Designing gene delivery vectors for cardiovascular gene therapy

Ultrasound-mediated HGF Gene Microbubbles Mitigate Hyperkinetic Pulmonary Arterial Hypertension in Rabbits

AIM

Hyperkinetic pulmonary arterial hypertension (PAH) is a complication of congenital heart disease. Gene therapy is a new experimental treatment for PAH, and ultrasound-mediated gene-carrying microbubble targeted delivery is a promising development for gene transfer.

METHODS

This study successfully established a hyperkinetic PAH rabbit model by a common carotid artery and jugular vein shunt using the cuff style method. Liposome microbubbles carrying the hepatocyte growth factor (HGF) gene were successfully constructed. An in vitro experiment evaluated the appropriate intensity of ultrasonic radiation by Western blots and 3H-TdR incorporation assays. In an in vivo experiment, after transfection of ultrasound-mediated HGF gene microbubbles, catheterisation was applied to collect haemodynamic data. Hypertrophy of the right ventricle was evaluated by measuring the right ventricle hypertrophy index. Western blot and immunohistochemistry analyses were used to detect the expression of human (h)HGF and angiogenic effects, respectively.

RESULTS

The most appropriate ultrasonic radiation intensity was 1.0 W/cm2 for 5 minutes. Two weeks after transfection, both systolic pulmonary arterial pressure and mean pulmonary arterial pressure were attenuated. Hypertrophy of the right ventricle was reversed. hHGF was transplanted into the rabbits, resulting in a high expression of hHGF protein and an increase in the number of small pulmonary arteries. Ultrasound-mediated HGF gene microbubble therapy was more effective at attenuating PAH and increasing the density of small pulmonary arteries than single HGF plasmid transfection.

CONCLUSIONS

Ultrasound-mediated HGF gene microbubbles significantly improved the target of gene therapy in a rabbit PAH model and enhanced the tropism and transfection rates. Thus, the technique can effectively promote small pulmonary angiogenesis and play a role in the treatment of PAH without adverse reactions.

Theranostic Applications of Nanomaterials in the Field of Cardiovascular Diseases

A large percentage of people are being exposed to mortality due to cardiovascular diseases. Convention approaches have not provided satisfactory outcomes in the management of these diseases. To overcome the limitations of conventional approaches, nanomaterials like nanoparticles, nanotubes, micelles, lipid based nanocarriers, dendrimers, carbon based nano-formulations represent the new aspect of diagnosis and treatment of cardiovascular diseases. The unique inherent properties of the nanomaterials are the major reasons for their rapidly growing demand in the field of medicine. Profound knowledge in the field of nanotechnology and biomedicine is needed for the notable translation of nanomaterials into theranostic cardiovascular applications. In this review, the authors have summarized different nanomaterials which are being extensively used to diagnose and treat the diseases such as coronary heart disease, myocardial infarction, atherosclerosis, stroke and thrombosis.

Delivery of viral vectors for gene therapy in intimal hyperplasia and restenosis in atherosclerotic swine

Cardiovascular diseases including atherosclerosis are a major financial and health burden globally. Inflammation associated with atherosclerosis results in the development of plaques that can rupture causing thrombosis, stroke, or death. The most widely used treatment for the removal of atherosclerotic plaques is percutaneous transluminal coronary angioplasty (PTCA) with or without stenting. Although this is a safer and minimally invasive method, restenosis and intimal hyperplasia after interventional procedure remains a major hurdle and more refined approaches are needed. Studies in large animal models such as pigs have facilitated a greater understanding of the underlying mechanisms of the disease and provided novel targets for therapeutic intervention. In pre-clinical studies, viral vector gene therapy has emerged as a promising option for the reduction and/or prevention of restenosis and intimal hyperplasia. Although studies in animal models have generated promising results, clinical trials have yet to prove the clinical efficacy of gene therapy in coronary artery diseases. In this review, we examined and critically reviewed the most recent advances in viral vector gene therapy obtained from studies using porcine model of atherosclerosis.

Temporal endogenous gene expression profiles in response to lipid-mediated transfection

BACKGROUND

Design of efficient nonviral gene delivery systems is limited as a result of the rudimentary understanding of the specific molecules and processes that facilitate DNA transfer.

METHODS

Lipoplexes formed with Lipofectamine 2000 (LF2000) and plasmid-encoding green fluorescent protein (GFP) were delivered to the HEK 293T cell line. After treating cells with lipoplexes, HG-U133 Affymetrix microarrays were used to identify endogenous genes differentially expressed between treated and untreated cells (2 h exposure) or between flow-separated transfected cells (GFP+) and treated, untransfected cells (GFP-) at 8, 16 and 24 h after lipoplex treatment. Cell priming studies were conducted using pharmacologic agents to alter endogenous levels of the identified differentially expressed genes to determine effect on transfection levels.

RESULTS

Relative to untreated cells 2 h after lipoplex treatment, only downregulated genes were identified ≥ 30-fold: ALMS1, ITGB1, FCGR3A, DOCK10 and ZDDHC13. Subsequently, relative to GFP- cells, the GFP+ cell population showed at least a five-fold upregulation of RAP1A and PACSIN3 (8 h) or HSPA6 and RAP1A (16 and 24 h). Pharmacologic studies altering endogenous levels for ALMS1, FCGR3A, and DOCK10 (involved in filopodia protrusions), ITGB1 (integrin signaling), ZDDHC13 (membrane trafficking) and PACSIN3 (proteolytic shedding of membrane receptors) were able to increase or decrease transgene production.

CONCLUSIONS

RAP1A, PACSIN3 and HSPA6 may help lipoplex-treated cells overcome a transcriptional shutdown due to treatment with lipoplexes and provide new targets for investigating molecular mechanisms of transfection or for enhancing transfection through cell priming or engineering of the nonviral gene delivery system.

Temporal endogenous gene expression profiles in response to polymer-mediated transfection and profile comparison to lipid-mediated transfection

BACKGROUND

Design of efficient nonviral gene delivery systems is limited by the rudimentary understanding of specific molecules that facilitate transfection.

METHODS

Polyplexes using 25-kDa polyethylenimine (PEI) and plasmid-encoding green fluorescent protein (GFP) were delivered to HEK 293T cells. After treating cells with polyplexes, microarrays were used to identify endogenous genes differentially expressed between treated and untreated cells (2 h of exposure) or between flow-separated transfected cells (GFP+) and treated, untransfected cells (GFP-) at 8, 16 and 24 h after lipoplex treatment. Cell priming studies were conducted using pharmacologic agents to alter endogenous levels of the identified differentially expressed genes to determine effect on transfection levels. Differentially expressed genes in polyplex-mediated transfection were compared with those differentially expressed in lipoplex transfection to identify DNA carrier-dependent molecular factors.

RESULTS

Differentially expressed genes were RGS1, ARHGAP24, PDZD2, SNX24, GSN and IGF2BP1 after 2 h; RAP1A and ACTA1 after 8 h; RAP1A, WDR78 and ACTA1 after 16 h; and RAP1A, SCG5, ATF3, IREB2 and ACTA1 after 24 h. Pharmacologic studies altering endogenous levels for ARHGAP24, GSN, IGF2BP1, PDZD2 and RGS1 were able to increase or decrease transgene production. Comparing differentially expressed genes for polyplexes and lipoplexes, no common genes were identified at the 2-h time point, whereas, after the 8-h time point, RAP1A, ATF3 and HSPA6 were similarly expressed. SCG5 and PGAP1 were only upregulated in polyplex-transfected cells.

CONCLUSIONS

The identified genes and pharmacologic agents provide targets for improving transfection systems, although polyplex or lipoplex dependencies must be considered.

Integrating mitosis, toxicity, and transgene expression in a telecommunications packet-switched network model of lipoplex-mediated gene delivery

Gene delivery systems transport exogenous genetic information to cells or biological systems with the potential to directly alter endogenous gene expression and behavior with applications in functional genomics, tissue engineering, medical devices, and gene therapy. Nonviral systems offer advantages over viral systems because of their low immunogenicity, inexpensive synthesis, and easy modification but suffer from lower transfection levels. The representation of gene transfer using models offers perspective and interpretation of complex cellular mechanisms,including nonviral gene delivery where exact mechanisms are unknown. Here, we introduce a novel telecommunications model of the nonviral gene delivery process in which the delivery of the gene to a cell is synonymous with delivery of a packet of information to a destination computer within a packet-switched computer network. Such a model uses nodes and layers to simplify the complexity of modeling the transfection process and to overcome several challenges of existing models. These challenges include a limited scope and limited time frame, which often does not incorporate biological effects known to affect transfection. The telecommunication model was constructed in MATLAB to model lipoplex delivery of the gene encoding the green fluorescent protein to HeLa cells. Mitosis and toxicity events were included in the model resulting in simulation outputs of nuclear internalization and transfection efficiency that correlated with experimental data. A priori predictions based on model sensitivity analysis suggest that increasing endosomal escape and decreasing lysosomal degradation, protein degradation, and GFP-induced toxicity can improve transfection efficiency by three-fold. Application of the telecommunications model to nonviral gene delivery offers insight into the development of new gene delivery systems with therapeutically relevant transfection levels.

Network analysis of endogenous gene expression profiles after polyethyleneimine-mediated DNA delivery

BACKGROUND

DNA delivery systems, which transport exogenous DNA to cells, have applications that include gene therapy, tissue engineering and medical devices. Although the cationic nonviral DNA carrier polyethyleneimine (PEI) has been widely studied, the molecular factors and pathways underlying PEI-mediated DNA transfer remain largely unknown, preventing the design of more efficient delivery systems.

METHODS

HEK 293 T cells were treated with polyplexes formed with PEI and pEGFPLuc encoding for green fluorescent protein (GFP). Transfected cells expressing GFP were flow-separated from treated, untransfected cells. Gene expression profiles were obtained using Affymetrix HG-U133 2.0 microarrays and differentially expressed genes were identified using R/Bioconductor. Gene network analysis using EGAN (exploratory gene association network) bioinformatics tools was then used to find interaction among genes and enriched gene ontology (GO) terms related to transfection. Genes identified by this method were perturbed using pharmacologic activators or inhibitors to assess their effect on DNA transfer.

RESULTS

Microarray analysis comparing transfected cells to untransfected cells revealed 215 genes to be differentially expressed, with the majority enriched to GO processes including metabolism, response to stimulus, cell cycle, biological regulation and cellular component organization or biogenesis pathways. Gene network analysis revealed a coordinated induction of RAP1A, SCG5, PGAP1, ATF3 and NEB genes implicated in cell stress, cell cycle and cytoskeletal processes. Altering pathways with pharmacologic agents confirmed the potential role of RAP1A, SCG5 and ATF3 in transfection.

CONCLUSIONS

Microarray and gene network analyses of the sorted, transfected cell population can identify potential mediators of transfection, providing a basis for the design of improved delivery systems.

Gene therapy in corneal transplantation

Corneal transplantation is the most commonly performed organ transplantation. Immune privilege of the cornea is widely recognized, partly because of the relatively favorable outcome of corneal grafts. The first-time recipient of corneal allografts in an avascular, low-risk setting can expect a 90% success rate without systemic immunosuppressive agents and histocompatibility matching. However, immunologic rejection remains the major cause of graft failure, particularly in patients with a high risk for rejection. Corticosteroids remain the first-line therapy for the prevention and treatment of immune rejection. However, current pharmacological measures are limited in their side-effect profiles, repeated application, lack of targeted response, and short duration of action. Experimental ocular gene therapy may thus present new horizons in immunomodulation. From efficient viral vectors to sustainable alternative splicing, we discuss the progress of gene therapy in promoting graft survival and postulate further avenues for gene-mediated prevention of allogeneic graft rejection.

Bacteriophage bionanowire as a carrier for both cancer-targeting peptides and photosensitizers and its use in selective cancer cell killing by photodynamic therapy

A photosensitizer, pyropheophorbid-a (PPa), is conjugated to SKBR-3 breast cancer cell-specific biological nanowire phage, to form a novel PPa-phage complex, which is further successfully used in selectively killing SKBR-3 breast cancer cells by the mechanism of photodynamic therapy (PDT).

Myocardial therapeutic angiogenesis: a review of the state of development and future obstacles

A significant percentage of patients have coronary artery disease that is too advanced or diffuse for percutaneous or surgical intervention. Therapeutic angiogenesis is a treatment modality to induce vessel formation that is being developed for patients with advanced coronary disease not amenable to currently available interventions. A number of approaches to induce coronary collateralization are being developed. These include gene, protein, cellular and miRNA modalities, each of which have advantages and disadvantages. At this time, no modality has emerged as the single clear choice, and combination therapies may provide synergistic benefits. However, there have been a number of recent studies advancing our knowledge as to how we can refine procollateralizing treatments. In this article, we will examine some recent successes and future obstacles in the effort to bring therapeutic angiogenesis to patients.

Liposome technology for cardiovascular disease treatment and diagnosis

INTRODUCTION

Over the past several decades, liposomes have been used in a variety of applications, from delivery vehicles to cell membrane models. In terms of pharmaceutical use, they can offer control over the release of active agents encapsulated into their lipid bilayer or aqueous core, while providing protection from degradation in the body. In addition, liposomes are versatile carriers, because targeting moieties can be conjugated on the surface to enhance delivery efficiency. It is for these reasons that liposomes have been applied as carriers for a multitude of drugs and genetic material, and as contrast agents, aimed to treat and diagnose cardiovascular diseases.

AREAS COVERED

This review details advancements in liposome technology used in the field of cardiovascular medicine. In particular, the application of liposomes to cardiovascular disease treatment and diagnosis, with a focus on delivering drugs, genetic material and improving cardiovascular imaging, will be explored. Advances in targeting liposomes to the vasculature will also be detailed.

EXPERT OPINION

Liposomes may provide the means to deliver drugs and other pharmaceutical agents for cardiovascular applications; however, there is still a vast amount of research and clinical trials that must be performed before a formulation is brought to market. Advancements in targeting abilities within the body, as well as the introduction of theranostic liposomes, capable of both delivering treating and imaging cardiac diseases, may be expected in the future of this burgeoning field.

Gene therapy for C-26 colon cancer using heparin-polyethyleneimine nanoparticle-mediated survivin T34A

BACKGROUND

Gene therapy provides a novel method for the prevention and treatment of cancer, but the clinical application of gene therapy is restricted, mainly because of the absence of an efficient and safe gene delivery system. Recently, we developed a novel nonviral gene carrier, ie, heparin-polyethyleneimine (HPEI) nanoparticles for this purpose.

METHODS AND RESULTS

HPEI nanoparticles were used to deliver plasmid-expressing mouse survivin-T34A (ms-T34A) to treat C-26 carcinoma in vitro and in vivo. According to the in vitro studies, HPEI nanoparticles could efficiently transfect the pGFP report gene into C-26 cells, with a transfection efficiency of 30.5% ± 2%. Moreover, HPEI nanoparticle-mediated ms-T34A could efficiently inhibit the proliferation of C-26 cells by induction of apoptosis in vitro. Based on the in vivo studies, HPEI nanoparticles could transfect the Lac-Z report gene into C-26 cells in vivo. Intratumoral injection of HPEI nanoparticle-mediated ms-T34A significantly inhibited growth of subcutaneous C-26 carcinoma in vivo by induction of apoptosis and inhibition of angiogenesis.

CONCLUSION

This research suggests that HPEI nanoparticle-mediated ms-T34A may have a promising role in C-26 colon carcinoma therapy.

Effect of hypoxia-inducible factor-1alpha gene therapy on walking performance in patients with intermittent claudication

BACKGROUND

Hypoxia-inducible factor-1α (HIF-1α) is a transcriptional regulatory factor that orchestrates cellular responses to hypoxia. It increases collateral vessel growth and blood flow in models of hind-limb ischemia. This study tested whether intramuscular administration of Ad2/HIF-1α/VP16, an engineered recombinant type 2 adenovirus vector encoding constitutively active HIF-1α, improves walking time in patients with peripheral artery disease and intermittent claudication.

METHODS AND RESULTS

Two hundred eighty-nine patients with claudication were randomized in a double-blind manner to 1 of 3 doses of Ad2/HIF-1α/VP16 (2×10(9), 2×10(10), or 2×10(11) viral particles) or placebo, administered by 20 intramuscular injections to each leg. Graded treadmill tests were performed at baseline and then 3, 6, and 12 months after treatment. The primary end point was the change in peak walking time from baseline to 6 months. The secondary end point was change in claudication onset time, and tertiary end points included changes in ankle-brachial index and quality-of-life assessments. Median peak walking time increased by 0.82 minutes (interquartile range, -0.05-1.93 minutes) in the placebo group and by 0.82 minutes (interquartile range, -0.07-2.12 minutes), 0.28 minutes (interquartile range, -0.37-1.70 minutes), and 0.78 minutes (interquartile range, -0.02-2.10 minutes) in the HIF-1α 2×10(9), 2×10(10), and 2×10(11) viral particle groups, respectively (P=NS between placebo and each HIF-1α treatment group). There were no significant differences in claudication onset time, ankle-brachial index, or quality-of-life measurements between the placebo and each HIF-1α group.

CONCLUSIONS

Gene therapy with intramuscular administration of Ad2/HIF-1α/VP16 is not an effective treatment for patients with intermittent claudication. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00117650.

Magnetic nanoparticles for targeted vascular delivery

Magnetic targeting has shown promise to improve the efficacy and safety of different classes of therapeutic agents by enabling their active guidance to the site of disease and minimizing dissemination to nontarget tissues. However, its translation into clinic has proven difficult because of inherent limitations of traditional approaches inapplicable for deep tissue targeting in human subjects and a need for developing well-characterized and fully biocompatible magnetic carrier formulations. A novel magnetic targeting scheme based on the magnetizing effect of deep-penetrating uniform fields is presented as an example of a strategy providing a potentially clinically viable solution for preventing injury-triggered reobstruction of stented blood vessels (in-stent restenosis). The design of optimized magnetic carrier formulations and experimental results showing the feasibility of uniform field-controlled targeting for site-specific vascular delivery of small-molecule pharmaceuticals, biotherapeutics, and cells are discussed in the context of antirestenotic therapy. The versatility of this approach applicable to different classes of therapeutic agents exerting their antirestenotic effects through distinct mechanisms prompts exploring the utility of uniform field-mediated magnetic stent targeting for combination therapies with enhanced efficiencies and improved safety profiles. Additional improvements in terms of site specificity and protracted carrier retention at the site of injury may be expected from the development and use of magnetic carriers exhibiting affinity for arterial wall-specific antigens.

ECM-based materials in cardiovascular applications: Inherent healing potential and augmentation of native regenerative processes

The in vivo healing process of vascular grafts involves the interaction of many contributing factors. The ability of vascular grafts to provide an environment which allows successful accomplishment of this process is extremely difficult. Poor endothelisation, inflammation, infection, occlusion, thrombosis, hyperplasia and pseudoaneurysms are common issues with synthetic grafts in vivo. Advanced materials composed of decellularised extracellular matrices (ECM) have been shown to promote the healing process via modulation of the host immune response, resistance to bacterial infections, allowing re-innervation and reestablishing homeostasis in the healing region. The physiological balance within the newly developed vascular tissue is maintained via the recreation of correct biorheology and mechanotransduction factors including host immune response, infection control, homing and the attraction of progenitor cells and infiltration by host tissue. Here, we review the progress in this tissue engineering approach, the enhancement potential of ECM materials and future prospects to reach the clinical environment.

Adenovirus-Mediated VEGF Gene Therapy Enhances Venous Thrombus Recanalization and Resolution

Objective— Rapid thrombus recanalization reduces the incidence of post–thrombotic complications. This study aimed to discover whether adenovirus-mediated transfection of the vascular endothelial growth factor gene (ad.VEGF) enhanced thrombus recanalization and resolution.

Methods and Results— In rats, thrombi were directly injected with either ad.VEGF (n=40) or ad.GFP (n=37). Thrombi in SCID mice (n=12) were injected with human macrophages transfected with ad.VEGF or ad.GFP. Thrombi were analyzed at 1 to 14 days. GFP was found mainly in the vein wall and adventitia by 3 days, but was predominantly found in cells within the body of thrombus by day 7. VEGF levels peaked at 4 days (376±299 pg/mg protein). Ad.VEGF treatment reduced thrombus size by >50% (47.7±5.1 mm 2 to 22.0±4.0 mm 2 , P =0.0003) and increased recanalization by >3-fold (3.9±0.69% to 13.6±4.1%, P =0.024) compared with controls. Ad.VEGF treatment increased macrophage recruitment into the thrombus by more than 50% ( P =0.002). Ad.VEGF-transfected macrophages reduced thrombus size by 30% compared with controls (12.3±0.89 mm 2 to 8.7±1.4 mm 2 , P =0.04) and enhanced vein lumen recanalization (3.39±0.34% to 5.07±0.57%, P =0.02).

Conclusion— Treatment with ad.VEGF enhanced thrombus recanalization and resolution, probably as a consequence of an increase in macrophage recruitment.

Antioxidant gene therapy for cardiovascular disease: current status and future perspectives

Excessive production of reactive oxygen species has been implicated to play an important role in a number of cardiovascular pathologies, including hypertension, atherosclerosis, myocardial infarction, ischemia/reperfusion injury, and restenosis after angioplasty or venous bypass grafting. The formation of reactive oxygen species is balanced out by antioxidant defenses, and augmenting this defense by antioxidant therapies could therefore provide a potential means to treat conditions in which the formation of reactive oxygen species exceeds the capability of natural protective mechanisms. In this review, we summarize the studies in which antioxidant gene therapy has been used successfully to treat cardiovascular diseases. We also discuss the current limitations of antioxidant gene therapy and envision future therapeutic targets and methodological approaches for an improved outcome.

Gene delivery to the vasculature mediated by low-titre adeno-associated virus serotypes 1 and 5

BACKGROUND

Vascular gene therapy requires safe and efficient gene transfer in vivo. Recombinant adeno-associated virus (AAV) is a promising viral vector but its use in the vasculature has produced conflicting results and serotypes other than AAV2 have not been intensively studied. We investigated the efficiency of alternative AAV serotypes for vascular gene delivery in vitro and in vivo.

METHODS

Vascular cell lines were transduced in vitro with AAV vectors. Rabbit carotid arteries were transduced with AAV1, 2 and 5 encoding enhanced green fluorescent protein (eGFP) ( approximately 1.4 x 10(9) DNAse-resistant particles (drp)). Gene transfer in vivo was assessed at 14 and 28 days. High-titre doses of AAV2 encoding beta-galactosidase in vivo were also studied.

RESULTS

In vitro, transgene expression was not observed in endothelial cells using AAV2 whereas the use of serotypes 1 and 5 resulted in detectable levels of transgene expression. Coronary artery smooth muscle cells (CASMCs) transduced with AAV2 demonstrated higher levels of GFP expression than AAV1 or 5. Transgene expression in vivo was noted using low-titre AAV1 and AAV5 ( approximately 1.4 x 10(9) drp) in the media and adventitia. Only delivery of AAV1eGFP resulted in neointimal formation (3/7 vessels examined), with transgene expression noted in the neointima. Transgene expression with AAV2 was not detected in any layer of the blood vessel wall using low titre ( approximately 10(9) drp). However, high-titre ( approximately 10(11) drp) AAV2 resulted in transduction of cells in the media and adventitia but not the endothelium.

CONCLUSIONS

AAV1 and AAV5 have advantages over AAV2 for vascular gene delivery at low titres.

Lentiviral vector-mediated SERCA2 gene transfer protects against heart failure and left ventricular remodeling after myocardial infarction in rats

Reduced expression of the SERCA2 gene impairs the calcium-handling and contractile functions of the heart. We developed an SERCA2 gene transfer system using lentiviral vectors, and examined the long-term effect of SERCA2 gene transfer in the rat ischemic heart failure model. A lentiviral vector containing the SERCA2 gene was infused into a rat heart by hypothermic intracoronary delivery 2 weeks after myocardial infarction (MI). The transduction efficiency was approximately 40%. Six months after transduction, echocardiogram and pressure-volume measurements revealed that the SERCA2 gene transfer had significantly protected against left ventricular (LV) dilation, and had improved systolic and diastolic function, resulting in reduction in mortality rates. The brain natriuretic peptide mRNA level showed a significantly decrease and the phosphorylation level of serine residue of phospholamban (PLN) showed an increase in the Lenti-SERCA2-transduced heart. Further, DNA microarray analysis disclosed that SERCA2 gene transfer had increased cardioprotective gene expression and lowered the expression of genes that are known to exacerbate heart failure. The SERCA2 gene was successfully integrated into the host heart, induced favorable molecular remodeling, prevented LV geometrical remodeling, and improved the survival rate. These results suggest that a strategy to compensate for reduced SERCA2 gene expression by lentiviral vectors serves as a positive inotropic, lucitropic, and cardioprotective therapy for post-MI heart failure.

Viral vector-mediated 12/15-lipoxygenase overexpression in vascular smooth muscle cells enhances inflammatory gene expression and migration

Increased expression and activity of 12/15-lipoxygenase (12/15-LO) in vascular smooth muscle cells (VSMCs) play a key role in the pathogenesis of diabetes and vascular complications. However, the consequences of 12/15-LO overexpression for VSMC migration and inflammatory gene expression are not known. In this study, 12/15-LO was overexpressed using adeno- and baculoviral vectors in human VSMC (HVSMCs) and proatherogenic responses compared with control enhanced green fluorescent protein (EGFP)-expressing cells. HVSMCs transduced with 12/15-LO viruses expressed high levels of enzymatically active protein and produced increased levels of the LO product, 12(S)-hydroxyeicosatetraenoic acid. 12/15-LO-overexpressing HVSMCs exhibited increased oxidant stress, activation of p38 mitogen-activated protein kinase, migration and inflammatory gene expression relative to HVSMCs expressing EGFP. Furthermore, inflammatory gene expression induced by 12/15-LO overexpression was abolished by anti-oxidants, siRNAs targeting p65 (nuclear factor-kappaB), or new-generation baculoviruses expressing inhibitory IkappaBalpha or IkappaBalpha superrepressor mutant. Thus, we have used novel viral vector delivery systems, including baculoviruses, for the first time to deliver foreign genes into VSMCs and thereby demonstrated that 12/15-LO overexpression increases oxidant stress, mitogen-activated protein kinase activation, migration and inflammatory genes in VSMCs and that NF-kappaB is a key downstream effector. Enhanced proatherogenic responses in VSMCs triggered by increased 12/15-LO levels under pathological conditions may contribute to vascular dysfunction.

Cardiovascular gene therapy: current status and therapeutic potential

Gene therapy is emerging as a potential treatment option in patients suffering from a wide spectrum of cardiovascular diseases including coronary artery disease, peripheral vascular disease, vein graft failure and in-stent restenosis. Thus far preclinical studies have shown promise for a wide variety of genes, in particular the delivery of genes encoding growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) to treat ischaemic vascular disease both peripherally and in coronary artery disease. VEGF as well as other genes such as TIMPs have been used to target the development of neointimal hyperplasia to successfully prevent vein graft failure and in-stent restenosis in animal models. Subsequent phase I trials to examine safety of these therapies have been successful with low levels of serious adverse effects, and albeit in the absence of a placebo group some suggestion of efficacy. Phase 2 studies, which have incorporated a placebo group, have not confirmed this early promise of efficacy. In the next generation of clinical gene therapy trials for cardiovascular disease, many parameters will need to be adjusted in the search for an effective therapy, including the identification of a suitable vector, appropriate gene or genes and an effective vector delivery system for a specific disease target. Here we review the current status of cardiovascular gene therapy and the potential for this approach to become a viable treatment option.

Gene Therapy for Cardiac Arrhythmias: A Dream Soon to Come True?

Alternatively, excitement and frustration have been generated from the literature reports of gene therapy for treatment and potential cure of cardiac diseases. The time since the first literature report of in vivo myocardial gene transfer is more than 15 years, and the time since the first report of gene therapy for a cardiac arrhythmia is six years. Clinical trials, let alone clinical usage, of these promising therapies have not yet started. This article reviews the current state of the art for arrhythmia gene therapy, including the literature reports of antiarrhythmic studies and of problems within the field. Gene transfer continues to be a promising technology, but patience is required as these problems are solved and the therapies make their way through the preclinical and clinical testing process.

Adenoviral gene vector tethering to nanoparticle surfaces results in receptor-independent cell entry and increased transgene expression

The present studies investigated the hypothesis that affinity immobilization of replication-defective adenoviruses (Ad) on the surfaces of biodegradable nanoparticles (NP) can improve transduction through uncoupling cellular uptake from the coxsackie-adenovirus receptor (CAR). Ad was tethered to the surfaces of polylactide-based NP that were surface-activated using a photoreactive polyallylamine-benzophenone-pyridyldithiocarboxylate polymer, which enabled (via thiol chemistry) the covalent attachment of Ad-binding proteins, either the recombinant D1 domain of CAR or an adenoviral knob-specific monoclonal antibody. Gene transfer by NP-Ad complexes was studied in relation to cellular uptake as a function of cell type and the character of NP-Ad binding. NP-Ad complexes, but not Ad applied with or without control nonimmune IgG-modified NP, significantly increased green fluorescent protein reporter expression in endothelioma and endothelial and arterial smooth muscle cells (SMC) in direct correlation to the extent of NP-Ad internalization. CAR-independent uptake of NP-Ad was confirmed by demonstrating inhibition of free Ad- but not NP-Ad complex-mediated transduction by knob protein. Complexes formulated with an Ad encoding inducible nitric oxide synthase inhibited growth of cultured SMC to a significantly greater extent than those with (GFP)Ad or (NULL)Ad or free vector. It is concluded that Ad-specific affinity tethering to biodegradable NP can significantly increase the level of gene expression via a CAR-independent uptake mechanism.

Viral gene therapy strategies: from basic science to clinical application

A major impediment to the successful application of gene therapy for the treatment of a range of diseases is not a paucity of therapeutic genes, but the lack of an efficient non-toxic gene delivery system. Having evolved to deliver their genes to target cells, viruses are currently the most effective means of gene delivery and can be manipulated to express therapeutic genes or to replicate specifically in certain cells. Gene therapy is being developed for a range of diseases including inherited monogenic disorders and cardiovascular disease, but it is in the treatment of cancer that this approach has been most evident, resulting in the recent licensing of a gene therapy for the routine treatment of head and neck cancer in China. A variety of virus vectors have been employed to deliver genes to cells to provide either transient (eg adenovirus, vaccinia virus) or permanent (eg retrovirus, adeno-associated virus) transgene expression and each approach has its own advantages and disadvantages. Paramount is the safety of these virus vectors and a greater understanding of the virus-host interaction is key to optimizing the use of these vectors for routine clinical use. Recent developments in the modification of the virus coat allow more targeted approaches and herald the advent of systemic delivery of therapeutic viruses. In the context of cancer, the ability of attenuated viruses to replicate specifically in tumour cells has already yielded some impressive results in clinical trials and bodes well for the future of this approach, particularly when combined with more traditional anti-cancer therapies.

Gene transfer for ischemic cardiovascular disease: is this the end of the beginning or the beginning of the end?

The past decade has represented a period of high expectations for cardiovascular gene transfer on the basis of the findings from preclinical experiments and promising early clinical results. Yet, randomized studies have not demonstrated similar results. Do these poor results mean that gene transfer for ischemic cardiovascular disease has failed in its promise, or do they merely signify the inherent challenges of a pioneering field? In this paper we briefly review the clinical experience of gene transfer for ischemic cardiovascular disease and propose future directions for research.

Tendon healing in vitro: bFGF gene transfer to tenocytes by adeno-associated viral vectors promotes expression of collagen genes

PURPOSE

Adeno-associated virus-mediated gene transfer is promising in the delivery of genes to tendons because this vector stimulates few adverse tissue reactions. Basic fibroblast growth factor (bFGF) promotes collagen production in healing tendons. We transferred the exogenous bFGF gene to proliferating tenocytes by adeno-associated viral (AAV) vectors and investigated its effects on the expression of the collagen genes in an in vitro tenocyte model.

METHODS

AAV2 vectors harboring the rat bFGF gene were constructed. Tenocytes were obtained from explant cultures of rat intrasynovial tendons and were distributed into 21 culture dishes and 8 wells. Tenocytes in 7 dishes were treated with AAV2 bFGF for 3 hours and then were cultured for 10 days. Tenocytes in 14 dishes (sham vector and nontreatment controls) did not receive the transgene. Efficiency of the gene transfer was evaluated by in situ beta-galactosidase staining in 8 wells after treatment with AAV2 lacZ. Expression of the target genes was assessed by reverse-transcription polymerase chain reactions with primers specifically amplifying the target genes. Expression of bFGF and type I and III collagen genes was determined by quantitative analysis of the polymerase chain reaction products.

RESULTS

Positive beta-galactosidase staining confirmed the effectiveness of AAV2-mediated gene delivery to tenocytes. The level of expression of the bFGF gene was increased significantly after gene transfer. Levels of expression of type I and III collagen genes after transfer of the exogenous bFGF gene were increased significantly compared with those in the cells treated with sham vectors or in nontreatment controls.

CONCLUSIONS

Delivery of exogenous bFGF gene to tenocytes can increase significantly the levels of expression of the bFGF and type I and III collagen genes. AAV2 vectors provide a novel method for delivering growth factor genes to tenocytes. These findings warrant future in vivo study of the delivery of genes pertinent to tendon healing through AAV2-based gene therapy to enhance repairs of injured flexor tendons.

Gene therapy in the cornea

Technological advances in the field of gene therapy has prompted more than three hundred phase I and phase II gene-based clinical trials for the treatment of cancer, AIDS, macular degeneration, cardiovascular, and other monogenic diseases. Besides treating diseases, gene transfer technology has been utilized for the development of preventive and therapeutic vaccines for malaria, tuberculosis, hepatitis A, B and C viruses, AIDS, and influenza. The potential therapeutic applications of gene transfer technology are enormous. The cornea is an excellent candidate for gene therapy because of its accessibility and immune-privileged nature. In the last two decades, various viral vectors, such as adeno, adeno-associated, retro, lenti, and herpes simplex, as well as non-viral methods, were examined for introducing DNA into corneal cells in vitro, in vivo and ex vivo. Most of these studies used fluorescent or non-fluorescent marker genes to track the level and duration of transgene expression in corneal cells. However, limited studies were directed to evaluate prospects of gene-based interventions for corneal diseases or disorders such as allograft rejection, laser-induced post-operative haze, herpes simplex keratitis, and wound healing in animal models. We will review the successes and obstacles impeding gene therapy approaches used for delivering genes into the cornea.

Cell-selective viral gene delivery vectors for the vasculature

Clinical gene therapy for cardiovascular disease remains achievable. To date, however, preclinical studies and clinical trials have highlighted shortfalls in viral gene delivery to vascular cells. These include poor efficiency, poor target tissue selectivity, the presence of pre-existing neutralizing antibodies and immunogenicity generated by the host to vectors such as adenovirus. These important issues require careful consideration when applying viral vectors for gene therapy. Each delivery vector requires precise optimization and tailoring for each disease application since parameters relating to vector : tissue exposure time, route of delivery and target cell type vary considerably. Optimization can be achieved through modification of the structure of the virus capsid proteins and expression cassette to generate vectors that are highly selective and efficient for target cell binding and entry as well as instilling transcriptional control and/or longevity on transgene expression. This ultimately will improve the efficacy and toxicity profiles of gene delivery vectors and has become a very important area in gene therapy. Here, we review recent advances in the targeting of viral gene delivery vectors to the vasculature.

Nonviral DNA vectors for immunization and therapy: design and methods for their obtention

The use of plasmid DNA for vaccination and therapy is a relatively novel technology, with advantages and limitations as with other gene transfer techniques. The technology is based on DNA vectors designed for administering genes coding for relevant proteins into a given organism, fulfilling requirements of the regulatory agencies that once properly formulated and delivered the desired vaccine/therapeutic effect can be achieved. Starting from conventional plasmid DNA vectors currently tested in clinical trials, improvement resulted in bacterial element-less vectors, increasing the complexity of the developmental process. The present review focuses on systems described for generating these nonviral DNA vectors for immunization and therapy from bacterial hosts (conventional and conditionally replicating plasmids, nonreplicating minicircles, and linear dumbbell-shaped expression cassettes) in vivo or in vitro. Additionally, nontherapeutic genetic sequences with a negative or positive effect according to the specific application are described, bringing a better comprehension of the technology's state of the art.