RNA interfering targeting human leukocyte antigen-G enhanced immune surveillance mediated by the natural killer cells on hepatocellular carcinoma.

BACKGROUND: Up-regulation of Human Leukocyte Antigen-G (HLA-G) expression is thought to contribute to the escape in immune surveillance by suppressing natural killer (NK) cell function. However, little is known about the expression of HLA-G in hepatocellular carcinoma (HCC) and its relationship to NK cell-mediated cytotoxicity. In this study, we aimed to investigate the expression of HLA-G in human HCC cell lines and determine whether its expression was related to inhibition of NK cell cytolysis. MATERIALS AND METHODS: The levels of HLA-G gene expression in human HCC cell lines were assessed by indirect immunofluorescence analysis (IFA), Real time RT-PCR and Western Blot. Vectors containing small interfering RNA (siRNA) specifically targeting the HLA-G gene were constructed and applied to diminish HLA-G expression. The cells were examined by flow cytometry and fluorescent microscope 24 h after transfection as well as 2-3 weeks after G418 selection. The steady-state levels of HLA-G mRNA and protein were then checked by real time RT-PCR and Western Blot analysis, respectively. A nonradioactive cytotoxicity assay was used to evaluate the effect of HLA-G on NK-mediated cytotoxicity against the siRNA treated cells. RESULTS: Both HLA-G mRNA and protein can be detected in human HCC cell lines. Levels of HLA-G mRNA and protein were diminished 88.73% and 75.91% respectively by targeting siRNA. In the stable HLA-G gene knock-down cell lines, a significant increase in NK cell-mediated lysis occurred. CONCLUSIONS: Abnormal expression of HLA-G in HCC cell lines plays an important role in protecting against NK cell attack. The significant correlation between HLA-G expression and NK cell lysis implies that the abnormal expression of HLA-G might contribute to the mechanism of escape from host immune surveillance in HCC.

[Study of embryonic stem cells induced to express hepatic cell functions in vitro in a pathologic niche containing cholestatic serum].

OBJECTIVE: To study the role of a pathologic niche inducing mouse embryonic stem cells (ESC) to express hepatic cell functions in vitro. METHODS: Embryoid bodies were developed from 5 to 7 day hanging-drop culture of mouse ESC, and their dissociated cells were planted in three differential systems: nothing added; with 20 ng/ml hepatocyte growth factor (HGF); and 5% rat cholestatic serum plus 20 ng/ml HGF added. Their differentiation was observed with inverted microscopes daily, and their hepatic functions were analyzed against their synthesis of glycogen, triglycerides, albumin, and urea nitrogen, and by their staining of indocyanine green (ICG) and fluorescein diacetate (FDA). RESULTS: ESC spontaneous differentiation was hardly being controlled to form three germ layers. HGF prompted the ESC to develop further into visceral endoderm and mesoderm (myocardium), but both of them only expressed a low level of hepatocyte-specific metabolic functions. With cholestatic serum added into the HGF-induced system, differentiated cells grew into similar angular cells, and had a higher level synthesis of glycogen, triglycerides, albumin and urea nitrogen with positive ICG and FDA staining. CONCLUSIONS: Spontaneous or HGF-induced ESC differentiation has only limited hepatic functions expressed. A pathologic niche in vitro induces ESC to develop into hepatic lineages, with a higher level of hepatic metabolic functions.

Selection, proliferation and differentiation of bone marrow-derived liver stem cells with a culture system containing cholestatic serum in vitro.

AIM: To explore the feasibility of direct separation, selective proliferation and differentiation of the bone marrow-derived liver stem cells (BDLSC) from bone marrow cells with a culture system containing cholestatic serum in vitro. METHODS: Whole bone marrow cells of rats cultured in routine medium were replaced with conditioning selection media containing 20 mL/L, 50 mL/L, 70 mL/L, and 100 mL/L cholestatic sera, respectively, after they attached to the plates. The optimal concentration of cholestatic serum was determined according to the outcome of the selected cultures. Then the selected BDLSC were induced to proliferate and differentiate with the addition of hepatocyte growth factor (HGF). The morphology and phenotypic markers of BDLSC were characterized using immunohistochemistry, RT-PCR and electron microscopy. The metabolic functions of differentiated cells were also determined by glycogen staining and urea assay. RESULTS: Bone marrow cells formed fibroblast-like but not hepatocyte-like colonies in the presence of 20 mL/L cholestatic serum. In 70 mL/L cholestatic serum, BDLSC colonies could be selected but could not maintain good growth status. In 100 mL/L cholestatic serum, all of the bone marrow cells were unable to survive. A 50 mL/L cholestatic serum was the optimal concentration for the selection of BDLSC at which BDLSC could survive while the other populations of the bone marrow cells could not. The selected BDLSC proliferated and differentiated after HGF was added. Hepatocyte-like colony-forming units (H-CFU) then were formed. H-CFU expressed markers of embryonic hepatocytes (AFP, albumin and cytokeratin 8/18), biliary cells (cytokeratin 19), hepatocyte functional proteins (transthyretin and cytochrome P450-2b1), and hepatocyte nuclear factors (HNF-1alpha and HNF-3beta). They also had glycogen storage and urea synthesis functions, two of the critical features of hepatocytes. CONCLUSION: The selected medium containing cholestatic serum can select BDLSC from whole bone marrow cells. It will be a new way to provide a readily available alternate source of cells for clinical hepatocyte therapy.