Este trabalho foi financiado pelo programa de intercâmbio FY 2013 pesquisa entre JSPS e CNRS, JSPS KAKENHI Grant número 26860858 e a neurociência Narishige Research Foundation. Agradecemos os Drs Mariko Harada-Shiba e Kyoko Shioya discussões úteis. Agradecemos a Mari Furuta, Mutsumi Sakamoto, Ritsuko Maki e Dr. Emi Tanaka pela excelente assistência técnica.

Todos os experimentos foram realizados em conformidade com os protocolos aprovados pelo Comitê de uso do nacional Cerebral e o centro do sistema circulatório, Suita, Japão e cuidado de Animal Experimental.
1. prepare os seguintes animais e materiais para cirurgia MIUH
<ol><li>Preparar a grávida cronometrado Sprague-Dawley ratos no dia gestacional 17, ou seja, a embrionário dia 17 (E17). Pesos de corpo médio a barragens são 307.0 ± 40,7 g (média ± DP, n = 9).</li>
	<li>Prepare-se suportes metálicos; diâmetro interno 0,24 mm, feito de aço revestido de ouro.</li>
	<li>Prepare todos os materiais de acordo com a tabela de materiais.</li>
</ol>2. preparar para a cirurgia MIUH
<ol><li>Aquecer uma almofada de aquecimento a 37 ° C, para a colocação de rato</li>
	<li>Coloque uma fralda estéril sobre a almofada de aquecimento</li>
	<li>Solução salina estéril aquecida a 37 ° C em banho-maria</li>
</ol>3. realizar cirurgia MIUH
<ol><li>Realize procedimentos cirúrgicos sob condição estéril. Esterilize as bobinas, pinça, agulha com etanol a 70% antes do uso. Usar luvas estéreis e ocasionalmente desinfete aplicando spray de etanol.</li>
	<li>Coloque o rato na caixa de indução de anestesia. Introduza a 4% de isoflurano em caixa (aproximadamente 5 min).</li>
	<li>Coloque o rato sobre uma fralda estéril sobre a almofada de aquecimento em uma posição supina depois que o animal é completamente anestesiado na caixa de indução. Verifique a profundidade da anestesia pela falta de uma resposta a uma pitada de dedo do pé. Manter o isoflurano 1,5-2,0% com um cone de nariz.</li>
	<li>Aplicam-se desde o umbigo até a região do arco pélvica depilatório espuma sobre o abdômen. Após vários minutos, limpe a espuma depilatório com uma toalha de papel. Uma máquina de barbear pode ser usada como um substituto para a espuma depilatório.</li>
	<li>Aplica gaze embebida em solução desinfetante iodo à região depilada da pele.</li>
	<li>Coloque um pano cirúrgico com uma abertura redonda para cobrir o abdômen que não seja a área da incisão cirúrgica. Vários pedaços de gaze podem ser usados como um substituto para a cortina.</li>
	<li>Usando um bisturi cirúrgico, faça uma incisão de aproximadamente 2,5 cm comprimento na parte inferior do abdome da borda superior do osso púbico para cima em direção ao umbigo. Em seguida, fazer uma incisão através da camada muscular por baixo.</li>
	<li>Coloque vários pedaços de gaze estéril ao redor da abertura da cortina e molhar a gaze com solução salina aquecida.</li>
	<li>Empurre a ambas as partes laterais do abdômen suavemente, para que uma porção do corno uterino emerge a incisão.</li>
	<li>Desinfecte as mãos do cirurgião com etanol a 70%.</li>
	<li>Puxe delicadamente o todo corno uterino da cavidade abdominal manualmente sem o uso de fórceps. Usando a pinça cirúrgica não é aconselhável, pois pode facilmente danificar útero frágil, fetos e vasos sanguíneos compactando-os fortemente e desigualmente.</li>
	<li>Coloque o corno uterino sobre a gaze molhada.</li>
	<li>Execute o mesmo procedimento para o outro corno uterino.</li>
	<li>Conte o número de fetos.</li>
	<li>Aplica a solução salina aquecida com frequência para manter o útero quente e úmido durante a cirurgia.<ol>
<li>Mude a fralda quando ele tem absorvido muito soro fisiológico. Para manter a estabilidade, repita as luvas de desinfecção com 70% de etanol e dicas do instrumento com iodo. Manter os dedos não estéreis longe as pontas estéril do instrumento é crucial.</li>
	</ol>
</li>
	<li>Identifica a parte proximal da arcada principal das artérias uterinas e dos ovários sob um estereomicroscópio. Nota: É fundamental distinguir os ramos a arcada principal para as placentas. Note-se que a intervenção cirúrgica pode ser mais fácil quando o corno uterino é invertido. Ocasionalmente, aplicar uma bobina na parte proximal muito do arcade é difícil, porque está localizado profundamente na cavidade abdominal e artérias da placenta são muito próximas a parte proximal do arcade. Neste caso, uma bobina pode ser aplicada a uma parte da arcada após os garfos de filial primeiros fora.</li>
	<li>Separar a artéria de veia correndo paralela a ela com a pinça e fazer o espaço entre eles.</li>
	<li>Coloque um pedaço de corda (seda sutura 4.0, 5 cm de comprimento) embaixo da artéria.</li>
	<li>Levante ambas as extremidades da cadeia de caracteres com pinças para que a artéria é levantada e separou a veia frágil.</li>
	<li>Segurando a borda do microcoil com pinça fina na outra mão, coloque um microcoil ao lado da artéria levantada (Figura 2.1).</li>
	<li>Gire a artéria levantada usando a corda em torno do microcoil para embrulhar o microcoil ao redor da artéria. É mais fácil girar a artéria em torno da bobina do que ao girar a bobina em torno da artéria (Figura 2.2).</li>
	<li>Depois de girar a artéria 3 ou 4 espiras (bobinas tem 5 voltas), alterar o local no qual a bobina é realizada para a outra borda. Segure a borda da bobina que tem sido envolvida em torno da artéria com fórceps. Altere o local no qual a sequência de caracteres levanta a artéria para o outro lado da bobina. Girar a artéria em torno da bobina para que a bobina completamente (5 voltas) envolve a artéria (Figura 2.3, 2.4).</li>
	<li>Remova a sequência de caracteres.</li>
	<li>Execute o mesmo procedimento para as outras três artérias.</li>
	<li>Observe que, frequentemente, aplicando soro aquecido para o útero é crucial; caso contrário, aumenta a taxa de mortalidade de fetos e hipotermia pode ser neuroprotective.</li>
	<li>Retorne suavemente o corno uterino na cavidade abdominal. Levantamento de uma borda da incisão da parede abdominal com fórceps pode facilitar este procedimento.</li>
	<li>Stich o músculo abdominal e em seguida stich a pele abdominal com sutura (sutura de seda 4.0). Amarre a sutura após cada stich, ou seja, interrompidas suturas simples.</li>
	<li>Aplica gaze embebida em solução desinfetante iodo em e ao redor da incisão cirúrgica.</li>
	<li>Administre o analgésico meloxicam em 0,5 mg/kg de peso corporal por via subcutânea.</li>
	<li>Permitem a 30 min de recuperação em uma gaiola aquecida. Seleção de animais se totalmente acordado e andando ao redor da gaiola, retornam a gaiola em casa.</li>
</ol>

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Os autores não têm nada para divulgar.

A microcoil estenose das artérias ovarianos e uterinas em ambos os cornos uterinos produz hipoperfusão intra-uterino consistente e reprodutível em todas as placentas e fetos. O nível de hipoperfusão pode ser modificado usando suportes com diferentes diâmetros internos. Filhotes nascidos de uma represa em que foi executada estenose da artéria com suportes 0,24 mm de diâmetro interno demonstram IUGR e parto prematuro (ver referência 1 para obter detalhes). Os filhotes apresentam alterações comportamentais e neur...

Lactentes com restrição de crescimento intra-uterino (IUGR) (também conhecido como restrição de crescimento fetal) (peso de nascimento < 10th percentil para a idade gestacional), parto prematuro (nascido em < 37 semanas de gestação), e/ou baixa conta peso (< 2500 g) para a luz quase 10% de todos os recém-nascidos 2,3. Muitas destas crianças apresentam problemas neurológicos, como paralisia cerebral e transtornos globais do desenvolvimento (por exemplo, transtorno déficit/hiperatividade (TDAH) e distúrbios de aprendizagem) 3,4,5. Essas condições têm semelhanças e diferenças em sua etiologia e os resultados. A etiologia da IUGR é multifatorial, e insuficiência placentária, associada com hipoperfusão intra-uterina é considerada a causa mais comum em fetos não-anômala 7. A etiologia do prematuro também é multifatorial, e Corioamnionite é a causa mais frequente 8.
Desconhece-se a influência de leve hipoperfusão intra-uterino (MIUH) no encéfalo em desenvolvimento. Atualmente disponíveis modelos animais de hipoperfusão/isquemia intra-uterina envolvem principalmente a hipoperfusão severa ou grau gradiente de hipoperfusão com ou sem reperfusão 9,10,11. Em ambientes clínicos, no entanto, casos de MIUH são considerados muito mais frequentes do que aqueles que envolvem tais condições severas. Os modelos atualmente disponíveis de MIUH são um modelo roedor envolvendo ligadura de sutura de útero ou a artéria ovárica e um modelo de roedor que envolvem as artérias de ovário bilaterais e aorta tendo patência 12,13, de recorte 14,15,16,17. Uma das desvantagens destes modelos é a extensa variabilidade inter feto, variando de fetos com hipoperfusão profunda para fetos com perfusão quase intacto, dependendo da posição do feto dentro da arcada arterial do útero e artérias dos ovários. Outra desvantagem destes modelos é sua incapacidade de distinguir a posição de cada feto após o nascimento; daí, os pesquisadores não consegue distinguir a gravidade de hipoperfusão intra-uterino experimentada por um cachorro individual após o seu nascimento.
Nós desenvolvemos um modelo do rato de MIUH envolvendo múltiplos de estenose de artéria 1. Envolvimento de metais microbobinas com diâmetro interno de 0,24 mm ao redor das artérias uterinas e dos ovários provoca estenose, mas não de obstrução, dos vasos sanguíneos (Figura 1). Aplicar estes suportes na parte proximal do todas as artérias fornecendo o útero, ou seja, as artérias uterinas e ovarianos bilaterais, embrionárias dia 17 (equivalente a embrionárias semanas 20-25 em seres humanos 18) induz uma diminuição significativa, mas suave o fluxo de sangue para a placenta e fetos. A diminuição do fluxo sanguíneo após bobinas são aplicadas a todos os quatro artérias alimentando o útero em grande parte é os mesmos em cada placenta e feto. A taxa de mortalidade de feto é inferior a 20%. Os filhotes nascem através do trabalho de parto espontâneo 1-2 dias anteriores (embrionário dia 21-22) do que o normal. Quase todos os filhotes nascem exibindo nascimento significativamente mais baixos pesos 1. Volumes de matéria cinzenta e branca são diminuídos sem dano no tecido óbvio 1. Filhotes apresentam atrasada aquisição de reflexos do recém-nascido, fraqueza muscular e alteração espontânea atividade 1. Este modelo imita os sinais e sintomas clínicos de crianças nascidas prematuramente ou com IUGR; exposição de prematuros nascidos filhos reduzida cinza e volume de substância branca, com ou sem substância branca lesão 6, presente atrasado Marcos do desenvolvimento neurológico e pode apresentar problemas comportamentais, tais como TDAH 3,5; crianças com IUGR exibem alterações neuroanatômica mínimas e têm um risco aumentado de anomalias do desenvolvimento neurológico como atraso motor e cognitivo 4,7. Parto prematuro e IUGR são condições diferentes, mas as duas condições compartilham o mecanismo básico, ou seja, insultos ao seu cérebro imaturo antes da idade gestacional de termo.

<table><tbody><tr><td>Stereomicroscope</td><td></td><td></td><td></td></tr><tr><td>Isoflurane anesthesia machine</td><td></td><td></td><td></td></tr><tr><td>Anesthesia induction box</td><td></td><td></td><td></td></tr><tr><td>Heating pad</td><td></td><td></td><td></td></tr><tr><td>Diaper 30x40 cm</td><td></td><td></td><td></td></tr><tr><td>Depilatory foam or shaver</td><td></td><td></td><td></td></tr><tr><td>Iodine disinfectant solution</td><td></td><td></td><td></td></tr><tr><td>Gauze 10x20 cm&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Surgical drape 45x45 cm with a round opening 5 cm in diameter</td><td></td><td></td><td></td></tr><tr><td>Spray bottle with ethanol for disinfection</td><td></td><td></td><td></td></tr><tr><td>Cotton swab</td><td></td><td></td><td></td></tr><tr><td>Forceps with large blunt tips</td><td></td><td></td><td></td></tr><tr><td>Forceps with angled fine tips</td><td></td><td></td><td></td></tr><tr><td>Scissors</td><td></td><td></td><td></td></tr><tr><td>Surgical scalpel, blade size is 27mm long (no.10, Axel, AS ONE Corporation, Osaka, Japan)</td><td></td><td></td><td></td></tr><tr><td>Surgical suture needle</td><td></td><td></td><td></td></tr><tr><td>Metal microcoils; inner diameter 0.24 mm, made from gold-coated steel (SAMINI Co. Ltd., Shizuoka, Japan)</td><td></td><td></td><td></td></tr><tr><td>Silk suture 4-0</td><td></td><td></td><td></td></tr><tr><td>Sterile saline (0.9% sodium chloride)</td><td></td><td></td><td></td></tr><tr><td>Heating water bath</td><td></td><td></td><td></td></tr><tr><td>Plastic syringes (50ml) and needles (18G)</td><td></td><td></td><td></td></tr></tbody></table>

a rat model of mild intrauterine hypoperfusion with microcoil stenosis

Hipoperfusão/isquemia intra-uterina é uma das principais causas de restrição do crescimento intra-uterino/fetal, parto prematuro e baixo peso ao nascer. A maioria dos estudos desse fenômeno foram realizados em ambos modelos com grave isquemia intra-uterina ou modelos com grau gradiente de hipoperfusão intra-uterina. Nenhum estudo foi realizado em um modelo de uniforme suave intra-uterino hipoperfusão (MIUH). Dois modelos têm sido utilizados para estudos de MIUH: um modelo baseado em ligadura de sutura de ambos os lados da arcada arterial formado com as artérias uterinas e dos ovários, e um modelo transiente com base no recorte as artérias de ovário bilaterais e aorta tendo patência. Esses dois modelos de roedores de MIUH tem algumas limitações, por exemplo, nem todos os fetos são sujeitas a MIUH, dependendo de sua posição no corno uterino. Em nosso modelo MIUH, todos os fetos são submetidos a um nível comparável de hipoperfusão intra-uterina. MIUH foi alcançado por estenose leve de todos os quatro artérias alimentando o útero, ou seja, as artérias uterinas e ovarianos bilaterais.
Estenose arterial foi induzido por suportes de metal enrolado as artérias de alimentação. Produzir estenose arterial com suportes permitida-nos controlar, otimizar e reproduzir a diminuição do fluxo sanguíneo com pouca variabilidade de animal para animal e uma baixa mortalidade, permitindo uma avaliação exata. Quando foram utilizados suportes de 0,24 mm de diâmetro interno, o fluxo de sangue na placenta e feto foi ligeiramente reduzida (cerca de 30% do nível pre-estenose na placenta). A descendência de nosso modelo MIUH claramente demonstra alterações de longa duração em resultados de testes neurológicos, neuroanatômica e comportamentais.

Após a aplicação de suportes para todas as artérias alimentando o útero, ou seja, as artérias uterinas e ovarianos bilaterais, todos os fetos estão sujeitos a níveis comparáveis de hipoperfusão. A aplicação de suportes com um diâmetro interno de 0,24 mm causa estenose leve essas artérias, causando uma leve diminuição no fluxo sanguíneo para a placenta e fetos (Figura 3; cerca de 30% do nível pre-estenose na placenta, ver referência 1 para o...

Watch this Scientific Journal Video about A Rat Model of Mild Intrauterine Hypoperfusion with Microcoil Stenosis at JoVE.com

A Rat Model of Mild Intrauterine Hypoperfusion with Microcoil Stenosis

Leve hipoperfusão intra-uterina foi produzido por estenose da artéria com suportes de metal enrolado as artérias uterinas e dos ovários em ratos em embrionário dia 17. Este procedimento produziu hipoperfusão pré-natal e restrição de crescimento intra-uterino.

Um modelo do rato de leve hipoperfusão intra-uterino com estenose Microcoil

Intrauterine hypoperfusion/ischemia is one of the major causes of intrauterine/fetal growth restriction, preterm birth, and low birth weight. Most studies ...

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JoVE Journal

Neuroscience

10.2K visualizações.  National Cerebral and Cardiovascular Center. Leve hipoperfusão intra-uterina foi produzido por estenose da artéria com suportes de metal enrolado as artérias uterinas e dos ovários em ratos em embrionário dia 17. Este procedimento produziu hipoperfusão pré-natal e restrição de crescimento intra-uterino.

Vídeo: A Rat Model of Mild Intrauterine Hypoperfusion with Microcoil Stenosis

The Hypoxic Ischemic Encephalopathy Model of Perinatal Ischemia

Hypoxic-Ischemic Encephalopathy (HIE) is the consequence of systemic asphyxia occurring at birth. Twenty five percent of neonates with HIE develop severe and permanent neuropsychological sequelae, including mental retardation, cerebral palsy, and epilepsy. The outcomes of HIE are devastating and permanent, making it critical to identify and develop therapeutic strategies to reduce brain injury in newborns with HIE. To that end, the neonatal rat model for hypoxic-ischemic brain injury has been developed to model this human condition. The HIE model was first validated by Vannucci et al 1 and has since been extensively used to identify mechanisms of brain injury resulting from perinatal hypoxia-ischemia 2 and to test potential therapeutic interventions 3,4. The HIE model is a two step process and involves the ligation of the left common carotid artery followed by exposure to a hypoxic environment. Cerebral blood flow (CBF) in the hemisphere ipsilateral to the ligated carotid artery does not decrease because of the collateral blood flow via the circle of Willis; however with lower oxygen tension, the CBF in the ipsilateral hemisphere decreases significantly and results in unilateral ischemic injury. The use of 2,3,5-triphenyltetrazolium chloride (TTC) to stain and identify ischemic brain tissue was originally developed for adult models of rodent cerebral ischemia 5, and is used to evaluate the extent of cerebral infarctin at early time points up to 72 hours after the ischemic event 6. In this video, we demonstrate the hypoxic-ischemic injury model in postnatal rat brain and the evaluation of the infarct size using TTC staining.

The postnatal rat model for hypoxic-ischemic brain injury is a well-established model of human neonatal hypoxic ischemic encephalopathy (HIE). In this article, we describe the model of HIE in post-natal rat pups.

O Modelo de encefalopatia hipóxico isquêmica Perinatal da Isquemia

Hypoxic-Ischemic Encephalopathy (HIE) is the consequence of systemic asphyxia occurring at birth. Twenty five percent of neonates with HIE develop severe ...

Biologia

Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction

Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ultrasound and fetal echocardiography. Increasingly, these imaging modalities are being employed clinically to examine cardiac function and assess wellbeing in utero, thereby guiding timing of birth decisions. Here, we used a rabbit model of IUGR that allows analysis of cardiac function in a clinically relevant way. Using isoflurane induced anesthesia, IUGR is surgically created at gestational age day 25 by performing a laparotomy, exposing the bicornuate uterus and then ligating 40-50% of uteroplacental vessels supplying each gestational sac in a single uterine horn. The other horn in the rabbit bicornuate uterus serves as internal control fetuses. Then, after recovery at gestational age day 30 (full term), the same rabbit undergoes examination of fetal cardiac function. Anesthesia is induced with ketamine and xylazine intramuscularly, then maintained by a continuous intravenous infusion of ketamine and xylazine to minimize iatrogenic effects on fetal cardiac function. A repeat laparotomy is performed to expose each gestational sac and a microultrasound examination (VisualSonics VEVO 2100) of fetal cardiac function is performed. Placental insufficiency is evident by a raised pulsatility index or an absent or reversed end diastolic flow of the umbilical artery Doppler waveform. The ductus venosus and middle cerebral artery Doppler is then examined. Fetal echocardiography is performed by recording B mode, M mode and flow velocity waveforms in lateral and apical views. Offline calculations determine standard M-mode cardiac variables, tricuspid and mitral annular plane systolic excursion, speckle tracking and strain analysis, modified myocardial performance index and vascular flow velocity waveforms of interest. This small animal model of IUGR therefore affords examination of in utero cardiac function that is consistent with current clinical practice and is therefore useful in a translational research setting.

We describe examination of fetal cardiac function with contemporary functional fetal echocardiography and fetoplacental Doppler ultrasound using the VisualSonics VEVO 2100 microultrasound in a surgically induced model of intrauterine fetal growth restriction in a rabbit.

Ecocardiografia fetal e ultra-som Doppler pulsátil em um modelo de coelho de restrição do crescimento intra-uterino

Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ...

Medicina

Transuterine Fetal Tracheal Occlusion Model in Mice

Fetal tracheal occlusion (TO), an established treatment modality, promotes fetal lung growth and survival in severe congenital diaphragmatic hernia (CDH). Following TO, retention of the secreted epithelial fluid increases luminal pressure and induces lung growth. Various animal models have been defined to understand the pathophysiology of CDH and TO. All have their own advantages and disadvantages such as the difficulty of the technique, the size of the animal, cost, high mortality rates, and the availability of genetic tools. Herein, a novel transuterine model of murine fetal TO is described. Pregnant mice were anesthetized, and the uterus exposed via a midline laparotomy. The trachea of selected fetuses were ligated with a single transuterine suture placed behind the trachea, one carotid artery, and one jugular vein. The dam was closed and allowed to recover. Fetuses were collected just before parturition. Lung to body weight ratio in TO fetuses was higher than that in control fetuses. This model provides researchers with a new tool to study the impact of both TO and increased luminal pressure on lung development.

Various animal models of congenital diaphragmatic hernia and fetal tracheal occlusion present advantages and disadvantages regarding ethical issues, cost, surgical difficulty, size, survival rates, and availability of genetic tools. This model provides a new tool to study the impact of both tracheal occlusion and increased luminal pressure on lung development.

Modelo de oclusão traqueal fetal transuterina em camundongos

Fetal tracheal occlusion (TO), an established treatment modality, promotes fetal lung growth and survival in severe congenital diaphragmatic hernia (CDH). ...

Biologia do Desenvolvimento

Stenosis of the Inferior Vena Cava: A Murine Model of Deep Vein Thrombosis

Deep vein thrombosis (DVT) and its devastating complication, pulmonary embolism, are a severe health problem with high mortality. Mechanisms of thrombus formation in veins remain obscure. Lack of mobility (e.g., after surgery or long-haul flights) is one of the main factors leading to DVT. The pathophysiological consequence of the lack of mobility is blood flow stagnation in venous valves. Here, a model is described that mimics such flow disturbance as a thrombosis-driving factor. In this model, partial flow restriction (stenosis) in the inferior vena cava (IVC) is created. Closure of about 90% of the IVC lumen for 48 h results in development of thrombi structurally similar to those in humans. The similarities are: i) most of the thrombus volume is red, i.e., consists of red blood cells and fibrin, ii) presence of a white part (lines of Zahn), iii) non-denuded endothelial monolayer, iv) elevated plasma D-Dimer levels, and v) possibility to prevent thrombosis by low molecular weight heparin. Limitations include variable size of thrombi and the fact that a certain percentage of wild-type mice (0 - 35%) may not produce a thrombus. In addition to visual observation and measurement, thrombi may be visualized by non-invasive technologies, such as ultrasonography, which allows for monitoring the dynamics of thrombus development. At shorter time points (1 - 6 h), intravital microscopy may be applied to directly observe events (e.g., recruitment of cells to the vessel wall) preceding thrombus formation. Use of this method by several teams around the world has made it possible to uncover basic mechanisms of DVT initiation and identify potential targets that might be beneficial for its prevention.

We describe here stenosis in the inferior vena cava as a murine model of deep vein thrombosis. This model recapitulates blood flow restriction, one of the major triggers of venous thrombosis in humans.

Estenose da veia Cava Inferior: um modelo murino de trombose venosa profunda

Deep vein thrombosis (DVT) and its devastating complication, pulmonary embolism, are a severe health problem with high mortality. Mechanisms of thrombus ...

Imunologia e Infecção

Transient Middle Cerebral Artery Occlusion Model of Neonatal Stroke in P10 Rats

A number of animal models have been used to study hypoxic-ischemic injury, traumatic injury, global hypoxia, or permanent ischemia in both the immature and mature brain. Stroke occurs commonly in the perinatal period in humans, and transient ischemia-reperfusion is the most common form of stroke in neonates. The reperfusion phase is a critical component of injury progression, which occurs over a period of days to weeks, and of the endogenous response to injury. This postnatal day 10 (p10) rat model of transient middle cerebral artery occlusion (tMCAO) creates a unilateral, non-hemorrhagic focal ischemia-reperfusion injury that can be utilized to study the mechanisms of focal injury and repair in the full-term-equivalent brain. The injury pattern that is produced by tMCAO is consistent and highly reproducible and can be confirmed with MRI or histological analyses. The severity of injury can be manipulated through changes in occlusion time and other methods that will be discussed.

Neonatal stroke is a significant cause of early brain injury requiring a translational model with consistent focal injury patterns and high reproducibility in order to enable study. This study describes the detailed surgical procedure for creating a non-hemorrhagic, unilateral focal ischemia-reperfusion injury in full-term-equivalent rodents.

Transiente Artéria Cerebral Média Oclusão Modelo de AVC neonatal em ratos P10

A number of animal models have been used to study hypoxic-ischemic injury, traumatic injury, global hypoxia, or permanent ischemia in both the immature ...

Murine Model of Central Venous Stenosis using Aortocaval Fistula with an Outflow Stenosis

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ligation of the inferior vena cava (IVC) in the outflow of the fistula, mimicking central venous stenosis. Technical aspects of this model are introduced. The aorta and IVC are exposed, following an abdominal incision. The infra-renal aorta and IVC are dissected for proximal clamping, and the distal aorta is exposed for puncture. The IVC at the midpoint between the left renal vein and the aortic bifurcation is carefully dissected to place an 8-0 suture beneath the IVC. After clamping the aorta and IVC, an AVF is created by puncturing the infra-renal aorta through both walls into the IVC with a 25 G needle, followed by ligating a 22 G intra-venous (IV) catheter and IVC together. The catheter is then removed, creating a reproducible venous stenosis without occlusion. The aorta and IVC are unclamped after confirming primary hemostasis. This novel model of central vein stenosis is easy to perform, reproducible, and will facilitate studies on AVF failure.

An aortocaval fistula was created by puncturing the murine infra-renal aorta through both walls into the inferior vena cava and was followed by creation of a stenosis in its outflow via partial ligation of the inferior vena cava. This reproducible model can be used to study central venous stenosis.

Modelo murino de estenose venosa central usando fístula Aortocaval com estenose de saída

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ...

Real-Time Assessment of Spinal Cord Microperfusion in a Porcine Model of Ischemia/Reperfusion

Spinal cord injury is a devastating complication of aortic repair. Despite developments for the prevention and treatment of spinal cord injury, its incidence is still considerably high and therefore, influences patient outcome. Microcirculation plays a key role in tissue perfusion and oxygen supply and is often dissociated from macrohemodynamics. Thus, direct evaluation of spinal cord microcirculation is essential for the development of microcirculation-targeted therapies and the evaluation of existing approaches in regard to spinal cord microcirculation. However, most of the methods do not provide real-time assessment of spinal cord microcirculation. The aim of this study is to describe a standardized protocol for real-time spinal cord microcirculatory evaluation using laser-Doppler needle probes directly inserted in the spinal cord. We used a porcine model of ischemia/reperfusion to induce deterioration of the spinal cord microcirculation. In addition, a fluorescent microsphere injection technique was used. Initially, animals were anesthetized and mechanically ventilated. Thereafter, laser-Doppler needle probe insertion was performed, followed by the placement of cerebrospinal fluid drainage. A median sternotomy was performed for exposure of the descending aorta to perform aortic cross-clamping. Ischemia/reperfusion was induced by supra-celiac aortic cross-clamping for a total of 48 min, followed by reperfusion and hemodynamic stabilization. Laser-Doppler Flux was performed in parallel with macrohemodynamic evaluation. In addition, automated cerebrospinal fluid drainage was used to maintain a stable cerebrospinal pressure. After completion of the protocol, animals were sacrificed, and the spinal cord was harvested for histopathological and microsphere analysis. The protocol reveals the feasibility of spinal cord microperfusion measurements using laser-Doppler probes and shows a marked decrease during ischemia as well as recovery after reperfusion. Results showed comparable behavior to fluorescent microsphere evaluation. In conclusion, this new protocol might provide a useful large animal model for future studies using real-time spinal cord microperfusion assessment in ischemia/reperfusion conditions.

Spinal cord microcirculation plays a pivotal role in spinal cord injury. Most methods do not allow real-time assessment of spinal cord microcirculation, which is essential for the development of microcirculation-targeted therapies. Here, we propose a protocol using Laser-Doppler-Flow Needle probes in a large animal model of ischemia/reperfusion.

Avaliação em tempo real da microperfusão da medula espinhal em um modelo suíno de isquemia/reperfusão

Spinal cord injury is a devastating complication of aortic repair. Despite developments for the prevention and treatment of spinal cord injury, its ...

Myocardial Infarction by Percutaneous Embolization Coil Deployment in a Swine Model

Myocardial infarction (MI) is the leading cause of mortality worldwide. Despite the use of evidence-based treatments, including coronary revascularization and cardiovascular drugs, a significant proportion of patients develop pathological left-ventricular remodeling and progressive heart failure following MI. Therefore, new therapeutic options, such as cellular and gene therapies, among others, have been developed to repair and regenerate injured myocardium. In this context, animal models of MI are crucial in exploring the safety and efficacy of these experimental therapies before clinical translation. Large animal models such as swine are preferred over smaller ones due to the high similarity of swine and human hearts in terms of coronary artery anatomy, cardiac kinetics, and the post-MI healing process. Here, we aimed to describe an MI model in pig by permanent coil deployment. Briefly, it comprises a percutaneous selective coronary artery cannulation through retrograde femoral access. Following coronary angiography, the coil is deployed at the target branch under fluoroscopic guidance. Finally, complete occlusion is confirmed by repeated coronary angiography. This approach is feasible, highly reproducible, and emulates the pathogenesis of human non-revascularized MI, avoiding the traditional open-chest surgery and the subsequent postoperative inflammation. Depending on the time of follow-up, the technique is suitable for acute, sub-acute, or chronic MI models.

Myocardial infarction (MI) animal models that emulate the natural process of the disease in humans are crucial to understanding pathophysiological mechanisms and testing the safety and efficacy of new emergent therapies. Here, we describe an MI swine model created by deploying a percutaneous embolization coil.

Infarto do Miocárdio por implantação de bobina de embolização percutânea em um modelo de suíno

Myocardial infarction (MI) is the leading cause of mortality worldwide. Despite the use of evidence-based treatments, including coronary revascularization ...

Early Pathological and Magnetic Resonance Detection of Cerebral Injury Using a Rat Model of Neonatal Hypoxic Ischemic Encephalopathy

Perinatal hypoxic-ischemic encephalopathy (HIE) is an acute disease that may afflict newborns, resulting in variable long- and short-term neurodevelopmental outcomes. Early diagnosis is critical to identifying infants who may benefit from intervention; however, early diagnosis relies heavily on clinical criteria. No molecular or radiological tests have shown promise in detecting early cerebral injury. Studies have shown that magnetic resonance imaging (MRI) can show changes in both blood flow/ischemia and metabolic disruption. However, they have all been used to evaluate the secondary phase of the disease (&gt;12 h) after the onset of the injury. Early diagnosis is critical to rapidly starting therapeutic hypothermia in eligible infants, which is currently recommended to be initiated within 6 h of birth. The rat model of hypoxic-ischemic injury was developed in 1981 and has been validated and used extensively to study changes in brain perfusion, cerebral injury markers, and morphology. However, it has primarily been used as a "late model", evaluating injury several days after the initial ischemic insult. The model has been known to have poor sensitivity in evaluating reliable and reproducible early cerebral changes. The objective of this study was to develop a reliable model to study early gross morphological and radiological markers of HIE using pathological staining and cerebral magnetic resonance imaging/magnetic resonance spectroscopy.

The present protocol describes a rodent model of newborn hypoxic-ischemic injury for identifying early changes in cerebral tissue by gross morphology and magnetic resonance imaging. This has benefits over existing models, which can be used to study late injury but do not allow the evaluation of reproducible early changes.

Perinatal hypoxic-ischemic encephalopathy (HIE) is an acute disease that may afflict newborns, resulting in variable long- and short-term ...

Bandagem Aórtica Ascendente para Estudo da Insuficiência Cardíaca Induzida por Sobrecarga de Pressão

A Minimally Invasive Model of Aortic Stenosis in Swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological similarities to humans. Efforts have been dedicated to creating a model of pressure-overload induced heart failure, and ascending aortic banding while still supra-coronary and not a perfect mimic of aortic stenosis in humans, closely resembling the human condition.
The purpose of this study is to demonstrate a minimally invasive approach to induce left ventricular pressure overload by placing an aortic band, precisely calibrated with percutaneously introduced high-fidelity pressure sensors. This method represents a refinement of the surgical procedure (3Rs), resulting in homogenous trans-stenotic gradients and reduced intragroup variability. Additionally, it enables swift and uneventful animal recovery, leading to minimal mortality rates. Throughout the study, animals were followed for up to 2 months after surgery, employing transthoracic echocardiography and pressure-volume loop analysis. However, longer follow-up periods can be achieved if desired. This large animal model proves valuable for testing new drugs, particularly those targeting hypertrophy and the structural and functional alterations associated with left ventricular pressure overload.

Autor em destaque: Desenvolvimento de um modelo minimamente invasivo de animais de grande porte para pesquisa cardiovascular confiável e reprodutível 

This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

Modelo Minimamente Invasivo de Estenose Aórtica em Suínos

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological ...