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Embryonic stem cells (ESCs), with abilities of infinite proliferation (self-renewal) and to differentiate into distinct cell types (pluripotency), show attenuated inflammatory response against cytokines or pathogens, which is recognized as a unique characteristic of ESCs compared with somatic cells. However, the underlying molecular mechanisms remain unclear, and whether the attenuated inflammatory state is involved in ESC differentiation is completely unknown. Our recent study demonstrated that macroautophagy/autophagy-related protein ATG5 inhibits the inflammatory response of mouse ESCs (MmESCs) by promoting the degradation of BTRC/β-TrCP1 and further the downregulation of NFKB/NF-κB signaling. In addition, maintenance of an attenuated inflammation status in MmESCs is required for their differentiation. In conclusion, ATG5 is a key regulator for the regulation of inflammatory response and differentiation of MmESCs.

Objective: To induce the differentiation of human bone marrow mesenchymal stem cells (HMSCs) into hepatocyte-like cells with hepatocyte growth factor (HGF) and fibroblast growth factor-4 (FGF-4) in vitro., Methods: HMSCs were induced to differentiate into hepatocyte-like cells by HGF (group B), FGF-4 (group C) and HGF+FGF-4 (group D) in vitro. Undifferentiated HMSCs and L-02 cells were used as the negative (group A) and positive (group E) controls, respectively. The changes of cell morphology were observed microscopically. The expressions of hepatic markers, alpha fetoprotein (AFP) and CK-18, were detected by immunocytochemical staining at different times after induction, and the differentiation ratios of the various groups of HMSCs were calculated on the basis of image analysis. The expressions of AFP and ALB were detected by immunofluorescence assay in each group at different times after induction, and the expressions of AFP and ALB mRNA by RT-PCR., Results: HMSCs gradually transformed into spindle-shaped, round, polygonal or irregular cells after induction. Immunocytochemical staining revealed positive AFP and CK18 expressions in groups B, C, and D after induction as well as in group E. The positive units (PU) of AFP and CK18 in group D calculated according to image analysis were significantly higher than that of groups A, B, and C. The expressions of AFP and ALB detected by immunofluorescence were both positive after induction in all groups except group A, similar to the findings of the expressions of AFP and ALB mRNA by RT-PCR., Conclusion: HMSCs can be induced to differentiate into hepatocyte-like cells by HGF, FGF-4 and their combination at certain concentrations, and the hepatocyte-like cells can express some hepatic markers such as AFP, ALB, CK18, etc. HGF+FGF-4 may achieve more effective induction of HMSC differentiation into hepatocyte-like cells, and the efficiency of HGF is greater than that of FGF-4.