Paracrine secretions seem to mediate therapeutic effects of human CD34
stem cells locally transplanted in patients with myocardial and critical limb ischemia and in animal models. Earlier, we had ...discovered that paracrine secretion from human CD34
cells contains proangiogenic, membrane-bound nanovesicles called exosomes (CD34Exo).
Here, we investigated the mechanisms of CD34Exo-mediated ischemic tissue repair and therapeutic angiogenesis by studying their miRNA content and uptake.
When injected into mouse ischemic hindlimb tissue, CD34Exo, but not the CD34Exo-depleted conditioned media, mimicked the beneficial activity of their parent cells by improving ischemic limb perfusion, capillary density, motor function, and their amputation. CD34Exo were found to be enriched with proangiogenic miRNAs such as miR-126-3p. Knocking down miR-126-3p from CD34Exo abolished their angiogenic activity and beneficial function both in vitro and in vivo. Interestingly, injection of CD34Exo increased miR-126-3p levels in mouse ischemic limb but did not affect the endogenous synthesis of miR-126-3p, suggesting a direct transfer of stable and functional exosomal miR-126-3p. miR-126-3p enhanced angiogenesis by suppressing the expression of its known target,
, simultaneously modulating the expression of genes involved in angiogenic pathways such as
(vascular endothelial growth factor),
(angiopoietin 1),
(angiopoietin 2), MMP9 (matrix metallopeptidase 9),
(thrombospondin 1), etc. Interestingly, CD34Exo, when treated to ischemic hindlimbs, were most efficiently internalized by endothelial cells relative to smooth muscle cells and fibroblasts, demonstrating a direct role of stem cell-derived exosomes on mouse endothelium at the cellular level.
Collectively, our results have demonstrated a novel mechanism by which cell-free CD34Exo mediates ischemic tissue repair via beneficial angiogenesis. Exosome-shuttled proangiogenic miRNAs may signify amplification of stem cell function and may explain the angiogenic and therapeutic benefits associated with CD34
stem cell therapy.
Cardiomyocyte function depends on coordinated movements of calcium into and out of the cell and the proper delivery of ATP to energy-utilizing enzymes. Defects in calcium-handling proteins and ...abnormal energy metabolism are features of heart failure. Recent discoveries have led to gene-based therapies targeting calcium-transporting or -binding proteins, such as the cardiac sarco(endo)plasmic reticulum calcium ATPase (SERCA2a), leading to improvements in calcium homeostasis and excitation-contraction coupling. Here we review impaired calcium cycling and energetics in heart failure, assessing their roles from both a mutually exclusive and interdependent viewpoint, and discuss therapies that may improve the failing myocardium.
Calcium handling and energy metabolism are defective in the failing myocardium. In this Perspective, Gorski et al. review the various molecular mechanisms underlying impaired calcium cycling and abnormal energetics in the heart and discuss current and potential gene therapies for the treatment of heart failure.
Human Cardiac Gene Therapy Ishikawa, Kiyotake; Weber, Thomas; Hajjar, Roger J
Circulation research,
2018-August-17, Volume:
123, Issue:
5
Journal Article
Peer reviewed
Open access
In the past 10 years, there has been tremendous progress made in the field of gene therapy. Effective treatments of Leber congenital amaurosis, hemophilia, and spinal muscular atrophy have been ...largely based on the efficiency and safety of adeno-associated vectors. Myocardial gene therapy has been tested in patients with heart failure using adeno-associated vectors with no safety concerns but lacking clinical improvements. Cardiac gene therapy is adapting to the new developments in vectors, delivery systems, targets, and clinical end points and is poised for success in the near future.
Empagliflozin cardiac benefits in the EMPA-REG OUTCOME (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients) trial cannot be explained exclusively by its ...antihyperglycemic activity.
The hypothesis was that empagliflozin’s cardiac benefits are mediated by switching myocardial fuel metabolism away from glucose toward ketone bodies (KB), which improves myocardial energy production.
Heart failure was induced in nondiabetic pigs (n = 14) by 2-h balloon occlusion of the proximal left anterior descending artery. Animals were randomized to empagliflozin or placebo for 2 months. Animals were evaluated with cardiac magnetic resonance imaging and 3-dimensional echocardiography. Myocardial metabolite consumption was analyzed by simultaneous blood sampling from coronary artery and coronary sinus. Myocardial samples were obtained for molecular evaluation. Nonmyocardial infarction animals served as comparison.
Despite similar initial ischemic myocardial injury in both groups, the empagliflozin group showed amelioration of adverse remodeling at 2 months (lower left ventricular LV mass, reduced LV dilatation, less LV sphericity) versus the control group. LV systolic function (LV ejection fraction and echocardiography-derived strains) was improved, as was neurohormonal activation. Compared with nonmyocardial infarction, control animals increased myocardial glucose consumption mainly through anaerobic glycolysis while reducing utilization of free fatty acid (FFA) and branched-chain amino acid (BCAA). Empagliflozin-treated pigs did not consume glucose (reduction in myocardial glucose uptake, and glucose-related enzymes) but instead switched toward utilization of KB, FFA, and BCAA (increased myocardial uptake of these 3 metabolites, and enhanced expression/activity of the enzymes implicated in the metabolism of KB/FFA/BCAA). Empagliflozin increased myocardial ATP content and enhanced myocardial work efficiency.
Empagliflozin ameliorates adverse cardiac remodeling and heart failure in a nondiabetic porcine model. Empagliflozin switches myocardial fuel utilization away from glucose toward KB, FFA, and BCAA, thereby improving myocardial energetics, enhancing LV systolic function, and ameliorating adverse LV remodeling.
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Advances in understanding the molecular basis of myocardial dysfunction, together with the evolution of increasingly efficient gene transfer technology, make gene-based therapy a promising treatment ...option for heart conditions. Cardiovascular gene therapy has benefitted from recent advancements in vector technology, design, and delivery modalities. There is a critical need to explore new therapeutic approaches in heart failure, and gene therapy has emerged as a viable alternative. Advances in understanding of the molecular basis of myocardial dysfunction, together with the development of increasingly efficient gene transfer technology, has placed heart failure within reach of gene-based therapy. The recent successful and safe completion of a phase 2 trial targeting the cardiac sarcoplasmic/endoplasmic reticulum Ca2+ ATPase pump (SERCA2a) has the potential to open a new era for gene therapy for heart failure.
Gene therapy has emerged as a powerful tool in targeting the molecular mechanisms implicated in heart failure. Refinements in vector technology, including the development of recombinant ...adeno-associated vectors, have allowed for safe, long-term, and efficient gene transfer to the myocardium. These advancements, coupled with evolving delivery techniques, have placed gene therapy as a viable therapeutic option for patients with heart failure. However, after much promise in early-phase clinical trials, the more recent larger clinical trials have shown disappointing results, thus forcing the field to re-evaluate current vectors, delivery systems, targets, and endpoints. We provide here an updated review of current cardiac gene therapy programmes that have been or are being translated into clinical trials.
Cardiac myocyte function is dependent on the synchronized movements of Ca(2+) into and out of the cell, as well as between the cytosol and sarcoplasmic reticulum. These movements determine cardiac ...rhythm and regulate excitation-contraction coupling. Ca(2+) cycling is mediated by a number of critical Ca(2+)-handling proteins and transporters, such as L-type Ca(2+) channels (LTCCs) and sodium/calcium exchangers in the sarcolemma, and sarcoplasmic/endoplasmic reticulum calcium ATPase 2a (SERCA2a), ryanodine receptors, and cardiac phospholamban in the sarcoplasmic reticulum. The entry of Ca(2+) into the cytosol through LTCCs activates the release of Ca(2+) from the sarcoplasmic reticulum through ryanodine receptor channels and initiates myocyte contraction, whereas SERCA2a and cardiac phospholamban have a key role in sarcoplasmic reticulum Ca(2+) sequesteration and myocyte relaxation. Excitation-contraction coupling is regulated by phosphorylation of Ca(2+)-handling proteins. Abnormalities in sarcoplasmic reticulum Ca(2+) cycling are hallmarks of heart failure and contribute to the pathophysiology and progression of this disease. Correcting impaired intracellular Ca(2+) cycling is a promising new approach for the treatment of heart failure. Novel therapeutic strategies that enhance myocyte Ca(2+) homeostasis could prevent and reverse adverse cardiac remodeling and improve clinical outcomes in patients with heart failure.
The adult mammalian heart has limited regenerative capacity, mostly attributable to postnatal cardiomyocyte cell cycle arrest. In the last 2 decades, numerous studies have explored cardiomyocyte cell ...cycle regulatory mechanisms to enhance myocardial regeneration after myocardial infarction. Pkm2 (Pyruvate kinase muscle isoenzyme 2) is an isoenzyme of the glycolytic enzyme pyruvate kinase. The role of Pkm2 in cardiomyocyte proliferation, heart development, and cardiac regeneration is unknown.
We investigated the effect of Pkm2 in cardiomyocytes through models of loss (cardiomyocyte-specific Pkm2 deletion during cardiac development) or gain using cardiomyocyte-specific Pkm2 modified mRNA to evaluate Pkm2 function and regenerative affects after acute or chronic myocardial infarction in mice.
Here, we identify Pkm2 as an important regulator of the cardiomyocyte cell cycle. We show that Pkm2 is expressed in cardiomyocytes during development and immediately after birth but not during adulthood. Loss of function studies show that cardiomyocyte-specific Pkm2 deletion during cardiac development resulted in significantly reduced cardiomyocyte cell cycle, cardiomyocyte numbers, and myocardial size. In addition, using cardiomyocyte-specific Pkm2 modified RNA, our novel cardiomyocyte-targeted strategy, after acute or chronic myocardial infarction, resulted in increased cardiomyocyte cell division, enhanced cardiac function, and improved long-term survival. We mechanistically show that Pkm2 regulates the cardiomyocyte cell cycle and reduces oxidative stress damage through anabolic pathways and β-catenin.
We demonstrate that Pkm2 is an important intrinsic regulator of the cardiomyocyte cell cycle and oxidative stress, and highlight its therapeutic potential using cardiomyocyte-specific Pkm2 modified RNA as a gene delivery platform.
The Calcium Up-Regulation by Percutaneous Administration of Gene Therapy In Cardiac Disease (CUPID 1) study was a phase 1/phase 2 first-in-human clinical gene therapy trial using an adeno-associated ...virus serotype 1 (AAV1) vector carrying the sarcoplasmic reticulum calcium ATPase gene (AAV1/SERCA2a) in patients with advanced heart failure. The study explored potential benefits of the therapy at 12 months, and results were previously reported.
To report long-term (3-year) clinical effects and transgene expression in the patients in CUPID 1.
A total of 39 patients with advanced heart failure who were on stable, optimal heart failure therapy were randomized to receive intracoronary infusion of AAV1/SERCA2a in 1 of 3 doses (low-dose, 6×10(11) DNase-resistant particles; mid-dose, 3×10(12) DNase-resistant particles; and high-dose, 1×10(13) DNase-resistant particles) versus placebo. The following recurrent cardiovascular and terminal events were tracked for 3 years in all groups: myocardial infarction, worsening heart failure, heart failure-related hospitalization, ventricular assist device placement, cardiac transplantation, and death. The number of cardiovascular events, including death, was highest in the placebo group, high but delayed in the low- and mid-dose groups, and lowest in the high-dose group. Evidence of long-term transgene presence was also observed in high-dose patients. The risk of prespecified recurrent cardiovascular events was reduced by 82% in the high-dose versus placebo group (P=0.048). No safety concerns were noted during the 3-year follow-up.
After a single intracoronary infusion of AAV1/SERCA2a in patients with advanced heart failure, positive signals of cardiovascular events persist for years.
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