This research was supported by AHA Scientist Development Grant 17SDG33700093 (F.S.); Mount Sinai KL2 Scholars Award for Clinical and Translational Research Career Development KL2TR001435 (F.S.); NIH R00 HL116645 and AHA 18TPA34170460 (C.K.).

The experiments using adult rat cardiomyocytes in this study were conducted with approved Institutional Animal Care and Use Committee (IACUC) protocols of Icahn School of Medicine at Mount Sinai. The adult rat cardiomyocytes were isolated from Sprague Dawley rat hearts by the Langendorff-based method as previously described16.
1. Preparation of Media
<ol>
	<li>Prepare hiPSC media.
	<ol>
		<li>Equilibrate the supplement and the basal medium to room temperature (RT). En...

<ol>
	<li>Karakikes, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correction+of+human+phospholamban+R14del+mutation+associated+with+cardiomyopathy+using+targeted+nucleases+and+combination+therapy.">Correction of human phospholamban R14del mutation associated with cardiomyopathy using targeted nucleases and combination therapy.</a> Nature Communications. 6, 6955 (2015).</li><li>Moretti, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patient-specific+induced+pluripotent+stem-cell+models+for+long-QT+syndrome.">Patient-specific induced pluripotent stem-cell models for long-QT syndrome.</a> The New England Journal of Medicine. 363 (15), 1397-1409 (2010).</li><li>Davis, R. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiomyocytes+derived+from+pluripotent+stem+cells+recapitulate+electrophysiological+characteristics+of+an+overlap+syndrome+of+cardiac+sodium+channel+disease.">Cardiomyocytes derived from pluripotent stem cells recapitulate electrophysiological characteristics of an overlap syndrome of cardiac sodium channel disease.</a> Circulation. 125 (25), 3079-3091 (2012).</li><li>Fatima, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+modeling+of+ryanodine+receptor+2+dysfunction+using+human+induced+pluripotent+stem+cells.">In vitro modeling of ryanodine receptor 2 dysfunction using human induced pluripotent stem cells.</a> Cellular Physiology and Biochemistry: International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology. 28 (4), 579-592 (2011).</li><li>Novak, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiomyocytes+generated+from+CPVTD307H+patients+are+arrhythmogenic+in+response+to+beta-adrenergic+stimulation.">Cardiomyocytes generated from CPVTD307H patients are arrhythmogenic in response to beta-adrenergic stimulation.</a> Journal of Cellular and Molecular Medicine. 16 (3), 468-482 (2012).</li><li>Lan, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abnormal+calcium+handling+properties+underlie+familial+hypertrophic+cardiomyopathy+pathology+in+patient-specific+induced+pluripotent+stem+cells.">Abnormal calcium handling properties underlie familial hypertrophic cardiomyopathy pathology in patient-specific induced pluripotent stem cells.</a> Cell Stem Cell. 12 (1), 101-113 (2013).</li><li>Sun, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patient-specific+induced+pluripotent+stem+cells+as+a+model+for+familial+dilated+cardiomyopathy.">Patient-specific induced pluripotent stem cells as a model for familial dilated cardiomyopathy.</a> Science Translational Medicine. 4 (130), (2012).</li><li>Stillitano, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+susceptibility+to+drug-induced+long+QT+with+a+panel+of+subject-specific+induced+pluripotent+stem+cells.">Modeling susceptibility to drug-induced long QT with a panel of subject-specific induced pluripotent stem cells.</a> eLife. 6, (2017).</li><li>Matsa, E., Burridge, P. W., Wu, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+stem+cells+for+modeling+heart+disease+and+for+drug+discovery.">Human stem cells for modeling heart disease and for drug discovery.</a> Science Translational Medicine. 6 (239), (2014).</li><li>Mordwinkin, N. M., Lee, A. S., Wu, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patient-specific+stem+cells+and+cardiovascular+drug+discovery.">Patient-specific stem cells and cardiovascular drug discovery.</a> Journal of the American Medical Association. 310 (19), 2039-2040 (2013).</li><li>Youssef, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Promise+and+Challenge+of+Induced+Pluripotent+Stem+Cells+for+Cardiovascular+Applications.">The Promise and Challenge of Induced Pluripotent Stem Cells for Cardiovascular Applications.</a> Journal of the American College of Cardiology: Basic to Translational Science. 1 (6), 510-523 (2016).</li><li>Cyganek, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deep+phenotyping+of+human+induced+pluripotent+stem+cell-derived+atrial+and+ventricular+cardiomyocytes.">Deep phenotyping of human induced pluripotent stem cell-derived atrial and ventricular cardiomyocytes.</a> Journal of Clinical Investigation: Insight. 3, 12 (2018).</li><li>Keung, W., Boheler, K. R., Li, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+cues+for+the+maturation+of+metabolic,+electrophysiological+and+calcium+handling+properties+of+human+pluripotent+stem+cell-derived+cardiomyocytes.">Developmental cues for the maturation of metabolic, electrophysiological and calcium handling properties of human pluripotent stem cell-derived cardiomyocytes.</a> Stem Cell Research, Therapy. 5 (1), 17 (2014).</li><li>Bhattacharya, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+efficiency+differentiation+of+human+pluripotent+stem+cells+to+cardiomyocytes+and+characterization+by+flow+cytometry.">High efficiency differentiation of human pluripotent stem cells to cardiomyocytes and characterization by flow cytometry.</a> Journal of Visualized Experiments: JoVE. (91), e52010 (2014).</li><li>Ronaldson-Bouchard, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advanced+maturation+of+human+cardiac+tissue+grown+from+pluripotent+stem+cells.">Advanced maturation of human cardiac tissue grown from pluripotent stem cells.</a> Nature. 556 (7700), 239-243 (2018).</li><li>Gorski, P. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+Cardiomyocyte+Contractility+and+Calcium+Handling+In+Vitro.">Measuring Cardiomyocyte Contractility and Calcium Handling In Vitro.</a> Methods in Molecular Biology. 1816, 93-104 (2018).</li><li>Kim, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-cardiomyocytes+influence+the+electrophysiological+maturation+of+human+embryonic+stem+cell-derived+cardiomyocytes+during+differentiation.">Non-cardiomyocytes influence the electrophysiological maturation of human embryonic stem cell-derived cardiomyocytes during differentiation.</a> Stem Cells and Development. 19 (6), 783-795 (2010).</li><li>Lian, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Directed+cardiomyocyte+differentiation+from+human+pluripotent+stem+cells+by+modulating+Wnt/beta-catenin+signaling+under+fully+defined+conditions.">Directed cardiomyocyte differentiation from human pluripotent stem cells by modulating Wnt/beta-catenin signaling under fully defined conditions.</a> Nature Protocols. 8 (1), 162-175 (2013).</li><li>Patterson, A. J., Zhang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia+and+fetal+heart+development.">Hypoxia and fetal heart development.</a> Current Molecular Medicine. 10 (7), 653-666 (2010).</li><li>Correia, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+hypoxia+and+bioreactor+hydrodynamics+boosts+induced+pluripotent+stem+cell+differentiation+towards+cardiomyocytes.">Combining hypoxia and bioreactor hydrodynamics boosts induced pluripotent stem cell differentiation towards cardiomyocytes.</a> Stem Cell Reviews. 10 (6), 786-801 (2014).</li><li>Tohyama, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glutamine+Oxidation+Is+Indispensable+for+Survival+of+Human+Pluripotent+Stem+Cells.">Glutamine Oxidation Is Indispensable for Survival of Human Pluripotent Stem Cells.</a> Cell Metabolism. 23 (4), 663-674 (2016).</li><li>Tohyama, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+metabolic+flow+enables+large-scale+purification+of+mouse+and+human+pluripotent+stem+cell-derived+cardiomyocytes.">Distinct metabolic flow enables large-scale purification of mouse and human pluripotent stem cell-derived cardiomyocytes.</a> Cell Stem Cell. 12 (1), 127-137 (2013).</li><li>Tu, C., Chao, B. S., Wu, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+for+Improving+the+Maturity+of+Human+Induced+Pluripotent+Stem+Cell-Derived+Cardiomyocytes.">Strategies for Improving the Maturity of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.</a> Circulation Research. 123 (5), 512-514 (2018).</li><li>Lundy, S. D., Zhu, W. Z., Regnier, M., Laflamme, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+functional+maturation+of+cardiomyocytes+derived+from+human+pluripotent+stem+cells.">Structural and functional maturation of cardiomyocytes derived from human pluripotent stem cells.</a> Stem Cells and Development. 22 (14), 1991-2002 (2013).</li><li>Hwang, H. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparable+calcium+handling+of+human+iPSC-derived+cardiomyocytes+generated+by+multiple+laboratories.">Comparable calcium handling of human iPSC-derived cardiomyocytes generated by multiple laboratories.</a> Journal of Molecular and Cellular Cardiology. 85, 79-88 (2015).</li><li>Scuderi, G. J., Butcher, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Naturally+Engineered+Maturation+of+Cardiomyocytes.">Naturally Engineered Maturation of Cardiomyocytes.</a> Frontiers in Cell and Developmental Biology. 5, 50 (2017).</li><li>Jung, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-dependent+evolution+of+functional+vs.+remodeling+signaling+in+induced+pluripotent+stem+cell-derived+cardiomyocytes+and+induced+maturation+with+biomechanical+stimulation.">Time-dependent evolution of functional vs. remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation.</a> FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology. 30 (4), 1464-1479 (2016).</li></ol>

Critical steps for using human iPSC-CMs as experimental models are: 1) generating high-quality cardiomyocytes (CMs) that can ensure the consistent performance and reproducible results; 2) allowing the cells to mature in culture for at least 90 days to adequately assess their phenotype; 3) performing electrophysiological studies, e.g. calcium (Ca2+) transient measurements, to provide a physiologically relevant functional characterization of human iPSC-CMs. We developed a monolayer-based differentiation method t...

Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) are an attractive human-based platform to model a large variety of cardiac diseases in vitro1,2,3,4,5,6,7,8. Moreover, iPSC-CMs can be used for the prediction of patient responses to novel or existing drugs, to screen hit compounds, and develop new personalized drugs9,10. However, despite significant progress, several limitations and challenges need to be considered when using iPSC-CMs11. Consequently, methods to improve cardiac differentiation protocols, to enhance iPSC-CMs efficiency and maturation, and to generate specific cardiomyocyte subtypes (ventricular, atrial, and nodal) have been intensely studied and already led to numerous culture strategies to overcome these hurdles12,13,14,15.
Notwithstanding the robustness of these protocols, a major concern for the use of iPSC-CMs is the reproducibility of long and complex procedures to obtain high-quality cardiomyocytes that can ensure the same performance and reproducible results. Reproducibility is critical not only when comparing cell lines with different genetic backgrounds, but also when repeating cellular and molecular comparisons of the same cell line. Cell variability, such as well-to-well differences in iPSCs density, may affect cardiac differentiation, generating a low yield and poor-quality cardiomyocytes. These cells could still be used to perform experiments that do not require a pure population of CMs (e.g., when performing Ca2+ transient measurements). Indeed, when performing electrophysiological analysis, the non-CMs will not beat, neither spontaneously nor under electrical stimulation, so it will be easy to exclude them from the analysis. However, because of the poor quality, iPSC-CMs can show altered electrophysiological characteristics (e.g., irregular Ca2+ transient, low Ca2+ amplitude) which are not due to their genetic makeup. Therefore, especially when using iPSC-CMs to model cardiac disease, it is important not to confuse results from a poor-quality CM with the disease phenotype. Careful screening and exclusion processes are required prior to proceeding to electrophysiological studies.
This method includes optimized protocols to generate high-purity and high-quality cardiomyocytes and to assess their function by performing Ca2+ transient measurements using a calcium and contractility acquisition and analysis system. This technique is a simple, yet powerful, way to distinguish between high efficiency and low efficiency iPSC-CM preparations and provide a more physiologically relevant characterization of human iPSC-CMs.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Anti-Actin, &#945;-Smooth Muscle antibody, Mouse monoclonal</td>
			<td>Sigma Aldrich</td>
			<td>A5228</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 488 goat anti mouse</td>
			<td>Invitrogen</td>
			<td>A11001</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 555 goat anti rabbit</td>
			<td>Invitrogen</td>
			<td>A21428</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 Supplement</td>
			<td>Gibco</td>
			<td>17504-044</td>
			<td></td>
		</tr>
		<tr>
			<td>B27(-) insulin Supplement</td>
			<td>Gibco</td>
			<td>A18956-01</td>
			<td></td>
		</tr>
		<tr>
			<td>CHIR-99021</td>
			<td>Selleckchem</td>
			<td>S2924</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI nuclear stain</td>
			<td>ThermoFisher</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12 (1:1) (1X) + L- Glutamine + 15mM Hepes</td>
			<td>Gibco</td>
			<td>11330-032</td>
			<td></td>
		</tr>
		<tr>
			<td>Double Ended Cell lifter, Flat blade and J-Hook</td>
			<td>Celltreat</td>
			<td>229306</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Multiwell Tissue Culture Plate, 6 well</td>
			<td>Corning</td>
			<td>353046</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluidic inline heater</td>
			<td>Live Cell Instrument</td>
			<td>IL-H-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Fura-2, AM</td>
			<td>Invitrogen</td>
			<td>F1221</td>
			<td></td>
		</tr>
		<tr>
			<td>hESC-qualified matrix</td>
			<td>Corning</td>
			<td>354277</td>
			<td>Matrigel Matrix</td>
		</tr>
		<tr>
			<td>hPSC media</td>
			<td>Gibco</td>
			<td>A33493-01</td>
			<td>StemFlex Basal Medium</td>
		</tr>
		<tr>
			<td>IWR-1</td>
			<td>Sigma Aldrich</td>
			<td>I0161</td>
			<td></td>
		</tr>
		<tr>
			<td>Live cell imaging chamber</td>
			<td>Live Cell Instrument</td>
			<td>EC-B25</td>
			<td></td>
		</tr>
		<tr>
			<td>MLC-2A, Monoclonal Mouse Antibody</td>
			<td>Synaptic Systems</td>
			<td>311011</td>
			<td></td>
		</tr>
		<tr>
			<td>Myocyte calcium and contractility system</td>
			<td>Ionoptix</td>
			<td>ISW-400</td>
			<td></td>
		</tr>
		<tr>
			<td>Myosin Light Chain 2 Antibody, Rabbit Polyclonal (MLC2V)</td>
			<td>Proteintech</td>
			<td>10906-1-AP</td>
			<td></td>
		</tr>
		<tr>
			<td>Nalgene Rapid Flow Sterile Disposable Filter units with PES Membrane</td>
			<td>ThermoFisher</td>
			<td>124-0045</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS with Calcium and Magnesium</td>
			<td>Corning</td>
			<td>21-030-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS without Calcium and Magensium</td>
			<td>Corning</td>
			<td>21-031-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Premium Glass Cover Slips</td>
			<td>Lab Scientific</td>
			<td>7807</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI medium 1640 (-) D-glucose (1X)</td>
			<td>Gibco</td>
			<td>11879-020</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI medium 1640 (1X)</td>
			<td>Gibco</td>
			<td>11875-093</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium L-lactate</td>
			<td>Sigma Aldrich</td>
			<td>L7022</td>
			<td></td>
		</tr>
		<tr>
			<td>StemFlex Supplement</td>
			<td>Gibco</td>
			<td>A33492-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Thiazovivin</td>
			<td>Tocris</td>
			<td>3845</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%)</td>
			<td>ThermoFisher</td>
			<td>25200056</td>
			<td></td>
		</tr>
		<tr>
			<td>Tyrode&#39;s solution</td>
			<td>Boston Bioproducts</td>
			<td>BSS-355w</td>
			<td>Adjust pH at 7.2. Add 1.2mM Calcium Chloride</td>
		</tr>
	</tbody>
</table>

generation of ventricular-like hipsc-derived cardiomyocytes and high-quality cell preparations for calcium handling characterization

Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) provide a valuable human source for studying the basic science of calcium (Ca2+) handling and signaling pathways as well as high-throughput drug screening and toxicity assays. Herein, we provide a detailed description of the methodologies used to generate high-quality iPSC-CMs that can consistently reproduce molecular and functional characteristics across different cell lines. Additionally, a method is described to reliably assess their functional characterization through the evaluation of Ca2+ handling properties. Low oxygen (O2) conditions, lactate selection, and prolonged time in culture produce high-purity and high-quality ventricular-like cardiomyocytes. Similar to isolated adult rat cardiomyocytes (ARCMs), 3-month-old iPSC-CMs exhibit higher Ca2+ amplitude, faster rate of Ca2+ reuptake (decay-tau), and a positive lusitropic response to &#946;-adrenergic stimulation compared to day 30 iPSC-CMs. The strategy is technically simple, cost-effective, and reproducible. It provides a robust platform to model cardiac disease and for the large-scale drug screening to target Ca2+ handling proteins.

The protocol described in Figure 1A generated highly pure cardiomyocytes that acquire a ventricular/adult-like phenotype with time in culture. As assessed by immunofluorescence staining for the atrial and ventricular myosin regulatory light chain 2 isoforms (MLC2A and MLC2V, respectively), the majority of the cells generated by this protocol were MLC2A-positive at day 30 after induction of cardiac differentiation, while MLC2V was expressed in much lower amounts at the same t...

Watch this Scientific Journal Video about Generation of Ventricular-Like HiPSC-Derived Cardiomyocytes and High-Quality Cell Preparations for Calcium Handling Characterization at JoVE.com

Generation of Ventricular-Like HiPSC-Derived Cardiomyocytes and High-Quality Cell Preparations for Calcium Handling Characterization

Here we describe and validate a method to consistently generate robust human induced pluripotent stem cell-derived cardiomyocytes and characterize their function. These techniques may help in developing mechanistic insight into signaling pathways, provide a platform for large-scale drug screening, and reliably model cardiac diseases.

Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) provide a valuable human source for studying the basic science of calcium (Ca2+) ...

Reproducibility is major concern when inducing stem cell-derived cardiomyocytes. Using these methods, high purity and high quality cardiomyocytes can be generated from iPS for their use in functional studies. The main advantage of this technique is that is a simple, reliable, cost-effective, and extremely powerful method for obtaining purified, high quality preparations of iPSC-derived cardiomyocytes.For cell passaging, rinse the cells with one milliliter of PBS without calcium and magnesium for seven to 10 minutes before replacing the PBS with one milliliter of passaging medium. Using a cell lifter, gently scrape the cells from the bottom of the wells, and use sterile two milliliter glass pipette to mechanically dissociate the detached cells. When the cells have lifted into small clusters as visible under the microscope add passaging medium to split the cells at a one to six ratio.Next, aspirate the human embryonic stem cell qualified matrix from the six well plate. Then add one milliliter of passaging medium and one milliliter of dissociated cells to each well, and let the cells grow until they reach 70 to 80%confluency before starting a cardiac differentiation. At least 30 minutes before dissociating the iPSC-CMs, wipe individual glass cover slips with 70%ethanol, and place the cover slips into individual wells of a sterile six well plate.When the cover slips have dried, add a 250 to 300 microliters of human embryonic stem cell qualified matrix solution directly onto the center of each cover slip, and place the six well plate in the tissue culture hood. To dissociate the metabolically selected iPSC-CM add one milliliter of sterile 0.25%trypsin with EDTA to each well for a five minute incubation at 35 degrees celsius, and use a 1000 microliter pipette to mechanically dissociate the cells until a single cell suspension has been achieved. Pull the cells in sterile 15 milliliter conical tube, and wash each well with two milliliters of RPMI 20 medium per well.Then add the washes to the tube and pellet the cells by centrifugation. Resuspend the cells in a sufficient volume of medium to achieve a three times 10 to the fifth cells per 250 microliters of cells concentration. Use a 1000 milliliter pipette tip to dissociate the cells until the solution appears to be homogenous.Then aspirate 250 microliters of cells into a 1000 microliter pipette tip, and slowly dispense the entire volume of solution onto one human embryonic stem cell qualified matrix coded cover slip. When all of the cells have been seeded, carefully place the plate into the cell culture incubator overnight. Gently adding two milliliters of D7 medium to each well the next morning.When the selected iPSC-CMs reach at least three months old treat the cells with two microliters of Fura-2 AM for 10 minutes at 37 degrees Celsius, and power on the calcium analysis system. Initiate the ArcLamp and connect the tubes from the pump to the appropriate inlet and outlets and the electronic wire from the stimulator to the chamber. Place the chamber onto the system.Fill the ProFusion tube that runs through the fluidic inlined heater with 37 degrees Celsius warmed Tyrode's solution, and adjust the camera and framing aperture dimensions to minimize the background area. Fasten the glass cover slip seeded with iPSC-CMs into the chamber, and gently add 500 microliters of Tyrode's solution directly on top of the cover slip. Begin profusing the chamber with Tyrode's solution at a 1.5 milliliter per minute rate, and use an electric stimulator to pace the iPC-CMs with 1 Hertz field stimulation at 10 volts every four milliseconds for three to five minutes.When all of the dye has been washed out of the chamber adjust the viewing window to the upper left region of the cover slip, and begin the recording. After collecting a consistent stream of five to 10 peaks click pause to temporarily stop the recording and move the microscope stage to an adjacent area for the opposite end of the cover slip before resuming the recording. After scanning the calcium transience across the entire cover slip in the same manner over a period of 10 minutes analyze the data with an appropriate florescence trace analysis software according to the manufacturer's instructions.This protocol generates highly pure cardiomyocytes that acquire a ventricular, adult-like phenotype in culture over time. As assessed by immuno fluorescent staining for the atrial and ventricular MLC2 isoforms, the majority of cells generated by this protocol are atrial MLC2 isoform positive at day 30 after the induction of cardiac differentiation. While ventricular MLC2 isoforms are expressed in much numbers at the same time point.As the time in culture increases, a complete switch to the MLC2 isoforms is observed. These data were also confirmed by flow cytometric quantification of the percentage of atrial and ventricular MLC2 marker expressing cells. The calcium amplitude is significantly increased in the iPSC-CMs at day 90, similar to that observed for adult rat CMs.It's important to note that contaminating non-cardiac cells may influence the functional maturation of the human iPSC-CMs during differentiation. Further, when record calcium transients in iPSC-CMs it's necessary to allow the cells to stabilize at 37 degrees Celsius under constant stimulation for at least 200 seconds, and to restrict the recordings to a specific time window to ensure reproducible results. Remember to confirm that the iPSCs exhibit a homogeneous morphology and to allow the cells to grow to 70 to 80%confluency before initiating a cardiac differentiation.Pure quality in immature iPS-derived cardiomyocytes might show altered functional characteristics, which do not reflect the real phenotype, but could be misinterpreted as the diseased phenotype. Therefore, obtaining pure and high quality cardiomyocytes is important to provide consistent and reproducible results.

generation-ventricular-like-hipsc-derived-cardiomyocytes-high-quality

Research

JoVE Journal

Medicine

7.7K visualizações.  Icahn School of Medicine at Mount Sinai. A reprodutibilidade é uma grande preocupação ao induzir cardiomiócitos derivados de células-tronco. Utilizando esses métodos, cardiomiócitos de alta pureza e alta qualidade podem ser gerados a partir de iPS para seu uso em estudos funcionais. A principal vantagem desta técnica é que é um método simples, confiável, econômico e extremamente poderoso para obter preparações purificadas e de alta qualidade de cardiomiócitos derivados do iPSC.Para a passagem celular, enxágue...