Human Heart Disease Research Articles

A Latent Cardiomyocyte Regeneration Potential in Human Heart Disease.

Cardiomyocytes in the adult human heart show a regenerative capacity, with an annual renewal rate of ≈0.5%. Whether this regenerative capacity of human cardiomyocytes is employed in heart failure has been controversial. We determined cardiomyocyte renewal in 52 patients with advanced heart failure, 28 of whom received left ventricular assist device support. We measured the concentration of nuclear bomb test-derived 14C in cardiomyocyte genomic DNA and performed mathematical modeling to establish cardiomyocyte renewal in heart failure with and without LVAD unloading. We show that cardiomyocyte generation is minimal in end-stage heart failure patients at rates 18 to 50× lower compared with the healthy heart. However, patients receiving left ventricle support device therapy, who showed significant functional and structural cardiac improvement, had a >6-fold increase in cardiomyocyte renewal relative to the healthy heart. Our findings reveal a substantial cardiomyocyte regeneration potential in human heart disease, which could be exploited therapeutically.

Abstract 4141486: Site-Specific Transcriptomic Patterns and Cell Types Associated with Hypertension

Introduction: The biology of early human hypertensive heart disease (HHD) is largely unexplored due to limited cardiac tissue access. Site-specific transcriptomics of human cardiac tissue before development of overt HHD offers a unique vantage to understand the biology of HHD in human cardiac tissue. Hypothesis: We hypothesize that transcriptomic signatures and cell subtype proportions differ in human heart tissue from HTN donors compared to normotensive (NTN) donors in a site-specific manner. Methods: We performed bulk RNA-seq on rRNA-depleted libraries from left (LV) and right (RV) mid-ventricular-wall tissue (average depth 114 million reads/sample) collected postmortem from HTN (n=3, 67% Black/Latinx) and NTN (n=2, 50% Black/Latinx) donors. We performed single-nucleus RNA-seq (snRNA-Seq) on cardiac tissue from the same donors (average of 4,062 LV nuclei). Differential gene expression, lineage identification, and Gene Set Enrichment Analysis (GSEA) were performed with publicly available software. Results: All donors were female with matched postmortem intervals (time from death to tissue preservation; HTN 19±9 hours, NTN 18±6 hours). HTN donors were older (65±7 years) than NTN donors (36±16 years). A total of 416 genes were associated with HTN (Wald test, FDR q <0.05) across both ventricles (correcting for site). When tested separately, 72 (LV) or 83 (RV) genes were associated with HTN (FDR q <0.05), with 13 common genes, indicating site-specific differences. GSEA of genes ranked by Wald statistic computed across both ventricles showed that transcripts involved in single-stranded DNA helicase activity, branched-chain amino acid catabolism, and NAD-dependent deacetylase activity were coordinately associated with HTN (FDR q <0.05). snRNA-seq revealed 9 cell types in these samples, including immune cells and chamber-specific cardiomyocytes (CMs) with higher proportions of LV CMs and lymphocytes associated with HTN compared to NTN. MYH6 and MYL7 expression was unchanged with respect to HTN by RNA-seq but lower in LV HTN CMs compared to NTN by snRNA-seq, suggesting dysregulation of contractile programming in HTN LV CMs. Conclusion: HTN is associated with altered cardiomyocyte/lymphocyte ratios, and site-specific differential expression of cardiac contractile elements. Further study is required to validate these findings with additional samples and elucidate mechanisms driving transcriptional program differences in the hypertensive human heart.

First trimester maternal infections and offspring congenital heart defects: a systematic review and meta-analysis

Abstract Background Maternal infections early in pregnancy have been proposed as playing a role in the development of congenital heart defects. We aimed to summarise contemporary evidence regarding the association between first-trimester maternal infection and risk of offspring congenital heart defects. Methods For this systematic review and meta-analysis, we searched Medline and Embase for studies reporting associations of at least one measure of maternal infection during pregnancy and offspring congenital heart disease in humans and published in English between January 1, 1990 and February 13, 2024. Studies were eligible for inclusion if they reported rates of offspring congenital heart defects among both infected and non-infected mothers, and included a minimum of 50 offspring with congenital heart defects. We stratified associations by type of infection and type of heart defect when data from at least two studies were available. We used inverse variance weighted random-effect meta-analyses to pool the estimates. In main analyses, we pooled crude estimates from studies reporting maternal infections during the first trimester of pregnancy. We performed sensitivity analyses to include studies that i) investigated infections later in pregnancy or at unspecified time-points, and ii) adjusted for potential confounders such as maternal age, socioeconomic status, or ethnicity. Findings: We identified 11 studies (7 case control studies, 4 cohort studies) with data from 1,805,115 pregnancies. Nine of these studies assessed maternal infectious status through self-reported questionnaires or medical records, two used laboratory antibody testing and three reported on specific infectious pathogens. Studies reported on various types of bacterial and viral infections, including influenza, urinary tract infections, cytomegalovirus, herpes simplex virus, or chlamydia, with varying effect sizes. Ten studies reported a positive association between maternal infection variables and offspring congenital heart defects, with a pooled odds ratio (OR) and 95% confidence interval of 1.56 (1.27, 1.91) across all types of infections. Associations differed by individual subtype of congenital heart defects, with ORs ranging from 1.28 (0.89, 1.85) for pulmonary atresia to 1.75 (1.23, 2.49) for ventricular septal defects. Sensitivity analyses that included infections measured later in pregnancy, or adjusted rates for potential confounders, showed broadly similar trends but attenuated effect sizes. Interpretation: First trimester maternal infections are associated with increased risk of congenital heart defects. Associations appear to vary by type of infection and type of congenital heart defect, and to extend beyond infections commonly tested for during routine pregnancy screening. Larger-scale studies are warranted to confirm these findings using laboratory antibody testing and investigating how these associations vary by specific pathogens and subtypes of congenital heart defects.

Molecular regulation of reversible cardiac remodeling: lessons from species with extreme physiological adaptations.

Some vertebrates evolved to have a remarkable capacity for anatomical and physiological plasticity in response to environmental challenges. One example of such plasticity can be found in the ambush-hunting snakes of the genus Python, which exhibit reversible cardiac growth with feeding. The predation strategy employed by pythons is associated with months-long fasts that are arrested by ingestion of large prey. Consequently, digestion compels a dramatic increase in metabolic rate and hypertrophy of multiple organs, including the heart. In this Review, we summarize the post-prandial cardiac adaptations in pythons at the whole-heart, cellular and molecular scales. We highlight circulating factors and cellular signaling pathways that are altered during digestion to affect cardiac form and function and propose possible mechanisms that may drive the post-digestion regression of cardiac mass. Adaptive physiological cardiac hypertrophy has also been observed in other vertebrates, including in fish acclimated to cold water, birds flying at high altitudes and exercising mammals. To reveal potential evolutionarily conserved features, we summarize the molecular signatures of reversible cardiac remodeling identified in these species and compare them with those of pythons. Finally, we offer a perspective on the potential of biomimetics targeting the natural biology of pythons as therapeutics for human heart disease.

KTz Neuron in Electromagnetic Radiation with a Novel Flux-Controlled Memristor

In this paper, a novel discrete flux-controlled generalized memristor is proposed to be used in Electromagnetic Radiation (EMR) KTz neuron. The introduction of flux-controlled memristor can simulate the behavior changes of the neuron under EMR. The stability of flux-controlled memristor EMR KTz Neuron (EKN) map is discussed, and the fixed point of the system is characterized. With the change of parameters, the complex and rich dynamical characteristics of the EKN map are demonstrated. The firing patterns under different initial values are also investigated, and discharge waveforms similar in general shape and structure to human heart and brain disease phenomena are analyzed. Finally, the hardware implementation is verified on the Digital Signal Processing (DSP) platform. The results show that these findings are of great value for the practical applications of neural networks, with a theoretical basis provided.

Abstract Mo123: Post-transcriptional Mechanisms of BAG3 Regulation in Ischemia-Reperfusion Injury

The co-chaperone BAG3 is critical for protein quality control at the cardiac sarcomere. BAG3 binds to Hsp70 and coordinates the assembly of the CASA (chaperone-assisted selective autophagy) complex, thus supporting protein homeostasis and cardiomyocyte contractility. Decreased BAG3 levels are associated with heart disease, whereas BAG3 overexpression rescues ventricular function in animal models of heart failure (HF). Despite BAG3’s potential as a therapeutic target, the mechanisms underlying BAG3 regulation are largely unresolved. Here, we investigate the mechanisms of BAG3 downregulation after stress. We found that BAG3 protein is reduced in human cardiomyopathies compared to non-failing hearts, yet there is an increase in bag3 mRNA transcript, suggesting BAG3’s downregulation in heart disease may be controlled post-transcriptionally. To identify these post-transcriptional pathways, we subjected neonatal rat ventricular myocytes (NRVMs) to prolonged hypoxia-reoxygenation (H/R) stress, which recapitulated the decrease in BAG3 levels observed in human heart disease. Notably, disrupting Hsp70 binding to BAG3 in NRVMs via the drug JG-98 decreased BAG3’s half-life by ~90%, suggesting that Hsp70 protects BAG3 from degradation. Loss of Hsp70-mediated protection could contribute to declining BAG3 levels, so we quantified Hsp70 abundance after H/R stress in NRVMs, finding no significant change. We also found that overexpressing inducible Hsp70 did not rescue BAG3 levels. This data suggests that BAG3 downregulation in H/R stress is not caused by loss of Hsp70 binding/protection. To examine BAG3 regulation in vivo, we subjected wildtype mice to ischemia-reperfusion injury. After 24 hours, we observed a decrease in BAG3 levels in the left ventricle and no significant change in Hsp70 abundance. Interestingly, the decline in full-length BAG3 (85 kDa) was accompanied by an increase in a BAG3 cleavage product at 74 kDa. We analyzed this product via mass spectrometry, discovering that it lacks a third of the WW domain, which is involved in autophagy. In future experiments, BAG3 cleavage will be explored as a potential mechanism of BAG3 loss. Such mechanisms will provide insight into how to maintain BAG3 levels, and thus cardiac function, during stress.

Evaluation of the Canonical Wnt Signaling Pathway in the Hearts of Hypertensive Rats of Various Etiologies.

Wnt/β-catenin signaling dysregulation is associated with the pathogenesis of many human diseases, including hypertension and heart disease. The aim of this study was to immunohistochemically evaluate and compare the expression of the Fzd8, WNT1, GSK-3β, and β-catenin genes in the hearts of rats with spontaneous hypertension (SHRs) and deoxycorticosterone acetate (DOCA)-salt-induced hypertension. The myocardial expression of Fzd8, WNT1, GSK-3β, and β-catenin was detected by immunohistochemistry, and the gene expression was assessed with a real-time PCR method. In SHRs, the immunoreactivity of Fzd8, WNT1, GSK-3β, and β-catenin was attenuated in comparison to that in normotensive animals. In DOCA-salt-induced hypertension, the immunoreactivity of Fzd8, WNT1, GSK-3β, and β-catenin was enhanced. In SHRs, decreases in the expression of the genes encoding Fzd8, WNT1, GSK-3β, and β-catenin were observed compared to the control group. Increased expression of the genes encoding Fzd8, WNT1, GSK-3β, and β-catenin was demonstrated in the hearts of rats with DOCA-salt-induced hypertension. Wnt signaling may play an essential role in the pathogenesis of arterial hypertension and the accompanying heart damage. The obtained results may constitute the basis for further research aimed at better understanding the role of the Wnt/β-catenin pathway in the functioning of the heart.

Association between plasma proteome and pulmonary heart disease: A two-stage Mendelian randomization analysis.

Pulmonary heart disease (PHD) involves altered structure and function of the right ventricle caused by an abnormal respiratory system that causes pulmonary hypertension. However, the association between changes in plasma proteomics and PHD remains unclear. Hence, we aimed to identify causal associations between genetically predicted plasma protein levels and PHD. Mendelian randomization was performed to test the target proteins associated with PHD. Summary statistics for the human plasma proteome and pulmonary heart disease were acquired from the UK Biobank (6038 cases and 426 977 controls) and the FinnGen study (6753 cases and 302 401 controls). Publicly available pQTLs datasets for human plasma proteins were obtained from a largescale genome-wide association study in the INTERVAL study. The results were validated using a case-control cohort. We first enrolled 3622 plasma proteins with conditionally independent genetic variants; three proteins (histo-blood group ABO system transferase, activating signal cointegration 1 complex subunit 1, and calcium/calmodulin-dependent protein kinase I [CAMK1]) were significantly associated with the risk of pulmonary heart disease in the UK Biobank cohort. Only CAMK1 was successfully replicated (odds ratio: 1.1056, 95% confidence interval: 1.019-1.095, p = 0.0029) in the FinnGen population. In addition, the level of CAMK1 in 40 patients with PHD was significantly higher (p = 0.023) than that in the control group. This work proposes that CAMK1 is associated with PHD, underscoring the importance of the calcium signaling pathway in the pathophysiology to improve therapies for PHD.

Experimental Animal Models in Heart Disease

Heart diseases constitute a significant global burden of mortality and morbidity. This encompassing word refers to a variety of illnesses, including coronary artery disease, heart failure, myocardial infarction, and valvular heart disease. Given the imperative need to comprehend and address these ailments, experimental studies are indispensable. Experimental animal models serve as indispensable tools in elucidating the mechanisms of heart disease. They are pivotal for developing novel treatments and assessing the efficacy of existing therapies. Among the commonly utilized animal models in heart disease research are mice, rats, rabbits, dogs, and pigs. Each model offers distinct advantages and limitations, allowing researchers to probe specific facets of cardiac pathology and unravel the intricate mechanisms involved in heart disease. In this comprehensive review, it was aimed to provide a succinct overview of the various animal models employed in heart disease research. The advantages and drawbacks of each model were delineated, the aspects of human heart disease they emulate were elucidated, and pivotal research findings facilitated by their utilization were highlighted. By synthesizing this information, it was the endeavor to provide researchers and clinicians with valuable insights into the diverse array of animal models available for investigating heart diseases, ultimately paving the way for enhanced understanding and treatment of these debilitating conditions.

Unveiling new horizons in heart research: the promise of multi-chamber cardiac organoids

Human cardiac and other organoids have recently emerged as a groundbreaking tool for advancing our understanding the developmental biology of human organs. A recent paper from Sasha Mendjan’s laboratory published in the journal Cell on December 7, 2023, reported the generation of multi-chamber cardioids from human pluripotent stem cells, a transformative technology in the field of cardiology. In this short highlight paper, we summarize their findings. Their cardioids remarkably recapitulate the complexity of the human embryonic heart, including tissue architecture, cellular diversity, and functionality providing an excellent in vitro model for investigation of human heart development, disease modeling, precision medicine, and regenerative medicine. Thus, generating cardioids is an important step forward for understanding human heart development and developing potential therapies for heart diseases.

Differentiation of Pluripotent Stem Cells for Disease Modeling: Learning from Heart Development.

Heart disease is a pressing public health problem and the leading cause of death worldwide. The heart is the first organ to gain function during embryogenesis in mammals. Heart development involves cell determination, expansion, migration, and crosstalk, which are orchestrated by numerous signaling pathways, such as the Wnt, TGF-β, IGF, and Retinoic acid signaling pathways. Human-induced pluripotent stem cell-based platforms are emerging as promising approaches for modeling heart disease in vitro. Understanding the signaling pathways that are essential for cardiac development has shed light on the molecular mechanisms of congenital heart defects and postnatal heart diseases, significantly advancing stem cell-based platforms to model heart diseases. This review summarizes signaling pathways that are crucial for heart development and discusses how these findings improve the strategies for modeling human heart disease in vitro.

The expanded spectrum of human disease associated with GREB1L likely includes complex congenital heart disease.

GREB1L has been linked prenatally to Potter's sequence, as well as less severe anomalies of the kidney, uterus, inner ear, and heart. The full phenotypic spectrum is unknown. The purpose of this study was to characterize known and novel pre- and postnatal phenotypes associated with GREB1L. We solicited cases from the Fetal Sequencing Consortium, screened a population-based genomic database, and conducted a comprehensive literature search to identify disease cases associated with GREB1L. We present a detailed phenotypic spectrum and molecular changes. One hundred twenty-seven individuals with 51 unique pathogenic or likely pathogenic GREB1L variants were identified. 24 (47%) variants were associated with isolated kidney anomalies, 19 (37%) with anomalies of multiple systems, including one case of hypoplastic left heart syndrome, five (10%) with isolated sensorineural hearing loss, two (4%) with isolated uterine agenesis; and one (2%) with isolated tetralogy of Fallot. GREB1L may cause complex congenital heart disease (CHD) in humans. Clinicians should consider GREB1L testing in the setting of CHD, and cardiac screening in the setting of GREB1L variants.

GCN5L1-mediated acetylation prevents Rictor degradation in cardiac cells after hypoxic stress

Cardiomyocyte apoptosis and cardiac fibrosis are the leading causes of mortality in patients with ischemic heart disease. As such, these processes represent potential therapeutic targets to treat heart failure resulting from ischemic insult. We previously demonstrated that the mitochondrial acetyltransferase protein GCN5L1 regulates cardiomyocyte cytoprotective signaling in ischemia-reperfusion injury in vivo and hypoxia-reoxygenation injury in vitro. The current study investigated the mechanism underlying GCN5L1-mediated regulation of the Akt/mTORC2 cardioprotective signaling pathway. Rictor protein levels in cardiac tissues from human ischemic heart disease patients were significantly decreased relative to non-ischemic controls. Rictor protein levels were similarly decreased in cardiac AC16 cells following hypoxic stress, while mRNA levels remained unchanged. The reduction in Rictor protein levels after hypoxia was enhanced by the knockdown of GCN5L1, and was blocked by GCN5L1 overexpression. These findings correlated with changes in Rictor lysine acetylation, which were mediated by GCN5L1 acetyltransferase activity. Rictor degradation was regulated by proteasomal activity, which was antagonized by increased Rictor acetylation. Finally, we found that GCN5L1 knockdown restricted cytoprotective Akt signaling, in conjunction with decreased mTOR abundance and activity. In summary, these studies suggest that GCN5L1 promotes cardioprotective Akt/mTORC2 signaling by maintaining Rictor protein levels through enhanced lysine acetylation.

Profibrotic VEGFR3-Dependent Lymphatic Vessel Growth in Autoimmune Valvular Carditis.

Rheumatic heart disease is the major cause of valvular heart disease in developing nations. Endothelial cells (ECs) are considered crucial contributors to rheumatic heart disease, but greater insight into their roles in disease progression is needed. We used a Cdh5-driven EC lineage-tracing approach to identify and track ECs in the K/B.g7 model of autoimmune valvular carditis. Single-cell RNA sequencing was used to characterize the EC populations in control and inflamed mitral valves. Immunostaining and conventional histology were used to evaluate lineage tracing and validate single-cell RNA-sequencing findings. The effects of VEGFR3 (vascular endothelial growth factor receptor 3) and VEGF-C (vascular endothelial growth factor C) inhibitors were tested in vivo. The functional impact of mitral valve disease in the K/B.g7 mouse was evaluated using echocardiography. Finally, to translate our findings, we analyzed valves from human patients with rheumatic heart disease undergoing mitral valve replacements. Lineage tracing in K/B.g7 mice revealed new capillary lymphatic vessels arising from valve surface ECs during the progression of disease in K/B.g7 mice. Unsupervised clustering of mitral valve single-cell RNA-sequencing data revealed novel lymphatic valve ECs that express a transcriptional profile distinct from other valve EC populations including the recently identified PROX1 (Prospero homeobox protein 1)+ lymphatic valve ECs. During disease progression, these newly identified lymphatic valve ECs expand and upregulate a profibrotic transcriptional profile. Inhibiting VEGFR3 through multiple approaches prevented expansion of this mitral valve lymphatic network. Echocardiography demonstrated that K/B.g7 mice have left ventricular dysfunction and mitral valve stenosis. Valve lymphatic density increased with age in K/B.g7 mice and correlated with worsened ventricular dysfunction. Importantly, human rheumatic valves contained similar lymphatics in greater numbers than nonrheumatic controls. These studies reveal a novel mode of inflammation-associated, VEGFR3-dependent postnatal lymphangiogenesis in murine autoimmune valvular carditis, with similarities to human rheumatic heart disease.

Epigenetic Regulation of Cardiomyocyte Maturation by Arginine Methyltransferase CARM1.

During the neonatal stage, the cardiomyocyte undergoes a constellation of molecular, cytoarchitectural, and functional changes known collectively as cardiomyocyte maturation to increase myocardial contractility and cardiac output. Despite the importance of cardiomyocyte maturation, the molecular mechanisms governing this critical process remain largely unexplored. We leveraged an in vivo mosaic knockout system to characterize the role of Carm1, the founding member of protein arginine methyltransferase, in cardiomyocyte maturation. Using a battery of assays, including immunohistochemistry, immuno-electron microscopy imaging, and action potential recording, we assessed the effect of loss of Carm1 function on cardiomyocyte cell growth, myofibril expansion, T-tubule formation, and electrophysiological maturation. Genome-wide transcriptome profiling, H3R17me2a chromatin immunoprecipitation followed by sequencing, and assay for transposase-accessible chromatin with high-throughput sequencing were used to investigate the mechanisms by which CARM1 (coactivator-associated arginine methyltransferase 1) regulates cardiomyocyte maturation. Finally, we interrogated the human syntenic region to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks for single-nucleotide polymorphisms associated with human heart diseases. We report that mosaic ablation of Carm1 disrupts multiple aspects of cardiomyocyte maturation cell autonomously, leading to reduced cardiomyocyte size and sarcomere thickness, severe loss and disorganization of T tubules, and compromised electrophysiological maturation. Genomics study demonstrates that CARM1 directly activates genes that underlie cardiomyocyte cytoarchitectural and electrophysiological maturation. Moreover, our study reveals significant enrichment of human heart disease-associated single-nucleotide polymorphisms in the human genomic region syntenic to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks. This study establishes a critical and multifaceted role for CARM1 in regulating cardiomyocyte maturation and demonstrates that deregulation of CARM1-dependent cardiomyocyte maturation gene expression may contribute to human heart diseases.

Hemodynamics During Development and Postnatal Life.

A well-developed heart is essential for embryonic survival. There are constant interactions between cardiac tissue motion and blood flow, which determine the heart shape itself. Hemodynamic forces are a powerful stimulus for cardiac growth and differentiation. Therefore, it is particularly interesting to investigate how the blood flows through the heart and how hemodynamics is linked to a particular species and its development, including human. The appropriate patterns and magnitude of hemodynamic stresses are necessary for the proper formation of cardiac structures, and hemodynamic perturbations have been found to cause malformations via identifiable mechanobiological molecular pathways. There are significant differences in cardiac hemodynamics among vertebrate species, which go hand in hand with the presence of specific anatomical structures. However, strong similarities during development suggest a common pattern for cardiac hemodynamics in human adults. In the human fetal heart, hemodynamic abnormalities during gestation are known to progress to congenital heart malformations by birth. In this chapter, we discuss the current state of the knowledge of the prenatal cardiac hemodynamics, as discovered through small and large animal models, as well as from clinical investigations, with parallels gathered from the poikilotherm vertebrates that emulate some hemodynamically significant human congenital heart diseases.

Discovery and functional investigation of BMP4 as a new causative gene for human congenital heart disease.

Aggregating evidence highlights the strong genetic basis underpinning congenital heart disease (CHD). Here BMP4 was chosen as a prime candidate gene causative of human CHD predominantly because BMP4 was amply expressed in the embryonic hearts and knockout of Bmp4 in mice led to embryonic demise mainly from multiple cardiovascular developmental malformations. The aim of this retrospective investigation was to discover a novel BMP4 mutation underlying human CHD and explore its functional impact. A sequencing examination of BMP4 was implemented in 212 index patients suffering from CHD and 236 unrelated non-CHD individuals as well as the family members available from the proband carrying a discovered BMP4 mutation. The impacts of the discovered CHD-causing mutation on the expression of NKX2-5 and TBX20 induced by BMP4 were measured by employing a dual-luciferase analysis system. A new heterozygous BMP4 mutation, NM_001202.6:c.318T>G;p.(Tyr106*), was found in a female proband affected with familial CHD. Genetic research of the mutation carrier's relatives unveiled that the truncating mutation was in co-segregation with CHD in the pedigree. The nonsense mutation was absent from 236 unrelated non-CHD control persons. Quantitative biologic measurement revealed that Tyr106*-mutant BMP4 failed to induce the expression of NKX2-5 and TBX20, two genes whose expression is lost in CHD. The current findings indicate BMP4 as a new gene predisposing to human CHD, allowing for improved prenatal genetic counseling along with personalized treatment of CHD patients.

The Genetics of Human Congenital Coronary Vascular Anomalies.

The genetics of human congenital coronary vascular anomalies (hCCVA) remains largely underresearched. This is surprising, because although coronary vascular defects represent a relatively small proportion of human congenital heart disease (CHD), hCCVAs are clinically significant conditions. Indeed, hCCVA frequently associate to other congenital cardiac structural defects and may even result in sudden cardiac death in the adult. In this brief chapter, we will attempt to summarize our current knowledge on the topic, also proposing a rationale for the development of novel approaches to the genetics of hCCVA.

Rat Model of Isoproterenol-Induced Myocardial Injury.

Isoproterenol (ISO) administration produces significant biochemical and histological changes including oxidative stress, reactive oxygen species (ROS) overproduction, and inflammation that leads to aggravation of myocardial injury. Subcutaneous or intraperitoneal ISO injection into rats can replicate several features of human heart disease, making it a useful tool for comprehending the underlying mechanisms and evaluating potential therapeutic strategies. In the present chapter, we elaborate on how depending on the precise experimental goals and the intended level of severity, different dosages and regimens are employed to induce myocardial injury.

A Novel Circular RNA circITGa9 Predominantly Generated in Human Heart Disease Induces Cardiac Remodeling and Fibrosis.

Recent studies have highlighted the pivotal roles of circular RNAs (circRNAs) in cardiovascular diseases. Through high-throughput circRNA sequencing of both normal myocardial tissues and hypertrophic patients, we unveiled 32,034 previously undiscovered circRNAs with distinct cardiac expression patterns. Notably, circITGa9, a circRNA derived from integrin-α9, exhibited substantial up-regulation in cardiac hypertrophy patients. This elevation was validated across extensive sample pools from cardiac patients and donors. Invivo experiments revealed heightened cardiac fibrosis in mice subjected to transverse aortic constriction (TAC) after circITGa9 injection. We identified circITGa9 binding proteins through circRNA precipitation followed by liquid chromatography tandem-mass spectrometry. Furthermore, circRNA pull-down/precipitation assays demonstrated that increased circITGa9 expression facilitated binding with tropomyosin 3 (TPM3). Specific binding sites between circITGa9 and TPM3 were identified through computational algorithms and further validated by site-directed mutagenesis. We further showed that circITGa9 induced actin polymerization, characteristic of tissue fibrosis. Finally, we developed approaches that improved cardiac function and decreased fibrosis by delivering small interfering RNA targeting circITGa9 or blocking oligo inhibiting the interaction of circITGa9 and TPM3 into TAC mice, which is amenable for further preclinical and translational development. We conclude that elevated circITGa9 levels drive cardiac remodeling and fibrosis. By pinpointing circITGa9 as a therapeutic target, we open doors to innovative interventions for mitigating cardiac remodeling and fibrosis.