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 Figure 1.
1. Surgical procedures
<ol>
	<li>Anesthesia and preparation of the animal
	<ol>
		<li>Fast the animals for 12 h and subject to water deprivation for 4 h before the experiment.</li>
		<li>Anesthetize the pigs through an intramuscular injection of tiletamine+zolezepam (2-7 mg/kg) and xylazine (0.5-1 mg/kg) prepared in 20 mL of normal saline. Monitor the animal&#39;s palpebral reflexes until they are absent.</li>
		<li>Remove the pig&#39;s hair and sterilize the skin at the neck and the groin for sections 1.3-1.5. Disinfect the operation area 3x with 70% ethanol and betadine.</li>
		<li>Place a 7 mm endotracheal tube into the porcine trachea and place a 22 G venous indwelling needle into the ear vena.</li>
		<li>Move the pig onto the operating table and place in a supine position. Connect the endotracheal tube to the respirator and mechanically ventilate (inspiratory/expiratory time ratio 1:2) the animal with isoflurane (1.5%-2.0% inhalation) and oxygen (0.5-1.5 L/min inhalation).</li>
		<li>Monitor the surface electrocardiogram and blood pressure, and continuously monitor the heart rate, heart rhythm, and arterial blood pressure via electrophysiology recording systems.</li>
	</ol>
	</li>
	<li>Echocardiography
	<ol>
		<li>Move the pig to the left lateral decubitus position and fix on the table.</li>
		<li>Put the probe on the pericardial region and perform serial echocardiography, including 2D and M-mode imaging, using a high-resolution echocardiographic system and a 3-9 MHz transducer at the baseline, before cell transplantation and 8 weeks after cell transplantation (Supplemental Figure 1).</li>
		<li>Analyze all the obtained images using commercial software. Calculate the LV end-diastolic dimension (LVEDD), LV end-systolic dimension (LVESD), LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LV ejection fraction (LVEF), and wall thickness after standard echocardiographic images are obtained from the parasternal long-axis view. 
		NOTE: All the off-line analyses were conducted by another independent operator using a computer workstation. The variability of the measurements between different observers was 4% based on 20 repeated random images. All the echocardiographic measurements were performed in accordance with the American Society of Echocardiography recommendations.</li>
	</ol>
	</li>
	<li>Pacemaker implantation
	<ol>
		<li>Move the pig to the supine position and fix the limbs of the pig on the table with straps.</li>
		<li>Locate the right carotid artery and jugular vein in the carotid triangle (behind the sternocleidomastoid and surrounded by the stylohyoid, the digastric muscle, and the omohyoid) and isolate the right carotid artery and jugular vein with hemostatic forceps under sterile conditions (Supplemental Figure 2). Ligate the distal end of the right carotid artery and jugular vein.&#160;Sew the two muscles with 2-0 Vicryl. </li>
		<li>Cannulate the right jugular vein with an angiocath and insert a pacemaker lead to the right ventricle under X-ray guidance (Figure 2).</li>
		<li>Isolate the sternocleidomastoid and the anterior scalene muscle using forceps. Implant a pacemaker between the two muscles and sew the two muscles with 2-0 silk. Connect the pacemaker to the lead.</li>
		<li>Reprogram the pacemaker to backup VVI mode (35 bpm) by a pacemaker generator after the transplantation.</li>
		<li>Apply rapid ventricular pacing (150 beats/min) to induce HF by a pacemaker generator 4 weeks after MI induction. Then set the pacemaker back to backup VVI mode at 8 weeks.</li>
	</ol>
	</li>
	<li>Invasive pressure volume loop analysis 
	NOTE: Perform invasive hemodynamic assessment at baseline, before cell transplantation and 8 weeks after cell transplantation to assess changes in LV function.
	<ol>
		<li>Isolate the right femoral artery and femoral vein in the femoral triangle (surrounded by the inguinal ligament, sartorius muscle, and adductor longus muscle) (Supplemental Figure 2).</li>
		<li>Cannulate the right femoral artery with an angiocath and place a guidewire into the artery via the angiocath. Remove the angiocath and cannulate a 9F sheath into the artery under the guidance of the guidewire. Remove the guidewire.</li>
		<li>Cannulate the right femoral vein with a 12F sheath as described in step 1.4.2. Insert a balloon catheter from the placed 12F sheath into the inferior vena cava (IVC) under X-ray guidance.</li>
		<li>Calibrate a 7 Fr pressure-volume (PV) catheter in isotonic saline with a PV signal processor.</li>
		<li>Insert the PV catheter into the LV apex from the placed 9F sheath under X-ray guidance. Suspend ventilation and measure the left ventricular maximal positive pressure derivative (+dP/dt), end-systolic pressure (ESP), and end-diastolic pressures (EDP) with the PV signal processor.</li>
		<li>Measure the end systolic pressure-volume relationship (ESPVR) by the PV signal processor during the occlusion of the IVC.</li>
		<li>Restart ventilation when the procedure is finished.</li>
	</ol>
	</li>
	<li>Induction of MI
	<ol>
		<li>Intravenously administer amiodarone (5 mg/kg intravenously over 1 h) and lidocaine (1.5 mg/kg intravenous bolus) to the animal before induction of MI to prevent ventricular arrhythmias.</li>
		<li>Cannulate the right carotid artery with an 8F sheath as mentioned in step 1.4.3.</li>
		<li>Perform the coronary angiography through a 6F JR4 over-the-wire guiding catheter via the placed sheath guided by standard C arm fluoroscopy equipment.</li>
		<li>Occlude the left circumflex coronary artery (LCX) distal to the first obtuse marginal branch with percutaneous transluminal coronary angioplasty (PTCA) dilatation balloon catheter inflation under X-ray guidance (Figure 2).</li>
		<li>Inject 1 mL of 700 &#181;m sponge microspheres mixed with 3&#160;mL of saline prepared in a 10 mL syringe through the balloon catheter to block the LCX, then deflate the balloon and perform an angiogram to confirm the occlusion.</li>
		<li>Repeat the injection procedure to achieve successful complete blockage.</li>
		<li>Monitor the animal heart rate and rhythm to detect cardiac arrhythmias. If ventricular fibrillation happened, use an external, biphasic defibrillator to reestablish a sinus rhythm using 150-300 J shocks.</li>
	</ol>
	</li>
	<li>Stem cell injection
	<ol>
		<li>Randomly assign all the animals with notable impairment of heart function (LVEF &#60; 40% at 8 weeks after induction of MI) to two different groups: one that will receive intramyocardial administration of 2 x 108 human induced pluripotent stem cell-derived mesenchymal stem cells (hiPSC-MSCs), and the other that will not receive hiPSC-MSCs.</li>
		<li>Prepare the hiPSC-MSCs in 2 mL of normal saline for intramyocardial transplantation. Before intramyocardial hiPSC-MSCs transplantation, repeat the anesthesia and animal preparation steps mentioned in section 1.1, this time sterilizing 10 cm around the apex beat area. Perform left thoracotomy at the 4-5 intercostal space with a retractor. Perform pericardiotomy to expose the infarcted lateral wall. 
		NOTE: The length of the incision was 10-12 cm.</li>
		<li>Use 5-8 intramyocardial injections (~0.3 mL per injection) around the infarcted area to administer culture medium (Table of Materials)&#160;to one group of animals or 2 x 108 hiPSC-MSCs to the other group (Figure 3). Carefully avoid any damage to coronary arteries to reduce the risk of hemorrhage.</li>
		<li>Close the intercostal space with iron wire and close the muscle layer with 2-0 silk. Sew the subcutaneous tissue and skin with 2-0 vicryl.</li>
	</ol>
	</li>
	<li>Intracardiac programmed electrical stimulation
	<ol>
		<li>Perform programmed electrical stimulation using a programmable stimulator to assess the inducibility of ventricular tachyarrhythmia (VT) after the cell transplantation therapy.</li>
		<li>Insert a 6F electrophysiological catheter into the right ventricular apex via the femoral vein before sacrificing all the animals.</li>
		<li>Display the intracardiac recordings with the surface electrocardiogram leads I, II, and III on the electrophysiological recording system at a speed of 200 mm/s. Deliver a 2 ms pulse width at 2x the diastolic threshold using a stimulator.</li>
		<li>Deliver a pacing train of eight stimuli (S1) at two drive cycle lengths (200 ms and 300 ms), followed by one (S2) or two (S2 and S3) premature extra stimuli.</li>
		<li>Sequentially shorten the coupling intervals until a ventricular effective refractory period or arrhythmia is induced. Note the presence of inducible sustained VT (&#62;10 s).</li>
	</ol>
	</li>
</ol>
2. Postoperative protocol
<ol>
	<li>Postoperative medicine
	<ol>
		<li>Perform conventional pharmacological therapies for HF. In brief, orally administer metoprolol succinate (25 mg) and ramipril (2.5 mg) to all animals daily.</li>
		<li>Intramuscularly administer enrofloxacin (5 mg/kg) and buprenorphine (0.01 mg/kg) to all animals daily for 1 week after surgery to prevent infection and relieve pain.</li>
		<li>To minimize immunological rejection, orally administer a steroid (40 mg/day orally) and cyclosporine (200 mg/day orally) to all animals from 3 days prior to cell transplantation to 8 weeks after.</li>
	</ol>
	</li>
	<li>Infarct size assessment
	<ol>
		<li>Euthanize the animals by an overdose of dorminal (pentobarbital sodium, 100 mg/kg, IV) at the end of the experiment.</li>
		<li>Open the chest and collect the heart. Rinse the heart in 0.9% saline.</li>
		<li>Serially section LV tissue samples with a scalpel at 1 cm thicknesses in the LV transverse direction.</li>
		<li>Select portions of the slices that contain the infarcted myocardium to measure the wall thickness and the infarct area.</li>
		<li>Capture the image of these slices and quantitatively analyze the wall thickness and the infarct area using commercial image analysis software.</li>
		<li>Fix the tissue in 10% formalin at 4 &#176;C for a month. Embed the tissue within, adjacent and remote to the infarct sites (~1 cm2 pieces) in paraffin. Section into 5 &#181;m slices using a microtome for histological examination.</li>
	</ol>
	</li>
	<li>Cell survival
	<ol>
		<li>Detect the engraftment of the transplanted cells by immunohistochemical staining with anti-human nuclear antigen (HNA) according to the protocol provided by the manufacturer.</li>
		<li>Capture the image in three different sections at five random fields in each animal and quantitatively analyze the positive cells in the peri-infarct zone. 
		NOTE: The image capturing system and image analysis software were used to capture and analyze the images of the heart sections.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

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 ...

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6.6K Views.  University of Hong Kong. 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.

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

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 ...

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 ...

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.

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