Cardiovascular gene therapy

Cardiac gene delivery using ultrasound: State of the field

Over the past two decades, there has been tremendous and exciting progress toward extending the use of medical ultrasound beyond a traditional imaging tool. Ultrasound contrast agents, typically used for improved visualization of blood flow, have been explored as novel non-viral gene delivery vectors for cardiovascular therapy. Given this adaptation to ultrasound contrast-enhancing agents, this presents as an image-guided and site-specific gene delivery technique with potential for multi-gene and repeatable delivery protocols-overcoming some of the limitations of alternative gene therapy approaches. In this review, we provide an overview of the studies to date that employ this technique toward cardiac gene therapy using cardiovascular disease animal models and summarize their key findings.

Dental pulp regeneration strategies: A review of status quo and recent advances

Microorganisms, physical factors such as temperature or mechanical injury, and chemical factors such as free monomers from composite resin are the main causes of dental pulp diseases. Current clinical treatment methods for pulp diseases include the root canal therapy, vital pulp therapy and regenerative endodontic therapy. Regenerative endodontic therapy serves the purpose of inducing the regeneration of new functional pulp tissues through autologous revascularization or pulp tissue engineering. This article first discusses the current clinical methods and reviews strategies as well as the research outcomes regarding the pulp regeneration. Then the in vivo models, the prospects and challenges for regenerative endodontic therapy were further discussed.

Nanotechnology: The Future for Diagnostic and Therapeutic Intervention in Cardiovascular Diseases is Here

With advances in technology and medicine over the last 3 decades, cardiovascular medicine has evolved tremendously. Nanotechnology provides a promising future in personalized precision medicine. In this review, we delve into the current and prospective applications of nanotechnology and nanoparticles in cardiology. Nanotechnology has allowed for point-of-care testing such as high-sensitivity troponins, as well as more precise cardiac imaging. This review is focused on 3 diseases within cardiology: coronary artery disease, heart failure, and valvular heart disease. The use of nanoparticles in coronary stents has shown success in preventing in-stent thrombosis, as well as using nanosized drug delivery medications to prevent neointimal proliferation in a way that spares systemic toxicity. In addition, by using nanoparticles as drug delivery systems, nanotechnology can be utilized in the delivery of goal-directed medical therapy in heart failure patients. It has also been shown to improve cell therapy in this patient population by helping in cell retention of grafts. Finally, the use of nanoparticles in the manufacturing of bioprosthetic valves provides a promising future for the longevity and success of cardiac valve repair and replacement.

Navigating the landscape: Prospects and hurdles in targeting vascular smooth muscle cells for atherosclerosis diagnosis and therapy

Vascular smooth muscle cells (VSMCs) have emerged as pivotal contributors throughout all phases of atherosclerotic plaque development, effectively dispelling prior underestimations of their prevalence and significance. Recent lineage tracing studies have unveiled the clonal nature and remarkable adaptability inherent to VSMCs, thereby illuminating their intricate and multifaceted roles in the context of atherosclerosis. This comprehensive review provides an in-depth exploration of the intricate mechanisms and distinctive characteristics that define VSMCs across various physiological processes, firmly underscoring their paramount importance in shaping the course of atherosclerosis. Furthermore, this review offers a thorough examination of the significant strides made over the past two decades in advancing imaging techniques and therapeutic strategies with a precise focus on targeting VSMCs within atherosclerotic plaques, notably spotlighting meticulously engineered nanoparticles as a promising avenue. We envision the potential of VSMC-targeted nanoparticles, thoughtfully loaded with medications or combination therapies, to effectively mitigate pro-atherogenic VSMC processes. These advancements are poised to contribute significantly to the pivotal objective of modulating VSMC phenotypes and enhancing plaque stability. Moreover, our paper also delves into recent breakthroughs in VSMC-targeted imaging technologies, showcasing their remarkable precision in locating microcalcifications, dynamically monitoring plaque fibrous cap integrity, and assessing the therapeutic efficacy of medical interventions. Lastly, we conscientiously explore the opportunities and challenges inherent in this innovative approach, providing a holistic perspective on the potential of VSMC-targeted strategies in the evolving landscape of atherosclerosis research and treatment.

Nanotechnology-based non-viral vectors for gene delivery in cardiovascular diseases

Gene therapy is a technique that rectifies defective or abnormal genes by introducing exogenous genes into target cells to cure the disease. Although gene therapy has gained some accomplishment for the diagnosis and therapy of inherited or acquired cardiovascular diseases, how to efficiently and specifically deliver targeted genes to the lesion sites without being cleared by the blood system remains challenging. Based on nanotechnology development, the non-viral vectors provide a promising strategy for overcoming the difficulties in gene therapy. At present, according to the physicochemical properties, nanotechnology-based non-viral vectors include polymers, liposomes, lipid nanoparticles, and inorganic nanoparticles. Non-viral vectors have an advantage in safety, efficiency, and easy production, possessing potential clinical application value when compared with viral vectors. Therefore, we summarized recent research progress of gene therapy for cardiovascular diseases based on commonly used non-viral vectors, hopefully providing guidance and orientation for future relevant research.

Dicationic amphiphiles bearing an amino acid head group with a long-chain hydrophobic tail for in vitro gene delivery applications

C14-P, C14-M, and C14-S lipids formed lipoplexes using pDNA. The lipoplex cellular uptake into the cells resulted in the release of nucleic acids. C14-P lipid showed superior eGFP transfection in non-cancer cell line and more apoptosis cell death in cancer cell line.

Gene therapy for ischaemic heart disease and heart failure

Gene therapy has been expected to become a novel treatment method since the structure of DNA was discovered in 1953. The morbidity from cardiovascular diseases remains remarkable despite the improvement of percutaneous interventions and pharmacological treatment, underlining the need for novel therapeutics. Gene therapy-mediated therapeutic angiogenesis could help those who have not gained sufficient symptom relief with traditional treatment methods. Especially patients with severe coronary artery disease and heart failure could benefit from gene therapy. Some clinical trials have reported improved myocardial perfusion and symptom relief in CAD patients, but few trials have come up with disappointing negative results. Translating preclinical success into clinical applications has encountered difficulties in successful transduction, study design, endpoint selection, and patient selection and recruitment. However, promising new methods for transducing the cells, such as retrograde delivery and cardiac-specific AAV vectors, hold great promise for myocardial gene therapy. This review introduces gene therapy for ischaemic heart disease and heart failure and discusses the current status and future developments in this field.

Therapeutic angiogenesis in coronary artery disease: a review of mechanisms and current approaches

INTRODUCTION

Despite tremendous advances, the shortcomings of current therapies for coronary disease are evidenced by the fact that it remains the leading cause of death in many parts of the world. There is hence a drive to develop novel therapies to tackle this disease. Therapeutic approaches to coronary angiogenesis have long been an area of interest in lieu of its incredible, albeit unrealized potential.

AREAS COVERED

This paper offers an overview of mechanisms of native angiogenesis and a description of angiogenic growth factors. It progresses to outline the advances in gene and stem cell therapy and provides a brief description of other investigational approaches to promote angiogenesis. Finally, the hurdles and limitations unique to this particular area of study are discussed.

EXPERT OPINION

An effective, sustained, and safe therapeutic option for angiogenesis truly could be the paradigm shift for cardiovascular medicine. Unfortunately, clinically meaningful therapeutic options remain elusive because promising animal studies have not been replicated in human trials. The sheer complexity of this process means that numerous major hurdles remain before therapeutic angiogenesis truly makes its way from the bench to the bedside.

Application of Cell, Tissue, and Biomaterial Delivery in Cardiac Regenerative Therapy

Cardiovascular diseases (CVD) are the leading cause of death around the world, being responsible for 31.8% of all deaths in 2017 (Roth, G. A. et al. The Lancet 2018, 392, 1736-1788). The leading cause of CVD is ischemic heart disease (IHD), which caused 8.1 million deaths in 2013 (Benjamin, E. J. et al. Circulation 2017, 135, e146-e603). IHD occurs when coronary arteries in the heart are narrowed or blocked, preventing the flow of oxygen and blood into the cardiac muscle, which could provoke acute myocardial infarction (AMI) and ultimately lead to heart failure and death. Cardiac regenerative therapy aims to repair and refunctionalize damaged heart tissue through the application of (1) intramyocardial cell delivery, (2) epicardial cardiac patch, and (3) acellular biomaterials. In this review, we aim to examine these current approaches and challenges in the cardiac regenerative therapy field.

Nanoparticle-Mediated Drug Delivery for the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are one of the foremost causes of high morbidity and mortality globally. Preventive, diagnostic, and treatment measures available for CVDs are not very useful, which demands promising alternative methods. Nanoscience and nanotechnology open a new window in the area of CVDs with an opportunity to achieve effective treatment, better prognosis, and less adverse effects on non-target tissues. The application of nanoparticles and nanocarriers in the area of cardiology has gathered much attention due to the properties such as passive and active targeting to the cardiac tissues, improved target specificity, and sensitivity. It has reported that more than 50% of CVDs can be treated effectively through the use of nanotechnology. The main goal of this review is to explore the recent advancements in nanoparticle-based cardiovascular drug carriers. This review also summarizes the difficulties associated with the conventional treatment modalities in comparison to the nanomedicine for CVDs.

Endothelium-Mimicking Multifunctional Coating Modified Cardiovascular Stents via a Stepwise Metal-Catechol-(Amine) Surface Engineering Strategy

Stenting is currently the major therapeutic treatment for cardiovascular diseases. However, the nonbiogenic metal stents are inclined to trigger a cascade of cellular and molecular events including inflammatory response, thrombogenic reactions, smooth muscle cell hyperproliferation accompanied by the delayed arterial healing, and poor reendothelialization, thus leading to restenosis along with late stent thrombosis. To address prevalence critical problems, we present an endothelium-mimicking coating capable of rapid regeneration of a competently functioning new endothelial layer on stents through a stepwise metal (copper)-catechol-(amine) (MCA) surface chemistry strategy, leading to combinatorial endothelium-like functions with glutathione peroxidase-like catalytic activity and surface heparinization. Apart from the stable nitric oxide (NO) generating rate at the physiological level (2.2 × 10^-10 mol/cm²/min lasting for 60 days), this proposed strategy could also generate abundant amine groups for allowing a high heparin conjugation efficacy up to ∼1 μg/cm², which is considerably higher than most of the conventional heparinized surfaces. The resultant coating could create an ideal microenvironment for bringing in enhanced anti-thrombogenicity, anti-inflammation, anti-proliferation of smooth muscle cells, re-endothelialization by regulating relevant gene expressions, hence preventing restenosis in vivo. We envision that the stepwise MCA coating strategy would facilitate the surface endothelium-mimicking engineering of vascular stents and be therefore helpful in the clinic to reduce complications associated with stenosis.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Gene Therapy: An Outstanding Technique For Diseases

Nearly three decades ago, the first clinical trial based on gene therapy revolutionized the scientific field by demonstrating that it was possible to genetically modify harmful or defective cells and therapeutically improve patient conditions. Since then, this technique has been implemented for the study and treatment of different diseases, many of them fatal, with the hope of achieving a "cure". Several genetic editing tools have been developed and continue to be studied to improve the effectiveness of gene therapy, in addition to a more exhaustive analysis for choosing the type of vector, which is the main cause of adverse effects. In this review, we present characteristics of the gene therapy mechanism along with the types of vectors that are used in this procedure, followed by the most important applications in the medical field and briefly we describe some limitations and prospects to study in the future.

Cell mimetic liposomal nanocarriers for tailored delivery of vascular therapeutics

Liposomal delivery systems (LDSs) have been at the forefront of medicinal nanotechnology for over three decades. Increasing LDS association to target cells and cargo delivery is crucial to bolstering overall nanodrug efficacy. Our laboratory aims to develop LDSs for molecular therapeutics aimed at vascular pathology. We have previously established a liposome platform that is an effective delivery system for RNA interference in vascular cell types by using polyethylene glycol (PEG) decorated liposomes bearing an octa-arginine (R8) cell penetrating peptide (CPP). Further tailoring liposome membranes to mimic vascular cell membrane lipid constituents may be a promising strategy for increasing cargo delivery. Here we aimed to develop liposomal formulations that could make use of diacylglycerol (DAG) and phosphatidylserine (PS), naturally occurring lipid species that are known to influence vascular cell function, as a facile and efficient means to increase nanodrug efficacy without compromising clinical viability. We investigated the ability of DAG and PS to amplify the cellular uptake of our previously established LDS platform loaded with small interfering ribonucleic acid (siRNA) cargo. Cellular fluorescence microscopy experiments were performed in conjunction with quantitative cell association assays and cytotoxicity assays to analyze the effect of DAG/PS on the differential delivery of fluorescently-tagged liposomes to vascular smooth muscle cells (VSMCs) and vascular endothelial cells (VECs) and on liposomal-mediated toxicity. In these studies, significant, dose-dependent increases in association to target cells were observed, as well as cell-type specific effects on cell viability. The stability and encapsulation-efficiency of the DAG/PS-modified LDSs were analyzed by standard nanoparticle characterization methods, and siRNA transfection efficacy was quantified to gauge delivery potential as a function of DAG/PS modification. Our results suggest that the signaling lipids tested here imbue our LDS architectures with increased therapeutic potential, without compromising stability, encapsulation efficiency, or biocompatibility, thus presenting a natural strategy to increase nanodrug efficacy and specificity.

Functionalized MoS2 Nanosheets as Multi-Gene Delivery Vehicles for In Vivo Pancreatic Cancer Therapy

Transition metal dichalcogenides (TMDCs) are categorized as novel two-dimensional (2D) nanomaterials with unique physical and chemical properties, bearing varied applications in medical and materials sciences. However, only a few works report the application of TMDCs for gene therapy in cancer treatment. Here, we engineer a multi-gene delivery system based on functionalized monolayer MoS2, which can co-deliver HDAC1 and KRAS small interfering RNAs (siRNAs) to Panc-1 cancer cells for combinational cancer therapy. The synergistic effect of gene silencing therapy and NIR phototherapy is demonstrated by inhibition of both genes, in vitro cell growth rate, and in vivo tumor volume growth rate, exemplifying pre-eminent anticancer efficacy. This anti-tumor effect is a result of the photothermal effect of MoS2 induced by NIR excitation and inactivation of HDAC1 and KRAS genes, which consequently bring about apoptosis, inhibit migration, and induce cell cycle arrest in the treated Panc-1 cells. Moreover, good biocompatibility and reduced cytotoxicity of MoS2-based nanocarriers enable their metabolism within in vitro and in vivo mouse models over a prolonged duration without any evident ill-effects. In summary, we demonstrate the promising potential of low-toxicity, functionalized MoS2 nanocarriers as a biocompatible gene delivery system for in vivo pancreatic adenocarcinoma therapy.

Chimeric Adeno-Associated Virus-Mediated Cardiovascular Reprogramming for Ischemic Heart Disease

Here, we demonstrated chimeric adeno-associated virus (chimeric AAV), AAV-DJ-mediated cardiovascular reprogramming strategy to generate new cardiomyocytes and limit collagen deposition in cardiac fibroblasts by inducing synergism of chimeric AAV-expressing Gata4, Mef2c, Tbx5 (AAV-GMT)-mediated heart reprogramming and chimeric AAV-expressing thymosin β4 (AAV-Tβ4)-mediated heart regeneration. AAV-GMT promoted a gradual increase in expression of cardiac-specific genes, including Actc1, Gja1, Myh6, Ryr2, and cTnT, with a gradual decrease in expression of a fibrosis-specific gene, procollagen type I and here AAV-Tβ4 help to induce GMT expression, providing a chimeric AAV-mediated therapeutic cell reprogramming strategy for ischemic heart diseases.

Correlation between increasing tissue ischemia and circulating levels of angiogenic growth factors in peripheral artery disease

INTRODUCTION

The aim of the present study was to assess the circulating levels of vascular endothelial growth factor (VEGF) and other suggested therapeutic growth factors with the degree of ischemia in patients with different clinical manifestations of peripheral arterial disease (PAD) according to the Rutherford grades.

METHODS

The study cohort consists of 226 consecutive patients admitted to a Department of Vascular Surgery for elective invasive procedures. PAD patients were grouped according to the Rutherford grades after a clinical assessment. Ankle-brachial pressure indices (ABI) and absolute toe pressure (TP) values were measured. Serum levels of circulating VEGF, hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), and platelet derived growth factor (PDGF) were measured from serum and analysed against Rutherford grades and peripheral hemodynamic measurements.

RESULTS

The levels of VEGF (P = 0.009) and HGF (P < 0.001) increased significantly as the ischaemic burden became more severe according to the Rutherford grades. PDGF behaved in opposite manner and declined along increasing Rutherford grades (P = 0.004). A significant, inverse correlations between Rutherford grades was detected as follows; VEGF (Pearson's correlation = 0.183, P = 0.004), HGF (Pearson's correlation = 0.253, P < 0.001), bFGF (Pearson's correlation = 0.169, P = 0.008) and PDGF (Pearson's correlation = 0.296, P < 0.001). In addition, VEGF had a clear direct negative correlation with ABI (Pearson's correlation -0.19, P = 0.009) and TP (Pearson's correlation -0.20, P = 0.005) measurements.

CONCLUSIONS

Our present observations show that the circulating levels of VEGF and other suggested therapeutic growth factors are significantly increased along with increasing ischemia. These findings present a new perspective to anticipated positive effects of gene therapies utilizing VEGF, HGF, and bFGF, because the levels of these growth factors are endogenously high in end-stage PAD.

Physical Chemical and Biomolecular Methods for the Optimization of Cationic Lipid-Based Lipoplexes In Vitro for the Gene Therapy Applications

Preparation and application protocols play a very important role while optimizing the cationic lipid-based lipoplexes in vitro. These protocols serve as the basis for the betterment of the lipoplexes with regard to their successful application in animals and eventually human subjects. Starting from the chemical structures of used cationic lipids (CLs), optimization of the additive inclusions, methods of nanoparticle (lipoplex) formation, presence of blood serum, time intervals of lipoplex incubation, and type of efficiency read-outs in various conditions play important roles in reaching insightful conclusions. Such steps of summarizing protocols and requirements of the pertinent events focus on getting improved lipoplexes for achieving optimal effects in terms of post transfection gene and protein expression. The progression of optimization and efficiency evaluation lead to predictable structure-method-activity relationship with involvement of various feedback principles including physical chemical and biomolecular evaluations before and after the use of lipoplexes in biological systems. This chapter discusses some of the focused strategies for the establishment of lipoplexes for a better post transfection activity with reduced risk of failure.

Improving the efficacy of liposome-mediated vascular gene therapy via lipid surface modifications

BACKGROUND

We have previously defined mechanisms of intimal hyperplasia that could be targets for molecular therapeutics aimed at vascular pathology. However, biocompatible nanocarriers are needed for effective delivery. Cationic liposomes (CLPs) have been demonstrated as effective nanocarriers in vitro. However, in vivo success has been hampered by cytotoxicity. Recently, neutral PEGylated liposomes (PLPs) have been modified with cell-penetrating peptides (CPPs) to enhance cellular uptake. We aim to establish CPP-modified neutral liposomes as viable molecular nanocarriers in vascular smooth muscle cells.

METHODS

CLPs, PLPs, and CPP-modified PLPs (R8-PLPs) were assembled with short interfering RNA (siRNA) via ethanol injection. Characterization studies determined liposomal morphology, size, and charge. siRNA encapsulation efficiency was measured via RiboGreen assay. Vascular smooth muscle cells were exposed to equal lipid/siRNA across all groups. Rhodamine-labeled liposomes were used to quantify cell association via fluorometry, live/dead dual stain was used to measure cytotoxicity, and gene silencing was measured by quantitative polymerase chain reaction.

RESULTS

R8-PLPs exhibited increased encapsulation efficiency equivalent to CLPs. PLPs and R8-PLP-5 mol% and R8-PLP-10 mol% had no cytotoxic effect. CLPs demonstrated significant cytotoxicity. R8-PLP-5 mol% and R8-PLP-10 mol% exhibited increased cell association versus PLPs. R8-PLP-10 mol% resulted in significant gene silencing, in a manner dependent on lipid-to-siRNA load capacity.

CONCLUSIONS

The negligible cytotoxicity and enhanced cellular association and gene silencing capacity exhibited by R8-PLPs reveal this class of liposomes as a candidate for future applications. Further modifications for optimizing R8-PLPs are still warranted to improve efficacy, and in vivo studies are needed for translational development. However, this could prove to be an optimal nanocarrier for vascular gene therapeutics.

ERK1/2 pathway regulates coxsackie and adenovirus receptor expression in mouse cardiac stem cells

Cardiac stem cells (CSCs) are the most promising and effective candidates for the therapy of cardiac regenerative diseases; however, they have marked limitations. For instance, the implantation of CSCs is hampered by factors such as their sustainability and long-term durability. Gene modification appears to be the most effective method of optimizing CSCs and gene therapy trials have demonstrated that efficient gene transfer is key to achieving therapeutic efficacy. However, the transduction ability of adenovirus (Ad) is limited. Previous studies have reported that low expression of coxsackie and adenovirus receptor (CAR) in target cells decreases the transduction efficiency. A promising method for improving Ad-mediated gene transfer is to increase CAR expression in target cells. The present study investigated the effect of the Raf-mitogen-associated protein kinase (MAPK) kinase (MEK)-extracellular signal-associated protein kinase (ERK) signaling pathway on the expression of CAR on CSCs, as this pathway decreases cell-cell adhesion via cell surface molecules. The results demonstrated that interference with the Raf-MEK-ERK signaling pathway by knockdown of ERK1/2 upregulated the expression of CAR. The entry of the Ad into the cells was increased following inhibition of ERK1/2. Moreover, following knockdown of CAR, the entry of Ad into cells was decreased. However, knockdown of c-Jun N-terminal kinase and p38 as other components of the MAPK pathway did not affect CAR expression. Therefore, CAR expression in CSCs may be mediated via the Raf-MEK-ERK signaling pathway. Upregulation of CAR by knockdown of ERK1/2 may significantly improve Ad-mediated genetic modification of CSCs in the treatment of cardiovascular diseases.

SiRNA Delivery with PEGylated Graphene Oxide Nanosheets for Combined Photothermal and Genetherapy for Pancreatic Cancer

Since the successful exfoliation of graphene from graphite in 2004, graphene and graphene oxide (GO) have been considered the most promising two-dimensional (2D) nanomaterials with distinguished physical and chemical characteristics and have attracted great attention in many different fields. Graphene oxide is well-known for its distinct physiochemical properties and shows only minimal cytotoxicity compared to carbon nanotubes. Until now, only limited efforts have been invested in utilizing GO for gene therapy in pancreatic cancer treatments. In this study, we utilized multi-functionalized monolayer GO as a gene delivery system to efficiently co-deliver HDAC1 and K-Ras siRNAs (small interfering RNAs targeting the HDAC1 gene and the G12C mutant K-Ras gene, respectively) to specifically target pancreatic cancer cells MIA PaCa-2. The systematic mechanistic elucidation of the dual gene silencing effects indicated the inactivation of both the HDAC1 and the K-Ras gene, thereby causing apoptosis, proliferation inhibition and cell cycle arrest in treated MIA PaCa-2 cells. The synergistic combination of gene silencing and NIR light thermotherapy showed significant anticancer efficacy, inhibiting in vivo tumor volume growth by >80%. Furthermore, GO can be metabolized in the mouse model within a reasonable period of time without obvious side effects. Based on preliminary in vivo application, this study for the first time indicates the promising potential of functionalized GO as a vehicle for gene therapy delivery with low toxicity for the treatment of pancreatic adenocarcinoma.

Delivery of CD151 by Ultrasound Microbubbles in Rabbit Myocardial Infarction

OBJECTIVES

We aimed to evaluate whether ultrasound (US) and microbubble-mediated delivery of Cluster of Differentiation 151 (CD151) could enhance the therapeutic effects of CD151 on myocardial infarction (MI).

METHODS

A rabbit model of MI was established by a modified Fujita method. Then, 50 MI rabbits were randomly divided into 5 groups, including G1 (CD151 plasmid and physiological saline in the presence of US); G2 (CD151 and Sonovue in the presence of US); G3 (CD151 and Sonovue in the absence of US); G4 (Sonovue in the absence of US), and a control group (physiological saline in the absence of US). After 14 days of treatment, the expression of CD151 was detected by Western blot. Besides, vessel density of peri-infarcted myocardium was measured by immunohistochemistry, and cardiac function was analyzed by echocardiography.

RESULTS

The rabbit model of MI was established successfully. CD151 injection increased the expression of CD151 and microvessel density in the myocardium of MI rabbits. Heart function was significantly improved by CD151, which exhibited increased left ventricular ejection fraction, left ventricular fractional shortening and a reduced Tei index. Besides, US Sonovue significantly increased the expression efficiency of CD151.

CONCLUSION

US microbubble was an effective vector for CD151 delivery. CD151 might be an effective therapeutic target for MI.

Therapeutic Angiogenesis Using Vascular Endothelial Growth Factor

Therapeutic angiogenesis using vascular endothelial growth factor can reduce tissue ischemia by simulating the natural process of angiogenesis. Vascular endothelial growth factor not only stimulates endothelial cells to proliferate and migrate, but also mobilizes endothelial progenitor cells and achieves vascular protection. Besides direct administration of angiogenic proteins, plasmids and viral vectors carrying angiogenic genes have been used. Animal experiments have shown promise with evidence of neovascularization and improved perfusion in the target myocardium. Initial phase I and II clinical trials results are encouraging and reflect the potential success of therapeutic angiogenesis as a clinical modality for the treatment of ischemic heart disease. This review discusses the role of vascular endothelial growth factor in therapeutic angiogenesis, along with the problems and considerations of this approach as a treatment strategy.

Epigenetherapy, a new concept

Small RNAs have been shown to regulate gene transcription by interacting with the promoter region and modifying the histone code. The exact mechanism of function is still unclear but the feasibility to activate or repress endogenous gene expression with small RNA molecules has already been demonstrated in vitro and in vivo. In traditional gene therapy non-mutated or otherwise useful genes are inserted into patient's cells to treat a disease. In epigenetherapy the action of small RNAs is utilized by delivering only the small RNAs to patient's cells where they then regulate gene expression by epigenetic mechanisms. This method could be widely useful not only for basic research but also for clinical applications of small RNAs.

Intramyocardial delivery of VEGF165 via a novel biodegradable hydrogel induces angiogenesis and improves cardiac function after rat myocardial infarction

Vascular endothelial growth factor (VEGF), an independent mitogen, has been reported to induce angiogenesis and thus attenuates the damage induced by myocardial infarction (MI). VEGF165 is the most abundant and predominant isoform of VEGF. This study investigates whether this effect could be strengthened by local intramyocardial injection of VEGF165 along with a novel biodegradable Dex-PCL-HEMA/PNIPAAm hydrogel and ascertains its possible mechanism of action. Rat models of myocardial infarction were induced by coronary artery ligation. Phosphate-buffered saline (PBS group), Dex-PCL-HEMA/PNIPAAm hydrogel (Gel group), phosphate-buffered saline containing VEGF165 (VP group), and hydrogel containing VEGF165 (VPG group) were injected into a peri-infarcted area of cardiac tissue immediately after myocardial infarction, respectively. The sham group was thoracic but without myocardial infarction. The injection of VEGF165 along with a hydrogel induced angiogenesis, reduced collagen content and MI area, inhibited cell apoptosis, increased the level of VEGF165 protein and the expression of flk-1 and flt-1, and improved cardiac function compared with the injection of either alone after MI in rats. The results suggest that injection of VEGF165 along with a hydrogel acquires more cardioprotective effects than either alone in rat with MI by sustained release of VEGF165, then may enhance the feedback between VEGF and its receptors flk-1 and flt-1.

Ultrasound-Targeted Microbubble Destruction Enhances Gene Expression of microRNA-21 in Swine Heart via Intracoronary Delivery

BACKGROUND

Ultrasound-targeted microbubble destruction (UTMD) has proved to be a promising method for gene delivery. However, the feasibility and efficacy of UTMD-mediated gene delivery to the heart of large animals remain unclear. The present study was to explore the probability of increasing the transfection of microRNA-21 (miR-21) in swine heart by UTMD, and to search for the most suitable transfection conditions.

METHODS

We first optimized ultrasound intensity for successful miR-21 delivery. After intravenous injection of miR-21/microbubble mixture (miR-21/MB), transthoracic ultrasound irradiation (US) was applied from the left anterior chest using different intensities (1, 2, and 3 W/cm(2)). Then the efficacy of UTMD-mediated miR-21 delivery into myocardium via intracoronary injection was explored. Solution of miR-21/MB was infused intravenously or intracoronarily with US over the heart. Swine undergoing phosphate-buffered saline (PBS) injection, miR-21/MB injection via ear vein or coronary artery without US served as the control. The dynamic changes of left ventricular ejection fraction (LVEF) and serum troponin I (cTnI) after UTMD were detected, then the left ventricular myocardium was harvested for hematoxylin and eosin (H&E) staining 4 days later; the expression levels of miR-21 and programmed cell death 4 (PDCD4) were detected by quantitative real time polymerase chain reaction (qRT-PCR) and Western blot, respectively.

RESULTS

Results showed that pulse ultrasound at an intensity of 2 W/cm(2) and a 50% duty ratio for 20 minutes, there was no increase in serum cTnI, no histological sign of myocardial damage, and no noted cardiac dysfunction with relatively higher miR-21 expression (P < 0.05). Compared to miR-21/MB alone, UTMD significantly increased gene expression in myocardium regardless of the delivery routes (P < 0.05). Interestingly, the transfection efficiency was found to be a little bit higher with intracoronary injection than that with intravenous injection, though the dose for intracoronary injection was half of the intravenous injection (P < 0.05).

CONCLUSION

Under suitable conditions, UTMD can efficiently enhance gene expression in swine heart regardless of the delivery routes. The intravenous injection might be superior to intracoronary injection with less invasiveness and lower requirement of the technique. And for those undergoing percutaneous coronary intervention, intracoronary injection seems to be another alternative.

Magnetic nanosphere-guided site-specific delivery of vascular endothelial growth factor gene attenuates restenosis in rabbit balloon-injured artery

OBJECTIVE

New and efficient strategies to protect endothelium or to enhance endothelial regrowth are important for treatment of restenosis after percutaneous transluminal angioplasty. Magnetic DNA microspheres are used to accelerate vascular endothelial growth factor (VEGF) re-endothelialization and to attenuate intimal hyperplasia in balloon-injured artery. This study aimed to assess DNA-gelatin magnetic nanospheres containing VEGF expression plasmids in vascular restenosis attenuation.

METHODS

Ninety-six rabbits underwent balloon injury and were randomly divided for gene transfer with naked VEGF plasmids (NAK group), magnetic VEGF microspheres (MIC group), and LacZ (CON group: naked LacZ plasmid and LacZ nanosphere subgroups). Serum and tissue VEGF levels were measured. Also, the ratios of intima area to media area were determined to assess neointima formation.

RESULTS

Microsphere gene delivery through the artery by a magnet resulted in VEGF overexpression in transfected arterial segments. Tissue VEGF integral optical densities were significantly increased in MIC rabbits compared with NAK animals. Serum VEGF was below detection in all animals. X-Gal staining showed higher transfection efficiency in the CON group. The impact of neointimal thickening was evaluated by light microscopy as the ratio of intima area to media area in cross sections. Significant differences in the ratio of intima area to media area were obtained between the NAK group (0.12 ± 0.02, 0.41 ± 0.03, 0.61 ± 0.05, and 0.72 ± 0.04 at 1, 2, 3, and 4 weeks, respectively) and the MIC group (0.06 ± 0.03, 0.20 ± 0.05, 0.25 ± 0.04, and 0.26 ± 0.03 at 1, 2, 3, and 4 weeks, respectively) at 2, 3, and 4 weeks (P < .05).

CONCLUSIONS

Intra-arterial VEGF gene delivery by magnetic microspheres significantly increased DNA stability, transfection efficiency, and targeting specificity, resulting in exogenous VEGF overexpression and attenuated intimal hyperplasia in balloon-injured artery.

Bioreducible polymers for therapeutic gene delivery

Most currently available cationic polymers have significant acute toxicity concerns such as cellular toxicity, aggregation of erythrocytes, and entrapment in the lung capillary bed, largely due to their poor biocompatibility and non-degradability under physiological conditions. To develop more intelligent polymers, disulfide bonds are introduced in the design of biodegradable polymers. Herein, the sustained innovations of biomimetic nano-sized constructs with bioreducible poly(disulfide amine)s demonstrate a viable clinical tool for the treatment of cardiovascular disease, anemia, diabetes, and cancer.

Neuropilin 1 expression in human aortas, coronaries and the main bypass grafts

OBJECTIVES

Development of intimal hyperplasia (IH) is the main pathology underlying graft failure following coronary artery bypass graft surgeries for ischaemic heart diseases, especially for great saphenous vein grafts which have a lower patency rate than internal mammary arteries. Neuropilin 1 (NRP1), which is a co-receptor for vascular endothelial growth factor found in vascular endothelial and smooth muscle cells, affects the development of IH. We examined the difference in NRP1 expression and distribution in human coronaries, aortas, mammary arteries and saphenous veins to detect a possible relation to their susceptibility to IH.

METHODS

Ninety-five human vascular segments obtained from 40 patients were used for the comparison of NRP1 expression between different groups of blood vessels by western blot and real-time PCR. Additionally, staining scores were generated by computerized analysis of the microscopic images obtained after immunofluorescence and immunohistochemical staining to compare NRP1 expression patterns in endothelium, smooth muscles and adventitia in each vessel type.

RESULTS

NRP1 expression in the aorta (2.03 ± 1.44) was more than twice as high as mammary artery expression (0.85 ± 0.75; n = 16, P = 0.0004); NRP1 of the latter (0.99 ± 0.91) was more than 30% greater than that of the corresponding saphenous vein (0.73 ± 0.69; n = 20, P = 0.0085). In adventitia, NRP1 receptor staining of the saphenous vein was higher (22.96 ± 8.73) than in the mammary artery (15.83 ± 7.13; n = 7, P = 0.049). Variations in NRP1 protein levels were accompanied by parallel variations in its mRNA levels (n = 15, P = 0.34).

CONCLUSIONS

Autologous saphenous vein grafts, unlike internal mammary artery grafts, have lower NRP1 expression and abundant adventitial distribution of NRP1 within their walls; this may correlate with higher susceptibility to IH development.

Therapeutic angiogenesis for myocardial ischemia

Therapeutic angiogenesis offers promise as a novel treatment for ischemic heart disease, particularly for patients who are not candidates for current methods of revascularization. The goal of treatment is both relief of symptoms of coronary artery disease and improvement of cardiac function by increasing perfusion to the ischemic region. Protein-based therapy with cytokines including vascular endothelial growth factor and fibroblast growth factor demonstrated functionally significant angiogenesis in several animal models. However, clinical trials have yielded largely disappointing results. The attenuated angiogenic response seen in clinical trials of patients with coronary artery disease may be due to multiple factors including endothelial dysfunction, particularly in the context of advanced atherosclerotic disease and associated comorbid conditions, regimens of single agents, as well as inefficiencies of current delivery methods. Gene therapy has several advantages over protein therapy and recent advances in gene transfer techniques have improved the feasibility of this approach. The safety and tolerability of therapeutic angiogenesis by gene transfer has been demonstrated in phase I clinical trials. The utility of therapeutic angiogenesis by gene transfer as a treatment option for ischemic cardiovascular disease will be determined by adequately powered, randomized, placebo-controlled Phase II and III clinical trials. Cell-based therapies offer yet another approach to therapeutic angiogenesis. Although it is a promising therapeutic strategy, additional preclinical studies are warranted to determine the optimal cell type to be administered, as well as the optimal delivery method. It is likely the optimal treatment will involve multiple agents as angiogenesis is a complex process involving a large cascade of cytokines, as well as cells and extracellular matrix, and administration of a single factor may be insufficient. The promise of therapeutic angiogenesis as a novel treatment for no-option patients should be approached with cautious optimism as the field progresses.

Inhibition of neointimal hyperplasia in a rabbit vein graft model following non-viral transfection with human iNOS cDNA

Vein graft failure caused by neointimal hyperplasia (IH) after coronary artery bypass grafting with saphenous veins is a major clinical problem. The lack of safe and efficient vectors for vascular gene transfer has significantly hindered progress in this field. We have developed a Receptor-Targeted Nanocomplex (RTN) vector system for this purpose and assessed its therapeutic efficacy in a rabbit vein graft model of bypass grafting. Adventitial delivery of β-Galactosidase showed widespread transfection throughout the vein wall on day 7, estimated at about 10% of cells in the adventitia and media. Vein grafts were then transfected with a plasmid encoding inducible nitric oxide synthase (iNOS) and engrafted into the carotid artery. Fluorescent immunohistochemistry analysis of samples from rabbits killed at 7 days after surgery showed that mostly endothelial cells and macrophages were transfected. Morphometric analysis of vein graft samples from the 28-day groups showed approximately a 50% reduction of neointimal thickness and 64% reduction of neointimal area in the iNOS-treated group compared with the surgery control groups. This study demonstrates efficacy of iNOS gene delivery by the RTN formulation in reducing IH in the rabbit model of vein graft disease.

Homocysteine lowering interventions for peripheral arterial disease and bypass grafts

BACKGROUND

Elevated plasma levels of the amino acid homocysteine (hyperhomocysteinaemia) are associated with narrowing or blocking of the arteries (atherosclerosis). Treatment to lower homocysteine levels has been shown to be both effective and cheap in healthy volunteers. However, the impact of reducing homocysteine levels on the progression of atherosclerosis and patency of the vessels after treatment for atherosclerosis is still unknown and forms the basis for this review. This is the second update of a review first published in 2002.

OBJECTIVES

To assess the effects of plasma homocysteine lowering therapy on the clinical progression of disease in people with peripheral arterial disease (PAD) and hyperhomocysteinaemia including, as a subset, those who have undergone surgical or radiological intervention.

SEARCH METHODS

For this update, the Cochrane Peripheral Vascular Disease Group Trials Search Co-ordinator (TSC) searched the Specialised Register (last searched January 2013) and CENTRAL (2012, Issue 12). Trial databases were searched by the TSC (January 2013) for details of ongoing and unpublished studies. We also searched the reference lists of relevant articles.

SELECTION CRITERIA

Randomised trials in which participants with PAD and hyperhomocysteinaemia were allocated to either homocysteine lowering therapy or no treatment, including participants before and after surgical or radiological interventions.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted the data. Information on adverse events was collected from the trials.

MAIN RESULTS

Two randomised trials with a total of 161 participants were included in this review. The studies did not report on mortality and rate of limb loss. One randomised trial with a total of 133 participants showed that there was a significant improvement in ankle brachial index (ABI) in participants who received folic acid compared with placebo (mean difference (MD) 0.07, 95% confidence interval (CI) 0.04 to 0.11, P < 0.001) and in participants who received 5-methyltetrahydrofolate (5-MTHF) versus placebo (MD 0.05, 95% CI 0.01 to 0.10, P = 0.009). A second trial with a total of 18 participants showed that there was no difference (P non-significant) in ABI in participants who received a multivitamin B supplement (mean ± SEM: 0.7 ± 01) compared with placebo (mean ± SEM: 0.8 ± 0.1). No major events were reported.

AUTHORS' CONCLUSIONS

Currently, no recommendation can be made regarding the value of treatment of hyperhomocysteinaemia in peripheral arterial disease. Further, well constructed trials are urgently required.

Gene transfection in high serum levels: case studies with new cholesterol based cationic gemini lipids

Background

Six new cationic gemini lipids based on cholesterol possessing different positional combinations of hydroxyethyl (-CH₂CH₂OH) and oligo-oxyethylene -(CH₂CH₂O)_n- moieties were synthesized. For comparison the corresponding monomeric lipid was also prepared. Each new cationic lipid was found to form stable, clear suspensions in aqueous media.

Methodology/Principal Findings

To understand the nature of the individual lipid aggregates, we have studied the aggregation properties using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and X-ray diffraction (XRD). We studied the lipid/DNA complex (lipoplex) formation and the release of the DNA from such lipoplexes using ethidium bromide. These gemini lipids in presence of a helper lipid, 1, 2-dioleoyl phophatidyl ethanol amine (DOPE) showed significant enhancements in the gene transfection compared to several commercially available transfection agents. Cholesterol based gemini having -CH₂-CH₂-OH groups at the head and one oxyethylene spacer was found to be the most effective lipid, which showed transfection activity even in presence of high serum levels (50%) greater than Effectene, one of the potent commercially available transfecting agents. Most of these geminis protected plasmid DNA remarkably against DNase I in serum, although the degree of stability was found to vary with their structural features.

Conclusions/Significance

-OH groups present on the cationic headgroups in combination with oxyethylene linkers on cholesterol based geminis, gave an optimized combination of new genera of gemini lipids possessing high transfection efficiency even in presence of very high percentage of serum. This property makes them preferential transfection reagents for possible in vivo studies.

The changing face of vascular interventional radiology: the future role of pharmacotherapies and molecular imaging

Interventional radiology has had to evolve constantly because there is the ever-present competition and threat from other specialties within medicine, surgery, and research. The development of new technologies, techniques, and therapies is vital to broaden the horizon of interventional radiology and to ensure its continued success in the future. In part, this change will be due to improved chronic disease prevention altering what we treat and in whom. The most important of these strategies are the therapeutic use of statins, Beta-blockers, angiotensin-converting enzyme inhibitors, and substances that interfere with mast cell degeneration. Molecular imaging and therapeutic strategies will move away from conventional techniques and nano and microparticle molecular technology, tissue factor imaging, gene therapy, endothelial progenitor cells, and photodynamic therapy will become an important part of interventional radiology of the future. This review looks at these new and exciting technologies.

Mechanistic, technical, and clinical perspectives in therapeutic stimulation of coronary collateral development by angiogenic growth factors

Stimulation of collateral vessel development in the heart by angiogenic growth factor therapy has been tested in animals and humans for almost two decades. Discordance between the outcome of preclinical studies and clinical trials pointed to the difficulties of translation from animal models to patients. Lessons learned in this process identified specific mechanistic, technical, and clinical hurdles, which need to be overcome. This review summarizes current understanding of the mechanisms leading to the establishment of a functional coronary collateral network and the biological processes growth factor therapies should stimulate even under conditions of impaired natural adaptive vascular response. Vector delivery methods are recommended to maximize angiogenic gene therapy efficiency and reduce side effects. Optimization of clinical trial design should include the choice of clinical end points which provide mechanistic proof-of-concept and also reflect clinical benefits (e.g., surrogates to assess increased collateral flow reserve, such as myocardial perfusion imaging). Guidelines are proposed to select patients who may respond to the therapy with high(er) probability. Both short and longer term strategies are outlined which may help to make therapeutic angiogenesis (TA) work in the future.

Drug delivery systems for the treatment of ischemic stroke

Stroke is the third leading cause of death in the United States. Reduced cerebral blood flow causes acute damage to the brain due to excitotoxicity, reactive oxygen species (ROS), and ischemia. Currently, the main treatment for stroke is to revive the blood flow by using thrombolytic agents. Reviving blood flow also causes ischemia-reperfusion (I/R) damage. I/R damage results from inflammation and apoptosis and can persist for days to weeks, increasing the infarct size. Drugs can be applied to stroke to intervene in the sub-acute and chronic phases. Chemical, peptide, and genetic therapies have been evaluated to reduce delayed damage to the brain. These drugs have different characteristics, requiring that delivery carriers be developed based on these characteristics. The delivery route is another important factor affecting the efficiency of drug delivery. Various delivery routes have been developed, such as intravenous injection, intranasal administration, and local direct injection to overcome the blood-brain-barrier (BBB). In this review, the delivery carriers and delivery routes for peptide and gene therapies are discussed and examples are provided. Combined with new drugs, drug delivery systems will eventually provide useful treatments for ischemic stroke.

Overexpression of endothelial nitric oxide synthase improves endothelium-dependent vasodilation in arteries infused with helper-dependent adenovirus

Adenoviral vectors (Ad) are useful tools for in vivo gene transfer into endothelial cells. However, endothelium-dependent vasodilation is impaired after Ad infusion, and this impairment is not prevented by use of advanced-generation "helper-dependent" (HD) Ad that lack all viral genes. We hypothesized that endothelium-dependent vasodilation could be improved in Ad-infused arteries by overexpression of endothelial nitric oxide synthase (eNOS). We tested this hypothesis in hyperlipidemic, atherosclerosis-prone rabbits because HDAd will likely be used for treating and preventing atherosclerosis. Moreover, the consequences of eNOS overexpression might differ in normal and atherosclerosis-prone arteries and could include atherogenic effects, as reported in transgenic mice. We cloned rabbit eNOS and constructed an HDAd that expresses it. HDAdeNOS increased NO production by cultured endothelial cells and increased arterial eNOS mRNA in vivo by ∼10-fold. Compared to arteries infused with a control HDAd, HDAdeNOS-infused arteries of hyperlipidemic rabbits had significantly improved endothelium-dependent vasodilation, and similar responses to phenylephrine and nitroprusside. Moreover, infusion of HDAdeNOS had local atheroprotective effects including large, significant decreases in intimal lipid accumulation and arterial tumor necrosis factor (TNF)-α expression (p≤0.04 for both). HDAdeNOS infusion yields a durable (≥2 weeks) increase in arterial eNOS expression, improves vasomotor function, and reduces artery wall inflammation and lipid accumulation. Addition of an eNOS expression cassette improves the performance of HDAd, has no harmful effects, and may reduce atherosclerotic lesion growth.

Cyclen-based cationic lipids for highly efficient gene delivery towards tumor cells

BACKGROUND

Gene therapy has tremendous potential for both inherited and acquired diseases. However, delivery problems limited their clinical application, and new gene delivery vehicles with low cytotoxicity and high transfection efficiency are greatly required.

METHODS

In this report, we designed and synthesized three amphiphilic molecules (L1-L3) with the structures involving 1, 4, 7, 10-tetraazacyclododecane (cyclen), imidazolium and a hydrophobic dodecyl chain. Their interactions with plasmid DNA were studied via electrophoretic gel retardation assays, fluorescent quenching experiments, dynamic light scattering and transmission electron microscopy. The in vitro gene transfection assay and cytotoxicity assay were conducted in four cell lines.

RESULTS

Results indicated that L1 and L3-formed liposomes could effectively bind to DNA to form well-shaped nanoparticles. Combining with neutral lipid DOPE, L3 was found with high efficiency in gene transfer in three tumor cell lines including A549, HepG2 and H460. The optimized gene transfection efficacy of L3 was nearly 5.5 times more efficient than that of the popular commercially available gene delivery agent Lipofectamine 2000™ in human lung carcinoma cells A549. In addition, since L1 and L3 had nearly no gene transfection performance in normal cells HEK293, these cationic lipids showed tumor cell-targeting property to a certain extent. No significant cytotoxicity was found for the lipoplexes formed by L1-L3, and their cytotoxicities were similar to or slightly lower than the lipoplexes prepared from Lipofectamine 2000™.

CONCLUSION

Novel cyclen-based cationic lipids for effective in vitro gene transfection were founded, and these studies here may extend the application areas of macrocyclic polyamines, especially for cyclen.