Abstract P499: Histone H4K20 Trimethylation Is Differentially Regulated In Heart Disease

It has been well established that many cardiac pathologies result from dynamic changes in gene expression and conversely that modulating key epigenetic factors in murine models is capable of preventing or abrogating ischemic injury and pathological remodeling. One epigenetic mechanism is the post-translational modification of histones, which are reversibly methylated on lysine (K) residues and can accept up to three methyl groups (Me1, Me2 and Me3). In the heart, significant changes in global levels of histone H3K4Me3 and H3K9Me3 have been previously reported to be upregulated and downregulated, respectively, during hypertrophy and failure in mice. However, the majority of post-translational modifications on histones have never been examined to quantify global abundance in the heart during disease. In particular, histone H4K20Me3 is important in heterochromatin formation and gene repression in non-cardiac cells but has never been evaluated in the heart. Therefore, we utilized cardiac tissue from three animal models of cardiac stress and employed western blotting and mass spectrometry to quantify the global abundance of total histone H4 and H4K20 methylation. We specifically evaluated tissue from mice subjected to LAD ligation, transverse aortic banding and isoproterenol infusion (via mini-osmotic pump). In addition, we also utilized primary neonatal cardiomyocytes treated with the hypertrophic agonist phenylephrine to quantify H4K20 methylation. Our data show that global levels of histone H4K20Me3 are differentially regulated in some models of cardiac dysfunction, but not all (i.e. isoproterenol infusion). In addition, we measured the abundance of histone methyltransferases and demethylases (via western blotting and qPCR) which are responsible for adding or removing this methyl mark in mouse cardiac tissue, and compared this to published data from human heart failure patients. These analyses allowed us to identify two enzymes, the methyltransferase Smyd5 and demethylase KDM7B, which are also differentially expressed in cardiac tissue during disease. Together these results are the first analysis of histone H4K20 methylation in the heart and suggest a novel role for this methylation site in the pathophysiology of cardiovascular disease.

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Confocal imaging of calcium in intact ventricular muscle provides a new view of excitation-contraction coupling

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166154 ◽

1996 ◽

Vol 54 ◽

pp. 738-739

Author(s):

W.G. Wier

Keyword(s):

Local Control ◽

Cardiac Tissue ◽

Cell Function ◽

Isolated Heart ◽

Cardiac Cells ◽

Confocal Imaging ◽

Ion Concentration ◽

Heart Cell ◽

Free Calcium ◽

Heart Cells

A fundamentally new understanding of cardiac excitation-contraction (E-C) coupling is being developed from recent experimental work using confocal microscopy of single isolated heart cells. In particular, the transient change in intracellular free calcium ion concentration ([Ca2+]i transient) that activates muscle contraction is now viewed as resulting from the spatial and temporal summation of small (∼ 8 μm3), subcellular, stereotyped ‘local [Ca2+]i-transients' or, as they have been called, ‘calcium sparks'. This new understanding may be called ‘local control of E-C coupling'. The relevance to normal heart cell function of ‘local control, theory and the recent confocal data on spontaneous Ca2+ ‘sparks', and on electrically evoked local [Ca2+]i-transients has been unknown however, because the previous studies were all conducted on slack, internally perfused, single, enzymatically dissociated cardiac cells, at room temperature, usually with Cs+ replacing K+, and often in the presence of Ca2-channel blockers. The present work was undertaken to establish whether or not the concepts derived from these studies are in fact relevant to normal cardiac tissue under physiological conditions, by attempting to record local [Ca2+]i-transients, sparks (and Ca2+ waves) in intact, multi-cellular cardiac tissue.

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Cardiac Organoids to Model and Heal Heart Failure and Cardiomyopathies

Biomedicines ◽

10.3390/biomedicines9050563 ◽

2021 ◽

Vol 9 (5) ◽

pp. 563

Author(s):

Magali Seguret ◽

Eva Vermersch ◽

Charlène Jouve ◽

Jean-Sébastien Hulot

Keyword(s):

Tissue Engineering ◽

Drug Testing ◽

Cardiac Tissue ◽

Cardiac Tissue Engineering ◽

Cardiac Cells ◽

Cardiac Functions ◽

Different Types ◽

Recent Developments ◽

Human Cardiac Tissue ◽

Key Aspects

Cardiac tissue engineering aims at creating contractile structures that can optimally reproduce the features of human cardiac tissue. These constructs are becoming valuable tools to model some of the cardiac functions, to set preclinical platforms for drug testing, or to alternatively be used as therapies for cardiac repair approaches. Most of the recent developments in cardiac tissue engineering have been made possible by important advances regarding the efficient generation of cardiac cells from pluripotent stem cells and the use of novel biomaterials and microfabrication methods. Different combinations of cells, biomaterials, scaffolds, and geometries are however possible, which results in different types of structures with gradual complexities and abilities to mimic the native cardiac tissue. Here, we intend to cover key aspects of tissue engineering applied to cardiology and the consequent development of cardiac organoids. This review presents various facets of the construction of human cardiac 3D constructs, from the choice of the components to their patterning, the final geometry of generated tissues, and the subsequent readouts and applications to model and treat cardiac diseases.

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Recapitulating Cardiac Structure and Function In Vitro from Simple to Complex Engineering

Micromachines ◽

10.3390/mi12040386 ◽

2021 ◽

Vol 12 (4) ◽

pp. 386

Author(s):

Ana Santos ◽

Yongjun Jang ◽

Inwoo Son ◽

Jongseong Kim ◽

Yongdoo Park

Keyword(s):

Tissue Engineering ◽

Extracellular Matrix ◽

Computational Modeling ◽

Cardiac Tissue ◽

Cardiac Development ◽

Heart Tissue ◽

Cardiac Tissue Engineering ◽

Cardiac Cells

Cardiac tissue engineering aims to generate in vivo-like functional tissue for the study of cardiac development, homeostasis, and regeneration. Since the heart is composed of various types of cells and extracellular matrix with a specific microenvironment, the fabrication of cardiac tissue in vitro requires integrating technologies of cardiac cells, biomaterials, fabrication, and computational modeling to model the complexity of heart tissue. Here, we review the recent progress of engineering techniques from simple to complex for fabricating matured cardiac tissue in vitro. Advancements in cardiomyocytes, extracellular matrix, geometry, and computational modeling will be discussed based on a technology perspective and their use for preparation of functional cardiac tissue. Since the heart is a very complex system at multiscale levels, an understanding of each technique and their interactions would be highly beneficial to the development of a fully functional heart in cardiac tissue engineering.

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Bioengineered Cardiac Grafts

Circulation ◽

10.1161/circ.102.suppl_3.iii-56 ◽

2000 ◽

Vol 102 (suppl_3) ◽

Author(s):

Jonathan Leor ◽

Sharon Aboulafia-Etzion ◽

Ayelet Dar ◽

Lilia Shapiro ◽

Israel M. Barbash ◽

...

Keyword(s):

Cardiac Tissue ◽

Left Ventricular ◽

Cardiac Cells ◽

Sham Operation ◽

Complete Disappearance ◽

3 Dimensional ◽

Infarcted Myocardium ◽

Lv Remodeling ◽

And Function ◽

Conducive Environment

Background —The myocardium is unable to regenerate because cardiomyocytes cannot replicate after injury. The heart is therefore an attractive target for tissue engineering to replace infarcted myocardium and enhance cardiac function. We tested the feasibility of bioengineering cardiac tissue within novel 3-dimensional (3D) scaffolds. Methods and Results —We isolated and grew fetal cardiac cells within 3D porous alginate scaffolds. The cell constructs were cultured for 4 days to evaluate viability and morphology before implantation. Light microscopy revealed that within 2 to 3 days in culture, the dissociated cardiac cells form distinctive, multicellular contracting aggregates within the scaffold pores. Seven days after myocardial infarction, rats were randomized to biograft implantation (n=6) or sham-operation (n=6) into the myocardial scar. Echocardiography study was performed before and 65±5 days after implantation to assess left ventricular (LV) remodeling and function. Hearts were harvested 9 weeks after implantation. Visual examination of the biograft revealed intensive neovascularization from the neighboring coronary network. Histological examination revealed the presence of myofibers embedded in collagen fibers and a large number of blood vessels. The specimens showed almost complete disappearance of the scaffold and good integration into the host. Although control animals developed significant LV dilatation accompanied by progressive deterioration in LV contractility, in the biograft-treated rats, attenuation of LV dilatation and no change in LV contractility were observed. Conclusions —Alginate scaffolds provide a conducive environment to facilitate the 3D culturing of cardiac cells. After implantation into the infarcted myocardium, the biografts stimulated intense neovascularization and attenuated LV dilatation and failure in experimental rats compared with controls. This strategy can be used for regeneration and healing of the infarcted myocardium.

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Abstract 1552: Cardioplegic Arrest And Subsequent Reperfusion Induce Urocortin Expression In Non-apoptotic Cardiac Cells Selectively Associated With Mitochondrial Relocation Of PKCϵ

Circulation ◽

10.1161/circ.116.suppl_16.ii_322-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Carol Chen-Scarabelli ◽

Zhaokan Yuan ◽

Giuseppe Faggian ◽

Francesco Santini ◽

Alessio Rungatscher ◽

...

Keyword(s):

Western Blotting ◽

Internal Control ◽

Isolated Heart ◽

Ischemia Reperfusion ◽

Artery Bypass ◽

Fold Increase ◽

Cardiac Cells ◽

Image Analyzer ◽

Cardioplegic Arrest ◽

Mitochondrial Fractions

BACKGROUND: Cardioplegic arrest and subsequent reperfusion inevitably expose the heart to an iatrogenic ischemia/reperfusion injury (iIRI). We previously reported that iIRI caused mitochondria-initiated myocyte apoptosis, but also induction of urocortin (Ucn), an endogenous cardioprotective peptide. We also showed that Ucn induced PKCϵ-mediated opening of mitochondrial K ATP channels in isolated heart mitochondria. AIM: To investigate, in patients exposed to iIRI, the cardioprotective role and the mechanism of action of Ucn, with respect to PKCϵ expression, activation and relocation. METHODS AND RESULTS: Two sequential biopsies were obtained from the right atrium of 25 patients undergoing coronary artery bypass grafting at the start of grafting (internal control) and 10 mins after release of the aortic clamp. Mean values of ejection fraction, aortic cross-clamping time and number of grafts were 51±8; 48±8 mins; and 3.6±0.5 respectively. In hearts exposed to iIRI, RT-PCR and immunostaining showed Ucn induction at the mRNA (255% of basic levels, p<0.05) and protein level (28±2.1% positive myocytes vs 3.1±0.6% of internal control; p<0.01) respectively. iIRI also induced a selective increase of PKC-ϵ mRNA (225% of internal control; p<0.05) and a two-fold overexpression of total PKCϵ isoform (assessed by Western blotting; p<0.05), which paralleled a 2.9 fold increase in PKCϵ phosphorylation (p<0.01). TUNEL positivity (<0.1% and 2.9±0.7% positive myocytes pre- and post-iIRI respectively; p<0.01) was only seen in Ucn-negative cells, and, of note, Ucn-positive myocytes showed concurrent mitochondrial relocation of phosphorylated PKCϵ, as documented by mitochondrial-activated PKCϵ colocalization, calculated by confocal microscopy with an image analyzer software (% overlap: 57±5 vs 11±2 in Ucn-negative cells; p<0.01). Western blotting carried out in pools of cytosolic and mitochondrial fractions confirmed a 2.5 fold increase in mitochondrial localization of phosphorylated PKC-ϵ following iIRI (p<0.05). CONCLUSIONS : In patients exposed to iIRI, Ucn expression in viable cells was selectively associated with phosphorylation and mitochondrial relocation of PKCϵ, suggesting a cardioprotective role for endogenous Ucn in the human heart.

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Anti remodeling therapy: new strategies and future perspective in post-ischemic heart failure. Part II

Monaldi Archives for Chest Disease ◽

10.4081/monaldi.2014.64 ◽

2015 ◽

Vol 82 (4) ◽

Cited By ~ 2

Author(s):

Andrea Salzano ◽

Domenico Sirico ◽

Michele Arcopinto ◽

Alberto Maria Marra ◽

Germano Guerra ◽

...

Keyword(s):

Heart Failure ◽

Stem Cells ◽

Cardiac Tissue ◽

Cell Types ◽

Micro Rna ◽

Future Perspective ◽

Post Translational Modification ◽

Progression Of Disease ◽

Remarkable Progress ◽

New Strategies

In recent years, the remarkable progress achieved in terms of survival after myocardial infarction have led to an increased incidence of chronic heart failure in survivors. This phenomenon is due to the still incomplete knowledge we possess about the complex pathophysiological mechanisms that regulate the response of cardiac tissue to ischemic injury. These involve various cell types such as fibroblasts, cells of the immune system, endothelial cells, cardiomyocytes and stem cells, as well as a myriad of mediators belonging to the system of cytokines and not only. In parallel with the latest findings on post-infarct remodeling, new potential therapeutic targets are arising to halt the progression of disease. After the evaluation of the results obtained from gene therapy and stem cells, in this part we evaluate micro- RNA, post-translational modification and microspheres based therapy.

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Electrophysiological heterogeneity and stability of reentry in simulated cardiac tissue

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.280.2.h535 ◽

2001 ◽

Vol 280 (2) ◽

pp. H535-H545 ◽

Cited By ~ 57

Author(s):

Fagen Xie ◽

Zhilin Qu ◽

Alan Garfinkel ◽

James N. Weiss

Keyword(s):

Action Potential ◽

Action Potential Duration ◽

Cardiac Tissue ◽

Potential Model ◽

Dynamic Instability ◽

Spatial Scales ◽

Cardiac Cells ◽

Dynamic Factors ◽

Cardiac Model ◽

Wave Break

Generation of wave break is a characteristic feature of cardiac fibrillation. In this study, we investigated how dynamic factors and fixed electrophysiological heterogeneity interact to promote wave break in simulated two-dimensional cardiac tissue, by using the Luo-Rudy (LR1) ventricular action potential model. The degree of dynamic instability of the action potential model was controlled by varying the maximal amplitude of the slow inward Ca2+ current to produce spiral waves in homogeneous tissue that were either nearly stable, meandering, hypermeandering, or in breakup regimes. Fixed electrophysiological heterogeneity was modeled by randomly varying action potential duration over different spatial scales to create dispersion of refractoriness. We found that the degree of dispersion of refractoriness required to induce wave break decreased markedly as dynamic instability of the cardiac model increased. These findings suggest that reducing the dynamic instability of cardiac cells by interventions, such as decreasing the steepness of action potential duration restitution, may still have merit as an antifibrillatory strategy.

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Nanoengineering in Cardiac Regeneration: Looking Back and Going Forward

Nanomaterials ◽

10.3390/nano10081587 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1587

Author(s):

Caterina Cristallini ◽

Emanuela Vitale ◽

Claudia Giachino ◽

Raffaella Rastaldo

Keyword(s):

Tissue Engineering ◽

Experimental Study ◽

Extracellular Matrix ◽

Regenerative Medicine ◽

Cardiac Tissue ◽

Cardiac Regeneration ◽

Cardiac Cells ◽

Integration Process ◽

Specific Interest ◽

Looking Back

To deliver on the promise of cardiac regeneration, an integration process between an emerging field, nanomedicine, and a more consolidated one, tissue engineering, has begun. Our work aims at summarizing some of the most relevant prevailing cases of nanotechnological approaches applied to tissue engineering with a specific interest in cardiac regenerative medicine, as well as delineating some of the most compelling forthcoming orientations. Specifically, this review starts with a brief statement on the relevant clinical need, and then debates how nanotechnology can be combined with tissue engineering in the scope of mimicking a complex tissue like the myocardium and its natural extracellular matrix (ECM). The interaction of relevant stem, precursor, and differentiated cardiac cells with nanoengineered scaffolds is thoroughly presented. Another correspondingly relevant area of experimental study enclosing both nanotechnology and cardiac regeneration, e.g., nanoparticle applications in cardiac tissue engineering, is also discussed.

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