scholarly journals Cardiomyocyte Na+ and Ca2+ mishandling drives vicious cycle involving CaMKII, ROS, and ryanodine receptors

2021 ◽  
Vol 116 (1) ◽  
Author(s):  
Bence Hegyi ◽  
Risto-Pekka Pölönen ◽  
Kim T. Hellgren ◽  
Christopher Y. Ko ◽  
Kenneth S. Ginsburg ◽  
...  
Keyword(s):  
Heart Diseases ◽  
Ryanodine Receptors ◽  
Induced Pluripotent Stem Cell ◽  
Polymorphic Ventricular Tachycardia ◽  
Vicious Cycle ◽  
Ros Scavenging ◽  
Early Afterdepolarizations ◽  
Mitochondrial Ros ◽  
Critical Components ◽  
Induced Pluripotent

AbstractCardiomyocyte Na+ and Ca2+ mishandling, upregulated Ca2+/calmodulin-dependent kinase II (CaMKII), and increased reactive oxygen species (ROS) are characteristics of various heart diseases, including heart failure (HF), long QT (LQT) syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT). These changes may form a vicious cycle of positive feedback to promote cardiac dysfunction and arrhythmias. In HF rabbit cardiomyocytes investigated in this study, the inhibition of CaMKII, late Na+ current (INaL), and leaky ryanodine receptors (RyRs) all attenuated the prolongation and increased short-term variability (STV) of action potential duration (APD), but in age-matched controls these inhibitors had no or minimal effects. In control cardiomyocytes, we enhanced RyR leak (by low [caffeine] plus isoproterenol mimicking CPVT) which markedly increased STV and delayed afterdepolarizations (DADs). These proarrhythmic changes were significantly attenuated by both CaMKII inhibition and mitochondrial ROS scavenging, with a slight synergy with INaL inhibition. Inducing LQT by elevating INaL (by Anemone toxin II, ATX-II) caused markedly prolonged APD, increased STV, and early afterdepolarizations (EADs). Those proarrhythmic ATX-II effects were largely attenuated by mitochondrial ROS scavenging, and partially reduced by inhibition of CaMKII and pathological leaky RyRs using dantrolene. In human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) bearing LQT3 mutation SCN5A N406K, dantrolene significantly attenuated cell arrhythmias and APD prolongation. Targeting critical components of the Na+–Ca2+–CaMKII–ROS–INaL arrhythmogenic vicious cycle may exhibit important on-target and also trans-target effects (e.g., INaL and RyR inhibition can alter INaL-mediated LQT3 effects). Incorporating this vicious cycle into therapeutic strategies provides novel integrated insight for treating cardiac arrhythmias and diseases.

scholarly journals Mutation-specific differences in arrhythmias and drug responses in CPVT patients: simultaneous patch clamp and video imaging of iPSC derived cardiomyocytes

2019 ◽  
Vol 47 (2) ◽  
pp. 1067-1077 ◽  
Author(s):  
R. P. Pölönen ◽  
H. Swan ◽  
K. Aalto-Setälä
Keyword(s):  
Disease Modeling ◽  
Induced Pluripotent Stem Cell ◽  
Polymorphic Ventricular Tachycardia ◽  
Patient Specific ◽  
Electrophysiological Properties ◽  
Electrophysiological Measurements ◽  
Skin Biopsies ◽  
Induced Pluripotent ◽  
Almost All ◽  
And Control

AbstractCatecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease characterized by arrhythmias under adrenergic stress. Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for CPVT. We characterized electrophysiological properties of CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) carrying different mutations in RYR2 and evaluated effects of carvedilol and flecainide on action potential (AP) and contractile properties of hiPSC-CMs. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion (E3D) and L4115F mutation in RYR2. APs and contractile movement were recorded simultaneously from the same hiPSC-CMs. Differences in AP properties of ventricular like CMs were seen in CPVT and control CMs: APD90 of both E3D (n = 20) and L4115F (n = 25) CPVT CMs was shorter than in control CMs (n = 15). E3D-CPVT CMs had shortest AP duration, lowest AP amplitude, upstroke velocity and more depolarized diastolic potential than controls. Adrenaline had positive and carvedilol and flecainide negative chronotropic effect in all hiPSC CMs. CPVT CMs had increased amount of delayed after depolarizations (DADs) and early after depolarizations (EADs) after adrenaline exposure. E3D CPVT CMs had the most DADs, EADs, and tachyarrhythmia. Discordant negatively coupled alternans was seen in L4115F CPVT CMs. Carvedilol cured almost all arrhythmias in L4115F CPVT CMs. Both drugs decreased contraction amplitude in all hiPSC CMs. E3D CPVT CMs have electrophysiological properties, which render them more prone to arrhythmias. iPSC-CMs provide a unique platform for disease modeling and drug screening for CPVT. Combining electrophysiological measurements, we can gain deeper insight into mechanisms of arrhythmias.

Abstract 15566: Induced Pluripotent Stem Cell-Derived Cardiomyocytes Recapitulate Clinically Observed Refractoriness to Therapeutic β-Blockade in a Patient-Specific Model of Catecholaminergic Polymorphic Ventricular Tachycardia

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Marcela K Preininger ◽  
Rajneesh Jha ◽  
Qingling Wu ◽  
Monalisa Singh ◽  
Joshua T Maxwell ◽  
...  
Keyword(s):  
Stem Cell ◽  
Ventricular Tachycardia ◽  
Pluripotent Stem Cell ◽  
Induced Pluripotent Stem Cell ◽  
Polymorphic Ventricular Tachycardia ◽  
Patient Specific ◽  
Blocker Therapy ◽  
Β Blocker ◽  
Induced Pluripotent

Introduction: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome characterized by diastolic store overload-induced Ca2+ waves during β-adrenergic receptor (β-AR) stimulation. Mysteriously, β-blockers are ineffective at abolishing stress-induced ventricular arrhythmias in ~25% of patients. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from these CPVT patients offer an attractive system for investigating the phenomenon, but it remains unknown whether iPSC-CMs can recapitulate clinically observed patient-specific drug responses. Hypothesis: This study assessed the hypothesis that patient-specific refractoriness to β-blocker therapy can be observed in vitro using CPVT iPSC-CMs. Methods: We generated iPSC-CMs from a control individual and a CPVT patient insensitive to the widely prescribed β-blocker nadolol, but responsive to flecainide, and compared the efficacy of the two drugs in vitro in diminishing diastolic Ca2+ waves and restoring Ca2+ spark parameters during β-AR stimulation. Results: In CPVT hiPSC-CMs (n = 34), β-AR agonism elicited intense diastolic Ca2+ waves and potentiated unduly frequent, large, and prolonged Ca2+ sparks compared to control iPSC-CMs (n = 12). Pursuant to the patient’s in vivo responses, nadolol-treated CPVT iPSC-CMs (n = 27) demonstrated inadequate improvement of Ca2+ handling defects during β-AR stimulation relative to flecainide-treated CPVT iPSC-CMs (n = 25). Nadolol showed no significant effect on the frequency of diastolic Ca2+ waves, but reduced mean amplitude by 50% (p < 0.0001). In contrast, flecainide reduced both frequency and amplitude by 83% (p < 0.001) and 72% (p < 0.0001), respectively. During nadolol treatment, Ca2+ spark frequency, width, and duration remained significantly altered, while flecainide restored all Ca2+ spark parameters to baseline levels. Conclusions: Clinically observed recalcitrance to β-blocker therapy in individuals with CPVT can be modeled in vitro using patient-derived iPSC-CMs. Furthermore, the efficacy of other drugs such as flecainide can be comparatively evaluated, supporting the use of patient-specific iPSC-CMs as a clinically-relevant implement of precision medicine.

Abstract 17205: Contractility in Human Induced Pluripotent Stem Cell Derived Cardiomyocytes is Highly Dependent on Stochastic Variability in Myofilament Development

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Jonathan Hernandez ◽  
Akul Arora ◽  
Kathryn Ufford ◽  
Sabrina Friedline ◽  
Zhaowen Tong ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Heart Diseases ◽  
Control Cell ◽  
Traction Force ◽  
Induced Pluripotent Stem Cell ◽  
Live Cell ◽  
Maximum Force ◽  
Critical Determinant ◽  
Induced Pluripotent

Introduction: Modeling heart diseases using cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) enables direct study of cellular and molecular mechanisms. However, the variable phenotypes of individual cells has limited the reproducibility of contractile measurements. We hypothesized that variability in myofibrillar development in hiPSC-CMs influences the contractile kinetics and could be controlled for by visualizing and quantifying myofilaments in vitro . Methods and Results: Control hiPSCs were differentiated into cardiomyocytes (hiPSC-CMs) and purified. hiPSC-CMs were replated at day ~25 onto 8.7 kPa polyacrylamide gels containing fluorescent microbeads and micropatterned with fibronectin in 7:1 aspect ratio rectangles (1750 um 2 ). Single iPSC-CMs grew into the rectangular shapes and exhibited spontaneous contractions by day 2 of replating. hiPSC-CMs were stained with live-cell actin dye and imaged on day 5-7 for fluorescent bead displacements and actin videos depicting myofilaments. Traction force analysis of bead displacements was performed to calculate whole-cell force vs. time curves at 33 msec temporal resolution. Myofilament area was measured by thresholding a binary mask on the actin live cell images. Myofilament number varied markedly among individual iPSC-CMs. iPSC-CMs with few myofilaments (myofilament area / cell area <30%) developed low force (<400 uN per cell) and were not included in subsequent analyses. Among cells with myofilament area >30%, the mean traction force was 1368±357 uN and the myofilament area demonstrated a linear correlation with maximum force (R 2 =0.19, runs test p=0.8) with slope of 0.8±0.2 uN/um 2 (p=0.002 vs zero slope). Maximum contraction velocity strongly correlated with maximum force (R 2 =0.31, runs test p=0.4) with slope of 3.9±0.9 sec -1 (p<0.0001 vs zero slope), as did maximum relaxation velocity (R 2 =0.27, runs test p=0.6, slope 4.1+1.0 sec -1 , p=0.0003 vs zero slope). Similar results were observed in two control cell lines and with two different purification methods. Conclusion: Variability in myofilament development is a critical determinant of contractile force and kinetics in individual iPSC-CMs that should be accounted for in iPSC-CM contractile experiments.

scholarly journals Drug Development and the Use of Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Disease Modeling and Drug Toxicity Screening

2020 ◽  
Vol 21 (19) ◽  
pp. 7320
Author(s):  
Paz Ovics ◽  
Danielle Regev ◽  
Polina Baskin ◽  
Mor Davidor ◽  
Yuval Shemer ◽  
...  
Keyword(s):  
Stem Cell ◽  
Drug Development ◽  
Drug Screening ◽  
Pluripotent Stem Cell ◽  
Disease Modeling ◽  
Heart Diseases ◽  
Induced Pluripotent Stem Cell ◽  
Drug Reactions ◽  
Novel Drugs ◽  
Induced Pluripotent

Over the years, numerous groups have employed human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) as a superb human-compatible model for investigating the function and dysfunction of cardiomyocytes, drug screening and toxicity, disease modeling and for the development of novel drugs for heart diseases. In this review, we discuss the broad use of iPSC-CMs for drug development and disease modeling, in two related themes. In the first theme—drug development, adverse drug reactions, mechanisms of cardiotoxicity and the need for efficient drug screening protocols—we discuss the critical need to screen old and new drugs, the process of drug development, marketing and Adverse Drug reactions (ADRs), drug-induced cardiotoxicity, safety screening during drug development, drug development and patient-specific effect and different mechanisms of ADRs. In the second theme—using iPSC-CMs for disease modeling and developing novel drugs for heart diseases—we discuss the rationale for using iPSC-CMs and modeling acquired and inherited heart diseases with iPSC-CMs.

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