Name: establishing a swine model of post-myocardial infarction heart failure for stem cell treatment
Uploaded: 2020-05-25T14:00:00
Description: Watch this Scientific Journal Video about Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment at JoVE.com

The authors acknowledge Alfreda and Kung Tak Chung for their excellent technical support during the animal experiments.

All animal experiments were performed in accordance with the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health and regulations of the University of Hong Kong, and the protocol was approved by the Committee on the Use of Live Animals in Teaching and Research (CULTAR) at the University of Hong Kong.
NOTE: Female farm pigs weighing 35-40 kg (9-12 months old) were used for this study. The flowchart of this experiment is shown in <strong class="xfig"...

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Standard animal models are of paramount importance to understand the pathophysiology and mechanisms of diseases and test novel therapeutics. Our protocol establishes a porcine model of HF induced by left circumflex artery blockage and rapid pacing. Eight weeks after the induction of MI, the animals developed significant impairment of LVEF, LVEDD, LVESD, +dP/dt, and ESPVR. This protocol also tests the administration method of stem cell therapy for heart regeneration by intramyocardial injection. The infarct size, and card...

Cardiovascular diseases, coronary artery disease (CAD) in particular, remain the major cause of morbidity and mortality in Hong Kong and worldwide1. In Hong Kong, a 26% increase from 2012 to 2017 of the number of CAD patients treated under the Hospital Authority was projected2. Among all CADs, acute myocardial infarction (MI) is a leading cause of death and subsequent complications, such as heart failure (HF). These contribute to significant medical, social, and financial burdens. In patients with MI, thrombolytic therapy or primary percutaneous coronary intervention (PCI) is an effective therapy in preserving life, but these therapies can only reduce cardiomyocyte (CM) loss during MI. The treatments available are unable to replenish the permanent loss of CMs, which leads to cardiac fibrosis, myocardial remodeling, cardiac arrhythmia, and eventually heart failure. The mortality rate at 1-year post-MI is around 7% with more than 20% patients developing HF3. In end-stage HF patients, heart transplantation is the only available effective therapy, but it is limited by a shortage of available organs. Novel therapies are necessary to reverse the development of post-MI HF. As a result, cell-based therapy is considered an attractive approach to repair the impaired CMs and ameliorate left ventricular (LV) function in HF following MI. Our previous studies found stem cell transplantation to be beneficial for heart function improvement after direct intramyocardial transplantation in small animal models of MI4,5. Standardized preclinical large animal HF protocols are thus needed to further test the efficacy and safety of stem cell transplantation before clinical use.
Recent decades have witnessed the widespread use of pigs in cardiovascular research for stem cell therapy. HF pigs are a promising model of translational research due to their similarity to humans in terms of cardiac size, weight, rhythm, function, and coronary artery anatomy. Moreover, porcine HF models can mimic post-MI HF patients in terms of CM metabolism, electrophysiological properties, and neuroendocrine changes under ischemic conditions6. The protocol presented here uses such a standardized pig HF model, employing a closed-chest coronary balloon occlusion of the left circumflex artery (LCX) followed by rapid pacing induced by pacemaker implantation. The study also optimizes the route of intramyocardial administration of stem cells for the treatment of post-MI HF. The purpose is to produce a porcine animal model of chronic myocardial infarction that can be used to develop treatments that are clinically relevant for patients with severe CAD.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Amiodarone</td>
			<td>Mylan</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Anaesthetic machines and respirator</td>
			<td>Drager</td>
			<td>Fabius plus XL</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Angiocath</td>
			<td>Becton Dickinson</td>
			<td>381147</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Anti-human nuclear antigen</td>
			<td>abcam</td>
			<td>ab19118</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Axio Plus image capturing system</td>
			<td>Zeiss</td>
			<td>Axioskop 2 PLUS</td>
			<td>Axioskop 2 plus</td>
		</tr>
		<tr>
			<td>AxioVision Rel. 4.5 software</td>
			<td>Zeiss</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Baytril</td>
			<td>Bayer</td>
			<td>-</td>
			<td>enrofloxacin</td>
		</tr>
		<tr>
			<td>Betadine</td>
			<td>Mundipharma</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>CardioLab Electrophysiology Recording Systems</td>
			<td>GE Healthcare</td>
			<td>G220f</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Culture media</td>
			<td>MesenCult</td>
			<td>05420</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Cyclosporine</td>
			<td>Novartis</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Defibrillator</td>
			<td>GE Healthcare</td>
			<td>CardioServ</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Dorminal</td>
			<td>TEVA</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Echocardiographic system</td>
			<td>GE Vingmed</td>
			<td>Vivid i</td>
			<td>-</td>
		</tr>
		<tr>
			<td>EchoPac software</td>
			<td>GE Vingmed</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Electrophysiological catheter</td>
			<td>Cordis Corp</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Embozene Microsphere</td>
			<td>Boston Scientific</td>
			<td>17020-S1</td>
			<td>700 &#956;m</td>
		</tr>
		<tr>
			<td>Endotracheal tube</td>
			<td>Vet Care</td>
			<td>VCPET70PCW</td>
			<td>Size 7</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>VWR chemicals</td>
			<td>20821.33</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Formalin</td>
			<td>Sigma</td>
			<td>HT501320</td>
			<td>10%</td>
		</tr>
		<tr>
			<td>IVC balloon Dilatation Catheter</td>
			<td>Boston Scientific</td>
			<td>3917112041</td>
			<td>Mustang</td>
		</tr>
		<tr>
			<td>JR4 guiding catheter</td>
			<td>Cordis Corp</td>
			<td>67208200</td>
			<td>6F</td>
		</tr>
		<tr>
			<td>Lidocaine</td>
			<td>Quala</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Mersilk</td>
			<td>Ethicon</td>
			<td>W584</td>
			<td>2-0</td>
		</tr>
		<tr>
			<td>Metoprolol succinate</td>
			<td>Wockhardt</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Microtome</td>
			<td>Leica</td>
			<td>RM2125RT</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Mobile C arm fluoroscopy equipment</td>
			<td>GE Healthcare</td>
			<td>OEC 9900 Elite</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Pacemaker</td>
			<td>St Jude Medical</td>
			<td>PM1272</td>
			<td>Assurity MRI pacemaker</td>
		</tr>
		<tr>
			<td>Pacemaker generator</td>
			<td>St Jude Medical</td>
			<td>Merlln model 3330</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Pressure-volume catheter</td>
			<td>CD Leycom</td>
			<td>CA-71103-PL</td>
			<td>7F</td>
		</tr>
		<tr>
			<td>Pressure&#8211;volume signal processor</td>
			<td>CD Leycom</td>
			<td>SIGMA-M</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Programmable Stimulator</td>
			<td>Medtronic Inc</td>
			<td>5328</td>
			<td>-</td>
		</tr>
		<tr>
			<td>PTCA Dilatation balloon Catheter</td>
			<td>Boston Scientific</td>
			<td>H7493919120250</td>
			<td>MAVERICK over the wire</td>
		</tr>
		<tr>
			<td>Ramipril</td>
			<td>TEVA</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Sheath introducer</td>
			<td>Cordis Corp</td>
			<td>504608X</td>
			<td>8F, 9F, 12F</td>
		</tr>
		<tr>
			<td>Steroid</td>
			<td>Versus Arthritis</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Temgesic</td>
			<td>Nindivior</td>
			<td>-</td>
			<td>buprenorphine</td>
		</tr>
		<tr>
			<td>Venous indwelling needle</td>
			<td>TERUMO</td>
			<td>SR+OX2225C</td>
			<td>22G</td>
		</tr>
		<tr>
			<td>Vicryl</td>
			<td>Ethicon</td>
			<td>VCP320H</td>
			<td>2-0</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Alfasan International B.V.</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Zoletil</td>
			<td>Virbac New Zealand Limited</td>
			<td>-</td>
			<td>tiletamine+zolezepam</td>
		</tr>
	</tbody>
</table>

establishing a swine model of post-myocardial infarction heart failure for stem cell treatment

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major causes of mortality and morbidity around the world. Cell-based therapies for cardiac repair and improvement of left ventricular function after MI have attracted considerable attention. Accordingly, the safety and efficacy of these cell transplantations should be tested in a preclinical large animal model of HF prior to clinical use. Pigs are widely used for cardiovascular disease research due to their similarity to humans in terms of heart size and coronary anatomy. Therefore, we sought to present an effective protocol for the establishment of a porcine chronic HF model using closed-chest coronary balloon occlusion of the left circumflex artery (LCX), followed by rapid ventricular pacing induced with pacemaker implantation. Eight weeks later, the stem cells were administered by intramyocardial injection in the peri-infarct area. Then the infarct size, cell survival, and left ventricular function (including echocardiography, hemodynamic parameters, and electrophysiology) were evaluated. This study helps establish a stable preclinical large animal HF model for stem cell treatment.

Mortality 
A total of 24 pigs were used in this study. Three of them died during MI induction because of sustained VT. One animal died in the open-heart surgery for cell injection because of wound bleeding. Two animals died because of severe infection. Two animals were excluded because of slight EF reduction (LVEF reduction &#62; 40% of baseline). As a result, 16 animals completed the whole study protocol.
...

Watch this Scientific Journal Video about Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment at JoVE.com

Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment

We sought to establish a swine model of heart failure induced by left circumflex artery blockage and rapid pacing to test the effect and safety of intramyocardial administration of stem cells for cell-based therapies.

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major ...

This swine heart failure model, induced by left circumflex artery blockage and rapid pacing, can be used to assess the effects of direct intramyocardial stem cell injection on heart regeneration. Our swine colony heart failure model is quite stable. The new infarct size of this model is around 16%of left ventricle and left ventricle injection infarction reduced by at least 40%from baseline.With the experimental pig fixed in the supine position, locate the right carotid artery and juggler vein in the carotid triangle, and use hemostatic forceps and aseptic technique to isolate the right carotid artery and jugular vein. Ligate the distal end of the right carotid artery and juggler vein and use an angiocath to cannulate the right juggler vein. After inserting a pacemaker lead into the right ventricle under x-ray guidance use forceps to isolate the sternocleidomastoid and anterior scalene muscles and connect the pacemaker to the lead.Then implant a pacemaker between the two muscles. Then close the two muscles with 2-0 silk. To assess changes in left ventricle function, isolate the right femoral artery and femoral vein in the femoral triangle, and calculate the right femoral artery with an angiocath.Place a guidewire into the femoral vein via the angiocath and remove the angiocath. Cannulate a 12 French sheath into the femoral vein under the guidance of the guidewire and remove the guidewire. Cannulate the right femoral artery with a nine French sheath as just demonstrated.And insert a balloon catheter through the 12 French sheath into the interior vena cava under x-ray guidance. Calibrate a seven French pressure volume catheter in isotonic saline with a pressure volume signal processor and insert the catheter into the left ventricle apex through the nine French sheath under x-ray guidance. Suspend the ventilation and use the pressure volume signal processor to measure the left ventricle maximal and negative pressure derivative, and systolic pressure and end diastolic pressures.Then restart the ventilation. For myocardial infarction induction, administer five milligrams per kilogram amiodarone and 1.5 milligrams per kilogram lidocaine bolus intravenously over one hour to prevent ventricular arrhythmias before calculating the right carotid artery with an eight French sheath as demonstrated. Perform the coronary angiography through a six French sheath over-the-wire guiding catheter via the placed sheath guided by standard C arm fluoroscopy.Occlude to the left circumflex coronary artery distal to the first obtuse marginal branch with percutaneous transluminal coronary angioplasty dilation balloon catheter inflation under x-ray guidance. Load one milliliter of 700 micrometers sponge microspheres mixed with seven milliliters of iohexol in a 10 milliliter syringe and inject the mixture through the balloon catheter to block the left circumflex coronary artery. Then deflate the balloon and perform an angiogram to confirm the occlusion.Eight weeks after infarction induction load two times 10 to the eighth human-induced pluripotent stem cell-derived mesenchymal stem cells in two milliliters of normal saline into a five milliliter syringe and sterilize 10 centimeters around the apex beat area of the anesthetized experimental animal. Use a retractor to perform a left thoracotomy at the four or five intercostal space and perform a pericardiotomy to expose the infarcted lateral wall. When the infarcted areas visible, perform five to eight intra myocardial injections of approximately 300 microliters of cells per injection before closing the intercostal space with iron wire and closing the muscle layer with 2-0 silk sutures and the subcutaneous tissues and skin layers with 2-0 vicryl sutures.To assess the inducibility of ventricular tachyarrhythmia after cell therapy, insert a six French electrophysiological catheter into the right ventricular apex via the femoral vein and display the intracardiac recordings with the surface electrocardiogram leas I, II, and III on the electrophysiological recording system at a speed of 200 millimeters per second. Use a stimulator to deliver a two millisecond pulse width at two times the diastolic threshold and deliver a pacing train of eight stimuli at one 200 millisecond and one 300 millisecond drive cycle length followed by one or two premature extra stimuli. Then sequentially shortened the coupling intervals until the ventricular effective refractory period of arrhythmia is induced, noting the presence of an inducible sustained ventricular tachyarrhythmia.In this representative experiment, serial echocardiographic examination showed that the left ventricle ejection fraction significantly decreased from baseline while the left ventricle end-diastolic dimension and end systolic dimension significantly increased at eight weeks after myocardial infarction induction. In contrast, the left ventricle ejection fraction significantly increased and the end systolic dimension remarkably decreased in the cell transplantation group eight weeks after administration. The negative pressure derivative and end systolic pressure volume relationship significantly decreased from baseline at eight weeks after induction of myocardial infarction while intramyocardial administration of mesenchymal stem cells resulted in an increase in these functions.Measurement of the left ventricle infarct wall thickness in five to seven serial one centimeter thick sections from each animal revealed a percentage of left ventricle infarction of approximately 16%There was no cell survival around the injection site in the infarct area eight weeks after transplantation. But a small number of the surviving injected stem cells were visible in the periinfarct area. The incidents of inducible sustained ventricular tachyarrhythmias could be easily increased in animals with heart failure.Of note, stem cell transplantation did not significantly modify the underlying myocardial substrate to reduce susceptibility to ventricular tachyarrhythmia. As left circumflex coronary artery blockage may induce arrhythmia. Be sure to monitor the ECG and to immediately use external biphasic defibrillator to re-establish sinuses as necessary.This method provide a stable and reproducible clinically relevant large animal model of heart failure for testing the efficacy of stem cell-based therapies.

establishing-swine-model-post-myocardial-infarction-heart-failure-for

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 ...

Gene Transfer for Ischemic Heart Failure in a Preclinical Model

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine their efficacy and safety.
Gene therapy using viral vectors is one of the most promising approaches for treating cardiac diseases. Viral delivery of various different genes by changing the carrier gene has immeasurable therapeutic potential.
In this video, the full process of an animal model of heart failure creation followed by gene transfer is presented using a swine model. First, myocardial infarction is created by occluding the proximal left anterior descending coronary artery. Heart remodeling results in chronic heart failure. Unique to our model is a fairly large scar which truly reflects patients with severe heart failure who require aggressive therapy for positive outcomes. After myocardial infarct creation and development of scar tissue, an intracoronary injection of virus is demonstrated with simultaneous nitroglycerine infusion. Our injection method provides simple and efficient gene transfer with enhanced gene expression. This combination of a myocardial infarct swine model with intracoronary virus delivery has proven to be a consistent and reproducible methodology, which helps not only to test the effect of individual gene, but also compare the efficacy of many genes as therapeutic candidates.

A method of gene transfer for the treatment of ischemic heart failure is described using a swine model of myocardial infarction. Our simple and reproducible method enables us to readily evaluate the efficacy of various gene transfers with a very simple and reproducible way.

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine ...

A Swine Model of Neonatal Asphyxia

Annually more than 1 million neonates die worldwide as related to asphyxia. Asphyxiated neonates commonly have multi-organ failure including hypotension, perfusion deficit, hypoxic-ischemic encephalopathy, pulmonary hypertension, vasculopathic enterocolitis, renal failure and thrombo-embolic complications. Animal models are developed to help us understand the patho-physiology and pharmacology of neonatal asphyxia. In comparison to rodents and newborn lambs, the newborn piglet has been proven to be a valuable model. The newborn piglet has several advantages including similar development as that of 36-38 weeks human fetus with comparable body systems, large body size (&tilde;1.5-2 kg at birth) that allows the instrumentation and monitoring of the animal and controls the confounding variables of hypoxia and hemodynamic derangements.
We here describe an experimental protocol to simulate neonatal asphyxia and allow us to examine the systemic and regional hemodynamic changes during the asphyxiating and reoxygenation process as well as the respective effects of interventions. Further, the model has the advantage of studying multi-organ failure or dysfunction simultaneously and the interaction with various body systems. The experimental model is a non-survival procedure that involves the surgical instrumentation of newborn piglets (1-3 day-old and 1.5-2.5 kg weight, mixed breed) to allow the establishment of mechanical ventilation, vascular (arterial and central venous) access and the placement of catheters and flow probes (Transonic Inc.) for the continuously monitoring of intra-vascular pressure and blood flow across different arteries including main pulmonary, common carotid, superior mesenteric and left renal arteries. Using these surgically instrumented piglets, after stabilization for 30-60 minutes as defined by Z&lt;10% variation in hemodynamic parameters and normal blood gases, we commence an experimental protocol of severe hypoxemia which is induced via normocapnic alveolar hypoxia. The piglet is ventilated with 10-15% oxygen by increasing the inhaled concentration of nitrogen gas for 2h, aiming for arterial oxygen saturations of 30-40%. This degree of hypoxemia will produce clinical asphyxia with severe metabolic acidosis, systemic hypotension and cardiogenic shock with hypoperfusion to vital organs. The hypoxia is followed by reoxygenation with 100% oxygen for 0.5h and then 21% oxygen for 3.5h. Pharmacologic interventions can be introduced in due course and their effects investigated in a blinded, block-randomized fashion.

Large animal models have good translational values in the examination of physiology and pharmacology of neonatal asphyxia. Using newborn piglets, we develop an experimental protocol to simulate neonatal asphyxia which has advantages of studying the systemic and regional hemodynamics, oxygen transport with biochemical and pathologic pathways and correlations.

Annually more than 1 million neonates die worldwide as related to asphyxia. Asphyxiated neonates commonly have multi-organ failure including hypotension, ...

Permanent Ligation of the Left Anterior Descending Coronary Artery in Mice: A Model of Post-myocardial Infarction Remodelling and Heart Failure

Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It is characterized by fluid retention, shortness of breath, and fatigue, in particular on exertion. Heart failure is a growing public health problem, the leading cause of hospitalization, and a major cause of mortality. Ischemic heart disease is the main cause of heart failure.
Ventricular remodelling refers to changes in structure, size, and shape of the left ventricle. This architectural remodelling of the left ventricle is induced by injury (e.g., myocardial infarction), by pressure overload (e.g., systemic arterial hypertension or aortic stenosis), or by volume overload. Since ventricular remodelling affects wall stress, it has a profound impact on cardiac function and on the development of heart failure. A model of permanent ligation of the left anterior descending coronary artery in mice is used to investigate ventricular remodelling and cardiac function post-myocardial infarction. This model is fundamentally different in terms of objectives and pathophysiological relevance compared to the model of transient ligation of the left anterior descending coronary artery. In this latter model of ischemia/reperfusion injury, the initial extent of the infarct may be modulated by factors that affect myocardial salvage following reperfusion. In contrast, the infarct area at 24 hr after permanent ligation of the left anterior descending coronary artery is fixed. Cardiac function in this model will be affected by 1) the process of infarct expansion, infarct healing, and scar formation; and 2) the concomitant development of left ventricular dilatation, cardiac hypertrophy, and ventricular remodelling.
Besides the model of permanent ligation of the left anterior descending coronary artery, the technique of invasive hemodynamic measurements in mice is presented in detail.

Heart failure is the leading cause of hospitalization and a major cause of mortality. A model of permanent ligation of the left anterior descending coronary artery in mice is applied to investigate ventricular remodelling and cardiac dysfunction post-myocardial infarction. The technique of invasive hemodynamic measurements in mice is presented.

Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

A Chronic Cardiac Ischemia Model in Swine Using an Ameroid Constrictor

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but regardless of the approach, an in vivo model is needed to test each treatment. The pig is one of the most used large animal models for cardiovascular disease. Its heart is very similar in anatomy and function to that of a human. The ameroid placement technique creates an ischemic area of the heart, which has many useful applications in studying myocardial infarction. This model has been used for surgical research, pharmaceutical studies, imaging techniques, and cell therapies.
There are several ways of inducing an ischemic area in the heart. Each has its advantages and disadvantages, but the placement of an ameroid constrictor remains the most widely used technique. The main advantages to using the ameroid are its prevalence in existing research, its availability in various sizes to accommodate the anatomy and size of the vessel to be constricted, the surgery is a relatively simple procedure, and the post-operative monitoring is minimal, since there are no external devices to maintain. This paper provides a detailed overview of the proper technique for the placement of the ameroid constrictor.

The purpose of this protocol is to demonstrate the placement of a delayed constricting device (an ameroid constrictor) around a coronary artery in a swine model. This device creates an ischemic area of the heart that is useful for studying new diagnostic imaging techniques and new methods of treatment.

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but ...

Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment methods. Here, we present such a model by tachycardia-induced cardiomyopathy, which can be produced by rapid cardiac pacing in swine.
A single pacing lead is introduced transvenously into fully anaesthetized healthy swine, to the apex of the right ventricle, and fixated. Its other end is then tunneled dorsally to the paravertebral region. There, it is connected to an in-house modified heart pacemaker unit that is then implanted in a subcutaneous pocket. 
After 4 - 8 weeks of rapid ventricular pacing at rates of 200 - 240 beats/min, physical examination revealed signs of severe heart failure - tachypnea, spontaneous sinus tachycardia, and fatigue. Echocardiography and X-ray showed dilation of all heart chambers, effusions, and severe systolic dysfunction. These findings correspond well to decompensated dilated cardiomyopathy and are also preserved after the cessation of pacing.
This model of tachycardia-induced cardiomyopathy can be used for studying the pathophysiology of progressive chronic heart failure, especially hemodynamic changes caused by new treatment modalities like mechanical circulatory supports. This methodology is easy to perform and the results are robust and reproducible.

Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment ...

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 ...

Post-Myocardial Infarction Heart Failure in Closed-chest Coronary Occlusion/Reperfusion Model in G&#246;ttingen Minipigs and Landrace Pigs

The development of heart failure is the most powerful predictor of long-term mortality in patients surviving acute myocardial infarction (MI). There is an unmet clinical need for prevention and therapy of post-myocardial infarction heart failure (post-MI HF). Clinically relevant pig models of post-MI HF are prerequisites for final proof-of-concept studies before entering into clinical trials in drug and medical device development.
Here we aimed to characterize a closed-chest porcine model of post-MI HF in adult G&#246;ttingen minipigs with long-term follow-up including serial cardiac magnetic resonance imaging (CMRI) and to compare it with the commonly used Landrace pig model.
MI was induced by intraluminal balloon occlusion of the left anterior descending coronary artery for 120 min in G&#246;ttingen minipigs and for 90 min in Landrace pigs, followed by reperfusion. CMRI was performed to assess cardiac morphology and function at baseline in both breeds and at 3 and 6 months in G&#246;ttingen minipigs and at 2 months in Landrace pigs, respectively.
Scar sizes were comparable in the two breeds, but MI resulted in a significant decrease of left ventricular ejection fraction (LVEF) only in G&#246;ttingen minipigs, while Landrace pigs did not show a reduction of LVEF. Right ventricular (RV) ejection fraction increased in both breeds despite the negligible RV scar sizes. In contrast to the significant increase of left ventricular end-diastolic (LVED) mass in Landrace pigs at 2 months, G&#246;ttingen minipigs showed a slight increase in LVED mass only at 6 months.
In summary, this is the first characterization of post-MI HF in G&#246;ttingen minipigs in comparison to Landrace pigs, showing that the G&#246;ttingen minipig model reflects post-MI HF parameters comparable to the human pathology. We conclude that the G&#246;ttingen minipig model is superior to the Landrace pig model to study the development of post-MI HF.

The overall goal of the current study is to present the techniques of induction of myocardial infarction (MI) and post-myocardial infarction heart failure (post-MI HF) in closed-chest, adult G&#246;ttingen minipigs and the characterization of post-MI HF model in G&#246;ttingen minipigs as compared to Landrace pigs.

The development of heart failure is the most powerful predictor of long-term mortality in patients surviving acute myocardial infarction (MI). There is an ...