Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes

Jonathan Satin, Izhak Kehat, Oren Caspi, Irit Huber, Gil Arbel, Ilanit Itzhaki, J. Magyar, Elizabeth A. Schroder, Ido Perlman, Lior Gepstein

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Abstract

Human embryonic stem cell-derived cardiomyocytes (hES-CMs) are thought to recapitulate the embryonic development of heart cells. Given the exciting potential of hES-CMs as replacement tissue in diseased hearts, we investigated the pharmacological sensitivity and ionic current of mid-stage hES-CMs (20-35 days post plating). A high-resolution microelectrode array was used to assess conduction in multicellular preparations of hES-CMs in spontaneously contracting embryoid bodies (EBs). TTX (10 μM) dramatically slowed conduction velocity from 5.1 to 3.2 cm s-1 while 100 μM TTX caused complete cessation of spontaneous electrical activity in all EBs studied. In contrast, the Ca2+ channel blockers nifedipine or diltiazem (1 μM) had a negligible effect on conduction. These results suggested a prominent Na+ channel current, and therefore we patch-clamped isolated cells to record Na+ current and action potentials (APs). We found for isolated hES-CMs a prominent Na+ current (244 ± 42 pA pF-1 at 0 mV; n = 19), and a hyperpolarization-activated current (HCN), but no inward rectifier K+ current. In cell clusters, 3 μM TTX induced longer AP interpulse intervals and 10 μM TTX caused cessation of spontaneous APs. In contrast nifedipine (Ca2+ channel block) and 2 mM Cs+ (HCN complete block) induced shorter AP interpulse intervals. In single cells, APs stimulated by current pulses had a maximum upstroke velocity (dV/dtmax) of 118 ± 14 V s-1 in control conditions; in contrast, partial block of Na+ current significantly reduced stimulated dV/dtmax (38 ± 15 V s-1). RT-PCR revealed NaV1.5, CaV1.2, and HCN-2 expression but we could not detect Kir2.1. We conclude that hES-CMs at mid-range development express prominent Na+ current. The absence of background K+ current creates conditions for spontaneous activity that is sensitive to TTX in the same range of partial block of NaV1.5; thus, the NaV1.5 Na+ channel is important for initiating spontaneous excitability in hES-derived heart cells.

Original languageEnglish
Pages (from-to)479-496
Number of pages18
JournalJournal of Physiology
Volume559
Issue number2
DOIs
Publication statusPublished - Sep 1 2004

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Cardiac Myocytes
Action Potentials
Embryoid Bodies
Nifedipine
Diltiazem
Microelectrodes
Embryonic Development
Human Embryonic Stem Cells
Heart Diseases
Pharmacology
Polymerase Chain Reaction

ASJC Scopus subject areas

  • Physiology

Cite this

Satin, J., Kehat, I., Caspi, O., Huber, I., Arbel, G., Itzhaki, I., ... Gepstein, L. (2004). Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes. Journal of Physiology, 559(2), 479-496. https://doi.org/10.1113/jphysiol.2004.068213

Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes. / Satin, Jonathan; Kehat, Izhak; Caspi, Oren; Huber, Irit; Arbel, Gil; Itzhaki, Ilanit; Magyar, J.; Schroder, Elizabeth A.; Perlman, Ido; Gepstein, Lior.

In: Journal of Physiology, Vol. 559, No. 2, 01.09.2004, p. 479-496.

Research output: Contribution to journalArticle

Satin, J, Kehat, I, Caspi, O, Huber, I, Arbel, G, Itzhaki, I, Magyar, J, Schroder, EA, Perlman, I & Gepstein, L 2004, 'Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes', Journal of Physiology, vol. 559, no. 2, pp. 479-496. https://doi.org/10.1113/jphysiol.2004.068213
Satin, Jonathan ; Kehat, Izhak ; Caspi, Oren ; Huber, Irit ; Arbel, Gil ; Itzhaki, Ilanit ; Magyar, J. ; Schroder, Elizabeth A. ; Perlman, Ido ; Gepstein, Lior. / Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes. In: Journal of Physiology. 2004 ; Vol. 559, No. 2. pp. 479-496.
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AU - Itzhaki, Ilanit

AU - Magyar, J.

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