Long-term expression of human alpha1-antitrypsin gene in mouse liver achieved by intravenous administration of plasmid DNA using a hydrodynamics-based procedure

Hydrodynamic Delivery: Characteristics, Applications, and Technological Advances

The principle of hydrodynamic delivery was initially used to develop a method for the delivery of plasmids into mouse hepatocytes through tail vein injection and has been expanded for use in the delivery of various biologically active materials to cells in various organs in a variety of animal species through systemic or local injection, resulting in significant advances in new applications and technological development. The development of regional hydrodynamic delivery directly supports successful gene delivery in large animals, including humans. This review summarizes the fundamentals of hydrodynamic delivery and the progress that has been made in its application. Recent progress in this field offers tantalizing prospects for the development of a new generation of technologies for broader application of hydrodynamic delivery.

Early Subcellular Hepatocellular Alterations in Mice Post Hydrodynamic Transfection: An Explorative Study

Hydrodynamic transfection (HT) or hydrodynamic tail vein injection (HTVi) is among the leading technique that is used to deliver plasmid genes mainly into the liver of live mice or rats. The DNA constructs are composed of coupled plasmids, while one contains the gene of interest that stably integrate into the hepatocyte genome with help of the other consisting sleeping beauty transposase system. The rapid injection of a large volume of DNA-solution through the tail vein induces an acute cardiac congestion that refluxed into the liver, mainly in acinus zone 3, also found through our EM study. Although, HT mediated hydrodynamic force can permeabilizes the fenestrated sinusoidal endothelium of liver, but the mechanism of plasmid incorporation into the hepatocytes remains unclear. Therefore, in the present study, we have hydrodynamically injected 2 mL volume of empty plasmid (transposon vector) or saline solution (control) into the tail vein of anesthetized C57BL/6J/129Sv mice. Liver tissue was resected at different time points from two animal group conditions, i.e., one time point per animal (1, 5, 10-20, 60 min or 24 and 48 hrs after HT) or multiple time points per animal (0, 1, 2, 5, 10, 20 min) and quickly fixed with buffered 4% osmium tetroxide. The tissues fed with only saline solution was also resected and fixed in the similar way. EM evaluation from the liver ultrathin sections reveals that swiftly after 1 min, the hepatocytes near to the central venule in the acinus zone 3 shows cytoplasmic membrane-bound vesicles. Such vesicles increased in both numbers and size to vacuoles and precisely often found in the proximity to the nucleus. Further, EM affirm these vacuoles are also optically empty and do not contain any electron dense material. Although, some of the other hepatocytes reveals sign of cell damage including swollen mitochondria, dilated endoplasmic reticulum, Golgi apparatus and disrupted plasma membrane, but most of the hepatocytes appeared normal. The ultrastructural findings in the mice injected with empty vector or saline injected control mice were similar. Therefore, we have interpreted the vacuole formation as nonspecific endocytosis without specific interactions at the plasma membrane.

In Vivo Tissue-Specific DNA Demethylation in Mouse Liver Through a Hydrodynamic Tail Vein Injection

A new technique called the dCas9-SunTag and scFv-TET1CD epigenome editing system has recently been developed to edit the DNA methylation status of specific genes. The transfection of an all-in-one vector containing this system into cells is feasible and induces the DNA demethylation of specific genes; however, due to the large size of the vector, difficulties are associated with its introduction into mice. We herein used a hydrodynamic tail vein injection (HTVi) to introduce the all-in-one vector into mice for in vivo epigenome editing. HTVi needs to be considered for inducing the targeted DNA demethylation of particular genes in the mouse liver.

Silencing IQGAP1 alleviates hepatic fibrogenesis via blocking bone marrow mesenchymal stromal cell recruitment to fibrotic liver

IQ motif-containing guanosine triphosphatase (GTPase)-activating protein 1 (IQGAP1) is a cytosolic scaffolding protein involved in cell migration. Our previous studies suggest sphingosine 1-phosphate (S1P) triggers bone marrow (BM) mesenchymal stromal cells (BMSCs) to damaged liver, thereby promoting liver fibrosis. However, the role of IQGAP1 in S1P-induced BMSC migration and liver fibrogenesis remains unclear. Chimeric mice of BM cell labeled by EGFP were used to build methionine-choline-deficient and high-fat (MCDHF)-diet-induced mouse liver fibrosis. IQGAP1 small interfering RNA (siRNA) was utilized to silence IQGAP1 in vivo. IQGAP1 expression is significantly elevated in MCDHF-diet-induced mouse fibrotic livers. Positive correlations are presented between IQGAP1 and fibrosis hallmarks expressions in human and mouse fibrotic livers. In vitro, depressing IQGAP1 expression blocks S1P-induced motility and cytoskeleton remodeling of BMSCs. S1P facilitates IQGAP1 aggregating to plasma membrane via S1P receptor 3 (S1PR₃) and Cdc42/Rac1. In addition, IQGAP1 binds to Cdc42/Rac1, regulating S1P-induced activation of Cdc42/Rac1 and mediating BMSC migration in concert. In vivo, silencing IQGAP1 reduces the recruitment of BMSCs to impaired liver and effectively alleviates liver fibrosis induced by MCDHF diet. Together, silencing IQGAP1 relieves liver fibrosis by blocking BMSC migration, providing an effective therapeutic strategy for liver fibrosis.

A Novel Gene Delivery Vector of Agonistic Anti-Radioprotective 105 Expressed on Cell Membranes Shows Adjuvant Effect for DNA Immunization Against Influenza

Radioprotective 105 (RP105) (also termed CD180) is an orphan and unconventional Toll-like receptor (TLR) that lacks an intracellular signaling domain. The agonistic anti-RP105 monoclonal antibody (mAb) can cross-link RP105 on B cells, resulting in the proliferation and activation of B cells. Anti-RP105 mAb also has a potent adjuvant effect, providing higher levels of antigen-specific antibodies compared to alum. However, adjuvanticity is required for the covalent link between anti-RP105 mAb and the antigen. This is a possible obstacle to immunization due to the link between anti-RP105 mAb and some antigens, especially multi-transmembrane proteins. We have previously succeeded in inducing rapid and potent recombinant mAbs in mice using antibody gene-based delivery. To simplify the covalent link between anti-RP105 mAb and antigens, we generated genetic constructs of recombinant anti-RP105 mAb (αRP105) bound to the transmembrane domain of the IgG-B cell receptor (TM) (αRP105-TM), which could enable the anti-RP105 mAb to link the antigen via the cell membrane. We confirmed the expression of αRP105-TM and the antigen hemagglutinin, which is a membrane protein of the influenza virus, on the same cell. We also found that αRP105-TM could activate splenic B cells, including both mature and immature cells, depending on the cell surface RP105 in vitro. To evaluate the adjuvanticity of αRP105-TM, we conducted DNA immunization in mice with the plasmids encoding αRP105-TM and hemagglutinin, followed by challenge with an infection of a lethal dose of an influenza virus. We then obtained partially but significantly hemagglutinin-specific antibodies and observed protective effects against a lethal dose of influenza virus infection. The current αRP105-TM might provide adjuvanticity for a vaccine via a simple preparation of the expression plasmids encoding αRP105-TM and of that encoding the target antigen.

Controlling Obesity and Metabolic Diseases by Hydrodynamic Delivery of a Fusion Gene of Exendin-4 and α1 Antitrypsin

Obesity and associated metabolic comorbidities represent a growing public health problem. In this study, we demonstrate the use of a newly created fusion gene of exendin-4 and α1-antitrypsin to control obesity and obesity-associated metabolic disorders including insulin resistance, fatty liver and hyperglycemia. The fusion gene encodes a protein with exendin-4 peptide placed at the N-terminus of human α-1 antitrypsin, and is named EAT. Hydrodynamic transfer of the EAT gene to mice prevents high-fat diet-induced obesity, insulin resistance and fatty liver development. In diet-induced obese mice, expression of EAT gene induces weight loss, improves glucose homeostasis, and attenuates hepatic steatosis. In ob/ob mice, EAT gene transfer suppresses body weight gain, maintains metabolic homeostasis, and completely blocks fatty liver development. Six-month overexpression of the EAT fusion gene in healthy mice does not lead to any detectable toxicity. Mechanistic study reveals that the resulting metabolic benefits are achieved by a reduced food take and down-regulation of transcription of pivotal genes responsible for lipogenesis and lipid droplet formation in the liver and chronic inflammation in visceral fat. These results validate the feasibility of gene therapy in preventing and restoring metabolic homeostasis under diverse pathologic conditions, and provide evidence in support of a new strategy to control obesity and related metabolic diseases.

In Vivo Editing of the Adult Mouse Liver Using CRISPR/Cas9 and Hydrodynamic Tail Vein Injection

CRISPR/Cas9 technology allows facile modification of the genome in virtually any desired way through the use of easily designed plasmid constructs that express a gRNA targeting a genomic site-of-interest and Cas9. Hydrodynamic tail vein injection, on the other hand, is a simple method to deliver "naked" plasmid DNA to 5-40% of the hepatocytes of the liver of adult mice. Here, we describe how these two techniques can be combined to create a workflow for fast, easy, and cost-efficient in vivo genome editing of the adult mouse liver. Using this method, large cohorts of mice with genetically modified livers can be established within 3 weeks to generate models for gene function in normal physiology and diseases of the liver.

Improved Lentiviral Gene Delivery to Mouse Liver by Hydrodynamic Vector Injection through Tail Vein

Delivery of genes to mouse liver is routinely accomplished by tail-vein injections of viral vectors or naked plasmid DNA. While viral vectors are typically injected in a low-pressure and -volume fashion, uptake of naked plasmid DNA to hepatocytes is facilitated by high pressure and volumes, also known as hydrodynamic delivery. In this study, we compare the efficacy and specificity of delivery of vesicular stomatitis virus G glycoprotein (VSV-G) pseudotyped lentiviral vectors to mouse liver by a number of injection schemes. Exploiting in vivo bioluminescence imaging as a readout after lentiviral gene transfer, we compare delivery by (1) “conventional” tail-vein injections, (2) “primed” injections, (3) “hydrodynamic” injections, or (4) direct “intrahepatic” injections into exposed livers. Reporter gene activity demonstrate potent and targeted delivery to liver by hydrodynamic injections. Enhanced efficacy is confirmed by analysis of liver sections from mice treated with GFP-encoding vectors, demonstrating 10-fold higher transduction rates and gene delivery to ∼80% of hepatocytes after hydrodynamic vector delivery. In summary, lentiviral vector transfer to mouse liver can be strongly augmented by hydrodynamic tail-vein injections, resulting in both reduced off-target delivery and transduction of the majority of hepatocytes. Our findings pave the way for more effective use of lentiviral gene delivery in the mouse.

Improved molecular platform for the gene therapy of rare diseases by liver protein secretion

Many rare monogenic diseases are treated by protein replacement therapy, in which the missing protein is repetitively administered to the patient. However, in several cases, the missing protein is required at a high and sustained level, which renders protein therapy far from being adequate. As an alternative, a gene therapy treatment ensuring a sustained effectiveness would be particularly valuable. Liver is an optimal organ for the secretion and systemic distribution of a therapeutic transgene product. Cutting edge non-viral gene therapy tools were tested in order to produce a high and sustained level of therapeutic protein secretion by the liver using the hydrodynamic delivery technique. The use of S/MAR matrix attachment region provided a slight, however not statistically significant, increase in the expression of a reporter gene in the liver. We have selected the von Willebrand Factor (vWF) gene as a particularly challenging large gene (8.4 kb) for liver delivery and expression, and also because a high vWF blood concentration is required for disease correction. By using the optimized miniplasmid pFAR free of antibiotic resistance gene together with the Sleeping Beauty transposon and the hyperactive SB100X transposase, we have obtained a sustainable level of vWFblood secretion by the liver, at 65% of physiological level. Our results point to the general use of this plasmid platform using the liver as a protein factory to treat numerous rare disorders by gene therapy.

Translational Advances of Hydrofection by Hydrodynamic Injection

Hydrodynamic gene delivery has proven to be a safe and efficient procedure for gene transfer, able to mediate, in murine model, therapeutic levels of proteins encoded by the transfected gene. In different disease models and targeting distinct organs, it has been demonstrated to revert the pathologic symptoms and signs. The therapeutic potential of hydrofection led different groups to work on the clinical translation of the procedure. In order to prevent the hemodynamic side effects derived from the rapid injection of a large volume, the conditions had to be moderated to make them compatible with its use in mid-size animal models such as rat, hamster and rabbit and large animals as dog, pig and primates. Despite the different approaches performed to adapt the conditions of gene delivery, the results obtained in any of these mid-size and large animals have been poorer than those obtained in murine model. Among these different strategies to reduce the volume employed, the most effective one has been to exclude the vasculature of the target organ and inject the solution directly. This procedure has permitted, by catheterization and surgical procedures in large animals, achieving protein expression levels in tissue close to those achieved in gold standard models. These promising results and the possibility of employing these strategies to transfer gene constructs able to edit genes, such as CRISPR, have renewed the clinical interest of this procedure of gene transfer. In order to translate the hydrodynamic gene delivery to human use, it is demanding the standardization of the procedure conditions and the molecular parameters of evaluation in order to be able to compare the results and establish a homogeneous manner of expressing the data obtained, as ‘classic’ drugs.

Neutralizing Antibodies Induced by Gene-Based Hydrodynamic Injection Have a Therapeutic Effect in Lethal Influenza Infection

The influenza virus causes annual epidemics and occasional pandemics and is thus a major public health problem. Development of vaccines and antiviral drugs is essential for controlling influenza virus infection. We previously demonstrated the use of vectored immune-prophylaxis against influenza virus infection. We generated a plasmid encoding neutralizing IgG monoclonal antibodies (mAbs) against A/PR/8/34 influenza virus (IAV) hemagglutinin (HA). We then performed electroporation of the plasmid encoding neutralizing mAbs (EP) in mice muscles and succeeded in inducing the expression of neutralizing antibodies in mouse serum. This therapy has a prophylactic effect against lethal IAV infection in mice. In this study, we established a new method of passive immunotherapy after IAV infection. We performed hydrodynamic injection of the plasmid encoding neutralizing mAbs (HD) involving rapid injection of a large volume of plasmid-DNA solution into mice via the tail vein. HD could induce neutralizing antibodies in the serum and in several mucosal tissues more rapidly than in EP. We also showed that a single HD completely protected the mice even after infection with a lethal dose of IAV. We also established other isotypes of anti-HA antibody (IgA, IgM, IgD, and IgE) and showed that like anti-HA IgG, anti-HA IgA was also effective at combating upper respiratory tract IAV infection. Passive immunotherapy with HD could thus provide a new therapeutic strategy targeting influenza virus infection.

Technical Improvement and Application of Hydrodynamic Gene Delivery in Study of Liver Diseases

Development of an safe and efficient in vivo gene delivery method is indispensable for molecular biology research and the progress in the following gene therapy. Over the past few years, hydrodynamic gene delivery (HGD) with naked DNA has drawn increasing interest in both research and potential clinic applications due to its high efficiency and low risk in triggering immune responses and carcinogenesis in comparison to viral vectors. This method, involving intravenous injection (i.v.) of massive DNA in a short duration, gives a transient but high in vivo gene expression especially in the liver of small animals. In addition to DNA, it has also been shown to deliver other substance such as RNA, proteins, synthetic small compounds and even viruses in vivo. Given its ability to robustly mimic in vivo hepatitis B virus (HBV) production in liver, HGD has become a fundamental and important technology on HBV studies in our group and many other groups. Recently, there have been interesting reports about the applications and further improvement of this technology in other liver research. Here, we review the principle, safety, current application and development of hydrodynamic delivery in liver disease studies, and discuss its future prospects, clinical potential and challenges.

Genetic Modification of the Lung Directed Toward Treatment of Human Disease

Genetic modification therapy is a promising therapeutic strategy for many diseases of the lung intractable to other treatments. Lung gene therapy has been the subject of numerous preclinical animal experiments and human clinical trials, for targets including genetic diseases such as cystic fibrosis and α1-antitrypsin deficiency, complex disorders such as asthma, allergy, and lung cancer, infections such as respiratory syncytial virus (RSV) and Pseudomonas, as well as pulmonary arterial hypertension, transplant rejection, and lung injury. A variety of viral and non-viral vectors have been employed to overcome the many physical barriers to gene transfer imposed by lung anatomy and natural defenses. Beyond the treatment of lung diseases, the lung has the potential to be used as a metabolic factory for generating proteins for delivery to the circulation for treatment of systemic diseases. Although much has been learned through a myriad of experiments about the development of genetic modification of the lung, more work is still needed to improve the delivery vehicles and to overcome challenges such as entry barriers, persistent expression, specific cell targeting, and circumventing host anti-vector responses.

In vivo direct reprogramming of liver cells to insulin producing cells by virus-free overexpression of defined factors

Direct reprogramming of autologous cells from diabetes patients to insulin producing cells is a new method for pancreatic cell replacement therapy. At present, transdifferentiation among mature cells is achieved mainly by introducing foreign genes into the starting tissue with viral vector, but there are potentical safety problems. In the present study, we delivered plasmids carrying Pdx1, Neurog3 and MafA genes (PNM) into mouse hepatocytes by hydrodynamics tail vein injection, investigated islet β cells markers in transfected cells from protein and mRNA level, and then observed the long-term control of blood glucose in diabetic mice. We found that hepatocytes could be directly reprogrammed into insulin-producing cells after PNM gene transfection by non-viral hydrodynamics injection, and fasting blood glucose was reduced to normal, and lasted until 100 days after transfection. Intraperitoneal glucose tolerance test (IPGTT) showed that glucose regulation ability was improved gradually and the serum insulin level approached to the level of normal mice with time. Insulin-positive cells were found in the liver tissue, and the expression of various islet β-cell-specific genes were detected at the mRNA level, including islet mature marker gene Ucn3. In conclusion, we provide a new approach for the treatment of diabetes by in vivo direct reprogramming of liver cells to insulin producing cells through non-viral methods.

Efficacy of hydrodynamic interleukin 10 gene transfer in human liver segments with interest in transplantation

Different diseases lead, during their advanced stages, to chronic or acute liver failure, whose unique treatment consists in organ transplantation. The success of intervention is limited by host immune response and graft rejection. The use of immunosuppressant drugs generally improve organ transplantation, but they cannot completely solve the problem. Also, their management is delicate, especially during the early stages of treatment. Thus, new tools to set an efficient modulation of immune response are required. The local expression of interleukin (IL) 10 protein in transplanted livers mediated by hydrodynamic gene transfer could improve the organ acceptance by the host because it presents the natural ability to modulate the immune response at different levels. In the organ transplantation scenario, IL10 has already demonstrated positive effects on graft tolerance. Hydrodynamic gene transfer has been proven to be safe and therapeutically efficient in animal models and could be easily moved to the clinic. In the present work, we evaluated efficacy of human IL10 gene transfer in human liver segments and the tissue natural barriers for gene entry into the cell, employing gold nanoparticles. In conclusion, the present work shows for the first time that hydrodynamic IL10 gene transfer to human liver segments ex vivo efficiently delivers a human gene into the cells. Indexes of tissue protein expression achieved could mediate local pharmacological effects with interest in controlling the immune response triggered after liver transplantation. On the other hand, the ultrastructural study suggests that the solubilized plasmid could access the hepatocyte in a passive manner mediated by the hydric flow and that an active mechanism of transportation could facilitate its entry into the nucleus. Liver Transplantation 23:50-62 2017 AASLD.

Gene Therapy for Alpha-1 Antitrypsin Deficiency Lung Disease

Alpha-1 antitrypsin (AAT) deficiency, characterized by low plasma levels of the serine protease inhibitor AAT, is associated with emphysema secondary to insufficient protection of the lung from neutrophil proteases. Although AAT augmentation therapy with purified AAT protein is efficacious, it requires weekly to monthly intravenous infusion of AAT purified from pooled human plasma, has the risk of viral contamination and allergic reactions, and is costly. As an alternative, gene therapy offers the advantage of single administration, eliminating the burden of protein infusion, and reduced risks and costs. The focus of this review is to describe the various strategies for AAT gene therapy for the pulmonary manifestations of AAT deficiency and the state of the art in bringing AAT gene therapy to the bedside.

A Novel Hydrodynamic Injection Mouse Model of HBV Genotype C for the Study of HBV Biology and the Anti-Viral Activity of Lamivudine

BACKGROUND

Absence of an immunocompetent mouse model of persistent hepatitis B virus (HBV) infection has hindered the research of HBV infection and the development of antiviral medications.

OBJECTIVES

In the present study, we aimed to develop a novel HBV genotype C mouse model by hydrodynamic injection (HI) and then used it to evaluate the antiviral activity of lamivudine.

MATERIALS AND METHODS

A quantity of 15 μg of HBV plasmid [pcDNA3.1 (+)-HBV1.3C], adeno-associated virus-HBV1.3C (pAAV-HBV1.3C) or pAAV-HBV1.2A) were injected into male C57BL/6 mice, by HI, accounting for a total of 13 mice per group. Then, lamivudine was administered to mice with sustained HBV viremia, for 4 weeks. Real-time polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry methods were used to detect HBsAg, HBeAg, HBsAb, HBcAg and HBV DNA, in serum or liver of the mice, at indicated time points.

RESULTS

In 60% of the mice injected with pcDNA3.1 (+)-HBV1.3C, HBsAg, HBeAg, HBcAg and HBV DNA persisted for > 20 weeks in liver, post-injection, with no HBsAb appearance. Meanwhile, no significant inflammation was observed in these mice. Compared with pAAV-HBV1.2A and pAAV-HBV1.3C, pcDNA3.1 (+)-HBV1.3C administration led to higher and longer HBV viremia. Furthermore, serum HBV DNA was significantly reduced by lamivudine, after 4 weeks administration, and returned to the original level, after ceasing administration for 1 week, in the mice.

CONCLUSIONS

In conclusion, our observations indicated that pcDNA3.1 (+)-HBV1.3C was superior to AAV/HBV plasmid for establishment of persistent HBV infection by HI, in vivo, and this mouse model could be useful for studies of hepatitis virology and for the development of innovatory treatments for HBV infections.

Effective Prevention of Liver Fibrosis by Liver-targeted Hydrodynamic Gene Delivery of Matrix Metalloproteinase-13 in a Rat Liver Fibrosis Model

Liver fibrosis is the final stage of liver diseases that lead to liver failure and cancer. While various diagnostic methods, including the use of serum marker, have been established, no standard therapy has been developed. The objective of this study was to assess the approach of overexpressing matrix metalloproteinase-13 gene (MMP13) in rat liver to prevent liver fibrosis progression. A rat liver fibrosis model was established by ligating the bile duct, followed by liver-targeted hydrodynamic gene delivery of a MMP13 expression vector, containing a CAG promoter-MMP13-IRES-tdTomato-polyA cassette. After 14 days, the serum level of MMP13 peaked at 71.7 pg/ml in MMP13-treated group, whereas the nontreated group only showed a level of ~5 pg/ml (P < 0.001). These levels were sustained for the next 60 days. The statistically lower level of the hyaluronic acids in treated group versus the nontreated group (P < 0.05) reveals the therapeutic effect of MMP13 overexpression. Quantitative analysis of tissue stained with sirius red showed a statistically larger volume of fibrotic tissue in the nontreated group compared to that of MMP13-treated rats (P < 0.05). These results suggest that the liver-targeted hydrodynamic delivery of MMP13 gene could be effective in the prevention of liver fibrosis.

Image-Guided Hydrodynamic Gene Delivery: Current Status and Future Directions

Hydrodynamics-based delivery has been used as an experimental tool to express transgene in small animals. This in vivo gene transfer method is useful for functional analysis of genetic elements, therapeutic effect of oligonucleotides, and cancer cells to establish the metastatic cancer animal model for experimental research. Recent progress in the development of image-guided procedure for hydrodynamics-based gene delivery in large animals directly supports the clinical applicability of this technique. This review summarizes the current status and recent progress in the development of hydrodynamics-based gene delivery and discusses the future directions for its clinical application.

Restoration of Haemoglobin Level Using Hydrodynamic Gene Therapy with Erythropoietin Does Not Alleviate the Disease Progression in an Anaemic Mouse Model for TGFβ1-Induced Chronic Kidney Disease

Erythropoietin, Epo, is a 30.4 kDa glycoprotein hormone produced primarily by the fetal liver and the adult kidney. Epo exerts its haematopoietic effects by stimulating the proliferation and differentiation of erythrocytes with subsequent improved tissue oxygenation. Epo receptors are furthermore expressed in non-haematopoietic tissue and today, Epo is recognised as a cytokine with many pleiotropic effects. We hypothesize that hydrodynamic gene therapy with Epo can restore haemoglobin levels in anaemic transgenic mice and that this will attenuate the extracellular matrix accumulation in the kidneys. The experiment is conducted by hydrodynamic gene transfer of a plasmid encoding murine Epo in a transgenic mouse model that overexpresses TGF-β1 locally in the kidneys. This model develops anaemia due to chronic kidney disease characterised by thickening of the glomerular basement membrane, deposition of mesangial matrix and mild interstitial fibrosis. A group of age matched wildtype littermates are treated accordingly. After a single hydrodynamic administration of plasmid DNA containing murine EPO gene, sustained high haemoglobin levels are observed in both transgenic and wildtype mice from 7.5 ± 0.6 mmol/L to 9.4 ± 1.2 mmol/L and 10.7 ± 0.3 mmol/L to 15.5 ± 0.5 mmol/L, respectively. We did not observe any effects in the thickness of glomerular or tubular basement membrane, on the expression of different collagen types in the kidneys or in kidney function after prolonged treatment with Epo. Thus, Epo treatment in this model of chronic kidney disease normalises haemoglobin levels but has no effect on kidney fibrosis or function.

Optimized human factor IX expression cassettes for hepatic-directed gene therapy of hemophilia B

Gene therapy provides a potential cure for hemophilia B, and significant progress has been achieved in liver-directed gene transfer mediated by adeno-associated viral vectors. Recent clinical trials involving the use of a self-complementary adeno-associated virus serotype 8-human codon-optimized factor IX (AAV8-hFIXco) vector demonstrated encouraging efficacy with hFIX expression stabilized at 1% to 6% of normal level in patients, but safety concerns related to high vector doses are still present. Thus, further improvement of AAV vectors and hFIX expression cassette may positively contribute to the ultimate success of hemophilia B gene therapy. In this study, to obtain a higher expression level of hFIX that potentiates the coagulant capacity of recipients, human FIX expression vector was optimized by upgrading the codon adaption index and adjusting the GC content, inserting a Kozak sequence (GCCACC), and introducing a gain-of-function mutation, R338L (FIX Padua). The efficiency of the published and the presently constructed cassettes was compared through in vivo screening. In addition, the regulatory elements that control the FIX gene expression in these cassettes were screened for liver-specific effectiveness. Among all the constructed cassettes, scAAV-Pre-hFIXco-SIH-R338L, which was the construct under the control of the prothrombin enhancer and prealbumin promoter, resulted in the highest level of coagulant activity, and the expression levels of two constructed cassettes (scAAV-Chi-hFIXco-SIH-R338L and scAAV-Pre-hFIXco-SIH-R338L) were also higher than that of the published cassette (scAAV-LP1-hFIXco-SJ). In summary, our strategies led to a substantial increase in hFIX expression at the protein level or a remarkably elevated coagulant activity. Thus, these reconstructs of hFIX with AAV vector may potentially contribute to the creation of an efficacious gene therapy of hemophilia B.

Hydrodynamic delivery

Hydrodynamic delivery (HD) is a broadly used procedure for DNA and RNA delivery in rodents, serving as a powerful tool for gene/protein drug discovery, gene function analysis, target validation, and identification of elements in regulating gene expression in vivo. HD involves a pressurized injection of a large volume of solution into a vasculature. New procedures are being developed to satisfy the need for a safe and efficient gene delivery in clinic. Here, we summarize the fundamentals of HD, its applications, and future perspectives for clinical use.

Minicircle: Next Generation DNA Vectors for Vaccination

The use of DNA vaccines requires pharmaceutical grade DNA that causes the immunization on the basis of a nucleic acid sequence that encodes the protein to be vaccinated against. This nucleic acid sequence can be a circular or linear plasmid, preferably a double stranded one and should not contain any other and especially not any "toxic" sequences. Sequences that are not desirable to be part of the DNA drug can be those deriving from the (typically) bacterial amplification system to produce the DNA vaccine. These could be those portions of a plasmid that are only used for controlling the bacterial replication of the plasmid or those used to select for the plasmid during cloning or even worse during production. After initial approaches to avoid the presence of these sequences in DNA vaccine plasmids with "mini-plasmids," a significant improvement in product safety was obtained by use of minicircles-circular and ccc-supercoiled expression cassettes of the DNA vaccine. Initial results proofed their extremely high expression level and recent comparison of DNA vaccines based on either plasmid or minicircle DNA show successful vaccination against HBV in mice, as shown in this overview chapter.

Gene therapy for hemophilia

Hemophilia is an X-linked inherited bleeding disorder consisting of two classifications, hemophilia A and hemophilia B, depending on the underlying mutation. Although the disease is currently treatable with intravenous delivery of replacement recombinant clotting factor, this approach represents a significant cost both monetarily and in terms of quality of life. Gene therapy is an attractive alternative approach to the treatment of hemophilia that would ideally provide life-long correction of clotting activity with a single injection. In this review, we will discuss the multitude of approaches that have been explored for the treatment of both hemophilia A and B, including both in vivo and ex vivo approaches with viral and nonviral delivery vectors.

Cell entry, efficient RNA replication, and production of infectious hepatitis C virus progeny in mouse liver-derived cells

Only humans and chimpanzees are susceptible to chronic infection by hepatitis C virus (HCV). The restricted species tropism of HCV is determined by distinct host factor requirements at different steps of the viral life cycle. In addition, effective innate immune targeting precludes efficient propagation of HCV in nonhuman cells. Species-specificity of HCV host factor usage for cell entry and virus release has been explored. However, the reason for inefficient HCV RNA replication efficiency in mouse liver cells remains elusive. To address this, we generated novel mouse liver-derived cell lines with specific lesions in mitochondrial antiviral signaling protein (MAVS), interferon regulatory factor 3 (IRF3), or Interferon-α/β receptor (IFNAR) by in vivo immortalization. Blunted innate immune responses in these cells modestly increased HCV RNA replication. However, ectopic expression of liver-specific human microRNA 122 (miR-122) further boosted RNA replication in all knockout cell lines. Remarkably, MAVS(-/-) miR-122 cells sustained vigorous HCV RNA replication, attaining levels comparable to the highly permissive human hepatoma cell line Huh-7.5. RNA replication was dependent on mouse cyclophilin and phosphatidylinositol-4 kinase III alpha (PI4KIIIα) and was also observed after transfection of full-length viral RNA. Additionally, ectopic expression of either human or mouse apolipoprotein E (ApoE) was sufficient to permit release of infectious particles. Finally, expression of human entry cofactors rendered these cells permissive to HCV infection, thus confirming that all steps of the HCV replication cycle can be reconstituted in mouse liver-derived cells.

CONCLUSION

Blunted innate immunity, abundant miR-122, and HCV entry factor expression permits propagation of HCV in mouse liver-derived cell lines.

Parameters Affecting Image-guided, Hydrodynamic Gene Delivery to Swine Liver

Development of a safe and effective method for gene delivery to hepatocytes is a critical step toward gene therapy for liver diseases. Here, we assessed the parameters for gene delivery to the livers of large animals (pigs, 40-65 kg) using an image-guided hydrodynamics-based procedure that involves image-guided catheter insertion into the lobular hepatic vein and hydrodynamic injection of reporter plasmids using a computer-controlled injector. We demonstrated that injection parameters (relative position of the catheter in the hepatic vasculature, intravascular pressure upon injection, and injection volume) are directly related to the safety and efficiency of the procedure. By optimizing these parameters, we explored for the first time, the advantage of the procedure for sequential injections to multiple lobes in human-sized pigs. The optimized procedure resulted in sustained expression of the human α-1 antitrypsin gene in livers for more than 2 months after gene delivery. In addition, repeated hydrodynamic gene delivery was safely conducted and no adverse events were seen in the entire period of the study. Our results support the clinical applicability of the image-guided hydrodynamic gene delivery method for the treatment of liver diseases.Molecular Therapy-Nucleic Acids (2013) 2, e128; doi:10.1038/mtna.2013.52; published online 15 October 2013.

Novel electric power-driven hydrodynamic injection system for gene delivery: safety and efficacy of human factor IX delivery in rats

The development of a safe and reproducible gene delivery system is an essential step toward the clinical application of the hydrodynamic gene delivery (HGD) method. For this purpose, we have developed a novel electric power-driven injection system called the HydroJector-EM, which can replicate various time-pressure curves preloaded into the computer program before injection. The assessment of the reproducibility and safety of gene delivery system in vitro and in vivo demonstrated the precise replication of intravascular time-pressure curves and the reproducibility of gene delivery efficiency. The highest level of luciferase expression (272 pg luciferase per mg of proteins) was achieved safely using the time-pressure curve, which reaches 30 mm Hg in 10 s among various curves tested. Using this curve, the sustained expression of a therapeutic level of human factor IX protein (>500 ng ml(-1)) was maintained for 2 months after the HGD of the pBS-HCRHP-FIXIA plasmid. Other than a transient increase in liver enzymes that recovered in a few days, no adverse events were seen in rats. These results confirm the effectiveness of the HydroJector-EM for reproducible gene delivery and demonstrate that long-term therapeutic gene expression can be achieved by automatic computer-controlled hydrodynamic injection that can be performed by anyone.

Induction of interleukin 2 expression in the liver for the treatment of H22 hepatoma in mice

BACKGROUND AND AIMS

We designed this study to evaluate the ability of a plasmid carrying an RU486 regulatory system to induce expression of interleukin-2 (IL-2) gene and to examine the antitumour efficacy of the induced IL-2 gene.

METHODS

The plasmid pRS-mIL-2,which contains an RU486 inducible system and IL-2 gene was injected into mice. Sera and tissues from liver, spleen, lungs and kidneys were taken to test the properties of the plasmid. To examine the antitumour efficacy of pRS-mIL-2, tumours were established in the liver by direct inoculation of H22 hepatoma cells.

RESULTS

The IL-2 levels in serum correlated with the dose of plasmid and RU486. High and sustained IL-2 levels could be achieved by administration of RU486 every day. The mRNA of transgene IL-2 was found only in the liver. Treatment of mice with pRS-mIL-2 plus RU486 resulted in the significant reduction in tumour volume compared with control groups.

CONCLUSIONS

Tight temporal and spatial control of transgene IL-2 expression can be achieved by a plasmid containing an RU486 inducible system driven by liver specific promoter. pRS-mIL-2 exhibited strong antitumour efficacy following consecutive induction with RU486.

Cholangiocarcinomas can originate from hepatocytes in mice

Intrahepatic cholangiocarcinomas (ICCs) are primary liver tumors with a poor prognosis. The development of effective therapies has been hampered by a limited understanding of the biology of ICCs. Although ICCs exhibit heterogeneity in location, histology, and marker expression, they are currently thought to derive invariably from the cells lining the bile ducts, biliary epithelial cells (BECs), or liver progenitor cells (LPCs). Despite lack of experimental evidence establishing BECs or LPCs as the origin of ICCs, other liver cell types have not been considered. Here we show that ICCs can originate from fully differentiated hepatocytes. Using a mouse model of hepatocyte fate tracing, we found that activated NOTCH and AKT signaling cooperate to convert normal hepatocytes into biliary cells that act as precursors of rapidly progressing, lethal ICCs. Our findings suggest a previously overlooked mechanism of human ICC formation that may be targetable for anti-ICC therapy.

α-1-antitrypsin gene delivery reduces inflammation, increases T-regulatory cell population size and prevents islet allograft rejection

Antiinflammatory clinical-grade, plasma-derived human α-1 antitrypsin (hAAT) protects islets from allorejection as well as from autoimmune destruction. hAAT also interferes with disease progression in experimental autoimmune encephalomyelitis (EAE) and in collagen-induced arthritis (CIA) mouse models. hAAT increases IL-1 receptor antagonist expression in human mononuclear cells and T-regulatory (Treg) cell population size in animal models. Clinical-grade hAAT contains plasma impurities, multiple hAAT isoforms and various states of inactive hAAT. We thus wished to establish islet-protective activities and effect on Treg cells of plasmid-derived circulating hAAT in whole animals. Islet function was assessed in mice that received allogeneic islet transplants after mice were given hydrodynamic tail-vein injection with pEF-hAAT, a previously described Epstein-Barr virus (EBV) plasmid construct containing the EBV nuclear antigen 1 (EBNA1) and the family of repeat EBNA1 binding site components (designated "EF") alongside the hAAT gene. Sera collected from hAAT-expressing mice were added to lipopolysaccharide (LPS)-stimulated macrophages to assess macrophage responsiveness. Also, maturation of peritoneal cells from hAAT-expressing mice was evaluated. hAAT-expressing mice accepted islet allografts (n = 11), whereas phosphate-buffered saline-injected animals (n = 11), as well as mice treated with truncated-hAAT-plasmid (n = 6) and untreated animals (n = 20) rapidly rejected islet allografts. In hAAT-expressing animals, local Treg cells were abundant at graft sites, and the IL-1 receptor antagonist was elevated in grafts and circulation. Sera from hAAT-expressing mice, but not control mice, inhibited macrophage responses. Finally, peritoneal cells from hAAT-expressing mice exhibited a semimature phenotype. We conclude that plasmid-derived circulating hAAT protects islet allografts from acute rejection, and human plasma impurities are unrelated to islet protection. Future studies may use this in vivo approach to examine the structure-function characteristics of the protective activities of AAT by manipulation of the hAAT plasmid.

Analysis of metabolic and gene expression changes after hydrodynamic DNA injection into mouse liver

The hydrodynamic injection in mice tail vein of a plasmid (40 µg DNA) bearing the human α1-antitrypsin gene mediates: a) good liver gene transfer resulting in therapeutic plasma levels of human protein (1 mg/ml, approximately) from days 1-10 after injection; b) low liver injury as demonstrated by a poor and transient increase of aspartate aminotransferase (AST) and alanine transaminase (ALT) in mouse plasma; 3) limited expression and metabolic changes in host liver genes and metabolites as evaluated on days 2 and 10 after injection. Groups of three mice were uninjected (control) or hydrodynamically injected with saline or plasmid DNA and then sacrificed on days 2 and 10 after injection. The results of principal component analysis (PCA) show, both in expression microarray and metabolomic analysis, that changes between control and hydrodynamically injected groups are not dramatic and tend to normalize after 10 d. The differences are even smaller between DNA and saline hydrodynamically injected mice. Hydrodynamic injection induces a complex but limited gene expression and metabolic change which includes variations in molecules related to energy metabolism and stress response. The results contribute to support that hydrodynamic method is a safe procedure of liver gene transfer but the long-term effect of hydrodynamic gene transfer procedure, remains to be studied.

AAV plasmid DNA simplifies liver-directed in vivo gene therapy: comparison of expression levels after plasmid DNA-, adeno-associated virus- and adenovirus-mediated liver transfection

BACKGROUND

Successful liver gene therapy depends on efficient gene transfer techniques and long-lasting gene expression after successful transfer. Over the last decades, important progress has been made with the introduction of viral vectors using animal models, although their use is hampered by a complex and costly preparation compared to the simple and cost-effective preparation of plasmid DNA. These problems become even more critical when considering the application of viral vectors in human gene therapy and gene therapy trials. In a previous study, we were able to show that the hydrodynamics-based gene transfer of plasmid-DNA, containing the adeno-associated-virus specific inverted terminal repeats (AAV-ITR), prolongs gene expression in the liver, although it remained unclear whether plasmid gene transfer could achieve similar expression levels compared to viral-vector gene transfer.

METHODS

Rat livers were transfected in-vivo with AAV-ITR-containing plasmid-DNA using a modified hydrodynamics-based procedure. Expression levels were monitored thereafter and compared with expression levels after viral-vector gene transfer.

RESULTS

A high and stable long-term expression was achieved after in vivo transfection of rat livers with AAV-ITR-containing plasmids. The expression course resembled that after AAV-mediated gene transfer, and the expression was at least as high, and lasted as long, compared to recombinant AAV-mediated gene transfer.

CONCLUSIONS

We consider AAV-ITR-containing plasmids as a simple and cost-effective alternative to recombinant viral vectors, especially for liver-directed gene therapy in rodents. With ongoing progress in gene transfer methods for naked DNA, these plasmids may also become a successful alternative to recombinant viral vectors in human gene therapy.

High capacity extrachromosomal gene expression vectors

Extrachromosomal gene expression vectors that contain native genomic gene expression elements have numerous advantages over traditional integrating mini-gene vectors. In this protocol chapter we describe our work using episomal vectors where expression of a cDNA is controlled by a 10 kB piece of genomic DNA encompassing the promoter of the low density lipoprotein receptor. We explain methods to sub-clone large genomic inserts into gene expression vectors. We also illustrate various methods employed to ascertain whether expression from these vectors is robust and physiologically relevant by investigating their sensitivity to changes in cellular milieu. Delivery of gene expression vectors in vivo is also described using hydrodynamic tail vein injection, a high pressure, high volume tail vein injection used for liver-directed gene transfer.

Hydrodynamic gene delivery and its applications in pharmaceutical research

Hydrodynamic delivery has emerged as the simplest and most effective method for intracellular delivery of membrane-impermeable substances in rodents. The system employs a physical force generated by a rapid injection of large volume of solution into a blood vessel to enhance the permeability of endothelium and the plasma membrane of the parenchyma cells to allow delivery of substance into cells. The procedure was initially established for gene delivery in mice, and its applications have been extended to the delivery of proteins, oligo nucleotides, genomic DNA and RNA sequences, and small molecules. The focus of this review is on applications of hydrodynamic delivery in pharmaceutical research. Examples are provided to highlight the use of hydrodynamic delivery for study of transcriptional regulation of CYP enzymes, for establishment of animal model for viral infections, and for gene drug discovery and gene function analysis.

Intracellular gene transfer in rats by tail vein injection of plasmid DNA

In this study, we examined the effect of various factors on gene delivery efficiency of tail vein injection of plasmid DNA into rats. We measured the level of reporter gene expression in the internal organs including the lung, heart, spleen, kidney, and liver as function of injection volume, injection time, and DNA dose. Persistency of reporter gene expression in transfected animals was also examined. We demonstrated that plasmid delivery to rats by the tail vein is effective as long as the volume of injected DNA solution is adjusted to 7-8% of body weight with an injection time of less than 10 s. With the exception of a short-term increase in serum concentration of alanine aminotransferase and transient irregularity in cardiac function during and soon after the injection, the procedure is well tolerated. Lac Z staining of the liver from transfected animals showed approximately 5-10% positive cells. Persistency test for transgene expression in animals using plasmid carrying cDNA of human alpha 1 antitrypsin gene driven by chicken beta actin gene promoter with CMV enhancers showed peak level of transgene product 1 day after the injection followed by a gradual decline with time. Peak level was regained by a second injection performed on day 38 after the first injection. These results show that tail vein injection is an effective means for introducing plasmid DNA into liver cells in rats. We believe that this procedure will be extremely useful for gene function studies in the context of whole animal in rats.

pFARs, plasmids free of antibiotic resistance markers, display high-level transgene expression in muscle, skin and tumour cells

BACKGROUND

Nonviral gene therapy requires a high yield and a low cost production of eukaryotic expression vectors that meet defined criteria such as biosafety and quality of pharmaceutical grade. To fulfil these objectives, we designed a novel antibiotic-free selection system.

METHODS

The proposed strategy relies on the suppression of a chromosomal amber mutation by a plasmid-borne function. We first introduced a nonsense mutation into the essential Escherichia coli thyA gene, resulting in thymidine auxotrophy. The bacterial strain was optimized for the production of small and novel plasmids free of antibiotic resistance markers (pFARs) and encoding an amber suppressor t-RNA. Finally, the potentiality of pFARs as eukaryotic expression vectors was assessed by monitoring luciferase activities after electrotransfer of LUC-encoding plasmids into various tissues.

RESULTS

The introduction of pFARs into the optimized bacterial strain restored normal growth to the auxotrophic mutant and allowed an efficient production of monomeric supercoiled plasmids. The electrotransfer of LUC-encoding pFAR into muscle led to high luciferase activities, demonstrating an efficient gene delivery. In transplanted tumours, transgene expression levels were superior after electrotransfer of the pFAR derivative compared to a plasmid carrying a kanamycin resistance gene. Finally, in skin, whereas luciferase activities decreased within 3 weeks after intradermal electrotransfer of a conventional expression vector, sustained luciferase expression was observed with the pFAR plasmid.

CONCLUSIONS

Thus, we have designed a novel strategy for the efficient production of biosafe plasmids and demonstrated their potentiality for nonviral gene delivery and high-level transgene expression in several tissues.

Evaluation of hepatitis B virus promoters for sustained transgene expression in mice by bioluminescence imaging

To find new liver-specific expression cassettes for long-term expression of therapeutic genes in the context of pDNA, the function and specificity of hepatitis B virus (HBV)' two hepatic enhancers (EnI and EnII), combined with HBV core and X promoters in cultured cells were evaluated. By bioluminescence imaging and hydrodynamic gene transfer technology, the persistence of transgene expression containing these regulatory sequences in the liver of mice was assessed. Our data indicated that both HBV enhancers were able to stimulate HBV core and X promoter activity in cultured cells of hepatic origin. In vivo, HBV core promoter linked to EnI and EnII (EII-EI-Pc) and X promoter linked to EnI and EnII (EI-EII-Px) could direct a constant and high-level gene expression.

Long-term physiologically regulated expression of the low-density lipoprotein receptor in vivo using genomic DNA mini-gene constructs

Familial hypercholesterolemia (FH) is a condition caused by mutations in the low-density lipoprotein receptor (LDLR) gene. Expression of LDLR is highly regulated and excess receptor expression is cytotoxic. To incorporate essential gene regulation into a gene therapy vector for FH, we generated vectors in which the expression of therapeutic human LDLR gene, or luciferase reporter gene, is driven by 10 kb of human LDLR genomic DNA encompassing the promoter region including elements essential for physiologically regulated expression. Using luciferase expression and specific LDL binding and internalization assays, we have shown in vitro that the genomic promoter element confers long-term, physiologically regulated gene expression and complementation of receptor deficiency in culture for 240 cell-generations. This was demonstrated in the presence of sterols or statins, modifiers of LDLR promoter activity. In vivo, we demonstrate efficient liver-specific delivery and expression of luciferase following hydrodynamic tail-vein injection and confirm that expression from the LDLR promoter element is sensitive to statin administration. We also demonstrate long-term LDLR expression from the 10-kb promoter element up to 9 months following delivery. The vector system that we describe provides the efficient delivery, long-term expression, and physiological regulation required for a successful gene therapy intervention for FH.

Nonviral gene delivery: principle, limitations, and recent progress

Gene therapy is becoming a promising therapeutic modality for the treatment of genetic and acquired disorders. Nonviral approaches as alternative gene transfer vehicles to the popular viral vectors have received significant attention because of their favorable properties, including lack of immunogenicity, low toxicity, and potential for tissue specificity. Such approaches have been tested in preclinical studies and human clinical trials over the last decade. Although therapeutic benefit has been demonstrated in animal models, gene delivery efficiency of the nonviral approaches remains to be a key obstacle for clinical applications. This review focuses on existing and emerging concepts of chemical and physical methods for delivery of therapeutic nucleic acid molecules in vivo. The emphasis is placed on discussion about problems associated with current nonviral methods and recent efforts toward refinement of nonviral approaches.

Nonviral jet-injection technology for intratumoral in vivo gene transfer of naked DNA

The main challenges for application of gene therapy to patients are poor selectivity in vector targeting, insufficient gene transfer, and great difficulties in systemic treatment in association with safety concerns for particular vector systems. For success in gene therapy, safe, applicable, and efficient transfer technologies are required. Because of the complex nature of targeted vector delivery to the tumor, our strategy for gene therapy is focused on the development of local nonviral gene transfer. This approach of local interference with tumor growth and progression could contribute to better control of the disease. Transfer of naked DNA is an important alternative to liposomal or viral systems. Different physical procedures are used for improved delivery of naked DNA into the target cells or tissues in vitro and in vivo. Among the various nonviral gene delivery technologies, jet-injection is gaining increased attractiveness, because this technique allows gene transfer into different tissues with deep penetration of naked DNA by circumventing the disadvantages associated with, e.g., viral vectors. The jet-injection technology is based on jets of high velocity for penetration of the skin and underlaying tissues, associated with efficient transfection of the affected area. The jet-injection technology has been successfully applied for in vivo gene transfer in different tumor models. More importantly, the efficacy and safety of jet-injection gene transfer have recently been investigated in a phase I clinical trial.

Lentiviral gene transfer to reduce atherosclerosis progression by long-term CC-chemokine inhibition

CC-chemokines are important mediators in the pathogenesis of atherosclerosis. Atherosclerosis progression is reduced by high-level, short-term inhibition of CC-chemokine activity, for example by adenoviral gene transfer. However, atherosclerosis is a chronic condition where short-term effects, while demonstrating proof-of-principle, are unlikely to provide maximum therapeutic benefit. Accordingly, we generated a recombinant lentivirus, lenti35K, encoding the broad-spectrum CC chemokine inhibitor, 35K, derived from the vaccinia virus. To investigate the effects of prolonged broad-spectrum chemokine inhibition on atherosclerosis, lenti35K, or lentiGFP or PBS were delivered to 6-week-old ApoE knockout (ApoE-KO) mice by hydrodynamic injection. Sustained lentiviral transduction and transgene expression were demonstrated by 35K mRNA and viral DNA in liver tissue, and recombinant 35K protein circulating in the plasma, 3 months after gene transfer. Plasma from lenti35K animals had reduced chemokine activity compared with plasma from lentiGFP or PBS-treated animals. Histologic analysis of aortic sinus sections revealed that atherosclerotic plaque area in lenti35K mice was significantly reduced compared with both lentiGFP and PBS controls. Furthermore, plaque macrophage content was substantially reduced in lenti35K mice. Lentiviral 35K gene transfer is a promising experimental strategy to reduce atherosclerosis progression, and demonstrates the potential of long-term CC-chemokine inhibition as a potential therapeutic target in atherosclerosis.

Sustained liver-specific transgene expression from the albumin promoter in mice following hydrodynamic plasmid DNA delivery

BACKGROUND

To properly study gene expression in vivo, often long-term expression is desired. Previous studies using plasmid DNA (pDNA) vectors have typically resulted in short-term expression. Here, we evaluated combinations of the albumin promoter with different enhancers and untranslated regions for liver-specific expression in mice.

METHODS

A series of pDNA secreted alkaline phosphatase (SEAP) reporter gene expression vectors was constructed using the albumin promoter and various other expression cassette elements. Each was evaluated for level and duration of SEAP expression in mice following hydrodynamic tail vein delivery.

RESULTS

Sustained liver expression was obtained from vectors combining the albumin promoter with an albumin 3' untranslated region (3'UTR). The level of expression was increased by inclusion of enhancers and a 5' intron. The optimal expression vector consisted of the albumin promoter combined with an alpha-fetoprotein MERII enhancer, 5' intron from the factor IX gene, and the 3'UTR from the albumin gene including intron 14. With this vector, SEAP reporter gene expression levels remained high for 1 year, at levels comparable to those obtained from the cytomegalovirus (CMV) promoter on day 1. Expression of human apolipoprotein E3 (hApoE) in ApoE knockout mice provided a dose-dependent correction of their hypercholesterolemia.

CONCLUSIONS

Liver-specific sustained transgene expression can be obtained at very high levels from optimized pDNA vectors, without the use of integration systems. Such vectors will further facilitate biological studies of genes in vivo and may find application in gene therapy.

Computer-assisted hydrodynamic gene delivery

The recently developed hydrodynamic delivery method makes it possible to deliver DNA and RNA into parenchyma cells by intravascular injection of nucleic acid-containing solution. While this procedure is effective in rodents, it is difficult to perform in large animals, because manual control while delivering the injection cannot be sufficiently reliable for achieving a just-right hydrodynamic pressure in targeted tissue. In order to overcome this problem, we have developed a computer-controlled injection device that uses real-time intravascular pressure as a regulator. Using the new injection device, and mouse liver as the model organ, we demonstrated continuous injection at a single pressure and different pressures, and also serial (repeated) injections at intervals of 250 ms, by programming the computer according to the need. When assessed by reporter plasmids, the computer-controlled injection device exhibits gene delivery efficiency similar to that of conventional hydrodynamic injection. The device is also effective in gene delivery to kidney and muscle cells in rats, with plasmids or adenoviral vectors as gene carriers. Successful gene delivery to liver and kidney was also demonstrated in pigs, with the computer-controlled injection being combined with image-guided catheterization. These results represent a significant advance in in vivo gene delivery research, with potential for use in gene therapy in humans.