Name: the inverted heart model for interstitial transudate collection from the isolated rat heart
Uploaded: 2017-06-20T15:00:00
Description: Watch this Scientific Journal Video about The Inverted Heart Model for Interstitial Transudate Collection from the Isolated Rat Heart at JoVE.com

This study was funded by NSFC 81570244, FoKo 23/2013, and SFB 1116/B01 and by the Cardiovascular Research Institute D&#252;sseldorf (CARID).

All experiments were approved by the local regulatory agency (LANUV of Nordrhein-Westfalen, Germany) and were performed according to the guidelines of animal use. Animals were fed with a standard chow diet and received tap water ad libitum. All equipment and chemicals necessary to each step of the experiment are available in the Table of Materials.
1. Preparation of the Latex Cap and Intraventricular Balloon
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	<li>Make an aluminum mold using a milling m...

<ol>
	<li>Henkel, D. M., Redfield, M. M., Weston, S. A., Gerber, Y., Roger, V. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Death+in+heart+failure:+a+community+perspective.">Death in heart failure: a community perspective.</a> Circ Heart Fail. 1 (2), 91-97 (2008).</li><li>Limana, F., 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=Myocardial+infarction+induces+embryonic+reprogramming+of+epicardial+c-kit(+)+cells:+role+of+the+pericardial+fluid.">Myocardial infarction induces embryonic reprogramming of epicardial c-kit(+) cells: role of the pericardial fluid.</a> J Mol Cell Cardiol. 48 (4), 609-618 (2010).</li><li>Brunner, F. <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+endothelin-1+levels+under+basal,+stimulated,+and+ischemic+conditions.">Cardiac tissue endothelin-1 levels under basal, stimulated, and ischemic conditions.</a> J Cardiovasc Pharmacol. 26, S44-S46 (1995).</li><li>de Lannoy, L. 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Local production of angiotensin I.</a> Hypertension. 29 (6), 1240-1251 (1997).</li><li>Strupp, M., Kammermeier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interstitial+Lactate+And+Glucose-Concentrations+Of+the+Isolated-Perfused+Rat-Heart+before,+during+And+after+Anoxia.">Interstitial Lactate And Glucose-Concentrations Of the Isolated-Perfused Rat-Heart before, during And after Anoxia.</a> Pflugers Arch. 423 (3-4), 232-237 (1993).</li><li>Wienen, W., Jungling, E., Kammermeier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzyme-Release+into+the+Interstitial+Space+of+the+Isolated+Rat-Heart+Induced+by+Changes+in+Contractile+Performance.">Enzyme-Release into the Interstitial Space of the Isolated Rat-Heart Induced by Changes in Contractile Performance.</a> Cardiovasc Res. 28 (8), 1292-1298 (1994).</li><li>De Deckere, E. A., Ten Hoor, ., P, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+modified+Langendorff+technique+for+metabolic+investigations.">A modified Langendorff technique for metabolic investigations.</a> Pflugers Arch. 370 (1), 103-105 (1977).</li><li>Tschubar, F., Rose, H., Kammermeier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fatty+acid+transfer+across+the+myocardial+capillary+wall.">Fatty acid transfer across the myocardial capillary wall.</a> J Mol Cell Cardiol. 25 (4), 355-366 (1993).</li><li>Wienen, W., Kammermeier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intra-+and+extracellular+markers+in+interstitial+transudate+of+perfused+rat+hearts.">Intra- and extracellular markers in interstitial transudate of perfused rat hearts.</a> Am J Physiol. 254 (4 Pt 2), H785-H794 (1988).</li><li>Sasse, A., Ding, Z. P., Wallich, M., Godecke, A., Schrader, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+transfer+of+adenovirus+is+augmented+by+nitric+oxide+in+the+rat+heart.">Vascular transfer of adenovirus is augmented by nitric oxide in the rat heart.</a> Am J Physiol Heart Circ Physiol. 287 (3), H1362-H1368 (2004).</li><li>Gnecchi, M., Zhang, Z., Ni, A., Dzau, V. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Paracrine+mechanisms+in+adult+stem+cell+signaling+and+therapy.">Paracrine mechanisms in adult stem cell signaling and therapy.</a> Circ Res. 103 (11), 1204-1219 (2008).</li><li>Herr, D. J., Aune, S. E., Menick, D. 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(101), e52908 (2015).</li><li>Ding, Z., 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=Epicardium-Derived+Cells+Formed+After+Myocardial+Injury+Display+Phagocytic+Activity+Permitting+In+Vivo+Labeling+and+Tracking.">Epicardium-Derived Cells Formed After Myocardial Injury Display Phagocytic Activity Permitting In Vivo Labeling and Tracking.</a> Stem Cells Transl Med. 5 (5), 639-650 (2016).</li><li>Hartwig, S., 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=Secretome+profiling+of+primary+human+skeletal+muscle+cells.">Secretome profiling of primary human skeletal muscle cells.</a> Biochim Biophys Acta. 1844 (5), 1011-1017 (2014).</li><li>Smolenski, R. T., Lachno, D. R., Ledingham, S. J. M., Yacoub, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+sixteen+nucleotides,+nucleosides+and+bases+using+high-performance+liquid+chromatography+and+its+application+to+the+study+of+purine+metabolism+in+hearts+for+transplantation.">Determination of sixteen nucleotides, nucleosides and bases using high-performance liquid chromatography and its application to the study of purine metabolism in hearts for transplantation.</a> J Chromatogr. 527 (2), 414-420 (1990).</li><li>Decking, U. K., Juengling, E., Kammermeier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interstitial+transudate+concentration+of+adenosine+and+inosine+in+rat+and+guinea+pig+hearts.">Interstitial transudate concentration of adenosine and inosine in rat and guinea pig hearts.</a> Am J Physiol. 254 (6 Pt 2), H1125-H1132 (1988).</li><li>Heller, L. J., Mohrman, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimates+of+interstitial+adenosine+from+surface+exudates+of+isolated+rat+hearts.">Estimates of interstitial adenosine from surface exudates of isolated rat hearts.</a> J Mol Cell Cardiol. 20 (6), 509-523 (1988).</li></ol>

The reversed-heart model is based on the well-established Langendorff heart perfusion technique12 and is performed by simply inverting the heart into an upside-down position and holding this position using a rigid intra-ventricular balloon catheter. In such a way, cardiac interstitial transudate can be physically separated from coronary venous effluent perfusate, dripping by gravity from the base of the heart9. The CT can be continuously collected by means of a thin and fle...

Heart failure (HF) is the leading cause of death in humans worldwide1. HF often occurs because of myocarditis, ischemic insults to the myocardium, and left ventricular remodeling, leading to the progressive deterioration of cardiac contractile function and patients&#39; quality of life. Although advances in cardiology and cardiac surgery have remarkably lowered HF mortality, they merely serve as transient &#34;delayers&#34; of an inevitably progressive disease process that carries signi&#64257;cant morbidity. Therefore, the current lack of effective treatment underscores the need to identify novel molecular targets that can prevent or even reverse HF. This includes changes in the extracellular matrix, uncontrolled cardiac immune response, and interactions between cardiac and non-cardiac cells2.
It is important to recognize that the microenvironment that cardiac cells are exposed to directly shapes the immune and regenerative response of the injured heart. In the isolated, saline-perfused heart, CT is generated on the heart surface in the form of small droplets that are derived from the interstitial fluid space (i.e., microenvironment), both under physiological and pathophysiological conditions3,4,5. Therefore, analysis of the CT (i.e., interstitial fluid) may help to identify factors that regulate cardiac metabolism and contractile function6 or influence immune cell functions after migration into the injured heart. Potentially, this may lead to the development of novel therapeutic strategies for the treatment of HF.
The collection of CT from murine hearts is technically challenging. In regular Langendorff-perfused hearts, the exclusive collection of CT is difficult because the mixture of the CT with coronary venous effluent perfusate unpredictably dilutes any concentration of metabolites/enzymes released from the interstitial space. One possible strategy to overcome this limitation is to exclude the venous effluent by cannulating the pulmonary and simultaneously ligating the pulmonary vein7. However, this method faces difficulties associated with the cannulation and ligation of the pulmonary artery and vein, causing potential leakage of venous effluent into the cardiac transudate. The concept of using a reverse heart model was first introduced by the group of Kammermeier, who inverted the isolated, perfused heart into an upside-down position and placed a thin latex cap on the epicardial surface to continuously sample CT without the contamination of venous effluent8,9. Using this procedure, CT was shown to provide a very sensitive measure of the metabolites released from the heart9, the capillary transfer of fatty acids8, and viral particles10.
More recently, paracrine factors that may regulate the local immune response and augment cardiac angiogenesis11 have been implicated in the beneficial effects of stem cell-based therapy for heart disease. The analysis of CT in the reversed heart may help to chemically identify these individual paracrine factors. In addition, CT may help to identify the factors involved in the in vivo activation of immune cells in the heart.
The detailed description of CT collection from the heart surface, provided here, is experimentally useful for researchers studying the interplay of immune cells, fibroblasts, endothelial cells, and cardiomyocytes in relation to overall cardiac function. As mentioned above, the interstitial fluid carries the information for cell-to-cell communication within the heart, which can conveniently be assessed by the collection of CT. The detailed technical description, including a video protocol of how to collect CT from the reversed heart, should facilitate the future application of this unique technique.

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the inverted heart model for interstitial transudate collection from the isolated rat heart

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. After isolation and retrograde perfusion of the heart according to the Langendorff technique, the heart is inverted into an upside-down position and is mechanically stabilized by a balloon catheter inserted into the left ventricle. Then, a thin latex cap &#8211; previously cast to match the average size of the rat heart &#8211; is placed over the epicardial surface. The outlet of the latex cap is connected to silicon tubing, with the distal opening 10 cm below the base level of the heart, creating slight suction. CT continuously produced on the epicardial surface is collected in ice-cooled vials for further analysis. The rate of CT formation ranged from 17 to 147 &#181;L/min (n = 14) in control and infarcted hearts, which represents 0.1-1% of the coronary venous effluent perfusate. Proteomic analysis and high performance liquid chromatography (HPLC) revealed that the collected CT contains a wide spectrum of proteins and purinergic metabolites.

The reversed-heart model enables the collection of cardiac interstitial transudate in an isolated, retro-perfused rat heart (Figure 1A-C). When perfused at a constant pressure of 100 cmH2O, the rate of interstitial fluid formation ranged between 17 and 147 &#181;L/min, amounting to 0.1-1% of the coronary venous effluent in the isolated heart.
The protein content of the CT...

Watch this Scientific Journal Video about The Inverted Heart Model for Interstitial Transudate Collection from the Isolated Rat Heart at JoVE.com

The Inverted Heart Model for Interstitial Transudate Collection from the Isolated Rat Heart

This protocol describes a method to collect cardiac interstitial fluid from the isolated, perfused rat heart. To physically separate interstitial transudate from coronary venous effluent perfusate, the Langendorff perfused heart is inverted, and the transudate (interstitial fluid) formed on the cardiac surface is collected using a soft latex cap.

The present protocol describes a unique approach that enables the collection of cardiac transudate (CT) from the isolated, saline-perfused rat heart. ...

The overall goal of this inverted heart model is to collect cardiac interstitial transudate from an isolate rat heart. Within the beating heart, the individual sense of the heart release paracrine factors and they release those into the surrounding interstitial fluid space. This is important, because the interstitial fluid space, it carries information for the communication between the cardiac cells.And that is particularly important under conditions of inflammation and regeneration of the infarcted myocardium. In this video, my collaborators, Dr.Ding and Tan, will show you the techniques by which we here, in this uh-love collect interstitial fluid from the surface of an isolated perfused rat heart. To make the latex heart cover, or cap, have an aluminum mold that matches the average size of a rat's heart and has been polished with superfine emery paper.Vertically fix the neck of the mold to the milling machine and start to slowly rotate the mold. Then, pour 20 milliliters of liquid latex into a 50 milliliter glass beaker, and lower the rotating mold into the latex until it is immersed. Then, slowly lift it out and keep rotating the mold for an additional 15 minutes until the latex has solidified.The rotation is vital to make this mousse and evenly distribute layer of the liquid latex on the mold's surface. So, make certain that the mold is rotating as it is lifted from the latex. Once the latex is dry, coat the latex with talcum powder to prevent damage to the latex.Stop the rotation, then gently detach the mold from the machine. Carefully remove the latex from the mold. Now, attach a 25 centimeter length of silicon tubing to the outlet on the latex cap.This tube is used to collect the interstitial cardiac transudate, or CT.Next, firmly attach the rat-sized ventricular balloon onto an L-shaped metal cannula, connected to a one milliliter water-filled syringe. And fill the rat-sized ventricular balloon with water. Make sure that the balloon is airtight by inflating and deflating it several times using the syringe.Then, connect the cannula to a pressure transducer, via a three way stop. Lastly, make a mark on the syringe where the balloon will fill the ventricular cavity for the measurement of intraventricular pressure. Before proceeding with preparation of the heart, ready the Langendorff perfusion system according to the text protocol.Now, after fully anesthetizing a 300 to 350 gram male Wistar rat, transfer it to a room temperature operating table. With experience, the following steps leading to the cannulation of the heart should only take about three minutes. Lift the skin and muscle just below the sternum, using forceps, and cut around the lower margin of the ribs using heavy scissors.Next, with fine scissors, make a small cut into the diaphragm at the rib margin. Next, cut the rib's caudally to make a flap of the entire ventral chest wall. Now, gently take hold of the heart, and slowly life it until the cardiac vessels start to stretch.Then, excise the heart until the aorta is fully exposed and transfer the heart to a 100 milliliter beaker containing 50 milliliters of ice cold KHB. Now, immediately take the heart to the profusion apparatus, and mount the aorta onto a dripping cannula. Secure it tightly with a 4-0 suture, so that no air bubbles can enter the heart.Then, apply either a constant profusion pressure or a profusion flow. To establish the reversed heart set up, first gently rotate the aortic cannula until the posterior wall of the hart is en face. Then, snip away the connective tissue to expose the opening to the left atrium.Next, gently grasp the heart and turn it upside-down. Mount the heart onto the prepared ventricular balloon, with the balloon deflated, and feed it into the left ventricle. The heart is now mechanically stabilized in an upright position, using the balloon catheter assembly as a support.Inflate the balloon until it fills the entire ventricular cavity, by advancing the plunger to the fill mark. Secure the heart so there is minimal stress on the aortic root. This part of the procedure takes practice.Now, observe the gauge on the balloon, and adjust the diastolic pressure to three to five millimeters of mercury. Small droplets should form on the epicardium if the pressure is set correctly. Next, gently pull the latex cap over the heart.Even the most ventricular surface should be covered. Before proceeding, check for air bubbles inside the cap. To remove any air bubbles, use gentle suction from the syringe.Now, position the end of the letting tube 10 centimeters below the heart. Collect the dripping CT into a 1.5 milliliter tube and keep the tube below four degrees Celsius by embedding it in a 1:1 mixture of ice and sodium chloride. Collect between 0.15 and 1.5 milliliters of CT, then weight the sample and snap freeze it in liquid nitrogen.Store it at minus 80 degrees Celsius until it can be processed. When retroperfusing the reversed heart model at a constant pressure of 100 centimeters of water, between 1/10 to 1%of the coronary venous effluent could be collected. The protein content of the CT was measured with the BCA assay, and averaged 1.1 milligram per milliliter.Simple gel electrophoresis revealed a wide spectrum of proteins. Normal samples were compared to samples from hearts subjected to 50 minutes of ischemia reperfusion using 2D DIGE. Several protein were found to be upregulated in the CT of the ischemic hearts.Proteomic analysis was performed on the upregulated proteins. Purines were also of great interest. Purines are pivotal signaling molecules that regulate the cardiac immune response, vasomotor tone, and cardiac function, particularly after ischemic injury.HPLC analysis of the CT showed elevated concentrations of many purines in the injured hearts. While attempting this procedure, it's important to remember that a cardiac trans-in-date being formed in an isolated heart, will not entirely mimic the true composition of the in-vee-vuh conditions.

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Research

JoVE Journal

Medicine

Orthotopic Aortic Transplantation: A Rat Model to Study the Development of Chronic Vasculopathy

Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant vasculopathy (TVP).
The commonly used animal model for cardiovascular chronic rejection studies is the heterotopic heart transplant model performed in laboratory rodents. This model is used widely in experiments since Ono and Lindsey (3) published their technique. To analyze the findings in the blood vessels, the heart has to be sectioned and all vessels have to be measured.
Another method to investigate chronic rejection in cardiovascular questionings is the aortic transplant model (1, 2). In the orthotopic aortic transplant model, the aorta can easily be histologically evaluated (2). The PVG-to-ACI model is especially useful for CAV studies, since acute vascular rejection is not a major confounding factor and Cyclosporin A (CsA) treatment does not prevent the development of CAV, similar to what we find in the clinical setting (4). A7-day period of CsA is required in this model to prevent acute rejection and to achieve long-term survival with the development of TVP.
This model can also be used to investigate acute cellular rejection and media necrosis in xenogeneic models (5).

This video demonstrates the orthotopic aortic transplant model as a simple model to study the development of transplant vasculopathy (TVP) in rats.

Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant ...

Implantation of Total Artificial Heart in Congenital Heart Disease

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. 
In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. 
Due to the patient's grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient's ventricles and great arteries required modifications to the TAH during implantation.
With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification.

This is a case report of a patient with congenitally corrected transposition of the great arteries (CCTGA) who received a total artificial heart (TAH) as a bridge to heart transplant. The TAH was successfully implanted with modifications to accommodate the patient's congenitally malformed heart.

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital ...

An Isolated Working Heart System for Large Animal Models

Since its introduction in the late 19th century, the Langendorff isolated heart perfusion apparatus, and the subsequent development of the working heart model, have been invaluable tools for studying cardiovascular function and disease1-15. Although the Langendorff heart preparation can be used for any mammalian heart, most studies involving this apparatus use small animal models (e.g., mouse, rat, and rabbit) due to the increased complexity of systems for larger mammals1,3,11. One major difficulty is ensuring a constant coronary perfusion pressure over a range of different heart sizes &#8211; a key component of any experiment utilizing this device1,11. By replacing the classic hydrostatic afterload column with a centrifugal pump, the Langendorff working heart apparatus described below allows for easy adjustment and tight regulation of perfusion pressures, meaning the same set-up can be used for various species or heart sizes. Furthermore, this configuration can also seamlessly switch between constant pressure or constant flow during reperfusion, depending on the user&#8217;s preferences. The open nature of this setup, despite making temperature regulation more difficult than other designs, allows for easy collection of effluent and ventricular pressure-volume data.

Most studies involving the Langendorff apparatus use small animal models due to the increased complexity of systems for larger mammals. We describe a Langendorff system for large animal models that allows for use across a range of species, including humans, and relatively easy data acquisition.

Since its introduction in the late 19th century, the Langendorff isolated heart perfusion apparatus, and the subsequent development of the working heart ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

Murine Isolated Heart Model of Myocardial Stunning Associated with Cardioplegic Arrest

The following protocol is of use to evaluate impaired cardiac function or myocardial stunning following moderate ischemic insults. The technique is useful for modeling ischemic injury associated with numerous clinically relevant phenomenon including cardiac surgery with cardioplegic arrest and cardiopulmonary bypass, off-pump CABG, transplant, angina, brief ischemia, etc. The protocol presents a general method to model hypothermic hyperkalemic cardioplegic arrest and reperfusion in rodent hearts focusing on measurement of myocardial contractile function. In brief, a mouse heart is perfused in langendorff mode, instrumented with an intraventricular balloon, and baseline cardiac functional parameters are recorded. Following stabilization, the heart is then subject to brief infusion of a cardioprotective hypothermic cardioplegia solution to initiate diastolic arrest. Cardioplegia is delivered intermittently over 2 hr. The heart is then reperfused and warmed to normothermic temperatures and recovery of myocardial function is monitored. Use of this protocol results in reliable depressed cardiac contractile function free from gross myocardial tissue damage in rodents.

The goal of this protocol to assess myocardial stunning following ischemic cardioplegic arrest in rodents.

The following protocol is of use to evaluate impaired cardiac function or myocardial stunning following moderate ischemic insults. The technique is useful ...

Repeated Blood Collection from Tail Vein of Non-Anesthetized Rats with a Vacuum Blood Collection System

Blood can be collected from rats in a number of sampling locations. For instance, the tail vein is a superior location for blood sampling. However, the tail vein is thin so that it is sometimes hard to puncture. In addition, the tail vein has low blood flow and requires a long sampling time to get sufficient blood. The present report describes a simple blood sampling method, the vacuum blood collection method, which is usually used to obtain blood samples from patients, here used for non-anesthetized rats. The 22 G butterfly needle tip was inserted into one of the lateral tail veins approximately 2-3 cm from the tip of the tail at an angle of approximately 20&#176;, and blood was collected in the vacuum collection tube by inserting the rubber end of the butterfly needle into the vacuum blood collection tube. The present experimental results show that the success rate was 95% in the experimental group and 90% in the beginner group. The success rate and puncture times were similar between two groups. The sampling duration was significantly shorter in the experimental group compared to beginner group. In conclusion, this vacuum blood collection method for sequential blood sampling from the tail vein of non- anesthetized rats is feasible and easy-to-learn, which might serve as a reliable alternative to other conventionally used blood sampling techniques for rats.

Here, we describe a simple tail vein blood sampling method in non-anesthetized rats using a vacuum extraction tube system. This method reduces the risk of direct exposure to blood and simplifies taking multiple samples from a single venipuncture.

Blood can be collected from rats in a number of sampling locations. For instance, the tail vein is a superior location for blood sampling. However, the ...

Isolation of Atrial Cardiomyocytes from a Rat Model of Metabolic Syndrome-related Heart Failure with Preserved Ejection Fraction

In this article, we describe an optimized, Langendorff-based procedure for the isolation of single-cell atrial cardiomyocytes (ACMs) from a rat model of metabolic syndrome (MetS)-related heart failure with preserved ejection fraction (HFpEF). The prevalence of MetS-related HFpEF is rising, and atrial cardiomyopathies associated with atrial remodeling and atrial fibrillation are clinically highly relevant as atrial remodeling is an independent predictor of mortality. Studies with isolated single-cell cardiomyocytes are frequently used to corroborate and complement in vivo findings. Circulatory vessel rarefication and interstitial tissue fibrosis pose a potentially limiting factor for the successful single-cell isolation of ACMs from animal models of this disease.
We have addressed this issue by employing a device capable of manually regulating the intraluminal pressure of cardiac cavities during the isolation procedure, substantially increasing the yield of morphologically and functionally intact ACMs. The acquired cells can be used in a variety of different experiments, such as cell culture and functional Calcium imaging (i.e., excitation-contraction-coupling).
We provide the researcher with a step-by-step protocol, a list of optimized solutions, thorough instructions to prepare the necessary equipment, and a comprehensive troubleshooting guide. While the initial implementation of the procedure might be rather difficult, a successful adaptation will allow the reader to perform state-of-the-art ACM isolations in a rat model of MetS-related HFpEF for a broad spectrum of experiments.

Here, we describe an optimized, Langendorff-based procedure for the isolation of single-cell atrial cardiomyocytes from a rat model of metabolic syndrome-related heart failure with preserved ejection fraction. A manual regulation of intraluminal pressure of cardiac cavities is implemented to yield functionally intact myocytes suitable for excitation-contraction-coupling studies.

In this article, we describe an optimized, Langendorff-based procedure for the isolation of single-cell atrial cardiomyocytes (ACMs) from a rat model of ...

A Cryoinjury Model to Study Myocardial Infarction in the Mouse

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we demonstrate a murine cryoinjury infarct model that generates precise infarct sizes with high reproducibility and replicability. In brief, after intubation and sternotomy of the animal, the heart is lifted from the thorax. The probe of a handheld liquid nitrogen delivery system is applied onto the myocardial wall to induce cryoinjury. Impaired ventricular function and electrical conduction can be monitored with echocardiography or optical mapping. Transmural myocardial remodeling of the infarcted area is characterized by collagen deposition and loss of cardiomyocytes. Compared to other models (e.g., LAD-ligation), this model utilizes a handheld liquid nitrogen delivery system to generate more uniform infarct sizes.

This article demonstrates a model to study cardiac remodeling after myocardial cryoinjury in mice.

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we ...

An Image Guided Transapical Mitral Valve Leaflet Puncture Model of Controlled Volume Overload from Mitral Regurgitation in the Rat

Mitral regurgitation (MR) is a widely prevalent heart valve lesion, which causes cardiac remodeling and leads to congestive heart failure. Though the risks of uncorrected MR and its poor prognosis are known, the longitudinal changes in cardiac function, structure and remodeling are incompletely understood. This knowledge gap has limited our understanding of the optimal timing for MR correction, and the benefit that early versus late MR correction may have on the left ventricle. To investigate the molecular mechanisms that underlie left ventricular remodeling in the setting of MR, animal models are necessary. Traditionally, the aorto-caval fistula model has been used to induce volume overload, which differs from clinically relevant lesions such as MR. MR represents a low-pressure volume overload hemodynamic stressor, which requires animal models that mimic this condition. Herein, we describe a rodent model of severe MR in which the anterior leaflet of the rat mitral valve is perforated with a 23G needle, in a beating heart, with echocardiographic image guidance. The severity of MR is assessed and confirmed with echocardiography, and the reproducibility of the model is reported.&#160;&#160;

A rodent model of left heart volume overload from mitral regurgitation is reported. Mitral regurgitation of controlled severity is induced by advancing a needle of defined dimensions into the anterior leaflet of the mitral valve, in a beating heart, with ultrasound guidance.&#160;

Mitral regurgitation (MR) is a widely prevalent heart valve lesion, which causes cardiac remodeling and leads to congestive heart failure. Though the ...

In Vivo Heart Transplantation to Study Endothelial-to-Mesenchymal Transition

A Neonatal Heterotopic Rat Heart Transplantation Model for the Study of Endothelial-to-Mesenchymal Transition

Endocardial fibroelastosis (EFE), defined by subendocardial tissue accumulation, has major impacts on the development of the left ventricle (LV) and precludes patients with congenital critical aortic stenosis and hypoplastic left heart syndrome (HLHS) from curative anatomical biventricular surgical repair. Surgical resection is currently the only available therapeutic option, but EFE often recurs, sometimes with an even more infiltrative growth pattern into the adjacent myocardium.
To better understand the underlying mechanisms of EFE and to explore therapeutic strategies, an animal model suitable for preclinical testing was developed. The animal model takes into consideration that EFE is a disease of the immature heart and is associated with flow disturbances, as supported by clinical observations. Thus, the heterotopic heart transplantation of neonatal rat donor hearts is the basis for this model.
A neonatal rat heart is transplanted into an adolescent rat&#39;s abdomen and connected to the recipient&#39;s infrarenal aorta and inferior vena cava. While perfusion of the coronary arteries preserves the viability of the donor heart, flow stagnation within the LV induces EFE growth in the very immature heart. The underlying mechanism of EFE formation is the transition of endocardial endothelial cells to mesenchymal cells (EndMT), which is a well-described mechanism of early embryonic development of the valves and septa but also the leading cause of fibrosis in heart failure. EFE formation can be macroscopically observed within days after transplantation. Transabdominal echocardiography is used to monitor the graft viability, contractility, and the patency of the anastomoses. Following euthanasia, the EFE tissue is harvested, and it shows the same histopathological characteristics as human EFE tissue from HLHS patients.
This in vivo model allows for studying the mechanisms of EFE development in the heart and testing treatment options to prevent this pathological tissue formation and provides the opportunity for a more generalized examination of EndMT-induced fibrosis.

Author Spotlight: A Neonatal Heterotopic Rat Heart Transplantation Model for the Study of Endothelial-to-Mesenchymal Transition  

This work presents an animal model of endothelial-to-mesenchymal transition-induced fibrosis, as seen in congenital cardiac defects such as critical aortic stenosis or hypoplastic left heart syndrome, which allows for detailed histological tissue evaluation, the identification of regulatory signaling pathways, and the testing of treatment options.

Endocardial fibroelastosis (EFE), defined by subendocardial tissue accumulation, has major impacts on the development of the left ventricle (LV) and ...