Multipotent Adult Progenitor Cells (MAPC) contribute to hepatocarcinoma neovasculature.

The use of stem cells as a vehicle of therapeutic genes is an attractive approach for the development of new antitumoral strategies based on gene therapy. The aim of our study was to assess the potential of bone marrow-derived Multipotent Adult Progenitor Cells (rMAPCs) to differentiate in vitro and in vivo into endothelial cells and to be recruited to areas of tumor vasculogenesis. In vitro, rMAPCs obtained from Buffalo rats differentiated into cells expressing endothelial markers and demonstrated functional endothelial capacity. Intravenous injection of undifferentiated rMAPC transduced with a lentivirus expressing GFP in an orthotopic rat model of hepatocellular carcinoma, resulted in tumor recruitment of the injected cells and in vivo differentiation into endothelial cells in the tumor area with contribution to vasculogenesis. In summary, our results suggest that rMAPCs can be efficiently recruited by vascularized tumors and differentiate to endothelium and thus may represent a useful vehicle for delivery of therapeutic genes to sites of active tumor neovascularization.

IFN-alpha5 mediates stronger Tyk2-stat-dependent activation and higher expression of 2',5'-oligoadenylate synthetase than IFN-alpha2 in liver cells.

Interferon-alpha5 (IFN-alpha5) is the main IFN-alpha subtype expressed in the liver. Hepatitis C virus (HCV) infection is associated with low IFN-alpha5 mRNA levels, possibly reflecting an escape mechanism of the virus. In this work, we sought to compare IFN-alpha2 and IFN-alpha5 with respect to activation of early cell signaling cascades and induction of antiviral genes in the human hepatoma HepG2 and Huh7 cell lines. We found that the Tyr701 phosphorylation kinetics of Stat1 mediated by IFN stimulation was higher when cells were incubated with IFN-alpha5 than when using IFN-alpha2. Similarly, Tyr(1054/1055) phosphorylation kinetics of Tyk2 were more intense after exposure to IFN-alpha5 than when using IFN-alpha2. Concomitantly, Tyr705 phosphorylation of Stat3 was higher after stimulation with IFN-alpha5 than with IFN-alpha2. In parallel to these findings, the mRNA levels of the antiviral IFN-inducible gene 2',5'-oligoadenylate synthetase were higher in cell samples treated with IFN-alpha5 than with IFN-alpha2. These findings suggest that interaction of IFN-alpha5 and IFN-alpha2 subtypes with IFN type I receptor occurs differently, and this affects the intensity of expression of antiviral genes. In conclusion, our data show that in hepatocytic cells, IFN-alpha5 induces stronger signaling and higher expression of antiviral genes than IFN-alpha2. These data warrant clinical trials to evaluate the efficacy of IFN-alpha5 in chronic viral hepatitis.

Hepatitis C virus infection of primary tupaia hepatocytes leads to selection of quasispecies variants, induction of interferon-stimulated genes and NF-kappaB nuclear translocation.

Systems for in vitro culture of Hepatitis C virus (HCV) are essential tools to analyse virus-cell interactions and to investigate relevant pathophysiological aspects of HCV infection. Although the HCV replicon methodology has increased our understanding of HCV biology, this system does not reproduce the natural infection. Recently, tupaia (Tupaia belangeri chinensis) hepatocytes have been utilized for in vitro culture of HCV. In the present work, primary tupaia hepatocytes infected in vitro with HCV were used to analyse the evolution of HCV quasispecies in infected cells and the ability of the virus to influence antiviral and proinflammatory responses in cells sustaining virus replication. The results confirmed the potential of tupaia hepatocytes as a model for HCV infection, although this system is limited by rapid loss of differentiated cell phenotype in culture. These findings revealed an extraordinary plasticity of HCV quasispecies, which underwent rapid evolution to tupaia-tropic variants as early as 24 h after infection. It was also shown that HCV could activate interferon-sensitive genes, albeit modestly in comparison with other viruses such as Semliki Forest virus. Importantly, HCV activated NF-kappaB in primary hepatocytes and upregulated NF-kappaB-responsive genes including the chemokines MCP-1 and CXCL2 (MIP-2). This effect may play a role in induction of the hepatic inflammatory reaction in vivo. In summary, HCV quasispecies adapt rapidly to the specific biology of the host and HCV stimulates a blunted interferon response while inducing a proinflammatory phenotype in the infected cell.