This work was supported by the E.U. (STREP Project 241577 "BIG HEART," 7th European Framework Program, CP), Menarini International Operations Luxembourg (AM), Telethon GGP07133 (CP) and Gilead Sciences (AM).

The experimental protocols on human tissue were approved by the ethical committee of Careggi University-Hospital (2006/0024713; renewed May 2009). Each patient gave written informed consent.
1. Solutions and Equipment Preparation
Solutions are described in Table 1. A simplified flowchart of the cell isolation procedure is found in Figure 1.
<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td colspan="2">Solution</td>
			<td>CP</td>
			<td>DB</td>
			<td>KB</td>
			<td>TB</td>
			<td>PS</td>
			<td>EB1</td>
			<td>EB2</td>
		</tr>
		<tr>
			<td rowspan="23">Reagent (mM)</td>
			<td>KH2PO4</td>
			<td>50</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>8</td>
			<td>1.2</td>
			<td>5</td>
			<td></td>
			<td></td>
			<td>1.2</td>
			<td>1.2</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>10</td>
			<td></td>
			<td></td>
			<td>10</td>
			<td>10</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>adenosine</td>
			<td>5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>glucose</td>
			<td>140</td>
			<td>10</td>
			<td>20</td>
			<td>10</td>
			<td></td>
			<td>10</td>
			<td>10</td>
		</tr>
		<tr>
			<td>mannitol</td>
			<td>100</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>taurine</td>
			<td>10</td>
			<td>20</td>
			<td>5</td>
			<td></td>
			<td></td>
			<td>20</td>
			<td>20</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td></td>
			<td>113</td>
			<td></td>
			<td>136</td>
			<td></td>
			<td>113</td>
			<td>113</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td></td>
			<td>4.7</td>
			<td>85</td>
			<td>5.4</td>
			<td>25</td>
			<td>4.7</td>
			<td>4.7</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td></td>
			<td></td>
			<td></td>
			<td>1.2</td>
			<td>5</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td></td>
			<td>0.6</td>
			<td>30</td>
			<td></td>
			<td></td>
			<td>0.6</td>
			<td>0.6</td>
		</tr>
		<tr>
			<td>Na2HPO4</td>
			<td></td>
			<td>0.6</td>
			<td></td>
			<td></td>
			<td></td>
			<td>0.6</td>
			<td>0.6</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td></td>
			<td>12</td>
			<td></td>
			<td></td>
			<td></td>
			<td>12</td>
			<td>12</td>
		</tr>
		<tr>
			<td>KHCO3</td>
			<td></td>
			<td>10</td>
			<td></td>
			<td></td>
			<td></td>
			<td>10</td>
			<td>10</td>
		</tr>
		<tr>
			<td>Na-pyruvate</td>
			<td></td>
			<td>4</td>
			<td></td>
			<td></td>
			<td></td>
			<td>4</td>
			<td>4</td>
		</tr>
		<tr>
			<td>BDM</td>
			<td></td>
			<td>10</td>
			<td></td>
			<td></td>
			<td></td>
			<td>10</td>
			<td>10</td>
		</tr>
		<tr>
			<td>BHBA</td>
			<td></td>
			<td></td>
			<td>5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>succinic acid</td>
			<td></td>
			<td></td>
			<td>5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td></td>
			<td></td>
			<td>0.5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>K2-ATP</td>
			<td></td>
			<td></td>
			<td>2</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pyruvic acid</td>
			<td></td>
			<td></td>
			<td>5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>creatine</td>
			<td></td>
			<td></td>
			<td>5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>KMES</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>115</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td rowspan="2">Enzymes (U/ml)</td>
			<td>Collagenase Type V</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>250</td>
			<td>250</td>
		</tr>
		<tr>
			<td>Protease Type XXIV</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>4</td>
			<td></td>
		</tr>
		<tr>
			<td>pH</td>
			<td></td>
			<td>7.4 KOH</td>
			<td>7.3 NaOH</td>
			<td>7.1 KOH</td>
			<td>7.35 NaOH</td>
			<td>7.2 KOH</td>
			<td>7.3 NaOH</td>
			<td>7.3 NaOH</td>
		</tr>
	</tbody>
</table>
Table 1. Solutions used for specimen collection, cell isolation and functional characterization of myocytes. CP= cardioplegic solution; DB=dissociation buffer; KB= Kraft-Bruhe solution; TB=Tyrode buffer; PS=pipette solution; EB1= enzyme buffer 1; EB2= enzyme buffer 2.
<ol>
	<li>Prepare cardioplegic (CP) solution. CP solution can be stored at 4 &#176;C for up to 1 week.</li>
	<li>Prepare Ca2+-free dissociation buffer (DB). This solution should be used within the day.</li>
	<li>Prepare Kraft-Bruhe (KB) solution. KB solution can be stored at 4 &#176;C for up to 1 week.</li>
	<li>Prepare Ca2+-free Tyrode buffer (TB). This solution should be used within the day.</li>
	<li>Filter all solutions using syringe filters prior to use.</li>
	<li>Prepare the digestion device (Figure&#160;2), a scraping container made of two facing brushes of silicone elastomer, one of which rotated by an electric motor. The digestion device is custom made. Details on the digestion device are in Figure&#160;8; images of the device are in Figures 2C and 2D. Wash the tissue chamber with 70% ethanol and water.</li>
</ol>
2. Collection and Processing of Myocardial Samples
<ol>
	<li>Pour 40 ml of cardiplegic (CP) solution in a 50 ml tube and store it in ice for specimen transportation from the operative room to the cell isolation lab.</li>
	<li>Collect the ventricular myocardial specimen from the operative room immediately after excision, wash it with ice cold CP solution and store it in the tube. Use endocardial specimens excised from the upper inter ventricular septum during open heart surgery, weighting &#62;100 mg.</li>
	<li>Rapidly transfer the specimen to the lab area; start specimen processing within 10 min&#160;from specimen excision.</li>
	<li>While keeping the specimen in ice cold CP buffer, carefully remove the endocardial fibrotic layer using fine scissors under a stereomicroscope; afterwards, cut the myocardial tissue to small pieces (2-3 mm long). Depending on tissue sample size, cut a total amount of ventricular myocardium between 100 mg and 1 g for each isolation.</li>
	<li>Upon completion of tissue mincing, transfer the myocardial chunks into the digestion device, with clean ice cold CP solution. Avoid filling the whole volume between the two silicon brushes (3-4 ml) with myocardial chunks, using no more than 1 g of total tissue.</li>
</ol>
3. Washing and Digestion of Myocardial Chunks
<ol>
	<li>After the chunks are transferred into the scraping chamber of the digestion device, change the CP buffer in the chamber with cold Ca2+-free dissociation buffer (DB).</li>
	<li>Place the digestion device in a thermostatic bath, in order for the chamber to be in contact with the heated water in the bath (Figure 1). Set the bath to 37.5 &#176;C and turn it on, in order to slowly raise the temperature of the tissue chamber. Turn on the motor of the digestion device, setting the rotation speed to 1 revolution/second.</li>
	<li>Perform 3 washing cycles with DB, changing the solution in the chamber with clean DB every 8 min. The DB is warmed (37 &#176;C) and oxygen saturated before getting in contact with the myocardial chunks.</li>
	<li>Prepare enzyme buffer 1 (EB1) by adding 250 U/ml of Collagenase Type V and 4 U/ml Protease Type XXIV to DB solution. Prepare enzyme buffer 2 (EB2) by adding 250 U/ml Collagenase Type V to DB solution. Warm up (37 &#176;C) and oxygenate EB1 and EB2.</li>
	<li>Perform two 12 min cycles of digestion in the rotating digestion device with 100% oxygenated EB1 (at 37 &#176;C). At each cycle, use ~3 ml of EB1. Remove the solution by pipette aspiration and discard it after each cycle.</li>
	<li>Prepare 6 15 ml tubes for cell collection and ~80 ml of cold (4 &#176;C) KB solution for eluting the buffers.</li>
	<li>Perform a first 15 min&#160;digestion cycle with 3 ml 100% oxygenated EB2 at 37 &#176;C. After the digestion cycle, collect the solution containing the first dissociated myocytes in a 15 ml tube and dilute the cell suspension with 12 ml cold KB solution. Store the tube flat at room temperature.</li>
	<li>Dilute the remaining EB2 solution with an equal amount of DB in order to halve the concentration of collagenase V for the following digestion cycles.</li>
	<li>Perform other 5 12 min&#160;digestion cycles with 3 ml EB2 at 37 &#176;C; after each of them collect of myocyte containing buffer in a 15 ml conical tube and dilute it with 12 ml KB solution. Store the 6 cell containing tubes at room temperature for 30 min.</li>
</ol>
4. Cell Resuspension and Ca2+ Readaptation
<ol>
	<li>Add 1 mg/ml&#160;bovine serum albumin (BSA) to 20 ml Ca2+-free Tyrode buffer (TB). Filter the solution.</li>
	<li>Centrifuge the six myocyte containing conical tubes at 100 x g for 5 min to force myocytes to settle. Remove the supernatant and resuspend the cells in each tube with a variable amount (1-3 ml, depending on the yield) of BSA containing TB at RT.</li>
	<li>Gradually increase Ca2+ concentration in the cell containing buffer by adding small aliquots of 100 mmol/L&#160;CaCl2 solution. In the first and second steps Ca2+ concentration is raised up to 50 &#956;mol/L and 100 &#956;mol/L, respectively. The following Ca2+ addition steps are performed every 5 min&#160;and the concentration is raised by 100 &#956;mol/L at each step to a final concentration of 0.9 mmol/L.</li>
	<li>Assess the yield of the isolation procedure. Transfer 0.5 ml of myocyte containing solution onto the glass bottom chamber of a microscope. Evaluate 15 microscope fields at 10x objective magnification and calculate the percentage of healthy myocytes (e.g. rod shaped cells with clear striations and no significant inclusions, Figure&#160;2). The expected yield is around 20 %.</li>
</ol>
5. Functional Evaluation of Isolated Cardiomyocytes.
The following protocol is an example of human cardiomyocyte functional assessment including simultaneous recordings of action potentials and intracellular Ca2+ fluxes.
<ol>
	<li>Prepare pipette solution (PS) for patch clamp experiments in perforated patch configuration. The solution can be stored at -20 &#176;C for up to 3 months.</li>
	<li>Add 1.8 mmol/L CaCl2 to Ca2+-free Tyrode buffer (TB). Use this solution for superfusion of cardiomyocytes during patch clamp/fluorescence experiments.</li>
	<li>Transfer 1 ml&#160;of cell suspension to a 1.5 ml tube and add 10 &#956;mol/L Fluoforte and 10 &#956;l Powerload Concentrate. Incubate for 30 min at RT. Afterwards, set the tube in vertical position and leave the cell to settle for 5 min; resuspend the cells in Ca2+&#160;containing TB.</li>
	<li>Transfer 0.25 ml of cell suspension to a small (0.5 ml), temperature controlled microscope mounted recording chamber, superfused by gravity with a heated microperfusor system at a flow rate of 0.3 ml/min (temperature: 37 &#177; 0.5 &#176;C).</li>
	<li>Using a micropipette puller, prepare patch clamp pipettes with a tip diameter of 3 to 5 &#956;m and a resistance of 3 to 4.5 M when filled with PS.</li>
	<li>Add amphotericin B to a batch of PS (250 &#956;g/ml) and use it to fill the electrodes.&#160;</li>
	<li>Select a rod shaped cell with clear striations, devoid of inclusions, form the giga seal and wait 5 to 10 min, until access resistance drops below 20 M&#937;.</li>
	<li>Elicit action potentials in current clamp mode using short pulses (&#60; 3 msec) at different frequencies of stimulation (0.2 Hz, 0.5 Hz and 1 Hz, 1 min&#160;at each frequency). During the recording phase, turn on bright field illumination at 492 &#177; 3 nm and detect Fluoforte fluorescence at 505-520 nm. Acquire fluorescence and membrane potential signals using Digidata 1440A and pClamp 10.0 software. Repeat the recording sequence multiple times if needed; however, keep the total recording time below 15 min&#160;for each cell.</li>
</ol>

<ol>
	<li>Dow, J. W., Harding, N. G., Powell, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolated+cardiac+myocytes.+I.+Preparation+of+adult+myocytes+and+their+homology+with+the+intact+tissue.">Isolated cardiac myocytes. I. Preparation of adult myocytes and their homology with the intact tissue.</a> Cardiovascular Research. 15, 483-514 (1981).</li><li>Dow, J. W., Harding, N. G., Powell, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolated+cardiac+myocytes.+II.+Functional+aspects+of+mature+cells.">Isolated cardiac myocytes. II. Functional aspects of mature cells.</a> Cardiovascular Research. 15, 549-579 (1981).</li><li>Harding, S. E., 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=Species+dependence+of+contraction+velocity+in+single+isolated+cardiac+myocytes.">Species dependence of contraction velocity in single isolated cardiac myocytes.</a> Cardioscience. 1, 49-53 (1990).</li><li>Bustamante, J. O., Watanabe, T., Murphy, D. A., McDonald, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+single+atrial+and+ventricular+cells+from+the+human+heart.">Isolation of single atrial and ventricular cells from the human heart.</a> Canadian Medical Association Journal. 126, 791-793 (1982).</li><li>Beuckelmann, D. J., Nabauer, M., Erdmann, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characteristics+of+calcium-current+in+isolated+human+ventricular+myocytes+from+patients+with+terminal+heart+failure.">Characteristics of calcium-current in isolated human ventricular myocytes from patients with terminal heart failure.</a> Journal of Molecular and Cellular Cardiology. 23, 929-937 (1991).</li><li>Beuckelmann, D. J., Nabauer, M., Erdmann, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+calcium+handling+in+isolated+ventricular+myocytes+from+patients+with+terminal+heart+failure.">Intracellular calcium handling in isolated ventricular myocytes from patients with terminal heart failure.</a> Circulation. 85, 1046-1055 (1992).</li><li>Cohen, N. M., Lederer, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+current+in+single+human+cardiac+myocytes.">Calcium current in single human cardiac myocytes.</a> Journal of Cardiovascular Electrophysiology. 4, 422-437 (1993).</li><li>Beuckelmann, D. J., Nabauer, M., Erdmann, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alterations+of+K++currents+in+isolated+human+ventricular+myocytes+from+patients+with+terminal+heart+failure.">Alterations of K+ currents in isolated human ventricular myocytes from patients with terminal heart failure.</a> Circulation Research. 73, 379-385 (1993).</li><li>Virag, 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=The+slow+component+of+the+delayed+rectifier+potassium+current+in+undiseased+human+ventricular+myocytes.">The slow component of the delayed rectifier potassium current in undiseased human ventricular myocytes.</a> Cardiovascular Research. 49, 790-797 (2001).</li><li>Nanasi, P. P., Varro, A., Lathrop, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+human+ventricular+and+atrial+cardiomyocytes:+technical+note.">Isolation of human ventricular and atrial cardiomyocytes: technical note.</a> Cardioscience. 4, 111-116 (1993).</li><li>Benitah, J. 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=Slow+inward+current+in+single+cells+isolated+from+adult+human+ventricles.+Pflugers+Archiv.">Slow inward current in single cells isolated from adult human ventricles. Pflugers Archiv.</a> European Journal of Physiology. 421, 176-187 (1992).</li><li>Verkerk, A. O., 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=Ionic+mechanism+of+delayed+afterdepolarizations+in+ventricular+cells+isolated+from+human+end-stage+failing+hearts.">Ionic mechanism of delayed afterdepolarizations in ventricular cells isolated from human end-stage failing hearts.</a> Circulation. 104, 2728-2733 (2001).</li><li>Cerbai, E., 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=Characterization+of+the+hyperpolarization-activated+current,+I(f),+in+ventricular+myocytes+from+human+failing+heart.">Characterization of the hyperpolarization-activated current, I(f), in ventricular myocytes from human failing heart.</a> Circulation. 95, 568-571 (1997).</li><li>Kohncke, 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=Isolation+and+kv+channel+recordings+in+murine+atrial+and+ventricular+cardiomyocytes.">Isolation and kv channel recordings in murine atrial and ventricular cardiomyocytes.</a> Journal of Visualized Experiments: JoVE. , (2013).</li><li>Tomaselli, G. F., Marban, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophysiological+remodeling+in+hypertrophy+and+heart+failure.">Electrophysiological remodeling in hypertrophy and heart failure.</a> Cardiovascular Research. 42, 270-283 (1999).</li><li>Maron, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypertrophic+cardiomyopathy:+a+systematic+review.">Hypertrophic cardiomyopathy: a systematic review.</a> JAMA: The Journal of the American Medical Association. 287, 1308-1320 (2002).</li><li>Olivotto, 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=The+many+faces+of+hypertrophic+cardiomyopathy:+from+developmental+biology+to+clinical+practice.">The many faces of hypertrophic cardiomyopathy: from developmental biology to clinical practice.</a> Journal of Cardiovascular Translational Research. 2, 349-367 (2009).</li><li>Maron, M. 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=Hypertrophic+cardiomyopathy+is+predominantly+a+disease+of+left+ventricular+outflow+tract+obstruction.">Hypertrophic cardiomyopathy is predominantly a disease of left ventricular outflow tract obstruction.</a> Circulation. 114, 2232-2239 (2006).</li><li>Peeters, G. 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=Method+for+isolation+of+human+ventricular+myocytes+from+single+endocardial+and+epicardial+biopsies.">Method for isolation of human ventricular myocytes from single endocardial and epicardial biopsies.</a> The American Journal of Physiology. 268, 1757-1764 (1995).</li><li>Lippiat, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole-cell+recording+using+the+perforated+patch+clamp+technique.">Whole-cell recording using the perforated patch clamp technique.</a> Methods Mol Biol. 491, 141-149 (2008).</li><li>Coppini, R., 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=Late+sodium+current+inhibition+reverses+electromechanical+dysfunction+in+human+hypertrophic+cardiomyopathy.">Late sodium current inhibition reverses electromechanical dysfunction in human hypertrophic cardiomyopathy.</a> Circulation. 127, 575-584 (2013).</li><li>Kuusisto, J., 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=Low-grade+inflammation+and+the+phenotypic+expression+of+myocardial+fibrosis+in+hypertrophic+cardiomyopathy.">Low-grade inflammation and the phenotypic expression of myocardial fibrosis in hypertrophic cardiomyopathy.</a> Heart. 98, 1007-1013 (2012).</li><li>Yan, G. 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=Phase+2+early+afterdepolarization+as+a+trigger+of+polymorphic+ventricular+tachycardia+in+acquired+long-QT+syndrome+:+direct+evidence+from+intracellular+recordings+in+the+intact+left+ventricular+wall.">Phase 2 early afterdepolarization as a trigger of polymorphic ventricular tachycardia in acquired long-QT syndrome : direct evidence from intracellular recordings in the intact left ventricular wall.</a> Circulation. 103, 2851-2856 (2001).</li><li>Yue, L., Feng, J., Li, G. R., Nattel, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transient+outward+and+delayed+rectifier+currents+in+canine+atrium:+properties+and+role+of+isolation+methods.">Transient outward and delayed rectifier currents in canine atrium: properties and role of isolation methods.</a> The American Journal of Physiology. 270, 2157-2168 (1996).</li><li>Li, G. R., Feng, J., Yue, L., Carrier, M., Nattel, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+two+components+of+delayed+rectifier+K++current+in+human+ventricular+myocytes.">Evidence for two components of delayed rectifier K+ current in human ventricular myocytes.</a> Circulation research. 78, 689-696 (1996).</li><li>Viswanathan, P. C., Shaw, R. M., Rudy, Y. <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+IKr+and+IKs+heterogeneity+on+action+potential+duration+and+its+rate+dependence:+a+simulation+study.">Effects of IKr and IKs heterogeneity on action potential duration and its rate dependence: a simulation study.</a> Circulation. 99, 2466-2474 (1999).</li><li>Volders, P. 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=Probing+the+contribution+of+IKs+to+canine+ventricular+repolarization:+key+role+for+beta-adrenergic+receptor+stimulation.">Probing the contribution of IKs to canine ventricular repolarization: key role for beta-adrenergic receptor stimulation.</a> Circulation. 107, 2753-2760 (2003).</li><li>Sanguinetti, M. C., Jurkiewicz, N. K., Scott, A., Siegl, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isoproterenol+antagonizes+prolongation+of+refractory+period+by+the+class+III+antiarrhythmic+agent+E-4031+in+guinea+pig+myocytes.+Mechanism+of+action.">Isoproterenol antagonizes prolongation of refractory period by the class III antiarrhythmic agent E-4031 in guinea pig myocytes. Mechanism of action.</a> Circulation Research. 68, 77-84 (1991).</li><li>Coppini, R., 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=A+translational+approach+to+treatment+of+hypertrophic+cardiomyopathy:+pre-clinical+rationale+and+design+of+a+prospective+randomized+pilot+trial+with+ranolazine.">A translational approach to treatment of hypertrophic cardiomyopathy: pre-clinical rationale and design of a prospective randomized pilot trial with ranolazine.</a> Circulation. 125, 1 (2012).</li></ol>

The authors declare that they have no competing financial interests.

We have described and validated a method to isolate viable myocytes from surgical samples of human ventricular myocardium. Starting from previously described protocols that had been successfully used to isolated cells from atrial surgical samples, the technique to allow separation of single viable myocytes from diseased ventricular myocardium was developed and fine tuned. Early reports showed that isolation of single cardiomyocytes from chunks of atrial and ventricular tissue selectively impaired repolarizing potassium c...

Dissection of the electrophysiological properties of the myocardium has progressed markedly after the development of techniques for single cardiac myocyte isolation. Recent advancements in the understanding of cardiac Excitation Contraction Coupling (EC-Coupling) have also been made possible by the capability of isolating viable single cardiomyocytes that retain all the physiological properties of the intact tissue. Patch clamp methods are routinely employed to study the function and pharmacological modulation of cardiac sarcolemmal ion currents. Recordings of intracellular calcium dynamics with Ca2+ sensitive dyes are also regularly performed on single cardiac myocytes from a variety of healthy and diseased models, providing vital data on the physiology of EC-Coupling as well as on the pathological alterations of intracellular Ca2+ homeostasis leading to mechanical impairment and increased arrhythmogenic burden in cardiac diseases. Information from these studies is critical for understanding the electrophysiological and mechanical effects of drugs in the clinical setting. However, there are species specific differences in the transmembrane currents and in the EC-Coupling proteins that account for specific features of cardiac action potential and cardiac mechanics. Thus, while studies of myocytes isolated from non human mammals have elucidated the biophysical properties and physiological roles of specific transmembrane ion channels and EC-Coupling proteins, they do not necessarily provide relevant models of human cardiac myocytes. Isolation of viable myocytes from human myocardium is therefore essential to fully understand the pathophysiology of cardiac diseases and validate novel therapeutic approaches.
Human atrial tissue is readily available as atrial appendages are often discarded during surgical procedures. Initial quantitative studies of adult human cardiac action potentials and ionic currents employed enzymatically isolated atrial cells1-4. Recordings of action potentials or currents from isolated adult human ventricular cells have been subsequently reported3,5-10. Most of these studies have used cells obtained from explanted hearts and utilized either collagenase perfusion of a coronary artery segment or exposure of relatively large quantities of excised tissue to collagenase to obtain isolated cells. These studies allowed a detailed characterization of a number of transmembrane ion currents from human ventricular cardiomyocytes from healthy hearts and from patients with terminal heart failure. Recordings of L-type Ca2+ current (ICa-L)5-7, transient outward potassium current (Ito)8, inward rectifier potassium current (I&#954;1)8, the different components of delayed rectifier potassium current (I&#954;)9 have been reported. Advances and refining of the isolation procedure10, allowed a clear characterization of the ionic basis of the increased arrhythmogenic potential in terminal heart failure, comprising action potential prolongation11, delayed after depolarizations12 and increased funny current13 leading to diastolic depolarization and premature beats.
Adult cardiac myocytes are normally isolated from small animals by retrograde perfusion of the whole heart with various enzyme mixtures, a technique that produces high yields of Ca2+-tolerant cells14. Isolation of cardiac myocytes from fragments of tissue is inherently less successful probably because of the limited access of enzymes to individual myocytes compared with that achieved by perfusion of coronary arteries. Because of the very limited availability of unused donor hearts, the only practical way to obtain normal human ventricular cells on a regular basis is by enzymatic digestion of the often very small tissue fragments excised during elective surgical procedures. The only human disease model that has been thoroughly characterized at cell level is terminal heart failure, due to the accessibility to transplanted hearts. However, terminal heart failure occurs in a minority of patients and often involves a common pathway of severe remodeling of myocardial cells, which is relatively independent of the underlying cause15. The ability to assess the function of single cardiomyocytes from patients at an earlier non failing stage of disease is crucial to understand the specific pathophysiology of different inherited or acquired conditions. Hypertrophic cardiomyopathy (HCM) is a telling example. HCM is a common (1/500 individuals) inheritable cardiac condition characterized by cardiac hypertrophy, increased arrhythmogenic risk and contractile alterations due to outflow tract obstruction and diastolic dysfunction16. Cardiomyocytes from HCM hearts undergo a complex remodeling processes involving changes in cell structure (hypertrophy, myofibrillar disarray) and EC-Coupling17. However, most information of myocyte dysfunction in HCM has come from transgenic animal models. Since only a minority of HCM patients evolves toward terminal heart failure and requires cardiac transplantation, HCM hearts are very rarely available for cell isolation with standard methods. However, at least 30% of HCM patients develop obstructive symptoms due to massive septal hypertrophy altering outflow tract blood flow during systole (HCM)18. The most effective available therapeutic option for the relief of obstruction in HCM is surgical septal myectomy: during this surgical procedure, a variable sized portion of upper septum is removed by trans aortic approach. This portion of hypertrophied septum is therefore available for cell isolation from the fresh tissue.
A method for the isolation of human ventricular myocytes from single, small transvenous endomyocardial biopsy specimens has been previously developed and published19. We implemented a method to isolate single septal myocytes from ventricular myocardium samples from patients undergoing cardiac surgery, including patients with HCM undergoing septal myectomy and patients undergoing valve replacement procedures. In addition to a detailed description of the isolation protocol, representative electrophysiological and Ca2+ fluorescence measurements are presented, demonstrating the viability of the isolated human ventricular myocytes and the feasibility of patch clamp and intracellular Ca2+ studies.

<table border="0" cellpadding="0" cellspacing="0" width="1059">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:495px;">Potassium phosphate monobasic (KH2PO4)</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td style="width:139px;"><a href="http://www.sigmaaldrich.com/catalog/product/sigma/p9791?lang=it&amp;region=IT">P9791&#160;</a></td>
			<td style="width:255px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Magnesium sulfate heptahydrate(MgSO4 * 7H2O)</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/m1880?lang=it&amp;region=IT">M1880&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HEPES</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/h3375?lang=it&amp;region=IT">H3375&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Adenosine</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/a9251?lang=it&amp;region=IT">A9251&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">D-(+)-Glucose</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/g8270?lang=it&amp;region=IT">G8270&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mannitol</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/m4125?lang=it&amp;region=IT">M4125&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Taurine</td>
			<td style="width:172px;">Sigma-Aldrich</td>
			<td>T0625</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium hydroxide (KOH)</td>
			<td>Sigma-Aldrich</td>
			<td>P5958</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium chloride (NaCl)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/s7653?lang=it&amp;region=IT">S7653</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium chloride (KCl)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/p9333?lang=it&amp;region=IT">P9333&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium phosphate dibasic (Na2HPO4)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/s7907?lang=it&amp;region=IT">S7907&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium bicarbonate (NaHCO3)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/s6297?lang=it&amp;region=IT">S6297&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium bicarbonate (KHCO3)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/237205?lang=it&amp;region=IT">237205</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium pyruvate</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/p2256?lang=it&amp;region=IT">P2256&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2,3-Butanedione monoxime</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/b0753?lang=it&amp;region=IT">B0753&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium hydroxide(NaOH)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/s8045?lang=it&amp;region=IT">S8045&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">L-Glutamic acid monopotassium salt monohydrate</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/fluka/49601?lang=it&amp;region=IT">49601</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pyruvic acid</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/aldrich/107360?lang=it&amp;region=IT">107360</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3-Hydroxybutyric acid</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/aldrich/166898?lang=it&amp;region=IT">166898</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Adenosine 5&#8242;-triphosphate dipotassium salt dihydrate (K2-ATP)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/a8937?lang=it&amp;region=IT">A8937</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Creatine</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/c0780?lang=it&amp;region=IT">C0780&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Succinic Acid</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/s3674?lang=it&amp;region=IT">S3674&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ethylene glycol-bis(2-aminoethylether)-N,N,N&#8242;,N&#8242;-tetraacetic acid (EGTA)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sial/e0396?lang=it&amp;region=IT">E0396&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Albumin from bovine serum</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/a0281?lang=it&amp;region=IT">A0281</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Magnesium chloride (MgCl2)</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/m8266?lang=it&amp;region=IT">M8266&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Collagenase from Clostridium histolyticum, Type V</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/c9263?lang=it&amp;region=IT">C9263&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Proteinase, Bacterial, Type XXIV</td>
			<td>Sigma-Aldrich</td>
			<td>P8038</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calcium chloride solution, ~1 M in H2O</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/21115?lang=it&amp;region=IT">21115</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calcium chloride 0.1 M solution</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/53704?lang=it&amp;region=IT">53704</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium methanesulfonate</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/aldrich/83000?lang=it&amp;region=IT">83000</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FluoForte Reagent</td>
			<td>Enzo Life Sciences</td>
			<td>ENZ-52015</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Powerload concentrate, 100X</td>
			<td>Life Technologies</td>
			<td>P10020</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Perfusion Fast-Step System</td>
			<td>Warner Instruments</td>
			<td>VC-77SP</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Amphotericin B solubilized</td>
			<td>Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/a9528?lang=it&amp;region=IT">A9528&#160;</a></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Multiclamp 700B patch-clamp amplifier</td>
			<td>Molecular Devices</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digidata 1440A</td>
			<td>Molecular Devices</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pClamp10.0&#160;</td>
			<td>Molecular Devices</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="108">
			<td height="108" style="height:108px;">Digestion Device</td>
			<td>CUSTOM</td>
			<td>CUSTOM</td>
			<td style="width:255px;">The device is custome made in our laboratory using plastic tubes, cast Sylgard and a motor; it is described in detail in Fig 1 C-D and in Fig.7. We can provide further details if requested</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silicone elastomer for the digestion device&#39;s brushes</td>
			<td>Dow Corning</td>
			<td>SYLGARD&#174; 184</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Variable speed rotating motor for the digestion device</td>
			<td>Crouzet</td>
			<td>Crouzet 178-4765&#160;</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Mold for brushes casting</td>
			<td>N.A.</td>
			<td>N.A.</td>
			<td style="width:255px;">The mold is custom made from standard PTFE 2.5 cm diameter rods</td>
		</tr>
	</tbody>
</table>

isolation and functional characterization of human ventricular cardiomyocytes from fresh surgical samples

Cardiomyocytes from diseased hearts are subjected to complex remodeling processes involving changes in cell structure, excitation contraction coupling and membrane ion currents. Those changes are likely&#160;to be responsible for the increased arrhythmogenic risk and the contractile alterations leading to systolic and diastolic dysfunction in cardiac patients. However, most information on the alterations of myocyte function in cardiac diseases has come from animal models.
Here we describe and validate a protocol to isolate viable myocytes from small surgical samples of ventricular myocardium from patients undergoing cardiac surgery operations. The protocol is described in detail. Electrophysiological and intracellular calcium measurements are reported to demonstrate the feasibility of a number of single cell measurements in human ventricular cardiomyocytes obtained with this method.
The protocol reported here can be useful for future investigations of the cellular and molecular basis of functional alterations of the human heart in the presence of different cardiac diseases. Further, this method can be used to identify novel therapeutic targets at cellular level and to test the effectiveness of new compounds on human cardiomyocytes, with direct translational value.

The method described above was employed to characterize the functional abnormalities of cardiomyocytes isolated from the interventricular septum of patients with hypertrophic cardiomyopathy (HCM) who underwent myectomy operation, as compared with non failing non hypertrophic surgical patients21. The results contained in this section are derived from that work21 and are shown here as an example of how this technique can be used to characterize the alterations of myocardial cell function in cardiac di...

Watch this Scientific Journal Video about Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples at JoVE.com

Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples

Current knowledge on the cellular basis of cardiac diseases mostly relies on studies on animal models. Here we describe and validate a novel method to obtain single viable cardiomyocytes from small surgical samples of human ventricular myocardium. Human ventricular myocytes can be used for electrophysiological studies and drug testing.

Cardiomyocytes from diseased hearts are subjected to complex remodeling processes involving changes in cell structure, excitation contraction coupling and ...

isolation-functional-characterization-human-ventricular

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JoVE Journal

Medicine

17.1K Views.  University of Florence. Current knowledge on the cellular basis of cardiac diseases mostly relies on studies on animal models. Here we describe and validate a novel method to obtain single viable cardiomyocytes from small surgical samples of human ventricular myocardium. Human ventricular myocytes can be used for electrophysiological studies and drug testing.

Video: Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples

Patient Derived Cell Culture and Isolation of CD133+ Putative Cancer Stem Cells from Melanoma

Despite improved treatments options for melanoma available today, patients with advanced malignant melanoma still have a poor prognosis for progression-free and overall survival. Therefore, translational research needs to provide further molecular evidence to improve targeted therapies for malignant melanomas. In the past, oncogenic mechanisms related to melanoma were extensively studied in established cell lines. On the way to more personalized treatment regimens based on individual genetic profiles, we propose to use patient-derived cell lines instead of generic cell lines. Together with high quality clinical data, especially on patient follow-up, these cells will be instrumental to better understand the molecular mechanisms behind melanoma progression.
Here, we report the establishment of primary melanoma cultures from dissected fresh tumor tissue. This procedure includes mincing and dissociation of the tissue into single cells, removal of contaminations with erythrocytes and fibroblasts as well as primary culture and reliable verification of the cells' melanoma origin.
Recent reports revealed that melanomas, like the majority of tumors, harbor a small subpopulation of cancer stem cells (CSCs), which seem to exclusively fuel tumor initiation and progression towards the metastatic state. One of the key markers for CSC identification and isolation in melanoma is CD133. To isolate CD133+ CSCs from primary melanoma cultures, we have modified and optimized the Magnetic-Activated Cell Sorting (MACS) procedure from Miltenyi resulting in high sorting purity and viability of CD133+ CSCs and CD133- bulk, which can be cultivated and functionally analyzed thereafter.

Patient Derived Cell Culture and Isolation of CD133+ Putative Cancer Stem Cells from Melanoma

This article describes the preparation of freshly obtained melanoma tissue into primary cell cultures, and how to remove contaminations of erythrocytes and fibroblasts from the tumor cells. Finally, we describe how CD133+ putative melanoma stem cells are sorted from the CD133- bulk using Magnetic Activated Cell Sorting (MACS).

Despite improved treatments options for melanoma available today, patients with advanced malignant melanoma still have a poor prognosis for ...

Isolation of Cancer Stem Cells From Human Prostate Cancer Samples

The cancer stem cell (CSC) model has been considerably revisited over the last two decades. During this time CSCs have been identified and directly isolated from human tissues and serially propagated in immunodeficient mice, typically through antibody labeling of subpopulations of cells and fractionation by flow cytometry. However, the unique clinical features of prostate cancer have considerably limited the study of prostate CSCs from fresh human tumor samples. We recently reported the isolation of prostate CSCs directly from human tissues by virtue of their HLA class I (HLAI)-negative phenotype. Prostate cancer cells are harvested from surgical specimens and mechanically dissociated. A cell suspension is generated and labeled with fluorescently conjugated HLAI and stromal antibodies. Subpopulations of HLAI-negative cells are finally isolated using a flow cytometer. The principal limitation of this protocol is the frequently microscopic and multifocal nature of primary cancer in prostatectomy specimens. Nonetheless, isolated live prostate CSCs are suitable for molecular characterization and functional validation by transplantation in immunodeficient mice.

The isolation of cancer stem cells (CSCs) directly from human tissues is requisite for their biological characterization. This manuscript describes a methodology for the isolation of prostate CSCs from human tissues, while also providing tips on troubleshooting difficult steps.

The cancer stem cell (CSC) model has been considerably revisited over the last two decades. During this time CSCs have been identified and directly ...

Collection, Isolation, and Flow Cytometric Analysis of Human Endocervical Samples

Despite the public health importance of mucosal pathogens (including HIV), relatively little is known about mucosal immunity, particularly at the female genital tract (FGT). Because heterosexual transmission now represents the dominant mechanism of HIV transmission, and given the continual spread of sexually transmitted infections (STIs), it is critical to understand the interplay between host and pathogen at the genital mucosa. The substantial gaps in knowledge around FGT immunity are partially due to the difficulty in successfully collecting and processing mucosal samples. In order to facilitate studies with sufficient sample size, collection techniques must be minimally invasive and efficient. To this end, a protocol for the collection of cervical cytobrush samples and subsequent isolation of cervical mononuclear cells (CMC) has been optimized. Using ex vivo flow cytometry-based immunophenotyping, it is possible to accurately and reliably quantify CMC lymphocyte/monocyte population frequencies and phenotypes. This technique can be coupled with the collection of cervical-vaginal lavage (CVL), which contains soluble immune mediators including cytokines, chemokines and anti-proteases, all of which can be used to determine the anti- or pro-inflammatory environment in the vagina.

The use of cytobrush sampling to collect lymphocytes and monocytes from the endocervix is a minimally invasive technique that provides samples for analysis of female genital tract immunity. In this protocol, we describe the collection of cytobrush samples and immune cell isolation for flow cytometry assays.

Despite the public health importance of mucosal pathogens (including HIV), relatively little is known about mucosal immunity, particularly at the female ...

Chronic Thromboembolic Pulmonary Hypertension and Assessment of Right Ventricular Function in the Piglet

An original piglet model of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) associated with chronic Right Ventricular (RV) dysfunction is described. Pulmonary Hypertension (PH) was induced in 3-week-old piglets by a progressive obstruction of the pulmonary vascular bed. A ligation of the left Pulmonary Artery (PA) was performed first through a mini-thoracotomy. Second, weekly embolizations of the right lower pulmonary lobe were done under fluoroscopic guidance with n-butyl-2-cyanoacrylate during 5 weeks. Mean Pulmonary Arterial Pressure (mPAP) measured by ritght heart catheterism, increased progressively, as well as Right Atrial pressure and Pulmonary Vascular Resistances (PVR) after 5 weeks compared to sham animals. Right Ventricular (RV) structural and functional remodeling were assessed by transthoracic echocardiography (RV diameters, RV wall thickness, RV systolic function). RV elastance and RV-pulmonary coupling were assessed by Pressure-Volume Loops (PVL) analysis with conductance method. Histologic study of the lung and the right ventricle were also performed. Molecular analyses on RV fresh tissues could be performed through repeated transcutaneous endomyocardial biopsies. Pulmonary microvascular disease in obstructed and unobstructed territories was studied from lung biopsies using molecular analyses and pathology. Furthermore, the reliability and the reproducibility was associated with a range of PH severity in animals. Most aspects of the human CTEPH disease were reproduced in this model, which allows new perspectives for the understanding of the underlying mechanisms (mitochondria, inflammation) and new therapeutic approaches (targeted, cellular or gene therapies) of the overloaded right ventricle but also pulmonary microvascular disease.

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) and Right Ventricular (RV) dysfunction were induced in piglets by progressive obstruction of the pulmonary arteries. Consequences were remarkably similar to those observed in CTEPH patients. This animal model would be a very useful tool for pathophysiology and therapeutic experiments on CTEPH and RV failure.

An original piglet model of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) associated with chronic Right Ventricular (RV) dysfunction is described. ...

Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes

Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Cardiac sarcoplasmic reticulum (SR) serves as a Ca2+ reservoir for contraction, which reuptakes intracellular Ca2+ during relaxation. The SR Ca2+ reserve available for beats is determinate for cardiac contractibility, and the removal of intracellular Ca2+ is critical for cardiac diastolic function. Under some pathophysiological conditions, such as diabetes and heart failure, impaired calcium clearance and SR Ca2+ store in cardiomyocytes may be involved in the progress of cardiac dysfunction. Here, we describe a protocol to evaluate SRCa2+ reserve and diastolic Ca2+ removal. Briefly, a single cardiomyocyte was enzymatically isolated, and the intracellular Ca2+ fluorescence indicated by Fura-2 was recorded by a calcium imaging system. To employ caffeine for inducing total SR Ca2+ release, we preset an automatic perfusion switch program by interlinking the stimulation system and the perfusion system. Then, the mono-exponential curve fitting was used for analyzing decay time constants of calcium transients and caffeine-induced calcium pulses. Accordingly, the contribution of the SR Ca2+-ATPase (SERCA) and Na+-Ca2+ exchanger (NCX) to diastolic calcium removal was evaluated.

Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Here, we describe a protocol to evaluate sarcoplasmic reticulum Ca2+ reserve and diastolic calcium removal function in cardiomyocytes by a calcium imaging system.

Intracellular calcium recycling plays a critical role in regulation of systolic and diastolic function in cardiomyocytes. Cardiac sarcoplasmic reticulum ...

Isolation and Cultivation of Adult Rat Cardiomyocytes

In an intact heart, adjacent cells influence adult cardiomyocytes. With the method of isolation and cultivation of adult cardiomyocytes, a precise investigation of the behavior of these cells under specific treatments and environments is possible. This manuscript presents a protocol for successful isolation and cultivation of adult rat ventricular cardiomyocytes (ARVC).
The rat is sacrificed by cervical dislocation under deep anesthesia. Then, the heart is extracted and the aorta is uncovered. Subsequently, perfusion on the Langendorff perfusion system with calcium depletion and collagenase treatment is performed. Afterwards, ventricular tissue gets minced, re-circulated, and filtered, followed by three centrifugation steps with gradual addition of CaCl2 until physiological calcium concentration is reached. ARVC are plated on cell culture dishes. After refreshing the cell culture medium, ARVC can be cultivated for up to six days without changing the serum-containing culture medium. Isolation of ARVC is a calcium sensitive process. Small changes in the intracellular calcium concentration cause a decrease in the quality and viability of the isolated cells.
Freshly isolated ARVC are rod shaped. Within the first days of cultivation they lose the rod-shaped morphology and form pseudopodia-like structures (spreading). During this morphological formation ARVC initially degrade their contractile elements followed by a reformation through actin stress fibers and de novo sarcomerogenesis. After one week of cultivation, most ARVC show a widespread appearance with a clearly detectable cross striation. This process is sensitive to intracellular calcium concentration, as treatment with ionomycin attenuates spreading. Key markers in this process of de- and re-differentiation are &#946;-myosin heavy chain (&#946;-MHC), oncostatin M (OSM), and swiprosin-1 (EFHD2). Recent studies have suggested that cardiac re- and de-differentiation occurring under culture conditions mimics features seen in vivo during cardiac remodeling. Therefore, isolation and cultivation of ARVC play a key role in understanding the biology of cardiomyocytes.

Here, we present a protocol for the isolation and cultivation of adult rat ventricular cardiomyocytes (ARVC). Isolated ARVC can be used for short and long-term cultivation. The isolation and cultivation of ARVC can play a key role in developing new treatment regimens for cardiac diseases.

In an intact heart, adjacent cells influence adult cardiomyocytes. With the method of isolation and cultivation of adult cardiomyocytes, a precise ...

Development and Functional Characterization of Murine Tolerogenic Dendritic Cells

The immune system operates by maintaining a tight balance between coordinating responses against foreign antigens and maintaining an unresponsive state against self-antigens as well as antigens derived from commensal organisms. The disruption of this immune homeostasis can lead to chronic inflammation and to the development of autoimmunity. Dendritic cells (DCs) are the professional antigen-presenting cells of the innate immune system involved in activating na&#239;ve T cells to initiate immune responses against foreign antigens. However, DCs can also be differentiated into TolDCs that act to maintain and promote T cell tolerance and to suppress effector cells contributing to the development of either autoimmune or chronic inflammation conditions. The recent advancement in our understanding of TolDCs suggests that DC tolerance can be achieved by modulating their differentiation conditions. This phenomenon has led to tremendous growth in developing TolDC therapies for numerous immune disorders caused due to break in immune tolerance. Successful studies in preclinical autoimmunity murine models have further validated the immunotherapeutic utility of TolDCs in the treatment of autoimmune disorders. Today, TolDCs have become a promising immunotherapeutic tool in the clinic for reinstating immune tolerance in various immune disorders by targeting pathogenic autoimmune responses while leaving protective immunity intact. Although an array of strategies has been proposed by multiple labs to induce TolDCs, there is no consistency in characterizing the cellular and functional phenotype of these cells. This protocol provides a step-by-step guide for the development of bone marrow-derived DCs in large numbers, a unique method used to differentiate them into TolDCs with a synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid-difluoro-propyl-amide (CDDO-DFPA), and the techniques used to confirm their phenotype, including analyses of essential molecular signatures of TolDCs. Finally, we show a method to assess TolDC function by testing their immunosuppressive response in vitro and in vivo in a preclinical model of multiple sclerosis.

Here, we present a protocol to develop and characterize tolerogenic dendritic cells (TolDCs) and evaluate their immunotherapeutic utility.

The immune system operates by maintaining a tight balance between coordinating responses against foreign antigens and maintaining an unresponsive state ...

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.

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+) ...

Functional Characterization of Endogenously Expressed Human RYR1 Variants

More than 700 variants in the RYR1 gene have been identified in patients with different neuromuscular disorders including malignant hyperthermia susceptibility, core myopathies and centronuclear myopathy. Because of the diverse phenotypes linked to RYR1 mutations it is fundamental to characterize their functional effects to classify variants carried by patients for future therapeutic interventions and identify non-pathogenic variants. Many laboratories have been interested in developing methods to functionally characterize RYR1 mutations expressed in patients&#39; cells. This approach has numerous advantages, including: mutations are endogenously expressed, RyR1 is not over-expressed, use of heterologous RyR1 expressing cells is avoided. However, since patients may present mutations in different genes aside RYR1, it is important to compare results from biological material from individuals harboring the same mutation, with different genetic backgrounds. The present manuscript describes methods developed to study the functional effects of endogenously expressed RYR1 variants in: (a) Epstein Barr virus immortalized human B-lymphocytes and (b) satellite cells derived from muscle biopsies and differentiated into myotubes. Changes in the intracellular calcium concentration triggered by the addition of a pharmacological RyR1 activators are then monitored. The selected cell type is loaded with a ratiometric fluorescent calcium indicator and intracellular [Ca2+] changes are monitored either at the single cell level by fluorescence microscopy or in cell populations using a spectrofluorometer. The resting [Ca2+], agonist dose response curves are then compared between cells from healthy controls and patients harboring RYR1 variants leading to insight into the functional effect of a given variant.

Here methods used to study the functional effect of RYR1 mutations endogenously expressed in Epstein Barr Virus immortalized human B-lymphocytes and muscle biopsy derived satellite cells differentiated into myotubes are described.

More than 700 variants in the RYR1 gene have been identified in patients with different neuromuscular disorders including malignant hyperthermia ...

Modifications of the Langendorff Method for Simultaneous Isolation of Atrial and Ventricular Myocytes from Adult Mice

A single cardiomyocyte is a vital tool in the cellular and subcellular level studies of cardiac biology and diseases as a fundamental unit of contraction and electrical activity. Hence, isolating viable, high-quality cardiomyocytes from the heart is the initial and most crucial experimental step. Comparing the various protocols for isolating the cardiomyocytes of adult mice, the Langendorff retrograde perfusion is the most successful and reproducible method reported in the literature, especially for isolating ventricular myocytes. However, isolating quality atrial myocytes from the perfused heart remains challenging, and few successful isolation reports are available. Solving this complicated problem is extremely important because apart from ventricular disease, atrial disease accounts for a large part of heart diseases. Therefore, further investigations on the cellular level to reveal the mechanisms are warranted. In this paper, a protocol based on the Langendorff retrograde perfusion method is introduced and some modifications in the depth of aorta cannulation and the steps that may affect the digestion process to isolate atrial and ventricular myocytes were simultaneously made. Moreover, the isolated cardiomyocytes are confirmed to be amenable to patch clamp investigation.

This protocol describes modifications of the Langendorff method including the depth of aorta cannulation for simultaneous Isolation of atrial and ventricular myocytes from adult mice.

A single cardiomyocyte is a vital tool in the cellular and subcellular level studies of cardiac biology and diseases as a fundamental unit of contraction ...