Dataset Information

Structural and Mechanistic Bases of Nuclear Calcium Signaling in Human Pluripotent Stem Cell-Derived Ventricular Cardiomyocytes.

ABSTRACT: The loss of nonregenerative, terminally differentiated cardiomyocytes (CMs) due to aging or diseases is generally considered irreversible. Human pluripotent stem cells (hPSCs) can self-renew while maintaining their pluripotency to differentiate into all cell types, including ventricular (V) cardiomyocytes (CMs), to provide a potential unlimited ex vivo source of CMs for heart disease modeling, drug/cardiotoxicity screening, and cell-based therapies. In the human heart, cytosolic Ca2+ signals are well characterized but the contribution of nuclear Ca2+ is essentially unexplored. The present study investigated nuclear Ca2+ signaling in hPSC-VCMs. Calcium transient or sparks in hPSC-VCMs were measured by line scanning using a spinning disc confocal microscope. We observed that nuclear Ca2+, which stems from unitary sparks due to the diffusion of cytosolic Ca2+ that are mediated by RyRs on the nuclear reticulum, is functional. Parvalbumin- (PV-) mediated Ca2+ buffering successfully manipulated Ca2+ transient and stimuli-induced apoptosis in hPSC-VCMs. We also investigated the effect of Ca2+ on gene transcription in hPSC-VCMs, and the involvement of nuclear factor of activated T-cell (NFAT) pathway was identified. The overexpression of Ca2+-sensitive, nuclear localized Ca2+/calmodulin-dependent protein kinase II ? B (CaMKII? B) induced cardiac hypertrophy through nuclear Ca2+/CaMKII?B/HDAC4/MEF2 pathway. These findings provide insights into nuclear Ca2+ signal in hPSC-VCMs, which may lead to novel strategies for maturation as well as improved systems for disease modeling, drug discovery, and cell-based therapies.

SUBMITTER: Li S

PROVIDER: S-EPMC6466844 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Structural and Mechanistic Bases of Nuclear Calcium Signaling in Human Pluripotent Stem Cell-Derived Ventricular Cardiomyocytes.

Li Sen S Keung Wendy W Cheng Heping H Li Ronald A RA

Stem cells international 20190401

The loss of nonregenerative, terminally differentiated cardiomyocytes (CMs) due to aging or diseases is generally considered irreversible. Human pluripotent stem cells (hPSCs) can self-renew while maintaining their pluripotency to differentiate into all cell types, including ventricular (V) cardiomyocytes (CMs), to provide a potential unlimited <i>ex vivo</i> source of CMs for heart disease modeling, drug/cardiotoxicity screening, and cell-based therapies. In the human heart, cytosolic Ca<sup>2+ ...[more]

PMID: 31065282

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Project description:RationaleCardiomyocytes generated from human induced pluripotent stem cells (hiPSCs) are suggested as the most promising candidate to replenish cardiomyocyte loss in regenerative medicine. Little is known about their calcium homeostasis, the key process underlying excitation-contraction coupling.ObjectiveWe investigated the calcium handling properties of hiPSC-derived cardiomyocytes and compared with those from human embryonic stem cells (hESCs).Methods and resultsWe differentiated cardiomyocytes from hiPSCs (IMR90 and KS1) and hESCs (H7 and HES3) with established protocols. Beating outgrowths from embryoid bodies were typically observed 2 weeks after induction. Cells in these outgrowths were stained positively for tropomyosin and sarcomeric alpha-actinin. Reverse-transcription polymerase chain reaction studies demonstrated the expressions of cardiac-specific markers in both hiPSC- and hESC-derived cardiomyocytes. Calcium handling properties of 20-day-old hiPSC- and hESC-derived cardiomyocytes were investigated using fluorescence confocal microscopy. Compared with hESC-derived cardiomyocytes, spontaneous calcium transients from both lines of hiPSC-derived cardiomyocytes were of significantly smaller amplitude and with slower maximal upstroke velocity. Better caffeine-induced calcium handling kinetics in hESC-CMs indicates a higher sacroplasmic recticulum calcium store. Furthermore, in contrast with hESC-derived cardiomyocytes, ryanodine did not reduce the amplitudes, maximal upstroke and decay velocity of calcium transients of hiPSC-derived cardiomyocytes. In addition, spatial inhomogeneity in temporal properties of calcium transients across the width of cardiomyocytes was more pronounced in hiPSC-derived cardiomyocytes than their hESC counterpart as revealed line-scan calcium imaging. Expressions of the key calcium-handling proteins including ryanodine recptor-2 (RyR2), sacroplasmic recticulum calcium-ATPase (SERCA), junction (Jun) and triadin (TRDN), were significantly lower in hiPSC than in hESCs.ConclusionsThe results indicate the calcium handling properties of hiPSC-derived cardiomyocytes are relatively immature to hESC counterparts.

Project description:Despite preclinical studies demonstrating the functional benefit of transplanting human pluripotent stem cell-derived cardiomyocytes (PSC-CMs) into damaged myocardium, the ability of these immature cells to adopt a more adult-like cardiomyocyte (CM) phenotype remains uncertain. To address this issue, we tested the hypothesis that prolonged in vitro culture of human embryonic stem cell (hESC)- and human induced pluripotent stem cell (hiPSC)-derived CMs would result in the maturation of their structural and contractile properties to a more adult-like phenotype. Compared to their early-stage counterparts (PSC-CMs after 20-40 days of in vitro differentiation and culture), late-stage hESC-CMs and hiPSC-CMs (80-120 days) showed dramatic differences in morphology, including increased cell size and anisotropy, greater myofibril density and alignment, sarcomeres visible by bright-field microscopy, and a 10-fold increase in the fraction of multinucleated CMs. Ultrastructural analysis confirmed improvements in the myofibrillar density, alignment, and morphology. We measured the contractile performance of late-stage hESC-CMs and hiPSC-CMs and noted a doubling in shortening magnitude with slowed contraction kinetics compared to the early-stage cells. We then examined changes in the calcium-handling properties of these matured CMs and found an increase in calcium release and reuptake rates with no change in the maximum amplitude. Finally, we performed electrophysiological assessments in hESC-CMs and found that late-stage myocytes have hyperpolarized maximum diastolic potentials, increased action potential amplitudes, and faster upstroke velocities. To correlate these functional changes with gene expression, we performed qPCR and found a robust induction of the key cardiac structural markers, including ?-myosin heavy chain and connexin-43, in late-stage hESC-CMs and hiPSC-CMs. These findings suggest that PSC-CMs are capable of slowly maturing to more closely resemble the phenotype of adult CMs and may eventually possess the potential to regenerate the lost myocardium with robust de novo force-producing tissue.

Project description:BackgroundWhile mutations in the cardiac type 2 ryanodine receptor (RyR2) have been linked to exercise-induced or catecholaminergic polymorphic ventricular tachycardia (CPVT), its association with polymorphic ventricular tachycardia (PMVT) occurring at rest is unclear. We aimed at constructing a patient-specific human-induced pluripotent stem cell (hiPSC) model of PMVT occurring at rest linked to a single point mutation in RyR2.MethodsBlood samples were obtained from a patient with PMVT at rest due to a heterozygous RyR2-H29D mutation. Patient-specific hiPSCs were generated from the blood samples, and the hiPSC-derived cardiomyocytes (CMs) were generated via directed differentiation. Using CRIPSR/Cas9 technology, isogenic controls were generated by correcting the RyR2-H29D mutation. Using patch-clamp, fluorescent confocal microscopy and video-image-based analysis, the molecular and functional properties of RyR2-H29D hiPSCCMs and control hiPSCCMs were compared.FindingsRyR2-H29D hiPSCCMs exhibit intracellular sarcoplasmic reticulum (SR) Ca2+ leak through RyR2 under physiological pacing. RyR2-H29D enhances the contribution of inositol 1,4,5-trisphosphate receptors to excitation-contraction coupling (ECC) that exacerbates abnormal Ca2+ release in RyR2-H29D hiPSCCMs. RyR2-H29D hiPSCCMs exhibit shorter action potentials, delayed afterdepolarizations, arrhythmias and aberrant contractile properties compared to isogenic controls. The RyR2-H29D mutation causes post-translational remodeling that is fully reversed with isogenic controls.InterpretationTo conclude, in a model based on a RyR2 point mutation that is associated with short-coupled PMVT at rest, RyR2-H29D hiPSCCMs exhibited aberrant intracellular Ca2+ homeostasis, shortened action potentials, arrhythmias and abnormal contractile properties.FundingFrench Muscular Dystrophy Association (AFM; project 16,073, MNM2 2012 and 20,225), "Fondation de la Recherche Médicale" (FRM; SPF20130526710), "Institut National pour la Santé et la Recherche Médicale" (INSERM), National Institutes of Health (ARM; R01 HL145473) and New York State Department of Health (NYSTEM C029156).

Dataset Information

Structural and Mechanistic Bases of Nuclear Calcium Signaling in Human Pluripotent Stem Cell-Derived Ventricular Cardiomyocytes.

Publications

Structural and Mechanistic Bases of Nuclear Calcium Signaling in Human Pluripotent Stem Cell-Derived Ventricular Cardiomyocytes.

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