Femtosecond laser: a new intradermal DNA delivery method for efficient, long‐term gene expression and genetic immunization

A femtosecond laser beam gene transduction (SG-LBGT) system is described as a novel and efficient method of intradermal (i.d.) nonviral gene delivery in mice by permeabilizing cells utilizing femtosecond laser pulses. Using this approach, significant gene expression and efficient dermal transduction lasting for >7 months were obtained. The ability of this new DNA gene transfer method to enhance genetic vaccination was tested in BALB/C mice. A single i.d. injection of a plasmid (10 microg) containing the hepatitis B virus (HBV) surface antigen (HBsAg), followed by pulses of laser, induced high titers of HBsAg-specific antibodies lasting for >210 days and increased levels of IgG1, IgG2a, IFNgamma, and IL-4, indicating the activation of both Th1 and Th2 cells. Moreover, mice vaccinated using the SG-LBGT followed by challenge with pHBV showed increased protection against viral challenge, as detected by decreased levels of HBV DNA, suggesting an efficient Th1 effect against HBV-infected replicating cells. Tumor growth retardation was induced in vaccinated mice challenged with an HBsAg-expressing syngeneic tumor. In most of the parameters tested, administration of plasmid followed by laser application was significantly more effective and prolonged than that of plasmid alone. Tissue damage was not detected and integration of the plasmid into the host genomic DNA probably did not occur. We suggest that the LBGT method is an efficient and safe technology for in vivo gene expression and vaccination and emphasizes its potential therapeutic applications for i.d. nonviral gene delivery.

Enhanced unique pattern of hematopoietic cell mobilization induced by the CXCR4 antagonist 4F-benzoyl-TN14003

An increase in the number of stem cells in blood following mobilization is required to enhance engraftment after high-dose chemotherapy and improve transplantation outcome. Therefore, an approach that improves stem cell mobilization is essential. The interaction between CXCL12 and its receptor, CXCR4, is involved in the retention of stem cells in the bone marrow. Therefore, blocking CXCR4 may result in mobilization of hematopoietic progenitor and stem cells. We have found that the CXCR4 antagonist known as 4F-benzoyl-TN14003 (T-140) can induce mobilization of hematopoietic stem cells and progenitors within a few hours post-treatment in a dose-dependent manner. Furthermore, although T-140 can also increase the number of white blood cells (WBC) in blood, including monocytes, B cells, and T cells, it had no effect on mobilizing natural killer cells. T-140 was found to efficiently synergize with granulocyte colony-stimulating factor (G-CSF) in its ability to mobilize WBC and progenitors, as well as to induce a 660-fold increase in the number of erythroblasts in peripheral blood. Comparison between the CXCR4 antagonists T-140 and AMD3100 showed that T-140 with or without G-CSF was significantly more potent in its ability to mobilize hematopoietic stem cells and progenitors into blood. These results demonstrate that different CXCR4 antagonists may have different therapeutic potentials.

TLR3 signaling in a hepatoma cell line is skewed towards apoptosis

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPS) leading to the activation of the innate immune response and subsequently to the shaping of the adaptive immune response. Of the known human TLRs, TLR3, 7, 8, and 9 were shown to recognize nucleic acid ligands. TLR3 signaling is induced by double-stranded (ds)RNA, a molecular signature of viruses, and is mediated by the TRIF (TIR domain-containing adaptor-inducing IFNbeta) adaptor molecule. Thus, TLR3 plays an important role in the host response to viral infections. The liver is constantly exposed to a large variety of foreign substances, including pathogens such as HBV (hepatitis B virus) and HCV (hepatitis C virus), which frequently establish persistent liver infections. In this work, we investigated the expression and signaling pathway of TLR3 in different hepatoma cell lines. We show that hepatocyte lineage cells express relatively low levels of TLR3 mRNA. TLR3 signaling in HEK293 cells (human embryonic kidney cells) activated NF-kappaB and IRF3 (interferon regulatory factor 3) and induced IFNbeta (interferon beta) promoter expression, which are known to lead to pro-inflammatory cytokine secretion. In Huh7 cells, there was only a short-term IRF3 activation, and a very low level of IFNbeta expression. In HepG2 cells on the other hand, while no induction of pro-inflammatory factors was observed, signaling by TLR3 was skewed towards the induction of apoptosis. These results indicate preferential induction of the apoptotic pathway over the cytokine induction pathway by TLR3 signaling in hepatocellular carcinoma cells with potential implications for therapeutic strategies.

Functional MR imaging during hypercapnia and hyperoxia: noninvasive tool for monitoring changes in liver perfusion and hemodynamics in a rat model

PURPOSE

To prospectively assess functional magnetic resonance (MR) imaging during hypercapnia and hyperoxia for monitoring changes in liver perfusion and hemodynamics in rats.

MATERIALS AND METHODS

All experiments were performed with approval of an animal care and use committee. Functional T2*-weighted gradient-echo MR images of the rat liver were acquired during hyperoxia and graded hypercapnia (n=24). Additional images were acquired during portal vein ligation (n=4), induced hypovolemia (n=5), and 70% hepatectomy (n=5). Hypercapnic effects were confirmed with Doppler ultrasonography and with gadopentetate dimeglumine. Differences between groups were analyzed by using Wilcoxon rank sum test, except for the graded hypercapnia, for which one-way analysis of variance was used.

RESULTS

Liver signal intensity (SI) increased due to hyperoxia; the percentage change in SI was seven times greater than that in muscle tissue; this reflects higher vascularity of the liver. Liver SI decreased due to hypercapnia; the percentage change in SI was negative in the liver but positive in the muscle (P<.001). Induced hypovolemia resulted in considerable decreases in functional MR imaging response; this reflects lower liver perfusion. Clinical applicability of the functional MR imaging method was proved by monitoring changes in liver perfusion that resulted from liver resection.

CONCLUSION

In the liver, the magnitude of the percentage change in SI induced by hypercapnia and hyperoxia reflects changes in total blood volume; whereas percentage change in SI values induced by hypercapnia from a negative to a positive value reflects relative changes in portal-to-arterial blood flow ratio.

Molecular mechanisms of the chemopreventive effect on hepatocellular carcinoma development in Mdr2 knockout mice

Dietary antioxidants and selenium compounds were shown to have a therapeutic effect against hepatocellular carcinoma in several mouse models. We tested the effects of tannic acid and selenomethionine on hepatocellular carcinoma development in Mdr2 knockout (Mdr2-KO) mice. Mdr2-KO and age-matched Mdr2 heterozygous control mice were fed with tannic acid or selenomethionine during the first 3 months of life. Then, several mice from each group were sacrificed, and liver tissue samples were removed for analysis. The remaining mice were fed a regular diet until the age of 16 months, at which time the number and size of liver tumors were determined. Liver tissue samples of 3-month-old mice were subjected to gene expression profiling analysis using cDNA macroarrays containing probes for 240 genes that regulate responses to oxidative stress and inflammation or lipid metabolism. Both tannic acid and selenomethionine had partial chemopreventive effect on development of hepatocellular carcinoma in Mdr2-KO mice: they reduced the incidence of large tumor nodules (diameter >1 cm) at age 16 months. Both agents inhibited gene expression and reversed up-regulation of many genes that control inflammation or response to oxidative stress in Mdr2-KO livers at age 3 months. This inhibitory effect on gene expression correlated with the ability of agents to reduce incidence of large tumors: selenomethionine was more active than tannic acid in both aspects. Understanding the molecular mechanism of chemoprevention effect could improve our therapeutic modalities while using these agents.

Role of caspase-8 in hepatocyte response to infection and injury in mice

Caspase-8 has been implicated in signaling for apoptotic cell death and for certain nonapoptotic functions. However, knowledge of actual physiological or pathophysiological processes to which this enzyme contributes is lacking. Using a mouse model and employing the conditional knockout approach to delete the caspase-8 gene specifically in the liver, we found that caspase-8 deficiency in hepatocytes facilitates infection of the liver by Listeria monocytogenes, attenuates the hepatocyte proliferation wave during the first 48 hours after partial hepatectomy and, depending on the genetic background of the mice, prompts a chronic inflammatory response to the hepatectomy, as a result of which the proliferation of hepatocytes, although initially suppressed, might later be persistently enhanced, resulting in significant hepatomegaly.

CONCLUSION

These findings indicate that caspase-8 participates in regulation of the cellular response to infection and injury and that it does so by affecting various cellular functions, including cell death, cell proliferation, and induction of inflammation.

Replication-deficient adenovirus induces host topoisomerase I activity: implications for adenovirus-mediated gene expression

Replication-deficient adenoviruses are useful vectors for the transfer of therapeutic transgenes to malignant and non-malignant tissues. Yet their clinical application is limited by the potential toxicity of viral infection and the transient nature of transgene expression. Although transgene expression from adenovirus vectors is initially higher than expression of transgenes transduced by other viral or non-viral vectors, it is often insufficient to generate a significant therapeutic effect. We addressed this issue by searching for DNA-targeted viral-induced host responses potentially restricting transgene expression. Nuclear protein extracts from livers of rats systemically infected with replication-deficient adenovirus exhibited enhanced topoisomerase I activity compared with extracts from uninfected animals. Consequently, the inhibition of topoisomerase I by the anti-cancer drug topotecan greatly enhanced transgene expression in adenovirus-infected hepatic cells, colon cancer and prostate cancer cell cultures, mouse liver, human ex vivo tumor specimens, and mouse tumor in vivo. The enhancement could not be ascribed to non-specific genotoxic stress, cell death, or cell-cycle perturbation. These findings are significant for gene therapy as they reveal novel aspects of the host anti-adenovirus response and set the stage for the development of a rational molecular-pharmacological approach to increase the effectiveness, and safety, of adenovirus-mediated cancer therapeutics.

Clinical evaluation (Phase I) of a human monoclonal antibody against hepatitis C virus: safety and antiviral activity

BACKGROUND/AIMS

HCV-AB68, a human monoclonal antibody against the envelope protein of hepatitis C virus (HCV), neutralizes HCV in cell-culture and in the HCV-Trimera mouse model. A Phase 1 clinical trial was designed to test safety, tolerability, and antiviral activity of HCV-AB68 in patients with chronic HCV-infection.

METHODS/RESULTS

Single doses of HCV-AB68, 0.25-40 mg, administered to 15 patients were well tolerated with no moderate or serious adverse events (SAEs) reported. In six patients, HCV-RNA levels transiently decreased by 2- to 100-fold immediately following infusion and rebound to baseline in 24-48 h. Multiple doses of HCV-AB68, 10-120 mg, were administered to 25 patients. Doses were given weekly for 3 weeks, then 3x a week during the fourth week, after which patients were followed for 3 months. No drug-related SAEs were reported and no specific pattern of adverse events was evident. Eight out of 25 patients had at least a 1-log reduction and 17 had at least a 0.75-log reduction in HCV-RNA levels from baseline at one or more time points following HCV-AB68 infusion.

CONCLUSIONS

These data support the investigation of HCV-AB68 in the prevention of recurrent HCV-infection in patients who had received hepatic allografts for end-stage liver disease.

Air-Stable PbSe/PbS and PbSe/PbSexS1-xCore−Shell Nanocrystal Quantum Dots and Their Applications†

The optical properties and functionality of air-stable PbSe/PbS core-shell and PbSe/PbSexS1-x core-alloyed shell nanocrystal quantum dots (NQDs) are presented. These NQDs showed chemical robustness over months and years and band-gap tunability in the near infrared spectral regime, with a reliance on the NQD size and composition. Furthermore, these NQDs exhibit high emission quantum efficiencies of up to 65% and an exciton emission band that is narrower than that of the corresponding PbSe NQDs. In addition, the emission bands showed a peculiar energy shift with respect to the relevant absorption band, changing from a Stokes shift to an anti-Stokes shift, with an increase of the NQD diameter. The described core-shell structures and the corresponding PbSe core NQDs were used as passive Q-switches in eye-safe lasers of Er:glass, where they act as saturable absorbers. The absorber saturation investigations revealed a relatively large ground-state cross-section of absorption (sigma gs = 10(-16) - 10(-15) cm2) and a behavior of a "fast" absorber with an effective lifetime of tau eff approximately 4.0 ps is proposed. This lifetime is associated with the formation of multiple excitons at the measured pumping power. The product of sigma gs and tau eff enables sufficient Q-switching performance and tunability in the near infrared spectral regime. The amplified spontaneous emission properties of PbSe NQDs were examined under continuous illumination by a diode laser at room temperature, suitable for standard device conditions. The results revealed a relatively large gain parameter (g = 2.63 - 6.67 cm-1). The conductivity properties of PbSe NQD self-assembled solids, annealed at 200 degrees C, showed an Ohmic behavior at the measured voltages (up to 30 V), which is governed by a variable-range-hopping charge transport mechanism.

A3 adenosine receptors and mitogen-activated protein kinases in lung injury following in vivo reperfusion

INTRODUCTION

Although activation of A3 adenosine receptors attenuates reperfusion lung injury and associated apoptosis, the signaling pathway that mediates this protection remains unclear. Adenosine agonists activate mitogen-activated protein kinases, and these kinases have been implicated in ischemia/reperfusion injury; the purpose of this study was therefore to determine whether A3 adenosine receptor stimulation with reperfusion modulates expression of the different mitogen-activated protein kinases. In addition, we compared the effect of the A3 adenosine agonist IB-MECA with the newly synthesized, highly selective A3 adenosine receptor agonist MRS3558 on injury in reperfused lung.

METHOD

Studies were performed in an in vivo spontaneously breathing cat model, in which the left lower lobe of the lung was isolated and subjected to 2 hours of ischemia and 3 hours of reperfusion. The selective A3 adenosine receptor agonists IB-MECA (0.05 mg/kg, 0.1 mg/kg, or 0.3 mg/kg) and MRS3558 (0.05 mg/kg or 0.1 mg/kg) were administered before reperfusion.

RESULTS

Both A3 adenosine receptor agonists administered before reperfusion markedly (P < 0.01) attenuated indices of injury and apoptosis, including the percentage of injured alveoli, wet/dry weight ratio, myeloperoxidase activity, TUNEL (in situ TdT-mediated dUTP nick end labeling)-positive cells, and caspase 3 activity and expression. The more pronounced effects at low doses were observed with MRS3558. Increases in phosphorylated c-Jun amino-terminal protein kinase (JNK), p38, and extracellular signal-regulated kinase (ERK)1/2 levels were observed by the end of reperfusion compared with controls. Pretreatment with the A3 agonists upregulated phosphorylated ERK1/2 levels but did not modify phosphorylated JNK and p38 levels.

CONCLUSION

The protective effects of A3 adenosine receptor activation are mediated in part through upregulation of phosphorylated ERK. Also, MRS3558 was found to be more potent than IB-MECA in attenuating reperfusion lung injury. The results suggest not only that enhancement of the ERK pathway may shift the balance between cell death and survival toward cell survival, but also that A3 agonists have potential as an effective therapy for ischemia/reperfusion-induced lung injury.

CD4+CXCR4highCD69+ T Cells Accumulate in Lung Adenocarcinoma

The chemokine receptor CXCR4 is involved in the growth and metastasis of tumor cells. However, the expression of its ligand, the chemokine CXCL12, in tumors and its role in regulating the accumulation of immune cells within the tumors is not clear. Using ELISA and immunohistochemistry we found that CXCL12 is expressed in the majority of nonsmall cell lung cancer tissue sections obtained from stage IA to IIB nonsmall cell lung cancer patients undergoing operation. Histopathologic examination of these sections indicated that high CXCL12 expression correlated with increased tumor inflammation. In addition, disease recurrence rates in a subgroup of adenocarcinoma patients showed a tendency to correlate with high CXCL12 expression in the tumor. Isolation of adenocarcinoma-infiltrating immune cells demonstrated an increase in the percentage of CD4+CD69+CXCR4+ T cells as compared with normal lung tissue. About 30% of these cells expressed the regulatory T cell markers CD25high and FoxP3. The percentage of CD8 T cells within the tumor did not change, however; the percentage of NK and NK T cells was significantly reduced. In correlation with CXCR4 expression, CD4 T cells showed increased migration in response to CXCL12 compared with CD8 T cells and NK cells. Overall, these observations suggest that CXCL12 expression may influence tumor progression by shaping the immune cell population infiltrating lung adenocarcinoma tumors.

RNA interference for antiviral therapy

Silencing gene expression through a process known as RNA interference (RNAi) has been known in the plant world for many years. In recent years, knowledge of the prevalence of RNAi and the mechanism of gene silencing through RNAi has started to unfold. It is now believed that RNAi serves in part as an innate response against invading viral pathogens and, indeed, counter silencing mechanisms aimed at neutralizing RNAi have been found in various viral pathogens. During the past few years, it has been demonstrated that RNAi, induced by specifically designed double‐stranded RNA (dsRNA) molecules, can silence gene expression of human viral pathogens both in acute and chronic viral infections. Furthermore, it is now apparent that in in vitro and in some in vivo models, the prospects for this technology in developing therapeutic applications are robust. However, many key questions and obstacles in the translation of RNAi into a potential therapeutic platform still remain, including the specificity and longevity of the silencing effect, and, most importantly, the delivery of the dsRNA that induces the system. It is expected that for the specific examples in which the delivery issue could be circumvented or resolved, RNAi may hold promise for the development of gene‐specific therapeutics. Copyright © 2006 John Wiley & Sons, Ltd.

Monoclonal antibody HCV-AbXTL68 in patients undergoing liver transplantation for HCV: results of a phase 2 randomized study

A randomized, double-blind, dose-escalation study evaluated the safety and efficacy of hepatitis C virus (HCV)-Ab(XTL)68, a neutralizing, high-affinity, fully human, anti-E2 monoclonal antibody, in 24 HCV-positive patients undergoing liver transplantation. HCV-Ab(XTL)68 or placebo was administered at doses from 20-240 mg as 2-4 infusions during the first 24 hours after transplantation, followed by daily infusions for 6 days, weekly infusions for 3 weeks, and either 2 or 4 weekly infusions for 8 weeks. Serum concentrations of total anti-E2 obtained during daily infusions of 120-240 mg HCV-Ab(XTL)68 were 50-200 microg/mL above concentrations in the placebo group. Median serum concentration of HCV RNA dropped below baseline in all groups immediately after transplantation. On day 2, median change from baseline in HCV RNA was -1.8 and -2.4 log in the 120-mg and 240-mg groups, respectively, compared with -1.5 log with placebo. The difference was lost after day 7 when the dosing frequency was reduced. The coincidence of increases in anti-E2 with decreases in HCV RNA concentration indicate that the dose-related changes in HCV RNA concentration were a result of HCV-Ab(XTL)68 administration in the 120- and 240-mg groups. The overall incidence of nonfatal serious adverse events was higher with placebo (60%) vs. all active treatments combined (42%). In conclusion, HCV-Ab(XTL)68 may decrease serum concentrations of HCV RNA in patients after liver transplantation. Studies evaluating more frequent daily dosing at doses >120 mg are necessary to investigate sustained viral suppression in this population.

Prolonged transgene expression in murine salivary glands following non-primate lentiviral vector transduction

Salivary glands are an accessible organ for gene therapy, enabling expression of recombinant proteins for both exocrine and endocrine secretion. Lentivirus-based vectors have many advantages for gene therapy, including their ability to infect nondividing cells and to stably integrate into the host genome, enabling long-term transgene expression without eliciting an inflammatory immune response. In the present study, murine salivary glands were inoculated with feline immunodeficiency virus (FIV)-based lentiviral vectors expressing various reporter genes. Luciferase expression was observed as early as 24 h posttransduction, peaked at 17-21 days, and remained stable for more than 80 days. Staining with X-gal suggested that mucous acinar cells were effectively transduced. FIV vector transduction with the secreted alkaline phosphatase gene increased serum levels in treated animals for up to 45 days, and the FIV vector harboring the interferon-gamma (IFN-gamma) expression cassette induced an increase in IFN-gamma serum levels as well as in the supernatant of salivary gland explant cultures. These results demonstrate that the transduction of salivary glands with nonprimate lentiviral vectors may provide a novel and highly effective vehicle for long-term endocrine transgene expression.

IFN-gamma acts on T cells to induce NK cell mobilization and accumulation in target organs

The mechanism(s) that regulates NK cell mobilization and the significance of this process to NK cell activity are unknown. After Con A-induced hepatitis, NK cells are mobilized from the spleen and bone marrow into the periphery in an IFN-gamma-dependent fashion. Intraperitoneal administration of IFN-gamma stimulates the mobilization of NK cells into the circulation, but not their cell death or proliferation. Increased number of circulating NK cells was coupled with their accumulation in the peritoneum, liver, and tumor-bearing lung tissue. Furthermore, increased number of NK cells in the lung reduced metastasis of Lewis lung carcinoma cells (3LL cell line) resulting in significantly extended NK-dependent survival. Mobilization of NK cells was specific and required the presence of T cells. Moreover, mobilization and migration of spleen NK cells in response to IFN-gamma treatment is dependent on the chemokine receptor CXCR3. Mechanistic insights regarding the role of IFN-gamma in the regulation of NK cell mobilization and their accumulation at sites of tumor metastasis may lead to the development of novel immunotherapy for cancer.

Lentiviral vectors harboring a dual-gene system allow high and homogeneous transgene expression in selected polyclonal human embryonic stem cells

Genetic modification of human embryonic stem cells (hESCs) is highly valuable for their exploitation in basic science and therapeutic applications. Here we developed lentiviral vectors (LVs) constitutively expressing a reporter and a selectable marker to enable high and homogeneous transgene expression within polyclonal hESCs. LVs carrying GFP and a downstream puromycin resistance gene, linked by the encephalomyocarditis virus (EMCV) or poliovirus internal ribosome entry sites (IRES), allowed homogeneous GFP expression after antibiotic selection. The GFP-expression levels were higher with the EMCV IRES. We also developed dual-promoter vectors harboring a reporter and an antibiotic resistance gene under the regulation of human EF1alpha and PGK1 promoters, respectively. Optimal efficiency was obtained when: (1) the reporter cassette was upstream rather than downstream of the selectable marker cassette, (2) the puromycin rather than the neomycin resistance gene was used, (3) a 5' deletion (314 bp) was created in the PGK promoter, and (4) two copies of a 120-bp element derived from the hamster Aprt CpG island were introduced upstream of the EF1alpha promoter. In summary, we developed bicistronic and novel dual-promoter LVs that enable high and homogeneous expression of transgenes by polyclonal hESCs after antibiotic selection. These vectors may provide important tools for basic and applied research on hESCs.

Multiple adaptive mechanisms to chronic liver disease revealed at early stages of liver carcinogenesis in the Mdr2-knockout mice

Molecular events preceding the development of hepatocellular carcinoma were studied in the Mdr2-knockout (Mdr2-KO) mice. These mice lack the liver-specific P-glycoprotein responsible for phosphatidylcholine transport across the canalicular membrane. Portal inflammation ensues at an early age followed by hepatocellular carcinoma development after the age of 1 year. Liver tissue samples of Mdr2-KO mice in the early and late precancerous stages of liver disease were subjected to histologic, biochemical, and gene expression profiling analysis. In an early stage, multiple protective mechanisms were found, including induction of many anti-inflammatory and antioxidant genes and increase of total antioxidant capacity of liver tissue. Despite stimulation of hepatocyte DNA replication, their mitotic activity was blocked at this stage. In the late stage of the disease, although the total antioxidant capacity of liver tissue of Mdr2-KO mice was normal, and inflammation was less prominent, many protective genes remained overexpressed. Increased mitotic activity of hepatocytes resulted in multiple dysplastic nodules, some of them being steatotic. Expression of many genes regulating lipid and phospholipid metabolism was distorted, including up-regulation of choline kinase A, a known oncogene. Many other oncogenes, including cyclin D1, Jun, and some Ras homologues, were up-regulated in Mdr2-KO mice at both stages of liver disease. However, we found no increase of Ras activation. Our data suggest that some of the adaptive mechanisms induced in the early stages of hepatic disease, which protect the liver from injury, could have an effect in hepatocarcinogenesis at later stages of the disease in this hepatocellular carcinoma model.

Preclinical evaluation of two neutralizing human monoclonal antibodies against hepatitis C virus (HCV): a potential treatment to prevent HCV reinfection in liver transplant patients

Passive immunotherapy is potentially effective in preventing reinfection of liver grafts in hepatitis C virus (HCV)-associated liver transplant patients. A combination of monoclonal antibodies directed against different epitopes may be advantageous against a highly mutating virus such as HCV. Two human monoclonal antibodies (HumAbs) against the E2 envelope protein of HCV were developed and tested for the ability to neutralize the virus and prevent human liver infection. These antibodies, designated HCV-AB 68 and HCV-AB 65, recognize different conformational epitopes on E2. They were characterized in vitro biochemically and functionally. Both HumAbs are immunoglobulin G1 and have affinity constants to recombinant E2 constructs in the range of 10(-10) M. They are able to immunoprecipitate HCV particles from infected patients' sera from diverse genotypes and to stain HCV-infected human liver tissue. Both antibodies can fix complement and form immune complexes, but they do not activate complement-dependent or antibody-dependent cytotoxicity. Upon complement fixation, the monoclonal antibodies induce phagocytosis of the immune complexes by neutrophils, suggesting that the mechanism of viral clearance includes endocytosis. In vivo, in the HCV-Trimera model, both HumAbs were capable of inhibiting HCV infection of human liver fragments and of reducing the mean viral load in HCV-positive animals. The demonstrated neutralizing activities of HCV-AB 68 and HCV-AB 65 suggest that they have the potential to prevent reinfection in liver transplant patients and to serve as prophylactic treatment in postexposure events.

The use of the hydrodynamic HBV animal model to study HBV biology and anti-viral therapy

A simple reproducible and versatile small animal model for hepatitis B virus (HBV) infection is still unavailable. We have generated a simple transient liver-targeted transgenic mouse. Hydrodynamics tail vein injection of a head-to-tail dimer of adw HBV genome (pHBVadwHTD) into immunocompetent mice generated HBsAg and HBeAg expression in both serum and hepatocytes, followed by seroconversion. The injection of pHBVadwHTD into SCID mice generated prolonged HBsAg and HBeAg antigenemia and HBV viremia. Our results demonstrate that hydrodynamic injection of naked DNA could support the generation of HBV particles. We used this model for the assessment of anti-viral agents. Administration of our human monoclonal antibodies, HBV-Ab17(XTL) and HBV-Ab19(XTL), as well as Lamivudine (3TC) treatment suppressed HBV viremia. The model presented herein supports long and stable expression of HBV and will enable determination of various biological questions related to HBV life cycle, mutants and could enhance the development of anti-viral reagents.

Involvement of the CXCL12/CXCR4 pathway in the recovery of skin following burns

Burn wound healing is a complex process consisting of an inflammatory phase, the formation of granulation tissue, and remodeling. The role of the CXCL12/CXCR4 pathway in the recovery of skin following burns is unknown. We found that CXCL12 is similarly expressed in human, swine, and rat skin by pericyte and endothelial cells, fibrous sheet, fibroblasts, and axons. Following burns, the levels of CXCL12 were markedly increased in human burn blister fluids. One day after injury, there was a gradual increase in the expression of CXCL12 in the hair follicles and in blood vessel endothelium surrounding the burn. Three to 11 days following burns, an increased number of fibroblasts expressing CXCL12 were observed in the recovering dermis of rat, swine, and human skin. In contrast to CXCL12, CXCR4 expression was detected in proliferating epithelial cells as well as in eosinophils and mononuclear cells infiltrating the skin. In vitro, CXCL12 was expressed by primary human skin fibroblasts, but not by keratinocytes, and was stimulated by wounding a confluent cell layer of these fibroblasts. Blocking the CXCR4/CXCL12 axis resulted in the significant reduction in eosinophil accumulation in the dermis and improved epithelialization. Thus, blocking CXCR4/CXCL12 interaction may significantly improve skin recovery after burns.

Role of CXCR3 carboxyl terminus and third intracellular loop in receptor-mediated migration, adhesion and internalization in response to CXCL11

The chemokine receptor CXCR3 is predominantly expressed on activated T and natural killer (NK) cells. CXCR3 and its ligands, CXCL11, CXCL10, and CXCL9, play a major role in T-helper 1 (Th1)-dependent inflammatory responses. CXCL11 is the most dominant physiological inducer of adhesion, migration, and internalization of CXCR3. To study the role of CXCR3 carboxyl-terminus and the third intracellular (3i) loop in chemokine-mediated migration, adhesion, and CXCR3 internalization, we generated CXCR3 receptors mutated in their distal (Ser-Thr domain) or proximal (trileucine domain) membrane carboxyl terminus, and/or the third intracellular loop. We found that migration of CXCR3-expressing HEK 293 cells toward CXCL11 was pertussis toxin-dependent and required the membrane proximal carboxyl terminus of CXCR3. Internalization induced by CXCL11 and protein kinase C (PKC) activation was also regulated by the membrane proximal carboxyl terminus; however, only CXCL11-induced internalization required the LLL motif of this region. Internalization and Ca(2+) flux induced by CXCL11 were independent of the 3i loop S245, whereas migration at high CXCL11 concentrations, integrin-dependent adhesion, and actin polymerization were S245 dependent. Our findings indicate that CXCL11-dependent CXCR3 internalization and cell migration are regulated by the CXCR3 membrane proximal carboxyl terminus, whereas adhesion is regulated by the 3i loop S245. Thus, distinct conformational changes induced by a given CXCR3 ligand trigger different downstream effectors of adhesion, motility, and CXCR3 desensitization.

Phase I/II trial of intravenous NDV-HUJ oncolytic virus in recurrent glioblastoma multiforme

We undertook a Phase I/II trial in patients with apparent recurrent glioblastoma multiforme (GBM) based on imaging studies to determine the safety and tumor response of repetitive intravenous administration of NDV-HUJ, the oncolytic HUJ strain of Newcastle disease virus. The first part of the study utilized an accelerated intrapatient dose-escalation protocol with one-cycle dosage steps of 0.1, 0.32, 0.93, 5.9, and 11 billion infectious units (BIU) of NDV-HUJ (1 BIU = 1 x 10(9) EID(50) 50% egg infectious dose) followed by three cycles of 55 BIU. Virus was administered by intravenous infusion over 15 min. In the second part, patients received three cycles of 11 BIU. All patients without progressive disease were maintained with two doses of 11 BIU iv weekly. Eleven of the 14 enrolled patients (11-58 years, Karnofsky performance scale 50-90%) received treatment. Toxicity was minimal with Grade I/II constitutional fever being seen in 5 patients. Maximum tolerated dose was not achieved. Anti-NDV hemagglutinin antibodies appeared within 5-29 days. NDV-HUJ was recovered from blood, saliva, and urine samples and one tumor biopsy. One patient achieved a complete response. Intravenous NDV-HUJ is well tolerated. The findings of good tolerability and encouraging responses warrant the continued evaluation of NDV-HUJ in GBM, as well as other cancers.

Liver-targeted gene therapy by SV40-based vectors using the hydrodynamic injection method

Efficient reconstitution of defective genes in hepatocytes could be used to treat various liver and systemic diseases through gene therapy. To explore the potential of SV40-based vectors in liver gene therapy, we constructed SV/luc, an SV40 T-antigen replacement transduction vector, that was propagated on COS and COT cells, which supply the SV40 T-antigen in trans. For liver targeting, BALB/C mice were injected via the tail vein with SV/luc stocks containing 3 x 10(6) to 10(8) transducing units in a volume of 1-2 ml. Luciferase activity was monitored with a light-detection cooled charged-coupled device (CCCD) camera, which enables continuous in vivo measurement of luc expression. The SV40 vector proved to be efficient in gene delivery to the liver, leading to long-term (> or =107 days) transgene expression in hepatocytes. Optimal results were obtained with 3 x 10(6) to 3 x 10(7) transducing units. The hydrodynamic vector delivery method caused transient liver inflammatory changes, with full recovery within days. Low levels of SV40-neutralizing antibodies were detected in the sera of treated mice; however, there was no indication of vector or transgene-specific cellular immune responses. Vectors packaged in vitro, using recombinant capsid proteins and plasmid DNA, were also effective in liver transduction. These results suggest that SV40 vectors may be useful for liver gene therapy.

Human erythropoietin gene therapy for patients with chronic renal failure

Gene therapy holds a major promise. However, until now, this promise was fulfilled only in few cases, in rare genetic diseases. One very common clinical condition is anemia. Patients with anemia of chronic renal failure are treated with erythropoietin. The objective of this study was to develop a therapeutic platform for serum-secreted proteins like erythropoietin. We developed a tissue protein factory based on dermal cores (Biopump) harvested and implanted autologously. In this study, an adenovector was designed to express the human erythropoietin under the control of the cytomegalovirus (CMV) promoter. This vector transduced the harvested dermal cores ex vivo. The transduced cores were implanted, and erythropoietin and reticulocyte counts were measured. Dermal cores were harvested from 13 patients with chronic renal failure, and implantation was performed in 10. There were no significant drug-related side effects to this procedure. Erythropoietin serum levels increased significantly to therapeutic levels from day 1 after implantation reaching a peak during the first week of follow-up. The expression period was transient for up to 14 days. The rise of erythropoietin was followed by a transient significant increase in reticulocyte counts. The decrease of erythropoietin expression coincided with a significant dermal infiltrate of CD8 cytotoxic T cells. Antierythropoietin antibodies were not detected until day 90 following implantation. Implantation of dermal cores ex vivo transduced with human genes could eventually be used in the clinical setting to express therapeutic serum proteins. However, nonimmunogenic delivery system should be tested as gene vehicles.

The CCR5Delta32 allele is associated with reduced liver inflammation in hepatitis C virus infection

CCR5Delta32 is a deletion mutation in the chemokine receptor CCR5. Liver inflammatory activity was found to be significantly reduced (P = 0.005) in Jewish Israeli patients infected with the hepatitis C virus (HCV) carrying the CCR5Delta32 allele. The CCR5Delta32 allele does not alter susceptibility to HCV infection; however, it may play a role in the progression and outcome of the disease.

Activation of A3 adenosine receptors attenuates lung injury after in vivo reperfusion

BACKGROUND

A3 adenosine receptor (AR) activation worsens or protects against renal and cardiac ischemia-reperfusion (IR) injury, respectively. The aims of the current study were to examine in an in vivo model the effect of A3AR activation on IR lung injury and investigate the mechanism by which it exerts its effect.

METHODS

The arterial branch of the left lower lung lobe in intact-chest, spontaneously breathing cats was occluded for 2 h and reperfused for 3 h (IR group). Animals were treated with the selective A3 receptor agonist IB-MECA (300 microg/kg intravenously) given 15 min before ischemia or with IB-MECA as described, with pretreatment 15 min earlier with the selective A3AR antagonist MRS-1191, the nonsulfonylurea adenosine triphosphate-sensitive potassium channel-blocking agent U-37883A, or the nitric oxide synthase inhibitor N-nitro-l-arginine benzyl ester.

RESULTS

IB-MECA markedly (P < 0.01) reduced the percentage of injured alveoli (IR, 48 +/- 4%; IB-MECA, 18 +/- 2%), wet:dry weight ratio (IR, 8.2 +/- 0.4; IB-MECA, 4 +/- 2), and myeloperoxidase activity (IR, 0.52 +/- 0.06 U/g; IB-MECA, 0.17 +/- 0.04 U/g). This protective effect was completely blocked by pretreatment with the selective A3AR antagonist MRS-1191 and the adenosine triphosphate-sensitive potassium channel blocking agent U-37883A but not the nitric oxide synthase inhibitor N-nitro-l-arginine benzyl ester.

CONCLUSIONS

In the feline lung, the A3AR agonist IB-MECA confers a powerful protection against IR lung injury. This effect is mediated by a nitric oxide synthase-independent pathway and involves opening of adenosine triphosphate-sensitive potassium channels. Therefore, selective activation of A3AR may be an effective means of protecting the reperfused lung.

Activation of A3 adenosine receptor provides lung protection against ischemia-reperfusion injury associated with reduction in apoptosis

Apoptosis has been described in various models of ischemia-reperfusion (IR) injury, including lung transplantation. A3 adenosine receptor (AR) has been linked to a variety of apoptotic processes. The effect of A3AR activation on lung injury and apoptosis, following IR, has not been reported to date. In a spontaneously breathing cat model, in which the left lower lobe of the lung was isolated and subjected to 2 h of ischemia and 3 h of reperfusion, we tested the effect of IB-MECA, a selective A3AR agonist, on lung apoptosis and injury. Significant increase in the extent of apoptosis was observed following lung reperfusion. IB-MECA, administered before IR, and before or with reperfusion, markedly (p < 0.01) attenuated indices of injury and apoptosis including the percentage of injured alveoli, wet/dry weight ratio, myeloperoxidase activity, in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) positive cells, and caspase 3 activity and expression. The protective effects of IB-MECA were completely blocked by pretreatment with the selective A3AR antagonist MRS-1191. In summary, even when given after the onset of ischemia, the A3AR agonist IB-MECA conferred a powerful protection against reperfusion lung injury, which was associated with decreased apoptosis. This suggests a potentially important role for A3AR in lung IR injury.

Gene therapy platform for bone regeneration using an exogenously regulated, AAV-2-based gene expression system

Viral delivery of the therapeutic gene bone morphogenetic protein-2 (BMP-2) is a promising approach for bone regeneration. The human parvovirus adeno-associated virus (AAV) type 2 is considered one of the most encouraging viral vector systems because of its high transduction rates and biosafety ratings. Bone morphogenetic protein-2 is a highly potent osteoinductive protein, which induces bone formation in vivo and osteogenic differentiation in vitro. The exogenous regulation of BMP-2 expression in bone-regenerating sites is required to control BMP-2 protein secretion, thus promoting safe and controlled bone formation and regeneration. We have therefore constructed a dual-construct vector for the recombinant AAV (rAAV)-based recombinant human BMP-2 (rhBMP-2) gene delivery system, which is regulated by the tetracycline-sensitive promoter (TetON). Each vector was encapsidated separately, yielding two recombinant viruses. We evaluated the efficiency of rAAV-hBMP-2 to induce bone formation in ectopic and orthotopic sites. Doxycycline (Dox), an analogue of tetracycline, was orally administered to mice via their drinking water to induce rhBMP-2 expression. Bone formation was measured using quantitative imaging-microcomputerized tomography and cooled charge-coupled device imaging-to detect osteogenic activity at the cellular level, detecting osteocalcin expression. The rAAV-hBMP-2-treated mice that were given Dox demonstrated bone formation in both in vivo models compared to none in mice prevented from receiving Dox. Thus, the Tet-regulated rAAV-hBMP-2 vector is an effective means of induction and regulation of bone regeneration and repair.

Human mesenchymal stem cells alter antigen-presenting cell maturation and induce T-cell unresponsiveness

Infusion of either embryonic or mesenchymal stem cells prolongs the survival of organ transplants derived from stem cell donors and prevents graft-versus-host-disease (GVHD). An in-depth mechanistic understanding of this tolerization phenomenon could lead to novel cell-based therapies for transplantation. Here we demonstrate that while human mesenchymal stem cells (hMSCs) can promote superantigen-induced activation of purified T cells, addition of antigen-presenting cells (APCs; either monocytes or dendritic cells) to the cultures inhibits the T-cell responses. This contact- and dose-dependent inhibition is accompanied by secretion of large quantities of interleukin (IL)-10 and aberrant APC maturation, which can be partially overridden by the addition of factors that promote APC maturation (ie, lipopolysaccharide [LPS] or anti-CD40 monoclonal antibody [mAb]). Thus, our data support an immunoregulatory mechanism wherein hMSCs inhibit T cells indirectly by contact-dependent induction of regulatory APCs with T-cell-suppressive properties. Our data may reveal a physiologic phenomenon whereby the development of a distinct APC population is regulated by the tissue's cellular microenvironment.

A hepatocellular carcinoma cell line producing mature hepatitis B viral particles

Current in vitro models for hepatitis B virus (HBV) are based on human hepatoblastoma cell lines transfected with HBV genome. The objective of this work was to develop an in vitro, hepatocellular carcinoma (HCC)-based system supporting HBV full replication and producing mature viral particles. The FLC4 human HCC cell line was stably transfected with a plasmid carrying a head-to-tail dimer of the adwHBV genome. One of the clones, FLC4A10II, exhibited prolonged expression of HBV, as was demonstrated by secreted levels of HBsAg, HBeAg, and HBV DNA in the culture medium of the growing cells. Furthermore, the cells produced HBV particles that were detected by a cesium chloride density gradient performed on the culture medium. Analysis by Southern blot revealed that HBV DNA has integrated into the FLC4A10II cell genome. The presence of HBV in the FLC4A10II cells did not cause alterations in cell morphology and the cells continued to resemble mature hepatocytes. They do exhibit a high mitotic activity. The new HBV stably transfected cell line, FLC4A10II, can serve as an important tool for further exploration of HBV host-pathogen interaction, viral life cycle, and for assessing new antiviral agents.

NF-kappaB functions as a tumour promoter in inflammation-associated cancer

The causes of sporadic human cancer are seldom recognized, but it is estimated that carcinogen exposure and chronic inflammation are two important underlying conditions for tumour development, the latter accounting for approximately 20% of human cancer. Whereas the causal relationship between carcinogen exposure and cancer has been intensely investigated, the molecular and cellular mechanisms linking chronic inflammation to tumorigenesis remain largely unresolved. We proposed that activation of the nuclear factor kappaB (NF-kappaB), a hallmark of inflammatory responses that is frequently detected in tumours, may constitute a missing link between inflammation and cancer. To test this hypothesis, we studied the Mdr2-knockout mouse strain, which spontaneously develops cholestatic hepatitis followed by hepatocellular carcinoma, a prototype of inflammation-associated cancer. We monitored hepatitis and cancer progression in Mdr2-knockout mice, and here we show that the inflammatory process triggers hepatocyte NF-kappaB through upregulation of tumour-necrosis factor-alpha (TNFalpha) in adjacent endothelial and inflammatory cells. Switching off NF-kappaB in mice from birth to seven months of age, using a hepatocyte-specific inducible IkappaB-super-repressor transgene, had no effect on the course of hepatitis, nor did it affect early phases of hepatocyte transformation. By contrast, suppressing NF-kappaB inhibition through anti-TNFalpha treatment or induction of IkappaB-super-repressor in later stages of tumour development resulted in apoptosis of transformed hepatocytes and failure to progress to hepatocellular carcinoma. Our studies thus indicate that NF-kappaB is essential for promoting inflammation-associated cancer, and is therefore a potential target for cancer prevention in chronic inflammatory diseases.

Prolonged liver-specific transgene expression by a non-primate lentiviral vector

Liver-directed gene therapy has the potential for treatment of numerous inherited diseases affecting metabolic functions. The aim of this study was to evaluate gene expression in hepatocytes using feline immunodeficiency virus-based lentiviral vectors, which may be potentially safer than those based on human immunodeficiency virus. In vitro studies revealed that gene expression was stable for up to 24 days post-transduction and integration into the host cell genome was suggested by Alu PCR and Southern blot analyses. Systemic in vivo administration of viral particles by the hydrodynamics method resulted in high levels of gene expression exclusively in the liver for over 7 months whereas injection of plasmid DNA by the same method led to transient expression levels. Our studies suggest that feline immunodeficiency-based lentiviral vectors specifically transduce liver cells and may be used as a novel vehicle of gene delivery for treatment of metabolic disease.

Role of high expression levels of CXCR4 in tumor growth, vascularization, and metastasis

Hormone refractory metastatic prostate cancer remains an incurable disease. We found that high expression levels of the chemokine receptor CXCR4 correlated with the presence of metastatic disease in prostate cancer patients. Positive staining for CXCL12, the ligand for CXCR4, was mainly present in the tumor-associated blood vessels and basal cell hyperplasia. Subcutaneous xenografts of PC3 and 22Rv1 prostate tumors that overexpressed CXCR4 in NOD/SCID mice were two- to threefold larger in volume and weight vs. controls. Moreover, blood vessel density, functionality, invasiveness of tumors into the surrounding tissues, and metastasis to the lymph node and lung were significantly increased in these tumors. Neutralizing the interactions of CXCL12/CXCR4 in vivo with CXCR4 specific antibodies inhibited the CXCR4-dependent tumor growth and vascularization. In vitro, CXCL12 induced the proliferation and VEGF secretion but not migration of PC3 and 22Rv1 cells overexpressing CXCR4. Similar effects of CXCR4 overexpression on tumor growth in vivo were also noted in two breast cancer lines, suggesting that the observed effect of CXCR4 is not unique to prostate tumor cells. Thus high levels of the chemokine receptor CXCR4 induce a more aggressive phenotype in prostate cancer cells and identify CXCR4 as a potential therapeutic target in advanced cases of metastatic prostate cancer.

Oncofetal splice-pattern of the human H19 gene

H19 is an imprinted gene that demonstrates maternal monoallelic expression in fetal tissues and in some cancers, and very likely does not code for a protein. H19 is involved in the regulation of cell proliferation, embryonic growth, and differentiation through upstream and downstream cis elements that influence the expression of IGF2, a closely physically linked gene, and also through its RNA involved in metastasis and angiogenic processes. We report the identification of an alternatively spliced variant of H19 RNA that lacks part of exon 1. This variant was detected in human embryonic and placental tissues, but not in bladder or hepatocellular carcinomas. A very low level of this variant was also detected in colon carcinoma. The observed pattern of expression suggests that this splice variant is a developmentally regulated H19 gene transcript.

Involvement of the CXCL12/CXCR4 pathway in the advanced liver disease that is associated with hepatitis C virus or hepatitis B virus

Chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infection is accompanied by inflammation and fibrosis eventually leading to cirrhosis. The chemokine CXCL12 is involved in chronic inflammatory conditions. The role of the CXCL12/CXCR4 pathway in HCV- and HBV-associated liver inflammation and fibrosis was therefore studied. The levels and tissue localization of CXCL12 in liver and plasma of HCV and HBV patients were tested using immunohistochemistry and ELISA. The expression and function of CXCR4 on liver-infiltrating lymphocytes (LIL) were tested by FACS and transwell migration assays. We found that CXCL12 is expressed by bile duct epithelial cells in normal liver tissue. Bile duct proliferation and liver fibrosis in chronic HCV and HBV infection result in the anatomical re-distribution of CXCL12 in the liver. Moreover, CXCL12 is up-regulated in the endothelium of neo-blood-vessels formed in active inflammatory foci and is significantly elevated, compared with controls, in the plasma of patients with advanced liver fibrosis. Complementing these observations were others indicating that over 50% of LIL express CXCR4 and, in response to CXCL12, migrated and adhered to fibronectin. These observations suggest an important role for the CXCL12/CXCR4 pathway in recruitment and retention of immune cells in the liver during chronic HCV and HBV infection.

Differential usage of VLA-4 and CXCR4 by CD3+CD56+ NKT cells and CD56+CD16+ NK cells regulates their interaction with endothelial cells

The mechanism that regulates the preferential accumulation of NKT cells in the BM is unknown. The BM endothelium constitutively expresses selectins, the integrin ligands VCAM-1 and ICAM-1, and the chemokine CXCL12. Both NK and NKT subsets of cells exhibited similar tethering and rolling interactions on both P-selectin and E-selectin and expressed similar levels of the integrins, VLA-4 and LFA-1. Although NKT cells express higher levels of CXCR4 than NK cells, CXCL12 (the ligand for CXCR4) rapidly stimulates similar levels of adhesion of NK and NKT cells to VCAM-1 and ICAM-1. In both subsets, the arrest on VCAM-1 was dependent on high affinity VLA-4 and the homing of these cells to the BM of NOD/SCID was VLA-4-dependent. However, as opposed to the situation for NK cells, CXCL12 preferentially triggers, under shear flow, the rolling on VCAM-1 and transendothelial migration of NKT cells. Moreover, over-expression of high levels of CXCR4 on the YT NK cell line enables them to migrate in response to CXCL12. This study therefore suggests an important role for CXCR4 levels of expression and for VLA-4 in regulating the accumulation of NKT cells in the BM.

A pivotal role of cyclic AMP-responsive element binding protein in tumor progression

Tumor microenvironment controls the selection of malignant cells capable of surviving in stressful and hypoxic conditions. The transcription factor, cyclic AMP-responsive element binding (CREB) protein, activated by multiple extracellular signals, modulates cellular response by regulating the expression of a multitude of genes. Previously, we have demonstrated that two cystein residues, at the DNA binding domain of CREB, mediate activation of CREB-dependent gene expression at normoxia and hypoxia. The construction of a dominant-positive CREB mutant, insensitive to hypoxia cue (substitution of two cystein residues at position 300 and 310 with serine in the DNA binding domain) and of a dominant negative CREB mutant (addition of a mutation in serine(133)), enabled a direct assessment, in vitro and in vivo, of the role of CREB in tumor progression. In this work, we demonstrate both in vitro and in vivo that CREB controls hepatocellular carcinoma growth, supports angiogenesis, and renders resistance to apoptosis. Along with the identification, by DNA microarray, of the CREB-regulated genes in normoxia and hypoxia, this work demonstrates for the first time that in parallel to other hypoxia responsive mechanisms, CREB plays an important role in hepatocellular carcinoma tumor progression.

Hepatitis B virus enhances transduction of human hepatocytes by SV40-based vectors

BACKGROUND/AIMS

Chronic HBV infection, a world-wide epidemic, can lead to chronic hepatitis and eventually to cirrhosis and hepatocellular carcinoma. The liver poses obstacles for many available gene-transfer vectors. SV40-based vectors can transduce human hepatic and hematopoietic cells. We studied the effect of HBV on the transduction - efficiency of human hepatic cells by SV40 - based vectors.

METHODS

A SV40-vector carrying the luciferase gene, and wild-type SV40, were used to assess transduction efficiency of human HBV-positive and HBV-negative hepatic cells. Transduction efficiency was measured as luciferase activity or by T-antigen staining. To evaluate whether differences in transduction efficiency are due to cell recognition and/or nuclear transport, MHC-I receptors were measured by FACS analysis and SV40-DNA was extracted from the nuclei of transduced cells and quantified.

RESULTS

Two HBV-positive cell-lines, HepG2.2.2.15 and FLC4-A10II, were transduced significantly more efficiently than their parental HBV-negative cell-lines. Transient transfection of HuH-7 cells with the HBV genome also increased transduction efficiency. The level of MHC-I, the cellular receptor for SV40, was comparable in all the cell-lines studied. However, soon after infection with SV40, the nuclei of HepG2.2.2.15 contained >6-fold more SV40-DNA than HepG2.

CONCLUSIONS

HBV increases transduction by SV40-vectors. This is due to enhanced vector entry and/or transport into the nucleus. SV40-vectors appear to have a potential for gene therapy for the treatment of HBV infections.

Small interfering RNA inhibits hepatitis B virus replication in mice

Current therapies for chronic hepatitis B virus (HBV) infection are limited in their effect on viral gene expression and replication. Recent reports have shown that RNA interference can be induced in mammalian cells by short interfering RNA duplexes (siRNA). Here we studied the effects of an HBV-specific 21-bp siRNA targeted to the surface antigen region (HBsAg), where three major viral mRNAs overlap, on HBV gene expression and replication both in a cell culture system and in a mouse model for HBV replication. Transfection of siRNA into HepG2.2.15 cells, which constitutively produce HBV particles, caused a significant reduction in viral RNA production that was accompanied by a >80% drop in the secretion of viral HBsAg and HBeAg into the medium. The effect of RNAi was tested in vivo in a mouse model that we have developed for HBV infection, which entails hydrodynamic injection of a plasmid bearing the HBV genome into tail veins of mice. Injection of the HBV plasmid induces viral replication and generation of HBV viral particles detectable in the mouse sera. Co-injection of the HBV plasmid together with siRNA caused a significant inhibition in the level of viral transcripts, viral antigens, and viral DNA detected in the livers and sera of the treated mice relative to control animals. Results suggest that siRNA is capable of inhibiting HBV replication in vivo and thus may constitute a new therapeutic strategy for HBV infection.

Involvement of CXCR4 and IL-2 in the homing and retention of human NK and NK T cells to the bone marrow and spleen of NOD/SCID mice

Human natural killer (NK) and NK T cells play an important role in allogeneic bone marrow (BM) transplantation and graft-versus-leukemia (GVL) effect. The mechanisms by which these cells home to the BM and spleen are not well understood. Here we show that treatment of these cells with pertussis toxin and neutralizing antibodies to the chemokine receptor CXCR4 inhibited homing of the cells to the BM, but not the spleen, of NOD/SCID mice. The retention of NK and NK T cells within the spleen and BM was dependent on Galphai signaling and CXCR4 function. The chemokine receptors CXCR4 and CXCR3 are expressed predominantly on the cell surface of NK T cells. Following activation with interleukin-2 (IL-2), the levels of CXCR4 on NK and NK T cells decreased significantly. Treatment of cells with IL-2 inhibited their migration in response to CXCL12 and their homing and retention in the BM and spleen of NOD/SCID mice. In contrast to CXCR4, the expression levels of the chemokine receptor CXCR3 and the migration of cells in response to CXCL9 and CXCL10 increased after IL-2 treatment. Thus, down-regulation of CXCR4 and up-regulation of CXCR3 may direct the trafficking of cells to the site of inflammation, rather than to hematopoietic organs, and therefore may limit their alloreactive potential.

Femtosecond infrared laser-an efficient and safe in vivo gene delivery system for prolonged expression

The major advantages of "naked DNA gene therapy" are its simplicity and a low or negligible immune response. Gene delivery by DNA electroporation (EP) involves injection of DNA and the application of a brief electric pulse to enhance cellular permeability. Although EP is an efficient gene transduction technique in rodents, it requires much higher voltages (>500 V) in larger animals, and hence, in practice it would be hazardous for human patients, as it would cause serious tissue damage. To overcome the obstacles associated with EP-mediated gene delivery in vivo, we developed a new method of gene transduction that uses laser energy. The femtosecond infrared titanium sapphire laser beam was developed specifically for enhancing in vivo gene delivery without risks of tissue damage. System optimization revealed that injection of 10 micro g naked DNA into the tibial muscle of mice followed by application of the laser beam for 5 s, focused to 2 mm depth upon an area of 95 x 95 micro m(2), resulted in the highest intensity and duration of gene expression with no histological or biochemical evidence of muscle damage. We assessed the potential clinical application of LBGT technology by using it to transfer the murine erythropoietin (mEpo) gene into mice. LBGT-mediated mEpo gene delivery resulted in elevated (>22%) hematocrit levels that were sustained for 8 weeks. Gene expression following LBGT was detected for >100 days. Hence, LBGT is a simple, safe, effective, and reproducible method for therapeutic gene delivery with significant clinical potential.

Rectal immunization of mice with hepatitis A vaccine induces stronger systemic and local immune responses than parenteral immunization

Systemic (spleen cell (SPLC), serum antibodies) and intestinal mucosal (Peyer's patch cells (PPC), lamina propria lymphocytes (LPLs), coproantibodies) immune responses were compared in mice immunized with varying doses (144, 72, 36, 18 ELISA units [EU]) of HAVRIX, an alum-adsorbed killed hepatitis A virus (HAV) vaccine, delivered either intrarectally (i.r.) or intraperitoneally (i.p.) in three doses at weekly intervals. HAV-specific IgG, IgM, and IgA antibody responses were evaluated by ELISPOT and EIA and HAV-responsive lymphocytes by lymphocyte stimulation assays. Systemic IgG responses were greater in mice immunized intraperitoneally with 144, 72, and 36EU of HAVRIX, while IgM and IgA responses were greater in PPC and LPL cell populations, serum and coproantibodies of rectally immunized mice, particularly at HAVRIX doses of 36 and 18EU. Rectal immunization at lower doses (36, 18EU) also elicited strong cellular responses in all cell populations while parenteral (i.p.) vaccination, did not. Results suggest that rectal immunization may be a highly effective way of inducing both local and systemic immunity to HAV.

Molecular imaging of the skeleton: quantitative real-time bioluminescence monitoring gene expression in bone repair and development

Monitoring gene expression in vivo, noninvasively, is a critical issue in effective gene therapy systems. To date, there are no adequate molecular imaging techniques, which quantitatively monitor gene expression in vivo in skeletal development and repair. The aim of this study was to monitor gene expression in skeletal development and repair, using a real-time molecular imaging system, which quantitatively and noninvasively detects bioluminescence in vivo. Our experimental model consisted of transgenic mice harboring the luciferase marker gene under the regulation of the human osteocalcin (hOC) promoter. A new light detection cooled charge coupled device (CCCD) camera was applied to monitor luciferase expression. In vitro, mesenchymal stem cells (MSCs) isolated from bone marrow of transgenic mice exhibited hOC promoter regulation, detected by luciferase expression that correlated with their osteogenic differentiation. During development from 1 week to 1.5 years, transgenic mice exhibited transgene expression in a wide spectrum of skeletal organs, including calvaria, vertebra, tail, and limbs, reaching a peak at 1 week in most of the skeletal organs. In two skeletal repair models, bone fracture and marrow ablation, the noninvasive CCCD system revealed a peak of luciferase expression at 6 days postsurgery. All quantitative, noninvasive, real-time CCCD measurements correlated with a luciferase biochemical assay and luciferase immunohistochemistry, which demonstrated luciferase expression in hypertrophic chondrocytes and trabecular osteoblasts. Our studies show for the first time (1) the CCCD detection system is a reliable quantitative gene detection tool for the skeleton in vivo, (2) expression of luciferase regulated by the hOC promoter is significantly decreased with age in most skeletal sites, and (3) the dynamics of hOC regulation during mice skeletal development and repair in real time, quantitatively and noninvasively.

Stable genetic modification of human embryonic stem cells by lentiviral vectors

Human embryonic stem (hES) cells are pluripotent cells derived from the inner cell mass of the early preimplantation embryo. An efficient strategy for stable genetic modification of hES cells may be highly valuable for manipulating the cells in vitro and may promote the study of hES cell biology, human embryogenesis, and the development of cell-based therapies. Here, we demonstrate that vectors derived from self-inactivating (SIN) human immunodeficiency virus type 1 (HIV-1) are efficient tools for stable genetic modification of hES cells. Transduction of hES cells by a modified vector derived from SIN HIV-1 and containing the woodchuck hepatitis regulatory element (WPRE) and the central polypurine tract (cPPT) sequence facilitated stable transgene expression during prolonged (38 weeks) undifferentiated proliferation in vitro. Southern blot analysis revealed that the viral vector had integrated into the host cells' DNA. Transgene expression was maintained throughout differentiation into progeny of all three germ layers both in vitro and in vivo in teratomas. Thus, the transduced hES cells retained the capability for self-renewal and their pluripotent potential. Genetic modification of hES cells by lentiviral vectors provides a powerful tool for basic and applied research in the area of human ES cells.

The role of cytokines in liver failure and regeneration: potential new molecular therapies

The liver is a unique organ, and first in line, the hepatocytes encounter the potential to proliferate during cell mass loss. This phenomenon is tightly controlled and resembles in some way the embryonal co-inhabitant cell lineage of the liver, the embryonic hematopoietic system. Interestingly, both the liver and hematopoietic cell proliferation and growth are controlled by various growth factors and cytokines. IL-6 and its signaling cascade inside the cells through STAT3 are both significantly important for liver regeneration as well as for hematopoietic cell proliferation. The process of liver regeneration is very complex and is dependent on the etiology and extent of liver damage and the genetic background. In this review we will initially describe the clinical relevant condition, portraying a number of available animal models with an emphasis on the relevance of each one to the human condition of fulminant hepatic failure (FHF). The discussion will then be focused on the role of cytokines in liver failure and regeneration, and suggest potential new therapeutic modalities for FHF. The recent findings on the role of IL-6 in liver regeneration and the activity of the designer IL-6/sIL-6R fusion protein, hyper-IL-6, in particular, suggest that this molecule could significantly enhance liver regeneration in humans, and as such could be a useful treatment for FHF in patients.

Clinical evaluation (phase I) of a combination of two human monoclonal antibodies to HBV: safety and antiviral properties

Treatment of chronic hepatitis B virus (HBV) infection with interferon alfa and lamivudine is characterized by lack of viral clearance, loss of response, or emergence of drug-resistant mutants. Thus, new and multiple drug approaches are needed. We have developed two fully human monoclonal antibodies, directed against different epitopes of hepatitis B surface antigen (HBsAg) that bind to all major HBV subtypes. A phase I clinical study was conducted to evaluate the safety, tolerability, and efficacy of a mixture of these two monoclonal antibodies, HBV-AB(XTL). A total of 27 chronic HBV patients were enrolled. In part A of the study 15 patients in 5 cohorts received a single intravenous infusion of antibodies with doses ranging from 0.26 mg (260 IU) to 40 mg (40,000 IU). All patients completed 16 weeks of follow-up. In the second part of the study (part B), 12 patients in 4 cohorts received 4 weekly infusions of 10, 20, 40, or 80 mg each of HBV-AB(XTL) and were followed for 4 additional weeks. Administration of antibodies was well tolerated. Patients administered doses at an Ab:Ag molar ratio of 1:2 to 1:20 showed a rapid and significant decrease in HBsAg to undetectable levels, with a corresponding reduction of HBV-DNA levels. In part B, HBV-AB(XTL) induced a significant reduction in both HBsAg and HBV-DNA levels repeatedly after administration. In conclusion, these data suggest that HBV-AB(XTL) binds HBV particles and reduces serum viral titers and HBsAg levels. HBV-AB(XTL) could be combined with other monotherapies that are currently used to treat HBV carriers.