Reconhecemos o apoio prestado pelas oficinas e a instalação animal do Instituto de Neurofisiologia. Este trabalho foi apoiado por Walter und Marga Boll-Stiftung, Köln Fortune e Deutsche Stiftung für Herzforschung.

O manuseio de animais deve ser conforme às diretrizes do comitê local de bem-estar animal e à Diretiva 2010/63 / UE do Parlamento Europeu. 1. Prepare Soluções <ol><li> Preparar a solução de Tyrode sem Ca 2+ (composição em mM): NaCl 136, KCl 5,4, NaH2PO4 0,33, MgCl2 1, glucose 10, HEPES 5, 2,3-butanodiona monoxime (BDM) 30. Ajustar o pH para 7,4 Com NaOH a 4 ° C. </li><li> Preparar a solução de Tyrode com Ca 2+ (composição em mM): NaCl 136, KCl 5,4, NaH2PO4 0,33, MgCl2 1, glucose 10, HEPES 5, BDM 30, CaCl 2 0,9. Ajuste o pH para 7,4 com NaOH a 4 ° C. </li><li> Prepare 4% de agarose com baixo teor de fusão: Coloque 0.6 g de agarose com baixo teor de fusão em 15 mL de solução de Tyrode sem Ca 2+ . Aqueça a mistura em um forno de microondas duas vezes a 750 W por 10-15 s até que a agarose seja dissolvida. Mantenha a solução a uma temperatura constante de 37 &amp;# 176; C e mexa continuamente. </li><li> Mantenha o Meio de Eagle Modificado de Dulbecco (DMEM) sem soro a 37 ° C com borbulhante com 5% de CO 2 , 95% de O2). </li></ol> 2. Prepare o Microtome <ol><li> Ligue o microtome. </li><li> Encha a câmara externa do microtomo com gelo. </li><li> Preencha a câmara interna do microtomo com solução de Tyrode gelada sem Ca 2+ e oxigene continuamente a solução com 100% de O2. </li><li> Coloque uma lâmina de aço no suporte da lâmina do microtomo. </li></ol> 3. Isolamento do coração do mouse <ol><li> Injete 2,500 U de heparina por via subcutânea. Aguarde 15 min. </li><li> Sacrifique o animal pela luxação cervical. </li><li> Abra o tórax por esternotomia. </li><li> Dispare cuidadosamente o pericárdio usando pequenas tesouras e uma pinça # 5. </li><li> Inserir uma cânula na aorta ascendente e perfundir as artérias coronárias in situ com o gelo TyrodeSolução sem Ca 2 + até o sangue restante ser removido. </li><li> Respete suavemente o coração com uma pinça e uma tesoura e transfira o coração na solução gelada de Tyrode montada sem Ca 2+ . </li><li> Separe os átrios dos ventrículos com um bisturi ou uma tesoura. </li></ol> 4. Incorporação dos Ventrículos em 4% de Agarose com baixo ponto de fusão <ol><li> Coloque os ventrículos com o ápice voltado para cima no molde de agarose ( Figura 1 ). Coloque o pino no meio do molde na câmara ventricular esquerda. </li><li> Encha o molde com 4% de agarose de baixo teor de fusão a 37 ° C, até que o coração esteja completamente coberto. </li><li> Coloque o molde no gelo para um endurecimento mais rápido da agarose, evitando a flutuação do tecido. </li><li> Remova o bloco de agarose contendo os ventrículos do molde com um bisturi. </li><li> Gire o bloco de cabeça para baixo e cubra as câmaras ventriculares e o espaço na parte traseira do bloco de agarose, que euS deixado pelo pino da muda, com 4% de agarose de baixo teor de fusão usando uma seringa com uma agulha de 20 G. </li><li> Corte o bloco de agarose com um bisturi para conseguir um fundo plano do bloco e posição vertical do ápice cardíaco. </li></ol> 5. Cortando o tecido ventricular <ol><li> Corrija o bloco no suporte de amostra do microtome com uma gota de cola de cianoacrilato. Enfrente o ápice cardíaco para cima. </li><li> Coloque o suporte de amostra na câmara de amostra interna do microtomo, que é preenchido com Tyrode gelado sem Ca 2+ . Cubra completamente o bloco de agarose com a solução de Tyrode. </li><li> Prepare fatias de eixos curtos com uma espessura de 150-400 μm, dependendo da aplicação adicional (para gravações de eletrodos afiados de 150-200 μm), mantenha a freqüência de vibração da lâmina a 60-70 Hz e mova a lâmina para frente o mais rápido possível . </li><li> Use uma escova fina para remover cuidadosamente a agarose restante das fatias. </li><li> Gentilmente transfeR fatiga com uma pipeta Pasteur na solução de Tyrode com Ca2 + 0,9 mM arejado com 100% de O2 e armazená-los durante pelo menos 30 minutos em gelo para recuperar do processo de corte. </li><li> Depois, mantenha as fatias durante 30 min em DMEM a 37 ° C, arejado com carbógeno, para lavar o BDM antes de continuar a usar. </li></ol> 6. Preparando a Configuração do Eletrodo Sharp <ol><li> Para pré-aquecimento, ligue todos os dispositivos elétricos 30 min antes do início das gravações. </li><li> Coloque um prato de cultura de células de 3 cm na placa de aquecimento colocada no microscópio invertido. </li><li> Coloque o eletrodo de anel personalizado ( Figura 2 ) no prato e conecte os fios de aterramento do pré-amplificador e o eletrodo de estimulação. </li><li> Ligue os tubos flexíveis do sistema de perfusão ao prato. </li><li> Encha o reservatório do sistema de perfusão com DMEM, arejado com carbógeno. </li><li> Ligar a bomba de perfusão e ajustar a perfusãoA 2-3 mL / min. </li><li> Ajuste a temperatura do DMEM no prato a 37 ° C, regulando o aquecedor de fluxo e a placa de aquecimento. </li></ol> 7. Gravações de Ação Potencial <ol><li> Coloque uma fatia ventricular no prato cheio de DMEM. </li><li> Verifique a integridade estrutural e a viabilidade (com base na função contrátil) do tecido com o microscópio invertido. </li><li> Preencha um eletrodo de vidro de gravação com KCL de 3 M. </li><li> Preencha um eletrodo de estimulação com DMEM. </li><li> Coloque o eletrodo de gravação e o eletrodo de estimulação nos suportes dos eléctrodos. </li><li> Coloque o eletrodo de estimulação cuidadosamente na fatia e ligue o estimulador elétrico. Comece com uma frequência de estimulação de 1-2 Hz. </li><li> Mova o eletrodo de gravação com o micromanipulador sobre a posição de gravação pretendida. </li><li> Abaixe lentamente o eletrodo de gravação até a ponta tocar o tecido. </li><li> Aplique um curto impulso elétrico retangular através doGravação de eletrodo para penetrar a membrana celular. </li><li> Desconexe cuidadosamente o eletrodo de gravação até garantir um sinal estável. </li><li> Comece a gravar os potenciais de ação. </li></ol>

<ol>
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N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+chronotropic+effects+of+Erythrina+senegalensis+DC+(Fabaceae)+aqueous+extract+on+mouse+heart+slice+and+pluripotent+stem+cell-derived+cardiomyocytes.">In vitro chronotropic effects of Erythrina senegalensis DC (Fabaceae) aqueous extract on mouse heart slice and pluripotent stem cell-derived cardiomyocytes.</a> J Ethnopharmacol. 165, 163-172 (2015).</li><li>Wang, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+tissue+slices:+preparation,+handling,+and+successful+optical+mapping.">Cardiac tissue slices: preparation, handling, and successful optical mapping.</a> Am J Physiol Heart Circ Physiol. 308, H1112-H1125 (2015).</li><li>Bussek, 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=Tissue+slices+from+adult+mammalian+hearts+as+a+model+for+pharmacological+drug+testing.">Tissue slices from adult mammalian hearts as a model for pharmacological drug testing.</a> Cell Physiol Biochem. 24, 527-536 (2009).</li><li>Burnashev, N. 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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+blockade+of+gap+junctional+communication+by+2,3-butanedione+monoxime+in+rat+cardiac+myocytes.">Reversible blockade of gap junctional communication by 2,3-butanedione monoxime in rat cardiac myocytes.</a> Am J Physiol. 272, C875-C885 (1997).</li><li>Watanabe, 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=Inhibitory+effect+of+2,3-butanedione+monoxime+(BDM)+on+Na(+)/Ca(2+)+exchange+current+in+guinea-pig+cardiac+ventricular+myocytes.">Inhibitory effect of 2,3-butanedione monoxime (BDM) on Na(+)/Ca(2+) exchange current in guinea-pig cardiac ventricular myocytes.</a> Br J Pharmacol. 132, 1317-1325 (2001).</li><li>Fleischmann, B. 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Os autores não têm nada a declarar.

As fatias ventriculares permitem estudos eletrofisiológicos, farmacológicos e mecânicos com uma estrutura de tecido preservada in vivo e acesso direto da tecnologia de medição a todas as regiões do coração. As propriedades potenciais de ação fisiológica foram demonstradas em fatias embrionárias, neonatais e adultas 9 , 10 , 11 . A vitalidade das fatias, com exceção das camadas superficiais direta...

As fatias de tecido fino têm sido utilizadas com freqüência na ciência básica, uma vez que Yamamot e Mcllwain mostraram em 1966 que a atividade elétrica de fatias de cérebro é mantida in vitro 1 . Desde então, estudos eletrofisiológicos e farmacológicos foram realizados em fatias do cérebro 2 , fígado 3 , pulmão 4 e tecido miocárdico 5 , 6 , 7 . As primeiras gravações de patch-clamp em fatias ventriculares de corações de ratos neonatais foram descritas em 1990 8 , mas essa técnica caiu no esquecimento por algum tempo. Mais de uma década depois, nosso grupo estabeleceu um novo método para preparar as fatias de coração de embrião murino 9 , neonatal 10 e adulto 11 . Estas fatias de tecido viáveis ​​podem ser usadas para experiências agudas (fatias adultasS podem ser cultivadas por várias horas) ou experiências culturais de curto prazo (fatias embrionárias e neonatais podem ser cultivadas por alguns dias). As fatias mostram in vivo como características eletrofisiológicas e uma dispersão de excitação homogênea conforme avaliado pelo potencial de ação de eletrodo afiado e gravações de microeletrodos 11 . Devido à sua morfologia &quot;bidimensional&quot;, eles permitem o acesso direto dos eletrodos de gravação a todas as regiões do ventrículo, o que os torna uma ferramenta interessante para investigações eletrofisiológicas e levanta novas opções experimentais em comparação com os corações inteiros de perfumes de Langendorff. A resposta ao fármaco das fatias aos bloqueadores dos canais iônicos, como o verapamil (bloqueador de canal Ca 2+ ), lidocain (bloqueador de canais de Na + ), 4-aminopiridina (bloqueador de canal K + não -seletivo dependente da tensão) e linopirdina (KCNQ K + -Bloqueador de canal) 9 , 11 </suP&gt; correspondeu a efeitos conhecidos em cardiomiócitos dissociados. As medidas da força isométrica revelaram uma relação de freqüência de força positiva e sugeriram fortemente a função contrátil intacta 10 . Esses achados demonstraram que as fatias ventriculares murinas são adequadas como um modelo de tecido in vitro para estudos fisiológicos e farmacológicos. Além disso, as fatias ventriculares de corações receptores em combinação com gravações afiadas de eletrodos provaram ser uma ferramenta muito útil para caracterizar a integração elétrica e mecânica, bem como a maturação dos 12 cardiomiócitos transplantados 12 , 13 , 14 e derivados de células-tronco. Em resumo, as fatias ventriculares são um modelo de tecido multicelular valioso e bem estabelecido e devem ser consideradas complementares a cardiomiócitos dissociados e corações perfundidos por LangendorffNa pesquisa cardiovascular, com a principal vantagem de fornecer uma estrutura de tecido in vivo (em contraste com células dissociadas), bem como acesso direto de tecnologias de medição, como gravações de eletrodos afiados para todas as regiões do coração (em contraste com preparações de coração inteiro).

<table border="0" cellpadding="0" cellspacing="0" width="895">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Leica VT 1000s</td>
			<td style="width:340px;">Leica Microsystems, Wetzlar, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;">Microtome with vibrating blade.</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:248px;">Stainless Steel Blades</td>
			<td style="width:340px;">Campden Instruments, Loughborough, England</td>
			<td>7550-1-SS</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pasteur pipettes&#160;</td>
			<td>Sigma-Aldrich, St. Louise, USA</td>
			<td>Z627992&#160;</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Fine brush, e.g. size 6 (4/32&#34;)</td>
			<td style="width:340px;">VWR, International, Radnor, USA</td>
			<td>149-2125</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Preparation table</td>
			<td style="width:340px;"></td>
			<td style="width:140px;"></td>
			<td style="width:167px;">self made</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Molt for embedding ventricles in agarose</td>
			<td style="width:340px;"></td>
			<td style="width:140px;"></td>
			<td style="width:167px;">self made</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:248px;">1 ml Syringe</td>
			<td style="width:340px;">Becton, Dickinson;&#160; Franklin Lakes, USA</td>
			<td>300013</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">27Gx3/4`` Needles</td>
			<td rowspan="2" style="width:340px;">Braun, Melsungen, Germany</td>
			<td>4657705</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">20G 11/2`` Needles</td>
			<td>4657519</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Small scissor</td>
			<td style="width:340px;">WPI, Sarasota, USA</td>
			<td>501263</td>
			<td rowspan="2" style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Tweezers #5, 0.1 x 0.06 mm tip</td>
			<td style="width:340px;">WPI, Sarasota, USA</td>
			<td>500342</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Oxygen gas (medical grade O2)</td>
			<td style="width:340px;">Linde, Munich, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Carbogen gas (95 % O2, 5 % CO2)&#160;</td>
			<td style="width:340px;">Linde, Munich, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">NaCL</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">7647-14-5</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">KCL</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">746436</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:248px;">CaCl2</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">746495</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:248px;">KH2PO4</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">NIST200B&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">HEPES</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">51558</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:248px;">NaHCO3</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">S5761&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">D(+)-Glucose</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">G8270&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:248px;">MgSO4</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">M7506&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">NaOH</td>
			<td style="width:340px;">Sigma-Aldrich, St. Louise, USA</td>
			<td style="width:140px;">S8045&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Cyanoacrylate glue&#160;</td>
			<td style="width:340px;">Henkel, D&#252;sseldorf, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Low-melt Agarose&#160;</td>
			<td style="width:340px;">Roth, Karlsruhe, Germany</td>
			<td style="width:140px;">6351.2</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Heparin-sodium-25000 I.E./5mL</td>
			<td style="width:340px;">Ratiopharm, Ulm, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Dulbecco&#39;s Modified Eagle Medium&#160; (DMEM), high glucose, GlutaMAX</td>
			<td style="width:340px;">ThermoScientific, Waltham, USA</td>
			<td style="width:140px;">10566016</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">SEC-10LX Amplifier</td>
			<td style="width:340px;">npi electronic GmbH, Tamm, Germany</td>
			<td>SEC-10LX</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">EPC 9</td>
			<td style="width:340px;">HEKA Elektronik GmbH, Lambrecht, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Zeiss Axiovert 200</td>
			<td style="width:340px;">Zeiss, Oberkochen, Germany</td>
			<td style="width:140px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">&#160;Low magnification Micromanipulator</td>
			<td style="width:340px;">Narashige, Tokyo, Japan</td>
			<td style="width:140px;">Nm-3</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">High magnification, three-axis micromanipulator</td>
			<td style="width:340px;">Narashige, Tokyo, Japan</td>
			<td style="width:140px;">MHW-3</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Peristaltic perfusion pump</td>
			<td style="width:340px;">Multi Channel Systems, Reutlingen, Germany</td>
			<td style="width:140px;">PPS2</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">2-channel temperature controller</td>
			<td style="width:340px;">Multi Channel Systems, Reutlingen, Germany</td>
			<td style="width:140px;">TCO02</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:248px;">Square pulse stimulator</td>
			<td style="width:340px;">Natus Europe GmbH, Planegg, Germany</td>
			<td style="width:140px;">Grass SD9</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Glass capillaries</td>
			<td style="width:340px;">WPI, Sarasota, USA</td>
			<td style="width:140px;">1B150F-1</td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

murine short axis ventricular heart slices for electrophysiological studies

Os cardiomiócitos murinos têm sido amplamente utilizados para estudos in vitro de fisiologia cardíaca e novas estratégias terapêuticas. No entanto, as preparações multicelulares de cardiomiócitos dissociados não são representativas da estrutura complexa in vivo de cardiomiócitos, não miocitos e matriz extracelular, que influencia as propriedades mecânicas e eletrofisiológicas do coração. Aqui descrevemos uma técnica para preparar fatias ventriculares viáveis ​​de corações de mouse adultos com uma estrutura de tecido preservada in vivo e demonstrar sua adequação para gravações eletrofisiológicas. Após a excisão do coração, os ventrículos são separados dos átrios, perfundidos com solução livre de Ca2 + contendo monoxime de 2,3-butanodiona e incorporados em um bloqueio de agarose com baixo teor de fusão a 4%. O bloco é colocado em um microtomo com uma lâmina vibratória, e fatias de tecido com uma espessura de 150-400 μm são preparadas mantendo a vibração freDa lâmina a 60-70 Hz e movendo a lâmina para a frente o mais lentamente possível. A espessura das fatias depende da aplicação adicional. As fatias são armazenadas na solução de Tyrode gelada com Ca2 + 0,9 mM e monoxime de 2,3-butanodiona (BDM) durante 30 min. Depois, as fatias são transferidas para DMEM a 37 ° C durante 30 min para lavar o BDM. As fatias podem ser usadas para estudos eletrofisiológicos com eletrodos afiados ou arrays de microeletrodos, para medidas de força para analisar a função contrátil ou para investigar a interação de cardiomiócitos derivados de células estaminais transplantadas e tecido hospedeiro. Para gravações de eletrodos afiados, uma fatia é colocada em um prato de cultura de células de 3 cm na placa de aquecimento de um microscópio invertido. A fatia é estimulada com um eletrodo unipolar, e os potenciais de ação intracelular de cardiomiócitos dentro da fatia são registrados com um eletrodo de vidro afiado.

O infarto do miocárdio leva a uma perda praticamente irreversível de cardiomiócitos. A terapia de reposição celular com cardiomiócitos derivados de células estaminais para regeneração cardíaca exógena é uma abordagem terapêutica promissora. A integração e a maturação elétrica das células transplantadas são cruciais para a segurança e eficiência da terapia de reposição celular. Para avaliar a integraçã...

Watch this Scientific Journal Video about Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies at JoVE.com

Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies

Aqui, descrevemos a preparação de fatias ventriculares viáveis ​​de camundongos adultos e seu uso para gravações de potencial de ação de eletrodos afiados. Essas preparações multicelulares proporcionam uma estrutura de tecido in vivo preservada, o que os torna um modelo valioso para estudos eletrofisiológicos e farmacológicos in vitro .

Faixas de coração ventricular de eixo curto murino para estudos eletrofisiológicos

Murine cardiomyocytes have been extensively used for in vitro studies of cardiac physiology and new therapeutic strategies. However, multicellular ...

murine-short-axis-ventricular-heart-slices-for-electrophysiological

Research

JoVE Journal

Medicine

7.3K visualizações.  University of Cologne.  Aqui, descrevemos a preparação de fatias ventriculares viáveis ​​de camundongos adultos e seu uso para gravações de potencial de ação de eletrodos afiados. Essas preparações multicelulares proporcionam uma estrutura de tecido in vivo preservada, o que os torna um modelo valioso para estudos eletrofisiológicos e farmacológicos in vitro . 

Vídeo: Murine Short Axis Ventricular Heart Slices for Electrophysiological Studies

Reduction in Left Ventricular Wall Stress and Improvement in Function in Failing Hearts using Algisyl-LVR

Injection of Algisyl-LVR, a treatment under clinical development, is intended to treat patients with dilated cardiomyopathy. This treatment was recently used for the first time in patients who had symptomatic heart failure. In all patients, cardiac function of the left ventricle (LV) improved significantly, as manifested by consistent reduction of the LV volume and wall stress. Here we describe this novel treatment procedure and the methods used to quantify its effects on LV wall stress and function.
Algisyl-LVR is a biopolymer gel consisting of Na+-Alginate and Ca2+-Alginate. The treatment procedure was carried out by mixing these two components and then combining them into one syringe for intramyocardial injections. This mixture was injected at 10 to 19 locations mid-way between the base and apex of the LV free wall in patients.
Magnetic resonance imaging (MRI), together with mathematical modeling, was used to quantify the effects of this treatment in patients before treatment and at various time points during recovery. The epicardial and endocardial surfaces were first digitized from the MR images to reconstruct the LV geometry at end-systole and at end-diastole. Left ventricular cavity volumes were then measured from these reconstructed surfaces.
Mathematical models of the LV were created from these MRI-reconstructed surfaces to calculate regional myofiber stress. Each LV model was constructed so that 1) it deforms according to a previously validated stress-strain relationship of the myocardium, and 2) the predicted LV cavity volume from these models matches the corresponding MRI-measured volume at end-diastole and end-systole. Diastolic filling was simulated by loading the LV endocardial surface with a prescribed end-diastolic pressure. Systolic contraction was simulated by concurrently loading the endocardial surface with a prescribed end-systolic pressure and adding active contraction in the myofiber direction. Regional myofiber stress at end-diastole and end-systole was computed from the deformed LV based on the stress-strain relationship.

This article describes procedures for implanting a novel hydrogel in failing hearts and quantifying its effect on left ventricular wall stress and function. These procedures have been successfully applied in dogs and humans.

Redução do Ventrículo Esquerdo de parede Estresse e Melhoria na função em falta Corações usando Algisyl-LVR

Injection of  Algisyl-LVR, a treatment under clinical development, is intended to treat  patients with dilated cardiomyopathy. This treatment was recently ...

Medicina

Murine Model of Wound Healing

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. Impaired wound healing, which occurs in diabetic patients for example, can lead to severe unfavorable outcomes such as amputation. There is, therefore, an increasing impetus to develop novel agents that promote wound repair. The testing of these has been limited to large animal models such as swine, which are often impractical. Mice represent the ideal preclinical model, as they are economical and amenable to genetic manipulation, which allows for mechanistic investigation. However, wound healing in a mouse is fundamentally different to that of humans as it primarily occurs via contraction. Our murine model overcomes this by incorporating a splint around the wound. By splinting the wound, the repair process is then dependent on epithelialization, cellular proliferation and angiogenesis, which closely mirror the biological processes of human wound healing. Whilst requiring consistency and care, this murine model does not involve complicated surgical techniques and allows for the robust testing of promising agents that may, for example, promote angiogenesis or inhibit inflammation. Furthermore, each mouse acts as its own control as two wounds are prepared, enabling the application of both the test compound and the vehicle control on the same animal. In conclusion, we demonstrate a practical, easy-to-learn, and robust model of wound healing, which is comparable to that of humans.

A murine model of cutaneous wound healing that can be used to assess therapeutic compounds in physiological and pathophysiological settings.

Modelo Murino de Cicatrização

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. ...

Intramyocardial Cell Delivery: Observations in Murine Hearts

Previous studies showed that cell delivery promotes cardiac function amelioration by release of cytokines and factors that increase cardiac tissue revascularization and cell survival. In addition, further observations revealed that specific stem cells, such as cardiac stem cells, mesenchymal stem cells and cardiospheres have the ability to integrate within the surrounding myocardium by differentiating into cardiomyocytes, smooth muscle cells and endothelial cells.
Here, we present the materials and methods to reliably deliver noncontractile cells into the left ventricular wall of immunodepleted mice. The salient steps of this microsurgical procedure involve anesthesia and analgesia injection, intratracheal intubation, incision to open the chest and expose the heart and delivery of cells by a sterile 30-gauge needle and a precision microliter syringe.
Tissue processing consisting of heart harvesting, embedding, sectioning and histological staining showed that intramyocardial cell injection produced a small damage in the epicardial area, as well as in the ventricular wall. Noncontractile cells were retained into the myocardial wall of immunocompromised mice and were surrounded by a layer of fibrotic tissue, likely to protect from cardiac pressure and mechanical load.

Intramyocardial cell delivery in murine models of cardiovascular diseases, such as hypertension or myocardial infarction, is widely used to test the therapeutic potential of different cell types in regenerative studies. Therefore, a detailed description and a clear visualization of this surgical procedure will help to define the limits and advantages of cardiovascular cell therapeutic analyses in small rodents.

Entrega celular intramiocárdico: Observações em murino Corações

Previous studies showed that cell delivery promotes cardiac function amelioration by release of cytokines and factors that increase cardiac tissue ...

Murine Heterotopic Heart Transplant Technique

It is now over forty years since this technique was first reported by Corry, Wynn and Russell. Although it took some years for other labs to become proficient in and utilize this technique, it is now widely used by many laboratories around the world. A significant refinement to the original technique was developed and reported in 2001 by Niimi. Described here are the techniques that have evolved over more than a decade in the hands of three surgeons (Plenter, Grazia, Pietra) in our center. These techniques are now being passed on to a younger generation of surgeons and researchers.
Based largely on the Niimi experience, the procedures used have evolved in the fine details - details which we will endeavor to relate here in such a way that others may be able to use this very useful model. Like Niimi, we have found that a video aid to learning is a priceless resource for the beginner.

The manuscript describes the steps required to perform the heterotopic heart transplant in the mouse.

Técnica de transplante heterotópico Murino Coração

It is now over forty years since this technique was first reported by Corry, Wynn and Russell. Although it took some years for other labs to become ...

Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ventricular assist devices (VADs) for support of the left ventricle. However, certain clinical scenarios warrant biventricular mechanical support. One strategy for some patients is the excision of both ventricles and the implantation of two VAD pumps as a total artificial heart (TAH). This has recently been made possible by the improvements in device design and the small profile of centrifugal devices. This TAH approach remains experimental with many important challenges such as the device settings to balance the right and left circulation, the orientation of the devices and the outflow graft with their influence on hemolysis and stability, and the outcome of chronic support using such an orientation. This protocol aims to provide a reproducible approach for total artificial heart replacement with two intracorporeal centrifugal VADs in a cow model.

Here, we present a protocol using two centrifugal pumps as a total artificial heart replacement.

Uso de dois dispositivos de Assistência Ventricular Intracorporeal como um coração Artificial

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ...

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and electrophysiological phenotype in the atria. That encourages us to utilize a genetically-engineered mouse model to elucidate the mechanism of AF. However, it is difficult to evaluate the electrophysiological properties in murine atria due to their small size. This protocol describes the electrophysiological evaluation of atria using an optical mapping system with a high temporal and spatial resolution in Langendorff perfused murine hearts. The optical mapping system is assembled with dual high-speed complementary metal oxide semiconductor cameras and high magnification objective lenses, to detect the fluorescence of a voltage-sensitive dye and Ca2+ indicator. To focus on the assessment of murine atria, optical mapping is performed with an area of 2 mm &#215; 2 mm or 10 mm x 10 mm, with a 100 &#215; 100 resolution (20 &#181;m/pixel or 100 &#181;m/pixel) and sampling rate of up to 10 kHz (0.1 ms) at maximum. A 1-French size quadripolar electrode pacing catheter is placed into the right atrium through the superior vena cava avoiding any mechanical damage to the atrium, and pacing stimulation is delivered through the catheter. An electrophysiological study is performed with programmed stimulation including constant pacing, burst pacing, and up to triple extrastimuli pacing. Under a spontaneous or pacing rhythm, the optical mapping recorded the action potential duration, activation map, conduction velocity, and Ca2+ transient individually in the right and left atria. In addition, the programmed stimulation also determines the inducibility of atrial tachyarrhythmias. Precise activation mapping is performed to identify the propagation of the excitation in the atrium during an induced atrial tachyarrhythmia. Optical mapping with a specialized setting enables a thorough electrophysiological evaluation of the atrium in murine pathological models.

This protocol describes the electrophysiological evaluation of murine atria utilizing an optical mapping system with a high temporal and spatial resolution, including dual recordings of the membrane voltage and Ca2+ transient under programmed stimulation through a specialized electrode catheter.

Avaliação eletrofisiológica de murino átrios com mapeamento óptico de alta resolução

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and ...

Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts

Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to larger animals. Yet, larger mammals are better suited for translational research questions related to normal cardiac physiology, pathophysiology, and preclinical testing of therapeutic agents. To overcome the technical barriers associated with employing a larger animal model in cardiac research, we describe an approach to measure physiological parameters in an isolated, Langendorff-perfused piglet heart. This approach combines two powerful experimental tools to evaluate the state of the heart: electrophysiology (EP) study and simultaneous optical mapping of transmembrane voltage and intracellular calcium using parameter sensitive dyes (RH237, Rhod2-AM). The described methodologies are well suited for translational studies investigating the cardiac conduction system, alterations in action potential morphology, calcium handling, excitation-contraction coupling and the incidence of cardiac alternans or arrhythmias.

The objective of this study was to establish a method for investigating cardiac dynamics using a translational animal model. The described experimental approach incorporates dual-emission optocardiography in conjunction with an electrophysiological study to assess electrical activity in an isolated, intact porcine heart model.

Estudos de Optocardiografia e Eletrofisiologia de Ex Vivo Langendorff-perfundido Corações

Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to ...

Murine Precision-Cut Liver Slices as an Ex Vivo Model of Liver Biology

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic fatty liver disease, metabolic liver disease, and liver cancer) requires experimental manipulation of animal models and in vitro cell cultures. Both techniques have limitations, such as the requirement of large numbers of animals for in vivo manipulation. However, in vitro cell cultures do not reproduce the structure and function of the multicellular hepatic environment. The use of precision-cut liver slices is a technique in which uniform slices of viable mouse liver are maintained in laboratory tissue culture for experimental manipulation. This technique occupies an experimental niche that exists between animal studies and in vitro cell culture methods. The presented protocol describes a straightforward and reliable method to isolate and culture precision-cut liver slices from mice. As an application of this technique, ex vivo liver slices are treated with bile acids to simulate cholestatic liver injury and ultimately assess the mechanisms of hepatic fibrogenesis.

This protocol provides a simple and reliable method for the production of viable precision-cut liver slices from mice. The ex vivo tissue samples can be maintained under laboratory tissue culture conditions for multiple days, providing a flexible model to examine liver pathobiology.

Murine Precision-Cut Liver Slices como um modelo ex vivo de biologia hepática

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic ...

Location, Dissection, and Analysis of the Murine Stellate Ganglion

The autonomic nervous system is a substantial driver of cardiac electrophysiology. Especially&#160;the role of its sympathetic branch is an ongoing matter of investigation in the pathophysiology of ventricular arrhythmias (VA). Neurons in the stellate ganglia (SG)&#160;&#8211;&#160;bilateral star-shaped structures of the sympathetic chain &#8211;&#160;are an important component of the sympathetic infrastructure. The SG are a recognized target for&#160;treatment via cardiac sympathetic denervation in patients with therapy-refractory VA. While neuronal remodeling and glial activation in the SG have been described in patients with VA, the underlying cellular and molecular processes that potentially precede the onset of arrhythmia are only insufficiently understood and should be elucidated to improve autonomic modulation. Mouse models allow us to study sympathetic neuronal remodeling, but identification of the murine SG is challenging for the inexperienced investigator. Thus, in-depth cellular and molecular biological studies of the murine SG are lacking for many common cardiac diseases. Here, we describe a basic repertoire for dissecting and studying the SG in adult mice for analyses at RNA level (RNA isolation for gene expression analyses, in situ hybridization), protein level (immunofluorescent whole mount staining), and cellular level (basic morphology, cell size measurement). We present potential solutions to overcome challenges in the preparation technique, and how to improve staining via quenching of autofluorescence. This allows for the visualization of neurons as well as glial cells via established markers in order to determine cell composition and remodeling processes. The methods presented here allow characterizing the SG to gain further information on autonomic dysfunction in mice prone to VA and can be complemented by additional techniques investigating neuronal and glial components of the autonomic nervous system in the heart.

Pathophysiological changes in the cardiac autonomic nervous system, especially in its sympathetic branch, contribute to the onset and maintenance of ventricular arrhythmias. In the present protocol, we show how to characterize murine stellate ganglia to improve the understanding of the underlying molecular and cellular processes.

Localização, Dissecção e Análise do Gânglio Murine Stellate

The autonomic nervous system is a substantial driver of cardiac electrophysiology. Especially&#160;the role of its sympathetic branch is an ongoing matter ...

Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the left ventricle by draining blood from the left atrium (LA) and returning it to the systemic arterial circulation via the femoral artery. It can provide flows ranging from 2.5-5 L/min depending on the size of the cannula. Here, we discuss the mechanism of action of LAFAB, available clinical data, indications for its use in cardiogenic shock, steps of implantation, post-procedural care, and complications associated with the use of this device and their management.
We also provide a brief video of the procedural component of device therapy, including the pre-placement preparation, percutaneous placement of the device via transseptal puncture under echocardiographic guidance and the post-operative management of device parameters.

The following article describes the stepwise procedure for placement of a device (e.g., Tandemheart) in cardiogenic shock (CS) that is a percutaneous left ventricular assist device (pLVAD) and a left atrial to femoral artery bypass (LAFAB) system that bypasses and supports the left ventricle (LV) in CS.

Uso de um dispositivo de assistência ventricular percutâneo/átrio esquerdo para o sistema de bypass da artéria femoral para choque cardiogênico

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the ...