Nonviral gene therapy targeting cardiovascular system

Advancements in gene therapy approaches for atrial fibrillation: Targeted delivery, mechanistic insights and future prospects

Atrial fibrillation (AF) remains a complex and challenging arrhythmia to treat, necessitating innovative therapeutic strategies. This review explores the evolving landscape of gene therapy for AF, focusing on targeted delivery methods, mechanistic insights, and future prospects. Direct myocardial injection, reversible electroporation, and gene painting techniques are discussed as effective means of delivering therapeutic genes, emphasizing their potential to modulate both structural and electrical aspects of the AF substrate. The importance of identifying precise targets for gene therapy, particularly in the context of AF-associated genetic, structural, and electrical abnormalities, is highlighted. Current studies employing animal models, such as mice and large animals, provide valuable insights into the efficacy and limitations of gene therapy approaches. The significance of imaging methods for detecting atrial fibrosis and guiding targeted gene delivery is underscored. Activation mapping techniques offer a nuanced understanding of AF-specific mechanisms, enabling tailored gene therapy interventions. Future prospects include the integration of advanced imaging, activation mapping, and percutaneous catheter-based techniques to refine transendocardial gene delivery, with potential applications in both ventricular and atrial contexts. As gene therapy for AF progresses, bridging the translational gap between preclinical models and clinical applications is imperative for the successful implementation of these promising approaches.

Gene therapy vector-related myocarditis

Gene therapy is a technique to correct genetic abnormalities, through introduction of a functional gene or through direct genome editing. Adeno-associated virus (AAV)-mediated gene replacement shows promise for targeted therapies in treatment of inherited cardiomyopathies and is the most used approach in clinical trials. However, immune responses from the host to the virus and gene product pose delivery and safety challenges. This review explores the immunological reactions to AAV-based gene therapy, their potential toxic effects, with a focus on myocarditis, and future directions for gene therapy.

Applications of Gene Therapy in Cardiomyopathies

Gene therapy is defined by the introduction of new genes or the genetic modification of existing genes and/or their regulatory portions via gene replacement and gene editing strategies, respectively. The genetic material is usually delivered though cardiotropic vectors such as adeno-associated virus 9 or engineered capsids. The enthusiasm for gene therapy has been hampered somewhat by adverse events observed in clinical trials, including dose-dependent immunologic reactions such as hepatotoxicity, acquired hemolytic uremic syndrome and myocarditis. Notably, gene therapy for Duchenne muscular dystrophy has recently been approved and pivotal clinical trials are testing gene therapy approaches in rare myocardial conditions such as Danon disease and Fabry disease. Furthermore, promising results have been shown in animal models of gene therapy in hypertrophic cardiomyopathy and arrhythmogenic cardiomyopathy. This review summarizes the gene therapy techniques, the toxicity risk associated with adeno-associated virus delivery, the ongoing clinical trials, and future targets.

Current Landscape of Gene Therapy for the Treatment of Cardiovascular Disorders

Cardiovascular disorders (CVD) are the primary cause of death worldwide. Multiple factors have been accepted to cause cardiovascular diseases; among them, smoking, physical inactivity, unhealthy eating habits, age, and family history are flag-bearers. Individuals at risk of developing CVD are suggested to make drastic habitual changes as the primary intervention to prevent CVD; however, over time, the disease is bound to worsen. This is when secondary interventions come into play, including antihypertensive, anti-lipidemic, anti-anginal, and inotropic drugs. These drugs usually undergo surgical intervention in patients with a much higher risk of heart failure. These therapeutic agents increase the survival rate, decrease the severity of symptoms and the discomfort that comes with them, and increase the overall quality of life. However, most individuals succumb to this disease. None of these treatments address the molecular mechanism of the disease and hence are unable to halt the pathological worsening of the disease. Gene therapy offers a more efficient, potent, and important novel approach to counter the disease, as it has the potential to permanently eradicate the disease from the patients and even in the upcoming generations. However, this therapy is associated with significant risks and ethical considerations that pose noteworthy resistance. In this review, we discuss various methods of gene therapy for cardiovascular disorders and address the ethical conundrum surrounding it.

Hyaluronic acid-functionalized lipoplexes and polyplexes as emerging nanocarriers for receptor-targeted cancer therapy

Cancer is an intricate disease that develops as a response to a combination of hereditary and environmental risk factors, which then result in a variety of changes to the genome. The cluster of differentiation (CD44) is a type of transmembrane glycoprotein that serves as a potential biomarker for cancer stem cells (CSC) and viable targets for therapeutic intervention in the context of cancer therapy. Hyaluronic acid (HA) is a linear polysaccharide that exhibits a notable affinity for the CD44 receptor. This characteristic renders it a promising candidate for therapeutic interventions aimed at selectively targeting CD44-positive cancer cells. Treating cancer via non-viral vector-based gene delivery has changed the notion of curing illness through the incorporation of therapeutic genes into the organism. The objective of this review is to provide an overview of various hyaluronic acid-modified lipoplexes and polyplexes as potential drug delivery methods for specific forms of cancer by effectively targeting CD44.

Gene Therapy for Cardiomyocyte Renewal: Cell Cycle, a Potential Therapeutic Target

Heart disease is the primary cause of death worldwide. Even though extensive research has been done, and many pharmacological and surgical treatments have been introduced to treat heart disease, the mortality rate still remains high. Gene therapy is widely used to understand molecular mechanisms of myocardial infarction and to treat cardiomyocyte loss. It was reported that adult cardiomyocytes proliferate at a very low rate; thus, targeting their proliferation has become a new regenerative therapeutic approach. Currently, re-activating cardiomyocyte proliferation appears to be one of the most promising methods to promote adult cardiomyocyte renewal. In this article, we highlight gene therapeutic targets of cell proliferation presently being pursued to re-activate the cell cycle of cardiomyocytes, including cell cycle regulators, transcription factors, microRNAs, signal transduction, and other contributing factors. We also summarize gene delivery vectors that have been used in cardiac research and major challenges to be overcome in the translation to the clinical approach and future directions.

Nucleic acid therapies for CNS diseases: Pathophysiology, targets, barriers, and delivery strategies

Nucleic acid therapeutics have emerged as one of the very advanced and efficacious treatment approaches for debilitating health conditions, including those diseases affecting the central nervous system (CNS). Precise targeting with an optimal control over gene regulation confers long-lasting benefits through the administration of nucleic acid payloads via viral, non-viral, and engineered vectors. The current review majorly focuses on the development and clinical translational potential of non-viral vectors for treating CNS diseases with a focus on their specific design and targeting approaches. These carriers must be able to surmount the various intracellular and extracellular barriers, to ensure successful neuronal transfection and ultimately attain higher therapeutic efficacies. Additionally, the specific challenges associated with CNS administration also include the presence of blood-brain barrier (BBB), the complex pathophysiological and biochemical changes associated with different disease conditions and the existence of non-dividing cells. The advantages offered by lipid-based or polymeric systems, engineered proteins, particle-based systems coupled with various approaches of neuronal targeting have been discussed in the context of a variety of CNS diseases. The possibilities of rapid yet highly efficient gene modifications rendered by the breakthrough methodologies for gene editing and gene manipulation have also opened vast avenues of research in neuroscience and CNS disease therapy. The current review also underscores the extensive scientific efforts to optimize specialized, efficacious yet non-invasive and safer administration approaches to overcome the therapeutic delivery challenges specifically posed by the CNS transport barriers and the overall obstacles to clinical translation.

Gene therapy to terminate tachyarrhythmias

INTRODUCTION

To date, the treatment option for tachyarrhythmia is classified into drug therapy, catheter ablation, and implantable device therapy. However, the efficacy of the antiarrhythmic drugs is limited. Although the indication of catheter ablation is expanding, several fatal tachyarrhythmias are still refractory to ablation. Implantable cardioverter-defibrillator increases survival, but it is not a curable treatment. Therefore, a novel therapy for tachyarrhythmias refractory to present treatments is desired. Gene therapy is being developed as a promising candidate for this purpose, and basic research and translational research have been accumulated in recent years.

AREAS COVERED

This paper reviews the current state of gene therapy for arrhythmias, including susceptible arrhythmias, the route of administration to the heart, and the type of vector to use. We also discuss the latest progress in the technology of gene delivery and genome editing.

EXPERT OPINION

Gene therapy is one of the most promising technologies for arrhythmia treatment. However, additional technological innovation to achieve safe, localized, homogeneous, and long-lasting gene transfer is required for its clinical application.

Gemini surfactant-based nanoparticles T-box1 gene delivery as a novel approach to promote epithelial stem cells differentiation and dental enamel formation

Enamel is the highest mineralized tissue in the body protecting teeth from external stimuli, infections, and injuries. Enamel lacks the ability to self-repair due to the absence of enamel-producing cells in the erupted teeth. Here, we reported a novel approach to promote enamel-like tissue formation via the delivery of a key ameloblast inducer, T-box1 gene, into a rat dental epithelial stem cell line, HAT-7, using non-viral gene delivery systems based on cationic lipids. We comparatively assessed the lipoplexes prepared from glycyl-lysine-modified gemini surfactants and commercially available 1,2-dioleoyl-3-trimethylammonium-propane lipids at three nitrogen-to phosphate (N/P) ratios of 2.5, 5 and 10. Our findings revealed that physico-chemical characteristics and biological activities of the gemini surfactant-based lipoplexes with a N/P ratio of 5 provide the most optimal outcomes among those examined. HAT-7 cells were transfected with T-box1 gene using the optimal formulation then cultured in conventional 2D cell culture systems. Ameloblast differentiation, mineralization, bio-enamel interface and structure were assessed at different time points over 28 days. Our results showed that our gemini transfection system provides superior gene expression compared to the benchmark agent, while keeping low cytotoxicity levels. T-box1-transfected HAT-7 cells strongly expressed markers of secretory and maturation stages of the ameloblasts, deposited minerals, and produced enamel-like crystals when compared to control cells. Taken together, our gemini surfactant-based T-box1 gene delivery system is effective to accelerate and guide ameloblastic differentiation of dental epithelial stem cells and promote enamel-like tissue formation. This study would represent a significant advance towards the tissue engineering and regeneration of dental enamel.

Recent advances in gene therapy for atrial fibrillation

Atrial fibrillation (AF) is the most common heart rhythm disorder in adults and a major cause of stroke. Unfortunately, current treatments for AF are suboptimal as they are not targeting the molecular mechanisms underlying AF. In this regard, gene therapy is emerging as a promising approach for mechanism-based treatment of AF. In this review, we summarize recent advances and challenges in gene therapy for this important cardiovascular disease.

Focus on the Lymphatic Route to Optimize Drug Delivery in Cardiovascular Medicine

While oral agents have been the gold standard for cardiovascular disease therapy, the new generation of treatments is switching to other administration options that offer reduced dosing frequency and more efficacy. The lymphatic network is a unidirectional and low-pressure vascular system that is responsible for the absorption of interstitial fluids, molecules, and cells from the peripheral tissue, including the skin and the intestines. Targeting the lymphatic route for drug delivery employing traditional or new technologies and drug formulations is exponentially gaining attention in the quest to avoid the hepatic first-pass effect. The present review will give an overview of the current knowledge on the involvement of the lymphatic vessels in drug delivery in the context of cardiovascular disease.

Ultrasonic microbubble VEGF gene delivery improves angiogenesis of senescent endothelial progenitor cells

The therapeutic effects of ultrasonic microbubble transfection (UMT)-based vascular endothelial growth factor 165 (VEGF165) gene delivery on young and senescent endothelial progenitor cells (EPCs) were investigated. By UMT, plasmid DNA (pDNA) can be delivered into both young EPCs and senescent EPCs. In the UMT groups, higher pDNA-derived protein expression was found in senescent EPCs than in young EPCs. Consistent with this finding, a higher intracellular level of pDNA copy number was detected in senescent EPCs, with a peak at the 2-h time point post UMT. Ultrasonic microbubble delivery with or without VEGF improved the angiogenic properties, including the proliferation and/or migration activities, of senescent EPCs. Supernatants from young and senescent EPCs subjected to UMT-mediated VEGF transfection enhanced the proliferation and migration of human aortic endothelial cells (HAECs), and the supernatant of senescent EPCs enhanced proliferation more strongly than the supernatant from young EPCs. In the UMT groups, the stronger enhancing effect of the supernatant from senescent cells on HAEC proliferation was consistent with the higher intracellular VEGF pDNA copy number and level of protein production per cell in the supernatant from senescent cells in comparison to the supernatant from young EPCs. Given that limitations for cell therapies are the inadequate number of transplanted cells and/or insufficient cell angiogenesis, these findings provide a foundation for enhancing the therapeutic angiogenic effect of cell therapy with senescent EPCs in ischaemic cardiovascular diseases.

Non-viral Gene Delivery Methods for Bone and Joints

Viral carrier transport efficiency of gene delivery is high, depending on the type of vector. However, viral delivery poses significant safety concerns such as inefficient/unpredictable reprogramming outcomes, genomic integration, as well as unwarranted immune responses and toxicity. Thus, non-viral gene delivery methods are more feasible for translation as these allow safer delivery of genes and can modulate gene expression transiently both in vivo, ex vivo, and in vitro. Based on current studies, the efficiency of these technologies appears to be more limited, but they are appealing for clinical translation. This review presents a summary of recent advancements in orthopedics, where primarily bone and joints from the musculoskeletal apparatus were targeted. In connective tissues, which are known to have a poor healing capacity, and have a relatively low cell-density, i.e., articular cartilage, bone, and the intervertebral disk (IVD) several approaches have recently been undertaken. We provide a brief overview of the existing technologies, using nano-spheres/engineered vesicles, lipofection, and in vivo electroporation. Here, delivery for microRNA (miRNA), and silencing RNA (siRNA) and DNA plasmids will be discussed. Recent studies will be summarized that aimed to improve regeneration of these tissues, involving the delivery of bone morphogenic proteins (BMPs), such as BMP2 for improvement of bone healing. For articular cartilage/osteochondral junction, non-viral methods concentrate on targeted delivery to chondrocytes or MSCs for tissue engineering-based approaches. For the IVD, growth factors such as GDF5 or GDF6 or developmental transcription factors such as Brachyury or FOXF1 seem to be of high clinical interest. However, the most efficient method of gene transfer is still elusive, as several preclinical studies have reported many different non-viral methods and clinical translation of these techniques still needs to be validated. Here we discuss the non-viral methods applied for bone and joint and propose methods that can be promising in clinical use.

Gene therapy for cardiovascular diseases in China: basic research

Cardiovascular disease has become a major disease affecting health in the whole world. Gene therapy, delivering foreign normal genes into target cells to repair damages caused by defects and abnormal genes, shows broad prospects in treating different kinds of cardiovascular diseases. China has achieved great progress of basic gene therapy researches and pathogenesis of cardiovascular diseases in recent years. This review will summarize the latest research about gene therapy of proteins, epigenetics, including noncoding RNAs and genome-editing technology in myocardial infarction, cardiac ischemia-reperfusion injury, atherosclerosis, muscle atrophy, and so on in China. We wish to highlight some important findings about the essential roles of basic gene therapy in this field, which might be helpful for searching potential therapeutic targets for cardiovascular disease.

Gene therapy for atrial fibrillation - How close to clinical implementation?

In this review we examine the current state of gene therapy for the treatment of cardiac arrhythmias. We describe advances and challenges in successfully creating and incorporating gene vectors into the myocardium. After summarizing the current scientific research in gene transfer technology we then focus on the most promising areas of gene therapy, the treatment of atrial fibrillation and ventricular tachyarrhythmias. We review the scientific literature to determine how gene therapy could potentially be used to treat patients with cardiac arrhythmias.

Liver gene transfection by retrograde intrabiliary infusion facilitated by temporary biliary obstruction

BACKGROUND

The hepatobiliary tract may be a valuable administration site for gene delivery. We demonstrated the role of temporary biliary obstruction for gene transfection by retrograde intrabiliary infusion.

METHODS

Male Sprague-Dawley rats received intrabiliary infusion of luciferase plasmid via an artificial common bile duct, with temporary biliary obstruction for 0 minutes (NO group), 30 minutes (30 min group) and 24 hours (24 h group), respectively (n = 4 for each group). Gene expression levels were evaluated by luciferase bioluminescence on postoperative days (POD) 1, 2 and 7. Serum and livers were collected on POD 1 and 14 for liver biochemistry, hematoxylin and eosin staining, and immunohistochemistry.

RESULTS

On POD 1, luciferase chemoluminescence was significantly higher in the 24 h group than in the NO group (p = 0.002) and the 30 min group (p = 0.002). However, it decreased rapidly after reversal of the obstruction in the 24 h group (POD 1 versus POD 2, p = 0.002; POD 1 versus POD 7, p = 0.002). Liver biochemistry was changed on POD 1, but no significant differences were detected after 14 days of recovery (p > 0.05). Similar histological changes were found in the three groups, with no unwanted proliferation of biliary epithelial cells. The obstruction did not cause serious liver damage.

CONCLUSIONS

Temporary biliary obstruction for 24 hours facilitated the safe, feasible and effective transfection of plasmid DNA into the liver via the hepatobiliary tract. In the future, endoscopic retrograde cholangiopancreatography and its dilation balloon could be used to create biliary obstruction and allow the direct gene delivery into the liver. More research is necessary for achieving stable gene expression, as well as in terms of weighing its benefits against potential complications.

Enhanced Proliferation of Endothelial Progenitor Cells Post-Ultrasonic Microbubble Transfection Is Plasmid DNA Size Dependent and Contributed by Interleukin-6 Generation

We investigated whether ultrasonic microbubble transfection (UMT) would enhance the transfection of large-sized luciferase plasmids (5.6, 9.2 and 33 kb) and biological impacts. Porcine venous blood endothelial progenitor cells (EPCs) were cultured in a medium containing plasmid DNA (pDNA) of different sizes followed by UMT and functional assays. Real-time polymerase chain reaction was conducted to investigate the effects of transfection of pDNA on multiple molecules central to endothelial function. The results indicated enhanced luciferase expression after UMT but the enhancement declined with increase in the size of the plasmid. UMT of pDNAs sized 5.6 and 9.2 kb into EPCs led to significant enhancement of proliferation. The interleukin-6 (IL-6) secreted from UMT of EPCs also increased in the 5.6- and 9.2-kb pDNA groups. Treatment of the transfected EPCs with anti-IL-6 antibody neutralized the proliferation. In conclusion, UMT of pDNAs sized 5.6 and 9.2 kb into EPCs increased the secretion of IL-6, which in turn enhanced cell proliferation.

Non-Viral Vectors for Gene Delivery

Introduction:

Gene therapy has emerged out as a promising therapeutic pave for the treatment of genetic and acquired diseases. Gene transfection into target cells using naked DNA is a simple and safe approach which has been further improved by combining vectors or gene carriers. Both viral and non-viral approaches have achieved a milestone to establish this technique, but non-viral approaches have attained a significant attention because of their favourable properties like less immunotoxicity and biosafety, easy to produce with versatile surface modifications, etc. Literature is rich in evidences which revealed that undoubtedly, non–viral vectors have acquired a unique place in gene therapy but still there are number of challenges which are to be overcome to increase their effectiveness and prove them ideal gene vectors.

Conclusion:

To date, tissue specific expression, long lasting gene expression system, enhanced gene transfection efficiency has been achieved with improvement in delivery methods using non-viral vectors. This review mainly summarizes the various physical and chemical methods for gene transfer in vitro and in vivo.

Gene Therapy for the Treatment of Cardiac Arrhythmias: Current and Emerging Applications

In this review, we examine the current state of gene therapy for the treatment of cardiac arrhythmias. We describe advances and challenges in successfully creating and incorporating gene vectors into the myocardium. After summarizing the current scientific research in gene transfer technology, we then focus on the most promising areas of gene therapy at this time, which is the treatment of atrial fibrillation and ventricular tachyarrhythmias. We also review the scientific literature to determine how gene therapy could potentially be used to treat patients with cardiac arrhythmias.

Nonviral Gene Therapy for Cancer: A Review

Although the development of effective viral vectors put gene therapy on the road to commercialization, nonviral vectors show promise for practical use because of their relative safety and lower cost. A significant barrier to the use of nonviral vectors, however, is that they have not yet proven effective. This apparent lack of interest can be attributed to the problem of the low gene transfer efficiency associated with nonviral vectors. The efficiency of gene transfer via nonviral vectors has been reported to be 1/10th to 1/1000th that of viral vectors. Despite the fact that new gene transfer methods and nonviral vectors have been developed, no significant improvements in gene transfer efficiency have been achieved. Nevertheless, some notable progress has been made. In this review, we discuss studies that report good results using nonviral vectors in vivo in animal models, with a particular focus on studies aimed at in vivo gene therapy to treat cancer, as this disease has attracted the interest of researchers developing nonviral vectors. We describe the conditions in which nonviral vectors work more efficiently for gene therapy and discuss how the goals might differ for nonviral versus viral vector development and use.

Gene delivery system of pDNA using the blood glycoprotein fetuin

Fetuin is a biocompatible plasma protein and strongly enhances phagocytosis of bacteria, DNA and apoptotic cells by peripheral blood cells such as monocytes, macrophages and dendritic cells. We developed a novel gene delivery system: ternary complexes constructed with pDNA, polyethylenimine (PEI) and fetuin. Without covalent binding, fetuin was able to coat pDNA-PEI complexes, and stable anionic nanoparticles formed at a weight ratio greater than 30. Optimised pDNA-PEI-fetuin complexes significantly decreased the cytotoxicity of pDNA-PEI complexes in the melanoma cell line B16F10. Furthermore, the pDNA-PEI-fetuin complexes had higher transgene efficiency compared to that of commercial lipofectin previously reported in B16F10 cells despite an anionic surface. The pDNA-PEI-fetuin complexes did not agglutinate with erythrocytes. The pDNA-PEI-fetuin complexes had high gene expression in the spleen after intravenous administration in mice. Thus, the pDNA-PEI-fetuin complexes were a useful in vivo gene delivery system with tropism for the spleen.

Current Methods in Cardiac Gene Therapy: Overview

During the last decade, there has been a significant progress toward clinical translation in the field of cardiac gene therapy based on extensive preclinical data. However, despite encouraging positive results in early phase clinical trials, more recent larger trials reported only neutral results. Nevertheless, the field has gained important knowledge from these trials and is leading to the development of more cardiotropic vectors and improved delivery systems. It has become more evident that humans are more resistant to therapeutic transgene expression compared to experimental animals and thus refinement in gene delivery tools and methods are essential for future success. We provide an overview of the current status of cardiac gene therapy focusing on gene delivery tools and methods. Newer technologies, devices, and approaches will undoubtedly lead to more promising clinical results in the near future.

Ultrasound-Targeted Microbubble Destruction for Cardiac Gene Delivery

Ultrasound targeted microbubble destruction (UTMD) is a novel technique that is used to deliver a gene or other bioactive substance to organs of living animals in a noninvasive manner. Plasmid DNA binding with cationic liposome into nanoparticles are assembled into the shell of microbubbles, which are circulated by intravenous injection. Intermittent bursts of ultrasound with low frequency and high mechanical index destroys the microbubbles and releases the nanoparticles into targeted organ to transfect local organ cells. Cell-specific promoters can be used to further enhance cell specificity. Here we describe UTMD applied to cardiac gene delivery.

Gene therapy for cardiovascular disease: advances in vector development, targeting, and delivery for clinical translation

Gene therapy is a promising modality for the treatment of inherited and acquired cardiovascular diseases. The identification of the molecular pathways involved in the pathophysiology of heart failure and other associated cardiac diseases led to encouraging preclinical gene therapy studies in small and large animal models. However, the initial clinical results yielded only modest or no improvement in clinical endpoints. The presence of neutralizing antibodies and cellular immune responses directed against the viral vector and/or the gene-modified cells, the insufficient gene expression levels, and the limited gene transduction efficiencies accounted for the overall limited clinical improvements. Nevertheless, further improvements of the gene delivery technology and a better understanding of the underlying biology fostered renewed interest in gene therapy for heart failure. In particular, improved vectors based on emerging cardiotropic serotypes of the adeno-associated viral vector (AAV) are particularly well suited to coax expression of therapeutic genes in the heart. This led to new clinical trials based on the delivery of the sarcoplasmic reticulum Ca²⁺-ATPase protein (SERCA2a). Though the first clinical results were encouraging, a recent Phase IIb trial did not confirm the beneficial clinical outcomes that were initially reported. New approaches based on S100A1 and adenylate cyclase 6 are also being considered for clinical applications. Emerging paradigms based on the use of miRNA regulation or CRISPR/Cas9-based genome engineering open new therapeutic perspectives for treating cardiovascular diseases by gene therapy. Nevertheless, the continuous improvement of cardiac gene delivery is needed to allow the use of safer and more effective vector doses, ultimately bringing gene therapy for heart failure one step closer to reality.

Non viral vectors in gene therapy- an overview

Non-viral vectors are simple in theory but complex in practice. Apart from intra cellular and extracellular barriers, number of other challenges also needs to be overcome in order to increase the effectiveness of non-viral gene transfer. These barriers are categorized as production, formulation and storage. No one-size-fits-all solution to gene delivery, which is why in spite of various developments in liposome, polymer formulation and optimization, new compounds are constantly being proposed and investigated. In this review, we will see in detail about various types of non-viral vectors highlighting promising development and recent advances that had improved the non-viral gene transfer efficiency of translating from "Bench to bedside".

Adeno-associated virus-mediated cancer gene therapy: current status

Gene therapy is one of the frontiers of modern medicine. Adeno-associated virus (AAV)-mediated gene therapy is becoming a promising approach to treat a variety of diseases and cancers. AAV-mediated cancer gene therapies have rapidly advanced due to their superiority to other gene-carrying vectors, such as the lack of pathogenicity, the ability to transfect both dividing and non-dividing cells, low host immune response, and long-term expression. This article reviews and provides up to date knowledge on AAV-mediated cancer gene therapy.

Secure and effective gene delivery system of plasmid DNA coated by polynucleotide

Polynucleotides are anionic macromolecules which are expected to transfer into the targeted cells through specific uptake mechanisms. So, we developed polynucleotides coating complexes of plasmid DNA (pDNA) and polyethylenimine (PEI) for a secure and efficient gene delivery system and evaluated their usefulness. Polyadenylic acid (polyA), polyuridylic acid (polyU), polycytidylic acid (polyC), and polyguanylic acid (polyG) were examined as the coating materials. pDNA/PEI/polyA, pDNA/PEI/polyU, and pDNA/PEI/polyC complexes formed nanoparticles with a negative surface charge although pDNA/PEI/polyG was aggregated. The pDNA/PEI/polyC complex showed high transgene efficiency in B16-F10 cells although there was little efficiency in pDNA/PEI/polyA and pDNA/PEI/polyU complexes. An inhibition study strongly indicated the specific uptake mechanism of pDNA/PEI/polyC complex. Polynucleotide coating complexes had lower cytotoxicity than pDNA/PEI complex. The pDNA/PEI/polyC complex showed high gene expression selectively in the spleen after intravenous injection into mice. The pDNA/PEI/polyC complex showed no agglutination with erythrocytes and no acute toxicity although these were observed in pDNA/PEI complex. Thus, we developed polynucleotide coating complexes as novel vectors for clinical gene therapy, and the pDNA/PEI/polyC complex as a useful candidate for a gene delivery system.

Anti-inflammatory loaded poly-lactic glycolic acid nanoparticle formulations to enhance myocardial gene transfer: an in-vitro assessment of a drug/gene combination therapeutic approach for direct injection

Background

Cardiac gene therapy for heart disease is a major translational research area with potential, yet problems with safe and efficient gene transfer into cardiac muscle remain unresolved. Existing methodology to increase vector uptake include modifying the viral vector, non-viral particle encapsulation and or delivery with device systems. These advanced methods have made improvements, however fail to address the key problem of inflammation in the myocardium, which is known to reduce vector uptake and contribute to immunogenic adverse events. Here we propose an alternative method to co-deliver anti-inflammatory drugs in a controlled release polymer with gene product to improve therapeutic effects.

Methods

A robust, double emulsion production process was developed to encapsulate drugs into nanoparticles. Briefly in this proof of concept study, aspirin and prednisolone anti-inflammatory drugs were encapsulated in various poly-lactic glycolic acid polymer (PLGA) formulations. The resultant particle systems were characterized, co-delivered with GFP plasmid, and evaluated in harvested myocytes in culture for uptake.

Results

High quality nanoparticles were harvested from multiple production runs, with an average 64 ± 10 mg yield. Four distinct particle drug system combinations were characterized and evaluated in vitro: PLGA(50:50) Aspirin, PLGA(65:35) Prednisolone, PLGA(65:35) Aspirin and PLGA(50:50) Prednisolone Particles consisted of spherical shape with a narrow size distribution 265 ± 104 nm as found in scanning electron microscopy imaging. Prednisolone particles regardless of PLGA type were found on average ≈ 100 nm smaller than the aspirin types. All four groups demonstrated high zeta potential stability and re-constitution testing prior to in vitro. In vitro results demonstrated co uptake of GFP plasmid (green) and drug loaded particles (red) in culture with no incidence of toxicity.

Conclusions

Nano formulated anti-inflammatories in combination with standalone gene product therapy may offer a clinical solution to maximize cardiac gene therapy product effects while minimizing the risk of the host response in the inflammatory myocardial environment.

Pleiotropic functions of magnetic nanoparticles for ex vivo gene transfer

Gene transfer technique has various applications, ranging from cellular biology to medical treatments for diseases. Although nonviral vectors, such as episomal vectors, have been developed, it is necessary to improve their gene transfer efficacy. Therefore, we attempted to develop a highly efficient gene delivery system combining an episomal vector with magnetic nanoparticles (MNPs). In comparison with the conventional method using transfection reagents, polyethylenimine-coated MNPs introduced episomal vectors more efficiently under a magnetic field and could express the gene in mammalian cells with higher efficiency and for longer periods. This novel in vitro separation method of gene-introduced cells utilizing the magnetic property of MNPs significantly facilitated the separation of cells of interest. Transplanted cells in vivo were detected using magnetic resonance. These results suggest that MNPs play multifunctional roles in ex vivo gene transfer, such as improvement of gene transfer efficacy, separation of cells, and detection of transplanted cells.

FROM THE CLINICAL EDITOR

This study convincingly demonstrates enhanced efficiency of gene transfer via magnetic nanoparticles. The method also enables magnetic sorting of cells positive for the transferred gene, and in vivo monitoring of the process with MRI.

Non-viral gene therapy for bone tissue engineering

The possibilities of using gene therapy for bone regeneration have been extensively investigated. Improvements in the design of new transfection agents, combining vectors and delivery/release systems to diminish cytotoxicity and increase transfection efficiencies have led to several successful in vitro, ex vivo and in vivo strategies. These include growth factor or short interfering ribonucleic acid (siRNA) delivery, or even enzyme replacement therapies, and have led to increased osteogenic differentiation and bone formation in vivo. These results provide optimism to consider use in humans with some of these gene-delivery strategies in the near future.

Gene therapy for cardiovascular disease mediated by ultrasound and microbubbles

Gene therapy provides an efficient approach for treatment of cardiovascular disease. To realize the therapeutic effect, both efficient delivery to the target cells and sustained expression of transgenes are required. Ultrasound targeted microbubble destruction (UTMD) technique has become a potential strategy for target-specific gene and drug delivery. When gene-loaded microbubble is injected, the ultrasound-mediated microbubble destruction may spew the transported gene to the targeted cells or organ. Meanwhile, high amplitude oscillations of microbubbles increase the permeability of capillary and cell membrane, facilitating uptake of the released gene into tissue and cell. Therefore, efficiency of gene therapy can be significantly improved. To date, UTMD has been successfully investigated in many diseases, and it has achieved outstanding progress in the last two decades. Herein, we discuss the current status of gene therapy of cardiovascular diseases, and reviewed the progress of the delivery of genes to cardiovascular system by UTMD.