This work was supported, in part, by the US Department of Veterans Affairs Biomedical Laboratory R&#38;D Service (I01 BX003482) and by institutional funds to M.L.R.

1. Experimental preparation/plating
<ol>
	<li>Maintain CMs and ECs according to the manufacturer&#39;s instructions.
	<ol>
		<li>Thaw both cell lines when they arrive from vendors. Plate in T25 flasks after being washed with fresh media. It is recommended to purchase each cell culture media from the same vendors the cells were purchased from. The next day, refresh the cells with media and use when confluent.</li>
		<li>Maintain the cell culture incubator at 37 &#176;C with 21% O2, 5% CO...

<ol>
	<li>Hausenloy, D. 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=Ischaemic+conditioning+and+targeting+reperfusion+injury:+a+30+year+voyage+of+discovery.">Ischaemic conditioning and targeting reperfusion injury: a 30 year voyage of discovery.</a> Basic Research in Cardiology. 111 (6), 70 (2016).</li><li>Hausenloy, D. J., Yellon, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+ischemia-reperfusion+injury:+a+neglected+therapeutic+target.">Myocardial ischemia-reperfusion injury: a neglected therapeutic target.</a> The Journal of Clinical Investigation. 123 (1), 92-100 (2013).</li><li>Gottlieb, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+death+pathways+in+acute+ischemia/reperfusion+injury.">Cell death pathways in acute ischemia/reperfusion injury.</a> Journal of Cardiovascular Pharmacology and Therapeutics. 16 (3-4), 233-238 (2011).</li><li>Colliva, A., Braga, L., Giacca, M., Zacchigna, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+cell-cardiomyocyte+crosstalk+in+heart+development+and+disease.">Endothelial cell-cardiomyocyte crosstalk in heart development and disease.</a> The Journal of Physiology. 598 (14), 2923-2939 (2020).</li><li>Bogdanowicz, D. R., Lu, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studying+cell-cell+communication+in+co-culture.">Studying cell-cell communication in co-culture.</a> Biotechnology Journal. 8 (4), 395-396 (2013).</li><li>Salzman, M. M., Bartos, J. A., Yannopoulos, D., Riess, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poloxamer+188+protects+isolated+adult+mouse+cardiomyocytes+from+reoxygenation+injury.">Poloxamer 188 protects isolated adult mouse cardiomyocytes from reoxygenation injury.</a> Pharmacology Research &amp; Perspectives. 8 (6), 00639 (2020).</li><li>Kalogeris, T., Baines, C. P., Krenz, M., Korthuis, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+biology+of+ischemia/reperfusion+injury.">Cell biology of ischemia/reperfusion injury.</a> International Review of Cell and Molecular Biology. 298, 229-317 (2012).</li><li>Martindale, J. J., Metzger, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uncoupling+of+increased+cellular+oxidative+stress+and+myocardial+ischemia+reperfusion+injury+by+directed+sarcolemma+stabilization.">Uncoupling of increased cellular oxidative stress and myocardial ischemia reperfusion injury by directed sarcolemma stabilization.</a> Journal of Molecular and Cellular Cardiology. 67, 26-37 (2014).</li><li>vander Meer, A. D., Orlova, V. V., ten Dijke, P., vanden Berg, A., Mummery, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+co-cultures+of+human+endothelial+cells+and+embryonic+stem+cell-derived+pericytes+inside+a+microfluidic+device.">Three-dimensional co-cultures of human endothelial cells and embryonic stem cell-derived pericytes inside a microfluidic device.</a> Lab on a Chip. 13, 3562-3568 (2013).</li><li>Bidarra, S. 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=Phenotypic+and+proliferative+modulation+of+human+mesenchymal+stem+cells+via+crosstalk+with+endothelial+cells.">Phenotypic and proliferative modulation of human mesenchymal stem cells via crosstalk with endothelial cells.</a> Stem Cell Research. 7, 186-197 (2011).</li><li>Campbell, J. J., Davidenko, N., Caffarel, M. M., Cameron, R. E., Watson, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multifunctional+3D+co-culture+system+for+studies+of+mammary+tissue+morphogenesis+and+stem+cell+biology.">A multifunctional 3D co-culture system for studies of mammary tissue morphogenesis and stem cell biology.</a> PloS One. 6, 25661 (2011).</li><li>Mehes, E., Mones, E., Nemeth, V., Vicsek, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collective+motion+of+cells+mediates+segregation+and+pattern+formation+in+co-cultures.">Collective motion of cells mediates segregation and pattern formation in co-cultures.</a> PloS One. 7, 31711 (2012).</li><li>Miki, Y., 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+advantages+of+co-culture+over+mono+cell+culture+in+simulating+in+vivo+environment.">The advantages of co-culture over mono cell culture in simulating in vivo environment.</a> The Journal of Steroid Biochemistry and Molecular Biology. 131 (3-5), 68-75 (2012).</li><li>Moraes, C., Mehta, G., Lesher-Perez, S. C., Takayama, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organs-on-a-chip:+a+focus+on+compartmentalized+microdevices.">Organs-on-a-chip: a focus on compartmentalized microdevices.</a> Annals of Biomedical Engineering. 40 (6), 1211-1227 (2012).</li><li>Campbell, J., Davidenko, N., Caffarel, M., Cameron, R., Watson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multifunctional+3D+co-culture+system+for+studies+of+mammary+tissue+morphogenesis+and+stem+cell+biology.">A multifunctional 3D co-culture system for studies of mammary tissue morphogenesis and stem cell biology.</a> PLoS One. 6, 25661 (2011).</li><li>Wu, M. H., Huang, S. B., Lee, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+cell+culture+systems+for+drug+research.">Microfluidic cell culture systems for drug research.</a> Lab on a Chip. 10, 939-956 (2010).</li></ol>

Critical steps in the protocol 
Cell co-culture models have been used to study cellular mechanisms of cardioprotection. How to create two separate layers with a meaningful distance between them is, thus, crucial for the development of a suitable co-culture model. A challenge in studying simulated IR, i.e., HR, injury is that not only ischemia (hypoxia) itself but also reperfusion (reoxygenation) aggravates cellular dysfunction. Therefore, a realistic model needs to reflect these characteristics by, ...

Ischemic heart disease is the leading cause of death and disability worldwide1,2. However, the treatment process of reperfusion can itself cause cardiomyocyte death, known as myocardial ischemia/reperfusion (IR) injury, for which there is still no effective remedy3. Endothelial cells (ECs) have been suggested to protect cardiomyocytes (CMs) through the secretion of paracrine signals, as well as cell-to-cell interactions4.
Cell co-culture models have been used extensively to investigate the role of autocrine and/or paracrine cell-cell interactions on cell function and differentiation. Among co-culture models, mixed co-culture is the simplest, where two different types of cells are in direct contact within a single culture compartment at a desired cell ratio5. However, separate treatments between cell types and downstream analysis of a single cell type are not readily feasible given the mixed population.
Previous studies indicated that hypoxic and ischemic insults cause significant damage to the integrity of cell membrane as measured by the release of lactate dehydrogenase (LDH). This injury is worsened upon reoxygenation, mimicking reperfusion injury6,7,8. The goal of the current protocol was to test the hypotheses that the presence of ECs can dose-dependently attenuate cell membrane leakage of CMs caused by hypoxia and reoxygenation (HR) and that the protective effect of ECs can be optimized by varying the contact distance between the two cell lines. Thus, we employed three types of cell culture inserts and Mouse Primary Coronary Artery Endothelial Cells and Adult Mouse Cardiomyocytes. The inserts, branded by Corning, Merck Millipore, and Greiner Bio-One allowed us to create three different cell culture crosstalk conditions with inter-cell line distances of 0.5, 1.0, and 2.0 mm, respectively. 100,000 ECs were plated per insert in each case.
In addition, in order to determine whether the density of ECs in co-culture contributes to HR injury attenuation in this model, we studied the dose-response relationship between EC concentration and LDH release by CMs. ECs were plated at 25,000, 50,000 and 100,000 per insert, respectively, in the 2.0 mm insert.
This report provides a step-by-step approach for investigators to use this important model to their advantage.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >Adult Mouse Cardiomyocytes (CMs)</td>
			<td >Celprogen Inc</td>
			<td >11041-14</td>
			<td >Isolated from adult C57BL/6J mouse cardiac tissue</td>
		</tr>
		<tr >
			<td >Automated Cell Counter Countess II</td>
			<td>Invitrogen</td>
			<td>A27977</td>
			<td>Cell counting for calculating cell numbers</td>
		</tr>
		<tr >
			<td >Bio-Safety Cabinet</td>
			<td>Nuaire</td>
			<td>NU425400</td>
			<td>Cell culture sterile hood</td>
		</tr>
		<tr >
			<td >Cell Culture Freezing Medium</td>
			<td>Cell Biologics Inc</td>
			<td>6916</td>
			<td>Used for cell freezing for long term cell line storage</td>
		</tr>
		<tr >
			<td >Cell Culture Incubator</td>
			<td>Nuaire</td>
			<td>Nu-5500</td>
			<td>To provide normal cell living condition (21%O2, 5%CO2, 74%N2, 37&#176;C, humidified)</td>
		</tr>
		<tr >
			<td >Cell Culture Incubator Gas Tank</td>
			<td>A-L Compressed Gases</td>
			<td>UN1013</td>
			<td>Gas needed for cell culture incubator&#160;</td>
		</tr>
		<tr >
			<td >Cell Culture Inserts A (0.5 mm)</td>
			<td>Corning Inc</td>
			<td>353095</td>
			<td>Used for EC-CM co-culture</td>
		</tr>
		<tr >
			<td >Cell Culture Inserts B (1.0 mm)</td>
			<td>Millicell Millipore</td>
			<td>PIHP01250</td>
			<td>Used for EC-CM co-culture</td>
		</tr>
		<tr >
			<td >Cell Culture Inserts C (2.0 mm)</td>
			<td>Greiner Bio-One</td>
			<td>662640</td>
			<td>Used for EC-CM co-culture</td>
		</tr>
		<tr >
			<td >Centrifuge</td>
			<td>Anstel Enterprises Inc</td>
			<td>4235</td>
			<td>For cell culture plating and passaging</td>
		</tr>
		<tr >
			<td >CMs Cell Culture Flasks T25</td>
			<td>Celprogen Inc</td>
			<td>E11041-14</td>
			<td>Used for CMs regular culture, coated by manufacturer</td>
		</tr>
		<tr >
			<td >CMs Cell Culture Medium Complete</td>
			<td>Celprogen Inc</td>
			<td>M11041-14S</td>
			<td>CMs culture complete medium</td>
		</tr>
		<tr >
			<td >CMs Cell Culture Medium Complete Phenol free</td>
			<td>Celprogen Inc</td>
			<td>M11041-14PN</td>
			<td>CMs culture medium without phenol red used during LDH measurement</td>
		</tr>
		<tr >
			<td >CMs Cell Culture Plates 96 well</td>
			<td>Celprogen Inc</td>
			<td>E11041-14-96well</td>
			<td>Used for experiments of LDH measurement, coated by manufacturer</td>
		</tr>
		<tr >
			<td >CMs Hypoxia Cell Culture Medium</td>
			<td>Celprogen Inc</td>
			<td>M11041-14GFPN</td>
			<td>CMs cell culture under hypoxic condition (glucose- and serum-free)</td>
		</tr>
		<tr >
			<td >Countess cell counting chamber slides</td>
			<td>Invitrogen</td>
			<td>C10283</td>
			<td>Counting slides used for cell counter</td>
		</tr>
		<tr >
			<td >Cyquant LDH Cytotoxicity Kit</td>
			<td>Thermo Scientific&#160;</td>
			<td>C20301</td>
			<td>LDH measurement kit</td>
		</tr>
		<tr >
			<td >ECs Cell Culture Flasks T25</td>
			<td>Fisher Scientific&#160;</td>
			<td>FB012935</td>
			<td>Used for ECs regular culture</td>
		</tr>
		<tr >
			<td >ECs Cell Culture Medium Complete</td>
			<td>Cell Biologics Inc</td>
			<td>M1168</td>
			<td>ECs culture complete medium</td>
		</tr>
		<tr >
			<td >ECs Cell Culture Medium Complete Phenol free</td>
			<td>Cell Biologics Inc</td>
			<td>M1168PF</td>
			<td>ECs culture medium without phenol red used during LDH measurement</td>
		</tr>
		<tr >
			<td >ECs Cell Culture Plates 96 well</td>
			<td>Fisher Scientific (Costar)</td>
			<td>3370</td>
			<td>Used for experiments of LDH measurement</td>
		</tr>
		<tr >
			<td >ECs Culture Gelatin-Based Coating Solution</td>
			<td>Cell Biologics Inc</td>
			<td>6950</td>
			<td>Used for coating flasks and plates for ECs</td>
		</tr>
		<tr >
			<td >ECs Hypoxia Cell Culture Medium</td>
			<td>Cell Biologics Inc</td>
			<td>GPF1168</td>
			<td>ECs cell culture under hypoxic condition (glucose- and serum-free)</td>
		</tr>
		<tr >
			<td >Fetal Bovine Serum (FBS)</td>
			<td>Fisher Scientific</td>
			<td>MT35011CV</td>
			<td>FBS-HI USDA-approved for cell culture and maintenance</td>
		</tr>
		<tr >
			<td >Hypoxia Chamber</td>
			<td>StemCell Technologies</td>
			<td>27310</td>
			<td>To create a hypoxic condition with 0.01%O2 environment</td>
		</tr>
		<tr >
			<td >Hypoxia Chamber Flow Meter</td>
			<td>StemCell Technologies</td>
			<td>27311</td>
			<td>To connect with hypoxic gas tank for a consistent gas flow speed</td>
		</tr>
		<tr >
			<td >Hypoxic Gas Tank (0.01%O2 Cylinder)</td>
			<td>A-L Compressed Gases</td>
			<td>UN1956</td>
			<td>Used to flush hypoxic medium and chamber (0.01%O2/5%CO2/94.99N2)</td>
		</tr>
		<tr >
			<td >Microscope&#160;</td>
			<td>Nikon</td>
			<td>TMS</td>
			<td>To observe cell condition</td>
		</tr>
		<tr >
			<td >Mouse Primary Coronary Artery Endothelial Cells (ECs)</td>
			<td>Cell Biologics Inc</td>
			<td>C57-6093</td>
			<td>Isolated from coronary artery of C57BL/6 mice</td>
		</tr>
		<tr >
			<td >NUNC 15ML CONICL Tubes</td>
			<td>Fisher Scientific</td>
			<td>12565269</td>
			<td>For cell culture process, experiments, solution preparation etc.</td>
		</tr>
		<tr >
			<td >NUNC 50ML CONICL Tubes</td>
			<td>Fisher Scientific</td>
			<td>12565271</td>
			<td>For cell culture process, experiments, solution preparation etc.</td>
		</tr>
		<tr >
			<td >Phosphate Buffered Saline (PBS)</td>
			<td>Sigma-Aldrich</td>
			<td>D8662</td>
			<td>Used for cell washing during culture or experiments</td>
		</tr>
		<tr >
			<td >Plate Reader</td>
			<td>BioTek Instrument</td>
			<td>11120533</td>
			<td>Colorimetric or fluorometric plate reading</td>
		</tr>
		<tr >
			<td >Reaction 96 Well Palte (clear no lid)</td>
			<td>Fisher Scientific</td>
			<td>12565226</td>
			<td>Used for LDH measurement plate reading</td>
		</tr>
		<tr >
			<td >Trypsin/EDTA for CMs</td>
			<td>Celprogen Inc</td>
			<td>T1509-014</td>
			<td>1 x sterile filtered and tissue culture tested</td>
		</tr>
		<tr >
			<td >Trypsin/EDTA for ECs</td>
			<td>Cell Biologics Inc</td>
			<td>6914/0619</td>
			<td>0.25%, cell cuture-tested</td>
		</tr>
	</tbody>
</table>

development of a cell co-culture model to mimic cardiac ischemia/reperfusion in vitro

Ischemic heart disease is the leading cause of death and disability worldwide. Reperfusion causes additional injury beyond ischemia. Endothelial cells (ECs) can protect cardiomyocytes (CMs) from reperfusion injury through cell-cell interactions. Co-cultures can help investigate the role of cell-cell interactions. A mixed co-culture is the simplest approach but is limited as isolated treatments and downstream analyses of single cell types are not feasible. To investigate whether ECs can dose-dependently attenuate CM cell damage and whether this protection can be further optimized by varying the contact distance between the two cell lines, we used Mouse Primary Coronary Artery Endothelial Cells and Adult Mouse Cardiomyocytes to test three types of cell culture inserts which varied in their inter-cell layer distance at 0.5, 1.0, and 2.0 mm, respectively. In CMs-only, cellular injury as assessed by lactate dehydrogenase (LDH) release increased significantly during hypoxia and further upon reoxygenation when the distance was 2.0 mm compared to 0.5 and 1.0 mm. When ECs and CMs were in nearly direct contact (0.5 mm), there was only a mild attenuation of the reoxygenation injury of CMs following hypoxia. This attenuation was significantly increased when the spatial distance was 1.0 mm. With 2.0 mm distance, ECs attenuated CM injury during both hypoxia and hypoxia/reoxygenation, indicating that sufficient culture distancing is necessary for ECs to crosstalk with CMs, so that secreted signal molecules can circulate and fully stimulate protective pathways. Our findings suggest, for the first time, that optimizing the EC/CM co-culture spatial environment is necessary to provide a favorable in vitro model for testing the role of ECs in CM-protection against simulated ischemia/reperfusion injury. The goal of this report is to provide a step-by-step approach for investigators to use this important model to their advantage.

All three types of inserts (A, B, C) used in this experiment have the same pore size of 0.4 &#181;m. The only difference among them is the insert-to-base height, which allows distances between the two co-cultured cell layers to be 0.5, 1.0 and 2.0 mm, respectively, (Figure 3) and that they are from different vendors (for details see Table of Materials).
To establish an in vitro co-culture model with separate layers of two cell lines under...

Watch this Scientific Journal Video about Development of a Cell Co-Culture Model to Mimic Cardiac Ischemia/Reperfusion In Vitro at JoVE.com

Development of a Cell Co-Culture Model to Mimic Cardiac Ischemia/Reperfusion In Vitro

Spatial distance is a key parameter in assessing hypoxia/reoxygenation injury in a co-culture model of separate endothelial and cardiomyocyte cell layers, suggesting, for the first time, that optimizing the co-culture spatial environment is necessary to provide a favorable in vitro model for testing the role of endothelial cells in cardiomyocyte protection.

Development of a Cell Co-Culture Model to Mimic Cardiac Ischemia/Reperfusion In Vitro

Ischemic heart disease is the leading cause of death and disability worldwide. Reperfusion causes additional injury beyond ischemia. Endothelial cells ...

Our finding suggests that optimizing the endothelial cell cardiomyocyte co-culture spatial environment is necessary to provide a favorable in vitro model for testing the role of endothelial cells in cardiomyocyte protection against simulated ischemia reprofusion injury. Cell co-culture models have been used extensively to investigate the role of cell-cell interactions on cell function and differentiation. However, separate treatments between cell types and downstream analysis of a single cell type are not readily feasible in the mixed co-culture.The current study aimed to create two separate cell layers with a meaningful distance between them where one can induce hypoxia reprofusion injury and study the result and effects on a single cell type. Begin the preparation by thawing both cell lines. Plate the cells in T25 flasks after washing them with fresh media.On the next day, refresh the cells with media and use when confluent. Maintain the cell culture incubator at 37 degrees Celsius with 21%oxygen, 5%carbon dioxide, and 74%nitrogen. Keep it humidified.Estimate the cardiomyocytes cell line confluency under a light microscope. Remove the media from the flasks containing confluent cell cultures and trypsinize with three to five milliliters of trypsin-EDTA per flask. Agitate the flask gently and incubate at 37 degrees Celsius for two to five minutes.After that, assess the enzymatic progress under a light microscope. After detachment, inactivate the trypsin solution by adding the trysin or cell solution to a 50 milliliter tube containing 10 milliliters of media per T25 flask. Centrifuge the cell suspension at 120 x g for two minutes to obtain a soft cell pellet.After centrifugation, remove the supernatant and resuspend the pellet in five milliliters of a media. Next, perform cell counting and confirm cell viability. Mix and aliquot of 10 microliters of resuspended cells and 10 microliters of trypan blue dye, then count the living cells using a cell counter.Dilute the cells with fresh regular media to achieve the desired seeding densities. Take a 24-well plate pre-coat it with extracellular matrix and plate cardiomyocytes at seeding densities of 300, 000 per well onto the bottom of the plate. Maintain the cells at 37 degrees Celsius with 5%carbon dioxide overnight.After 24 hours, plate endothelial cells into inserts at an optimal plating density of 100, 000 per insert. After 24 hours of endothelial cell plating, place endothelial cell inserts inside the cardiomyocyte wells and initiate co-culture. Allow cells to co-culture for 12 to 24 hours before performing the experiments.Prepare the hypoxic media by pouring approximately 25 milliliters of media in a 50 milliliter conical tube. Air seal the top with a silicone membrane and use a sterilized pipette to punch a hole. After that, create another hole and leave approximately 2/3 of the pipettes submerged in the media.Flush the media with hypoxic gas for five minutes at a flow rate of 30 liters per minute, then discard the media of the 24-well plates or culture inserts containing attached cells. Wash them very gently with 100 microliters of 10%PBS per well add 500 microliters of the freshly prepared hypoxic media to each well of the plates or inserts. Replace the original media with fresh normal media containing glucose and serum in the normoxic control group.Place a Petri dish filled with sterile water into the hypoxia chamber to humidify the chamber. Then place the plates containing the hypoxic groups into the chamber. Flush the hypoxia chamber with hypoxic gas for five minutes at a flow of 30 liters per minute.After that, place the chamber inside an incubator at 37 degrees Celsius for 24 hours. After hypoxia, discard the old media of the plates or inserts and add 500 microliters of normal media containing glucose and serum to each wall of the plates, then store the plates inside an incubator under normal culture conditions for two hours to mimic reperfusion. Transfer the cell culture media from the 24-well plate into a 96-well plate, then take 200 microliters of media from each well of the 24-well plate and equally distributed into four wells of the 96-well plate.Measure the absorbance for LDH using a cytotoxicity assay kit in a 96-well plate and follow the manufacturer's instructions to determine the degree of cellular injury. In this study, three types of inserts were evaluated. All three inserts had the same pore size of 0.4 micrometers.The only difference among them was the insert to base height, allowing the distances between the two co-cultured cell layers to be 0.5, 1.0, and 2.0 millimeters. Using this protocol, cells were cultured under normal oxygen conditions and then split into two groups a normoxic control group and the hypoxia group. After 24 hours, both groups were refreshed with media and cultured under normal oxygen conditions for another two hours before conducting the endpoint assays.A comparison of the three types of culture inserts in assessing lactate dehydrogenase release for cardiomyocyte alone, endothelial cells alone, and co-culture of cardiomyocyte with endothelial cells is shown here under normoxic, hypoxia only, and hypoxia reoxygenation conditions. With a 0.5 millimeter distance between the cell layers, hypoxia led to a significantly increased LDH release compared to normoxia when cardiomyocytes were cultured alone. However, LDH was only increased slightly in the hypoxia reoxygenation group compared to the hypoxia only group.When endothelial cells and cardiomyocytes were co-cultured together, the increase of LDH release under the hypoxia only conditions was not attenuated. This indicates that the endothelial cells did not have any protective effect compared to the cardiomyocytes alone group under the hypoxia only conditions. However, endothelial cells exerted mild but significant protection on cardiomyocytes during HR.When the distance between the cell layers was one millimeter, the LDH release was also significantly increased in cardiomyocytes only under the hypoxia only condition.However, unlike in the 0.5 millimeter insert, the LDH increase in cardiomyocytes only was potentiated by HR over hypoxia only conditions. This increase was even more pronounced with the two millimeters insert. The concentration of endothelial cells plated in two millimeter inserts was titrated to 25, 000, 50, 000 and 100, 000 cells per insert, respectively.it was found that increasing endothelial cell intensity in the co-culture led to a dose-dependent attenuation of LDH release caused by HR.However, no such effect was seen under normoxic conditions. This co-culture methodology is not limited to endothelial cells and cardiomyocytes. These methods should aid an investigation of specific cell-cell interactions amongst varied cell lines across multiple organs of interest.

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JoVE Journal

Biology

3.4K vistas.  Vanderbilt University Medical Center. Nuestro hallazgo sugiere que la optimización del entorno espacial de cocultivo de cardiomiocitos de células endoteliales es necesaria para proporcionar un modelo in vitro favorable para probar el papel de las células endoteliales en la protección de cardiomiocitos contra la lesión por reprofusión de isquemia simulada. Los modelos de cocultivo celular se han utilizado ampliamente para investigar el papel de las interacciones célula-célula en la función y diferenciación celular. Sin e...