Comparison of contractile behavior of native murine ventricular tissue and cardiomyocytes derived from embryonic or induced pluripotent stem cells

Institute for Neurophysiology, University of Cologne, Cologne, Germany.
The FASEB Journal (Impact Factor: 5.04). 04/2010; 24(8):2739-51. DOI: 10.1096/fj.09-145177
Source: PubMed


Cardiomyocytes generated from embryonic stem cells (ESCs) and induced pluripotent stem (iPS) cells are suggested for repopulation of destroyed myocardium. Because contractile properties are crucial for functional regeneration, we compared cardiomyocytes differentiated from ES cells (ESC-CMs) and iPS cells (iPS-CMs). Native myocardium served as control. Murine ESCs or iPS cells were differentiated 11 d in vitro and cocultured 5-7 d with irreversibly injured myocardial tissue slices. Vital embryonic ventricular tissue slices of similar age served for comparison. Force-frequency relationship (FFR), effects of Ca(2+), Ni(2+), nifedipine, ryanodine, beta-adrenergic, and muscarinic modulation were studied during loaded contractions. FFR was negative for ESC-CMs and iPS-CMs. FFR was positive for embryonic tissue and turned negative after treatment with ryanodine. In all groups, force of contraction and relaxation time increased with the concentration of Ca(2+) and decreased with nifedipine. Force was reduced by Ni(2+). Isoproterenol (1 microM) increased the force most pronounced in embryonic tissue (207+/-31%, n=7; ESC-CMs: 123+/-5%, n=4; iPS-CMs: 120+/-4%, n=8). EC(50) values were similar. Contractile properties of iPS-CMs and ESC-CMs were similar, but they were significantly different from ventricular tissue of comparable age. The results indicate immaturity of the sarcoplasmic reticulum and the beta-adrenergic response of iPS-CMs and ESC-CMs.

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    • "In LQT3 iPS-CM, we observed similar results to controls, where nifedipine caused AP shortening and arrested beating (Figure S4C). The more sustained automaticity in nifedipine-treated LQT2 iPS-CM may reflect a specific genetic process in that individual, or perhaps compensatory automaticity unmasked by the I Kr insufficiency (Itzhaki et al., 2011; Xi et al., 2010). When a cardiac AP is triggered, I Ca evokes a [Ca 2+ ] i "
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    ABSTRACT: Long-QT syndrome mutations can cause syncope and sudden death by prolonging the cardiac action potential (AP). Ion channels affected by mutations are various, and the influences of cellular calcium cycling on LQTS cardiac events are unknown. To better understand LQTS arrhythmias, we performed current-clamp and intracellular calcium ([Ca2+]i) measurements on cardiomyocytes differentiated from patient-derived induced pluripotent stem cells (iPS-CM). In myocytes carrying an LQT2 mutation (HERG-A422T), APs and [Ca2+]i transients were prolonged in parallel. APs were abbreviated by nifedipine exposure and further lengthened upon releasing intracellularly stored Ca2+. Validating this model, control iPS-CM treated with HERG-blocking drugs recapitulated the LQT2 phenotype. In LQT3 iPS-CM, expressing NaV1.5-N406K, APs and [Ca2+]i transients were markedly prolonged. AP prolongation was sensitive to tetrodotoxin and to inhibiting Na+-Ca2+ exchange. These results suggest that LQTS mutations act partly on cytosolic Ca2+ cycling, potentially providing a basis for functionally targeted interventions regardless of the specific mutation site.
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    • "Traditional video-based CM analysis methods [10,11] may not, however, be optimal for the study of single iPS cell-derived CMs. The sarcomere structure of iPS cell-derived CMs is not fully organized [12] and, therefore, their beating is less uniform with no main contraction direction. Thus, better methods are required that are robust in the detection of movement signals from these types of cells. "
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    • "Others are computationally complex or require mathematical estimations in order to determine twitch forces [17] [18] [19] [20]. The contractile properties of a population of cardiomyocytes have also been approximated by seeding these cells within a three-dimensional construct [33] [34] [35] [36] [37] [38] [39]. However, in this configuration , it is difficult to determine the actual contractile force produced by individual cells, since a portion of this contraction is lost to the rigidity of the bulk tissue and/or through its cell-cell contacts. "
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