Treatment of murine fulminant hepatitis with genetically engineered endothelial progenitor cells.

BACKGROUND & AIMS: Cell therapy has been used to attenuate liver injury. Here we evaluated whether genetic engineering of either bone marrow-derived mononuclear cells (MNC) or endothelial progenitor cells (EPC) many enhance their hepatoprotective properties. METHODS: Mice with ConA-induced hepatitis or with lethal fulminant hepatitis resulting from administration of an adenovirus encoding CD40L (AdCD40L) received an intra-splenic injection of saline or 2 × 10(6) unmodified MNC or EPC or the same cells transduced ex vivo with an adenovirus expressing luciferase (MNCLUC and EPCLUC) or encoding the hepatoprotective cytokine cardiotrophin-1 (CT-1) (MNCCT-1 and EPCCT-1). We analyzed the extent of liver damage, the intensity of inflammatory reaction, and animal survival. RESULTS: Luciferase immunohistochemistry showed that after injection into the spleen, the engineered cells migrated efficiently to the damaged liver. In mice with ConA hepatitis EPCCT-1, but not other forms of cell therapy, significantly decreased serum transaminases and induced more intense histological improvement than other treatments. This superior therapeutic effect was associated with upregulation of cytoprotective molecules including IGF-I and EGF, lower expression of proinflammatory cytokines, IL-1b and TNFα, and decreased granzyme B levels. In AdCD40L-induced lethal fulminant hepatitis, EPCCT-1 also exceeded other cell therapies in attenuating the expression of proinflammatory mediators and hepatic injury enabling 35.7% survival while mortality was 100% in the other treatment groups. CONCLUSIONS: Genetic engineering of EPC to overexpress CT-1 enhances the hepatoprotective properties of EPC and constitutes a therapy that deserves consideration for acute liver failure.

Phase 1-2 pilot clinical trial in patients with decompensated liver cirrhosis treated with bone marrow-derived endothelial progenitor cells.

The aim of this nonrandomized, open label, phase 1 clinical trial was to evaluate the safety and the feasibility of the treatment with autologous bone marrow-derived endothelial progenitor cells (EPC) in decompensated liver cirrhosis. In addition, the changes in liver function and hepatic venous pressure gradient (HVPG) and their relation with the characteristics of the cellular product were analyzed. Twelve patients with Child-Pugh ≥8 liver cirrhosis underwent bone marrow harvest for ex vivo differentiation of EPC. The final product was administered through the hepatic artery in a single administration. Patients underwent clinical and radiologic follow-up for 12 months. The phenotype and the ability to produce cytokines and growth factors of the final cellular suspension were analyzed. Eleven patients were treated (feasibility 91%). No treatment-related severe adverse events were observed as consequence of any study procedure or treatment. Model for end-stage liver disease score improved significantly (P 0.042) in the first 90 days after cells administration and 5 of the 9 patients alive at 90 days showed a decreased of HVPG. There was a direct correlation between the expression of acetylated-low density lipoprotein and von Willebrand factor in the cellular product and the improvement in liver function and HVPG. The treatment with EPCs in patients with decompensated liver cirrhosis is safe and feasible and might have therapeutic potential. Patients receiving a higher amount of functionally active EPC showed an improvement of liver function and portal hypertension suggesting that the potential usefulness of these cells for the treatment of liver cirrhosis deserves further evaluation.

Interferon alpha bioactivity critically depends on Scavenger receptor class B type I function.

Scavenger receptor class B type I (SR-B1) binds pathogen-associated molecular patterns participating in the regulation of the inflammatory reaction but there is no information regarding potential interactions between SR-B1 and the interferon system. Herein, we report that SR-B1 ligands strongly regulate the transcriptional response to interferon α (IFNα) and enhance its antiviral and antitumor activity. This effect was mediated by the activation of TLR2 and TLR4 as it was annulled by the addition of anti-TLR2 or anti-TLR4 blocking antibodies. In vivo, we maximized the antitumor activity of IFNα co-expressing in the liver a SR-B1 ligand and IFNα by adeno-associated viruses. This gene therapy strategy eradicated liver metastases from colon cancer with reduced toxicity. On the other hand, genetic and pharmacological inhibition of SR-B1 blocks the clathrin-dependent interferon receptor recycling pathway with a concomitant reduction in IFNα signaling and bioactivity. This effect can be applied to enhance cancer immunotherapy with oncolytic viruses. Indeed, SR-B1 antagonists facilitate replication of oncolytic viruses amplifying their tumoricidal potential. In conclusion, SR-B1 agonists behave as IFNα enhancers while SR-B1 inhibitors dampen IFNα activity. These results demonstrate that SR-B1 is a suitable pharmacology target to enhance cancer immunotherapy based on IFNα and oncolytic viruses.

Development of Endothelial-Specific Single Inducible Lentiviral Vectors for Genetic Engineering of Endothelial Progenitor Cells.

Endothelial progenitor cells (EPC) are able to migrate to tumor vasculature. These cells, if genetically modified, can be used as vehicles to deliver toxic material to, or express anticancer proteins in tumor. To test this hypothesis, we developed several single, endothelial-specific, and doxycycline-inducible self-inactivating (SIN) lentiviral vectors. Two distinct expression cassettes were inserted into a SIN-vector: one controlled by an endothelial lineage-specific, murine vascular endothelial cadherin (mVEcad) promoter for the expression of a transactivator, rtTA2S-M2; and the other driven by an inducible promoter, TREalb, for a firefly luciferase reporter gene. We compared the expression levels of luciferase in different vector constructs, containing either the same or opposite orientation with respect to the vector sequence. The results showed that the vector with these two expression cassettes placed in opposite directions was optimal, characterized by a robust induction of the transgene expression (17.7- to 73-fold) in the presence of doxycycline in several endothelial cell lines, but without leakiness when uninduced. In conclusion, an endothelial lineage-specific single inducible SIN lentiviral vector has been developed. Such a lentiviral vector can be used to endow endothelial progenitor cells with anti-tumor properties.

Effect of nitric oxide in the differentiation of human monocytes to dendritic cells.

The aim of this work was to study the influence of nitric oxide (NO) in the differentiation of human monocytes to dendritic cells. Human monocytes from healthy donors were differentiated to immature dendritic cells in presence of GM-CSF and IL-4. Maturation of dendritic cells was achieved with GM-CSF and TNF-alpha. Nitric oxide donors (SIN-1, DEA-NO or DETA-NO) were added during differentiation of monocytes to dendritic cells and also during dendritic cells maturation. Immature dendritic cells showed a characteristic phenotype CD80+ CD1a+ HLA-DR+ CD86+ CD40+ CD14(low/-), different from adherent monocytes CD80- CD1a- HLA-DR+ CD86+ CD40- CD14++. The addition of SIN-1 the first day of monocyte differentiation reduced cell viability and increased the percentage of apoptotic immature dendritic cells. Peroxynitrite donor, SIN-1, produced more toxic effects than DEA-NO or DETA-NO. An increase in the subpopulation CD1a+ CD80+ HLADR+ of immature dendritic cells was observed when SIN-1 or DEA-NO, but not DETA-NO, was added at the beginning of monocyte culture. There was a significant reduction in the expression of TNF-alpha receptor of mature dendritic cells when SIN-1 and DEA-NO were added together GM-CSF and TNF-alpha at the beginning of maturation. The presence of SIN-1, DEA-NO or DETA-NO in maturation induced an increase of CD83+ cells. These results suggest that nitric oxide affects differentiation and maturation of dendritic cells and this effect depends on the nitric oxide donor used.

Blockade of Wnt signaling inhibits angiogenesis and tumor growth in hepatocellular carcinoma.

Aberrant activation of Wnt signaling plays an important role in hepatocarcinogenesis. In addition to direct effects on tumor cells, Wnt signaling might be involved in the organization of tumor microenvironment. In this study, we have explored whether Wnt signaling blockade by exogenous expression of Wnt antagonists could inhibit tumor angiogenesis and control tumor growth. Human Wnt inhibitory factor 1 (WIF1) and secreted frizzled-related protein 1 (sFRP1) were each fused with Fc fragment of human IgG1 to construct fusion proteins WIF1-Fc and sFRP1-Fc. The recombinant adenoviral vectors carrying WIF1-Fc and sFRP1-Fc driven by cytomegalovirus promoter were constructed. Ad-WIF1-Fc or Ad-sFRP1-Fc induced the expression and correct conformation of WIF1-Fc and sFRP1-Fc fusion proteins. These molecules caused down-regulation of E2F1, cyclin D1, and c-myc and promoted cell apoptosis in hepatocellular carcinoma cells. Treatment of established hepatocellular carcinoma tumors with Ad-WIF1-Fc and/or Ad-sFRP1-Fc resulted in significant inhibition of tumor growth and prolonged animal survival. The antineoplastic effect was associated with increased apoptosis of tumor cells, reduced microvessel density, and decreased expression of vascular endothelial growth factor and stromal cell-derived factor-1. Tube formation and migration of human microvascular endothelial cells and mouse endothelial progenitor cells (EPC) were significantly inhibited by both WIF1-Fc and sFRP1-Fc. In addition, these molecules blocked EPC differentiation and caused EPC apoptosis. Our data indicate that Wnt antagonists WIF1-Fc and sFRP1-Fc inhibit Wnt signaling and exert potent antitumor activity by increasing the apoptosis rate in tumor cells and by impairing tumor vascularization.