Name: technical applications of microelectrode array and patch clamp recordings on human induced pluripotent stem cell-derived cardiomyocytes
Uploaded: 2022-08-04T14:45:00
Description: Watch this Scientific Journal Video about Technical Applications of Microelectrode Array and Patch Clamp Recordings on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes at JoVE.com

We thank Blake Wu for proofreading the manuscript. This work was supported by the National Institutes of Health (NIH) R01 HL113006, R01 HL141371, R01 HL163680, R01 HL141851, U01FD005978, and NASA NNX16A069A (JCW), and AHA Postdoctoral Fellowship 872244 (GMP).

1. Preparation of media and solutions
<ol>
	<li>Prepare hiPSC-CM maintenance medium by mixing a 10 mL bottle of 50x B27 supplement and 500 mL of RPMI 1640 medium. Store the medium at 4 &#176;C and use it within a month. Equilibrate the medium to room temperature (RT) before use.</li>
	<li>Prepare hiPSC-CM seeding medium by mixing 20 mL of serum replacement and 180 mL of hiPSC-CM maintenance medium (10% dilution, v/v). While freshly prepared seeding medium is preferred, it can be stored at 4 &#176;C for...

<ol>
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Z., 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=Protocol+to+measure+contraction,+calcium,+and+action+potential+in+human-induced+pluripotent+stem+cell-derived+cardiomyocytes.">Protocol to measure contraction, calcium, and action potential in human-induced pluripotent stem cell-derived cardiomyocytes.</a> STAR Protocols. 2 (4), 100859 (2021).</li><li>Blinova, 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=International+multisite+study+of+human-induced+pluripotent+stem+cell-derived+cardiomyocytes+for+drug+proarrhythmic+potential+assessment.">International multisite study of human-induced pluripotent stem cell-derived cardiomyocytes for drug proarrhythmic potential assessment.</a> Cell Reports. 24 (13), 3582-3592 (2018).</li><li>Greensmith, D. 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Z., 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=Effects+of+cryopreservation+on+human+induced+pluripotent+stem+cell-derived+cardiomyocytes+for+assessing+drug+safety+response+profiles.">Effects of cryopreservation on human induced pluripotent stem cell-derived cardiomyocytes for assessing drug safety response profiles.</a> Stem Cell Reports. 16 (1), 168-181 (2021).</li><li>Yu, B., Zhao, S. R., Yan, C. D., Zhang, M., 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=Deconvoluting+the+cells+of+the+human+heart+with+iPSC+technology:+cell+types,+protocols,+and+uses.">Deconvoluting the cells of the human heart with iPSC technology: cell types, protocols, and uses.</a> Current Cardiology Reports. 24 (5), 487-496 (2022).</li><li>Thomas, D., Cunningham, N. J., Shenoy, S., Wu, J. 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M., 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=Metabolic+maturation+media+improve+physiological+function+of+human+iPSC-derived+cardiomyocytes.">Metabolic maturation media improve physiological function of human iPSC-derived cardiomyocytes.</a> Cell Reports. 32 (3), 107925 (2020).</li><li>Gintant, 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=Use+of+human+induced+pluripotent+stem+cell-derived+cardiomyocytes+in+preclinical+cancer+drug+cardiotoxicity+testing:+a+scientific+statement+from+the+American+Heart+Association.">Use of human induced pluripotent stem cell-derived cardiomyocytes in preclinical cancer drug cardiotoxicity testing: a scientific statement from the American Heart Association.</a> Circulation Research. 125 (10), 75-92 (2019).</li><li>Kussauer, S., David, R., Lemcke, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=hiPSCs+Derived+cardiac+cells+for+drug+and+toxicity+screening+and+disease+modeling:+what+micro-+electrode-array+analyses+can+tell+us.">hiPSCs Derived cardiac cells for drug and toxicity screening and disease modeling: what micro- electrode-array analyses can tell us.</a> Cells. 8 (11), (2019).</li><li>Ng, C. 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Human iPSC technology has emerged as a powerful platform for disease modeling and drug screening. Here, we describe a detailed protocol for measuring hiPSC-CM contractility, field potential, action potential, and Ca2+ transient. This protocol provides a comprehensive characterization of hiPSC-CM contractility and electrophysiology. These functional assays have been applied in multiple publications from our group12,13,18</su...

Drug development is a long and expensive process. A study of new therapeutic drugs approved by the US Food and Drug Administration (FDA) between 2009 and 2018 reported that the estimated median cost of capitalized research and clinical trials was $985 million per product1. Drug-induced cardiotoxicity is the leading cause of drug attrition and withdrawal from the market2. Notably, cardiotoxicity is reported among multiple classes of therapeutic drugs3. Therefore, cardiac safety assessment is a crucial component during the drug development process. The current paradigm for cardiac safety assessment is still highly dependent on animal models. However, species differences from the use of animal models are increasingly recognized as a primary cause of inaccurate predictions for drug-induced cardiotoxicity in human patients4. For example, the morphology of cardiac action potential differs substantially between humans and mice due to the contributions from different repolarizing currents5. In addition, differential isoforms of cardiac myosin and circular RNAs that can impact cardiac physiology have been well documented among species6,7. To bridge these gaps, it is imperative to establish a reliable, efficient, and human-based model for preclinical cardiac safety assessment.
The groundbreaking invention of induced pluripotent stem cell (iPSC) technology has generated unprecedented drug screening and disease modeling platforms. Over the past decade, methods to generate human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have become well established8,9. hiPSC-CMs have attracted great interest in their potential applications in disease modeling, drug-induced cardiotoxicity screening, and precision medicine. For instance, hiPSC-CMs have been utilized to model the pathologic phenotypes of cardiac diseases caused by genetic inheritance, such as long QT syndrome10, hypertrophic cardiomyopathy11,12, and dilated cardiomyopathy13,14,15. Consequently, key signaling pathways implicated in the pathogenesis of cardiac diseases have been identified, which can shed light on potential therapeutic strategies for effective treatment. Moreover, hiPSC-CMs have been used to screen drug-induced cardiotoxicity associated with anticancer agents, including doxorubicin, trastuzumab, and tyrosine kinase inhibitors16,17,18; strategies to mitigate the resultant cardiotoxicity are under investigation. Finally, the genetic information retained in hiPSC-CMs allows for the screening and prediction of drug-induced cardiotoxicity at both individual and population levels19,20. Collectively, hiPSC-CMs have proven to be an invaluable tool for personalized cardiac safety prediction.
The overall goal of this protocol is to establish methodologies to comprehensively and efficiently investigate the functional characteristics of hiPSC-CMs, which are of great importance in applying hiPSC-CMs toward disease modeling, drug-induced cardiotoxicity screening, and precision medicine. Here, we detail an array of functional assays to assess the functional properties of hiPSC-CMs, including the measurement of contractility, field potential, action potential, and calcium (Ca2+) handling (Figure 1).

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>35 mm glass bottom dish with 20 mm micro-well #1.5 cover glass</td>
			<td>Cellvis</td>
			<td>D35-20-1.5-N</td>
			<td>Patch clamp</td>
		</tr>
		<tr>
			<td>50x B27 supplements</td>
			<td>Life Technologies</td>
			<td>17504-044</td>
			<td>hiPSC-CM culture medium</td>
		</tr>
		<tr>
			<td>6-well culture plate</td>
			<td>E &#38; K Scientific</td>
			<td>EK-27160</td>
			<td>hiPSC-CM culture</td>
		</tr>
		<tr>
			<td>96-well flat clear bottom black polystyrene TC-treated microplates</td>
			<td>Corning</td>
			<td>3603</td>
			<td>Contraction motion measurement</td>
		</tr>
		<tr>
			<td>Accutase</td>
			<td>Sigma-Aldrich</td>
			<td>A6964</td>
			<td>Enzymatic dissociation</td>
		</tr>
		<tr>
			<td>Axion&#39;s Integrated Studio (AxIS)</td>
			<td>Axion Biosystems</td>
			<td></td>
			<td>navigator software</td>
		</tr>
		<tr>
			<td>Borosilicate glass capillaries</td>
			<td>Harvard Apparatus</td>
			<td>BF 100-50-10,</td>
			<td>Patch clamp</td>
		</tr>
		<tr>
			<td>CaCl2 1 M in H2O</td>
			<td>Sigma-Aldrich</td>
			<td>21115</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>Cell counting chamber slides</td>
			<td>ThermoFisher Scientific</td>
			<td>C10228</td>
			<td>Cell counting</td>
		</tr>
		<tr>
			<td>CytoView 48-well MEA plates</td>
			<td>Axion Biosystems</td>
			<td>M768-tMEA-48B</td>
			<td>MEA</td>
		</tr>
		<tr>
			<td>DMEM/F12</td>
			<td>Gibco/Life Technologies</td>
			<td>12634028</td>
			<td>Extracellular matrix medium</td>
		</tr>
		<tr>
			<td>DPBS, no calcium, no magnesium</td>
			<td>Fisher Scientific</td>
			<td>14-190-250</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma-Aldrich</td>
			<td>E3889</td>
			<td>Intracellular pipette solution</td>
		</tr>
		<tr>
			<td>EPC 10 USB&#160;patch clamp amplifier</td>
			<td>Warner Instruments</td>
			<td>89-5000</td>
			<td>Patch clamp</td>
		</tr>
		<tr>
			<td>Fura-2, AM, cell permeant</td>
			<td>ThermoFisher Scientific</td>
			<td>F1221</td>
			<td>Ca2+ transient measurement</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G8270</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma-Aldrich</td>
			<td>H3375</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>hiPSCs</td>
			<td>Stanford Cardiovascular Institute iPSC Biobank</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma-Aldrich</td>
			<td>529552</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>KnockOut Serum Replacement</td>
			<td>ThermoFisher Scientific</td>
			<td>10828-028</td>
			<td>hiPSC-CM seeding medium</td>
		</tr>
		<tr>
			<td>KOH 8&#160;M</td>
			<td>Sigma-Aldrich</td>
			<td>P4494</td>
			<td>Intracellular pipette solution</td>
		</tr>
		<tr>
			<td>Lambda DG 4</td>
			<td>Sutter Instrument Company</td>
			<td></td>
			<td>Ca2+ transient measurement; ultra-high-speed wavelength switching light source</td>
		</tr>
		<tr>
			<td>Luna-FL automated fluorescence cell counter</td>
			<td>WISBIOMED</td>
			<td>LB-L20001</td>
			<td>Cell counting</td>
		</tr>
		<tr>
			<td>Maestro Pro&#160;MEA system</td>
			<td>Axion Biosystems</td>
			<td></td>
			<td>MEA</td>
		</tr>
		<tr>
			<td>Matrigel Growth Factor Reduced (GFR) Basement Membrane Matrix</td>
			<td>Corning</td>
			<td>356231</td>
			<td>Extracellular matrix medium</td>
		</tr>
		<tr>
			<td>MgATP</td>
			<td>Sigma-Aldrich</td>
			<td>A9187</td>
			<td>Intracellular pipette solution</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma-Aldrich</td>
			<td>M8266</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>S9888</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>NaOH 10&#160;M</td>
			<td>Sigma-Aldrich</td>
			<td>72068</td>
			<td>Tyrode&#8217;s solution</td>
		</tr>
		<tr>
			<td>NIS Elements AR</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pluronic F-127 (20% Solution in DMSO)</td>
			<td>ThermoFisher Scientific</td>
			<td>P3000MP</td>
			<td>Ca2+ transient measurement</td>
		</tr>
		<tr>
			<td>RPMI 1640 medium</td>
			<td>Life Technologies</td>
			<td>11875-119</td>
			<td>hiPSC-CM culture medium</td>
		</tr>
		<tr>
			<td>Sony SI8000 Cell Motion Imaging System</td>
			<td>Sony Biotechnology</td>
			<td></td>
			<td>Contraction motion measurement</td>
		</tr>
		<tr>
			<td>Sutter Micropipette puller</td>
			<td>Sutter Instruments</td>
			<td>P-97</td>
			<td>Patch clamp</td>
		</tr>
		<tr>
			<td>Trypan blue stain</td>
			<td>Life Technologies</td>
			<td>T10282</td>
			<td>Cell counting</td>
		</tr>
	</tbody>
</table>

technical applications of microelectrode array and patch clamp recordings on human induced pluripotent stem cell-derived cardiomyocytes

Drug-induced cardiotoxicity is the leading cause of drug attrition and withdrawal from the market. Therefore, using appropriate preclinical cardiac safety assessment models is a critical step during drug development. Currently, cardiac safety assessment is still highly dependent on animal studies. However, animal models are plagued by poor translational specificity to humans due to species-specific differences, particularly in terms of cardiac electrophysiological characteristics. Thus, there is an urgent need to develop a reliable, efficient, and human-based model for preclinical cardiac safety assessment. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as an invaluable in vitro model for drug-induced cardiotoxicity screening and disease modeling. hiPSC-CMs can be obtained from individuals with diverse genetic backgrounds and various diseased conditions, making them an ideal surrogate to assess drug-induced cardiotoxicity individually. Therefore, methodologies to comprehensively investigate the functional characteristics of hiPSC-CMs need to be established. In this protocol, we detail various functional assays that can be assessed on hiPSC-CMs, including the measurement of contractility, field potential, action potential, and calcium handling. Overall, the incorporation of hiPSC-CMs into preclinical cardiac safety assessment has the potential to revolutionize drug development.

This protocol describes how to measure the contraction motion, field potential, action potential, and Ca2+ transient of hiPSC-CMs. A schematic diagram including the enzymatic digestion, cell seeding, maintenance, and functional assay conduction is shown in Figure 1. The formation of the hiPSC-CM monolayer is necessary for the contraction motion measurement (Figure 2B). A representative trace of the contraction-relaxation motion of hiPSC-CMs is shown i...

Watch this Scientific Journal Video about Technical Applications of Microelectrode Array and Patch Clamp Recordings on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes at JoVE.com

Technical Applications of Microelectrode Array and Patch Clamp Recordings on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as a promising in vitro model for drug-induced cardiotoxicity screening and disease modeling. Here, we detail a protocol for measuring the contractility and electrophysiology of hiPSC-CMs.

Drug-induced cardiotoxicity is the leading cause of drug attrition and withdrawal from the market. Therefore, using appropriate preclinical cardiac safety ...

Cardiac safety assessment is a crucial component during the drug development process. Human iPSC derived cardiomyocytes have proven to be a reliable, efficient, and human based model for pre-clinical cardiac safety assessment. We have established methodologies to comprehensively investigate the functional characteristic of human iPSC derived cardiomyocytes, which are of really important disease modeling, drug induced cardio toxicity screening and precision medicine.The growing incorporation of human iPSC derived cardiomyocytes into the standard pre-clinical safety evaluations process has the potential to improve the accuracy of toxicity prediction of a candidate's compounds. Begin by culturing the human iPSC derived cardiomyocytes for at least 10 days before taking the measurement. Turn on the temperature controller and set it at 37 degrees celsius.Turn on the microscope, camera, and carbon dioxide supply. Fill the water jacket of the plate holder with an appropriate amount of sterile deionized water. Place the 96 well plate on the plate holder, and incubate the cells for at least five minutes.Open the view software, then set the camera frame rate to 75 frames per second, and the video or image resolution to 1024 x 1024 pixels. Apply the auto focus and auto brightness functions, record videos and images of human iPSC derived cardiomyocytes. Carefully place an eight microliter droplet of extra cellular matrix coating solution over the recording electrode area of each well of the 48 well microelectrode array plates.Then add three milliliters of sterile deionized water to the area surrounding the wells to prevent coating solution evaporation. Using a 200 microliter pipette tip, remove most of the extra cellular matrix medium from the well surface within the same single row or column without touching the electrodes. Seed 50, 000 cells per well in an eight microliter droplet of seeding medium over the recording electrode area.Repeat until all wells have been plated with cells. Then incubate the microelectrode array plates in a humidified cell culture incubator. Slowly add 150 microliters of seeding medium to each well of the microelectrode array plates.On day 10 post plating, check the density of spontaneous beating human iPSC CM monolayer under a microscope. Place the 48 well microelectrode array plate in the recording instrument. Ensure that the temperature is 37 degrees celsius and carbon dioxide is 5%Open the navigator software.In the experimental setup window, select cardiac real time configuration and field potential recordings. Apply spontaneous or paste beating configurations. In beat detection parameters, set detection threshold to 300 micro volts, minimum beating period to 250 milliseconds, and maximum beating period to five seconds.Select polynomial regression for field potential duration calculation. Check whether the baseline electrical activity signal is mature and stable, and acquire the baseline cardiac activities for one to three minutes. Perform the recording 10 days post plating.Replace the human iPSC CM maintenance medium with tyrode's solution, and allow the cells to acclimate for 15 minutes. Insert the temperature sensors in the chamber, and put the 35 millimeter dish inside. Adjust the temperature to 37 degrees celsius.Pull the micro pipettes from borosilicate glass capillaries using a micro pipette puller. Fill the micro pipettes with the intracellular solution, and insert them into the holder connected to the head stage of the patch clamp amplifier. Open the acquisition software, load the action potential recording protocol, and select the voltage clamp configuration.Insert the micro pipette into the bath solution, and select appropriate single human iPSC CMs. Adjust and lower the position of the micro pipette next to the selected cell using a micromanipulator. When the pipette tip is inserted into the bath solution, check for pipette resistance on the oscilloscope monitor.Position the pipette close to the cell, and the current pulses will decrease slightly to reflect the increasing seal resistance. Apply gentle suction with negative pressure to increase the resistance. This will form a gigaseal.Then apply the seal function. Apply additional suction to break the membrane to get a whole cell recording configuration. At this point, switch from voltage clamp mode to current clamp mode, or no current injection using the amplifier dialogue.Press the record button to generate and save the action potential recording files. Perform the calcium transient measurement at least 10 days post plating. Prepare fresh tyrode's solution and Fura-2 AM loading solution.Aspirate the human iPSC CM maintenance medium, and wash the chambers with tyrode's solution twice. Apply 100 microliters of Fura-2 AM loading solution and incubate for 10 minutes at room temperature. Replace the Fura-2 AM loading solution with tyrode's solution and incubate for at least five minutes for complete deesterification of Fura-2 AM.Add a drop of immersion oil on the 40x oil immersion objective of an inverted epifluorescence microscope.Place the cell chamber in the stage adaptor of the microscope. Install the temperature controller wires to the bath chamber, and set it to 37 degrees celsius. Install the electrical field stimulation electrodes, and set the pulses at 0.5 hertz with a 20 millisecond duration.Turn on the ultra high speed wavelength switching light source, and set it to 340 nanometers and 380 nanometers fast switching mode. Apply an exposure time of 20 milliseconds for both wavelengths, and a recording time of 20 seconds. Record the video reflecting real time changes of calcium transient, export the data to a spreadsheet for analysis.Human iPSC derived cardiomyocytes monolayer was used for the contraction motion measurement. Analysis of a trace of the contraction relaxation motion using the analyzer software detected the contractions start, contraction peak, contraction end, relaxation peak, and relaxation end. Full coverage of the human iPSC derived cardiomyocytes monolayer was observed on all the electrodes within the microelectrode array plates.The mature waveforms recorded by each electrode reflected the cardiac field potential with identifiable characteristics. After analysis, beat period, field potential duration, and spike amplitude were obtained. Whole cell patch clamp recordings in current clamping mode recorded the spontaneous action potentials of single cardiomyocytes.After analysis, several parameters, including the amplitude, max diastolic potential, and action potential duration were obtained. After the analysis of calcium imaging, F340 by F380 ratio over time was obtained, and raw traces of stimulated calcium transients were plotted. In addition, parameters such as amplitude, diastolic calcium, and calcium decay tau were obtained.It is important to use the human iPSC derived cardiomyocytes that are in good beating conditions, as well as to ensure the high purity of the human iPSC derived cardiomyocytes. This protocol includes four specific techniques to study human iPSC derived cardiomyocyte functionality, other configuration, or automatic whether to study cardiac ionic currents that play a crucial role in cardiac

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Research

JoVE Journal

Medicine

Formation of Human Prostate Epithelium Using Tissue Recombination of Rodent Urogenital Sinus Mesenchyme and Human Stem Cells

Progress in prostate cancer research is severely limited by the availability of human-derived and hormone-na&iuml;ve model systems, which limit our ability to understand genetic and molecular events underlying prostate disease initiation. Toward developing better model systems for studying human prostate carcinogenesis, we and others have taken advantage of the unique pro-prostatic inductive potential of embryonic rodent prostate stroma, termed urogenital sinus mesenchyme (UGSM). When recombined with certain pluripotent cell populations such as embryonic stem cells, UGSM induces the formation of normal human prostate epithelia in a testosterone-dependent manner. Such a human model system can be used to investigate and experimentally test the ability of candidate prostate cancer susceptibility genes at an accelerated pace compared to typical rodent transgenic studies. Since Human embryonic stem cells (hESCs) can be genetically modified in culture using inducible gene expression or siRNA knock-down vectors prior to tissue recombination, such a model facilitates testing the functional consequences of genes, or combinations of genes, which are thought to promote or prevent carcinogenesis.
The technique of isolating pure populations of UGSM cells, however, is challenging and learning often requires someone with previous expertise to personally teach. Moreover, inoculation of cell mixtures under the renal capsule of an immunocompromised host can be technically challenging. Here we outline and illustrate proper isolation of UGSM from rodent embryos and renal capsule implantation of tissue mixtures to form human prostate epithelium. Such an approach, at its current stage, requires in vivo xenografting of embryonic stem cells; future applications could potentially include in vitro gland formation or the use of induced pluripotent stem cell populations (iPSCs).

To unravel the earliest molecular mechanisms underlying prostate cancer initiation, novel and innovative human model systems and approaches are desperately needed. The potential of pre-prostatic urogenital sinus mesenchyme (UGSM) to induce pluripotent stem cell populations to form human prostate epithelium is a powerful experimental tool in prostate research.

Progress in prostate cancer research is severely  limited by the availability of human-derived and hormone-na&iuml;ve model systems,  which limit our ...

Multi-electrode Array Recordings of Human Epileptic Postoperative Cortical Tissue

Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which disrupt normal brain function. Despite treatment with currently available antiepileptic drugs targeting neuronal functions, one third of patients with epilepsy are pharmacoresistant. In this condition, surgical resection of the brain area generating seizures remains the only alternative treatment. Studying human epileptic tissues has contributed to understand new epileptogenic mechanisms during the last 10 years. Indeed, these tissues generate spontaneous interictal epileptic discharges as well as pharmacologically-induced ictal events which can be recorded with classical electrophysiology techniques. Remarkably, multi-electrode arrays (MEAs), which are microfabricated devices embedding an array of spatially arranged microelectrodes, provide the unique opportunity to simultaneously stimulate and record field potentials, as well as action potentials of multiple neurons from different areas of the tissue. Thus MEAs recordings offer an excellent approach to study the spatio-temporal patterns of spontaneous interictal and evoked seizure-like events and the mechanisms underlying seizure onset and propagation. Here we describe how to prepare human cortical slices from surgically resected tissue and to record with MEAs interictal and ictal-like events ex vivo.

We here describe how to perform multi-electrode array recordings of human epileptic cortical tissue. Epileptic tissue resection, slice preparation and multi-electrode array recordings of interictal and ictal events are demonstrated in detail.

Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which ...

Rapid and Efficient Generation of Recombinant Human Pluripotent Stem Cells by Recombinase-mediated Cassette Exchange in the AAVS1 Locus

Even with the revolution of gene-targeting technologies led by CRISPR-Cas9, genetic modification of human pluripotent stem cells&#160;(hPSCs)&#160;is still time consuming. Comparative studies that use recombinant lines with transgenes integrated into safe harbor loci could benefit from approaches that use site-specific targeted recombinases, like Cre or FLPe, which are more rapid and less prone to off-target effects. Such methods have been described, although they do not significantly outperform gene targeting in most aspects. Using Zinc-finger nucleases, we previously created a master cell line in the AAVS1 locus of hPSCs&#160;that contains a GFP-Hygromycin-tk expressing cassette, flanked by heterotypic FRT sequences. Here, we describe the procedures to perform FLPe recombinase-mediated cassette exchange (RMCE) using this line. The master cell line is transfected with a RMCE donor vector, which contains a promoterless Puromycin resistance, and with FLPe recombinase. Application of both a positive (Puromycin) and negative (FIAU) selection program leads to the selection of RMCE without random integrations. RMCE generates fully characterized pluripotent polyclonal transgenic lines in 15 d&#160;with 100% efficiency. Despite the recently described limitations of the AAVS1 locus, the ease of the system paves the way for hPSC transgenesis in isogenic settings, is necessary for comparative studies, and enables semi-high-throughput genetic screens for gain/loss of function analysis that would otherwise be highly time consuming.

Rapid and Efficient Generation of Recombinant Human Pluripotent Stem Cells by Recombinase-mediated Cassette Exchange in the AAVS1 Locus

Here we report a rapid and efficient gene editing method based on RMCE in the AAVS1 locus of human Pluripotent Stem Cells (hPSCs) that improves upon previously described systems. Using this technique, isogenic lines can be rapidly and reliably generated for proper comparative studies, facilitating transgenesis-mediated research with hPSCs.

Even with the revolution of gene-targeting technologies led by CRISPR-Cas9, genetic modification of human pluripotent stem cells&#160;(hPSCs)&#160;is ...

Targeted and Selective Treatment of Pluripotent Stem Cell-derived Teratomas Using External Beam Radiation in a Small-animal Model

The growing number of victims of &#34;stem cell tourism,&#34; the unregulated transplantation of stem cells worldwide, has raised concerns about the safety of stem cell transplantation. Although the transplantation of differentiated rather than undifferentiated cells is common practice, teratomas can still arise from the presence of residual undifferentiated stem cells at the time of transplant or from spontaneous mutations in differentiated cells. Because stem cell therapies are often delivered into anatomically sensitive sites, even small tumors can be clinically devastating, resulting in blindness, paralysis, cognitive abnormalities, and cardiovascular dysfunction. Surgical access to these sites may also be limited, leaving patients with few therapeutic options. Controlling stem cell misbehavior is, therefore, critical for the clinical translation of stem cell therapy.
External beam radiation offers an effective means of delivering targeted therapy to decrease the teratoma burden while minimizing injury to surrounding organs. Additionally, this method avoids genetic manipulation or viral transduction of stem cells-which are associated with additional clinical safety and efficacy concerns. Here, we describe a protocol to create pluripotent stem cell-derived teratomas in mice and to apply external beam radiation therapy to selectively ablate these tumors in vivo.

Research on treatment strategies for pluripotent stem cell-derived teratomas is important for the clinical translation of stem cell therapy. Here, we describe a protocol to, first, generate stem cell-derived teratomas in mice and, then, to selectively target and treat these tumors in vivo using a small-animal irradiator.

The growing number of victims of &#34;stem cell tourism,&#34; the unregulated transplantation of stem cells worldwide, has raised concerns about the ...

Sarcomere Shortening of Pluripotent Stem Cell-Derived Cardiomyocytes using Fluorescent-Tagged Sarcomere Proteins.

Pluripotent stem cell-derived cardiomyocytes (PSC-CMs) can be produced from both embryonic and induced pluripotent stem (ES/iPS) cells. These cells provide promising sources for cardiac disease modeling. For cardiomyopathies, sarcomere shortening is one of the standard physiological assessments that are used with adult cardiomyocytes to examine their disease phenotypes. However, the available methods are not appropriate to assess the contractility of PSC-CMs, as these cells have underdeveloped sarcomeres that are invisible under phase-contrast microscopy. To address this issue and to perform sarcomere shortening with PSC-CMs, fluorescent-tagged sarcomere proteins and fluorescent live-imaging were used. Thin Z-lines and an M-line reside at both ends and the center of a sarcomere, respectively. Z-line proteins &#8212;&#160;&#945;-Actinin (ACTN2), Telethonin (TCAP), and actin-associated LIM protein (PDLIM3) &#8212; and one M-line protein &#8212; Myomesin-2 (Myom2) &#8212;&#160;were tagged with fluorescent proteins. These tagged proteins can be expressed from endogenous alleles as knock-ins or from adeno-associated viruses (AAVs). Here, we introduce the methods to differentiate mouse and human pluripotent stem cells to cardiomyocytes, to produce AAVs, and to perform and analyze live-imaging. We also describe the methods for producing polydimethylsiloxane (PDMS) stamps for a patterned culture of PSC-CMs, which facilitates the analysis of sarcomere shortening with fluorescent-tagged proteins. To assess sarcomere shortening, time-lapse images of the beating cells were recorded at a high framerate (50-100 frames per second) under electrical stimulation (0.5-1 Hz). To analyze sarcomere length over the course of cell contraction, the recorded time-lapse images were subjected to SarcOptiM, a plug-in for ImageJ/Fiji. Our strategy provides a simple platform for investigating cardiac disease phenotypes in PSC-CMs.

This method can be used to examine sarcomere shortening using pluripotent stem cell-derived cardiomyocytes with fluorescent-tagged sarcomere proteins.

Pluripotent stem cell-derived cardiomyocytes (PSC-CMs) can be produced from both embryonic and induced pluripotent stem (ES/iPS) cells. These cells ...

Directed Induction of Retinal Organoids from Human Pluripotent Stem Cells

Retinal cell transplantation is a promising therapeutic approach, which could restore the retinal architecture and stabilize or even improve the visual capabilities to the degenerated retina. Nevertheless, progress in cell replacement therapy presently faces the challenges of requiring an off-the-shelf source of high quality and standardized human retinas. Therefore, an easy and stable protocol is needed for the experiments. Here, we develop an optimized protocol, based on a self-organizing method with the use of exogenous molecules and reagent A as well as manual excision to generate the three-dimensional human retina organoids (RO). The human Pluripotent Stem Cells (PSCs)-derived RO expresses specific markers for photoreceptors. With the addition of COCO, a multifunctional antagonist, the differentiation efficiency of photoreceptor precursors and cones is significantly increased. The efficient use of this system, which has the benefits of cell lines and primary cells, and without the sourcing issues associated with the latter, could produce confluent retinal cells, especially photoreceptors. Thus, the differentiation of PSCs to RO provides an optimal and biorelevant platform for disease modelling, drug screening and cell transplantation.

Using a self-organizing method, we develop a protocol with the addition of COCO that could significantly increase the generation of photoreceptors.

Retinal cell transplantation is a promising therapeutic approach, which could restore the retinal architecture and stabilize or even improve the visual ...

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice

The sinoatrial node (SAN), located in the right atrium, contains the pacemaker cells of the heart, and dysfunction of this region can cause tachycardia or bradycardia. Reliable identification of cardiac pacemaking defects requires the measurement of intrinsic heart rates by largely preventing the influence of the autonomic nervous system, which can mask rate deficits. Traditional methods to analyze intrinsic cardiac pacemaker function include drug-induced autonomic blockade to measure in vivo heart rates, isolated heart recordings to measure intrinsic heart rates, and sinoatrial strip or single-cell patch-clamp recordings of sinoatrial pacemaker cells to measure spontaneous action potential firing rates. However, these more traditional techniques can be technically challenging and difficult to perform. Here, we present a new methodology to measure intrinsic cardiac firing rate by performing microelectrode array (MEA) recordings of whole-mount sinoatrial node preparations from mice. MEAs are composed of multiple microelectrodes arranged in a grid-like pattern for recording in vitro extracellular field potentials. The method described herein has the combined advantage of being relatively faster, simpler, and more precise than previous approaches for recording intrinsic heart rates, while also allowing easy pharmacological interrogation.

This protocol aims to describe a new methodology to measure intrinsic cardiac firing rate using microelectrode array recording of the whole sinoatrial node tissue to identify pacemaking defects in mice. Pharmacological agents can also be introduced in this method to study their effects on intrinsic pacemaking.

The sinoatrial node (SAN), located in the right atrium, contains the pacemaker cells of the heart, and dysfunction of this region can cause tachycardia or ...

Ultrasound-Guided Induced Pluripotent Stem Cell-Derived Cardiomyocyte Implantation in Myocardial Infarcted Mice

The key objective of cell therapy after myocardial infarction (MI) is to effectively enhance the cell grafted rate, and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a promising cell source for cardiac repair after ischemic damage. However, a low grafted rate is a significant obstacle for effective cardiac tissue regeneration after transplantation. This protocol shows that multiple hiPSC-CM ultrasound-guided percutaneous injections into an MI area effectively increase cell transplantation rates. The study also describes the entire hiPSC-CM culture process, pretreatment, and ultrasound-guided percutaneous delivery methods. In addition, the use of human mitochondrial DNA help detect the absence of hiPSC-CMs in other mouse organs. Lastly, this paper describes the changes in cardiac function, angiogenesis, cell size, and apoptosis at the infarcted border zone in mice 4 weeks after cell delivery. It can be concluded that echocardiography-guided percutaneous injection of the left ventricular myocardium is a feasible, relatively invasive, satisfactory, repeatable, and effective cellular therapy.

Ultrasound-guided cell delivery around the site of myocardial infarction in mice is a safe, effective, and convenient way of cell transplantation.

The key objective of cell therapy after myocardial infarction (MI) is to effectively enhance the cell grafted rate, and human induced pluripotent stem ...

Laser-Induced Action Potential-Like Measurements of Cardiomyocytes on Microelectrode Arrays for Increased Predictivity of Safety Pharmacology

Life-threatening drug-induced cardiac arrhythmia is often preceded by prolonged cardiac action potentials (AP), commonly accompanied by small proarrhythmic membrane potential fluctuations. The shape and time course of the repolarizing fraction of the AP can be pivotal for the presence or absence of arrhythmia.
Microelectrode arrays (MEA) allow easy access to cardiotoxic compound effects via extracellular field potentials (FP). Although a powerful and well-established tool in research and cardiac safety pharmacology, the FP waveform does not allow to infer the original AP shape due to the extracellular recording principle and the resulting intrinsic alternating current (AC) filtering.
A novel device, described here, can repetitively open the membrane of cardiomyocytes cultivated on top of the MEA electrodes at multiple cultivation time points, using a highly focused nanosecond laser beam. The laser poration results in transforming the electrophysiological signal from FP to intracellular-like APs (laser-induced AP, liAP) and enables the recording of transcellular voltage deflections. This intracellular access allows a better description of the AP shape and a better and more sensitive classification of proarrhythmic potentials than regular MEA recordings. This system is a revolutionary extension to the existing electrophysiological methods, permitting accurate evaluation of cardiotoxic effect with all advantages of MEA-based recordings (easy, acute, and chronic experiments, signal propagation analysis, etc.).

The combination of laser poration and microelectrode arrays (MEA) allows action potential-like recordings of cultivated primary and stem cell-derived cardiomyocytes. The waveform shape provides superior insight into test compounds' mode of action than standard recordings. It links patch-clamp and MEA readout to further optimize cardio safety research in the future.

Life-threatening drug-induced cardiac arrhythmia is often preceded by prolonged cardiac action potentials (AP), commonly accompanied by small ...

Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique

Potassium channels on the myocardial cell membrane play an important role in the regulation of cell electrophysiological activities. Being one of the main ion channels, voltage-gated potassium (Kv) channels are closely associated with some serious heart diseases, such as drug-induced myocardial damage and myocardial infarction. In the present study, the whole-cell patch-clamp technique was employed to determine the effects of 1.5 mM 4-aminopyridine (4-AP, a broad-spectrum potassium channel inhibitor) and aconitine (AC, 25 &#181;M, 50 &#181;M, 100 &#181;M, and 200 &#181;M) on the Kv channel current (IKv) in H9c2 cardiomyocytes. It was found that 4-AP inhibited the IKv by about 54%, while the inhibitory effect of AC on the IKv showed a dose-dependent trend (no effect for 25 &#181;M, 30% inhibitory rate for 50 &#181;M, 46% inhibitory rate for 100 &#181;M and 54% inhibitory rate for 200 &#181;M). Due to the characteristics of higher sensitivity and precision, this technique will promote the exploration of cardiotoxicity and the pharmacological effects of ethnomedicine targeting ion channels.

Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique

The present protocol describes an efficient method for the real-time and dynamic acquisition of voltage-gated potassium (Kv) channel currents in H9c2 cardiomyocytes using the whole-cell patch-clamp technique.

Potassium channels on the myocardial cell membrane play an important role in the regulation of cell electrophysiological activities. Being one of the main ...