Name: histological quantification of chronic myocardial infarct in rats
Uploaded: 2016-12-11T14:00:00.000+00:00
Duration: 9 min 45 s
Description: Watch this Scientific Journal Video about Histological Quantification of Chronic Myocardial Infarct in Rats at JoVE.com

The study was supported by the Swiss National Foundation [SNF 310030-149986 to MNG], the University of Fribourg, and Fribourg Hospital.

Todos os animais receberam cuidados de acordo com a Convenção Europeia dos Animal Care. Os procedimentos cirúrgicos foram realizados em conformidade com a Lei de Protecção dos Animais Suíça depois de obter autorização do Serviço Veterinário do Estado, Fribourg, aprovado pelo Swiss Federal Veterinário, Suíça. Colheita 1. Coração NOTA: Todas as intervenções cirúrgicas foram realizadas sob anestesia isoflurano. Foram feitos esforços para diminuir o sofrimento animal. Em particular, todos os animais receberam uma injecção subcutânea de 0,1 mg / kg de buprenorfina pré-anestésica. O protocolo cirúrgico para indução de enfarte do miocárdio foi anteriormente descrito noutro local 13. <ol><li> Executar uma esternotomia sobre um animal myocardially infartada sob anestesia (animal entubado, 2,5% de isoflurano, a anestesia adequada confirmados pela pata pitada reflex). <ol><li> Abra o animal por o corte da pele e, em seguida, os músculoscom uma tesoura cirúrgica. Corte as costelas do lado esquerdo e direito, e em seguida, remover o peito. </li><li> Retirar as adesões restantes após a cirurgia anterior (LAD ligadura). Cortar a aorta e remover o coração. Colocar o tecido em KCl 1 M (em PBS), e em seguida lavar com PBS. </li></ol></li></ol> 2. Preparação do Tecido <ol><li> Colocar o coração infartado longitudinalmente em uma matriz de coração de rato acrílico. Mantê-lo a -20 ° C durante 1 h. </li><li> Cortar o coração diretamente na matriz usando uma lâmina de barbear com uma transversal. Certifique-se de cada fatia é de 2 mm de espessura. Cortar aproximadamente 5-7 diapositivos para cada coração (com base no nível de remodelação); isso é chamado de amostragem sistemática. </li><li> Neste passo, realizar a coloração com cloreto de 2,3,5-trifeniltetrazólio (TTC) é opcional (manter a orientação da base de fatias de coração-a-ápice). <ol><li> Incubar em 1% de TTC em PBS durante 50 min a 37 ° C. Incubar-lo em 4% de paraformaldeído (PFA) durante 20 min a 1 h. Coloque as seções between duas placas de vidro com espaçadores de 2 mm e tirar fotos com um microscópio estereológica acoplado com uma câmera de 15X de ampliação. CUIDADO! O paraformaldeído é tóxico. </li></ol></li><li> Deslize congelamento (1 opção st) <ol><li> Colocar cada lâmina em um molde de plástico (10 x 10 x 5 mm) com meio para cryotomy (temperatura de corte óptima, outubro) de montagem, manter a orientação (colocar o lado do vértice orientado da secção para baixo na parte inferior do molde). Congelar os blocos com vapores de 2-metilbutano em atmosfera de azoto líquido de arrefecimento para 10 - 15 min. Finalmente, armazenar o tecido a -80 ° C. </li></ol></li><li> Parafinização (2 opção nd) <ol><li> Colocar cada lâmina na incorporação de cassetes (manter a orientação, colocando o lado orientado para o vértice da secção para baixo na parte inferior da cassete) e, em seguida, em PFA a 4% durante 24 h. Coloque-o em uma noite máquina de processador de tecidos. <ol><li> Incubar-lo em etanol a 70% durante 2 h. Incubar em que etanol 95% durante 2 h. Incubar-lo em etanol a 100% durante 3 h. Incubar-lo em xilol durante 4 h. Incubar-lo em parafina (derretida a 60 ° C num forno), durante 5 h. Finalmente, fazer blocos, incorporando cada slide coração em parafina. </li></ol></li></ol></li></ol> 3. Masson-Goldner tricromo <ol><li> Fazer secções de tecido a partir de blocos de parafina com um micrótomo manual (espessura: 5 ^ M) ou a partir de blocos PTU com um criostato ajustado para -18 ° C (espessura: 7 mm). </li><li> Manchar um slide de cada peça do coração para cada rato (3 - 4 secções transversais por slide) com Masson-Goldner tricromo (ver anexo). NOTA: Iniciar a partir deste passo para as seções de parafina. <ol><li> Derreter as lâminas a 60 ° C num forno. De acordo com um exaustor, eles Desparafinar duas vezes em xilol durante 10 minutos cada. Rehidratar-los em 100% de etanol, 95% de etanol, 70% de etanol, e água destilada, durante 3 minutos cada. NOTA: Iniciar a partir deste passo para o criocortes. </li><li> Corrigi-los em Bouin solução durante a noite. Em seguida, lave-os em água corrente por 10 - 15 min. Lave-os em água destilada. Incubar-los em hematoxilina de Mayer por 3 min. </li><li> Retirar as lâminas e deixá-los em água destilada durante 5 minutos. Em seguida, incubam-los em ácido fucsina-Ponceau durante 5 min. Lave-os em ácido acético a 1% durante 1 min. </li><li> Em seguida, incubam-los em ácido fosfomolíbdico Orange G durante 1 min. Lave-os em ácido acético a 1% durante 1 min, incubar-las à luz corante verde durante 10 minutos, e lavá-los em ácido acético a 1% durante 1 min. </li><li> Desidratar-os em 70% de etanol (30 seg), 95% de etanol (30 seg), e etanol a 100% (5 min). Coloque uma gota de um meio de montagem resinoso nas secções de tecido, cobri-los com lamelas, e deixe-os secar. </li></ol></li></ol> Análise Tamanho 4. Infarto <ol><li> Adquirir uma imagem de cada slide em uma lupa estereoscópica (15X de ampliação) acoplado com uma câmera. Fotografar uma régua com a mesma configuraçãos. </li><li> Use software de análise de imagem para medir a espessura da cicatriz no meio do enfarte, a espessura do septo, área da cavidade do ventrículo esquerdo (VE), a área de enfarte e área de tecido do LV utilizando. <ol><li> Definir a escala com a imagem régua (Figura 1A). <ol><li> Clique em Medidas, em seguida, selecione Definir Fator de Conversão. Desenhar uma linha na barra de calibração. Botão direito do mouse sobre a imagem e clique sobre a calibração End. Observe o valor bar, e, em seguida, clique em OK. </li></ol></li><li> Escolha do LV a partir da imagem do coração coradas (Figura 1B). Use a ferramenta segmento múltipla. Selecione o ponto-a-ponto LV, e clique depois à direita Copiar / colar em qualquer lugar. </li><li> Medir a espessura da cicatriz e do septo usando a ferramenta de medição único segmento (Figura 1C </strong&gt;). </li><li> Detectar automaticamente o LV cavidade, enfarte, e áreas LV utilizando a ferramenta de medição de área automático no modo RGB (Figura 1D). <ol><li> Clique na ferramenta. Ative Só Fronteiras e Contígua no modo RGB. Finalmente, clique dentro da área de interesse para detectá-lo. Se necessário, use ferramentas de precisão. </li></ol></li></ol></li><li> Calcular o tamanho do enfarte como a relação da área de enfarte e a área de LV. </li><li> Calcular o índice de expansão da seguinte forma: [área da cavidade LV / toda a área LV] / [espessura enfarte / espessura do septo], com toda a área de LV incluindo tanto a cavidade do VE e áreas de tecido do LV. </li><li> Finalmente, calcule uma &quot;média&quot; para cada coração como segue: [média de índice de expansão das lâminas infartados] * [Número de lâminas infartados / número total de slides]. </li></ol>

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The authors have nothing to disclose.

Passos críticos dentro do Protocolo tecido fibrótico pode ser avaliada com precisão em um modelo de rato MI crónica utilizando amostragem sistemática do coração e imagem colhida análises dos cortes histológicos tricromáticas-manchado obtidos a partir da base para o ápice. Dois passos são particularmente importantes para implementação do protocolo de sucesso. Em primeiro lugar, o uso de KCl para a colheita coração permite que o músculo cardíaco a ser mantido...

O infarto do miocárdio (MI) é uma das principais causas de morte e incapacidade em todo o mundo. A doença cardíaca coronária é a causa principal; MI resulta de isquemia consecutiva a eventos coronarianos, como a oclusão. Quando reperfusão não é realizada dentro do primeiro 6 horas, isquemia induz necrose miocárdica irreversível. Em pacientes, o caracterização de MI conta com diferentes ferramentas de diagnóstico, incluindo sinais clínicos, eletrocardiograma, avaliação dos níveis plasmáticos de biomarcadores, ecocardiograma, imagiologia de ressonância magnética, e histológica 1. MI aguda e crónica são classificados como duas fases diferentes da lesão de acordo com a temporização da necrose do miocárdio em relação ao momento da oclusão coronária. A fase aguda, ocorrendo durante os primeiros 7 dias, está associada com a perda de cardiomiócitos, inflamação extensiva, e o recrutamento de fibroblastos. A fase sub-aguda, caracterizada por a cura do tecido cardíaco e a formação de uma cicatriz, ocorreentre 1 e 4 - 6 semanas. Expansão do infarto, afinamento da parede do ventrículo, e dilatação do ventrículo caracterizar a fase crônica. Remodelação extensa do ventrículo esquerdo resulta progressivamente de insuficiência cardíaca grave 2. MI induzida pelo permanente anterior esquerda artéria descendente (LAD) ligadura representa o modelo de roedor padrão de infarto crônico do miocárdio. Os imita ligadura coronária oclusão coronária. O tamanho do enfarte depende do local da ligadura. Caracterização de lesão isquémica do miocárdio em um modelo de roedor é classicamente realizada utilizando os níveis plasmáticos de biomarcadores, como a troponina I e T 3, ecocardiograma, ressonância magnética, e histologia 4,5. níveis de biomarcadores são correlacionados com a extensão da morte de cardiomiócitos. Ecocardiografia avalia a esquerda comprometimento da função ventricular resultante de anormalidades de movimento de parede regional. Além disso, técnicas de imagem não invasivos, como a ressonância magnética ou de alta resoluçãoecocardiografia, permitir a avaliação da redução do movimento da parede, o volume da área da cicatriz com diminuição da perfusão e miocárdio viável, eo afinamento da parede. dimensões do VE permitir a avaliação precisa do tamanho do infarto. Finalmente, a quantificação do miocárdio viável e mortos podem ser post-mortem realizados usando manchas específicas de secções histológicas de corações colhidas e permite a verificação do tamanho do enfarte (IS). Outra característica importante é a avaliação do índice de expansão do enfarte (EI) 6. A EI é associado com o infarto transmural e começa nos primeiros 3 dias. A EI é caracterizada por uma redução progressiva da espessura da parede, um aumento no tamanho da cavidade do VE, e consequentes alterações na forma do LV. A fim de avaliar a eficácia terapêutica de novos tratamentos - em particular, as estratégias baseadas em células regenerativas, matrizes, e o gene de avaliação de entrega precisas de MI em roedores é de importância primordial.Quando medido em uma única seção transversal obtida ao nível dos músculos papilares, o tamanho é pode ser tendenciosa, devido à grande variabilidade que existe no desenvolvimento do infarto seguinte ligadura LAD; o enfarte apex pode ser, em seguida, ocultado. Importante, as metodologias mais precisas para o tamanho determinado MI têm sido descritos para ratinhos ou ratos 7-9 10. No entanto, é insuficiente para quantificar com precisão remodelação LV ou reduções induzidas terapeuticamente (ou prevenções) da remodelação. Com efeito, este modo é geralmente expressa como uma percentagem do volume total do VE avaliada em secções transversais do coração. Embora este método é válido para infarto agudo do miocárdio, o afinamento da parede do LV que ocorre durante a remodelação permanece sub-avaliada 11,12. A quantificação morfométrica completa do tamanho do infarto e mudanças estruturais devem quantificar vários parâmetros, tais como comprimentos do endocárdio e epicárdio e diâmetros, bem como enfarte e áreas saudáveis. Nós descrevemos um aprox metodológicaoach para avaliar com precisão MI e remodelação em um modelo de rato crônica.

<table><tbody><tr><td>Acrylic rat heart matrix 2 mm</td><td>72-5015</td><td>Harvard Appartus</td><td></td></tr><tr><td>Inspira advanced volume controlled ventilator</td><td>Harvard Apparatus</td><td>557058</td><td></td></tr><tr><td>Catheter Insyte 14 G</td><td>BD</td><td>381267</td><td></td></tr><tr><td>O.C.T</td><td>BDHA361603E</td><td>VWR</td><td></td></tr><tr><td>TTC</td><td>T8877-10G</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Mayer hematoxylin</td><td>MHS32-1L</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Acid Fuchsin&lt;br/&gt; CI 42685</td><td>F8129-50G</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Ponceau Xylidin&lt;br/&gt; CI 16150</td><td>P2395-25G</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Orange G&lt;br/&gt; CI 16230</td><td>O3756-100G</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Light green&lt;br/&gt; CI 42095</td><td>L5382-25G</td><td>Sigma Aldrich</td><td></td></tr><tr><td>KCl</td><td>P9333-500G</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Xylol</td><td>10315083</td><td>HoneyWell</td><td></td></tr><tr><td>Ethanol absolute</td><td>10303990</td><td>HoneyWell</td><td></td></tr><tr><td>2-methylbutane</td><td>M32631-1L</td><td>Sigma Aldrich</td><td></td></tr><tr><td>Stereogical microscope</td><td>SM2800</td><td>Nikon</td><td></td></tr><tr><td>Formaldehyde</td><td>99340</td><td>Reactolab</td><td></td></tr><tr><td>Embedding cassette</td><td>K113.1</td><td>Carl Roth</td><td></td></tr><tr><td>Bersoft Image measurement Software</td><td></td><td>Bersoft.com</td><td>Licensed software</td></tr></tbody></table>

histological quantification of chronic myocardial infarct in rats

Myocardial infarction is defined as cardiomyocyte death due to prolonged ischemia; an inflammatory response and scar formation (fibrosis) follow the ischemic injury. Following the initial acute phase, chronic remodeling of the left ventricle (LV) modifies the structure and function of the heart. Permanent coronary ligation in small animals has been widely used as a reference model for a chronic model of MI. Thinning of the infarcted wall progressively develops to transmural fibrosis. Histological assessment of infarct size is commonly performed; nevertheless, a standardization of the methods for quantification is missing. Indeed, important methodological aspects, such as the number of sections analyzed and the sampling and quantification methods, are usually not described and therefore preclude comparison across investigations. Too often, quantification is performed on a single section obtained at the level of the papillary muscles. Because novel strategies aimed at reducing infarct expansion and remodeling are under investigation, there is an important need for the standardization of accurate heart sampling protocols. We describe an accurate method to quantify the infarct size using a systematic sampling of harvested rat heart and image analyses of trichromatic stained histological sections obtained from base to apex. We also provide evidence that calculating the expansion index (EI) allowed for infarct size assessment, taking into account changes of the left ventricle throughout the remodeling.

pós-LAD ligadura seis semanas, corações foram colhidas de ratos Lewis. secções de tecido de 2 mm foram obtidas a partir do vértice para a base. Um procedimento de coloração TTC foi realizada para visualizar a área de enfarte, que aparece em branco, eo miocárdio saudável, que aparece em vermelho (Figura 2). Dependendo do local de ligação da ADA, a dimensão do enfarte varia. Para grande MI, infartos transmurais foram observados a partir do vértice para a bas...

Watch this Scientific Journal Video about Histological Quantification of Chronic Myocardial Infarct in Rats at JoVE.com

Histological Quantification of Chronic Myocardial Infarct in Rats

The post-mortem assessment of myocardial infarction (MI) in rodents is based on quantification of the infarct on stained heart sections. We describe an accurate method to quantify the infarct size using systematic sampling of harvested rat hearts from base to apex and image analyses of trichrome-stained histological sections.

Quantificação histológico de miocárdio crônico infarto em ratos

Myocardial infarction is defined as cardiomyocyte death due to prolonged ischemia; an inflammatory response and scar formation (fibrosis) follow the ...

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14.5K visualizações.  University of Fribourg. The post-mortem assessment of myocardial infarction (MI) in rodents is based on quantification of the infarct on stained heart sections. We describe an accurate method to quantify the infarct size using systematic sampling of harvested rat hearts from base to apex and image analyses of trichrome-stained histological sections. 

Vídeo: Histological Quantification of Chronic Myocardial Infarct in Rats

Coronary Artery Ligation and Intramyocardial Injection in a Murine Model of Infarction

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo. With the advent of genetic modifications to the whole organism or the myocardium and an array of biological and/or synthetic materials, there is great potential for any combination of these to assuage the extent of acute ischemic injury and impede the onset of heart failure pursuant to myocardial remodeling. 
Here we present the methods and materials used to reliably perform this microsurgery and the modifications involved for temporary (with reperfusion) or permanent coronary artery occlusion studies as well as intramyocardial injections. The effects on the heart that can be seen during the procedure and at the termination of the experiment in addition to histological evaluation will verify efficacy. 
Briefly, surgical preparation involves anesthetizing the mice, removing the fur on the chest, and then disinfecting the surgical area. Intratracheal intubation is achieved by transesophageal illumination using a fiber optic light. The tubing is then connected to a ventilator. An incision made on the chest exposes the pectoral muscles which will be cut to view the ribs. For ischemia/reperfusion studies, a 1 cm piece of PE tubing placed over the heart is used to tie the ligature to so that occlusion/reperfusion can be customized. For intramyocardial injections, a Hamilton syringe with sterile 30gauge beveled needle is used. When the myocardial manipulations are complete, the rib cage, the pectoral muscles, and the skin are closed sequentially. Line block analgesia is effected by 0.25% marcaine in sterile saline which is applied to muscle layer prior to closure of the skin. The mice are given a subcutaneous injection of saline and placed in a warming chamber until they are sternally recumbent. They are then returned to the vivarium and housed under standard conditions until the time of tissue collection. At the time of sacrifice, the mice are anesthetized, the heart is arrested in diastole with KCl or BDM, rinsed with saline, and immersed in fixative. Subsequently, routine procedures for processing, embedding, sectioning, and histological staining are performed. 
Nonsurgical intubation of a mouse and the microsurgical manipulations described make this a technically challenging model to learn and achieve reproducibility. These procedures, combined with the difficulty in performing consistent manipulations of the ligature for timed occlusion(s) and reperfusion or intramyocardial injections, can also affect the survival rate so optimization and consistency are critical.

Numerous genetic manipulations and/or intramyocardial injections of genes, proteins, cells, and/or biomaterials are superimposed upon the dimension of time in studies of acute ischemia/ reperfusion injury and chronic remodeling in mice. This video illustrates the microsurgical procedures for ischemia/reperfusion, permanent coronary artery ligation, and intramyocardial injection studies.

Ligadura da artéria coronária e injeção intramiocárdica em um modelo murino de infarto

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo.  With the advent of genetic modifications to ...

Medicina

In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that MicroCT provides quantitative high-resolution three-dimensional (3D) anatomical data non-destructively and longitudinally. Most importantly, with the development of a novel preclinical iodinated contrast agent called eXIA160, functional and metabolic assessment of the heart became possible. However, prior to the advent of commercial MicroCT scanners equipped with X-ray flat-panel detector technology and easy-to-use cardio-respiratory gating, preclinical studies of cardiovascular disease (CVD) in small animals required a MicroCT technologist with advanced skills, and thus were impractical for widespread implementation. The goal of this work is to provide a practical guide to the use of the high-speed Quantum FX MicroCT system for comprehensive determination of myocardial global and regional function along with assessment of myocardial perfusion, metabolism and viability in healthy mice and in a cardiac ischemia mouse model induced by permanent occlusion of the left anterior descending coronary artery (LAD).

In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

This method outlines the use of Quantum Micro-Computed Tomography (MicroCT) to assess cardiac morphology, function, perfusion, metabolism and viability with iodinated contrast agent in mice with experimentally-induced myocardial ischemia. The technique can be applied for non-destructive high-throughput longitudinal in vivo imaging of various animal models of human heart disease.

In Vivo quantitativa Avaliação da Estrutura do miocárdio, função, perfusão e viabilidade Usando Cardiac Micro-Tomografia Computadorizada

The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that ...

Bioengenharia

Minimal Invasive Surgical Procedure of Inducing Myocardial Infarction in Mice

Myocardial infarction still remains the main cause of death in western countries, despite considerable progress in the stent development area in the last decades. For clarification of the underlying mechanisms and the development of new therapeutic strategies, the availability of valid animal models are mandatory. Since we need new insights into pathomechanisms of cardiovascular diseases under in vivo conditions to combat myocardial infarction, the validity of the animal model is a crucial aspect. However, protection of animals are highly relevant in this context. Therefore, we establish a minimally invasive and simple model of myocardial infarction in mice, which assures a high reproducibility and survival rate of animals. Thus, this models fulfils the requirements of the 3R principle (Replacement, Refinement and Reduction) for animal experiments and assure the scientific information needed for further developing of therapeutical strategies for cardiovascular diseases.

A highly reproducible model for myocardial infarction in mice with minimal invasive manipulations is described. The model can be easily performed, resulting in a high reproducibility and survival rate. Thus, the described model will reduce the number of required animals as requested by the 3R principle (Replacement, Refinement and Reduction).

Minimal procedimento cirúrgico invasivo de induzir Infarto do Miocárdio em Ratos

Myocardial infarction still remains the main cause of death in western countries, despite considerable progress in the stent development area in the last ...

Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are therefore required to confine cardiac damage, promote survival and reduce the disease burden of heart failure. Large animal experiments are an essential part in the translational process from experimental to clinical therapies. To optimize clinical translation, robust and representative outcome measures are mandatory. The present manuscript aims to address this need by describing the assessment of three clinically relevant outcome modalities in a pig acute myocardial infarction (AMI) model: infarct size in relation to area at risk (IS/AAR) staining, 3-dimensional transesophageal echocardiography (TEE) and admittance-based pressure-volume (PV) loops. Infarct size is the main determinant driving the transition from AMI to heart failure and can be quantified by IS/AAR staining. Echocardiography is a reliable and robust tool in the assessment of global and regional cardiac function in clinical cardiology. Here, a method for three-dimensional transesophageal echocardiography (3D-TEE) in pigs is provided. Extensive insight into cardiac performance can be obtained by admittance-based pressure-volume (PV) loops, including intrinsic parameters of myocardial function that are pre- and afterload independent. Combined with a clinically feasible experimental study protocol, these outcome measures provide researchers with essential information to determine whether novel therapeutic strategies could yield promising targets for future testing in clinical studies.

Reliable and accurate outcome assessment is the key for translation of preclinical therapies into clinical treatment. The current paper describes how to assess three clinically relevant primary outcome parameters of cardiac performance and damage in a pig acute myocardial infarction model.

Avaliação do resultado principal em um modelo suíno de Infarto Agudo do Miocárdio

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are ...

Murine Myocardial Infarction Model using Permanent Ligation of Left Anterior Descending Coronary Artery

Myocardial infarction (MI) and acute coronary diseases are among the most prominent causes of death in population with western lifestyle. The murine models of MI with permanent ligation of left-anterior descending (LAD) coronary artery closely mimics MI in humans. Murine models benefit from the extensive genetic engineering available nowadays. Here we propose a reproducible murine surgical model of myocardial infarction by permanent LAD coronary ligation. Our technique comprises anesthesia with ketamine/xylazine that can be rapidly reversed by administration of an antagonist, intubation without tracheotomy for mechanical-assisted ventilation, ventilation with application of extrinsic positive end-expiratory pressure (PEEP) to avoid alveolar collapse, a thoracotomy method limiting to the minimum surgical lesions made to skeletal muscles, and lung inflation without thoracentesis. This method is sparsely invasive, reproducible and reduces post-surgery mortality and complications.

Herein we describe a surgical procedure showing how to achieve permanent ligation of the left-anterior descending coronary artery in mice. This model is of high relevance to investigate the pathophysiology of myocardial infarction and the concomitant biological processes.

Modelo de infarto do miocárdio murino usando ligadura permanente da artéria coronária descendente anterior esquerda

Myocardial infarction (MI) and acute coronary diseases are among the most prominent causes of death in population with western lifestyle. The murine ...

A New Model of Heart Failure Post-Myocardial Infarction in the Rat

Ligation of the left anterior descending (LAD) coronary artery has been widely used to establish the rat model of heart failure (HF) post myocardial infarction (MI). However, the disadvantages of this model include high mortality rate after ligation and larger variations both in the infarct size and the degree of impaired cardiac function. In addition, a ventilator or exteriorization of the heart is indispensable for the previous models, which complicates the procedure during the ligation. In this study, we developed a reliable and reproducible model without the ventilator or exteriorization of the heart by ligating the LAD coronary artery. Four weeks after the procedure, we found that the serum concentrations of CK-MB, NT-proBNP, and Renin, which were used to assist diagnoses of MI and HF, were significantly higher in the MI group compared to the sham group. In contrast, the value of left ventricle ejection fraction (LVEF) in the MI group was obviously less than in the sham group. Furthermore, the infarct size and cardiac fibrosis area were individually confirmed and quantitatively analyzed by TTC staining and Masson's trichrome staining. Smaller variations were found in either infarct size or fibrosis area in the MI group, which helped to develop a reliable and reproducible model of HF post-MI. This new model of HF post-MI in the rat is vital for studying the potential mechanisms of MI and HF. This new method can be used to develop the new drug for treatment of MI and HF in rats by using pharmacological strategies.

We successfully developed a reliable and reproducible model of heart failure post-myocardial infarction in the rat without ventilation or exteriorization of the heart. This simplifies the procedure and benefits the further studies about the potential mechanisms behind the heart failure.

Ligation of the left anterior descending (LAD) coronary artery has been widely used to establish the rat model of heart failure (HF) post myocardial ...

An Intact Pericardium Ischemic Rodent Model

This protocol has shown that the pericardium and its contents play an essential anti-fibrotic role in the ischemic rodent model (coronary ligation to induce myocardial injury). The majority of pre-clinical myocardial infarction models require the disruption of pericardial integrity with loss of the homeostatic cellular milieu. However, recently a methodology has been developed by us to induce myocardial infarction, which minimizes pericardial damage and retains the heart&#39;s resident immune cell population. An improved cardiac functional recovery in mice with an intact pericardial space following coronary ligation has been observed. This method provides an opportunity to study inflammatory responses in the pericardial space following myocardial infarction. Further development of the labeling techniques can be combined with this model to understand the fate and function of pericardial immune cells in regulating the inflammatory mechanisms that drive remodeling in the heart, including fibrosis.

This protocol outlines the steps for inducing myocardial infarction in mice while preserving the pericardium and its contents.

Um modelo de roedor isquêmico de pericárdio intacto

This protocol has shown that the pericardium and its contents play an essential anti-fibrotic role in the ischemic rodent model (coronary ligation to ...

Generation and Characterization of Right Ventricular Myocardial Infarction Induced by Permanent Ligation of the Right Coronary Artery in Mice

Right ventricular infarction (RVI) is a common presentation in clinical practice. Severe RVI can lead to fatal hemodynamic dysfunction and arrhythmia. In contrast to the extensively used mouse myocardial infarction (MI) model generated by left coronary artery ligation, the RVI mouse model is rarely employed due to the difficulty associated with model generation. Research on the mechanisms and treatment of RVI-induced RV remodeling and dysfunction requires animal models to mimic the pathophysiology of RVI in patients. This study introduces a feasible procedure for RVI model generation in C57BL/6J mice. Further, this model was characterized based on the following: infarct size evaluation at 24 h after MI, assessment of cardiac remodeling and function with echocardiography, RV hemodynamics assessment, and histology of the infarct zone at 4 weeks after RVI. In addition, a coronary vasculature cast was performed to observe the coronary arterial arrangement in RV. This mouse model of RVI would facilitate the research on mechanisms of right heart failure and seek new therapeutic targets of RV remodeling.

There are several differences between the right and left ventricles. However, the pathophysiology of right ventricular infarction (RVI) has not been clarified. In the present protocol, a reproducible method for RVI mouse model generation is introduced, which may provide a means to explain the mechanism of RVI.

Geração e Caracterização do Infarto do Miocárdio Ventricular Direito Induzido pela Ligação Permanente da Artéria Coronária Direita em Camundongos

Right ventricular infarction (RVI) is a common presentation in clinical practice. Severe RVI can lead to fatal hemodynamic dysfunction and arrhythmia. In ...

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

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

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

Implante de Cardiomiócitos Derivados de Células-Tronco Pluripotentes Induzidos por Ultrassom em Camundongos Infartados do Miocárdio

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

An Experimental Model of Myocardial Infarction for Studying Cardiac Repair and Remodeling in Knockout Mice

Cardiovascular disease is the most prevalent cause of death in Western countries, with acute myocardial infarction (MI) being the most prevalent form. This paper describes a protocol for studying the role of galectin 3 (Gal-3) in the temporal evolution of cardiac healing and remodeling in an experimental animal model of MI. 
The procedures described include an experimental model of MI with a permanent coronary ligature in male C57BL/6J (control) and Gal-3 knockout (KO) mice, an echocardiography procedure to study cardiac remodeling and systolic function in vivo, a histological evaluation of interstitial myocardial fibrosis with picrosirius red-stained and rhodamine-conjugated lectin-stained sections for studying myocyte hypertrophy by the cross-sectional area (MCSA), and the quantification of infarct size and cardiac remodeling (scar thinning, septum thickness, and expansion index) by planimetry in slices stained with Masson's trichrome and triphenyl tetrazolium chloride. Gal-3 KO mice with MI showed disrupted cardiac remodeling and an increase in the scar thinning ratio and the expansion index. At the onset of MI, myocardial function and cardiac remodeling were also severely affected. At 4 weeks post MI, the natural evolution of fibrosis in infarcted Gal-3 KO mice was also affected. 
In summary, the experimental model of MI is a suitable model for studying the temporal evolution of cardiac repair and remodeling in mice with the genetic deletion of Gal-3 and other animal models. The lack of Gal-3 affects the dynamics of cardiac repair and disrupts the evolution of cardiac remodeling and function after MI.

Here, we describe an experimental model of myocardial infarction, an echocardiography procedure to study cardiac remodeling and function, and procedures for quantifying fibrosis and hypertrophy in picrosirius red-stained and rhodamine-stained sections, as well as the infarct size and expansion index in slices stained with Masson's trichrome.

Cardiovascular disease is the most prevalent cause of death in Western countries, with acute myocardial infarction (MI) being the most prevalent form. ...