Intramuscular injection of an adenoviral vector expressing hepatocyte growth factor facilitates hepatic transduction with a retroviral vector in mice

Contribution of human hematopoietic stem cells to liver repair

Immune-deficient mouse models of liver damage allow examination of human stem cell migration to sites of damage and subsequent contribution to repair and survival. In our studies, in the absence of a selective advantage, transplanted human stem cells from adult sources did not robustly become hepatocytes, although some level of fusion or hepatic differentiation was documented. However, injected stem cells did home to the injured liver tissue and release paracrine factors that hastened endogenous repair and enhanced survival. There were significantly higher levels of survival in mice with a toxic liver insult that had been transplanted with human stem cells but not in those transplanted with committed progenitors. Transplantation of autologous adult stem cells without conditioning is a relatively safe therapy. Adult stem cells are known to secrete bioactive factors that suppress the local immune system, inhibit fibrosis (scar formation) and apoptosis, enhance angiogenesis, and stimulate recruitment, retention, mitosis, and differentiation of tissue-residing stem cells. These paracrine effects are distinct from the direct differentiation of stem cells to repair tissue. In patients at high risk while waiting for a liver transplant, autologous stem cell therapy could be considered, as it could delay the decline in liver function.

Cell cycle effects resulting from inhibition of hepatocyte growth factor and its receptor c-Met in regenerating rat livers by RNA interference

Hepatocyte growth factor (HGF) and its receptor c-Met are involved in liver regeneration. The role of HGF and c-Met in liver regeneration in rat following two-thirds partial hepatectomy (PHx) was investigated using RNA interference to silence HGF and c-Met in separate experiments. A mixture of 2 c-Met-specific short hairpin RNA (ShRNA) sequences, ShM1 and ShM2, and 3 HGF-specific ShRNA, ShH1, ShH3, and ShH4, were complexed with linear polyethylenimine. Rats were injected with the ShRNA/PEI complex 24 hours before and at the time of PHx. A mismatch and a scrambled ShRNA served as negative controls. ShRNA treatment resulted in suppression of c-Met and HGF mRNA and protein compared with that in controls. The regenerative response was assessed by PCNA, mitotic index, and BrdU labeling. Treatment with the ShHGF mixture resulted in moderate suppression of hepatocyte proliferation. Immunohistochemical analysis revealed severe suppression of incorporation of BrdU and complete absence of mitosis in rats treated with ShMet 24 hours after PHx compared with that in controls. Gene array analyses indicated abnormal expression patterns in many cell-cycle- and apoptosis-related genes. The active form of caspase 3 was seen to increase in ShMet-treated rats. The TUNEL assay indicated a slight increase in apoptosis in ShMet-treated rats compared with that in controls.

CONCLUSION

The data indicated that in vivo silencing of c-Met and HGF mRNA by RNA interference in normal rats results in suppression of mRNA and protein, which had a measurable effect on proliferation kinetics associated with liver regeneration.

Hepatocyte growth factor gene therapy prevents radiation-induced liver damage

AIM: To transfer human HGF gene into the liver of rats by direct electroporation as a means to prevent radiation-induced liver damage.

METHODS: Rat whole liver irradiation model was accomplished by intra-operative approach. HGF plasmid was injected into liver and transferred by electroporation using a pulse generator. Control rats (n = 8) received electrogene therapy (EGT) vehicle plasmid and another 8 rats received HGF-EGT 100 μg 48 h before WLIR. Expression of HGF in liver was examined by RT-PCR and ELISA methods. Apoptosis was determined by TUNEL assay. Histopathology was evaluated 10 wk after whole liver irradiation.

RESULTS: Marked decrease of apoptotic cells and down-regulation of transforming growth factor-beta 1 (TGF-β1) mRNA were observed in the HGF-EGT group 2 d after liver irradiation compared to control animals. Less evidence of radiation-induced liver damage was observed morphologically in liver specimen 10 wk after liver irradiation and longer median survival time was observed from HGF-EGT group (14 wk) compared to control rats (5 wk). (P = 0.031).

CONCLUSION: For the first time it has been demonstrated that HGF-EGT would prevent liver from radiation-induced liver damage by preventing apoptosis and down-regulation of TGF-β1.

Phase 1 trial of FVIII gene transfer for severe hemophilia A using a retroviral construct administered by peripheral intravenous infusion

In a phase 1 dose escalation study, 13 subjects with hemophilia A received by peripheral intravenous infusion a retroviral vector carrying a B-domain-deleted human factor VIII (hFVIII) gene. Infusions were well tolerated. Tests for replication competent retrovirus have been negative. Polymerase chain reaction (PCR) analyses demonstrate the persistence of vector gene sequences in peripheral blood mononuclear cells in 3 of 3 subjects tested. Factor VIII was measured in serial samples using both a one-stage clotting assay and a chromogenic assay. While no subject had sustained FVIII increases, 9 subjects had FVIII higher than 1% on at least 2 occasions 5 or more days after infusion of exogenous FVIII, with isolated levels that ranged from 2.3% to 19%. Pharmacokinetic parameters of exogenous FVIII infused into subjects 13 weeks after vector infusion showed an increased half-life (T1/2; P <.02) and area under the curve (AUC, P <.04) compared with prestudy values. Bleeding frequency decreased in 5 subjects compared with historical rates. These results demonstrate that this retroviral vector (hFVIII(V)) is safe and, in some subjects, persists more than a year in peripheral blood mononuclear cells, with measurable factor VIII levels and with increased available FVIII activity (increased T1/2 and AUC) after infusion of exogenous FVIII concentrate.

Pirfenidone effectively reverses experimental liver fibrosis

BACKGROUND/AIMS

Our group has been involved in searching for different strategies to ameliorate hepatic cirrhosis. The aim of this study was to evaluate the effect of Pirfenidone in the reversion or prevention of cirrhosis experimentally induced in rats by chronic administration of CCl(4) and bile-duct ligation (BDL).

METHODS

Male cirrhotic Wistar rats (8 weeks of intoxication and then hepatotoxin was discontinued) received either oral saline or Pirfenidone at 500 mg/kg per day.

RESULTS

High levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase decreased significantly (P<0.001) in animals treated with Pirfenidone (n=11) with regard to saline-administrated animals (n=9). Prothrombin activity and bilirubins were also reduced. Computerized fibrosis index demonstrated a 70% decrease (P<0.001) along with less hydroxyproline content, reduction in activated HSC and higher active cell regeneration. A rearrangement of the parenchyma was also noted and gene expression of collagens I, III and IV, transforming growth factor beta-1, Smad-7, TIMP-1 and PAI-1 decreased considerably in treated animals. Cirrhotic rats in which CCl(4) was not discontinued displayed 40% liver fibrosis reduction. In a different cirrhosis model, 4-week BDL rats treated with the drug showed a significant 50% reduction in hepatic fibrosis (P<0.01).

CONCLUSIONS

This new drug might be useful in healing human disease.

Transduction of hepatocytes after neonatal delivery of a Moloney murine leukemia virus based retroviral vector results in long-term expression of beta-glucuronidase in mucopolysaccharidosis VII dogs

The use of Moloney murine leukemia virus (MLV)-based retroviral vectors (RV) can result in stable in vivo expression in the liver, but these vectors only transduce replicating hepatocytes. As newborn animals exhibit rapid growth, we evaluated the ability of MLV-based RV to transduce hepatocytes in neonatal dogs. I.v. injection of a beta-galactosidase-expressing RV at 3 days after birth resulted in transduction of 9% of hepatocytes. Prior treatment with human hepatocyte growth factor at 2.5 mg/kg did not increase transduction. Although cells from the spleen were also transduced with moderate efficiency, cells from other organs were not. Neonatal dogs with mucopolysaccharidosis VII (MPS VII) received an i.v.injection of an RV containing the canine beta-glucuronidase (cGUSB) cDNA. At several months after transduction, clusters of hepatocytes that expressed high levels of cGUSB were present in the liver, which probably derived from replication of transduced hepatocytes. At 6 months after transduction, serum GUSB levels were 73% that of homozygous normal dogs and were 34% of the peak values observed at 1 week. We conclude that neonatal delivery of an MLV-based RV results in stable transduction of hepatocytes in dogs. This approach could result in immediate correction in patients with an otherwise-lethal genetic deficiency.

Lipopolysaccharide potentiates the effect of hepatocyte growth factor upon replication in lung, thyroid, spleen, and colon in rats in vivo

Induction of replication may potentiate in vivo gene therapy, as some viral vectors only transduce dividing cells. Hepatocyte growth factor (HGF) increases the percentage of replicating hepatocytes to 18-fold that in normal rats, and lipopolysaccharide (LPS) modestly potentiates this effect. In this study, the effect of iv HGF upon replication in other organs was determined. HGF at 10 mg/kg resulted in replication that was < or =3-fold that of normal rats in alveolar and proximal renal tubular cells. HGF alone had no effect upon replication of epithelial cells from the bronchi, thyroid, pancreas, or colon or upon cells from the muscle, pancreatic islets, spleen, blood vessels, or thymus. HGF and LPS at 5 mg/kg resulted in replication that was 9-fold that of normal rats in alveolar cells, 25-fold in bronchial epithelial cells, 4-fold in thyroid epithelial cells, 1.5-fold in the red pulp of the spleen, and 2-fold in colonic epithelial cells. The synergistic effect may be due to the fact that LPS upregulated the HGF receptor c-met in thyroid, spleen, and colon. We conclude that iv administration of HGF alone is relatively specific for inducing hepatocyte replication and would allow selective gene transfer into the liver.

Gene transfer as an approach to treating hemophilia

Hemophilia is an X-linked bleeding diathesis caused by a deficiency of either factor VIII or factor IX. Present treatment for hemophilia involves intravenous infusion of either recombinant or plasma-derived clotting factor concentrates. Problems with this treatment method, including the expense, need for intravenous access, and risks of blood-borne disease transmission, have fueled an interest in developing a gene-transfer approach to treatment. On the basis of experience with protein concentrate therapy, it seems likely that even modest elevations in circulating levels of factor VIII or factor IX can prevent most of the mortality and much of the morbidity associated with the disease. Hemophilia has a number of advantages as a model system for working out strategies for gene transfer as an approach to the treatment of genetic diseases; these include wide latitude in choice of target tissue, a wide therapeutic window for levels of circulating factor, ease of determining therapeutic endpoints, and existence of excellent animal models of the disease. Preclinical studies over the last decade have recently culminated in the initiation of clinical trials of gene transfer for hemophilia A and B. Three trials, each using different vectors and target tissues, are presently underway, and two additional trials are in late planning stages. This report reviews the preclinical data underlying these strategies and the design of the ongoing and proposed clinical trials.

Liver cirrhosis is reverted by urokinase-type plasminogen activator gene therapy

Liver cirrhosis represents a worldwide health problem and is a major cause of mortality. Cirrhosis is the result of extensive hepatocyte death and fibrosis induced by chronic alcohol abuse and hepatitis B and C viruses. Successful gene therapy approaches to this disease may require both reversal of fibrosis and stimulation of hepatocyte growth. Urokinase-type plasminogen activator (uPA) may serve this function, as it is an initiator of the matrix proteolysis cascade and induces hepatocyte growth factor expression. In a rat cirrhosis model, a single iv administration of a replication-deficient adenoviral vector encoding a nonsecreted form of human uPA resulted in high production of functional uPA protein in the liver. This led to induction of collagenase expression and reversal of fibrosis with concomitant hepatocyte and improved liver function. Thus, uPA gene therapy may be an effective strategy for treating cirrhosis in humans.

Delivery of a retroviral vector expressing human beta-glucuronidase to the liver and spleen decreases lysosomal storage in mucopolysaccharidosis VII mice

Mucopolysaccharidosis VII (MPS VII) is caused by beta-glucuronidase (beta-gluc) deficiency and results in lysosomal storage due to the inability to degrade glycosaminoglycans. Transfer of a beta-gluc gene into the liver reduces hepatic pathology as well as storage in other organs via uptake of secreted protein. A Moloney murine leukemia-based retroviral vector expressing the human beta-gluc cDNA was injected intravascularly into MPS VII mice during hepatocyte replication, which was induced with im injection of an adenoviral vector that transiently expressed hepatocyte growth factor (Ad.CMV. HGF). This procedure resulted in transduction of approximately 1% of hepatocytes, 1% of normal liver enzyme activity, and a reduction in lysosomal storage in the liver at 3.5 months. Surprisingly, controls that received retroviral vector without HGF had transduction of nonparenchymal cells in the liver, significant levels of enzyme and RNA in the liver at 2 but not 3.5 months, and reduced lysosomal storage at 3.5 months. Transduction was also achieved in the replicating cells of the spleen, where lysosomal storage was reduced. An approach using a retroviral vector without a growth factor might temporarily reduce lysosomal storage in the liver and spleen in humans. Addition of HGF might be used to augment and prolong gene transfer.

Congenital Hemorrhagic Disorders: New Insights into the Pathophysiology and Treatment of Hemophilia

The diagnostic and treatment strategies related to hemophilia are rapidly evolving. This article focuses on some of the issues of importance. Diagnostic advances in molecular genetics are reviewed by Dr. Ginsburg in Section I, including the current state of knowledge regarding the mutations responsible for hemophilia, with reference to the potential clinical applications of DNA diagnosis and prenatal testing.

Within the area of new therapeutic approaches in hemophilia, recombinant factor VIII and factor IX concentrates, their use and availability are addressed by Dr. Lusher in Section II as well as the use of so-called “primary prophylaxis” with the aim of decreasing long-term hemophilia athropathy. The use of radionuclide synovectomy as replacement for more invasive methods is also reviewed.

Various approaches to the ongoing challenge of the management of hemophilia patients with inhibitors against factor VIII and factor IX are reviewed by Dr. Hedner in Section III, including the principles for immune tolerance induction and the use of recombinant factor VIIa to induce hemostasis in bleeding patients with inhibitors.

In Section IV, gene therapy in hemophilia is reviewed by Dr. High, who focuses on recent developments in the rapidly moving field of gene therapy for hemophilia. Three phase I trials of gene therapy for hemophilia were initiated in 1999, and additional proposed trials are currently in the regulatory review process. Certain aspects of the pathophysiology of hemophilia make it an attractive model for a gene-based approach to treatment. These include latitude in choice of target tissue, a wide therapeutic window, the availability of small and large animal models of the disease, and the ease of determining therapeutic efficacy. Since there is very little published information regarding the ongoing trials, this section reviews the approaches being used, the published pre-clinical data, and considerations affecting clinical trial design in hemophilia gene therapy.

Congenital Hemorrhagic Disorders: New Insights into the Pathophysiology and Treatment of Hemophilia

The diagnostic and treatment strategies related to hemophilia are rapidly evolving. This article focuses on some of the issues of importance. Diagnostic advances in molecular genetics are reviewed by Dr. Ginsburg in Section I, including the current state of knowledge regarding the mutations responsible for hemophilia, with reference to the potential clinical applications of DNA diagnosis and prenatal testing.

Within the area of new therapeutic approaches in hemophilia, recombinant factor VIII and factor IX concentrates, their use and availability are addressed by Dr. Lusher in Section II as well as the use of so-called “primary prophylaxis” with the aim of decreasing long-term hemophilia athropathy. The use of radionuclide synovectomy as replacement for more invasive methods is also reviewed.

Various approaches to the ongoing challenge of the management of hemophilia patients with inhibitors against factor VIII and factor IX are reviewed by Dr. Hedner in Section III, including the principles for immune tolerance induction and the use of recombinant factor VIIa to induce hemostasis in bleeding patients with inhibitors.

In Section IV, gene therapy in hemophilia is reviewed by Dr. High, who focuses on recent developments in the rapidly moving field of gene therapy for hemophilia. Three phase I trials of gene therapy for hemophilia were initiated in 1999, and additional proposed trials are currently in the regulatory review process. Certain aspects of the pathophysiology of hemophilia make it an attractive model for a gene-based approach to treatment. These include latitude in choice of target tissue, a wide therapeutic window, the availability of small and large animal models of the disease, and the ease of determining therapeutic efficacy. Since there is very little published information regarding the ongoing trials, this section reviews the approaches being used, the published pre-clinical data, and considerations affecting clinical trial design in hemophilia gene therapy.

Efficient lentiviral transduction of liver requires cell cycling in vivo

Human-immunodeficiency-virus (HIV)-based lentiviral vectors are a promising tool for in vivo gene therapy. Unlike Moloney-murine-leukaemia-based retroviruses (MLV), lentiviruses are believed to stably transduce quiescent (non-cycling) cells in various organs. No previous studies, however, have directly established the cell-cycle status of any transduced cell type at the time of vector administration in vivo. In vitro studies using wild-type HIV or HIV-based vectors have shown that, in some cases, cell-cycle activation is required for infection, even though cellular mitosis is not an absolute requirement for integration. Even if the block in reverse transcription is overcome in quiescent T cells, productive infection by HIV cannot be rescued in the absence of cell-cycle activation. The potential use of these vectors for gene therapy prompted our study, which establishes a cell-cycle requirement for efficient transduction of hepatocytes in vivo.

Lipopolysaccharide potentiates the effect of hepatocyte growth factor on hepatocyte replication in rats by augmenting AP-1 activity

The liver regenerates by replication of differentiated hepatocytes after damage or removal of part of the liver. Although several growth factors and signaling pathways are activated during regeneration, it is unclear as to which of these are essential for hepatocyte replication. We show here that low- (1 mg/kg) and high- (10 mg/kg) dose hepatocyte growth factor (HGF) induced replication of 2.1% and 11.1% of hepatocytes in rats, respectively. Lipopolysaccharide (LPS), an inducer of the acute phase response, augmented hepatocyte replication in response to low- and high-dose HGF by 4- and 2-fold, respectively. HGF alone induced moderate levels of c-Jun-N-terminal kinase (JNK) and p44/p42 mitogen-activated protein kinase (MAPK), resulting in moderate levels of AP-1-DNA binding activity. The combination of LPS + HGF increased JNK and AP-1-DNA binding activity more than levels seen with LPS or HGF alone. The activation of Stat3 that was observed after administration of LPS + HGF, but not HGF alone, could contribute to increased transcription of AP-1 components. Because phosphorylation of the c-Jun component of AP-1 by JNK increases its ability to activate transcription, the AP-1 in hepatocytes from animals treated with LPS + HGF may be more active than in rats treated with LPS or HGF alone. LPS may contribute to hepatocyte replication by potentiating the effect of HGF on the activation of both AP-1-DNA binding and transcriptional activity.