestingly, UC-MSCs promoted mobilization of KCs not only in fibrotic livers, but also in vitro. Co-culture of UC-MSCs with KCs resulted in increased production of IL-4 and IL-10. The addition of IL-4 antibodies into the coculture system resulted in decreased KC mobilization.CONCLUSION: UC-MSCs could increase IL-4 and promote mobilization of KCs both in vitro and in vivo, subsequently alleviating the liver fibrosis induced by DMN. AIM: To evaluate the efficacy of umbilical cord-derived mesenchymal stem cells (UC-MSCs) transplantation in the treatment of liver fibrosis. METHODS: Cultured human UC-MSCs were isolated and transfused into rats with liver fibrosis induced by dimethylnitrosamine (DMN). The effects of UC-MSCs on transfusion on liver fibrosis were then evaluated by histopathology; serum interleukin (IL) -4 and IL-10 levels were also measured. Furthermore, Kupffer cells (KCs) in fibrotic livers were isolated and cultured to analyze their phenotype Moreover, UC-MSCs were cultured in the presence of Cocultured with KCs in vitro to assess the effects of UCMSCs on KCs’ phenotype, and IL-4 and IL-10 levels were measured in cell culture supernatants IL-4 antibodies to block the effects of this cytokine, followed by phenotypical analysis of KCs.RESULTS: UC-MSCs transfused into rats were recruited by the injured liver and alleviated liver fibrosis, increasing serum IL-4 and IL-10 levels. Int UC-MSCs promoted mobilization of KCs not only in fibrotic livers, but also in vitro. Co-culture of UC-MSCs with KCs resulted in increased production of IL-4 and IL-10. the coculture system resulted in decreased KC mobilization. CONCLUSION: UC-MSCs could increase IL-4 and promote mobilization of KCs both in vitro and in vivo, subsequently alleviating the liver fibrosis induced by DMN.