Hepatocyte growth factor gene transfer into the liver via the portal vein using electroporation attenuates rat liver cirrhosis

Therapeutic Properties of Mesenchymal Stromal/Stem Cells: The Need of Cell Priming for Cell-Free Therapies in Regenerative Medicine

Mesenchymal stromal/stem cells (MSCs) are multipotent adult stem cells that support homeostasis during tissue regeneration. In the last decade, cell therapies based on the use of MSCs have emerged as a promising strategy in the field of regenerative medicine. Although these cells possess robust therapeutic properties that can be applied in the treatment of different diseases, variables in preclinical and clinical trials lead to inconsistent outcomes. MSC therapeutic effects result from the secretion of bioactive molecules affected by either local microenvironment or MSC culture conditions. Hence, MSC paracrine action is currently being explored in several clinical settings either using a conditioned medium (CM) or MSC-derived exosomes (EXOs), where these products modulate tissue responses in different types of injuries. In this scenario, MSC paracrine mechanisms provide a promising framework for enhancing MSC therapeutic benefits, where the composition of secretome can be modulated by priming of the MSCs. In this review, we examine the literature on the priming of MSCs as a tool to enhance their therapeutic properties applicable to the main processes involved in tissue regeneration, including the reduction of fibrosis, the immunomodulation, the stimulation of angiogenesis, and the stimulation of resident progenitor cells, thereby providing new insights for the therapeutic use of MSCs-derived products.

Human umbilical cord MSC-derived hepatocyte growth factor enhances autophagy in AOPP-treated HK-2 cells

Mesenchymal stem cell (MSC) transplantation may serve as an important treatment modality in chronic kidney disease (CKD); however, the underlying mechanisms remain unclear. Advanced oxidation protein products (AOPP) have been demonstrated to induce renal tubular epithelial cell (RTEC) injury via autophagy inhibition. Therefore, the present study was performed to investigate the role of human umbilical cord-derived MSCs (hUC-MSCs) in RTEC autophagy. AOPP-treated HK-2 cells were co-cultured with hUC-MSCs or treated with recombinant humanized hepatocyte growth factor (HGF). Western blotting was used to detect the levels of autophagy-and PI3K/AKT/mTOR signaling pathway-related proteins, and immunofluorescence staining was used to detect the levels of autophagy-related proteins. The HGF protein levels in HK-2 cells and the hUC-MSC co-culture system were measured. The cells were subsequently treated with tivantinib, an HGF competitive inhibitor, and the levels of autophagy-related proteins were detected. Microtubule-associated protein 1 light chain 3B (LC3B) II/LC3B I (LC3II/LC3I) and beclin 1 protein levels were increased, while p62, PI3K, phosphorylated (p)-AKT and the p-mTOR protein levels were decreased in AOPP-treated HK-2 cells co-cultured with hUC-MSC, compared with the group treated with AOPP only. Furthermore, HGF expression was increased in AOPP-treated HK-2 cells co-cultured with hUC-MSC, compared with the group treated with AOPP alone. When HGF activity was inhibited using tivantinib, these effects on LC3II/LC3I, beclin 1, p62, PI3K, p-AKT, and p-mTOR expression were partially reversed. Furthermore, the effects of tivantinib were reversed by Ly294002. In conclusion, the present study revealed that hUC-MSCs partially reversed AOPP-mediated inhibition of autophagy in HK-2 cells via secretion of HGF, indicating that hUC-MSCs may serve as a potential therapy for preventing the progression of CKD.

Glomeruli or interstitium targeted by inter-renal injections supplemented by electroporation: Still a useful tool in renal research

BACKGROUND

Studies concerning proteins are always a crucial part of renal research. As a result of current technologies, scientists have mastered several techniques for generating genetically modified animals. However, in most cases, accessing these animals is still time-consuming and often expensive. This makes the alteration of protein expression by in vivo plasmid transfection an easily-accessible alternative. However, there is still no comprehensive study describing where plasmids would be expressed when they are injected into the kidneys.

METHODS

We injected pEGFP-N1 into rats via intra-/inter-renal channels and detected green fluorescent protein (GFP) by immunohistochemistry and immunofluorescence to localize plasmid expression.

RESULTS

Seven days post-injection, we found that GFP was expressed in the glomeruli when pEGFP-N1 was injected via the renal artery or vein enhanced by electroporation and in the interstitium following injection via the ureter. Other channels, including intraperitoneal, subcapsule and parenchymal injection, only led to scattered expression within the kidneys.

CONCLUSIONS

The present study provides evidence that plasmid transfection via the renal vessels is suitable for glomeruli research and that transfection via the ureter is appropriate for studies regarding interstitium lesions. Additionally, we provide evidence that plasmid transfection on live animals is still an applicable and useful tool, as well as being cost-effective and facile.

A synthetic biology-based device prevents liver injury in mice

BACKGROUND & AIMS

The liver performs a panoply of complex activities coordinating metabolic, immunologic and detoxification processes. Despite the liver's robustness and unique self-regeneration capacity, viral infection, autoimmune disorders, fatty liver disease, alcohol abuse and drug-induced hepatotoxicity contribute to the increasing prevalence of liver failure. Liver injuries impair the clearance of bile acids from the hepatic portal vein which leads to their spill over into the peripheral circulation where they activate the G-protein-coupled bile acid receptor TGR5 to initiate a variety of hepatoprotective processes.

METHODS

By functionally linking activation of ectopically expressed TGR5 to an artificial promoter controlling transcription of the hepatocyte growth factor (HGF), we created a closed-loop synthetic signalling network that coordinated liver injury-associated serum bile acid levels to expression of HGF in a self-sufficient, reversible and dose-dependent manner.

RESULTS

After implantation of genetically engineered human cells inside auto-vascularizing, immunoprotective and clinically validated alginate-poly-(L-lysine)-alginate beads into mice, the liver-protection device detected pathologic serum bile acid levels and produced therapeutic HGF levels that protected the animals from acute drug-induced liver failure.

CONCLUSIONS

Genetically engineered cells containing theranostic gene circuits that dynamically interface with host metabolism may provide novel opportunities for preventive, acute and chronic healthcare.

LAY SUMMARY

Liver diseases leading to organ failure may go unnoticed as they do not trigger any symptoms or significant discomfort. We have designed a synthetic gene circuit that senses excessive bile acid levels associated with liver injuries and automatically produces a therapeutic protein in response. When integrated into mammalian cells and implanted into mice, the circuit detects the onset of liver injuries and coordinates the production of a protein pharmaceutical which prevents liver damage.

Therapeutic effect of hepatocyte growth factor-secreting mesenchymal stem cells in a rat model of liver fibrosis

Bone marrow-derived mesenchymal stromal cells (MSCs) have been reported to be beneficial for the treatment of liver fibrosis. Here, we investigated the use of genetically engineered MSCs that overexpress hepatocyte growth factor (HGF) as a means to improve their therapeutic effect in liver fibrosis. Liver fibrosis was induced by intraperitoneal injection of dimethylnitrosamine. HGF-secreting MSCs (MSCs/HGF) were prepared by transducing MSCs with an adenovirus carrying HGF-encoding cDNA. MSCs or MSCs/HGF were injected directly into the spleen of fibrotic rats. Tissue fibrosis was assessed by histological analysis 12 days after stem cell injection. Although treatment with MSCs reduced fibrosis, treatment with MSCs/HGF produced a more significant reduction and was associated with elevated HGF levels in the portal vein. Collagen levels in the liver extract were decreased after MSC/HGF therapy, suggesting recovery from fibrosis. Furthermore, liver function was improved in animals receiving MSCs/HGF, indicating that MSC/HGF therapy resulted not only in reduction of liver fibrosis but also in improvement of hepatocyte function. Assessment of cell and biochemical parameters revealed that mRNA levels of the fibrogenic cytokines PDGF-bb and TGF-β1 were significantly decreased after MSC/HGF therapy. Subsequent to the decrease in collagen, expression of matrix metalloprotease-9 (MMP-9), MMP-13, MMP-14 and urokinase-type plasminogen activator was augmented following MSC/HGF, whereas tissue inhibitor of metalloprotease-1 (TIMP-1) expression was reduced. In conclusion, therapy with MSCs/HGF resulted in an improved therapeutic effect compared with MSCs alone, probably because of the anti-fibrotic activity of HGF. Thus, MSC/HGF represents a promising approach toward a cell therapy for liver fibrosis.

Influence of Mesenchymal Stem Cells Transplantation on Regeneration Activity of Cirrhotic Liver

The efficacy of mesenchymal stem cells transplantation on regeneration activity of cirrhotic liver was evaluated in an animal model of cirrhotic liver. Autologous stem cells were obtained from bone marrow. Transplantation was performed 1 week after surgery by introducing stem cells into the liver. Immunohistochemical staining (proliferative activity, myofibroblast activation and sinusoidal capillarization) was evaluated to assess the efficacy of transplantation. It was found that, 2 months after stem cell transplantation, the severity of perisinusoidal fibrosis, inflammation of the liver and the number of myofibroblasts were reduced. Stem cell transplantation may be one of the new treatment modalities for cirrhotic liver.

How to cite this article: Maksud AR, Gennadiyevich PA, Elkhan JR. Influence of Mesenchymal Stem Cells Transplantation on Regeneration Activity of Cirrhotic Liver. Euroasian J Hepato-Gastroenterol 2014;4(2):83-86.

Therapeutic effects of hepatocyte growth factor-overexpressing human umbilical cord blood-derived mesenchymal stem cells on liver fibrosis in rats

Fibrosis is a common end stage for a variety of liver diseases, including most chronic liver diseases, and results from an imbalance between collagen deposition and degradation. Mesenchymal stem cells (MSCs) have the ability to migrate into fibrotic livers and differentiate into hepatocytes. Hepatocyte growth factor (HGF) has potent anti-apoptotic and mitogenic effects on hepatocytes during liver injury and plays an essential role in the development and regeneration of the liver. In this study, human HGF-overexpressing human umbilical cord blood-derived MSCs (hHGF-HUCB-MSCs) were prepared using the pMEX Expression System, and the upregulation of hHGF expression was confirmed by RT-PCR and ELISA. HGF expressed by hHGF-HUCB-MSCs exerted a stimulatory effect on hepatocyte proliferation in vitro. hHGF-HUCB-MSCs were transplanted to investigate the therapeutic effects of these cells on carbon tetrachloride (CCL4)-induced liver fibrosis in a rat model. After 4 weeks of cell treatment once per week with 2 × 10(6) cells, biochemical analysis of the serum and histopathological analysis of the liver tissue were performed. The results of the biochemical analysis of the serum show that the hHGF-HUCB-MSC-treated group had higher levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, indicating the improvement of liver function. Histopathology showed that the hHGF-HUCB-MSC-treated group had reduction in the density of collagen fibres. Thus hHGF-HUCB-MSCs can enhance liver regeneration and could be useful for the treatment of patients with liver fibrosis or cirrhosis.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Peroxisome proliferator-activated receptor-γ cross-regulation of signaling events implicated in liver fibrogenesis

Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear receptor with transcriptional activity controlling multiple physical and pathological processes. Recently, PPARγ has been implicated in the pathogenesis of liver fibrosis. Its depleted expression has strong associations with the activation and transdifferentiation of hepatic stellate cells, the central event in liver fibrogenesis. Studies over the past decade demonstrate that PPARγ cross-regulates a number of signaling pathways mediated by growth factors and adipokines, and cellular events including apoptosis and senescence. These signaling and cellular events and their molecular interactions with PPARγ system are profoundly involved in liver fibrogenesis. We critically summarize these mechanistic insights into the PPARγ regulation in liver fibrogenesis based on the updated findings in this area. We conclude with a discussion of the impacts of these discoveries on the interpretation of liver fibrogenesis and their potential therapeutic implications. PPARγ activation could be a promising strategy for antifibrotic therapy.

Combinatorial gene therapy renders increased survival in cirrhotic rats

Background

Liver fibrosis ranks as the second cause of death in México's productive-age population. This pathology is characterized by acummulation of fibrillar proteins in hepatic parenchyma causing synthetic and metabolic disfunction. Remotion of excessive fibrous proteins might result in benefit for subjects increasing survival index. The goal of this work was to find whether the already known therapeutical effect of human urokinase Plasminogen Activator and human Matrix Metalloprotease 8 extends survival index in cirrhotic animals.

Methods

Wistar rats (80 g) underwent chronic intoxication with CCl₄: mineral oil for 8 weeks. Cirrhotic animals were injected with a combined dose of Ad-delta-huPA plus Ad-MMP8 (3 × 10¹¹ and 1.5 × 10¹¹ vp/Kg, respectively) or with Ad-beta-Gal (4.5 × 10¹¹) and were killed after 2, 4, 6, 8 and 10 days. Then, liver and serum were collected. An additional set of cirrhotic animals injected with combined gene therapy was also monitored for their probability of survival.

Results

Only the cirrhotic animals treated with therapeutical genes (Ad-delta-huPA+Ad-MMP-8) showed improvement in liver fibrosis. These results correlated with hydroxyproline determinations. A significant decrement in alpha-SMA and TGF-beta1 gene expression was also observed. Cirrhotic rats treated with Ad-delta-huPA plus Ad-MMP8 had a higher probability of survival at 60 days with respect to Ad-beta-Gal-injected animals.

Conclusion

A single administration of Ad-delta-huPA plus Ad-MMP-8 is efficient to induce fibrosis regression and increase survival in experimental liver fibrosis.

Electroporation and ultrasound enhanced non-viral gene delivery in vitro and in vivo

Non-viral vectors are less efficient than the use of viral vectors for delivery of genetic material to cells in vitro and especially in vivo. However, viral vectors involve the use of foreign proteins that can stimulate both the innate and acquired immune response. In contrast, plasmid DNA can be delivered without carrier proteins and is non-immunogenic. Plasmid gene delivery can be enhanced by the use of physical methods that aid the passage of the plasmid through the cell membrane. Electroporation and microbubble-enhanced ultrasound are two of the most effective physical delivery methods and these can be applied to a range of different cell types in vitro and a broad range of tissues in vivo. Both techniques also have the advantage that, unlike viral vectors, they can be used to target specific tissues with systemic delivery. Although electroporation is often the more efficient of the two, microbubble-enhanced ultrasound causes less damage and is less invasive. This review provides an introduction to the methodology and summarises the range of cells and tissues that have been genetically modified using these techniques.

Liver- and lobe-specific gene transfer following the continuous microinstillation of Plasmid DNA onto the liver surface in mice: effect of instillation speed

Development of technology to deliver foreign gene(s) to a specific organ/tissue is one of the major challenges in gene therapy. Here, we show liver- and lobe-specific gene transfer following the continuous microinstillation of plasmid DNA (pDNA) onto the liver surface in mice. Naked pDNA was continuously instilled onto the right medial liver lobe using syringe pump in male ddY mice. Our previous studies showed liver- and lobe-selective gene expression after instillation of 30 mul of pDNA solution onto the liver surface, but gene expression was also found in the other liver lobe, kidney and spleen. To improve target site selectivity of gene expression, the instillation volume was decreased; however, non-specific gene expression in the other liver lobe and diaphragm was still detected. To prevent immediate diffusion of the pDNA solution, we performed continuous microinstillation of pDNA using a syringe pump; as a result, target site selectivity was greatly improved. As for instillation speed, 5 min infusion was enough to prevent diffusion of pDNA solution. Furthermore, transfection efficiency in the target site was maintained when instillation speed was slowed. Wiping off residual pDNA solution from the applied liver lobe resulted in a further improvement in selectivity, suggesting not only immediate diffusion, but also gradual diffusion, are important factors for successful target site-specific gene transfer. Information in this study will be useful for further development of an effective gene delivery system targeted to a specific organ/tissue by use of other non-viral or viral vectors.

Urokinase-type plasminogen activator increases hepatocyte growth factor activity required for skeletal muscle regeneration

The plasminogen system plays a crucial role in the repair of a variety of tissues, including skeletal muscle. We hypothesized that urokinase-type plasminogen activator (uPA) promotes muscle regeneration by activating hepatocyte growth factor (HGF), which, in turn, stimulates proliferation of myoblasts required for regeneration. In our studies, levels of active HGF and phosphorylation of the HGF receptor c-met were increased after muscle injury in wild-type mice. Compared with wild-type animals, mice deficient in uPA (uPA(-/-)) had markedly reduced HGF levels and c-met activation after muscle damage. This reduced HGF activity in uPA(-/-) animals was associated with decreased cell proliferation, myoblast accumulation, and new muscle fiber formation. On the other hand, HGF activity was enhanced at early time points in PAI-1(-/-) mice compared with wild-type mice and the PAI-1(-/-) animals exhibited accelerated muscle fiber regeneration. Furthermore, administration of exogenous uPA rescued HGF levels and muscle regeneration in uPA(-/-) mice, and an HGF-blocking antibody reduced HGF activity and muscle regeneration in wild-type mice. We also found that uPA promotes myoblast proliferation in vitro through its proteolytic activity, and this process was inhibited by an HGF-blocking antibody. Together, our findings demonstrate that uPA promotes muscle regeneration through HGF activation and subsequent myoblast proliferation.

Translational research to identify clinical applications of hepatocyte growth factor

Hepatocyte growth factor (HGF), originally purified from the plasma of patients with fulminant hepatic failure, has been shown to carry out various physiological functions. HGF not only stimulates liver regeneration, but also acts as an antiapoptotic factor in in vivo experimental models. Therefore, HGF is a promising therapeutic agent for the treatment of fatal liver diseases, including fulminant hepatic failure. After performing a number of preclinical tests, our group began an investigator-initiated registered phase I/II clinical trial of patients with fulminant hepatic failure to examine the safety and clinical efficacy of recombinant human HGF. In this article, we will discuss the basic research results as well as the translational research that underpins current attempts to use HGF in various clinical settings.

Translational research on HGF: A phase I/II study of recombinant human HGF for the treatment of fulminant hepatic failure

Hepatocyte growth factor (HGF) is a potential therapeutic agent for fatal liver diseases, including fulminant hepatic failure (FHF). After performing a number of preclinical tests with recombinant human HGF (rh-HGF), we started a phase I/II study in September 2005 of patients with FHF or late-onset hepatic failure (LOHF), to examine the safety and clinical efficacy of rh-HGF. We first administered rh-HGF (0.6 mg/m(2)/day) for 13 days to a 67-year-old Japanese man with FHF. All data from this patient were reviewed by the independent data monitoring committee, and the safety of rh-HGF was recognized. Finally, a clinical trial of rh-HGF was approved to be continued. As of August 2007, we have administered rh-HGF to four patients with FHF or LOHF. All patients showed a moderate decrease in systolic blood pressure during rh-HGF administration, while the urinary excretion of albumin did not increase in all cases. In the first and third patients, hepatic failure gradually progressed, and they died 66 and 29 days, respectively, after encephalopathy occurred. The second and fourth patients are presently still alive. In conclusion, we started a clinical trial that examined the effects of rh-HGF in patients with FHF or LOHF, and in the four patients with FHF or LOHF enrolled in this study, repeated doses of rh-HGF did not produce any severe side effects.

Reduction of fibrosis in a rat model of non-alcoholic steatohepatitis cirrhosis by human HGF gene transfection using electroporation

BACKGROUND AND AIM

To study the histological changes caused by transfection of the hepatocyte growth factor (HGF) gene using electroporation (EP) in a non-alcoholic steatohepatitis (NASH) cirrhotic liver model.

METHODS

NASH cirrhotic livers were prepared by administering a choline-deficient diet to 5-week-old male Wister rats for 12 weeks. Three groups of rats were used: rats in the G(+) group were transfected with the GFP gene using EP, rats in the H(+) group were transfected with the HGF gene using EP, and rats in the H(-) group were only injected with the HGF gene. Rats were sacrificed 2 days after gene transfection, and the Azan positive rate (APR) and Sudan positive rate (SPR) were calculated to evaluate fibrosis and fatty changes.

RESULTS

The APR of the NASH cirrhotic livers was significantly higher than that in the normal livers. The APR did not decrease in the G(+) group and the H(-) group, but decreased significantly in the nonelectroporated as well as electroporated areas of the H(+) group. For SPR, there were no significant differences between the G(+), H(-), and H(+) groups.

CONCLUSION

The improvement of fibrosis was not significant when a direct injection of the HGF gene was used alone, but it was enhanced by the concomitant use of EP. However, no efficacy was observed in fat components. These findings suggest that transfection of the HGF gene by EP may lead to an improvement of irreversible cirrhotic livers to reversible fatty livers.

Liver cirrhosis

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury, which leads to portal hypertension and end-stage liver disease. Recent advances in the understanding of the natural history and pathophysiology of cirrhosis, and in treatment of its complications, have resulted in improved management, quality of life, and life expectancy of patients. Liver transplantation remains the only curative option for a selected group of patients, but pharmacological treatments that can halt progression to decompensated cirrhosis or even reverse cirrhosis are currently being developed. This Seminar focuses on the diagnosis, complications, and management of cirrhosis, and new clinical and scientific developments.

Liver cirrhosis

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury, which leads to portal hypertension and end-stage liver disease. Recent advances in the understanding of the natural history and pathophysiology of cirrhosis, and in treatment of its complications, have resulted in improved management, quality of life, and life expectancy of patients. Liver transplantation remains the only curative option for a selected group of patients, but pharmacological treatments that can halt progression to decompensated cirrhosis or even reverse cirrhosis are currently being developed. This Seminar focuses on the diagnosis, complications, and management of cirrhosis, and new clinical and scientific developments.

Gene therapy for hepatic fibrosis

Hepatic fibrosis is a common pathological process of chronic liver diseases, characterized by increased synthesis and relatively low degradation of extracellular matrix (ECM) resulting from their dynamic imbalance. Recent progress in molecular biology techniques has made it possible to treat hepatic fibrosis with gene therapy. At present, the commonly used method is to induce the expression of exogenous genes by transducing enough therapeutic genes into injured liver to delay or cure liver fibrosis.

In situ bipolar electroporation for localized cell loading with reporter dyes and investigating gap junctional coupling

Electroporation is generally used to transfect cells in suspension, but the technique can also be applied to load a defined zone of adherent cells with substances that normally do not permeate the plasma membrane. In this case a pulsed high-frequency oscillating electric field is applied over a small two-wire electrode positioned close to the cells. We compared unipolar with bipolar electroporation pulse protocols and found that the latter were ideally suited to efficiently load a narrow longitudinal strip of cells in monolayer cultures. We further explored this property to determine whether electroporation loading was useful to investigate the extent of dye spread between cells coupled by gap junctions, using wild-type and stably transfected C6 glioma cells expressing connexin 32 or 43. Our investigations show that the spatial spread of electroporation-loaded 6-carboxyfluorescein, as quantified by the standard deviation of Gaussian dye spread or the spatial constant of exponential dye spread, was a reliable approach to investigate the degree of cell-cell coupling. The spread of reporter dye between coupled cells was significantly larger with electroporation loading than with scrape loading, a widely used method for dye-coupling studies. We conclude that electroporation loading and dye transfer is a robust technique to investigate gap-junctional coupling that combines minimal cell damage with accurate probing of the degree of cell-cell communication.

Hepatocyte growth factor: a regenerative drug for acute hepatitis and liver cirrhosis

Liver cirrhosis is a major cause of morbidity worldwide and is characterized by the loss of hepatocytes with interstitial fibrosis. In this review, we discuss the potential uses of hepatocyte growth factor for treating hepatic diseases, focusing on the molecular mechanisms whereby hepatocyte growth factor reverses liver cirrhosis. Hepatic myofibroblasts play a central role in the development of liver cirrhosis, while myofibroblasts acquire c-Met. Using a rat model of liver cirrhosis, we recently delineated the direct effect of hepatocyte growth factor toward myofibroblasts: the induction of apoptotic cell death associated with matrix degradation, the inhibition of overproliferation and the suppression of transforming growth factor-beta1 production in myofibroblasts. Hepatocyte growth factor elicits mitogenic, anti-apoptotic and anti-inflammatory functions in hepatocytes, therefore contributing to reversing liver dysfunction. Considering the insufficient production of hepatocyte growth factor is responsible for the manifestation of chronic hepatitis, supplementation with or reinduction of hepatocyte growth factor represents a new strategy for attenuating intractable liver diseases.

Liver transduction with a simian virus 40 vector encoding insulin-like growth factor I reduces hepatic damage and the development of liver cirrhosis

Liver transplantation is the only treatment for advanced liver cirrhosis. Therapies halting the progression of the disease are urgently needed. Administration of recombinant insulin-like growth factor-I (rIGF-I) induces hepatoprotective effects in experimental cirrhosis. Therefore, we analyzed the efficacy of a recombinant simian virus 40 vector (rSV40) encoding IGF-I (rSVIGF-I) to prevent cirrhosis progression. First, transgene expression was evaluated in mice injected with rSV40 encoding luciferase, which showed long-term hepatic expression of the transgene. Interestingly, luciferase expression increased significantly in CCl(4)-damaged livers and upon IGF-I administration, thus liver injury and IGF-I expression from rSVIGF-I should favor transgene expression. rSVIGF-I therapeutic efficacy was studied in rats where liver cirrhosis was induced by CCl(4) inhalation during 36 weeks. At the end of the study, the hepatic levels of IGF-I and IGF-binding protein 3 were higher in rSVIGF-I-treated rats than in control cirrhotic animals. Cirrhotic rats treated with rSVIGF-I had reduced serum bilirubin, transaminases and liver fibrosis scores and increased hepatic expression of hepatocyte growth factor and STAT3alpha as compared to cirrhotic animals. Furthermore, cirrhotic animals showed testis atrophy and altered spermatogenesis, whereas testicular size and histology were normal in cirrhotic rats that received rSVIGF-I. Therefore, rSV40-mediated sustained expression of IGF-I in the liver slowed cirrhosis progression.

Reversal of fibrosis: no longer a pipe dream?

The reversal of liver fibrosis is not a new phenomenon. Treatment of the primary disease remains the most effective strategy, but new approaches to promote resolution of fibrosis are being built on the foundations that were provided by research into the basic mechanisms of fibrogenesis. A return to normal hepatic architecture from advanced fibrosis is achievable in some cases, and cirrhosis itself may be partly remediable.

Plasminogen-mediated activation and release of hepatocyte growth factor from extracellular matrix

Interventions that enhance plasminogen activation within the lung consistently limit the fibrosis that follows alveolar injury. However, this protective effect cannot be attributed solely to accelerated clearance of fibrin that forms as a provisional matrix after lung injury. To explore other mechanisms, we considered interactions between the plasminogen activation system and hepatocyte growth factor (HGF). HGF is known to have antifibrotic activity, but to do so, it must be both released from its sites of sequestration within extracellular matrix (ECM) and activated by proteolytic cleavage. A recent study using bleomycin-exposed mice showed that manipulations of the plasminogen activation system influenced the amount of free HGF within bronchoalveolar lavage fluid without affecting total lung HGF mRNA or protein. To elucidate the mechanisms, we studied the role of plasminogen activation in fibroblast-mediated HGF release and activation. We found that NIH3T3 and mouse lung fibroblasts release ECM-bound HGF in a plasminogen-dependent fashion. The plasminogen effect was lost when lung fibroblasts from urokinase-type plasminogen activator (uPA)-deficient mice were used, and was increased by fibroblasts from plasminogen activator inhibitor (PAI)-1-deficient mice. Plasminogen addition to NIH3T3 or mouse lung fibroblasts increased conversion of pro-HGF to its active form. The plasminogen effect on activation was lost when uPA-deficient fibroblasts were used and accentuated by PAI-1-deficient fibroblasts. In conjunction with the previous in vivo study, these results suggest that plasminogen activation can protect the lung against fibrosis by increasing the availability of active HGF.

Euroconference on tissue repair and ulcer/wound healing: molecular mechanisms, therapeutic targets and future directions

The meeting was part of the Euroconference series organised at the Pasteur Institute in Paris. Comprising delegates from both academia and industry, it drew on expertise from many aspects of tissue repair in a wide range of human disease. The principal component of this report concerns progress with the therapeutic application of biological agents in promoting tissue repair, as gene therapeutics, monoclonal antibodies and therapeutic proteins. In addition, the effect of pioglitazone on the rate and quality of wound healing in diabetic rats is also reported.

In Vivo Liver Electroporation: Optimization and Demonstration of Therapeutic Efficacy

Adverse effects (death and leukemogenesis) from viral vector-mediated gene therapy have renewed interest in plasmids as safer, more scalable, simple, and cost-effective vectors. Electroporation and hydrodynamic delivery are two techniques that improve the efficiency of plasmid-mediated gene transfer. The liver is a good tissue platform for targeted transfer of therapeutically relevant genes for correction of metabolic disorders, for example, hemophilia A. However, in vivo electroporation of liver has not yet been shown to achieve therapeutic efficacy of systemically active, secreted transgenic proteins. We have investigated the effect of field strength, pulse duration, pulse number, electrical waveforms, electrode contact area, plasmid administration routes, and injection technique on the efficiency of in vivo electrotransfer of naked plasmid to liver. Plasmid injection into a systemic vein was superior to intrahepatic injection. Unlike in vivo muscle electroporation, high-voltage pulses and microsecond pulses offered no advantage. Optimal electroporation conditions were 8-10 uni- or bipolar pulses of 20 msec, each at 250 V/cm. Using a nonhydrodynamic technique that greatly enhanced electrotransfer efficiency with minimal tissue injury, we demonstrate for the first time that liverdirected in vivo electroporation of factor VIII cDNA achieved significant phenotypic correction in hemophilic mice.

Targeted treatments for cirrhosis

The causes of hepatic scarring (fibrosis) are protean but, unchecked, all result in a common fate--the development of cirrhosis--with gross disruption of the normal liver architecture. Subsequent liver cell dysfunction and portal hypertension give rise to major systemic complications and premature death. Cirrhosis and its sequelae represent a huge, and global, healthcare burden. The success of liver transplantation and the development of efficacious antiviral regimens for hepatitis B and C should not be underestimated, but they also serve to highlight our current inability to manipulate the underlying fibrotic process in many patients with liver disease. Moreover, transplantation as a treatment is limited by organ availability, among other factors. The development of antifibrotic therapies is urgently needed and for this we require a mechanistic and evidence-based approach. Accumulating data from clinical and laboratory studies demonstrate that even advanced fibrosis and cirrhosis are potentially reversible. The hepatic stellate cells have been identified as the pivotal effector cells orchestrating the fibrotic process and, furthermore, reversibility appears to hinge upon their elimination. This review draws on recent scientific advances, and highlights emerging therapeutic interventions in liver fibrosis.

Treatment of experimental hepatic fibrosis by combinational delivery of urokinase-type plasminogen activator and hepatocyte growth factor genes

PURPOSE

To investigate the effect of combinational delivery of urokinase-type plasminogen activator (uPA) and hepatocyte growth factor (HGF) genes on hepatic fibrosis.

METHODS

Replication-deficient adenoviral vectors expressing either human HGF (AdHGF) or uPA (AduPA) were generated. HGF gene was transferred into primary cultured hepatocytes and uPA gene to hepatic stellate cell (HSC) to investigate the effect on the biological character of cells. Combinational adenoviruses were infused into hepatic fibrosis rats. Serum markers as well as histological and immunohistochemical examination were carried out to test the reversal of hepatic fibrosis.

RESULTS

Transfection of exogenous HGF gene induced expression of c-met/HGF receptor and stimulated hepatocyte proliferation. uPA gene delivered into HSC decreased the amount of collagen types I and III accompanied with the increased expression of matrix metalloproteinase-2. In vivo, the area of extracellular matrix in the fibrotic liver decreased to 72% in AdHGF-treated rats (P<0.01), 64% in the AduPA-treated group (P<0.01), and 51% in bi-genes transfection (P<0.01), compared with that of the controls. Moreover, immunohistochemical staining of collagen types I and III revealed that combinational genes delivery exerted more effect on reversal of hepatic fibrosis than mono-gene transfection.

CONCLUSIONS

Our study indicated that simultaneous delivery of two antifibrotic genes could confer synergistic effect on hepatic fibrosis.

Gene therapy of liver diseases

Many liver diseases lack satisfactory treatment and alternative therapeutic options are urgently needed. Gene therapy is a new mode of treatment for both inherited and acquired diseases, based on the transfer of genetic material to the tissues. Genes are incorporated into appropriate vectors in order to facilitate their entrance and function inside the target cells. Gene therapy vectors can be constructed on the basis of viral or non-viral molecular structures. Viral vectors are frequently used, due to their higher transduction efficiency. Both the type of vector and the expression cassette determine the duration, specificity and inducibility of gene expression. A considerable number of preclinical studies indicate that a great variety of liver diseases, including inherited metabolic defects, chronic viral hepatitis, liver cirrhosis and primary and metastatic liver cancer, are amenable to gene therapy. Gene transfer to the liver can also be used to convert this organ into a factory of secreted proteins needed to treat conditions that do not affect the liver itself. Clinical trials of gene therapy for the treatment of inherited diseases and liver cancer have been initiated but human gene therapy is still in its infancy. Recent progress in vector technology and imaging techniques, allowing in vivo assessment of gene expression, will facilitate the development of clinical applications of gene therapy.

Enhanced hepatocyte-selective in vivo gene expression by stabilized galactosylated liposome/plasmid DNA complex using sodium chloride for complex formation

In this study, we demonstrated that the presence of an essential amount of sodium chloride (NaCl) during the formation of cationic liposome/plasmid DNA complexes (lipoplexes) stabilizes the lipoplexes according to the surface charge regulation (SCR) theory. Fluorescence resonance energy transfer analysis revealed that cationic liposomes in an SCR lipoplex (5 and 10 mM NaCl solution in lipoplex) increased fusion. Also, aggregation of SCR lipoplexes was significantly delayed after exposure to saline (150 mM NaCl) as a model of physiological conditions. After intraportal administration, the hepatic transfection activity of galactosylated SCR lipoplexes (5 and 10 mM NaCl solution in lipoplex) was approximately 10- to 20-fold higher than that of galactosylated conventional lipoplexes in mice. The transfection activity in hepatocytes of galactosylated SCR lipoplexes was significantly higher than that of conventional lipoplexes, and preexposure to competitive asialoglycoprotein-receptor blocker significantly reduced the hepatic gene expression, suggesting that hepatocytes are responsible for high hepatic transgene expression of the galactosylated SCR lipoplexes. Pharmacokinetic studies both in situ and in vivo demonstrated a higher tissue binding affinity and a greater expanse of intrahepatic distribution by galactosylated SCR lipoplexes. Moreover, enhanced transfection activity of galactosylated SCR lipoplexes was observed in HepG2 cells, and investigation of confocal microscopic images showed that the release of plasmid DNA in the cell was markedly accelerated. These characteristics partly explain the mechanism of enhanced in vivo transfection efficacy by galactosylated SCR lipoplexes. Hence, information in this study will be valuable for the future use, design, and development of ligand-modified lipoplexes for in vivo applications.

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.

Naked DNA for Liver Gene Transfer

The majority of acquired and inherited genetic disorders, including most inborn errors of metabolism, are manifested in the liver. Therefore, it is hardly any surprise to see a large number of Medline reports describing gene therapy efforts in preclinical settings directed toward this organ (Inoue et al., 2004; Oka and Chen, 2004). Of late, non-viral vectors have garnered a lot of attention from the biomedical research community engaged in liver gene therapy (Gupta et al., 2004). However, the first initiative toward gene transfer to the liver using a non-viral approach was taken by Hickman et al. (1994), who applied the technique of naked DNA injection pioneered by Wolff (1990) for skeletal muscle. Direct injection of naked DNA resulted in low, variable and localized gene expression in the rat liver. Consequently, several developments reported in the literature since then aimed to improve hepatic gene expression by employing both surgical and nonsurgical methods. These developments include the exploitation of the unique vasculature of liver as well as the use of electric and mechanical force as an adjunct to the systemic administration of the naked plasmid gene. This chapter focuses on these developments reported from various laboratories, including ours. In addition, the underlying mechanism responsible for the dramatic increase in gene expression using these latest approaches for non-viral gene transfer to the liver is also discussed.

Effects of c-myb antisense RNA on TGF-β1 and α1-I collagen expression in cultured hepatic stellate cells

AIM: To investigate the effects of c-myb antisense RNA on cell proliferation and the expression of c-myb, TGF-β1 and α1-I collagen in cultured hepatic stellate cells (HSC) from rats.

METHODS: Recombinant retroviral vector of c-myb antisense gene (pDOR-myb) was constructed, and then transfected into retroviral package cell line PA317 by means of DOTAP. The pseudoviruses produced from the resistant PA317 cells were selected with G418 to infect HSCs isolated from rat livers. The cell proliferation was measured by 3-[4, 5-Dimethylthiazolzyl]-2, 5-diphenyl tetrazo-dium bromide (MTT) method.The expression of c-myb, α1-I collagen and TGF-β1 mRNA, and c-myb protein in HSCs was detected with semi-quantitive reverse transeription-polymerase chain reaction (RT-PCR) and Western-blot respectively.

RESULTS: HSCs from rats were isolated successfully with the viability > 98%. In the pDOR-myb infected HSCs, the c-myb protein expression, cell proliferation,and α1-I collagen and TGF-β1 mRNA expression were repressed significantly compared with their corresponding control groups (P < 0.01).

CONCLUSION: c-myb plays a key role in activation and proliferation of HSC. c-myb antisense RNA can inhibit cell proliferation, α1-I collagen and TGF-β1 mRNA expression, suggesting that inhibition of c-myb gene expression might be a potential way for the treatment of liver fibrosis.

Autocrine expression of hepatocyte growth factor and its cytoprotective effect on hepatocyte poisoning

AIM: To construct pEGFP-hepatocyte growth factor (HGF) expression vector, the to detect its expression in transfected human hepatocytes, and to investigate the influence of autocrine HGF expression on the proliferative potential and cytoprotective effects in human hepatocytes.

METHODS: Human HGF cDNA was ligated to the pEGFP vector. Recombinant plasmid was transfected into human hepatocyte line QZG with liposome. Expression of HGF protein was observed by fluorescence microscopy and immunohistochemistry. Hepatic cells were collected 24, 48, and 72 h after transfection to detect the number of [³H]-TdR uptake in DNA. DNA synthesis was observed by using PCNA stain immunohistochemistry. Acute liver cell damage was induced by carbon tetrachloride. Cytoprotective effect was observed by examining the survival rate of hepatocytes and leakage of intracellular alanine transaminase (ALT) and potassium ions.

RESULTS: HGF identification of pEGFP-HGF by enzyme digestion showed that HGF fragment was cloned into BamH I and Sal I sites of pEGFP-N3. Expression of GFP in transfected hepatocytes was observed with fluorescence microscopy. The [³H]-TdR uptake became 7 times as many as in the control group 96 h after transfection. After HGF transfection, the survival rate of hepatocytes poisoned by CCl₄ significantly increased (83% vs 61%, P < 0.05), and the leakage of intracellular alanine transaminase and potassium ions decreased (586 nkat/L vs 1089 nkat/L, P < 0.01; and 5.59 mmol/L vs 6.02 mmol/L, P < 0.01 respectively). Culture of transfected hepatic cells promoted the proliferation of other non-transfected cells.

CONCLUSION: Transfected HGF is expressed in hepatic cells and has the activity of promoting cell division and protecting hepatic cells against poisoning.

Skeletal muscle targeting in vivo electroporation-mediated HGF gene therapy of bleomycin-induced pulmonary fibrosis in mice

Lung fibrosis is a common feature of interstitial lung diseases, and apoptosis and fibrinogenesis play critical roles in its formation and progression. Hepatocyte growth factor (HGF) is one of the ideal therapeutic agents for prevention of lung fibrosis because of its antiapoptotic and fibrinolytic effects. The aim of this study is to establish nonviral HGF gene therapy of bleomycin-induced lung fibrosis avoiding the viral vector-related side effects. C57BL/6 mice were injected with 3.0 mg/kg body weight of bleomycin intratracheally. Following bleomycin injection, 50 microl of pUC-HGF (1 mg/ml) was injected into each of the quadriceps muscle. Immediately after plasmid injection, in vivo electroporation was performed with pulse generator. Skeletal muscle-targeting electroporation induced transgene expression on day 1 and persisted for 4 weeks, and human HGF was also detected in the lung. In mice transferred with HGF, pathological score (1.0+/-0.3 vs 3.2+/-0.6), TUNEL-positive cell index (4.5+/-1.1 vs 14.2+/-3.1), and hydroxyproline content (9.0+/-1.3 vs 14.4+/-5.1 micromol/g) were significantly reduced compared with the control. Furthermore, survival rate of HGF mice was significantly improved compared with the control. Our data indicate that HGF gene therapy with a single skeletal muscle-targeting electroporation has a therapeutic potential for bleomycin-induced lung fibrosis and this strategy can be applied as a practical gene therapy protocol for various organs.