bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcriptomic insights into cardiac healing - unveiling promising targets for effective gene therapies in diseased hearts
Authors: Caliandro R , Hanemaaijer J , Van Den Berg S , Gunst Q , Oostra R J , Van Den Hoff M , Gladka M M 
Published: May 2024

Abstract
Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation
Identifying therapeutical target genes is the first step towards developing new gene therapies to promote cardiac repair after injury. In the last decades, despite the many steps forward, not a single therapy has shown to be effective and suitable for human treatment of the injured heart. Considering that cardiac diseases represent one of the most prevalent causes of morbidity, disability, and mortality in the world, it is, therefore, essential to develop new and improved therapies to induce cardiac regeneration.
In this study, we aimed to identify novel therapeutical targets that could be used for future purposes of cardiac gene therapy. Unlike previous studies that investigated fetal hearts that are physiologically and functionally different from mature hearts, we focused on investigating adult human hearts that we collected from human donors with post-mortem time below 5 hours. Samples of left ventricles were molecularly and morphologically characterized for the presence of stress, cardiac damage, and cardiac fibrosis. Results of the molecular analyses were cross-referenced with the donors' medical history to classify each specimen as "control" or "diseased." Next, we performed single nuclei RNA sequencing of samples of the left ventricle from 2 "control" and 3 "diseased" hearts. Due to the adult tissue's complexity and the specimen's high-fiber content, we optimized the nuclei isolation protocol. Eventually, we successfully sequenced an average of 8.000 nuclei per sample with a gene coverage of approximately 800 genes per nucleus, identifying, via unsupervised cluster analysis, 17 different cell populations.
In cardiomyocytes, we identified over 500 genes differentially expressed in diseased hearts when compared to healthy controls. Among these genes, we discovered several novel target genes whose expression is increased only in diseased cardiomyocytes. Gene ontology analysis of the known interactors of the newly identified target genes shows enrichment in terms such as sarcomere organization, muscle contraction, mitochondrial energetics, calcium handling, and fatty acid metabolism.
Currently, we are investigating the molecular effects of the gain and loss of function of these genes in healthy iPS-derived cardiomyocytes and human-derived myocardial tissue slices to better understand their role in the pathophysiology of the adult human heart. From a therapeutic perspective, our ongoing research holds promises for developing new and improved intervention therapies to promote cardiac regeneration.
HCN2-based biological pacing in a modified rat AV-block model
Authors: Jonker T , Park K , Schroedel S , Neef K , Klerk M , Kirzner O F , Tan H L , Christoffels V M , Boink G J J 
Published: May 2024

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Eurostars - Heartpace 114245

Background
Electronic pacemakers have several important shortcomings which are difficult to overcome due to their hardware-based design. Gene therapy-based biological pacemakers may provide a different platform which can overcome these limitations. Such biological pacemaker strategies center around overexpression of the pacemaker ion channel HCN2, either alone or with other transgenes to potentiate pacemaker performance, such as the skeletal muscle sodium channel SkM1. In order to develop clinically applicable pacemaker gene therapies further engineering is needed, which would benefit from a reliable small animal model. At present it is unknown if the rat AV block model can be used to evaluate ion channel-based biological pacing.

Aim
In the present study, we aim to validate a modified rat AV-block model for the evaluation of HCN2 and SKM1-based biological pacing.

Methods
AV-block was generated in female rats by epicardially applied needle ablation of the AV-nodal region, as previously described (N.K. ). Complete AV-block was confirmed 7 days post-ablation by loss of P-wave and QRS-complex association on the body surface ECG. Seven days post-ablation, 3 groups of animals were injected into the left ventricular apex with Ad5-TNNT2-HCN2, Ad5-TNNT2-SkM1 or saline (control). 14 days post-ablation, ECG analysis was performed during anesthesia under baseline and after i.v. administration of isoprenaline. Upon completion of functional testing, tissue samples were harvested followed by gene expression analysis using qPCR.

Results
Injection of Ad5-TNNT2-HCN2, Ad5-TNNT2-SkM1 or saline did not result in ectopic activation patterns in baseline conditions 7 days after injection. Administration of isoprenaline results in reversal of the QRS complexes 90% of total measurement time in Ad5-TNNT2-HCN2 injected animals. Saline and Ad5-TNNT2-SkM1 showed no change in activation pattern upon isoprenaline administration. Gene expression analysis revealed expression of HCN2 in the injection site following Ad5-TNNT2-HCN2 injection, with minimal spread to non-target regions. However, this analysis also showed Ad5-TNNT2-SkM1 did not express well in this context.

Conclusion
Our modified rat AV-block model, when administered with isoprenaline, recapitulated expected biological pacemaker activity of HCN2 gene delivery. However, lack of effective expression of SkM1 renders direct comparison of these relevant transgenes difficult. Nevertheless, we expect this rat AV-block model can provide a valuable tool for the evaluation of novel ion channel-based biological pacemaker strategies.
Early biomarkers of disease in hypertrophic cardiomyopathy: does telomere length matter?
Authors: Judez Serrano A , Louchachha Medhi S , Munteanu S E M , Nicolas Rocamora M E , Sabater Molina M , Gimeno Blanes J R 
Published: May 2024

Abstract

Funding Acknowledgements
Type of funding sources: Public Institution(s). Main funding source(s): Biomedical Research Institute of Murcia (IMIB-Arrixaca)

Introduction
Hypertrophic cardiomyopathy (HCM) is the leading cause of sudden death in people under 35 years of age. (1) The variability of the phenotype together with its incomplete penetrance has been an obstacle to a complete understanding of the clinical spectrum and consequences of the disease. In recent years, there has been increasing interest in telomeric shortening and several authors have linked it to age-related diseases and HCM. (2, 3) Our aim was to study whether telomere length could affect the age at presentation and the severity of the HCM phenotype in genetic carriers.

Methods
Measurement of telomere length in circulating leukocytes (LTLc) was performed in 96 patients carrying a mutation in MYBPC3 causing HCM [58 affected (24 severely affected), 38 unaffected]. The variants included were c.2308+1G&gt;A, p.Pro108Alafs*9, p.Arg891Alafs*160 and p.Glu258Lys, all considered founder mutations in our region.
Peripheral venous blood samples were obtained from patients at the Inherited Heart Diseases Unit and stored at -80 ºC after informed consent had been signed by all participants.
For telomere length analysis, a telomeric restriction fragment (TRF) assay was performed using the TeloTAGGGTelomereLenghtAssay kit (Roche, 12209136001) according to the manufacturer's protocol with slight modifications.

Results
Our results show a lower LTLc in those affected patients with a more severe HCM phenotype compared to the affected and unaffected group (p=0.023) independently of age and sex, which are two variables that affect LTLc. Similarly, a shorter telomere length was associated with greater severity of the phenotype, with patients presenting a larger left atrial size (p=0.032), septal size (p=0.023) and greater obstruction (p=0.044). The presence of atrial fibrillation (p=0.039) and sudden death (p=0.024) was also higher in patients with shorter telomeres.

Conclusions
Telomere length is a variable that influences the expression of the phenotype in HCM patients carrying a MYBPC3 variant. This is an observation that supports the thesis of numerous publications linking HCM and other age-related diseases, sometimes called telomeropathies,(2) to telomere shortening. It has also been linked to non-hereditary conditions(3).
This fact sheds some light on the complex phenotypic variability present in HCM, raising LTL as a promising prognostic biomarker of the disease, as has already been suggested by other authors.(4, 5, 6).Workflow in the telomere legth analysisClinical associations of LTLc
Swimming training induced sex-specific differences in cardiac hypertrophy and blood levels of the renin-angiotensin system
Authors: Otmani Idrissi M O I , Frobert F A , De Chambrier A C , Stumpe M S , Fluck M F , Nikodemski M N , Giraud M N G 
Published: May 2024

Abstract

Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): FNS

Background
Exercise promotes physiological cardiac hypertrophy that is adaptive and reversible and influenced by age, genetics, sex, exercise intensity and type. The renin-angiotensin system (RAS) plays a crucial role in cardiovascular remodelling at both systemic and tissue levels. However, a significant gap exists in our understanding of sex differences in response to physical activity. Our objective is to characterise swimming-induced cardiac remodelling in female and male rats and RAS at both the cardiac tissue and systemic levels.

Methods
Male and female Lewis rats swam in a container filled with tap water at 32° C for 1 hour per day for 4 weeks or up to 8 weeks, respectively. Sedentary animals served as control. Echocardiography and immunostaining of RAS components, including angiotensin-converting enzyme 2 (ACE2) on cardiac sections' staining were performed. Cardiomyocyte (CM) size was measured. Cardiac RAS receptors were quantified with RT-PCR. Blood levels of Angiotensinogen, Angiotensins (Ang) were measured with Mass Spectrometry. Renin activity was calculated by the ratio Ang1/Angiotensinogen.

Results
After 4 weeks, an increase in ventricle diameter was shown in exercised male rats compared to the control. The cardiac hypertrophy was confirmed by increased heart/body weight (H/BW= 3x10-3±1.3x10-4vs2.5x10-3±3.10-5mg/g p&lt;0.0001) and CM size (288±23 vs 198±1μm2 p=0.0028) associated with increased intra-CM immunostained ACE2 (AC2 area fraction: 38.5%±2.8%vs20%±5 p=0.0001). In females, ventricle diameter was unchanged, but wall thickness increased. Exercise was pursued for up to 8 weeks. At 6 and 8 weeks, echocardiography measurements remained similar as at 4 weeks. Hypertrophy was then confirmed by increased H/BW (3.2x10-3±1.7x10-4vs control:2.7x103 ±1.8x104mg/g p&lt;0.0001) and CM size (335±47vs233±25μm2 p= 0.0019). An increased intra-CM-ACE2 was characterised by immunostaining (55.8%±6vs32.5%±6.6% p&lt;0.0001) and confirmed by the increased ACE2 gene expression in cardiac tissue.
At 4 weeks, the blood levels of RAS components were similar in trained and control males as well as renin activity. On contrary, exercised female rats showed increased blood levels of Angiotensinogen (4.2x10-4±7x10-5 vs 3x10-4±7x10-5au p=0.0288), Ang1 (2±1.9vs0.0±0.9au p=0.0151), Ang2 (1.2±1.5vs0.0±0.9au p=0.0204), and Ang1-7 (3.4±2.9vs 0.0±0.9au p=0.0058). The blood levels of these RAS compounds returned to the control levels after 6 and 8 weeks.
In addition, a sex-distinct blood proteome was identified.

Conclusion
Our results showed a sex-distinct RAS regulation post-exercise and suggested a sex difference in the timing of adaptive responses at the system and cardiac tissue levels.
Soluble guanylate cyclase stimulator as an emerging therapeutic option in the management of arrhythmias in heart failure rat model
Authors: Szeiffova Bacova B , Martiskova A , Sykora M , Gawrys O , Tribulova N , Cervenka L 
Published: May 2024

Abstract
Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): This research was supported by VEGA grant no. 2/0002/20 and 2/0006/23, the Slovak Research and Development Agency under contract no. 21-0410, European Regional Development Fund: ITMS2014+: 313011AVG3. This research was also partially supported by the Ministry of Health of the Czech Republic within the project for the development of the research organization [grant number 00023001 (IKEM)—institutional support] and also supported by the project National Institute for Research of Metabolic and Cardiovascular Diseases (Program EXCELES, Project No. LX22NPO5104)—Funded by the European Union—Next Generation EU
Heart failure (HF) is a complex clinical syndrome characterized by a decrease in the efficiency of the heart pump, leading to a decline in hemodynamic status and cardiac remodelling, that can contribute to the formation of a substrate for arrhythmias. Antiarrhythmic drug therapy is still suboptimal and current therapies are not efficacious enough. The purpose of the current study was therefore to examine the efficiency of nitric oxide (NO)/soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP) stimulator.
We used as an experimental model male hypertensive Ren-2 transgenic rats (TGR, n = 16), normotensive Hannover Sprague–Dawley rats (HSD, n = 17), and a rat model of HF surgically induced by aortocaval fistula (ACF) in rats of both strains (n = 27). After ACF induction were rats treated by sGC stimulator BAY41-8543 (3 mg/kg/day for 30 weeks) alone or combined with angiotensin-converting enzyme inhibitor (ACEi) Trandolapril (0.25 mg/kg/day for 30 weeks). Age of the animals at the end of the experiment was 40 weeks. Left ventricle tissue and plasma samples were used for further analyses.
Treatment by sGC stimulator significantly decreased rats' mortality, and systolic blood pressure, and significantly increased levels of antioxidant enzyme superoxide dismutase 1, matrix metalloproteinase 2, total and phosphorylated connexin 43 as well as protein kinase C epsilon, implicated in remodelling of extracellular matrix and intercellular communication, in the left ventricle of TGR rats. Application of sGC stimulator slightly normalized elevated collagen deposition and hydroxyproline content in the left ventricular tissue of TGR rats. Unfortunately, we did not observe any effect of the sGC stimulator in the TGR ACF group.
These results support the hypothesis that sGC stimulators might represent a class of drugs suitable for combating heart failure with partially anti-arrhythmic potential, but further studies are needed.
Transcriptional regulation of macrophage inflammation in the heart failure with preserved ejection fraction
Authors: Gorica E , Mohammed S A , Mengozzi A , Mongelli A , Telesca M , Wenzl F A , Ruschitzka F , Hamdani N , Costantino S , Paneni F 
Published: May 2024

Abstract

Funding Acknowledgements
None.

Introduction
Heart failure with preserved ejection fraction (HFpEF) is a global public health problem with no effective treatment available. Pro-inflammatory cardiac macrophages are emerging as key determinants of adverse left ventricular remodeling; however, their role in HFpEF remains poorly understood. Mechanistically, the recruitment and activation of macrophages represent a key event in maladaptive myocardial remodeling in HFpEF patients. Evidence suggests that remodeling processes in HFpEF hearts are orchestrated and amplified by cardiac macrophages which regulate cardiomyocyte function, endothelial cell activation and fibroblast differentiation. Here we sought to determine the role of macrophage inflammation in experimental and human HFpEF.

Methods
Experiments were performed in rat cardiomyocytes (H9c2), human endothelial cells (HAECS), transgenic mice, and left ventricular (LV) myocardial samples from patients with HFpEF. H9c2 and HAECS treated with pro-inflammatory macrophage-like cells (RAW 264.7) conditional media in the presence or knockdown of a top-ranking activator of M1 type macrophages such as nuclear receptor corepressor 1 (NCOR1), were used to elucidate better the involvement of this gene in transcriptional regulation in vitro. The cardiac function of myeloid cell-specific NCOR1 knockout HFpEF mice undergoing a high-fat diet and L-NAME was investigated. LV myocardial samples were used to evaluate the pro-inflammatory activity of macrophages in human HFpEF tissues.

Results
Human and murine LV specimens showed upregulation of vascular adhesion molecules (ICAM1, ICAM2, E-selectin), recruitment of M1 macrophages to the myocardium, and decreased M2 macrophages. Notably, NCOR1 deletion in macrophages protected against diastolic dysfunction, exercise intolerance, and myocardial inflammation (TNF-a, IL6, IL-1b). Mechanistically, induction of metabolic stress by palmitic acid induced macrophage polarization, upregulation of NCOR1 and inflammatory genes in RAW cells. By contrast, Finally, NCOR1 depletion prevented pro-inflammatory transcriptional programs and secretion of TNF-a, IL6 and IL-1b in the macrophage secretome.

Conclusion
Targeting macrophage NCOR1 could represent a promising approach to blunt myocardial inflammation in HFpEF.
Study of the cardiac sodium channel in a mouse model of Scn5a haploinsufficiency towards a novel approach of therapy
Authors: Ferrand M , Mougenot N , Laporte P L , Leclerc A , Algalarrondo V , Extramiana F , Charpentier F , Neyroud N 
Published: May 2024

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Sorbonne Université doctoral scolarship
INSERM

Introduction
Brugada syndrome (BrS) is an inherited cardiac arrhythmia that greatly increases the risk of sudden death as a result of ventricular fibrillation. Approximately 20% of BrS cases can be attributed to a mutation in SCN5A, the gene encoding the alpha-subunit Nav1.5 of the cardiac sodium-channel, which carries the sodium current INa. These mutations typically lead to loss-of-function of Nav1.5, resulting in a decrease in INa and most of them (»70 %) are responsible for haploinsufficiency. In the Scn5a+/- mouse model, a sodium-channel dysfunction phenotype is observed, characterized by conduction abnormalities (PR and QRS interval prolongation), a 50% reduction in INa, and an increased susceptibility to arrhythmias.

Aim
The aim of this study was to assess the impact of the overexpression of a Nav1.5-peptide, which has been found to enhance INa, in Scn5a+/- mice, as a novel approach of therapy.

Methods
We used AAV9-systemic injection to overexpress the Nav1.5-peptide into the heart of Scn5a+/- mice to gauge their susceptibility to arrhythmias induced by intracardiac pacing. We also examined the Nav1.5-peptide effects on endogenous Nav1.5 expression through molecular biology and biochemistry analyses.

Results
The duration of PR and QRS intervals in the hearts of Scn5a+/- mice was restored to normal by overexpression of the Nav1.5-peptide (PR interval = 46.3 ± 0.9 ms, n=22 in Scn5a+/- mice vs 40.4 ± 0.8 ms, n= 23 in WT mice, P&lt;0.0001 and 42.6 ± 0.9 ms, n=11 in Scn5a+/- +Nav1.5-peptide, P&lt;0.05; QRS interval = 15.2 ± 0.4, n=22 ms in Scn5a+/- mice vs 13.2 ± 0.4 ms, n=23 in WT mice, P&lt;0.01 and 13.6 ± 0.4 ms, n=14 in Scn5a+/- +Nav1.5-peptide, P&lt;0.05). Additionally, overexpression of the Nav1.5-peptide seemed to protect Scn5a+/- mice from induced arrhythmic events caused by programmed-ventricular stimulation (total premature beats = 1.3 ± 0.4 in Scn5a+/- mice, n = 13 vs 0.2 ± 0.2, n = 6 in injected Scn5a+/- mice, NS and 0.2 ± 0.2, n = 12 in WT mice, P&lt; 0.05). There were no significant differences in total Nav1.5 expression between injected and non-injected mice as shown by RT-qPCR and Western-blots, but the expression of Nav1.5 at the plasma membrane appeared to be restored by overexpression of the Nav1.5-peptide (Nav1.5/N-cadherin ratio = 0.50 ± 0.08, n = 11 in Scn5a+/- mice vs 1 ± 0.15, n= 11 in WT mice, P&lt; 0.05 and 0.94 ± 0.13, n = 11 in injected Scn5a+/- mice, P&lt; 0.05).

Conclusion
Gene therapy with Nav1.5-peptide can attenuate both conduction defects and increased arrhythmia inducibility observed in Scn5a+/- mice. Although additional studies will be needed to confirm and explore further our results, this could be promising to treat patients with « sodium-channel dysfunction » such as BrS.
In vivo calcium and voltage mapping of the zebrafish heart
Authors: Schepers D , Sieliwonczyck E , Vandendriessche B , Claes C , Bastianen J , Pintelon I , De Vos W , Snyders D , Alaerts M , Huisken J , Loeys B 
Published: May 2024

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Research Foundation Flanders (FWO)

Purpose
Inherited cardiac arrhythmias are characterized by a disturbance in the normal electrical functioning of the heart due to a dysfunction of cardiac ion channels, accessory proteins and/or structural components. This complex process is difficult to model in vitro, while in vivo mouse models differ substantially from humans with regards to cardiac electrophysiology. Thus, there is a need for alternative disease models in cardiac arrhythmia research. The zebrafish heart shows remarkable similarity to humans in its electrocardiogram and action potential (AP) morphology. Due to the optical translucency of zebrafish larvae, it is possible visualize the cardiac calcium and voltage dynamics across their entire hearts in vivo by use of genetically encoded calcium and voltage indicators (GECI and GEVI). We combined the fast kinetics of a next generation voltage reporter (Ace2N-mNeon) with a spectrally compatible calcium sensor (R-GECO) to create a sensitive high throughput method for in vivo characterization of the cardiac AP.

Methods
Ace2N-mNeon and R-GECO were expressed under control of a myocardial specific promoter via the Tol2kit system. The effect of sensor expression on normal physiology was assessed by patch clamp experiments. Fluorescence recordings were obtained with a Leica SP8 DLS microscope and a custom-built light sheet microscope. Our zebrafish sensor line was validated by experiments with quinidine drug exposure, as well as a novel model for long QT syndrome (LQTS) with a knock-in (KI) mutation in the cacna1c gene.

Results
Sensor expression did not significantly alter cardiac electrophysiology. The tg(myl7:Ace2N-mNeon/R-GECO) line demonstrated alterations in the heart rate, depolarization and repolarization induced by quinidine exposure. We observed a significantly prolonged ventricular repolarization in the LQTS KI line. Three-dimensional optical maps of AP characteristics across the entire zebrafish heart exhibited the physiological characteristics of the zebrafish cardiac electrophysiology, with activation initiated at the atrial venous pole and propagated towards the ventricular outflow tract, prolonged repolarization in the ventricles compared to the atria and slowed depolarization in the atrio-ventricular canal.

Conclusion
By expressing Ace2N-mNeon and R-GECO in the zebrafish heart, we were able to accurately detect drug- and mutation induced alterations in the cardiac AP, as well as AP characteristics across the entire heart, without compromising normal cardiac electrophysiology. Our transgenic line will provide a promising assay for future studies of cardiac arrhythmia.