Name: preparation of human myocardial tissue for long-term cultivation
Uploaded: 2022-06-02T14:10:00
Description: Watch this Scientific Journal Video about Preparation of Human Myocardial Tissue for Long-Term Cultivation at JoVE.com

La investigación fue financiada por las subvenciones DZHK 81Z0600207 (JH, PS y DM) y 81X2600253 (AD y TS).
Los autores desean agradecer a Claudia Fahney, Mei-Ping Wu y Matthias Semisch por su apoyo en la preparación de las configuraciones, así como por el mantenimiento regular del cultivo de tejidos.

La recolección de tejidos para los experimentos descritos aquí fue aprobada por las Juntas de Revisión Institucional de la Universidad de Munich y la Universidad Ruhr-Bochum. Los estudios se realizaron de acuerdo con las directrices de la Declaración de Helsinki. Los pacientes dieron su consentimiento informado por escrito antes de la recolección de tejidos.
1. Adquisición de tejidos
<ol><li>Obtener tejido humano de pacientes sometidos a trasplante de corazón o cirug?...

<ol>
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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=MicroRNA-365+regulates+human+cardiac+action+potential+duration.">MicroRNA-365 regulates human cardiac action potential duration.</a> Nature Communications. 13 (1), 1-15 (2022).</li><li>Moretti, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Somatic+gene+editing+ameliorates+skeletal+and+cardiac+muscle+failure+in+pig+and+human+models+of+Duchenne+muscular+dystrophy.">Somatic gene editing ameliorates skeletal and cardiac muscle failure in pig and human models of Duchenne muscular dystrophy.</a> Nature Medicine. 26 (2), 207-214 (2020).</li><li>Pitoulis, F. 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=Remodelling+of+adult+cardiac+tissue+subjected+to+physiological+and+pathological+mechanical+load+in+vitro.">Remodelling of adult cardiac tissue subjected to physiological and pathological mechanical load in vitro.</a> Cardiovascular Research. 118 (3), 814-827 (2021).</li><li>Curtis, T. M., Scholfield, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nifedipine+blocks+Ca2++store+refilling+through+a+pathway+not+involving+L-type+Ca2++channels+in+rabbit+arteriolar+smooth+muscle.">Nifedipine blocks Ca2+ store refilling through a pathway not involving L-type Ca2+ channels in rabbit arteriolar smooth muscle.</a> The Journal of Physiology. 532 (3), 609-623 (2001).</li><li>de Weille, J. R., Schweitz, H., Maes, P., Tartar, A., Lazdunski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calciseptine,+a+peptide+isolated+from+black+mamba+venom,+is+a+specific+blocker+of+the+L-type+calcium+channel.">Calciseptine, a peptide isolated from black mamba venom, is a specific blocker of the L-type calcium channel.</a> Proceedings of the National Academy of Sciences. 88 (6), 2437-2440 (1991).</li><li>Schleifer, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+molecular+modelling+study+of+the+calcium+channel+blockers+nifedipine+and+black+mamba+toxin+FS2.">Comparative molecular modelling study of the calcium channel blockers nifedipine and black mamba toxin FS2.</a> Journal of Computer-Aided Molecular Design. 11 (5), 491-501 (1997).</li><li>Thomas, G., Chung, M., Cohen, 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+dihydropyridine+(Bay-K8644)+that+enhances+calcium+currents+in+guinea+pig+and+calf+myocardial+cells.+A+new+type+of+positive+inotropic+agent.">A dihydropyridine (Bay-K8644) that enhances calcium currents in guinea pig and calf myocardial cells. A new type of positive inotropic agent.</a> Circulation Research. 56 (1), 87-96 (1985).</li><li>Pitoulis, F. G., Watson, S. A., Perbellini, F., Terracciano, C. 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+slices+come+to+age:+an+intermediate+complexity+in+vitro+cardiac+model+for+translational+research.">Myocardial slices come to age: an intermediate complexity in vitro cardiac model for translational research.</a> Cardiovascular Research. 116 (7), 1275-1287 (2020).</li><li>Watson, S. 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En el pasado, la investigación cardiovascular ha hecho grandes avances en el cultivo de cardiomiocitos. Sin embargo, el cultivo 3D de cardiomiocitos con geometría intacta aún no está bien establecido. En comparación con los protocolos anteriores aplicados para el cultivo ex vivo de tejido miocárdico, el protocolo que describimos aquí se asemeja más al entorno in vivo del tejido. Además, la aplicación de pre y postcarga permite un entorno más biomimético. Somos capaces de analizar y comprende...

En la última década, el cultivo in vitro de células miocárdicas ha realizado grandes avances, que van desde técnicas 2D y tridimensionales (3D) hasta el uso de organoides y células madre pluripotentes inducidas diferenciadas en miocitos cardíacos 1,2,3. Los cultivos de células primarias y ex vivo han demostrado ser de gran valor, especialmente para estudios genéticos y desarrollo de fármacos 4,5,6. El uso de tejidos humanos mejora el valor traslacional de los resultados. Sin embargo, el cultivo 3D a largo plazo de tejidos miocárdicos con geometría intacta no está bien establecido. La geometría intacta es una característica clave para imitar las condiciones in vivo, ya que la función cardíaca adecuada, la comunicación entre diferentes células, así como las interacciones célula-matriz son requisitos previos. El cultivo de tejido miocárdico pasó por varias fases de desarrollo. La tasa de éxito y la estabilidad del cultivo de tejido miocárdico ex vivo fueron inicialmente bastante bajas, pero los enfoques recientes han arrojado resultados prometedores 7,8,9,10,11.
Entre ellos, Fischer et al. fueron los primeros en demostrar que la viabilidad y el rendimiento contráctil del tejido miocárdico humano se pueden mantener en el cultivo de células ex vivo durante muchas semanas7. Su técnica se basaba en finas rebanadas de tejido cortadas a partir de miocardio humano explantado, que se montaban en cámaras de cultivo recientemente desarrolladas que proporcionaban condiciones biomecánicas definidas y estimulación eléctrica continua. Este método de cultivo se asemeja mucho a la función in vivo del tejido miocárdico, y ha sido reproducido por varios grupos de investigación independientes 2,12,13,14,15. Es importante destacar que las cámaras utilizadas por Fischer et al. también permitieron el registro continuo de las fuerzas desarrolladas durante un máximo de 4 meses, y por lo tanto abrieron oportunidades sin precedentes para la investigación fisiológica y farmacológica sobre el miocardio humano intacto7.
Técnicas similares fueron desarrolladas de forma independiente por otros grupos y aplicadas al miocardio humano, de ratas, porcinos yconejos 7,10,11. Pitoulis et al. desarrollaron posteriormente un método más fisiológico, que reproduce la relación fuerza-longitud normal durante un ciclo de contracción, pero es menos adecuado para el análisis de alto rendimiento16. Como tal, el enfoque general del cultivo biomimético puede considerarse como un paso más en la reducción, refinamiento y reemplazo (3R) de los experimentos con animales.
Sin embargo, la explotación de este potencial requiere procedimientos estandarizados, análisis de alto contenido y un alto nivel de rendimiento. Presentamos una técnica que combina el corte automatizado de miocardio humano vivo con el mantenimiento in vitro en un sistema de cultivo biomimético que ha llegado a estar disponible comercialmente (ver Tabla de Materiales). Con el enfoque propuesto, el número de rebanadas individuales que se pueden generar a partir de una sola muestra transmural de miocardio solo está limitado por el tiempo de procesamiento. Una muestra de tamaño y calidad suficientes (3 cm x 3 cm) a menudo produce 20-40 rebanadas de tejido que se cortan convenientemente con un vibratomo automatizado. Estas rodajas se pueden colocar en cámaras de cultivo pertenecientes al sistema. Las cámaras permiten la estimulación eléctrica, cuyos parámetros se pueden modular (es decir, la duración del pulso, la polaridad, la velocidad y la corriente), así como el ajuste de la precarga y la poscarga, utilizando cables de resorte dentro de las cámaras. La contracción de cada rebanada se registra a partir del movimiento de un pequeño imán unido a un cable de resorte y se muestra como un gráfico interpretable. Los datos se pueden registrar en todo momento y analizar utilizando software disponible gratuitamente. Además de la estimulación basal constante, se pueden realizar protocolos programados para evaluar funcionalmente su período refractario, umbral de estimulación, potenciación posterior a la pausa y relación fuerza-frecuencia.
Este cultivo biomimético a largo plazo de múltiples rebanadas de miocardio de un corazón individual allana el camino para futuras investigaciones ex vivo en tejidos humanos y animales, y facilita la detección de efectos farmacológicos terapéuticos y cardiotóxicos en medicina cardiovascular. Ya se ha aplicado a diversos enfoques experimentales 2,12,13,15. Aquí, damos una descripción detallada paso a paso de la preparación del tejido humano y proporcionamos soluciones para los problemas de cultivo que se encuentran con frecuencia.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Chemicals</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose Low melting point</td>
			<td>Roth</td>
			<td>6351.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Bay-K8644</td>
			<td>Cayman Chemical</td>
			<td>19988</td>
			<td></td>
		</tr>
		<tr>
			<td>BDM (2,3-Butanedione monoxime)</td>
			<td>Sigma</td>
			<td>B0753-1kg</td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2*H2O</td>
			<td>Merck</td>
			<td>2382.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Calciseptine</td>
			<td>Alomone Labs</td>
			<td>SPC-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose*H2O</td>
			<td>AppliChem</td>
			<td>A3730.0500</td>
			<td></td>
		</tr>
		<tr>
			<td>H2O</td>
			<td>BBraun</td>
			<td>3703452</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>AppliChem</td>
			<td>A1069.0500</td>
			<td></td>
		</tr>
		<tr>
			<td>Histoacryl</td>
			<td>BBraun</td>
			<td>1050052</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol 100%</td>
			<td>SAV LP GmbH</td>
			<td>UN1219</td>
			<td></td>
		</tr>
		<tr>
			<td>ITS-X-supplement</td>
			<td>Gibco</td>
			<td>5150056</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Merck</td>
			<td>1.04933.0500</td>
			<td></td>
		</tr>
		<tr>
			<td>Medium 199</td>
			<td>Gibco</td>
			<td>31150-022</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2*6H2O</td>
			<td>AppliChem</td>
			<td>A1036.0500</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma</td>
			<td>S5886-1KG</td>
			<td></td>
		</tr>
		<tr>
			<td>NaH2PO4*H2O</td>
			<td>Merck</td>
			<td>1.06346.0500</td>
			<td></td>
		</tr>
		<tr>
			<td>Nifedipine</td>
			<td>Sigma</td>
			<td>N7634-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin / streptomycin x100</td>
			<td>Sigma</td>
			<td>P0781-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>&#946;-Mercaptoethanol</td>
			<td>AppliChem</td>
			<td>A1108.0100</td>
			<td></td>
		</tr>
		<tr>
			<td>Laboratory equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Flow cabinet</td>
			<td>Thermo Scientific</td>
			<td>KS15</td>
			<td></td>
		</tr>
		<tr>
			<td>Frigomix waterpump and cooling + BBraun Thermomix BM</td>
			<td>BBraun</td>
			<td></td>
			<td>In-house made combination of cooling and heating solution.</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Binder</td>
			<td>CB240</td>
			<td></td>
		</tr>
		<tr>
			<td>MyoDish bioreactor system</td>
			<td>InVitroSys GmbH</td>
			<td>MyoDish 1</td>
			<td>Myodish cultute system</td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Leica</td>
			<td>VT1200s</td>
			<td></td>
		</tr>
		<tr>
			<td>Water bath 37 degrees</td>
			<td>Haake</td>
			<td>SWB25</td>
			<td></td>
		</tr>
		<tr>
			<td>Water bath 80 degrees</td>
			<td>Daglef Patz KG</td>
			<td>7070</td>
			<td></td>
		</tr>
		<tr>
			<td>Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>100 mL plastic single-use beaker</td>
			<td>Sarstedt</td>
			<td>75.562.105</td>
			<td></td>
		</tr>
		<tr>
			<td>Filtration unit, Steritop Quick Release</td>
			<td>Millipore</td>
			<td>S2GPT05RE</td>
			<td></td>
		</tr>
		<tr>
			<td>Needles 0.9 x 70 mm 20G</td>
			<td>BBraun</td>
			<td>4665791</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic triangles</td>
			<td></td>
			<td></td>
			<td>In-house made</td>
		</tr>
		<tr>
			<td>Razor Derby premium</td>
			<td>Derby Tokai</td>
			<td>B072HJCFK6</td>
			<td></td>
		</tr>
		<tr>
			<td>Razor Gillette Silver Blue</td>
			<td>Gillette</td>
			<td>7393560010170</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel disposable</td>
			<td>Feather</td>
			<td>02.001.30.020</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe 10 mL Luer tip BD Discardit</td>
			<td>BBraun</td>
			<td>309110</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Culture Dish 10 cm</td>
			<td>Falcon</td>
			<td>353003</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Culture Dish 3.5 cm</td>
			<td>Falcon</td>
			<td>353001</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubes 50 mL</td>
			<td>Falcon</td>
			<td>352070</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of human myocardial tissue for long-term cultivation

El cultivo de cardiomiocitos ha visto un gran número de desarrollos, que van desde el cultivo de células bidimensionales (2D) hasta los organoides derivados de iPSC. En 2019, se demostró una forma ex vivo de cultivar rebanadas de miocardio obtenidas de muestras de corazón humano, mientras se acercaba a la condición in vivo de contracción miocárdica. Estas muestras se originan principalmente en trasplantes de corazón o colocaciones de dispositivos de asistencia ventricular izquierda. Utilizando un vibratomo y un sistema de cultivo especialmente desarrollado, se colocan rodajas de 300 μm de espesor entre un alambre fijo y un alambre de resorte, lo que permite un cultivo estable y reproducible durante varias semanas. Durante el cultivo, las rebanadas se estimulan continuamente de acuerdo con los entornos individuales. Las contracciones se pueden mostrar y registrar en tiempo real, y los agentes farmacológicos se pueden aplicar fácilmente. Los protocolos de estimulación definidos por el usuario se pueden programar y realizar para evaluar parámetros vitales de contracción como la potenciación posterior a la pausa, el umbral de estimulación, la relación fuerza-frecuencia y el período refractario. Además, el sistema permite un ajuste variable de pre y postcarga para un cultivo más fisiológico.
Aquí, presentamos una guía paso a paso sobre cómo generar un cultivo exitoso a largo plazo de cortes de miocardio del ventrículo izquierdo humano, utilizando una solución de cultivo biomimético comercial.

La contracción de las rodajas de miocardio se mostró en la pantalla de la computadora después de la inserción de la cámara de cultivo en su conector correspondiente (Figura 3). La contracción de las rebanadas de miocardio humano comenzó inmediatamente después de la estimulación. Las rebanadas hipercontraídas durante 5-10 min. Esto fue visible como un aumento de las fuerzas diastólicas, causadas por una contractura tónica de fracciones de tejido dañadas. Este proceso se revirtió...

Watch this Scientific Journal Video about Preparation of Human Myocardial Tissue for Long-Term Cultivation at JoVE.com

Preparation of Human Myocardial Tissue for Long-Term Cultivation

Presentamos un protocolo para el cultivo ex vivo de tejido miocárdico ventricular humano. Permite un análisis detallado de la fuerza de contracción y la cinética, así como la aplicación de pre y postcarga para imitar más de cerca el entorno fisiológico in vivo .

Preparación del tejido miocárdico humano para el cultivo a largo plazo

Cardiomyocyte cultivation has seen a vast number of developments, ranging from two-dimensional (2D) cell cultivation to iPSC derived organoids. In 2019, ...

Usando este protocolo, las rodajas de tejido ventricular izquierdo humano se pueden cultivar ex vivo en una cámara biomimética. La aplicación de pre y postcargas mejora la semejanza del entorno fisiológico. Esta técnica permite el registro continuo de la contracción del tejido.Los protocolos de estimulación definidos por el usuario permiten la evaluación de parámetros vitales de contracción como la potenciación posterior a la pausa, el umbral de estimulación, la relación fuerza-frecuencia y el período refractario. El cultivo a largo plazo de rebanadas de miocardio, utilizando esta configuración, allanará el camino para futuras investigaciones ex vivo, facilitando esta detección de efectos farmacológicos terapéuticos y cardiotóxicos en medicina cardiovascular. Para comenzar, sumerja las cámaras de cultivo y los electrodos de grafito en un litro de una solución de isopropanol al 10% y agite durante la noche.Al día siguiente, transfiera las cámaras a una solución de isopropanol al 100% durante 3 minutos, luego permita que las cámaras y los electrodos de grafito se sequen al aire bajo una campana de flujo laminar. Conecte una placa de circuito a cada cámara de acuerdo con las posiciones disponibles en el balancín. Coloque dos electrodos de grafito en la placa de circuito según las instrucciones del fabricante, luego coloque una tapa de placa de Petri de 35 milímetros en la cámara para evitar infecciones.A continuación, llene la bandeja de corte hasta un 90 a 95% con tampón de corte. Transfiera la muestra de tejido a una placa de Petri de 100 milímetros llena de tampón de corte frío y coloque la placa en una placa de enfriamiento a 4 grados centígrados. Retire las trabéculas endocárdicas sosteniendo el endocardio con pinzas, luego use tijeras para cortar aproximadamente 3 milímetros de tejido endocárdico.Fije la muestra de tejido cortado, lado endocárdico hasta un parche de goma de 2 por 2 centímetros utilizando cuatro agujas de calibre 20 de 0,9 por 70 milímetros que se fijan en una posición cuadrada. Asegúrese de que el borde diagonal de cada punta de la aguja apunte hacia adentro, mejorando la fijación y previniendo daños en el miocardio. Con un bisturí, corte todo el exceso de tejido fuera de los cuatro cuadrados de la aguja.Con pinzas, coloque la muestra recortada en un trozo de tejido estéril durante 10 segundos para eliminar el exceso de tampón de corte. A continuación, retire la jeringa de agarosa del baño de agua y sumerja la muestra en agarosa. Deje que la agarosa se solidifique durante cinco minutos en una placa de enfriamiento.El lado endocárdico de la muestra debe ser visible en la agarosa. Usando pinzas, coloque el lado epicárdico de la muestra contenida en la agarosa en la parte superior del área pegada, luego presione suavemente la muestra que contiene agarosa desde la parte superior con una herramienta roma sin cortar o dañar la agarosa. Deje que el pegamento se solidifique durante 1 minuto.Ajuste la amplitud de vibración a 1 milímetro, la velocidad de corte inicial a 0,07 milímetros por segundo y el grosor de la rebanada a 300 micras. Después de conectar el sistema de cultivo a una computadora, inicie el programa de software correspondiente. Ajuste la velocidad del balancín a 60 rpm y preestablezca los parámetros de estimulación.Para las rebanadas cardíacas humanas, establezca la estimulación estándar a impulsos bifásicos con 50 miliamperios o corriente que consiste en 3 milisegundos de corriente positiva, 1 milisegundo de pausa y un pulso de 3 milisegundos de corriente invertida a una velocidad de ritmo de 30 latidos por minuto o lpm, luego verifique los indicadores de electrodos del software y verifique que los electrodos de las cámaras de cultivo funcionen correctamente. Usando pinzas, separe la agarosa del tejido. Evite tocar el tejido y manipularlo con cuidado, ya que cualquier daño al tejido reducirá la tasa de éxito del cultivo.Para unir dos triángulos de plástico a una muestra, coloque 1 microlitro de pegamento en una tapa estéril de placa de Petri. Use una pinza enganchada para recoger un triángulo de plástico en autoclave. Sumerja rápidamente el borde frontal del triángulo en el pegamento y pegue el triángulo sobre la muestra perpendicular a la alineación de los cardiomiocitos.Repita para el otro triángulo. Con un bisturí, recorte el tejido que exceda el ancho del triángulo y coloque la rebanada con los dos triángulos montados de nuevo en la bandeja de corte que contiene el tampón de corte. Retire la cámara de cultivo de llenado medio de la incubadora.Seleccione una rebanada preparada e insértela en la cámara conectando un triángulo a cada pasador. Ajuste la distancia entre los pines de montaje al tamaño de la muestra. Asegúrese de que la muestra esté sumergida en el medio.Después de colocar el plato en el balancín, disminuya la precarga girando el tornillo de ajuste en sentido contrario a las agujas del reloj hasta que la línea de base del gráfico correspondiente en la pantalla de la computadora ya no cambie, luego aumente cuidadosamente la precarga o la tensión girando el tornillo de ajuste en el sentido de las agujas del reloj. Para cámaras con alta rigidez, continúe hasta que la línea de base correspondiente en el gráfico haya aumentado de 1,000 a 1, 200 unidades correspondientes a una precarga de mililinewton. Después de preparar el medio de cultivo fresco, caliente previamente el medio en un baño de agua o incubadora de aire caliente a 37 grados Celsius durante 30 a 45 minutos.Retire el medio de la cámara, dejando aproximadamente 0.8 mililitros en la cámara, luego agregue 1.6 mililitros de medio fresco a la misma cámara, haciendo un volumen total de medio a 2.4 mililitros por cámara. Finalmente, coloque la cubierta de la cámara hacia atrás y coloque la cámara de cultivo en su posición respectiva. La lectura de la contracción de cinco rebanadas de miocardio durante una estimulación típica consistió en cuatro secciones distintas de potenciación posterior a la pausa, umbral de estimulación, relación fuerza-frecuencia y período refractario.En comparación con el control, la fuerza de contracción de las rebanadas tratadas con antagonistas del calcio, nifedipino y calciseptina, disminuyó en 10 minutos. En contraste, el agonista del canal de calcio dependiente de voltaje, Bay-K8644, aumentó la fuerza de contracción. Se evaluó la potenciación post-pausa de las lonchas control y tratadas para la liberación intracelular de calcio del retículo sarcoplásmico.El segmento de control no mostró ningún cambio. En presencia de calciseptina y nifedipino, la inhibición de los canales de calcio tipo L condujo a la potenciación de la primera contracción después de una pausa de 50 segundos, lo que refleja una mayor contribución relativa de la liberación de calcio intracelular a la contractilidad total. El efecto contrario se observó con Bay-K8644, que estimula la entrada de calcio extracelular a través de los canales de calcio de tipo L.En el análisis de la relación fuerza-frecuencia, no se observó ningún cambio en el segmento de control. El tratamiento con calciseptina no cambió la capacidad de la rebanada para seguir los estímulos tras un aumento de la frecuencia de estimulación al comparar los datos previos y posteriores al tratamiento. En comparación con la calciseptina, la nifedipina previno un aumento de la contractilidad a tasas de estimulación más altas y redujo la tasa máxima de captura a 80 lpm.Con Bay-K8644, se observó un aumento de la fuerza de contracción a frecuencias de estimulación muy bajas. Sin embargo, a frecuencias superiores a 50 lpm, la fuerza de contracción fue menor que durante la condición previa al tratamiento. El tejido extirpado debe transferirse rápidamente a cardioplejia de 4 grados.Después del corte, los triángulos de plástico deben unirse perpendicularmente a la dirección de la fibra. La precarga no debe exceder los 1500 milinewton. El cultivo biomimético de rebanadas puede ayudar a los investigadores a utilizar manipulaciones genéticas, así como terapias basadas en células para estudiar la regeneración y la reparación en el miocardio humano adulto.

preparation-of-human-myocardial-tissue-for-long-term-cultivation

Research

JoVE Journal

Medicine

Corneal Donor Tissue Preparation for Endothelial Keratoplasty

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection3-6.
Initially, cornea donor posterior lamellar dissection for DSEK was performed manually1 resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing.
Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in terms of the quality of the tissue7 or patient outcomes8,9 using eye bank precut tissue versus surgeon-prepared tissue for DSAEK surgery. For most corneal surgeons, the availability of precut DSAEK corneal tissue saves time and money10, and reduces the stress of performing the donor corneal dissection in the operating room. In part because of the ability of the eye banks to provide high quality posterior lamellar corneal in a timely manner, DSAEK has become the standard of care for surgical management of corneal endothelial disease.
The procedure that we are describing is the preparation of the posterior lamellar cornea at the eye bank for transplantation in DSAEK surgery (Figure 1).

Endothelial corneal transplantation is a surgical technique for treatment of posterior corneal diseases. Mechanical microkeratome dissection to prepare tissue results in thinner, more symmetric grafts with less endothelial cell loss and improved outcomes. Dissections can be performed at the eye bank prior to corneal transplantation surgery.

Preparación del tejido corneal donante para la queratoplastia endotelial

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full ...

Investigación

Medicina

Working with Human Tissues for Translational Cancer Research

Medical research for human benefit is greatly impeded by the necessity for human tissues and subjects. However, upon obtaining consent for human specimens, precious samples must be handled with the greatest care in order to ensure integrity of organs, tissues, and cells to the highest degree. Unfortunately, tissue processing by definition requires extraction of tissues from the host, a change which can cause great cellular stress and have major repercussions on subsequent analyses. These stresses could result in the specimen being no longer representative of the site from which it was retrieved. Therefore, a strict protocol must be adhered to while processing these specimens to ensure representativeness. The desired assay(s) must also be taken into consideration in order to ensure that an optimal technique is used for sample processing. Outlined here is a protocol for tissue retrieval, processing and various analyses which may be performed on processed tissue in order to maximize downstream production from limited tissue samples.

Translational cancer research is dependent on extraction of human tissues. Much work has gone into optimizing extraction methods for ex vivo analysis. Here, we describe tissue processing methods allowing for maximal data output from limited samples.

Trabajar con Tejidos Humanos para la Investigación del Cáncer Traslacional

Medical research for human benefit is greatly impeded by the necessity for human tissues and subjects. However, upon obtaining consent for human ...

Long-Term Catheterization of the Intestinal Lymph Trunk and Collection of Lymph in Neonatal Pigs

Catheterization of the intestinal lymph trunk in neonatal pigs is a technique allowing for the long-term collection of large quantities of intestinal (central) efferent lymph. Importantly, the collection of central lymph from the intestine enables researchers to study both the mechanisms and lipid constitutes associated with lipid metabolism, intestinal inflammation and cancer metastasis, as well as cells involved in immune function and immunosurveillance. A ventral mid-line surgical approach permits excellent surgical exposure to the cranial abdomen and relatively easy access to the intestinal lymph trunk vessel that lies near the pancreas and the right ventral segment of the portal vein underneath the visceral aspect of the right liver lobe. The vessel is meticulously dissected and released from the surrounding fascia and then dilated with sutures allowing for insertion and subsequent securing of the catheter into the vessel. The catheter is exteriorized and approximately 1 L/24 hr of lymph is collected over a 7 day period. While this technique enables the collection of large quantities of central lymph over an extended period of time, the success depends on careful surgical dissection, tissue handling and close attention to proper surgical technique. This is particularly important with surgeries in young animals as the lymph vessels can easily tear, potentially leading to surgical and experimental failure. The video demonstrates an excellent surgical technique for the collection of intestinal lymph.

We present a surgical procedure to catheterize the intestinal lymph trunk in neonatal pigs to collect large quantities of lipid metabolism components from efferent lymph.

Largo Plazo La cateterización de la linfa intestinal Tronco y colección de linfa en cerdos neonatales

Catheterization of the intestinal lymph trunk in neonatal pigs is a technique allowing for the long-term collection of large quantities of intestinal ...

Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early cardiopulmonary dysfunction is difficult to diagnose, particularly in animal models, as cardiopulmonary function is often measured invasively, requiring anesthesia. As many anesthetic agents are cardiodepressive, subtle changes in cardiovascular function may be masked. In contrast, chronic instrumentation allows for measurement of cardiopulmonary function in the awake state, so that measurements can be obtained under quiet resting conditions, without the effects of anesthesia and acute surgical trauma. Furthermore, when animals are properly trained, measurements can also be obtained during graded treadmill exercise.
Flow probes are placed around the aorta or pulmonary artery for measurement of cardiac output and around the left anterior descending coronary artery for measurement of coronary blood flow. Fluid-filled catheters are implanted in the aorta, pulmonary artery, left atrium, left ventricle and right ventricle for pressure measurement and blood sampling. In addition, a 20 G&#160;catheter is positioned in the anterior interventricular vein to allow coronary venous blood sampling.
After a week of recovery, swine are placed on a motor-driven treadmill, the catheters are connected to pressure and flow meters, and swine are subjected to a five-stage progressive exercise protocol, with each stage lasting 3 min. Hemodynamic signals are continuously recorded and blood samples are taken during the last 30 sec of each exercise stage.
The major advantage of studying chronically instrumented animals is that it allows serial assessment of cardiopulmonary function, not only at rest but also during physical stress such as exercise. Moreover, cardiopulmonary function can be assessed repeatedly during disease development and during chronic treatment, thereby increasing statistical power and hence limiting the number of animals required for a study.

Here we present a protocol to assess cardiopulmonary function in awake swine, at rest and during graded treadmill exercise. Chronic instrumentation allows for repeated hemodynamic measurements uninfluenced by cardiodepressive anesthetic agents.

La colocación quirúrgica de catéteres de larga duración cardiovascular prueba de esfuerzo en los cerdos

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early ...

Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. Indeed, research focusing on the discovery of new potential therapeutic targets using genetically altered mice requires a reliable, long-term assessment of the systemic arterial pressure variation. Currently, the gold standard for obtaining long-term measurements of blood pressure in ambulatory mice uses implantable radio-transmitters, which require&#160;artery cannulation. This technique eliminates the need for tethering, restraining, or anesthetizing the animals which introduce stress and artifacts during data sampling. However, arterial blood pressure monitoring in mice via catheterization can be rather challenging due to the small size of the arteries. Here we present a step-by-step guide to illustrate the crucial key passages for a successful subcutaneous implantation of radio-transmitters and carotid artery cannulation in mice. We also include examples of long-term blood pressure activity taken from freely moving mice after a period of post-surgery recovery. Following this procedure will allow reliable direct blood pressure recordings from multiple animals simultaneously.

The goal of this protocol is to assess systemic blood pressure in conscious freely moving mice using implantable radio-telemetry devices.

A largo plazo de medida de la presión arterial en ratones con libertad de movimientos mediante telemetría

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. ...

3D Whole-heart Myocardial Tissue Analysis

Cardiac regenerative therapies aim to protect and repair the injured heart in patients with ischemic heart disease. By injecting stem cells or other biologicals that enhance angio- or vasculogenesis into the infarct border zone (IBZ), tissue perfusion is improved, and the myocardium can be protected from further damage. For maximum therapeutic effect, it is hypothesized that the regenerative substance is best delivered to the IBZ. This requires accurate injections and has led to the development of new injection techniques. To validate these new techniques, we have designed a validation protocol based on myocardial tissue analysis. This protocol includes whole-heart myocardial tissue processing that enables detailed two-dimensional (2D) and three-dimensional (3D) analysis of the cardiac anatomy and intramyocardial injections. In a pig, myocardial infarction was created by a 90-min occlusion of the left anterior descending coronary artery. Four weeks later, a mixture of a hydrogel with superparamagnetic iron oxide particles (SPIOs) and fluorescent beads was injected in the IBZ using a minimally-invasive endocardial approach. 1 h after the injection procedure, the pig was euthanized, and the heart was excised and embedded in agarose (agar). After the solidification of the agar, magnetic resonance imaging (MRI), slicing of the heart, and fluorescence imaging were performed. After image post-processing, 3D analysis was performed to assess the IBZ targeting accuracy. This protocol provides a structured and reproducible method for the assessment of the targeting accuracy of intramyocardial injections into the IBZ. The protocol can be easily used when the processing of scar tissue and/or validation of the injection accuracy of the whole heart is desired.

This protocol describes a novel method for the 3D comparison of whole-heart myocardial tissue with MRI. This is designed for the accurate assessment of intramyocardial injections in the infarct border zone of a chronic porcine model of myocardial infarction.

El análisis del tejido de miocardio entero en 3D del corazón

Cardiac regenerative therapies aim to protect and repair the injured heart in patients with ischemic heart disease. By injecting stem cells or other ...

Improvement of a Closed Chest Porcine Myocardial Infarction Model by Standardization of Tissue and Blood Sampling Procedures

Myocardial ischemia reperfusion (I/R) injury contributes to almost half of the necrotic area after myocardial infarction. To date there is no approved drug to prevent or reduce myocardial I/R injury. The study and understanding of the pathophysiological mechanisms of myocardial I/R injury is essential to develop successful treatments. Large animal experiments are an important step in translational methods. The porcine model of acute myocardial infarction has been established and described by ourselves and others. We aimed to further improve the value of the model by focusing in detail on the sampling techniques for use in future experiments. Furthermore, we emphasize small but important steps that can affect the quality of the final results. To mimic the clinical situation of myocardial I/R injury, a percutaneous coronary intervention (PCI) catheter was inserted into the left anterior descending coronary artery (LAD) of an anesthetized pig. &#176;&#176;&#176;This model mimics acute myocardial infarction and PCI treatment in humans with the possibility of accurately determining the area at risk as well as the necrotic- and viable ischemic tissue. Here the model was used to investigate the effect of a bicyclic peptide inhibitor of FXIIa. The model can also be modified to allow longer reperfusion times to study later effects of myocardial infarction.

Here we demonstrate a protocol to standardize sampling procedures of an established porcine model of acute myocardial infarction in order to increase its translational value in the understanding of the pathophysiology of myocardial ischemia/reperfusion injury and to test novel drug candidates.

Mejora de un modelo de infarto de miocardio porcino pecho cerrado por normalización del tejido y procedimientos de muestreo de sangre

Myocardial ischemia reperfusion (I/R) injury contributes to almost half of the necrotic area after myocardial infarction. To date there is no approved ...

Analyzing Long-Term Electrocardiography Recordings to Detect Arrhythmias in Mice

Arrhythmias are common, affecting millions of patients worldwide. Current treatment strategies are associated with significant side effects and remain ineffective in many patients. To improve patient care, novel and innovative therapeutic concepts causally targeting arrhythmia mechanisms are needed. To study the complex pathophysiology of arrhythmias, suitable animal models are necessary, and mice have been proven to be ideal model species to evaluate the genetic impact on arrhythmias, to investigate fundamental molecular and cellular mechanisms, and to identify potential therapeutic targets.
Implantable telemetry devices are among the most powerful tools available to study electrophysiology in mice, allowing continuous ECG recording over a period of several months in freely moving, awake mice. However, due to the huge number of data points (&gt;1 million QRS complexes per day), analysis of telemetry data remains challenging. This article describes a step-by-step approach to analyze ECGs and to detect arrhythmias in long-term telemetry recordings using the software, Ponemah, with its analysis modules, ECG Pro and Data Insights, developed by Data Sciences International (DSI). To analyze basic ECG parameters, such as heart rate, P wave duration, PR interval, QRS interval, or QT duration, an automated attribute analysis was performed using Ponemah to identify P, Q, and T waves within individually adjusted windows around detected R waves. 
Results were then manually reviewed, allowing adjustment of individual annotations. The output from the attribute-based analysis and the pattern recognition analysis was then used by the Data Insights module to detect arrhythmias. This module allows an automatic screening for individually defined arrhythmias within the recording, followed by a manual review of suspected arrhythmia episodes. The article briefly discusses challenges in recording and detecting ECG signals, suggests strategies to improve data quality, and provides representative recordings of arrhythmias detected in mice using the approach described above.

Here we present a step-by-step protocol for a semiautomated approach to analyze murine long-term electrocardiography (ECG) data for basic ECG parameters and common arrhythmias. Data are obtained by implantable telemetry transmitters in living and awake mice and analyzed using Ponemah and its analysis modules.

Análisis de registros de electrocardiografía a largo plazo para detectar arritmias en ratones

Arrhythmias are common, affecting millions of patients worldwide. Current treatment strategies are associated with significant side effects and remain ...

Technique for Obtaining Mesenchymal Stem Cell from Adipose Tissue and Stromal Vascular Fraction Characterization in Long-Term Cryopreservation

Human mesenchymal stem cells derived from adipose tissue have become increasingly attractive as they show appropriate features and are an accessible source for regenerative clinical applications. Different protocols have been used to obtain adipose-derived stem cells. This article describes different steps of an improved time-saving protocol to obtain a more significant amount of ADSC, showing how to cryopreserve and thaw ADSC to obtain viable cells for culture expansion. One hundred milliliters of lipoaspirate were collected, using a 26 cm three-hole and 3 mm caliber syringe liposuction, from the abdominal area of nine patients who subsequently underwent elective abdominoplasty. The stem cells isolation was carried out with a series of washes with Dulbecco&#39;s Phosphate Buffered Saline (DPBS) solution supplemented with calcium and the use of collagenase. Stromal Vascular Fraction (SVF) cells were cryopreserved, and their viability was checked by immunophenotyping. The SVF cellular yield was 15.7 x 105 cells/mL, ranging between 6.1-26.2 cells/mL. Adherent SVF cells reached confluence after an average of 7.5 (&#177;4.5) days, with an average cellular yield of 12.3 (&#177; 5.7) x 105 cells/mL. The viability of thawed SVF after 8 months, 1 year, and 2 years ranged between 23.06%-72.34% with an average of 47.7% (&#177;24.64) with the lowest viability correlating with cases of two-year freezing. The use of DPBS solution supplemented with calcium and bag resting times for fat precipitation with a shorter time of collagenase digestion resulted in an increased stem cell final cellular yield. The detailed procedure for obtaining high yields of viable stem cells was more efficient regarding time and cellular yield than the techniques from previous studies. Even after a long period of cryopreservation, viable ADSC cells were found in the SVF.

The present protocol describes an improved methodology for ADSC isolation resulting in a tremendous cellular yield with time gain compared to the literature. This study also provides a straightforward method for obtaining a relatively large number of viable cells after long-term cryopreservation.

Técnica para la obtención de células madre mesenquimales a partir de tejido adiposo y caracterización de fracciones vasculares estromales en criopreservación a largo plazo

Human mesenchymal stem cells derived from adipose tissue have become increasingly attractive as they show appropriate features and are an accessible ...

Long-Term Continuous Measurement of Renal Blood Flow in Conscious Rats

The kidneys play a crucial role in maintaining the homeostasis of body fluids. The regulation of renal blood flow (RBF) is essential to the vital functions of filtration and metabolism in kidney function. Many acute studies have been carried out in anesthetized animals to measure RBF under various conditions to determine mechanisms responsible for the regulation of kidney perfusion. However, for technical reasons, it has not been possible to measure RBF continuously (24 h/day) in unrestrained unanesthetized rats over prolonged periods. These methods allow the continuous determination of RBF over many weeks while also simultaneously recording blood pressure (BP) with implanted catheters (fluid-filled or by telemetry). RBF monitoring is carried out with rats placed in a circular servo-controlled rat cage that enables the unrestrained movement of the rat throughout the study. At the same time, the tangling of cables from the flow probe and arterial catheters is prevented. Rats are first instrumented with an ultrasonic flow probe placement on the left renal artery and an arterial catheter implanted in the right femoral artery. These are routed subcutaneously to the nape of the neck, and connected to the flowmeter and pressure transducer, respectively, to measure RBF and BP. Following surgical implantation, rats are immediately placed in the cage to recover for at least one week and stabilize the ultrasonic probe recordings. Urine collection is also feasible in this system. The surgical and post-surgical procedures for continuous monitoring are demonstrated in this protocol.

The present protocol describes a long-term continuous measurement of renal blood flow in conscious rats and simultaneously recording blood pressure with implanted catheters (fluid-filled or by telemetry).