Mechanism of automaticity in cardiomyocytes derived from human induced pluripotent stem cells

Jong J Kim; Lei Yang; Bo Lin; Xiaodong Zhu; Bin Sun; Aaron D Kaplan; Glenna C.L Bett; Randall L Rasmusson; Barry London; Guy Salama

doi:10.1016/j.yjmcc.2015.01.013

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Mechanism of automaticity in cardiomyocytes derived from human induced pluripotent stem cells

Journal article

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Mechanism of automaticity in cardiomyocytes derived from human induced pluripotent stem cells

Jong J Kim, Lei Yang, Bo Lin, Xiaodong Zhu, Bin Sun, Aaron D Kaplan, Glenna C.L Bett, Randall L Rasmusson, Barry London and Guy Salama

Journal of molecular and cellular cardiology, Vol.81, pp.81-93

04/2015

DOI: 10.1016/j.yjmcc.2015.01.013

PMCID: PMC4409767

PMID: 25644533

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Abstract

Background and objectives. The creation of cardiomyocytes derived from human induced pluripotent stem cells (hiPS-CMs) has spawned broad excitement borne out of the prospects to diagnose and treat cardiovascular diseases based on personalized medicine. A common feature of hiPS-CMs is their spontaneous contractions but the mechanism(s) remain uncertain. Methods. Intrinsic activity was investigated by the voltage-clamp technique, optical mapping of action potentials (APs) and intracellular Ca2+ (Cai) transients (CaiT) at subcellular-resolution and pharmacological interventions. Results. The frequency of spontaneous CaiT (sCaiT) in monolayers of hiPS-CMs was not altered by ivabradine, an inhibitor of the pacemaker current, If despite high levels of HCN transcripts (1–4). HiPS-CMs had negligible If and IK1 (inwardly-rectifying K+-current) and a minimum diastolic potential of −59.1±3.3mV (n=18). APs upstrokes were preceded by a depolarizing-foot coincident with a rise of Cai. Subcellular Cai wavelets varied in amplitude, propagated and died-off; larger Cai-waves triggered cellular sCaTs and APs. SCaiTs increased in frequency with [Ca2+]out (0.05-to-1.8mM), isoproterenol (1μM) or caffeine (100μM) (n≥5, p<0.05). HiPS-CMs became quiescent with ryanodine receptor stabilizers (K201=2μM); tetracaine; Na–Ca exchange (NCX) inhibition (SEA0400=2μM); higher [K+]out (5→8mM), and thiol-reducing agents but could still be electrically stimulated to elicit CaiTs. Cell–cell coupling of hiPS-CM in monolayers was evident from connexin-43 expression and CaiT propagation. SCaiTs from an ensemble of dispersed hiPS-CMs were out-of-phase but became synchronous through the outgrowth of inter-connecting microtubules. Conclusions. Automaticity in hiPS-CMs originates from a Ca2+-clock mechanism involving Ca2+ cycling across the sarcoplasmic reticulum linked to NCX to trigger APs. •HiPS-CMs hold great promise for personalized medicine to treat cardiac diseases.•The mechanisms underlying their automaticity remain unknown.•Ventricular hiPS-CMs express HCN message but no significant funny current, If.•Subcellular Ca2+ & Vm maps show that aberrant Ca2+ release precedes depolarization.•Stochastic subcellular Ca2+ waves control automaticity.

Human myocytes from stem cells

Subcellular calcium waves

Funny current

Cell–cell coupling

Optical mapping of calcium and action potentials

Spontaneous activity

Details

Title: Subtitle: Mechanism of automaticity in cardiomyocytes derived from human induced pluripotent stem cells
Creators: Jong J Kim - Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
Lei Yang - Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
Bo Lin - Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
Xiaodong Zhu - University of Iowa, Carver College of Medicine, Division of Cardiovascular Medicine, Iowa City, IA 52242, USA
Bin Sun - Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
Aaron D Kaplan - Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
Glenna C.L Bett - Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
Randall L Rasmusson - Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
Barry London - University of Iowa, Carver College of Medicine, Division of Cardiovascular Medicine, Iowa City, IA 52242, USA
Guy Salama - Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
Resource Type: Journal article
Publication Details: Journal of molecular and cellular cardiology, Vol.81, pp.81-93
DOI: 10.1016/j.yjmcc.2015.01.013
PMID: 25644533
PMCID: PMC4409767
NLM abbreviation: J Mol Cell Cardiol
ISSN: 0022-2828
eISSN: 1095-8584
Publisher: Elsevier Ltd
Grant note: name: Three Rivers Affiliate of the American Heart Association (AHA) Pre-Doctoral Fellowship; name: AHA SDG, award: (#11SDG5580002; name: AHA GIA; DOI: 10.13039/501100000850, name: National Heart and Lung Institute; DOI: 10.13039/100000050, name: NHLBI, award: HL093631, HL062465, HL70722, HL093074; name: RLR; name: DP2, award: 1DP2HL127727-01; DOI: 10.13039/100000002, name: NIH, award: DP1OD003819
Language: English
Date published: 04/2015
Academic Unit: Molecular Physiology and Biophysics; Cardiovascular Medicine; Internal Medicine
Record Identifier: 9984025582602771

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