Cardiovascular gene therapy for myocardial infarction

An Intrinsically Magnetic Epicardial Patch for Rapid Vascular Reconstruction and Drug Delivery

Myocardial infarction (MI) is a major cause of mortality worldwide. The major limitation of regenerative therapy for MI is poor cardiac retention of therapeutics, which results from an inefficient vascular network and poor targeting ability. In this study, a two-layer intrinsically magnetic epicardial patch (MagPatch) prepared by 3D printing with biocompatible materials like poly (glycerol sebacate) (PGS) is designed, poly (ε-caprolactone) (PCL), and NdFeB. The two-layer structure ensured that the MagPatch multifariously utilized the magnetic force for rapid vascular reconstruction and targeted drug delivery. MagPatch accumulates superparamagnetic iron oxide (SPION)-labelled endothelial cells, instantly forming a ready-implanted organization, and rapidly reconstructs a vascular network anastomosed with the host. In addition, the prefabricated vascular network within the MagPatch allowed for the efficient accumulation of SPION-labelled therapeutics, amplifying the therapeutic effects of cardiac repair. This study defined an extendable therapeutic platform for vascularization-based targeted drug delivery that is expected to assist in the progress of regenerative therapies in clinical applications.

Efficient cardiac gene transfer and early-onset expression of a synthetic adeno-associated viral vector, Anc80L65, after intramyocardial administration

OBJECTIVE

Gene therapy is a promising approach in the treatment of cardiovascular diseases. Preclinical and clinical studies have demonstrated that adeno-associated viral vectors are the most attractive vehicles for gene transfer. However, preexisting immunity, delayed gene expression, and postinfection immune response limit the success of this technology. The aim of this study was to investigate the efficacy of the first synthetic adeno-associated viral lineage clone, Anc80L65, for cardiac gene therapy.

METHODS

By combining 2 different reporter approaches by fluorescence with green fluorescent protein and bioluminescence (Firefly luciferase), we compared transduction efficiency of Anc80L65 and adeno-associated virus, serotype 9 in neonatal rat cardiomyocytes ex vivo and rat hearts in vivo after intramyocardial and intracoronary administration.

RESULTS

In cardiomyocytes, Anc80L65 provided a green fluorescent protein expression of 28.9% (36.4 ± 3.34 cells/field) at 24 hours and approximately 100% on day 7. In contrast, adeno-associated virus, serotype 9 green fluorescent protein provided minimal green fluorescent protein expression of 5.64% at 24 hours and 11.8% on day 7. After intramyocardial injection, vector expression peaked on day 7 with Anc80L65; however, with adeno-associated virus, serotype 9 the peak expression was during week 6. Administration of Anc80L65 demonstrated significantly more efficient expression of reporter gene than after adeno-associated virus, serotype 9 at 6 weeks (6.81 ± 0.64 log10 gc/100 ng DNA vs 6.49 ± 0.28 log10 gc/100 ng DNA, P < .05). These results were consistent with the amount of genome copy per cell observed in the heart.

CONCLUSIONS

Anc80L65 vector allows fast and robust gene transduction compared with adeno-associated virus, serotype 9 vector in cardiac gene therapy. Anc80L65 did not adversely affect cardiac function and caused no inflammatory response or toxicity.

Cell-Based and Selected Cell-Free Therapies for Myocardial Infarction: How Do They Compare to the Current Treatment Options?

Because of cardiomyocyte death or dysfunction frequently caused by myocardial infarction (MI), heart failure is a leading cause of morbidity and mortality in modern society. Paradoxically, only limited and non-curative therapies for heart failure or MI are currently available. As a result, over the past two decades research has focused on developing cell-based approaches promoting the regeneration of infarcted tissue. Cell-based therapies for myocardial regeneration include powerful candidates, such as multipotent stem cells (mesenchymal stem cells (MSCs), bone-marrow-derived stem cells, endothelial progenitor cells, and hematopoietic stem cells) and induced pluripotent stem cells (iPSCs). These possess unique properties, such as potency to differentiate into desired cell types, proliferation capacity, and patient specificity. Preclinical and clinical studies have demonstrated modest improvement in the myocardial regeneration and reduced infarcted areas upon transplantation of pluripotent or multipotent stem cells. Another cell population that need to be considered as a potential source for cardiac regeneration are telocytes found in different organs, including the heart. Their therapeutic effect has been studied in various heart pathologies, such as MI, arrhythmias, or atrial amyloidosis. The most recent cell-free therapeutic tool relies on the cardioprotective effect of complex cargo carried by small membrane-bound vesicles—exosomes—released from stem cells via exocytosis. The MSC/iPSC-derived exosomes could be considered a novel exosome-based therapy for cardiovascular diseases thanks to their unique content. There are also other cell-free approaches, e.g., gene therapy, or acellular cardiac patches. Therefore, our review provides the most recent insights into the novel strategies for myocardial repair based on the regenerative potential of different cell types and cell-free approaches.

Signaling pathways and targeted therapy for myocardial infarction

Although the treatment of myocardial infarction (MI) has improved considerably, it is still a worldwide disease with high morbidity and high mortality. Whilst there is still a long way to go for discovering ideal treatments, therapeutic strategies committed to cardioprotection and cardiac repair following cardiac ischemia are emerging. Evidence of pathological characteristics in MI illustrates cell signaling pathways that participate in the survival, proliferation, apoptosis, autophagy of cardiomyocytes, endothelial cells, fibroblasts, monocytes, and stem cells. These signaling pathways include the key players in inflammation response, e.g., NLRP3/caspase-1 and TLR4/MyD88/NF-κB; the crucial mediators in oxidative stress and apoptosis, for instance, Notch, Hippo/YAP, RhoA/ROCK, Nrf2/HO-1, and Sonic hedgehog; the controller of myocardial fibrosis such as TGF-β/SMADs and Wnt/β-catenin; and the main regulator of angiogenesis, PI3K/Akt, MAPK, JAK/STAT, Sonic hedgehog, etc. Since signaling pathways play an important role in administering the process of MI, aiming at targeting these aberrant signaling pathways and improving the pathological manifestations in MI is indispensable and promising. Hence, drug therapy, gene therapy, protein therapy, cell therapy, and exosome therapy have been emerging and are known as novel therapies. In this review, we summarize the therapeutic strategies for MI by regulating these associated pathways, which contribute to inhibiting cardiomyocytes death, attenuating inflammation, enhancing angiogenesis, etc. so as to repair and re-functionalize damaged hearts.

Cardiac Targeted Adeno-Associated Virus Injection in Rats

Gene therapy is a promising approach in the treatment of cardiovascular diseases. The vectors available for cardiovascular gene therapy have significantly improved over time. Cardiac tropism is a primary characteristic of an ideal vector along with a long-term expression profile and a minimal risk of cellular immune response. Preclinical and clinical studies have demonstrated that adeno-associated viral (AAV) vectors are one of the most attractive vehicles for gene transfer. AAV has gained great popularity in the last years because of its biological properties and advantages over other viral vector systems. In this chapter we will describe methods for intracardiac delivery of AAV vector in rats.

Elabela gene therapy promotes angiogenesis after myocardial infarction

This study was aimed at investigating whether Elabela (ELA) gene therapy can promote angiogenesis in the treatment of myocardial infarction (MI). The fusion expression plasmid pAAV-3 × Flag/ELA-32 was successfully constructed using molecular cloning technique. The model of acute MI was established by ligating the left anterior descending coronary artery in mice. Adeno-associated virus serotype 9 (AAV9) was injected into the surrounding myocardium and tail vein immediately after the model was established. AAV was injected again from the tail vein one week later. Compared with the MI+PBS (control) group, the serum N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration, and the values of left ventricular end-diastolic diameter (LVDd) and left ventricular end-systolic diameter (LVDs) of the MI+AAV-ELA (gene therapy) group were significantly decreased, while the value of left ventricular ejection fraction was significantly increased at 2 and 4 weeks after operation. Compared with the control group, the expression of CD105 and vWF and the percentage of CD31- and Ki67-co-positive cells were significantly increased in the gene therapy group. Moreover, the expressions of apelin peptide jejunum (APJ) receptor, vascular endothelial growth factor (VEGF), VEGFR2, Jagged1 and Notch3 in the heart tissue around the infarction were up-regulated in mice with gene therapy. The results suggest that ELA activates VEFG/VEGFR2 and Jagged1/Notch3 pathways through APJ to promote angiogenesis after myocardial infarction. ELA gene therapy may be used in the treatment of ischaemic cardiomyopathy in future.

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.

Adeno-associated viral (AAV) vector-mediated therapeutics for diabetic cardiomyopathy - current and future perspectives

Diabetes increases the prevalence of heart failure by 6-8-fold, independent of other comorbidities such as hypertension and coronary artery disease, a phenomenon termed diabetic cardiomyopathy. Several key signalling pathways have been identified that drive the pathological changes associated with diabetes-induced heart failure. This has led to the development of multiple pharmacological agents that are currently available for clinical use. While fairly effective at delaying disease progression, these treatments do not reverse the cardiac damage associated with diabetes. One potential alternative avenue for targeting diabetes-induced heart failure is the use of adeno-associated viral vector (AAV) gene therapy, which has shown great versatility in a multitude of disease settings. AAV gene therapy has the potential to target specific cells or tissues, has a low host immune response and has the possibility to represent a lifelong cure, not possible with current conventional pharmacotherapies. In this review, we will assess the therapeutic potential of AAV gene therapy as a treatment for diabetic cardiomyopathy.

Recent Development in Therapeutic Cardiac Patches

For the past decades, heart diseases remain the leading cause of death worldwide. In the adult mammalian heart, damaged cardiomyocytes will be replaced by non-contractile fibrotic scar tissues due to the poor regenerative ability of heart, causing heart failure subsequently. The development of tissue engineering has launched a new medical innovation for heart regeneration. As one of the most outstanding technology, cardiac patches hold the potential to restore cardiac function clinically. Consisted of two components: therapeutic ingredients and substrate scaffolds, the fabrication of cardiac patches requires both advanced bioactive molecules and biomaterials. In this review, we will present the most state-of-the-art cardiac patches and analysis their compositional details. The therapeutic ingredients will be discussed from cell sources to bioactive molecules. In the meanwhile, the recent advances to obtain scaffold biomaterials will be highlighted, including synthetic and natural materials. Also, we have focused on the challenges and potential strategies to fabricate clinically applicable cardiac patches.

Angiogenesis after acute myocardial infarction

Acute myocardial infarction (MI) inflicts massive injury to the coronary microcirculation leading to vascular disintegration and capillary rarefication in the infarct region. Tissue repair after MI involves a robust angiogenic response that commences in the infarct border zone and extends into the necrotic infarct core. Technological advances in several areas have provided novel mechanistic understanding of postinfarction angiogenesis and how it may be targeted to improve heart function after MI. Cell lineage tracing studies indicate that new capillary structures arise by sprouting angiogenesis from pre-existing endothelial cells (ECs) in the infarct border zone with no meaningful contribution from non-EC sources. Single-cell RNA sequencing shows that ECs in infarcted hearts may be grouped into clusters with distinct gene expression signatures, likely reflecting functionally distinct cell populations. EC-specific multicolour lineage tracing reveals that EC subsets clonally expand after MI. Expanding EC clones may arise from tissue-resident ECs with stem cell characteristics that have been identified in multiple organs including the heart. Tissue repair after MI involves interactions among multiple cell types which occur, to a large extent, through secreted proteins and their cognate receptors. While we are only beginning to understand the full complexity of this intercellular communication, macrophage and fibroblast populations have emerged as major drivers of the angiogenic response after MI. Animal data support the view that the endogenous angiogenic response after MI can be boosted to reduce scarring and adverse left ventricular remodelling. The improved mechanistic understanding of infarct angiogenesis therefore creates multiple therapeutic opportunities. During preclinical development, all proangiogenic strategies should be tested in animal models that replicate both cardiovascular risk factor(s) and the pharmacotherapy typically prescribed to patients with acute MI. Considering that the majority of patients nowadays do well after MI, clinical translation will require careful selection of patients in need of proangiogenic therapies.

A Potent Branched-Tail Lipid Nanoparticle Enables Multiplexed mRNA Delivery and Gene Editing In Vivo

The clinical translation of messengerRNA (mRNA) drugs has been slowed by a shortage of delivery vehicles that potently and safely shuttle mRNA into target cells. Here, we describe the properties of a particularly potent branched-tail lipid nanoparticle that delivers mRNA to >80% of three major liver cell types. We characterize mRNA delivery spatially, temporally, and as a function of injection type. Following intravenous delivery, our lipid nanoparticle induced greater protein expression than two benchmark lipids, C12-200 and DLin-MC3-DMA, at an mRNA dose of 0.5 mg/kg. Lipid nanoparticles were sufficiently potent to codeliver three distinct mRNAs (firefly luciferase, mCherry, and erythropoietin) and, separately, Cas9 mRNA and single guide RNA (sgRNA) for proof-of-concept nonviral gene editing in mice. Furthermore, our branched-tail lipid nanoparticle was neither immunogenic nor toxic to the liver. Together, these results demonstrate the unique potential of this lipid material to improve the management of diseases rooted in liver dysfunction.

Anti-ageing gene therapy: Not so far away?

Improving healthspan is the main objective of anti-ageing research. Currently, innovative gene therapy-based approaches seem to be among the most promising for preventing and treating chronic polygenic pathologies, including age-related ones. The gene-based therapy allows to modulate the genome architecture using both direct (e.g., by gene editing) and indirect (e.g., by viral or non-viral vectors) approaches. Nevertheless, considering the extraordinary complexity of processes involved in ageing and ageing-related diseases, the effectiveness of these therapeutic options is often unsatisfactory and limited by their side-effects. Thus, clinical implementation of such applications is certainly a long-time process that will require many translation phases for addressing challenges. However, after overcoming these issues, their implementation in clinical practice may obviously provide new possibilities in anti-ageing medicine. Here, we review and discuss recent advances in this rapidly developing research field.

p27kip1 haploinsufficiency preserves myocardial function in the early stages of myocardial infarction via Atg5‑mediated autophagy flux restoration

Myocardial infarction (MI) is a leading cause of mortality in adults worldwide. Over the last two decades, gene therapy has been a hot topic in cardiology, and there has been a focus on cell cycle inhibitors and their protective effects on the myocardium post-MI. In our previous study, the haploinsufficiency of p27^kip1 (p27) was demonstrated to improve cardiac function in mice post-MI by promoting angiogenesis and myocardium protection through the secretion of growth factors. Autophagy is an adaptive response of cells to environmental changes, such as nutrient deprivation, ischemia and hypoxia. The appropriate regulation of autophagy may improve myocardial function by preventing apoptosis of cardiomyocytes. In this study, we used immunoassays, transmission electron microscopy and cardiac ultrasound to confirm that p27 haploinsufficiency prevents myocardial apoptosis by restoring autophagy protein 5-mediated autophagy flux in the early stages of MI. The present study provides a novel method for studying MI or ischemic heart disease therapy.

Myocardial infarction stabilization by cell-based expression of controlled Vascular Endothelial Growth Factor levels

Vascular Endothelial Growth Factor (VEGF) can induce normal or aberrant angiogenesis depending on the amount secreted in the microenvironment around each cell. Towards a possible clinical translation, we developed a Fluorescence Activated Cell Sorting (FACS)-based technique to rapidly purify transduced progenitors that homogeneously express a desired specific VEGF level from heterogeneous primary populations. Here, we sought to induce safe and functional angiogenesis in ischaemic myocardium by cell-based expression of controlled VEGF levels. Human adipose stromal cells (ASC) were transduced with retroviral vectors and FACS purified to generate two populations producing similar total VEGF doses, but with different distributions: one with cells homogeneously producing a specific VEGF level (SPEC), and one with cells heterogeneously producing widespread VEGF levels (ALL), but with an average similar to that of the SPEC population. A total of 70 nude rats underwent myocardial infarction by coronary artery ligation and 2 weeks later VEGF-expressing or control cells, or saline were injected at the infarction border. Four weeks later, ventricular ejection fraction was significantly worsened with all treatments except for SPEC cells. Further, only SPEC cells significantly increased the density of homogeneously normal and mature microvascular networks. This was accompanied by a positive remodelling effect, with significantly reduced fibrosis in the infarcted area. We conclude that controlled homogeneous VEGF delivery by FACS-purified transduced ASC is a promising strategy to achieve safe and functional angiogenesis in myocardial ischaemia.

An injectable conductive hydrogel encapsulating plasmid DNA-eNOs and ADSCs for treating myocardial infarction

Myocardial infarction (MI) leads to the mass death of cardiomyocytes accompanying with the unfavorable alternation of microenvironment, a fibrosis scar deprived of electrical communications, and the lack of blood supply in the infarcted myocardium. The three factors are inextricably intertwined and thus result in a conservative MI therapy efficacy in clinic. A holistic approach pertinently targeted to these three key points would be favorable to rebuild the heart functions. Here, an injectable conductive hydrogel was constructed via in situ Michael addition reaction between multi-armed conductive crosslinker tetraaniline-polyethylene glycol diacrylate (TA-PEG) and thiolated hyaluronic acid (HA-SH). The resultant soft conductive hydrogel with equivalent myocardial conductivity and anti-fatigue performance was loaded with plasmid DNA encoding eNOs (endothelial nitric oxide synthase) nanocomplexes and adipose derived stem cells (ADSCs) for treating MI. The TA-PEG/HA-SH/ADSCs/Gene hydrogel-based holistic system was injected into the infarcted myocardium of SD rats. We demonstrated an increased expression of eNOs in myocardial tissue the heightening of nitrite concentration, accompanied with upregulation of proangiogenic growth factors and myocardium related mRNA. The results of electrocardiography, cardiogram, and histological analysis convincingly revealed a distinct increase of ejection fraction (EF), shortened QRS interval, smaller infarction size, less fibrosis area, and higher vessel density, indicating a significant improvement of heart functions. This conception of combination approach by a conductive injectable hydrogel loaded with stem cells and gene-encoding eNOs nanoparticles will become a robust therapeutic strategy for the treatment of MI.

Scaffold Composition Determines the Angiogenic Outcome of Cell-Based Vascular Endothelial Growth Factor Expression by Modulating Its Microenvironmental Distribution

Delivery of genetically modified cells overexpressing Vascular Endothelial Growth Factor (VEGF) is a promising approach to induce therapeutic angiogenesis in ischemic tissues. The effect of the protein is strictly modulated by its interaction with the components of the extracellular matrix. Its therapeutic potential depends on a sustained but controlled release at the microenvironmental level in order to avoid the formation of abnormal blood vessels. In this study, it is hypothesized that the composition of the scaffold plays a key role in modulating the binding, hence the therapeutic effect, of the VEGF released by 3D-cell constructs. It is found that collagen sponges, which poorly bind VEGF, prevent the formation of localized hot spots of excessive concentration, therefore, precluding the development of aberrant angiogenesis despite uncontrolled expression by a genetically engineered population of adipose tissue-derived stromal cells. On the contrary, after seeding on VEGF-binding egg-white scaffolds, the same cell population caused aberrantly enlarged vascular structures after 14 d. Collagen-based engineered tissues also induced a safe and efficient angiogenesis in both the patch itself and the underlying myocardium in rat models. These findings open new perspectives on the control and the delivery of proangiogenic stimuli, and are fundamental for the vascularization of engineered tissues/organs.

Sustained viral gene delivery from a micro-fibrous, elastomeric cardiac patch to the ischemic rat heart

Biodegradable and elastomeric patches have been applied to the surface of infarcted hearts as temporary mechanical supports to effectively alter adverse left ventricular remodeling processes. In this report, recombinant adeno-associated virus (AAV), known for its persistent transgene expression and low pathogenicity, was incorporated into elastomeric polyester urethane urea (PEUU) and polyester ether urethane urea (PEEUU) and processed by electrospinning into two formats (solid fibers and core-sheath fibers) designed to influence the controlled release behavior. The extended release of AAV encoding green fluorescent protein (GFP) was assessed in vitro. Sustained and localized viral particle delivery was achieved over 2 months in vitro. The biodegradable cardiac patches with or without AAV-GFP were implanted over rat left ventricular lesions three days following myocardial infarction to evaluate the transduction effect of released viral vectors. AAV particles were directly injected into the infarcted hearts as a control. Cardiac function and remodeling were significantly improved for 12 weeks after patch implantation compared to AAV injection. More GFP genes was expressed in the AAV patch group than AAV injection group, with both α-SMA positive cells and cardiac troponin T positive cells transduced in the patch group. Overall, the extended release behavior, prolonged transgene expression, and elastomeric mechanical properties make the AAV-loaded scaffold an attractive option for cardiac tissue engineering where both gene delivery and appropriate mechanical support are desired.

Predictive Nomogram of RAGE Genetic Polymorphisms and Metabolic Risk Factors for Myocardial Infarction Risk in a Han Chinese Population

We investigated the association of 4 well-characterized polymorphisms in receptor for the advanced glycation end-product ( RAGE) gene with myocardial infarction (MI) risk and the changes in metabolic risk factors among 717/612 patients/controls, with the aim of constructing a predictive nomogram. The genotype/allele distributions differed significantly between the 2 groups for T-429C ( Pgenotype/allele = .004/.001) and G1704T ( P < .001/.001). T-429C was significantly associated with MI risk, especially under a recessive model (adjusted odds ratio: 2.24, 95% confidence interval: 1.33-3.79, P = .003). For G1704T, significance was detected under additive (1.37; 1.12-1.67; P = .002) and recessive (3.86; 2.27-6.57; P < .001) models. There were significant differences in blood pressure and low-density lipoprotein cholesterol (LDL-C) across T-429C genotypes and in total cholesterol and LDL-C across G1704T genotypes. The overall best multifactor dimensionality reduction model included dyslipidemia, G1704T, and T-429C. Further predictive nomogram on 2 significant polymorphisms, blood pressure and lipids, showed a better predictive capability (concordance index = 0.716, P < .001). Altogether, we identified 2 polymorphisms of RAGE, T-429C and G1704T, which interacted with metabolic risk factors associated with the occurrence of MI. We also constructed a genetic–metabolic nomogram that can better predict MI risk.

Intramyocardial Injection of Recombinant Adeno-Associated Viral Vector Coexpressing PR39/Adrenomedullin Enhances Angiogenesis and Reduces Apoptosis in a Rat Myocardial Infarction Model

Cotransfer of angiogenic and antiapoptotic genes could be the basis of new gene therapy strategies for myocardial infarction. In this study, rAAV-PR39-ADM, coexpressing antimicrobial peptide (PR39) and adrenomedullin (ADM), was designed with the mediation of recombinant adeno-associated virus. In vitro, CRL-1730 cells were divided into four groups, namely, the sham group, the AAV-null group, the NS (normal saline) group, and the PR39-ADM group. Immunocytochemistry analysis, CCK-8 assays, Matrigel assays, and apoptotic analysis were performed; in vivo, myocardial infarction model was established through ligation of the left coronary artery on rats, and treatment groups corresponded to those used in vitro. Myocardial injury, cardiac performance, and the extent of myocardial apoptosis were assessed. Results suggested that rAAV-PR39-ADM administration after myocardial infarction improved cell viability and cardiac function, attenuated apoptosis and myocardial injury, and promoted angiogenesis. Subsequently, levels of 6×His, HIF-1α, VEGF, p-Akt, Akt, ADM, Bcl-2, and Bax were measured by western blot. rAAV-PR39-ADM increased p-Akt, HIF-1α, and VEGF levels and induced higher Bcl-2 expression and lower Bax expression. In conclusion, our results demonstrate that rAAV-PR39-ADM mitigates myocardial injury by promoting angiogenesis and reducing apoptosis. This study suggests a potential novel gene therapy-based method that could be used clinically for myocardial infarction.

Expression of integrin-linked kinase improves cardiac function in a swine model of myocardial infarction

Previous studies have described the beneficial effects of overexpressing integrin-linked kinase (ILK) after myocardial infarction (MI) in small animal models. However, the effects of ILK in pre-clinical large animals are not known. To move closer to clinical translation, we examined the effects of ILK gene transfer in a swine model of ischemic heart disease. Swine received percutaneous intracoronary injections of adenoviral vector expressing ILK (n=10) or empty ad-null (n=10) in the left anterior descending coronary artery (LAD) following LAD occlusion. Four weeks after transfection, we confirmed that transgene expression was restricted to the infarcted area in the cardiac tissue. Imaging studies demonstrated preserved cardiac function in the ILK group. ILK treatment was associated with reduced infarcted scar size and preserved left ventricular (LV) geometry (LV diameter and LV wall thickness). Enhanced angiogenesis was preserved in the ILK animals, along with reduction of apoptosis. ILK gene therapy improves cardiac remodeling and function in swine following MI associated with increased angiogenesis, reduced apoptosis, and increased cardiomyocyte proliferation with no signs of toxicity. These results may deliver a new approach to treat post-infarct remodeling and subsequent heart failure.

Gene Transfer in Cardiomyocytes Derived from ES and iPS Cells

The advent of human induced pluripotent stem cell (hiPSC) technology has produced patient-specific hiPSC derived cardiomyocytes (hiPSC-CMs) that can be used as a platform to study cardiac diseases and to explore new therapies.The ability to genetically manipulate hiPSC-CMs not only is essential for identifying the structural and/or functional role of a protein but can also provide valuable information regarding therapeutic applications. In this chapter, we describe protocols for culture, maintenance, and cardiac differentiation of hiPSCs. Then, we provide a basic procedure to transduce hiPSC-CMs.

Engineered mesenchymal cell-based patches as controlled VEGF delivery systems to induce extrinsic angiogenesis

Therapeutic over-expression of Vascular Endothelial Growth Factor (VEGF) by transduced progenitors is a promising strategy to efficiently induce angiogenesis in ischemic tissues (e.g. limb muscle and myocardium), but tight control over the micro-environmental distribution of the dose is required to avoid induction of angioma-like tumors. Therapeutic VEGF release was achieved by purified transduced adipose mesenchymal stromal cells (ASC) that homogeneously produce specific VEGF levels, inducing only normal angiogenesis after injection in non-ischemic tissues. However, the therapeutic potential of this approach mostly in the cardiac field is limited by the poor cell survival and the restricted area of effect confined to the cell-injection site. The implantation of cells previously organized in vitro in 3D engineered tissues could overcome these issues. Here we hypothesized that collagen sponge-based construct (patch), generated by ASC expressing controlled VEGF levels, can function as delivery device to induce angiogenesis in surrounding areas (extrinsic vascularization). A 7-mm-thick acellular collagen scaffold (empty), sutured beneath the patch, provided a controlled and reproducible model to clearly investigate the ongoing angiogenesis in subcutaneous mice pockets. VEGF-expressing ASC significantly increased the capillary in-growth inside both the patch itself and the empty scaffold compared to naïve cells, leading to significantly improved survival of implanted cells. These data suggest that this strategy confers control (i) on angiogenesis efficacy and safety by means of ASC expressing therapeutic VEGF levels and (ii) over the treated area through the specific localization in an engineered collagen sponge-based patch.

STATEMENT OF SIGNIFICANCE

Development of efficient pro-angiogenic therapies to restore the micro-vascularization in ischemic tissues is still an open issue. Although extensively investigated, the promising approach based on injections of progenitors transduced to over-express Vascular Endothelial Growth Factor (VEGF) has still several limitations: (i) need of a tight control over the microenvironmental VEGF dose to avoid angioma-like tumor growth; (ii) poor implanted cell survival; (iii) effect area restricted mainly to the injection sites. Here, we aimed to overcome these drawbacks by generating a novel cell-based controlled VEGF delivery device. In particular, transduced mesenchymal cells, purified to release a sustained, safe and efficient VEGF dose, were organized in three-dimensional engineered tissues to improve cell survival and provide a uniform vascularization throughout both the mm-thick implanted constructs themselves and the surrounding area.

Molecular Imaging of Angiogenesis in Cardiac Regeneration

PURPOSE OF REVIEW

Myocardial infarction (MI) leading to heart failure displays an important cause of death worldwide. Adequate restoration of blood flow to prevent this transition is a crucial factor to improve long-term morbidity and mortality. Novel regenerative therapies have been thoroughly investigated within the past decades.

RECENT FINDINGS

Increased angiogenesis in infarcted myocardium has shown beneficial effects on the prognosis of MI; therefore, the proangiogenic capacity of currently tested treatments is of specific interest. Molecular imaging to visualize formation of new blood vessels in vivo displays a promising option to monitor proangiogenic effects of regenerative substances.

SUMMARY

Based on encouraging results in preclinical models, molecular angiogenesis imaging has recently been applied in a small set of patients. This article reviews recent literature on noninvasive in vivo molecular imaging of angiogenesis after MI as an integral part of cardiac regeneration.

Cardiac Regeneration using Growth Factors: Advances and Challenges

Myocardial infarction is the most significant manifestation of ischemic heart disease and is associated with high morbidity and mortality. Novel strategies targeting at regenerating the injured myocardium have been investigated, including gene therapy, cell therapy, and the use of growth factors. Growth factor therapy has aroused interest in cardiovascular medicine because of the regeneration mechanisms induced by these biomolecules, including angiogenesis, extracellular matrix remodeling, cardiomyocyte proliferation, stem-cell recruitment, and others. Together, these mechanisms promote myocardial repair and improvement of the cardiac function. This review aims to address the strategic role of growth factor therapy in cardiac regeneration, considering its innovative and multifactorial character in myocardial repair after ischemic injury. Different issues will be discussed, with emphasis on the regeneration mechanisms as a potential therapeutic resource mediated by growth factors, and the challenges to make these proteins therapeutically viable in the field of cardiology and regenerative medicine. Resumo O infarto do miocárdio representa a manifestação mais significativa da cardiopatia isquêmica e está associado a elevada morbimortalidade. Novas estratégias vêm sendo investigadas com o intuito de regenerar o miocárdio lesionado, incluindo a terapia gênica, a terapia celular e a utilização de fatores de crescimento. A terapia com fatores de crescimento despertou interesse em medicina cardiovascular, devido aos mecanismos de regeneração induzidos por essas biomoléculas, incluindo angiogênese, remodelamento da matriz extracelular, proliferação de cardiomiócitos e recrutamento de células-tronco, dentre outros. Em conjunto, tais mecanismos promovem a reparação do miocárdio e a melhora da função cardíaca. Esta revisão pretende abordar o papel estratégico da terapia, com fatores de crescimento, para a regeneração cardíaca, considerando seu caráter inovador e multifatorial sobre o reparo do miocárdio após dano isquêmico. Diferentes questões serão discutidas, destacando-se os mecanismos de regeneração como recurso terapêutico potencial mediado por fatores de crescimento e os desafios para tornar essas proteínas terapeuticamente viáveis no âmbito da cardiologia e da medicina regenerativa.

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.

Towards comprehensive cardiac repair and regeneration after myocardial infarction: Aspects to consider and proteins to deliver

Ischemic heart disease is a leading cause of death worldwide. After the onset of myocardial infarction, many pathological changes take place and progress the disease towards heart failure. Pathologies such as ischemia, inflammation, cardiomyocyte death, ventricular remodeling and dilation, and interstitial fibrosis, develop and involve the signaling of many proteins. Proteins can play important roles in limiting or countering pathological changes after infarction. However, they typically have short half-lives in vivo in their free form and can benefit from the advantages offered by controlled release systems to overcome their challenges. The controlled delivery of an optimal combination of proteins per their physiologic spatiotemporal cues to the infarcted myocardium holds great potential to repair and regenerate the heart. The effectiveness of therapeutic interventions depends on the elucidation of the molecular mechanisms of the cargo proteins and the spatiotemporal control of their release. It is likely that multiple proteins will provide a more comprehensive and functional recovery of the heart in a controlled release strategy.

Stimulating endogenous cardiac repair

The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration, a combination of these approaches could ameliorate the overall repair process to incorporate the participation of multiple cellular players.

Expression of hypoxia-inducible factor 1 alpha ameliorate myocardial ischemia in rat

Hypoxia-inducible factor 1 alpha (HIF-1a), the upstream regulator of Vascular endothelial growth factor (VEGF), is the vital hypoxia related gene expression control factor. To evaluate HIF-1a therapeutic efficacy to acute myocardial infarction, the HIF-1a expressing recombinant Adeno-associated virus (rAAV) was constructed. The Wistar rat ischemic heart animal model was established with left anterior descending coronary artery ligation. The ischemic rats were treated with HIF-1a expressing and GFP expressing rAAVs respectively. Four weeks post the injection, the cardiac function of treated rat was compared by TM_WAVE system; size of infracted area was calculated by Evan's blue stain and capillary density was determined by CD31 immunohistochemical staining. Compare to the control group, the rats received HIF-1a expressing rAAV have smaller infracted heart size, the better heart function and higher capillary density than vehicle control group. The results show that the injection of HIF1a expressing rAAV can improve cardiac function and ameliorate acute myocardial ischemia (AMI) in rats.

AAV-mediated gene therapy for atherosclerosis

The prognosis of patients with coronary artery disease and stroke has improved substantially over the last decade as a result of advances in primary and secondary preventive care as well as novel interventional approaches, including the development of drug-eluting stents and balloons. Despite this progress, however, cardiovascular disease remains the leading cause of death in industrialized nations. Sustained efforts to elucidate the underlying mechanisms of atherogenesis, reperfusion-induced cardiac injury, and ischemic heart failure have led to the identification of several target genes as key players in the development and progression of atherosclerotic vascular disease. This knowledge has now enabled genetic therapeutic modulation not only for inherited diseases with a single gene defect, such as familial hypercholesterolemia, but also for multifactorial disorders. This review will focus on approaches in adeno-associated viral (AAV)-mediated gene therapy for atherosclerosis and its long-term sequelae.

Gene therapy to restore electrophysiological function in heart failure

INTRODUCTION

Heart failure (HF) is a major public health epidemic and a leading cause of morbidity and mortality in the industrialized world. Existing treatments for patients with HF are often associated with pro-arrhythmic activity and risk of sudden cardiac death. Therefore, development of novel, effective and safe therapeutic options for HF patients is a critical area of unmet need.

AREAS COVERED

In this article, we review recent advances in the emerging field of cardiac gene therapy for the treatment of tachy- and bradyarrhythmias in HF. We provide an overview of gene-based approaches that modulate myocardial conduction, repolarization, calcium cycling and adrenergic signaling to restore heart rate and rhythm.

EXPERT OPINION

We highlight major advantages of gene therapy for arrhythmias, including the ability to selectively target specific cell populations and to limit the therapeutic effect to the region that requires modification. We illustrate how advances in our fundamental understanding of the molecular origins of arrhythmogenic disorders are allowing investigators to use targeted gene-based approaches to successfully correct abnormal excitability in the atria, ventricles and conduction system. Translation of various gene therapy approaches to humans may revolutionize our ability to combat lethal arrhythmias in HF patients.

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.

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.