Abstract P309: Particulate Matter Increases Oxidative Stress And Shortens The Action Potential In IPS-derived Cardiomyocytes

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Mariana Argenziano ◽  
jiajia yang ◽  
Mariana Burgos Angulo ◽  
Thomas V McDonald
Keyword(s):  
Oxidative Stress ◽  
Particulate Matter ◽  
Action Potential ◽  
Cardiac Electrophysiology ◽  
Structural Changes ◽  
Hospital Admissions ◽  
Induced Pluripotent Stem Cell ◽  
Toxic Substances ◽  
Direct Role ◽  
Atp Production

Introduction: Air particulate matter (PM) represents one of the most critical environmental issues worldwide, causing more than 3 million deaths a year. In the US, hospital admissions due to heart failure (HF) increase by 0.8% for every 10 μg/m3 elevation in PM. However, the biological mechanisms behind the effects of PM on cardiovascular disease (CVD) remain poorly defined. Recent studies showed that PM 2.5 can translocate into the circulation, causing cumulative toxicity. With air pollution increasing due to human activity and the growing prevalence of HF, there is a critical need to understand PM's contributions to CVD to develop preventive treatments and novel therapeutic approaches. Hypothesis: We hypothesize that PM can exert its toxic effect by increasing oxidative stress and apoptosis and affecting cardiac electrophysiology. Methods: Three independent induced pluripotent stem cell lines (IPSC) were differentiated into cardiomyocytes (iCMs) and cultured for 30 days before treatment with 100 μg/ml of PM 2.5 for 48h. Experiments including immunostaining, qPCR, RNAseq and Multielectrode Array (MEA) were performed in control (CT) and PM-treated iCMs (PM). Results: Treatment with PM increased ROS and decreased ATP production (CT 9.9±1.2pmol vs PM 6.6±0.8pmol, p<0.01, n=20). Immunostaining showed mitochondrial fragmentation and increased expression of cleaved caspase3 without structural changes. Moreover, PM caused upregulation of the apoptotic markers P53 , PARP1 and CASP3, oxidative stress markers CYP1A1, CYP1B1 and MT2A, and cardiac markers CACNA1C together with downregulation of GJA1 . RNAseq analysis showed upregulation of Gene Ontology terms related to detoxification, response to toxic substances and oxidative stress. Upregulated KEGG pathways included oxidative phosphorylation, hypertrophic cardiomyopathy and dilated cardiomyopathy. MEA experiments revealed a decrease in the spike amplitude and conduction velocity, along with shortening of the action potential (APD90: CT 577±20ms vs. PM 489±16ms, p<0.05, n=20) and increased beat period irregularity (CT 3.2±0.7% vs. PM 13.1±1.6%, p<0.001, n=20). These electrophysiological changes were reversed by treatment with the antioxidant N-acetylcysteine. Conclusions: We conclude that PM plays a direct role in the development of CVD, causing an increase in oxidative stress and affecting the electrophysiology of the heart. Further functional studies in iCMs from HF patients will provide evidence of the effects of these changes on the phenotype of the disease.

scholarly journals Contribution of two-pore K+ channels to cardiac ventricular action potential revealed using human iPSC-derived cardiomyocytes

2017 ◽  
Vol 312 (6) ◽  
pp. H1144-H1153 ◽  
Author(s):  
Sam Chai ◽  
Xiaoping Wan ◽  
Drew M. Nassal ◽  
Haiyan Liu ◽  
Christine S. Moravec ◽  
...  
Keyword(s):  
Action Potential ◽  
Expression Profile ◽  
Cardiac Electrophysiology ◽  
Human Heart ◽  
Induced Pluripotent Stem Cell ◽  
Heart Tissue ◽  
Induced Pluripotent ◽  
Interfering Rna ◽  
Human Ipsc ◽  
Physiological Systems

Two-pore K+ (K2p) channels have been described in modulating background conductance as leak channels in different physiological systems. In the heart, the expression of K2p channels is heterogeneous with equivocation regarding their functional role. Our objective was to determine the K2p expression profile and their physiological and pathophysiological contribution to cardiac electrophysiology. Induced pluripotent stem cells (iPSCs) generated from humans were differentiated into cardiomyocytes (iPSC-CMs). mRNA was isolated from these cells, commercial iPSC-CM (iCells), control human heart ventricular tissue (cHVT), and ischemic (iHF) and nonischemic heart failure tissues (niHF). We detected 10 K2p channels in the heart. Comparing quantitative PCR expression of K2p channels between human heart tissue and iPSC-CMs revealed K2p1.1, K2p2.1, K2p5.1, and K2p17.1 to be higher expressed in cHVT, whereas K2p3.1 and K2p13.1 were higher in iPSC-CMs. Notably, K2p17.1 was significantly lower in niHF tissues compared with cHVT. Action potential recordings in iCells after K2p small interfering RNA knockdown revealed prolongations in action potential depolarization at 90% repolarization for K2p2.1, K2p3.1, K2p6.1, and K2p17.1. Here, we report the expression level of 10 human K2p channels in iPSC-CMs and how they compared with cHVT. Importantly, our functional electrophysiological data in human iPSC-CMs revealed a prominent role in cardiac ventricular repolarization for four of these channels. Finally, we also identified K2p17.1 as significantly reduced in niHF tissues and K2p4.1 as reduced in niHF compared with iHF. Thus, we advance the notion that K2p channels are emerging as novel players in cardiac ventricular electrophysiology that could also be remodeled in cardiac pathology and therefore contribute to arrhythmias. NEW & NOTEWORTHY Two-pore K+ (K2p) channels are traditionally regarded as merely background leak channels in myriad physiological systems. Here, we describe the expression profile of K2p channels in human-induced pluripotent stem cell-derived cardiomyocytes and outline a salient role in cardiac repolarization and pathology for multiple K2p channels.

scholarly journals Absence of Functional Nav1.8 Channels in Non-diseased Atrial and Ventricular Cardiomyocytes

2019 ◽  
Vol 33 (6) ◽  
pp. 649-660 ◽  
Author(s):  
Simona Casini ◽  
Gerard A. Marchal ◽  
Makiri Kawasaki ◽  
Fransisca A. Nariswari ◽  
Vincent Portero ◽  
...  
Keyword(s):  
Action Potential ◽  
Cardiac Electrophysiology ◽  
Sodium Current ◽  
Association Studies ◽  
Induced Pluripotent Stem Cell ◽  
Cell Types ◽  
Left Ventricular ◽  
Resting Membrane Potential ◽  
Genome Wide Association Studies ◽  
Ventricular Cardiomyocytes

Abstract Purpose Several studies have indicated a potential role for SCN10A/NaV1.8 in modulating cardiac electrophysiology and arrhythmia susceptibility. However, by which mechanism SCN10A/NaV1.8 impacts on cardiac electrical function is still a matter of debate. To address this, we here investigated the functional relevance of NaV1.8 in atrial and ventricular cardiomyocytes (CMs), focusing on the contribution of NaV1.8 to the peak and late sodium current (INa) under normal conditions in different species. Methods The effects of the NaV1.8 blocker A-803467 were investigated through patch-clamp analysis in freshly isolated rabbit left ventricular CMs, human left atrial CMs and human-induced pluripotent stem cell-derived CMs (hiPSC-CMs). Results A-803467 treatment caused a slight shortening of the action potential duration (APD) in rabbit CMs and hiPSC-CMs, while it had no effect on APD in human atrial cells. Resting membrane potential, action potential (AP) amplitude, and AP upstroke velocity were unaffected by A-803467 application. Similarly, INa density was unchanged after exposure to A-803467 and NaV1.8-based late INa was undetectable in all cell types analysed. Finally, low to absent expression levels of SCN10A were observed in human atrial tissue, rabbit ventricular tissue and hiPSC-CMs. Conclusion We here demonstrate the absence of functional NaV1.8 channels in non-diseased atrial and ventricular CMs. Hence, the association of SCN10A variants with cardiac electrophysiology observed in, e.g. genome wide association studies, is likely the result of indirect effects on SCN5A expression and/or NaV1.8 activity in cell types other than CMs.

scholarly journals Oxidative Stress Measurement in Frozen/Thawed Human Sperm: The Protective Role of an In Vitro Treatment with Myo-Inositol

Antioxidants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 10
Author(s):  
Rosetta Ponchia ◽  
Annunziata Bruno ◽  
Asia Renzi ◽  
Claudia Landi ◽  
Enxhi Shaba ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Structural Changes ◽  
Stress Measurement ◽  
Sperm Quality ◽  
Human Sperm ◽  
2D Electrophoresis ◽  
Sperm Cryopreservation ◽  
Atp Production

Despite its widespread use, sperm cryopreservation induces serious detrimental alterations in sperm function; indeed, it is commonly associated with decreased sperm viability and motility, and DNA fragmentation. Mechanisms of human sperm cryodamage are thought to be multifactorial, but oxidative stress seems to have a prominent role. A huge amount of data supported the cryoprotective effect of different antioxidants able to minimize the detrimental effects of reactive oxygen species (ROS) and improve the quality of spermatozoa. Among others, myo-inositol is one of the most powerful and has been reported to be effective in improving sperm quality and motility when used both in vivo and in vitro. This study aimed to determine the in vitro impact of myo-inositol in ameliorating sperm oxidative status during sperm cryopreservation. In particular, we demonstrated a significant improvement of sperm parameters (vitality and motility) when myo-inositol was added after sperm thawing (p < 0.05). Moreover, we showed that myo-inositol induces a significant increase in oxygen consumption, the main index of oxidative phosphorylation efficiency and ATP production. Finally, by means of 2D-electrophoresis, we demonstrated a significant decrease in the level of carbonyl groups, the main structural changes occurring in conditions of oxidative stress (p < 0.05). In conclusion, the sperm cryopreservation procedure we developed, assuring the reduction of ROS-induced sperm modifications, may improve the in vitro procedure currently used in ART laboratory for sperm cryostorage.

scholarly journals Bioenergetic and metabolic impairments in Duchenne Muscular Dystrophy (DMD) patients' iPSC-derived cardiomyocytes

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
L Willi ◽  
B Agranovich ◽  
I Abramovich ◽  
D Freimark ◽  
M Arad ◽  
...  
Keyword(s):  
Stress Test ◽  
Young Male ◽  
Induced Pluripotent Stem Cell ◽  
Dystrophin Gene ◽  
Energy System ◽  
Basal Respiration ◽  
Mitochondrial Activity ◽  
Funding Source ◽  
Atp Production ◽  
Metabolic Impairments

Abstract Introduction DMD, an X-linked muscle degenerative fatal disease, is caused by mutations in the dystrophin gene. Dilated cardiomyopathy (DCM) is a major cause of morbidity and mortality in DMD patients. Treatments for DCM in DMD are limited to steroids and standard heart failure medications such as β-blockers and ACE-inhibitors, and therefore novel therapeutic modalities are urgently needed. Purpose We hypothesized that dystrophin mutations in DMD lead to cardiomyopathy-causing bioenergetic/metabolic impairments, which can be therapeutically targeted for improving cardiac function. Methods Induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CMs) were generated from healthy volunteer and 3 DMD patients: young male (YM), adult male (AM) and adult female (AF). We investigated the bioenergetics, electrophysiology, mitochondrial and metabolic features of healthy and DMD iPSC-CMs using the Seahorse Flux analyzer, patch clamp, confocal fluorescence microscopy and Liquid chromatography mass spectrometry (LC-MS) technologies, respectively. Results To test the hypothesis, we measured respiration and glycolytic rates of healthy and DMD iPSC-CMs. Compared to healthy iPSC-CMs, in both AM and AF DMD, but not in YM DMD cardiomyocytes, there was a 75% decrease in ATP production, and 80% and 45% decrease in basal respiration, respectively. In agreement with the healthy-like bioenergetic status of YM, the iPSC-CMs showed no arrhythmias, in contrast to the prominent arrhythmias in AM and AF cardiomyocytes. To determine whether the impairment in the phosphorylation pathway (OXPHOS) affects glycolysis, we measured the cardiomyocytes' response to glycolytic stress test. These experiments showed that the glycolytic rates were similar in healthy and DMD iPSC-CMs. In agreement with impaired OXPHOS, mitochondrial activity measured by 3D life confocal microscopy was attenuated in the DMD male by 35%, compared to healthy cardiomyocytes. Furthermore, the metabolomic LC-MS analyses demonstrated significant differences in metabolite levels in YM, AM and AF DMD iPSC-CMs relative to healthy iPSC-CMs. For example, compared to healthy iPSC-CMs, there was a dramatic fall to undetected levels in phosphocreatine in both AM and AF, but not in YM DMD, indicating a dysfunctional phosphocreatine energy system. Conclusions DMD iPSC-CMs exhibit bioenergetic/metabolic impairments, which constitute novel targets for alleviating the cardiomyopathy in DMD patients. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): ISF - Israel Science Foundation

scholarly journals Establishment of an in vitro model for analyzing mitochondrial ultrastructure in PRKN-mutated patient iPSC-derived dopaminergic neurons

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Mutsumi Yokota ◽  
Soichiro Kakuta ◽  
Takahiro Shiga ◽  
Kei-ichi Ishikawa ◽  
Hideyuki Okano ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dopaminergic Neurons ◽  
Structural Changes ◽  
In Vitro Model ◽  
Induced Pluripotent Stem Cell ◽  
Substantia Nigra Pars Compacta ◽  
Ultrastructural Changes ◽  
Mitochondrial Morphology ◽  
Vitro Model

AbstractMitochondrial structural changes are associated with the regulation of mitochondrial function, apoptosis, and neurodegenerative diseases. PRKN is known to be involved with various mechanisms of mitochondrial quality control including mitochondrial structural changes. Parkinson’s disease (PD) with PRKN mutations is characterized by the preferential degeneration of dopaminergic neurons in the substantia nigra pars compacta, which has been suggested to result from the accumulation of damaged mitochondria. However, ultrastructural changes of mitochondria specifically in dopaminergic neurons derived from iPSC have rarely been analyzed. The main reason for this would be that the dopaminergic neurons cannot be distinguished directly among a mixture of iPSC-derived differentiated cells under electron microscopy. To selectively label dopaminergic neurons and analyze mitochondrial morphology at the ultrastructural level, we generated control and PRKN-mutated patient tyrosine hydroxylase reporter (TH-GFP) induced pluripotent stem cell (iPSC) lines. Correlative light-electron microscopy analysis and live cell imaging of GFP-expressing dopaminergic neurons indicated that iPSC-derived dopaminergic neurons had smaller and less functional mitochondria than those in non-dopaminergic neurons. Furthermore, the formation of spheroid-shaped mitochondria, which was induced in control dopaminergic neurons by a mitochondrial uncoupler, was inhibited in the PRKN-mutated dopaminergic neurons. These results indicate that our established TH-GFP iPSC lines are useful for characterizing mitochondrial morphology, such as spheroid-shaped mitochondria, in dopaminergic neurons among a mixture of various cell types. Our in vitro model would provide insights into the vulnerability of dopaminergic neurons and the processes leading to the preferential loss of dopaminergic neurons in patients with PRKN mutations.

scholarly journals Altered Electrical, Biomolecular, and Immunologic Phenotypes in a Novel Patient-Derived Stem Cell Model of Desmoglein-2 Mutant ARVC

2021 ◽  
Vol 10 (14) ◽  
pp. 3061
Author(s):  
Robert N. Hawthorne ◽  
Adriana Blazeski ◽  
Justin Lowenthal ◽  
Suraj Kannan ◽  
Roald Teuben ◽  
...  
Keyword(s):  
Stem Cell ◽  
Structural Changes ◽  
Cell Model ◽  
Arrhythmogenic Right Ventricular Cardiomyopathy ◽  
Induced Pluripotent Stem Cell ◽  
Cytokine Expression ◽  
Calcium Handling ◽  
Disease Manifestation ◽  
Time To Peak ◽  
Induced Pluripotent

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive heart condition which causes fibro-fatty myocardial scarring, ventricular arrhythmias, and sudden cardiac death. Most cases of ARVC can be linked to pathogenic mutations in the cardiac desmosome, but the pathophysiology is not well understood, particularly in early phases when arrhythmias can develop prior to structural changes. Here, we created a novel human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of ARVC from a patient with a c.2358delA variant in desmoglein-2 (DSG2). These DSG2-mutant (DSG2Mut) hiPSC-CMs were compared against two wildtype hiPSC-CM lines via immunostaining, RT-qPCR, Western blot, RNA-Seq, cytokine expression and optical mapping. Mutant cells expressed reduced DSG2 mRNA and had altered localization of desmoglein-2 protein alongside thinner, more disorganized myofibrils. No major changes in other desmosomal proteins were noted. There was increased pro-inflammatory cytokine expression that may be linked to canonical and non-canonical NFκB signaling. Action potentials in DSG2Mut CMs were shorter with increased upstroke heterogeneity, while time-to-peak calcium and calcium decay rate were reduced. These were accompanied by changes in ion channel and calcium handling gene expression. Lastly, suppressing DSG2 in control lines via siRNA allowed partial recapitulation of electrical anomalies noted in DSG2Mut cells. In conclusion, the aberrant cytoskeletal organization, cytokine expression, and electrophysiology found DSG2Mut hiPSC-CMs could underlie early mechanisms of disease manifestation in ARVC patients.

Low-dose aspirin prevents age-related endothelial dysfunction in a mouse model of physiological aging

2008 ◽  
Vol 294 (4) ◽  
pp. H1562-H1570 ◽  
Author(s):  
Hélène Bulckaen ◽  
Gaétan Prévost ◽  
Eric Boulanger ◽  
Géraldine Robitaille ◽  
Valérie Roquet ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Dysfunction ◽  
Protective Effect ◽  
Structural Changes ◽  
Low Dose ◽  
Age Groups ◽  
Dose Aspirin ◽  
Age Related ◽  
Low Dose Aspirin ◽  
Old Mice

The age-related impairment of endothelium-dependent vasodilatation contributes to increased cardiovascular risk in the elderly. For primary and secondary prevention, aspirin can reduce the incidence of cardiovascular events in this patient population. The present work evaluated the effect of low-dose aspirin on age-related endothelial dysfunction in C57B/J6 aging mice and investigated its protective antioxidative effect. Age-related endothelial dysfunction was assessed by the response to acetylcholine of phenylephrine-induced precontracted aortic segments isolated from 12-, 36-, 60-, and 84-wk-old mice. The effect of low-dose aspirin was examined in mice presenting a decrease in endothelial-dependent relaxation (EDR). The effects of age and aspirin treatment on structural changes were determined in mouse aortic sections. The effect of aspirin on the oxidative stress markers malondialdehyde and 8-hydroxy-2′-deoxyguanosine (8-OhdG) was also quantified. Compared with that of 12-wk-old mice, the EDR was significantly reduced in 60- and 84-wk-old mice ( P < 0.05); 68-wk-old mice treated with aspirin displayed a higher EDR compared with control mice of the same age (83.9 ± 4 vs. 66.3 ± 5%; P < 0.05). Aspirin treatment decreased 8-OHdG levels ( P < 0.05), but no significant effect on intima/media thickness ratio was observed. The protective effect of aspirin was not observed when treatment was initiated in older mice (96 wk of age). It was found that low-dose aspirin is able to prevent age-related endothelial dysfunction in aging mice. However, the absence of this effect in the older age groups demonstrates that treatment should be initiated early on. The underlying mechanism may involve the protective effect of aspirin against oxidative stress.

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