Implementing Precision Medicine for Dilated Cardiomyopathy: Insights from The DCM Consortium.

Background: Clinical genetic evaluation of dilated cardiomyopathy (DCM) is implemented variably or not at all. Identifying needs and barriers to genetic evaluations will enable strategies to enhance precision medicine care.

Methods: An online survey was conducted in June 2024 among cardiologist investigators of the DCM Consortium from US advanced heart failure/transplant (HF/TX) programs to collect demographics, training, program characteristics, genetic evaluation practices for DCM, and implementation needs.

Highly sensitized patients listed for heart after liver transplantation with or without domino.

For patients with end-stage heart disease and borderline hemodynamics, high human leukocyte antigen allosensitization presents a barrier to heart transplantation in a timely manner. Conventional desensitization protocols are inadequate in this context due to time constraints and for the most highly reactive immunologically. We previously reported performing heart after liver transplant with domino liver transplant on a single patient without liver disease.

When cardiomyopathy, cancer, and COVID-19 collide: A case report.

Malignancy has historically prohibited solid organ transplant; however, patients with effectively treated, favorable-risk cancers should not necessarily be eliminated as transplant candidates. These cases require careful review by a multidisciplinary team. Here, we report the case of a woman with end-stage heart failure undergoing heart transplant evaluation during the COVID pandemic who was found to have early-stage, hormone receptor-positive breast cancer.

Cardiac macrophages adopt profibrotic/M2 phenotype in infarcted hearts: Role of urokinase plasminogen activator.

Background: Macrophages (mac) that over-express urokinase plasminogen activator (uPA) adopt a profibrotic M2 phenotype in the heart in association with cardiac fibrosis. We tested the hypothesis that cardiac macs are M2 polarized in infarcted mouse and human hearts and that polarization is dependent on mac-derived uPA.

Methods: Studies were performed using uninjured (UI) or infarcted (MI) hearts of uPA overexpressing (SR-uPA), uPA null, or nontransgenic littermate (Ntg) mice.

Right ventricular sarcoidosis: is it time for updated diagnostic criteria?

A 55-year-old woman with a history of complete heart block, atrial flutter, and progressive right ventricular failure was referred to our tertiary care center to be evaluated for cardiac transplantation. The patient's clinical course included worsening right ventricular dysfunction for 3 years before the current evaluation. Our clinical findings raised concerns about arrhythmogenic right ventricular cardiomyopathy.

Human embryonic-stem-cell-derived cardiomyocytes regenerate non-human primate hearts.

Pluripotent stem cells provide a potential solution to current epidemic rates of heart failure by providing human cardiomyocytes to support heart regeneration. Studies of human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) in small-animal models have shown favourable effects of this treatment. However, it remains unknown whether clinical-scale hESC-CM transplantation is feasible, safe or can provide sufficient myocardial regeneration.

Electrical Integration of Human Embryonic Stem Cell-Derived Cardiomyocytes in a Guinea Pig Chronic Infarct Model.

Background: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) were recently shown to be capable of electromechanical integration following direct injection into intact or recently injured guinea pig hearts, and hESC-CM transplantation in recently injured hearts correlated with improvements in contractile function and a reduction in the incidence of arrhythmias. The present study was aimed at determining the ability of hESC-CMs to integrate and modulate electrical stability following transplantation in a chronic model of cardiac injury.

Methods And Results: At 28 days following cardiac cryoinjury, guinea pigs underwent intracardiac injection of hESC-CMs, noncardiac hESC derivatives (non-CMs), or vehicle.

Effects of cell grafting on coronary remodeling after myocardial infarction.

Background: With recent advances in therapeutic applications of stem cells, cell engraftment has become a promising therapy for replacing injured myocardium after infarction. The survival and function of injected cells, however, will depend on the efficient vascularization of the new tissue. Here we describe the arteriogenic remodeling of the coronary vessels that supports vascularization of engrafted tissue postmyocardial infarction (post-MI).

Delivery of basic fibroblast growth factor with a pH-responsive, injectable hydrogel to improve angiogenesis in infarcted myocardium.

A pH- and temperature-responsive, injectable hydrogel has been designed to take advantage of the acidic microenvironment of ischemic myocardium. This system can improve therapeutic angiogenesis methods by providing spatio-temporal control of angiogenic growth factor delivery. The pH- and temperature-responsive random copolymer, poly(N-isopropylacrylamide-co-propylacrylic acid-co-butyl acrylate) (p[NIPAAm-co-PAA-co-BA]), was synthesized by reversible addition fragmentation chain transfer polymerization.

Sildenafil reverses cardiac dysfunction in the mdx mouse model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a progressive and fatal genetic disorder of muscle degeneration. Patients with DMD lack expression of the protein dystrophin as a result of mutations in the X-linked dystrophin gene. The loss of dystrophin leads to severe skeletal muscle pathologies as well as cardiomyopathy, which manifests as congestive heart failure and arrhythmias.

The role of macrophage-derived urokinase plasminogen activator in myocardial infarct repair: urokinase attenuates ventricular remodeling.

Cardiac plasmin activity is increased following myocardial ischemia. To test the hypothesis that macrophage-derived uPA is a key mediator of repair following myocardial infarction, we performed myocardial infarction on mice with macrophage-specific over-expression of uPA (SR-uPA mice). SR-uPA(+/0) mice and wild-type littermates were sacrificed at 5 days or 4 weeks after infarction and cardiac content of macrophages, collagen, and myofibroblasts was quantified.

Cardiogenic differentiation and transdifferentiation of progenitor cells.

In recent years, cell transplantation has drawn tremendous interest as a novel approach to preserving or even restoring contractile function to infarcted hearts. A typical human infarct involves the loss of approximately 1 billion cardiomyocytes, and, therefore, many investigators have sought to identify endogenous or exogenous stem cells with the capacity to differentiate into committed cardiomyocytes and repopulate lost myocardium. As a result of these efforts, dozens of stem cell types have been reported to have cardiac potential.

Cardiomyocytes derived from human embryonic stem cells in pro-survival factors enhance function of infarcted rat hearts.

Cardiomyocytes derived from human embryonic stem (hES) cells potentially offer large numbers of cells to facilitate repair of the infarcted heart. However, this approach has been limited by inefficient differentiation of hES cells into cardiomyocytes, insufficient purity of cardiomyocyte preparations and poor survival of hES cell-derived myocytes after transplantation. Seeking to overcome these challenges, we generated highly purified human cardiomyocytes using a readily scalable system for directed differentiation that relies on activin A and BMP4.

Chemical dimerization of fibroblast growth factor receptor-1 induces myoblast proliferation, increases intracardiac graft size, and reduces ventricular dilation in infarcted hearts.

The ability to control proliferation of grafted cells in the heart and consequent graft size could dramatically improve the efficacy of cell therapies for cardiac repair. To achieve targeted graft cell proliferation, we created a chimeric receptor (F36Vfgfr-1) composed of a modified FK506-binding protein (F36V) fused with the cytoplasmic domain of the fibroblast growth factor receptor-1 (FGFR-1). We retrovirally transduced mouse C2C12 and MM14 skeletal myoblasts with this construct and treated them with AP20187, a dimeric F36V ligand ("dimerizer"), in vitro and in vivo to induce receptor dimerization.

Transplantation of undifferentiated murine embryonic stem cells in the heart: teratoma formation and immune response.

Embryonic stem (ES) cells are promising for cardiac repair, but directing their differentiation toward cardiomyocytes remains challenging. We investigated whether the heart guides ES cells toward cardiomyocytes in vivo and whether allogeneic ES cells were immunologically tolerated. Undifferentiated mouse ES cells consistently formed cardiac teratomas in nude or immunocompetent syngeneic mice.

rAAV6-microdystrophin preserves muscle function and extends lifespan in severely dystrophic mice.

Mice carrying mutations in both the dystrophin and utrophin genes die prematurely as a consequence of severe muscular dystrophy. Here, we show that intravascular administration of recombinant adeno-associated viral (rAAV) vectors carrying a microdystrophin gene restores expression of dystrophin in the respiratory, cardiac and limb musculature of these mice, considerably reducing skeletal muscle pathology and extending lifespan. These findings suggest rAAV vector-mediated systemic gene transfer may be useful for treatment of serious neuromuscular disorders such as Duchenne muscular dystrophy.

The effects of atorvastatin (10 mg) on systemic inflammation in heart failure.

In observational studies, statins are associated with lower mortality in patients with heart failure (HF), including those with nonischemic HF. Such benefits could be related to anti-inflammatory effects; however, the effects of statins on systemic inflammation in HF are not well-established. We conducted a 16-week, single-center, randomized, double-blind, placebo-controlled, crossover clinical trial of the effects of atorvastatin 10 mg/day on concentrations of systemic inflammatory markers in 22 patients with HF (including 20 with nonischemic HF) with New York Heart Association class II or III symptoms and left ventricular ejection fraction of <40%.

Extracardiac progenitor cells repopulate most major cell types in the transplanted human heart.

Background: Extracardiac progenitor cells are capable of repopulating cardiomyocytes at very low levels in the human heart after injury. Here, we explored the extent of endothelial, smooth muscle, and Schwann cell chimerism in patients with sex-mismatched (female-to-male) heart transplants.

Methods And Results: Autopsy specimens from 5 patients and endomyocardial biopsies from 7 patients were used for this study.

Gene transfer of connexin43 into skeletal muscle.

Cellular cardiomyoplasty using skeletal myoblasts may be beneficial for infarct repair. One drawback to skeletal muscle cells is their lack of gap junction expression after differentiation, thus preventing electrical coupling to host cardiomyocytes. We sought to overexpress the gap junction protein connexin43 (Cx43) in differentiated skeletal myotubes, using retroviral, adenoviral, and plasmid-mediated gene transfer.

NFATc3-induced reductions in voltage-gated K+ currents after myocardial infarction.

Reductions in voltage-activated K+ (Kv) currents may underlie arrhythmias after myocardial infarction (MI). We investigated the role of beta-adrenergic signaling and the calcineurin/NFAT pathway in mediating the reductions in Kv currents observed after MI in mouse ventricular myocytes. Kv currents were produced by the summation of 3 distinct currents: I(to), I(Kslow1), and I(Kslow2).

Evidence for fusion between cardiac and skeletal muscle cells.

Cardiomyoplasty with skeletal myoblasts may benefit cardiac function after infarction. Recent reports indicate that adult stem cells can fuse with other cell types. Because myoblasts are "fusigenic" cells by nature, we hypothesized they might be particularly likely to fuse with cardiomyocytes.