HUMAN iPSC ENGINEERED CARDIAC TISSUE PLATFORM FAITHFULLY MODELS IMPORTANT CARDIAC PHYSIOLOGY

2021 ◽  
Author(s):  
Willem J. de Lange ◽  
Emily T. Farrell ◽  
Caroline R. Kreitzer ◽  
Derek R. Jacobs ◽  
Di Lang ◽  
...  
Keyword(s):  
Cardiac Tissue ◽  
Human Myocardium ◽  
Protein Isoforms ◽  
Calcium Handling ◽  
Unintended Effects ◽  
Cardiac Physiology ◽  
Adrenergic Stimulation ◽  
Cardiac Model ◽  
Short Period ◽  
Tubular System

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) may provide an important bridge between animal models and intact human myocardium. Fulfilling this potential is hampered by their relative immaturity. hiPSC-CMs grown in monolayer culture lack a t-tubular system, have rudimentary intracellular calcium-handling systems, express predominantly embryonic sarcomeric protein isoforms, and preferentially use glucose as energy substrate. Culturing hiPSC-CM in a 3D environment and the addition of nutritional, pharmacologic and electromechanical stimuli have proven to be beneficial for maturation. We present an assessment of a model in which hiPSC-CMs and hiPSC-derived cardiac fibroblasts are co-cultured in a 3D fibrin matrix to form human engineered cardiac tissue constructs (hECT).The hECT respond to physiological stimuli, including stretch, frequency and β-adrenergic stimulation, develop a t-tubular system, and demonstrate calcium-handling and contractile kinetics that compare favorably with ventricular human myocardium. Transcript levels of genes involved in calcium-handling and contraction are increased. These markers of maturation become more robust over a short period of time in culture (6 weeks vs. 2 weeks in hECT). A comparison of the hECT molecular and performance variables with those of human cardiac tissue and other available engineered tissue platforms is provided to highlight strengths and weaknesses of these preparations. Important and noteworthy aspects of this human cardiac model system are its reliance on 'off-the-shelf' equipment, ability to provide detailed physiological performance data, and the ability to achieve a relatively mature cardiac physiology without additional nutritional, pharmacological and electromechanical stimuli that may elicit unintended effects on function.

scholarly journals Impact of site-specific phosphorylation of protein kinase A sites Ser23 and Ser24 of cardiac troponin I in human cardiomyocytes

2013 ◽  
Vol 304 (2) ◽  
pp. H260-H268 ◽  
Author(s):  
Paul J. M. Wijnker ◽  
D. Brian Foster ◽  
Allison L. Tsao ◽  
Aisha H. Frazier ◽  
Cristobal G. dos Remedios ◽  
...  
Keyword(s):  
Cardiac Troponin ◽  
Cardiac Tissue ◽  
Troponin I ◽  
Human Myocardium ◽  
Site Directed Mutagenesis ◽  
Adrenergic Stimulation ◽  
Human Cardiomyocytes ◽  
Health And Disease ◽  
Human Cardiac Tissue

PKA-mediated phosphorylation of contractile proteins upon β-adrenergic stimulation plays an important role in the regulation of cardiac performance. Phosphorylation of the PKA sites (Ser23/Ser24) of cardiac troponin (cTn)I results in a decrease in myofilament Ca2+ sensitivity and an increase in the rate of relaxation. However, the relation between the level of phosphorylation of the sites and the functional effects in the human myocardium is unknown. Therefore, site-directed mutagenesis was used to study the effects of phosphorylation at Ser23 and Ser24 of cTnI on myofilament function in human cardiac tissue. Serines were replaced by aspartic acid (D) or alanine (A) to mimic phosphorylation and dephosphorylation, respectively. cTnI-DD mimics both sites phosphorylated, cTnI-AD mimics Ser23 unphosphorylated and Ser24 phosphorylated, cTnI-DA mimics Ser23 phosphorylated and Ser24 unphosphorylated, and cTnI-AA mimics both sites unphosphorylated. Force development was measured at various Ca2+ concentrations in permeabilized cardiomyocytes in which the endogenous troponin complex was exchanged with these recombinant human troponin complexes. In donor cardiomyocytes, myofilament Ca2+ sensitivity (pCa50) was significantly lower in cTnI-DD (pCa50: 5.39 ± 0.01) compared with cTnI-AA (pCa50: 5.50 ± 0.01), cTnI-AD (pCa50: 5.48 ± 0.01), and cTnI-DA (pCa50: 5.51 ± 0.01) at ∼70% cTn exchange. No effects were observed on the rate of tension redevelopment. In cardiomyocytes from idiopathic dilated cardiomyopathic tissue, a linear decline in pCa50 with cTnI-DD content was observed, saturating at ∼55% bisphosphorylation. Our data suggest that in the human myocardium, phosphorylation of both PKA sites on cTnI is required to reduce myofilament Ca2+ sensitivity, which is maximal at ∼55% bisphosphorylated cTnI. The implications for in vivo cardiac function in health and disease are detailed in the discussion in this article.

scholarly journals Spontaneous calcium release in tissue from the failing canine heart

2009 ◽  
Vol 297 (4) ◽  
pp. H1235-H1242 ◽  
Author(s):  
Gregory S. Hoeker ◽  
Rodolphe P. Katra ◽  
Lance D. Wilson ◽  
Bradley N. Plummer ◽  
Kenneth R. Laurita
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Tissue Level ◽  
Calcium Handling ◽  
Canine Heart ◽  
Myocardial Cells ◽  
Spontaneous Release ◽  
Adrenergic Stimulation ◽  
Electrical Instability ◽  
Delayed Afterdepolarization

Abnormalities in calcium handling have been implicated as a significant source of electrical instability in heart failure (HF). While these abnormalities have been investigated extensively in isolated myocytes, how they manifest at the tissue level and trigger arrhythmias is not clear. We hypothesize that in HF, triggered activity (TA) is due to spontaneous calcium release from the sarcoplasmic reticulum that occurs in an aggregate of myocardial cells (an SRC) and that peak SCR amplitude is what determines whether TA will occur. Calcium and voltage optical mapping was performed in ventricular wedge preparations from canines with and without tachycardia-induced HF. In HF, steady-state calcium transients have reduced amplitude [135 vs. 170 ratiometric units (RU), P < 0.05] and increased duration (252 vs. 229 s, P < 0.05) compared with those of normal. Under control conditions and during β-adrenergic stimulation, TA was more frequent in HF (53% and 93%, respectively) compared with normal (0% and 55%, respectively, P < 0.025). The mechanism of arrhythmias was SCRs, leading to delayed afterdepolarization-mediated triggered beats. Interestingly, the rate of SCR rise was greater for events that triggered a beat (0.41 RU/ms) compared with those that did not (0.18 RU/ms, P < 0.001). In contrast, there was no difference in SCR amplitude between the two groups. In conclusion, TA in HF tissue is associated with abnormal calcium regulation and mediated by the spontaneous release of calcium from the sarcoplasmic reticulum in aggregates of myocardial cells (i.e., an SCR), but importantly, it is the rate of SCR rise rather than amplitude that was associated with TA.

scholarly journals Influence of Egr-1 in Cardiac Tissue-Derived Mesenchymal Stem Cells in Response to Glucose Variations

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Daniela Bastianelli ◽  
Camilla Siciliano ◽  
Rosa Puca ◽  
Andrea Coccia ◽  
Colin Murdoch ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Target Genes ◽  
Cardiac Tissue ◽  
Early Response ◽  
Induced Response ◽  
Protein Levels ◽  
Short Period ◽  
Phenotype Analysis

Mesenchymal stem cells (MSCs) represent a promising cell population for cell therapy and regenerative medicine applications. However, how variations in glucose are perceived by MSC pool is still unclear. Since, glucose metabolism is cell type and tissue dependent, this must be considered when MSCs are derived from alternative sources such as the heart. The zinc finger transcription factor Egr-1 is an important early response gene, likely to play a key role in the glucose-induced response. Our aim was to investigate how short-term changes inin vitroglucose concentrations affect multipotent cardiac tissue-derived MSCs (cMSCs) in a mouse model of Egr-1 KO (Egr-1−/−). Results showed that loss of Egr-1 does not significantly influence cMSC proliferation. In contrast, responses to glucose variations were observed in wt but not in Egr-1−/−cMSCs by clonogenic assay. Phenotype analysis by RT-PCR showed that cMSCs Egr-1−/−lost the ability to regulate the glucose transporters GLUT-1 and GLUT-4 and, as expected, the Egr-1 target genes VEGF, TGFβ-1, and p300. Acetylated protein levels of H3 histone were impaired in Egr-1−/−compared to wt cMSCs. We propose that Egr-1 acts as immediate glucose biological sensor in cMSCs after a short period of stimuli, likely inducing epigenetic modifications.

Decrease Tyrosine Phosphorylation of Stat3 in Human Myocardium with End-Stage Congestive Heart Failure

2000 ◽  
Vol 6 (S2) ◽  
pp. 596-597
Author(s):  
C. Wei ◽  
J. S. McLaughlin
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Protein Expression ◽  
Cardiac Tissue ◽  
Normal Subjects ◽  
Human Myocardium ◽  
Stat3 Phosphorylation ◽  
Normal Human ◽  
Human Cardiac Tissue ◽  
End Stage

Recent study demonstrated that decrease signal transducer and activator of transcription-3 (STAT3) phosphorylation and increase apoptosis might be a critical point in the transition between compensatory cardiac hypertrophy and heart failure. To date, the protein expression of STAT3 in normal and failing human heart remains unclear. Therefore, the current study was designed to investigate the protein expression of STAT3 in human myocardium with end-stage congestive heart failure (CHF) and compared with that in normal human cardiac tissue.Human cardiac atrial tissue was obtained from normal subjects (n=5) and end-stage CHF patients (n=5) during cardiac transplantation. To detect the DNA fragmentation, in situ terminal deoxymucleotidyl transferase dUTP nick end labeling (TUNEL) was performed. An average of 1000 nuclei was analyzed for TUNEL study. STAT3 protein expression and phosphorylation of STAT3 were determined by immunohistochemical staining (IHCS) with total STAT3 and phospho-specific STAT3 antibodies.

Enhancement of Endothelin Converting Enzyme and Endothelin Receptor Subtypes in Human Myocardium with Congestive Heart Failure

2000 ◽  
Vol 6 (S2) ◽  
pp. 608-609
Author(s):  
J. Lin ◽  
C Wei
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Cardiac Tissue ◽  
Vascular Endothelial Cells ◽  
Normal Subjects ◽  
Human Myocardium ◽  
Endothelin Receptors ◽  
Receptor Subtypes ◽  
Converting Enzyme ◽  
Endothelin Converting Enzyme

Endothelin-1 (ET-1) is a potent endothelial cell-drived vasoconstrictive peptide which is increased in congestive heart failure (CHF). ET-1 is converted from its precursor big ET-1 by activation of endothelin converting enzyme (ECE). ET-1 binding to ET-A receptor in vascular smooth muscle cells stimulates vasoconstriction and binding to ET-B receptor in vascular endothelial cells mediates vasodilation. In previous studies, we and others demonstrated that plasma ET-1 was significantly increased in congestive heart failure. However, the presentation and localization of endothelin converting enzyme and endothelin receptors (ET-A and ET-B) in human cardiac tissue with and without heart failure remain unclear. Therefore, the current study was designed to investigate the expression and localization of endothelin receptors and endothelin converting enzyme in human myocardium in the absence or presence of congestive heart failure.Human atrial tissues (n=6) were obtained from normal subjects and end-stage CHF patients during cardiac transplantation. The expression of ECE, ET-A and ET-B were determined by immunohistochemical staining (IHCS).

Electrophysiological heterogeneity and stability of reentry in simulated cardiac tissue

2001 ◽  
Vol 280 (2) ◽  
pp. H535-H545 ◽  
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.

scholarly journals Heart Failure Differentially Modulates Natural (Sinoatrial Node) and Ectopic (Pulmonary Veins) Pacemakers: Mechanism and Therapeutic Implication for Atrial Fibrillation

2019 ◽  
Vol 20 (13) ◽  
pp. 3224 ◽  
Author(s):  
Chao-Shun Chan ◽  
Yung-Kuo Lin ◽  
Yao-Chang Chen ◽  
Yen-Yu Lu ◽  
Shih-Ann Chen ◽  
...  
Keyword(s):  
Heart Failure ◽  
Atrial Fibrillation ◽  
Electrical Activity ◽  
Sinoatrial Node ◽  
Sick Sinus Syndrome ◽  
Pulmonary Veins ◽  
Calcium Handling ◽  
Adrenergic Stimulation ◽  
Therapeutic Implications ◽  
Cardiac Filling

Heart failure (HF) frequently coexists with atrial fibrillation (AF) and dysfunction of the sinoatrial node (SAN), the natural pacemaker. HF is associated with chronic adrenergic stimulation, neurohormonal activation, abnormal intracellular calcium handling, elevated cardiac filling pressure and atrial stretch, and fibrosis. Pulmonary veins (PVs), which are the points of onset of ectopic electrical activity, are the most crucial AF triggers. A crosstalk between the SAN and PVs determines PV arrhythmogenesis. HF has different effects on SAN and PV electrophysiological characteristics, which critically modulate the development of AF and sick sinus syndrome. This review provides updates to improve our current understanding of the effects of HF in the electrical activity of the SAN and PVs as well as therapeutic implications for AF.

Expression of Angiotensin II Type 1 and Type 2 Receptor in Human Myocardium with Congestive Heart Failure

2000 ◽  
Vol 6 (S2) ◽  
pp. 618-619
Author(s):  
P. Y. Lau ◽  
M. G. Cardarelli ◽  
C. Wei
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Angiotensin Ii ◽  
Cardiac Tissue ◽  
Open Heart Surgery ◽  
Human Myocardium ◽  
Receptor Expression ◽  
At2 Receptors

Angiotensin II (AH) is a potent vasoconstrictor and mitogenic factor. AH receptors include type 1 (ATI) and type 2 (AT2) receptors. Recent studies demonstrated that both ATI and AT2 receptors expressed in human myocardium. Circulating and local tissue level of AH was increased in severe congestive heart failure (CHF). However, the expression of ATI and AT2 in cardiac tissue with CHF remains controversial. Therefore, the present study was designed to investigate the protein expression of ATI and AT2 receptors in normal human myocardium and in human cardiac tissue with mild and severe CHF.Human atrial tissues from normal subjects and CHF patients with ischemic cardiomyopathy and dilated cardiomyopathy were obtained from open-heart surgery and cardiac transplantation. ATI and AT2 receptor expression was investigated by immunohistochemical staining (IHCS). The results of IHCS was evaluated by IHCS staining density scores (0, no staining; 1, minimal staining; 2, mild staining; 3, moderate staining; and 4, strong staining).

scholarly journals Deep Characterization of Circular RNAs from Human Cardiovascular Cell Models and Cardiac Tissue

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1616
Author(s):  
Tobias Jakobi ◽  
Dominik Siede ◽  
Jessica Eschenbach ◽  
Andreas W. Heumüller ◽  
Martin Busch ◽  
...  
Keyword(s):  
Cardiac Tissue ◽  
Umbilical Vein ◽  
Expression Profiles ◽  
Developed Countries ◽  
Model Systems ◽  
Start Codon ◽  
Circular Rnas ◽  
Specific Expression ◽  
Cardiac Model ◽  
Depth Analysis

For decades, cardiovascular disease (CVD) has been the leading cause of death throughout most developed countries. Several studies relate RNA splicing, and more recently also circular RNAs (circRNAs), to CVD. CircRNAs originate from linear transcripts and have been shown to exhibit tissue-specific expression profiles. Here, we present an in-depth analysis of sequence, structure, modification, and cardiac circRNA interactions. We used human induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CMs), human healthy and diseased (ischemic cardiomyopathy, dilated cardiomyopathy) cardiac tissue, and human umbilical vein endothelial cells (HUVECs) to profile circRNAs. We identified shared circRNAs across all samples, as well as model-specific circRNA signatures. Based on these circRNAs, we identified 63 positionally conserved and expressed circRNAs in human, pig, and mouse hearts. Furthermore, we found that the sequence of circRNAs can deviate from the sequence derived from the genome sequence, an important factor in assessing potential functions. Integration of additional data yielded evidence for m6A-methylation of circRNAs, potentially linked to translation, as well as, circRNAs overlapping with potential Argonaute 2 binding sites, indicating potential association with the RISC complex. Moreover, we describe, for the first time in cardiac model systems, a sub class of circRNAs containing the start codon of their primary transcript (AUG circRNAs) and observe an enrichment for m6A-methylation for AUG circRNAs.

Ryanodine receptor dysfunction and triggered activity in the heart

2007 ◽  
Vol 292 (5) ◽  
pp. H2144-H2151 ◽  
Author(s):  
Rodolphe P. Katra ◽  
Toshiyuki Oya ◽  
Gregory S. Hoeker ◽  
Kenneth R. Laurita
Keyword(s):  
Ryanodine Receptor ◽  
Transmembrane Potential ◽  
Calcium Release ◽  
Left Ventricular ◽  
Calcium Handling ◽  
Adrenergic Stimulation ◽  
Triggered Activity ◽  
Multiple Regions ◽  
Rapid Pacing ◽  
Almost All

Arrhythmogenesis has been increasingly linked to cardiac ryanodine receptor (RyR) dysfunction. However, the mechanistic relationship between abnormal RyR function and arrhythmogenesis in the heart is not clear. We hypothesize that, under abnormal RyR conditions, triggered activity will be caused by spontaneous calcium release (SCR) events that depend on transmural heterogeneities of calcium handling. We performed high-resolution optical mapping of intracellular calcium and transmembrane potential in the canine left ventricular wedge preparation ( n = 28). Rapid pacing was used to initiate triggered activity under normal and abnormal RyR conditions induced by FKBP12.6 dissociation and β-adrenergic stimulation (20–150 μM rapamycin, 0.2 μM isoproterenol). Under abnormal RyR conditions, almost all preparations experienced SCRs and triggered activity, in contrast to control, rapamycin, or isoproterenol conditions alone. Furthermore, under abnormal RyR conditions, complex arrhythmias (monomorphic and polymorphic tachycardia) were commonly observed. After washout of rapamycin and isoproterenol, no triggered activity was observed. Surprisingly, triggered activity and SCRs occurred preferentially near the epicardium but not the endocardium ( P < 0.01). Interestingly, the occurrence of triggered activity and SCR events could not be explained by cytoplasmic calcium levels, but rather by fast calcium reuptake kinetics. These data suggest that, under abnormal RyR conditions, triggered activity is caused by multiple SCR events that depend on the faster calcium reuptake kinetics near the epicardium. Furthermore, multiple regions of SCR may be a mechanism for multifocal arrhythmias associated with RyR dysfunction.

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