Exploring the Therapeutic Potential of Gene Therapy in Arrhythmogenic Right Ventricular Cardiomyopathy.

Right dominant arrhythmogenic cardiomyopathy, commonly known as Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), represents a formidable challenge in cardiovascular medicine, as conventional therapies are commonly ineffective in impeding disease progression and the development of end-stage heart failure. Recombinant adeno-associated virus (AAV)-mediated gene therapy presents a promising avenue for targeted therapeutic interventions, potentially revolutionising treatment approaches for ARVC patients. Encouraging results from preclinical studies have sparked optimism about the possibility of curing specific subtypes of ARVC in the near future. This narrative review delves into the dynamic landscape of genetic therapy for ARVC, elucidating its underlying mechanisms and developmental stages, and providing updates on forthcoming trials. Additionally, it examines the hurdles and complexities impeding the successful translation of ARVC genetic therapies into clinical practice. Despite notable scientific advancements, the journey towards implementing genetic therapies for ARVC patients in real-world clinical settings is still in its early phases.

Focal Anticoagulation by Somatic Gene Transfer: Towards Preventing Cardioembolic Stroke.

Cardioembolic stroke (CS) has emerged as a leading cause of ischaemic stroke (IS); distinguished by thrombi embolising to the brain from cardiac origins; most often from the left atrial appendage (LAA). Contemporary therapeutic options are largely dependent on systemic anticoagulation as a blanket preventative strategy, yet this does not represent a nuanced or personalised solution. Contraindications to systemic anticoagulation create significant unmedicated and high-risk cohorts, leaving these patients at risk of significant morbidity and mortality. Atrial appendage occlusion devices are increasingly used to mitigate stroke risk from thrombi emerging from the LAA in patients ineligible for oral anticoagulants (OACs). Their use, however, is not without risk or significant cost, and does not address the underlying aetiology of thrombosis and CS. Viral vector-based gene therapy has emerged as a novel strategy to target a spectrum of haemostatic disorders, achieving success through the adeno-associated virus (AAV) based therapy of haemophilia. Yet, thrombotic disorders, such as CS, have had limited exploration within the realm of AAV gene therapy approaches-presenting a gap in the literature and an opportunity for further research. Gene therapy has the potential to directly address the cause of CS by localised targeting of the molecular remodelling that serves to promote thrombosis.

Delivery of Cardioactive Therapeutics in a Porcine Myocardial Infarction Model.

Myocardial infarction is one of the leading causes of death and disability worldwide, and there is an urgent need for novel cardioprotective or regenerative strategies. An essential component of drug development is determining how a novel therapeutic is to be administered. Physiologically relevant large animal models are of critical importance in assessing the feasibility and efficacy of various therapeutic delivery strategies. Due to their similarities to humans in cardiovascular physiology, coronary vascular anatomy, and heart weight to body weight ratio, swine is one of the preferred species in the preclinical evaluation of new therapies for myocardial infarction. The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. After percutaneously induced myocardial infarction, female landrace swine received treatment with novel agents through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump. The procedures employed for each technique are reproducible, resulting in reliable cardioactive drug delivery. These models can be easily adapted to suit individual study designs, and each of these delivery techniques can be used to investigate a variety of possible interventions. Therefore, these methods are a useful tool for translational scientists pursuing novel biological approaches in cardiac repair following myocardial infarction.

ß 3 Adrenergic Receptor Stimulation Promotes Reperfusion in Ischemic Limbs in a Murine Diabetic Model.

Aims/Hypothesis: Peripheral arterial disease (PAD) is a major burden, resulting in limb claudication, repeated surgical interventions and amputation. There is an unmet need for improved medical management of PAD that improves quality of life, maintains activities of daily life and reduces complications. Nitric oxide (NO)/redox balance is a key regulator of angiogenesis. We have previously shown beneficial effects of a ß 3 adrenergic receptor (ß 3AR) agonist on NO/redox balance. We hypothesized that ß 3AR stimulation would have therapeutic potential in PAD by promoting limb angiogenesis. Methods: The effect of the ß 3AR agonist CL 316,243 (1-1,000 nmol/L in vitro, 1 mg/kg/day s. c) was tested in established angiogenesis assays with human endothelial cells and patient-derived endothelial colony forming cells. Post-ischemia reperfusion was determined in streptozotocin and/or high fat diet-induced diabetic and non-diabetic mice in vivo using the hind limb ischemia model. Results: CL 316,243 caused accelerated recovery from hind limb ischemia in non-diabetic and type 1 and 2 diabetic mice. Increased eNOS activity and decreased superoxide generation were detected in hind limb ischemia calf muscle from CL 316, 243 treated mice vs. controls. The protective effect of CL 316,243 in diabetic mice was associated with >50% decreases in eNOS glutathionylation and nitrotyrosine levels. The ß 3AR agonist directly promoted angiogenesis in endothelial cells in vitro. These pro-angiogenic effects were ß 3AR and NOS-dependent. Conclusion/Interpretation: ß 3AR stimulation increased angiogenesis in diabetic ischemic limbs, with demonstrable improvements in NO/redox balance and angiogenesis elicited by a selective agonist. The orally available ß 3AR agonist, Mirabegron, used for overactive bladder syndrome, makes translation to a clinical trial by repurposing of a ß 3AR agonist to target PAD immediately feasible.

The multiple roles of chemokines in the mechanisms of stent biocompatibility.

While the advent of drug-eluting stents has been clinically effective in substantially reducing the rates of major stent-related adverse events compared with bare metal stents, vascular biological problems such as neointimal hyperplasia, delayed re-endothelialization, late stent thrombosis are not eliminated and, increasingly, neoatherosclerosis is the underlying mechanism for very late stent failure. Further understanding regarding the mechanisms underlying the biological responses to stent deployment is therefore required so that new and improved therapies can be developed. This review will discuss the accumulating evidence that the chemokines, small inflammatory proteins, play a role in each key biological process of stent biocompatibility. It will address the chemokine system in its specialized roles in regulating the multiple facets of vascular biocompatibility including neointimal hyperplasia, endothelial progenitor cell (EPC) mobilization and re-endothelialization after vascular injury, platelet activation and thrombosis, as well as neoatherosclerosis. The evidence in this review suggests that chemokine-targeting strategies may be effective in controlling the pathobiological processes that lead to stent failure. Preclinical studies provide evidence that inhibition of specific chemokines and/or broad-spectrum inhibition of the CC-chemokine class prevents neointimal hyperplasia, reduces thrombosis and suppresses the development of neoatherosclerosis. In contrast, however, to these apparent deleterious effects of chemokines on stent biocompatibility, the CXC chemokine, CXCL12, is essential for the mobilization and recruitment of EPCs that make important contributions to re-endothelialization post-stent deployment. This suggests that future chemokine inhibition strategies would need to be correctly targeted so that all key stent biocompatibility areas could be addressed, without compromising important adaptive biological responses.

Gene and Cell Therapy for Cardiac Arrhythmias.

PURPOSE: In the last decade, interest in gene therapy as a therapeutic technology has increased, largely driven by an exciting yet modest number of successful applications for monogenic diseases. Setbacks in the use of gene therapy for cardiac disease have motivated efforts to develop vectors with enhanced tropism for the heart and more efficient delivery methods. Although monogenic diseases are the logical target, cardiac arrhythmias represent a group of conditions amenable to gene therapy because of focal targets (biological pacemakers, nodal conduction, or stem cell-related arrhythmias) or bystander effects on cells not directly transduced because of electrical coupling. METHODS: This review provides a contemporary narrative of the field of gene therapy for experimental cardiac arrhythmias, including those associated with stem cell transplant. Recent articles published in the English language and available through the PubMed database and other prominent literature are discussed. FINDINGS: The promise of gene therapy has been realized for a handful of monogenic diseases and is actively being pursued for cardiac applications in preclinical models. With improved vectors, it is likely that cardiac disease will also benefit from this technology. Cardiac arrhythmias, whether inherited or acquired, are a group of conditions with a potentially lower threshold for phenotypic correction and as such hold unique potential as targets for cardiac gene therapy. IMPLICATIONS: There has been a proliferation of research on the potential of gene therapy for cardiac arrhythmias. This body of investigation forms a strong basis on which further developments, particularly with viral vectors, are likely to help this technology progress along its translational trajectory.

Broad-spectrum chemokine inhibition blocks inflammation-induced angiogenesis, but preserves ischemia-driven angiogenesis.

M3 is a broad-spectrum chemokine-binding protein that inactivates inflammatory chemokines, including CCL2, CCL5, and CX3CL1. The aim of this study was to compare whether M3 could inhibit angiogenesis driven by inflammation or ischemia. Here, apolipoprotein E-/- mice were injected with adenoviral M3 (AdM3) or control adenoviral green fluorescent protein (AdGFP) 3 d prior to stimulating angiogenesis using 2 established models that distinctly represent inflammatory or ischemia-driven angiogenesis, namely the periarterial femoral cuff and hind limb ischemia. AdM3 reduced intimal thickening, adventitial capillary density, and macrophage accumulation in femoral arteries 21 d after periarterial femoral cuff placement compared with AdGFP-treated mice (P < 0.05). AdM3 also reduced mRNA expression of proangiogenic VEGF, inflammatory markers IL-6 and IL-1ß, and vascular smooth muscle cell (VSMC)-activated synthetic markers Krüppel-like family of transcription factor 4 (KLF4) and platelet-derived growth factor receptor ß (PDGFRß) in the inflammatory cuff model. In contrast, capillary density, VSMC content, blood flow perfusion, and VEGF gene expression were unaltered between groups in skeletal muscle following hind limb ischemia. In vitro, AdM3 significantly reduced human microvascular endothelial cell 1 proliferation, migration, and tubule formation by ∼17, 71.3, and 8.7% (P < 0.05) in macrophage-conditioned medium associating with reduced VEGF and hypoxia-inducible factor 1α mRNA but not in hypoxia (1% O2). Compared with AdGFP, AdM3 also inhibited VSMC proliferation and migration and reduced mRNA expression of KLF4 and PDGFRß under inflammatory conditions. In contrast, AdM3 had no effect on VSMC processes in response to hypoxia in vitro. Our findings show that broad-spectrum inhibition of inflammatory chemokines by M3 inhibits inflammatory-driven but not ischemia-driven angiogenesis, presenting a novel strategy for the treatment of diseases associated with inflammatory-driven angiogenesis.-Ravindran, D., Cartland, S. P., Bursill, C. A., Kavurma, M. M. Broad-spectrum chemokine inhibition blocks inflammation-induced angiogenesis, but preserves ischemia-driven angiogenesis.

Chemokine binding protein 'M3' limits atherosclerosis in apolipoprotein E-/- mice.

Chemokines are important in macrophage recruitment and the progression of atherosclerosis. The 'M3' chemokine binding protein inactivates key chemokines involved in atherosclerosis (e.g. CCL2, CCL5 and CX3CL1). We aimed to determine the effect of M3 on plaque development and composition. In vitro chemotaxis studies confirmed that M3 protein inhibited the activity of chemokines CCL2, CCL5 and CX3CL1 as primary human monocyte migration as well as CCR2-, CCR5- and CX3CR1-directed migration was attenuated by M3. In vivo, adenoviruses encoding M3 (AdM3) or green fluorescence protein (AdGFP; control) were infused systemically into apolipoprotein (apo)-E-/- mice. Two models of atherosclerosis development were used in which the rate of plaque progression was varied by diet including: (1) a 'rapid promotion' model (6-week high-fat-fed) and (2) a 'slow progression' model (12-week chow-fed). Plasma chemokine activity was suppressed in AdM3-infused mice as indicated by significantly less monocyte migration towards AdM3 mouse plasma ex vivo (29.56%, p = 0.014). In the 'slow progression' model AdM3 mice had reduced lesion area (45.3%, p = 0.035) and increased aortic smooth muscle cell α-actin expression (60.3%, p = 0.014). The reduction in lesion size could not be explained by changes in circulating inflammatory monocytes as they were higher in the AdM3 group. In the 'rapid promotion' model AdM3 mice had no changes in plaque size but reduced plaque macrophage content (46.8%, p = 0.006) and suppressed lipid deposition in thoracic aortas (66.9%, p<0.05). There was also a reduction in phosphorylated p65, the active subunit of NF-κb, in the aortas of AdM3 mice (37.3%, p<0.0001). M3 inhibited liver CCL2 concentrations in both models with no change in CCL5 or systemic chemokine levels. These findings show M3 causes varying effects on atherosclerosis progression and plaque composition depending on the rate of lesion progression. Overall, our studies support a promising role for chemokine inhibition with M3 for the treatment of atherosclerosis.

CC-chemokine class inhibition attenuates pathological angiogenesis while preserving physiological angiogenesis.

Increasing evidence shows that CC-chemokines promote inflammatory-driven angiogenesis, with little to no effect on hypoxia-mediated angiogenesis. Inhibition of the CC-chemokine class may therefore affect angiogenesis differently depending on the pathophysiological context. We compared the effect of CC-chemokine inhibition in inflammatory and physiological conditions. In vitro, the broad-spectrum CC-chemokine inhibitor "35K" inhibited inflammatory-induced endothelial cell proliferation, migration, and tubulogenesis, with more modest effects in hypoxia. In vivo, adenoviruses were used to overexpress 35K (Ad35K) and GFP (AdGFP, control virus). Plasma chemokine activity was suppressed by Ad35K in both models. In the periarterial femoral cuff model of inflammatory-driven angiogenesis, overexpression of 35K inhibited adventitial neovessel formation compared with control AdGFP-infused mice. In contrast, 35K preserved neovascularization in the hindlimb ischemia model and had no effect on physiological neovascularization in the chick chorioallantoic membrane assay. Mechanistically, 2 key angiogenic proteins (VEGF and hypoxia-inducible factor-1α) were conditionally regulated by 35K, such that expression was inhibited in inflammation but was unchanged in hypoxia. In conclusion, CC-chemokine inhibition by 35K suppresses inflammatory-driven angiogenesis while preserving physiological ischemia-mediated angiogenesis via conditional regulation of VEGF and hypoxia-inducible factor-1α. CC-chemokine inhibition may be an alternative therapeutic strategy for suppressing diseases associated with inflammatory angiogenesis without inducing the side effects caused by global inhibition.- Ridiandries, A., Tan, J. T. M., Ravindran, D., Williams, H., Medbury, H. J., Lindsay, L., Hawkins, C., Prosser, H. C. G., Bursill, C. A. CC-chemokine class inhibition attenuates pathological angiogenesis while preserving physiological angiogenesis.