Adenoviral intramyocardial VEGF-DΔNΔC gene transfer increases myocardial perfusion reserve in refractory angina patients: a phase I/IIa study with 1-year follow-up

The evolving cardiac lymphatic vasculature in development, repair and regeneration

The lymphatic vasculature has an essential role in maintaining normal fluid balance in tissues and modulating the inflammatory response to injury or pathogens. Disruption of normal development or function of lymphatic vessels can have severe consequences. In the heart, reduced lymphatic function can lead to myocardial oedema and persistent inflammation. Macrophages, which are phagocytic cells of the innate immune system, contribute to cardiac development and to fibrotic repair and regeneration of cardiac tissue after myocardial infarction. In this Review, we discuss the cardiac lymphatic vasculature with a focus on developments over the past 5 years arising from the study of mammalian and zebrafish model organisms. In addition, we examine the interplay between the cardiac lymphatics and macrophages during fibrotic repair and regeneration after myocardial infarction. Finally, we discuss the therapeutic potential of targeting the cardiac lymphatic network to regulate immune cell content and alleviate inflammation in patients with ischaemic heart disease.

Clinical Application of Novel Therapies for Coronary Angiogenesis: Overview, Challenges, and Prospects

Cardiovascular diseases continue to be the leading cause of death worldwide, with ischemic heart disease as the most significant contributor. Pharmacological and surgical interventions have improved clinical outcomes, but are unable to ameliorate advanced stages of end-heart failure. Successful preclinical studies of new therapeutic modalities aimed at revascularization have shown short lasting to no effects in the clinical practice. This lack of success may be attributed to current challenges in patient selection, endpoint measurements, comorbidities, and delivery systems. Although challenges remain, the field of therapeutic angiogenesis is evolving, as novel strategies and bioengineering approaches emerge to optimize delivery and efficacy. Here, we describe the structure, vascularization, and regulation of the vascular system with particular attention to the endothelium. We proceed to discuss preclinical and clinical findings and present challenges and future prospects in the field.

Efficacy and Safety of Clinical-Grade Human Vascular Endothelial Growth Factor-DΔNΔC Gene Therapy Containing Residual Replication-Competent Adenoviruses

Biological bypass through induced angiogenesis by vascular endothelial growth factor D (VEGF-D) gene therapy (GT) is a new concept for the treatment of cardiac ischemia. Serotype 5 adenoviruses are used in the clinical trials for transferring the VEGF-D cDNA into the ischemic myocardium. However, the presence of replication-competent vectors in the adenovirus products is a widely recognized problem that may pose a potential safety risk to the treated patients. We compared three different VEGF-D GT production lots containing different levels of replication-competent adenoviruses (RCA) tested in 3 × 10¹⁰ viral particles (vp): <10 RCA (VEGF-D L-RCA1), 10-100 RCA (VEGF-D H-RCA2), and 100-200 RCA (VEGF-D H-RCA3), as measured by a novel droplet digital polymerase chain reaction (PCR) RCA assay in a preclinical rabbit model (n = 21). β-galactosidase encoding nonclinical-grade preparation was used as a nonangiogenic control. Each preparation was injected into the right semimembranosus muscle using dose of 1 × 10¹¹ vp. Efficacy of the products was tested by the combination of contrast pulse sequencing ultrasound and modified Miles assay as well as quantifying the total cross-sectional area of capillaries. Safety, immunogenicity, toxicity, biodistribution, and shedding were assessed by general histology, serial measurements of C-reactive protein, white blood cell count and body temperature as well as using quantitative real-time PCR with primers targeted to the VEGF-D and replication-permitting E1 sequences. We found no significant differences in the efficacy or safety between the study groups. Most importantly, no detectable presence of RCA-specific E1 sequence was found in any samples tested, indicating that no detectable vector replication took place in vivo. We conclude that relatively low levels of RCA in adenoviral GT products may not be as important major safety issue as previously anticipated.

The vasculature: a therapeutic target in heart failure?

It is well established that the vasculature plays a crucial role in maintaining oxygen and nutrients supply to the heart. Increasing evidence further suggest that the microcirculation has additional roles in supporting a healthy microenvironment. Heart failure is well known to be associated with changes and functional impairment of the microvasculature. The specific ablation of protective signals in endothelial cells in experimental models is sufficient to induce heart failure. Therefore, restoring a healthy endothelium and microcirculation may be a valuable therapeutic strategy to treat heart failure. The present review article will summarize the current understanding of the vascular contribution to heart failure with reduced or preserved ejection fraction. Novel therapeutic approaches including next generation pro-angiogenic therapies and non-coding RNA therapeutics, as well as the targeting of metabolites or metabolic signaling, vascular inflammation and senescence will be discussed.

Role of Cardiac Lymphatics in Myocardial Edema and Fibrosis: JACC Review Topic of the Week

The cardiac lymphatic network plays a key role in regulation of myocardial extracellular volume and immune cell homeostasis. In different pathological conditions cardiac lymphatics undergo significant remodeling, with insufficient lymphatic function and/or lymphangiogenesis leading to fluid accumulation and development of edema. Additionally, by modulating the reuptake of tissue-infiltrating immune cells, lymphatics regulate immune responses. Available evidence suggests that both edema and inadequate immune response resolution may contribute to extracellular matrix remodeling and interstitial myocardial fibrosis. Interestingly, stimulation of lymphangiogenesis has been shown to improve cardiac function and reduce the progression of myocardial fibrosis during heart failure development after myocardial infarction. This review goes through the available clinical and experimental data supporting a role for cardiac lymphatics in cardiac disease, focusing on the current evidence linking poor cardiac lymphatic transport to the fibrogenic process and discussing potential avenues for novel biomarkers and therapeutic targets to limit cardiac fibrosis and dysfunction.

BMP6/TAZ-Hippo signaling modulates angiogenesis and endothelial cell response to VEGF

The BMP/TGFβ-Smad, Notch and VEGF signaling guides formation of endothelial tip and stalk cells. However, the crosstalk of bone morphogenetic proteins (BMPs) and vascular endothelial growth factor receptor 2 (VEGFR2) signaling has remained largely unknown. We demonstrate that BMP family members regulate VEGFR2 and Notch signaling, and act via TAZ-Hippo signaling pathway. BMPs were found to be regulated after VEGF gene transfer in C57/Bl6 mice and in a porcine myocardial ischemia model. BMPs 2/4/6 were identified as endothelium-specific targets of VEGF. BMP2 modulated VEGF-mediated endothelial sprouting via Delta like Canonical Notch Ligand 4 (DLL4). BMP6 modulated VEGF signaling by regulating VEGFR2 expression and acted via Hippo signaling effector TAZ, known to regulate cell survival/proliferation, and to be dysregulated in cancer. In a matrigel plug assay in nude mice BMP6 was further demonstrated to induce angiogenesis. BMP6 is the first member of BMP family found to directly regulate both Hippo signaling and neovessel formation. It may thus serve as a target in pro/anti-angiogenic therapies.

The Effect of Residual Triton X-100 on Structural Stability and Infection Activity of Adenovirus Particles

To ensure the high purity and biological activity of the adenovirus vector to be used for clinical applications, a stable and linearly scalable preparation method is highly imperative. During the adenovirus-harvesting process, the Triton X-100-based lysis method possesses the advantages of higher efficiency as well as easier linearization and amplification. Most Triton X-100 can be removed from the adenovirus sample by chromatographic purification. However, there is no report that a small amount of residual Triton X-100, present in adenovirus sample, can affect the particle integrity, infectivity, and structure of adenoviruses. Here, we found that although residual Triton X-100 affected the short-term stability, purity, infectivity, and structure of adenoviruses at 37°C, it did not hamper these properties of adenoviruses at 4°C. This study suggests that although the Triton X-100-based lysis method is a simple, efficient, and easy-to-scale process for lysing host cells to release the adenovirus, the storage conditions of adenovirus products must be taken into consideration.

An evidence map of randomised controlled trials evaluating genetic therapies

OBJECTIVES

Genetic therapies replace or inactivate disease-causing genes or introduce new or modified genes. These therapies have the potential to cure in a single application rather than treating symptoms through repeated administrations. This evidence map provides a broad overview of the genetic therapies that have been evaluated in randomised controlled trials (RCTs) for efficacy and safety.

ELIGIBILITY CRITERIA

Two independent reviewers screened publications using predetermined eligibility criteria. Study details and data on safety and efficacy were abstracted from included trials. Results were visualised in an evidence map.

INFORMATION SOURCES

We searched PubMed, EMBASE, Web of Science, ClinicalTrials.gov and grey literature to November 2018.

RISK OF BIAS

Only RCTs were included in this review to reduce the risk of selection bias in the evaluation of genetic therapy safety and efficacy.

INCLUDED STUDIES

We identified 119 RCTs evaluating genetic therapies for a variety of clinical conditions.

SYNTHESIS OF RESULTS

On average, samples included 107 participants (range: 1-1022), and were followed for 15 months (range: 0-124). Interventions using adenoviruses (40%) to treat cardiovascular diseases (29%) were the most common.

DESCRIPTION OF THE EFFECT

In RCTs reporting safety and efficacy outcomes, in the majority (60%) genetic therapies were associated with improved symptoms but in nearly half (45%) serious adverse event (SAEs) were also reported. Improvement was reported in trials treating cancer, cardiovascular, ocular and muscular diseases. However, only 19 trials reported symptom improvement for at least 1 year.

STRENGTHS AND LIMITATIONS OF EVIDENCE

This is the first comprehensive evidence map of RCTs evaluating the safety and efficacy of genetic therapies. Evidence for long-term effectiveness and safety is still sparse. This lack of evidence has implications for the use, ethics, pricing and logistics of genetic therapies.

INTERPRETATION

This evidence map provides a broad overview of research studies that allow strong evidence statements regarding the safety and efficacy of genetic therapies. Most interventions improve symptoms, but SAE are also common. More research is needed to evaluate genetic therapies with regard to the potential to cure diseases.

Comparison of Efficiency and Function of Vascular Endothelial Growth Factor Adenovirus Vectors in Endothelial Cells for Gene Therapy of Placental Insufficiency

Severe fetal growth restriction (FGR) affects 1:500 pregnancies, is untreatable and causes serious neonatal morbidity and death. Reduced uterine blood flow (UBF) and lack of bioavailable VEGF due to placental insufficiency is a major cause. Transduction of uterine arteries in normal or FGR sheep and guinea pigs using an adenovirus (Ad) encoding VEGF isoforms A (Ad.VEGF-A165) and a FLAG-tagged pre-processed short form D (DΔNΔC, Ad.VEGF-DΔNΔC-FLAG) increases endothelial nitric oxide expression, enhances relaxation and reduces constriction of the uterine arteries and their branches. UBF and angiogenesis are increased long term, improving fetal growth in utero. For clinical trial development we compared Ad.VEGF vector transduction efficiency and function in endothelial cells (ECs) derived from different species. We aimed to compare the transduction efficiency and function of the pre-clinical study Ad. constructs (Ad.VEGF-A165, Ad.VEGF-DΔNΔC-FLAG) with the intended clinical trial construct (Ad.VEGF-DΔNΔC) where the FLAG tag is removed. We infected ECs from human umbilical vein, pregnant sheep uterine artery, pregnant guinea pig aorta and non-pregnant rabbit aorta, with increasing multiplicity of infection (MOI) for 24 or 48 hours of three Ad.VEGF vectors, compared to control Ad. containing the LacZ gene (Ad.LacZ). VEGF supernatant expression was analysed by ELISA. Functional assessment used tube formation assay and Erk-Akt phosphorylation by ELISA. VEGF expression was higher after Ad.VEGF-DΔNΔC-FLAG and Ad.VEGF-DΔNΔC transduction compared to Ad.VEGF-A165 in all EC types (*p < 0.001). Tube formation was higher in ECs transduced with Ad.VEGF-DΔNΔC in all species compared to other constructs (***p < 0.001, *p < 0.05 with rabbit aortic ECs). Phospho-Erk and phospho-Akt assays displayed no differences between the three vector constructs, whose effect was, as in other experiments, higher than Ad.LacZ (***p < 0.001). In conclusion, we observed high transduction efficiency and functional effects of Ad.VEGF-DΔNΔC vector with comparability in major pathway activation to constructs used in pre-clinical studies, supporting its use in a clinical trial.

Endothelial sprouting, proliferation, or senescence: tipping the balance from physiology to pathology

Therapeutic modulation of vascular cell proliferation and migration is essential for the effective inhibition of angiogenesis in cancer or its induction in cardiovascular disease. The general view is that an increase in vascular growth factor levels or mitogenic stimulation is beneficial for angiogenesis, since it leads to an increase in both endothelial proliferation and sprouting. However, several recent studies showed that an increase in mitogenic stimuli can also lead to the arrest of angiogenesis. This is due to the existence of intrinsic signaling feedback loops and cell cycle checkpoints that work in synchrony to maintain a balance between endothelial proliferation and sprouting. This balance is tightly and effectively regulated during tissue growth and is often deregulated or impaired in disease. Most therapeutic strategies used so far to promote vascular growth simply increase mitogenic stimuli, without taking into account its deleterious effects on this balance and on vascular cells. Here, we review the main findings on the mechanisms controlling physiological vascular sprouting, proliferation, and senescence and how those mechanisms are often deregulated in acquired or congenital cardiovascular disease leading to a diverse range of pathologies. We also discuss alternative approaches to increase the effectiveness of pro-angiogenic therapies in cardiovascular regenerative medicine.

Refractory Angina-Unsolved Problem

The article discusses pharmacologic and interventional therapeutic options for patients with refractory angina. Refractory angina refers to long-lasting symptoms (≥3 months) due to established reversible ischemia in the presence of obstructive coronary artery disease, which cannot be controlled by escalating medical therapy with second-line and third-line pharmacologic agents, bypass grafting, or stenting. Due to an aging population, increased number of comorbidities, and advances in coronary artery disease treatment, incidence of refractory angina is growing. Although the number of therapeutic options is increasing, there is a lack of randomized clinical trials that could help create recommendations for this group of patients.

Current Understanding of Circulating Biomarkers in Pulmonary Hypertension Due to Left Heart Disease

Pulmonary hypertension due to left heart disease (PH-LHD; Group 2), especially in the setting of heart failure with preserved ejection fraction (HFpEF), is the most frequent cause of PH. Despite its prevalence, no effective therapies for PH-LHD are available at present. This is largely due to the lack of a concise definition for hemodynamic phenotyping, existence of significant gaps in the understanding of the underlying pathology and the impact of associated comorbidities, as well as the absence of specific biomarkers that can aid in the early diagnosis and management of this challenging syndrome. Currently, B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are guideline-recommended biomarkers for the diagnosis and prognosis of heart failure (HF) and PH. Endothelin-1 (ET-1), vascular endothelial growth factor-D (VEGF-D), and microRNA-206 have also been recently identified as new potential circulating biomarkers for patients with PH-LHD. In this review, we aim to present the current state of knowledge of circulating biomarkers that can be used to guide future research toward diagnosis, refine specific patient phenotype, and develop therapeutic approaches for PH-LHD, with a particular focus on PH-HFpEF. Potential circulating biomarkers identified in pre-clinical models of PH-LHD are also summarized here.

Refractory Angina: From Pathophysiology to New Therapeutic Nonpharmacological Technologies

Despite optimal combination of guideline-directed anti-ischemic therapies and myocardial revascularization, a substantial proportion of patients with stable coronary artery disease continues to experience disabling symptoms and is often referred as "no-option." The appraisal of the pathways linking ischemia to symptom perception indicates a complex model of heart-brain interactions in the generation of the subjective anginal experience and inspired novel approaches that may be clinically effective in alleviating the angina burden of this population. Conversely, the prevailing ischemia-centered view of angina, with the focus on traditional myocardial revascularization as the sole option to address ischemia on top of medical therapy, hinders the experimental characterization and broad-scale clinical implementation of strongly needed therapeutic options. The interventionist, often the first physician to establish the diagnosis of refractory angina pectoris (RAP) following coronary angiography, should be aware of the numerous emerging technologies with the potential to improve quality of life in the growing population of RAP patients. This review describes the current landscape and the future perspectives on nonpharmacological treatment technologies for patients with RAP, with a view on the underlying physiopathological rationale and current clinical evidence.

Progress of Gene Therapy in Cardiovascular Disease

Gene therapy has been extensively studied in peripheral and cardiac ischemia, heart and vein graft failure, and dyslipidemia, but most clinical trials failed to show their efficacies despite good outcomes in preclinical studies. So far, 2 gene therapies for dyslipidemia and one for critical limb ischemia in peripheral artery disease have been approved. In critical limb ischemia, gene therapy using proangiogenic factors has emerged as a novel therapeutic modality for promoting angiogenesis. Initial researches mainly focused on vascular endothelial growth factor, fibroblast growth factor, or hepatocyte growth factor. After the favorable results of basic research, several phase I and II clinical trials of these proangiogenic factors have shown promising results. However, only a phase III clinical trial of the intramuscular injection of hepatocyte growth factor plasmid DNA has shown successful outcomes, and it was recently approved in Japan for treating patients with critical limb ischemia who have ulcers and for whom no alternative therapeutic options are available. DNA vaccine is another promising modality of gene therapy. An antitumor vaccine suppressing angiogenesis through the inhibition of proangiogenic factors and an antihypertensive vaccine inhibiting the renin–angiotensin system are representative DNA vaccines. The advantage of DNA vaccine is its long-term effectiveness with a few vaccinations; however, the benefits and risks, such as adverse T-cell reaction against self-antigen or long-term side effects, of DNA vaccines should be carefully evaluated. In this review, we discuss the recent advances in proangiogenic gene therapy for critical limb ischemia and DNA vaccine for hypertension.

Double VEGF/HGF Gene Therapy in Critical Limb Ischemia Complicated by Diabetes Mellitus

Critical leg ischemia (CLI) complicated by diabetes mellitus (DM), which is a very common and dangerous disease, represents the ultimate stage of peripheral arterial disease. Patients are treated with antiplatelet drugs, statins and limb revascularization, but a significant number of patients are not candidate for revascularization. Literature shows that in such cases, gene therapy could be a perfect therapeutic option. The aim of our study was to evaluate efficacy of double vascular endothelial growth factor/hepatocyte growth factor (VEGF/HGF) gene therapy in patients with CLI complicated by DM. We observed that 90 days after administration, serum level of VEGF and ankle-brachial index increased significantly (p < 0.001) and rest pain decreased significantly compared with the control group (p < 0.002). Moreover considerable improvement in vascularization was observed in computed tomography angiography (P = 0.04). Based on the results of this study, we suggest that the therapy with pIRES/VEGF165/HGF bicistronic plasmid administration is a safe and effective method of treatment of patients with both CLI and DM. Graphical abstract.

Coronary vessel formation in development and disease: mechanisms and insights for therapy

The formation of new blood vessels after myocardial infarction (MI) is essential for the survival of existing and regenerated cardiac tissue. However, the extent of endogenous revascularization after MI is insufficient, and MI can often result in ventricular remodelling, progression to heart failure and premature death. The neutral results of numerous clinical trials that have evaluated the efficacy of angiogenic therapy to revascularize the infarcted heart reflect our poor understanding of the processes required to form a functional coronary vasculature. In this Review, we describe the latest advances in our understanding of the processes involved in coronary vessel formation, with mechanistic insights taken from developmental studies. Coronary vessels originate from multiple cellular sources during development and form through a number of distinct and carefully orchestrated processes. The ectopic reactivation of developmental programmes has been proposed as a new paradigm for regenerative medicine, therefore, a complete understanding of these processes is crucial. Furthermore, knowledge of how these processes differ between the embryonic and adult heart, and how they might be more closely recapitulated after injury are critical for our understanding of regenerative biology, and might facilitate the identification of tractable molecular targets to therapeutically promote neovascularization and regeneration of the infarcted heart.

Oxidative Stress and New Pathogenetic Mechanisms in Endothelial Dysfunction: Potential Diagnostic Biomarkers and Therapeutic Targets

Cardiovascular diseases (CVD), including heart and pathological circulatory conditions, are the world's leading cause of mortality and morbidity. Endothelial dysfunction involved in CVD pathogenesis is a trigger, or consequence, of oxidative stress and inflammation. Endothelial dysfunction is defined as a diminished production/availability of nitric oxide, with or without an imbalance between endothelium-derived contracting, and relaxing factors associated with a pro-inflammatory and prothrombotic status. Endothelial dysfunction-induced phenotypic changes include up-regulated expression of adhesion molecules and increased chemokine secretion, leukocyte adherence, cell permeability, low-density lipoprotein oxidation, platelet activation, and vascular smooth muscle cell proliferation and migration. Inflammation-induced oxidative stress results in an increased accumulation of reactive oxygen species (ROS), mainly derived from mitochondria. Excessive ROS production causes oxidation of macromolecules inducing cell apoptosis mediated by cytochrome-c release. Oxidation of mitochondrial cardiolipin loosens cytochrome-c binding, thus, favoring its cytosolic release and activation of the apoptotic cascade. Oxidative stress increases vascular permeability, promotes leukocyte adhesion, and induces alterations in endothelial signal transduction and redox-regulated transcription factors. Identification of new endothelial dysfunction-related oxidative stress markers represents a research goal for better prevention and therapy of CVD. New-generation therapeutic approaches based on carriers, gene therapy, cardiolipin stabilizer, and enzyme inhibitors have proved useful in clinical practice to counteract endothelial dysfunction. Experimental studies are in continuous development to discover new personalized treatments. Gene regulatory mechanisms, implicated in endothelial dysfunction, represent potential new targets for developing drugs able to prevent and counteract CVD-related endothelial dysfunction. Nevertheless, many challenges remain to overcome before these technologies and personalized therapeutic strategies can be used in CVD management.

Elevated plasma tyrosine kinases VEGF-D and HER4 in heart failure patients decrease after heart transplantation in association with improved haemodynamics

Receptor tyrosine kinases (RTKs) are implicated in cardiovascular growth and remodelling. We aimed to identify the plasma levels of RTKs and related proteins and their association with haemodynamic alterations in heart failure (HF) and related pulmonary hypertension (PH) following heart transplantation (HT). Using proximity extension assay, 28 RTKs and related proteins were analysed in plasma from 20 healthy controls and 26 HF patients before and 1-year after HT. In end-stage HF, out of 28 RTKs, plasma vascular endothelial growth factor-D (VEGF-D) and human epidermal growth factor-4 (HER4) were elevated compared to controls (p < 0.001), but decreased (p < 0.0001) and normalised after HT. Following HT, plasma changes (Δ) of VEGF-D correlated with Δmean pulmonary artery pressure (rs = 0.65, p = 0.00049), Δpulmonary artery wedge pressure (rs = 0.72, p < 0.0001), Δpulmonary arterial compliance (PAC) (rs = - 0.52, p = 0.0083) and Δpulmonary vascular resistance (PVR) (rs = 0.58, p = 0.0032). ΔHER4 correlated with Δmean right atrial pressure (rs = 0.51, p = 0.012), ΔNT-proBNP (rs = 0.48, p = 0.016) and Δcardiac index (rs = - 0.56, p = 0.0044). In HF patients following HT, normalisation of VEGF-D reflected reversal of passive pulmonary congestion and restored PAC and PVR; whereas the normalisation of HER4 reflected decreased volume overload and improved cardiac function. The precise function of these proteins, their potential clinical use and pathophysiological relation in HF and related PH remain to be elucidated.

Formation and Growth of Cardiac Lymphatics during Embryonic Development, Heart Regeneration, and Disease

The lymphatic system plays crucial roles in regulating fluid homeostasis, immune surveillance, and lipid transport. As is in most of the body's organs, the heart possesses an extensive lymphatic network. Moreover, a robust lymphangiogenic response has been shown to take place following myocardial infarction, highlighting cardiac lymphatics as potential targets for therapeutic intervention. Yet, the unique molecular properties and functions of the heart's lymphatic system have only recently begun to be addressed. In this review, we discuss the mechanisms underlying the formation and growth of cardiac lymphatics during embryonic development and describe their characteristics across species. We further summarize recent findings highlighting diverse cellular origins for cardiac lymphatic endothelial cells and how they integrate to form a single functional lymphatic network. Finally, we outline novel therapeutic avenues aimed at enhancing lymphatic vessel formation and integrity following cardiac injury, which hold great promise for promoting healing of the infarcted heart.

Synthetic mRNA Encoding VEGF-A in Patients Undergoing Coronary Artery Bypass Grafting: Design of a Phase 2a Clinical Trial

Therapeutic angiogenesis may improve outcomes in patients with coronary artery disease undergoing surgical revascularization. Angiogenic factors may promote blood vessel growth and regenerate regions of ischemic but viable myocardium. Previous clinical trials of vascular endothelial growth factor A (VEGF-A) gene therapy with DNA or viral vectors demonstrated safety but not efficacy. AZD8601 is VEGF-A₁₆₅ mRNA formulated in biocompatible citrate-buffered saline and optimized for high-efficiency VEGF-A expression with minimal innate immune response. EPICCURE is an ongoing randomized, double-blind, placebo-controlled study of the safety of AZD8601 in patients with moderately decreased left ventricular function (ejection fraction 30%–50%) undergoing elective coronary artery bypass surgery. AZD8601 3 mg, 30 mg, or placebo is administered as 30 epicardial injections in a 10-min extension of cardioplegia. Injections are targeted to ischemic but viable myocardial regions in each patient using quantitative ¹⁵O-water positron emission tomography (PET) imaging (stress myocardial blood flow < 2.3 mL/g/min; resting myocardial blood flow > 0.6 mL/g/min). Improvement in regional and global myocardial blood flow quantified with ¹⁵O-water PET is an exploratory efficacy outcome, together with echocardiographic, clinical, functional, and biomarker measures. EPICCURE combines high-efficiency delivery with quantitative targeting and follow-up for robust assessment of the safety and exploratory efficacy of VEGF-A mRNA angiogenesis (ClinicalTrials.gov: NCT03370887).

Is gene therapy for limb ischemia a reality?

The concept of angiogenic therapy emerged in the early 1990s. The method employs genes that encode growth factors to promote formation of new vessels and remodeling of collateral vessels. Since the procedure involved in this therapy usually only consists of local injections of vectors, the process is minimally invasive, quick, and simple to perform. However, since the first clinical evidence of the effects of gene therapy with vascular endothelial growth factor (VEGF) was observed in patients with peripheral artery disease, to date only two angiogenic therapy drugs have been approved, one in Russia and another in Japan, which seem a very small number, in view of the large volume of investment made in pre-clinical and clinical studies. After all, can we conclude that angiogenic therapy is a reality?

Variability in Cardiac miRNA-122 Level Determines Therapeutic Potential of miRNA-Regulated AAV Vectors

Systemically delivered adeno-associated viral vector serotype 9 (AAV9) effectively transduces murine heart, but provides transgene expression also in liver and skeletal muscles. Improvement of the selectivity of transgene expression can be achieved through incorporation of target sites (TSs) for miRNA-122 and miRNA-206 into the 3′ untranslated region (3′ UTR) of the expression cassette. Here, we aimed to generate such miRNA-122- and miRNA-206-regulated AAV9 vector for a therapeutic, heart-specific overexpression of heme oxygenase-1 (HO-1). We successfully validated the vector functionality in murine cell lines corresponding to tissues targeted by AAV9. Next, we evaluated biodistribution of transgene expression following systemic vector delivery to HO-1-deficient mice of mixed C57BL/6J × FVB genetic background. Although AAV genomes were present in the hearts of these animals, HO-1 protein expression was either absent or significantly impaired. We found that miRNA-122, earlier described as liver specific, was present also in the hearts of C57BL/6J × FVB mice. Various levels of miRNA-122 expression were observed in the hearts of other mouse strains, in heart tissues of patients with cardiomyopathy, and in human induced pluripotent stem cell-derived cardiomyocytes in which we also confirmed such posttranscriptional regulation of transgene expression. Our data clearly indicate that therapeutic utilization of miRNA-based regulation strategy needs to consider inter-individual variability.

Gene Therapy for the Heart Lessons Learned and Future Perspectives

While clinical gene therapy celebrates its first successes, with several products already approved for clinical use and several hundreds in the final stages of the clinical approval pipeline, there is not a single gene therapy approach that has worked for the heart. Here, we review the past experience gained in the several cardiac gene therapy clinical trials that had the goal of inducing therapeutic angiogenesis in the ischemic heart and in the attempts at modulating cardiac function in heart failure. Critical assessment of the results so far achieved indicates that the efficiency of cardiac gene delivery remains a major hurdle preventing success but also that improvements need to be sought in establishing more reliable large animal models, choosing more effective therapeutic genes, better designing clinical trials, and more deeply understanding cardiac biology. We also emphasize a few areas of cardiac gene therapy development that hold great promise for the future. In particular, the transition from gene addition studies using protein-coding cDNAs to the modulation of gene expression using small RNA therapeutics and the improvement of precise gene editing now pave the way to applications such as cardiac regeneration after myocardial infarction and gene correction for inherited cardiomyopathies that were unapproachable until a decade ago.

Distinct Characteristics of VEGF-D and VEGF-C to Predict Mortality in Patients With Suspected or Known Coronary Artery Disease

Background

VEGF‐D (vascular endothelial growth factor D) and VEGF‐C are secreted glycoproteins that can induce lymphangiogenesis and angiogenesis. They exhibit structural homology but have differential receptor binding and regulatory mechanisms. We recently demonstrated that the serum VEGF‐C level is inversely and independently associated with all‐cause mortality in patients with suspected or known coronary artery disease. We investigated whether VEGF‐D had distinct relationships with mortality and cardiovascular events in those patients.

Methods and Results

We performed a multicenter, prospective cohort study of 2418 patients with suspected or known coronary artery disease undergoing elective coronary angiography. The serum level of VEGF‐D was measured. The primary outcome was all‐cause death. The secondary outcomes were cardiovascular death and major adverse cardiovascular events defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke. During the 3‐year follow‐up, 254 patients died from any cause, 88 died from cardiovascular disease, and 165 developed major adverse cardiovascular events. After adjustment for possible clinical confounders, cardiovascular biomarkers (N‐terminal pro‐B‐type natriuretic peptide, cardiac troponin‐I, and high‐sensitivity C‐reactive protein), and VEGF‐C, the VEGF‐D level was significantly associated with all‐cause death and cardiovascular death but not with major adverse cardiovascular events.. Moreover, the addition of VEGF‐D, either alone or in combination with VEGF‐C, to the model with possible clinical confounders and cardiovascular biomarkers significantly improved the prediction of all‐cause death but not that of cardiovascular death or major adverse cardiovascular events. Consistent results were observed within patients over 75 years old.

Conclusions

In patients with suspected or known coronary artery disease undergoing elective coronary angiography, an elevated VEGF‐D value seems to independently predict all‐cause mortality.

Adenoviral Gene Transfer of Gremlin Modulates Vascular Endothelial Growth Factor-A-Induced Angiogenesis in Porcine Myocardium

Coronary artery disease is a major cause of death and disability worldwide. New therapies are needed for patients who do not benefit or are not suitable for current treatments. Angiogenic gene therapy using vascular endothelial growth factors (VEGFs) has shown potential in preclinical trials. However, undesired side effects, such as increased permeability, limit their therapeutic potential. The aim of this study was to investigate if adenoviral gene transfer of a VEGF receptor 2 (VEGFR-2) ligand Gremlin, given simultaneously with VEGF-A, could modulate VEGFR-2-mediated increase in permeability without impairing the angiogenic effect of VEGF-A gene therapy. Gene transfers were done in pigs (n = 22) using endocardial injections with an endovascular injection catheter. Animals were divided in three groups receiving adenoviral (Ad) VEGF-A (n = 10), Gremlin (n = 6), or VEGF-A+Gremlin (n = 6) gene therapy. Animals were sacrificed and samples collected 6 days later for histological, safety, and permeability analyses. The mean capillary area was significantly increased in both treatment groups with AdVEGF-A when compared with the AdGremlin group. Also, the capillary area was significantly larger in AdVEGF-A group without AdGremlin. No significant differences in tissue permeability were observed using modified Miles assay between AdVEGF-A and AdVEGF-A+AdGremlin groups. However, cardiac tamponade and sudden cardiac deaths were observed only in the AdVEGF-A group. AdVEGF-A induces strong angiogenesis in porcine myocardium. Our results suggest that AdGremlin can limit the side effects of AdVEGF-A therapy, even though no direct effect on tissue permeability could be demonstrated. This could enable the use of larger AdVEGF-A doses to increase the treatment area and angiogenic effects without adverse side effects.

Therapeutic vascularization in regenerative medicine

Therapeutic angiogenesis, that is, the generation of new vessels by delivery of specific factors, is required both for rapid vascularization of tissue‐engineered constructs and to treat ischemic conditions. Vascular endothelial growth factor (VEGF) is the master regulator of angiogenesis. However, uncontrolled expression can lead to aberrant vascular growth and vascular tumors (angiomas). Major challenges to fully exploit VEGF potency for therapy include the need to precisely control in vivo distribution of growth factor dose and duration of expression. In fact, the therapeutic window of VEGF delivery depends on its amount in the microenvironment around each producing cell rather than on the total dose, since VEGF remains tightly bound to extracellular matrix (ECM). On the other hand, short‐term expression of less than about 4 weeks leads to unstable vessels, which promptly regress following cessation of the angiogenic stimulus. Here, we will briefly overview some key aspects of the biology of VEGF and angiogenesis and discuss their therapeutic implications with a particular focus on approaches using gene therapy, genetically modified progenitors, and ECM engineering with recombinant factors. Lastly, we will present recent insights into the mechanisms that regulate vessel stabilization and the switch between normal and aberrant vascular growth after VEGF delivery, to identify novel molecular targets that may improve both safety and efficacy of therapeutic angiogenesis.

Useful applications of growth factors for cardiovascular regenerative medicine

Novel advances for cardiovascular diseases (CVDs) include regenerative approaches for fibrosis, hypertrophy, and neoangiogenesis. Studies indicate that growth factor (GF) signaling could promote heart repair since most of the evidence is derived from preclinical models. Observational studies have evaluated GF serum/plasma levels as feasible biomarkers for risk stratification of CVDs. Noteworthy, two clinical interventional published studies showed that the administration of growth factors (GFs) induced beneficial effect on left ventricular ejection fraction (LVEF), myocardial perfusion, end-systolic volume index (ESVI). To date, large scale ongoing studies are in Phase I-II and mostly focussed on intramyocardial (IM), intracoronary (IC) or intravenous (IV) administration of vascular endothelial growth factor (VEGF) and fibroblast growth factor-23 (FGF-23) which result in the most investigated GFs in the last 10 years. Future data of ongoing randomized controlled studies will be crucial in understanding whether GF-based protocols could be in a concrete way effective in the clinical setting.

Perspectives on Directions and Priorities for Future Preclinical Studies in Regenerative Medicine

The myocardium consists of numerous cell types embedded in organized layers of ECM (extracellular matrix) and requires an intricate network of blood and lymphatic vessels and nerves to provide nutrients and electrical coupling to the cells. Although much of the focus has been on cardiomyocytes, these cells make up <40% of cells within a healthy adult heart. Therefore, repairing or regenerating cardiac tissue by merely reconstituting cardiomyocytes is a simplistic and ineffective approach. In fact, when an injury occurs, cardiac tissue organization is disrupted at the level of the cells, the tissue architecture, and the coordinated interaction among the cells. Thus, reconstitution of a functional tissue must reestablish electrical and mechanical communication between cardiomyocytes and restore their surrounding environment. It is also essential to restore distinctive myocardial features, such as vascular patency and pump function. In this article, we review the current status, challenges, and future priorities in cardiac regenerative or reparative medicine. In the first part, we provide an overview of our current understanding of heart repair and comment on the main contributors and mechanisms involved in innate regeneration. A brief section is dedicated to the novel concept of rejuvenation or regeneration, which we think may impact future development in the field. The last section describes regenerative therapies, where the most advanced and disruptive strategies used for myocardial repair are discussed. Our recommendations for priority areas in studies of cardiac regeneration or repair are summarized in Tables 1 and 2 .

Cardiac lymphatics in health and disease

The lymphatic vasculature, which accompanies the blood vasculature in most organs, is indispensable in the maintenance of tissue fluid homeostasis, immune cell trafficking, and nutritional lipid uptake and transport, as well as in reverse cholesterol transport. In this Review, we discuss the physiological role of the lymphatic system in the heart in the maintenance of cardiac health and describe alterations in lymphatic structure and function that occur in cardiovascular pathology, including atherosclerosis and myocardial infarction. We also briefly discuss the role that immune cells might have in the regulation of lymphatic growth (lymphangiogenesis) and function. Finally, we provide examples of how the cardiac lymphatics can be targeted therapeutically to restore lymphatic drainage in the heart to limit myocardial oedema and chronic inflammation.

Long-term follow-up and safety assessment of angiogenic gene therapy trial VIF-CAD: Transcatheter intramyocardial administration of a bicistronic plasmid expressing VEGF-A165/bFGF cDNA for the treatment of refractory coronary artery disease

There have been a number of angiogenic gene therapy trials, yielding mixed results as to efficacy, but demonstrating uniform short-term treatment safety. Data regarding long-term safety of angiogenic gene therapy are limited. Double-blind VIF-CAD trial (NCT00620217) assessed myocardial perfusion and clinical data in 52 refractory coronary artery disease (CAD) patients randomized into treatment (VIF; n = 33) and Placebo (n = 19) arms. VIF group received electromechanical system NOGA-guided intramyocardial injections of VEGF-A165/bFGF plasmid (VIF) into ischemic regions, while the Placebo group-placebo plasmid injections. Full 1-year follow-up data have been published. This study presents the results of over 10-year (median 133 months, range 95-149) safety follow-up of VIF-CAD patients. Overall, 12 (36.4%) patients died in VIF and 8 (42.1%) in Placebo group (P = .68). Cardiovascular mortality was 12/33 (36.4%) in the VIF group and 6/19 (31.6%) in Placebo group (P = .73). Two Placebo patients died due to malignancies, but no VIF patients (P = .17). The Kaplan-Meier curves of combined endpoint: cardiovascular mortality, myocardial infarction and stroke were similar for both patient groups (P = .71). Odds ratio of Placebo group increasing (reaching a worse) their CCS class versus VIF was non-significant (OR 1.28, 95% CI = 0.66-2.45; P = .47). However, CCS class improved in time irrespectively of treatment-OR of reaching a less favorable CCS class per each year of follow-up was 0.74 (95% CI 0.685-0.792; P < .0001, pooled data). There were no differences in readmission rates. Intramyocardial VEGF-A165/bFGF plasmid administration appears safe, with no evidence of an increase in the incidence of death, malignancy, myocardial infarction or stroke during 10-year follow-up in this limited patient population.

Deletion of Lymphangiogenic and Angiogenic Growth Factor VEGF-D Leads to Severe Hyperlipidemia and Delayed Clearance of Chylomicron Remnants

Objective- Dyslipidemia is one of the key factors behind coronary heart disease. Blood and lymphatic vessels play pivotal roles in both lipoprotein metabolism and development of atherosclerotic plaques. Recent studies have linked members of VEGF (vascular endothelial growth factor) family to lipid metabolism, but the function of VEGF-D has remained unexplored. Here, we investigated how the deletion of VEGF-D affects lipid and lipoprotein metabolism in atherogenic LDLR^-/- ApoB^100/100 mice. Approach and Results- Deletion of VEGF-D (VEGF-D^-/-LDLR^-/-ApoB^100/100) led to markedly elevated plasma cholesterol and triglyceride levels without an increase in atherogenesis. Size distribution and hepatic lipid uptake studies confirmed a delayed clearance of large chylomicron remnant particles that cannot easily penetrate through the vascular endothelium. Mechanistically, the inhibition of VEGF-D signaling significantly decreased the hepatic expression of SDC1 (syndecan 1), which is one of the main receptors for chylomicron remnant uptake when LDLR is absent. Immunohistochemical staining confirmed reduced expression of SDC1 in the sinusoidal surface of hepatocytes in VEGF-D deficient mice. Furthermore, hepatic RNA-sequencing revealed that VEGF-D is also an important regulator of genes related to lipid metabolism and inflammation. The lack of VEGF-D signaling via VEGFR3 (VEGF receptor 3) led to lowered expression of genes regulating triglyceride and cholesterol production, as well as downregulation of peroxisomal β-oxidation pathway. Conclusions- These results demonstrate that VEGF-D, a powerful lymphangiogenic and angiogenic growth factor, is also a major regulator of chylomicron metabolism in mice.

New opportunities for targeting redox dysregulation in cardiovascular disease

Despite substantial promise, the use of antioxidant therapy to improve cardiovascular outcomes has been disappointing. Whilst the fundamental biology supporting their use continues to build, the challenge now is to differentially target dysregulated redox signalling domains and to identify new ways to deliver antioxidant substances. Looking further afield to other disciplines, there is an emerging ‘tool-kit’ containing sophisticated molecular and drug delivery applications. Applying these to the cardiovascular redox field could prove a successful strategy to combat the increasing disease burden. Excessive reactive oxygen species production and protein modifications in the mitochondria has been the target of successful drug development with several positive outcomes emerging in the cardiovascular space, harnessing both improved delivery mechanisms and enhanced understanding of the biological abnormalities. Using this as a blueprint, similar strategies could be applied and expanded upon in other redox-hot-spots, such as the caveolae sub-cellular region, which houses many of the key cardiovascular redox proteins such as NADPH oxidase, endothelial nitric oxide synthase, angiotensin II receptors, and beta adrenoceptors. The expanded tool kit of drug development, including gene and miRNA therapies, nanoparticle technology and micropeptide targeting, can be applied to target dysregulated redox signalling in subcellular compartments of cardiovascular cells. In this review, we consider the opportunities for improving cardiovascular outcomes by utilizing new technology platforms to target subcellular ‘bonfires’ generated by dysregulated redox pathways, to improve clinical outcomes.

NHLBI Working Group Recommendations to Reduce Lipoprotein(a)-Mediated Risk of Cardiovascular Disease and Aortic Stenosis

Pathophysiological, epidemiological, and genetic studies provide strong evidence that lipoprotein(a) [Lp(a)] is a causal mediator of cardiovascular disease (CVD) and calcific aortic valve disease (CAVD). Specific therapies to address Lp(a)-mediated CVD and CAVD are in clinical development. Due to knowledge gaps, the National Heart, Lung, and Blood Institute organized a working group that identified challenges in fully understanding the role of Lp(a) in CVD/CAVD. These included the lack of research funding, inadequate experimental models, lack of globally standardized Lp(a) assays, and inadequate understanding of the mechanisms underlying current drug therapies on Lp(a) levels. Specific recommendations were provided to facilitate basic, mechanistic, preclinical, and clinical research on Lp(a); foster collaborative research and resource sharing; leverage expertise of different groups and centers with complementary skills; and use existing National Heart, Lung, and Blood Institute resources. Concerted efforts to understand Lp(a) pathophysiology, together with diagnostic and therapeutic advances, are required to reduce Lp(a)-mediated risk of CVD and CAVD.

Lymphatic and blood systems: Identical or fraternal twins?

Blood and lymphatic systems work in close collaboration to ensure their respective physiological functions. The lymphatic vessel network is being extensively studied, but has been overlooked as compared to the blood vasculature mainly due to the problematic discrimination of lymphatic vessels from the blood ones. This issue has been fortunately resolved in the past decade leading to the emergence of a huge amount of data in lymphatic biology revealing many shared features with the blood vasculature. However, this likeliness between the two vascular systems may lead to a simplistic view of lymphatics and a direct transcription of what is known for the blood system to the lymphatic one, thereby neglecting the lymphatic specificities. In this context, this review aims to clarify the main differences between the two vascular systems focusing on recently discovered lymphatic features.

Lymphatic system identification, pathophysiology and therapy in the cardiovascular diseases

The mammalian circulatory system comprises both the cardiovascular system and the lymphatic system. In contrast to the closed, high-pressure and circular blood vascular circulation, the lymphatic system forms an open, low-pressure and unidirectional transit network from the extracellular space to the venous system. It plays a key role in regulating tissue fluid homeostasis, absorption of gastrointestinal lipids, and immune surveillance throughout the body. Despite the critical physiological functions of the lymphatic system, a complete understanding of the lymphatic vessels lags far behind that of the blood vasculatures due to the challenge of their visualization. During the last 20 years, discoveries of underlying genes responsible for lymphatic vessel biology, combined with state-of-the-art lymphatic function imaging and quantification techniques, have established the importance of the lymphatic vasculature in the pathogenesis of cardiovascular diseases including lymphedema, obesity and metabolic diseases, dyslipidemia, hypertension, inflammation, atherosclerosis and myocardial infraction. In this review, we highlight the most recent advances in the field of lymphatic vessel biology, with an emphasis on the new identification techniques of lymphatic system, pathophysiological mechanisms of atherosclerosis and myocardial infarction, and new therapeutic perspectives of lymphangiogenesis.

Cardiac revascularization: state of the art and perspectives

Cardiac ischemia is the leading cause of morbidity and mortality in a worldwide epidemic. The progressive understanding of the mechanisms driving new blood vessel formation has led to numerous attempts to revascularize the ischemic heart in animal models and in humans. Here, we provide an overview of the current state of the art and discuss the major obstacles that have so far limited the clinical success of cardiac revascularization.

Therapeutic vascular growth in the heart

Despite tremendous efforts in preclinical research over the last decades, the clinical translation of therapeutic angiogenesis to grow stable and functional blood vessels in patients with ischemic diseases continues to prove challenging. In this mini review, we briefly present the current main approaches applied to improve pro-angiogenic therapies. Specific examples from research on therapeutic cardiac angiogenesis and arteriogenesis will be discussed, and finally some suggestions for future therapeutic developments will be presented.

Molecular discoveries and treatment strategies by direct reprogramming in cardiac regeneration

Cardiac tissue has minimal endogenous regenerative capacity in response to injury. Treatment options are limited following tissue damage after events such as myocardial infarction. Current strategies are aimed primarily at injury prevention, but attention has been increasingly targeted toward the development of regenerative therapies. This review focuses on recent developments in the field of cardiac fibroblast reprogramming into induced cardiomyocytes. Early efforts to produce cardiac regeneration centered around induced pluripotent stem cells, but clinical translation has proved elusive. Currently, techniques are being developed to directly transdifferentiate cardiac fibroblasts into induced cardiomyocytes. Viral vector-driven expression of a combination of transcription factors including Gata4, Mef2c, and Tbx5 induced cardiomyocyte development in mice. Subsequent combinational modifications have extended these results to human cell lines and increased efficacy. The miRNAs including combinations of miR-1, miR-133, miR-208, and miR-499 can improve or independently drive regeneration of cardiomyocytes. Similar results could be obtained by combinations of small molecules with or without transcription factor or miRNA expression. The local tissue environment greatly impacts favorability for reprogramming. Modulation of signaling pathways, especially those mediated by VEGF and TGF-β, enhance differentiation to cardiomyocytes. Current reprogramming strategies are not ready for clinical application, but recent breakthroughs promise regenerative cardiac therapies in the near future.

Downregulation of VEGFR3 signaling alters cardiac lymphatic vessel organization and leads to a higher mortality after acute myocardial infarction

Heart has a wide lymphatic network but the importance of cardiac lymphatic system in heart diseases has remained unclear. Vascular Endothelial Growth Factor Receptor 3 (VEGFR3) is a key molecule in the development and maintenance of cardiac lymphatic vessels. Here we characterized the role of VEGFR3 in healthy hearts and after myocardial infarction (MI) by using sVEGFR3 transgenic mice expressing a soluble decoy VEGFR3 under K14 promoter and Chy mice which have an inactivating mutation in the VEGFR3 gene. Cardiac lymphatic vessels were significantly dilated in the healthy hearts of sVEGFR3 mice when compared to controls. Lymphatic vessels formed large sheet-like structures in Chy mice. Attenuated VEGFR3 signaling led to a more severe MI predisposing to a significantly higher mortality in sVEGFR3 mice than in control mice. sVEGFR3 mice displayed intramyocardial hemorrhages in the infarcted area indicating hyperpermeability of the vasculature. Furthermore, novel MRI methods TRAFF2 and TRAFF4 and histological analysis revealed a modified structure of the fibrotic infarcted area in sVEGFR3 mice. In conclusion, the downregulation of VEGFR3 signaling modifies the structure of cardiac lymphatic network and causes vascular leakiness and increased mortality after MI.

Angiogenic lncRNAs: A potential therapeutic target for ischaemic heart disease

Long noncoding RNAs (LncRNAs) are involved in biological processes and the pathology of diseases and represent an important biomarker or therapeutic target for disease. Emerging evidence has suggested that lncRNAs modulate angiogenesis by regulating the angiogenic cell process-including vascular endothelial cells (VECs); stem cells, particularly bone marrow-derived stem cells, endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs); and vascular smooth muscle cells (VSMCs)-and participating in ischaemic heart disease (IHD). Therapeutic angiogenesis as an alternative therapy to promote coronary collateral circulation has been demonstrated to significantly improve the prognosis and quality of life of patients with IHD in past decades. Therefore, lncRNAs are likely to represent a novel therapeutic target for IHD through regulation of the angiogenesis process. This review summarizes the classification and functions of lncRNAs and their roles in regulating angiogenesis and in IHD, in the context of an overview of therapeutic angiogenesis in clinical trials.

Future directions for therapeutic strategies in post-ischaemic vascularization: a position paper from European Society of Cardiology Working Group on Atherosclerosis and Vascular Biology

Modulation of vessel growth holds great promise for treatment of cardiovascular disease. Strategies to promote vascularization can potentially restore function in ischaemic tissues. On the other hand, plaque neovascularization has been shown to associate with vulnerable plaque phenotypes and adverse events. The current lack of clinical success in regulating vascularization illustrates the complexity of the vascularization process, which involves a delicate balance between pro- and anti-angiogenic regulators and effectors. This is compounded by limitations in the models used to study vascularization that do not reflect the eventual clinical target population. Nevertheless, there is a large body of evidence that validate the importance of angiogenesis as a therapeutic concept. The overall aim of this Position Paper of the ESC Working Group of Atherosclerosis and Vascular biology is to provide guidance for the next steps to be taken from pre-clinical studies on vascularization towards clinical application. To this end, the current state of knowledge in terms of therapeutic strategies for targeting vascularization in post-ischaemic disease is reviewed and discussed. A consensus statement is provided on how to optimize vascularization studies for the identification of suitable targets, the use of animal models of disease, and the analysis of novel delivery methods.

Lipoprotein Apheresis Acutely Reverses Coronary Microvascular Dysfunction in Patients With Severe Hypercholesterolemia

OBJECTIVES

This study evaluated whether lipoprotein apheresis produces immediate changes in resting perfusion in subjects with severe hypercholesterolemia, and whether there is a difference in the response between peripheral and coronary microcirculations.

BACKGROUND

Lipoprotein apheresis is used in patients with severe hypercholesterolemia to reduce plasma levels of low-density lipoprotein cholesterol.

METHODS

Quantitative contrast-enhanced ultrasound perfusion imaging of the myocardium at rest and skeletal muscle at rest and during calibrated contractile exercise was performed before and immediately after lipoprotein apheresis in 8 subjects with severe hypercholesterolemia, 7 of whom had a diagnosis of familial hypercholesterolemia. Myocardial perfusion imaging was also performed in 14 normal control subjects. Changes in myocardial work and left ventricular function were assessed by echocardiography. Ex vivo ovine coronary and femoral artery ring tension assays were assessed in the presence of pre- and post-apheresis plasma.

RESULTS

Apheresis acutely decreased low-density lipoprotein cholesterol (234.9 ± 103.2 mg/dl vs. 67.1 ± 49.5 mg/dl; p < 0.01) and oxidized phospholipid on apolipoprotein B-100 (60.2 ± 55.2 nmol/l vs. 47.0 ± 24.5 nmol/l; p = 0.01), and acutely increased resting myocardial perfusion (55.1 [95% confidence interval: 77.2 to 73.1] IU/s vs. 135 [95% confidence interval: 81.2 to 189.6] IU/s; p = 0.01), without changes in myocardial work. Myocardial longitudinal strain improved in those subjects with reduced pre-apheresis function. Skeletal muscle perfusion at rest and during contractile exercise was unchanged by apheresis. Acetylcholine-mediated dilation of ex vivo ovine coronary but not femoral arteries was impaired in pre-apheresis plasma and was completely reversed in post-apheresis plasma.

CONCLUSIONS

Lipoprotein apheresis produces an immediate improvement in coronary microvascular function, which increases myocardial perfusion and normalizes endothelial-dependent vasodilation. These changes are not observed in the periphery. (Acute Microvascular Changes With LDL Apheresis; NCT02388633).