This work was funded by grants from the National Health and Medical Research Council APP1194139/APP1126276 (JC), National Stem Cell Foundation of Australia and New South Wales Government Office of Health and Medical Research (JC). DS was supported by the Royal Australasian College of Physicians, the Institute of Clinical Pathology and Medical Research, and the Australian Government Research Training Program. TD was supported by the Institute of Clinical Pathology and Medical Research, Penfolds Family Scholarship, National Health and Medical Research Council (APP2002783) and the National Heart Foundation of Australia (104615).

<ol>
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The authors have nothing to disclose.

Transepicardial intramyocardial injection 
This procedure has the benefit of direct cardiac visualization and has been demonstrated to provide greater local retention of therapeutics than systemic administration methods9,10,14. However, thoracotomies are invasive, require considerable technical skill, and present a greater risk of morbidity and mortality than other methods discussed10,15. Knowledge of the critical and precarious stages of the procedure can assist in the mediation of this increased risk.
Great care must be exercised upon manipulating the heart to expose the cardiac apex due to the high risk of arrhythmia and associated hemodynamic compromise. Continuous invasive blood pressure monitoring and electrocardiography allow for rapid identification of hypotension or unstable arrhythmias, facilitating prompt intervention and correction. Transient hypotension can generally be treated with metaraminol boluses. Sustained hypotension may be temporized by reducing inhalant anaesthetic (careful monitoring of anaesthetic depth) and commencing a vasopressor infusion, while concurrently determining the cause of altered hemodynamics. Unstable arrhythmias, such as ventricular tachycardia or ventricular fibrillation, can be treated by electrical cardioversion with or without intravenous antiarrhythmics.
Equally important for animal survival is the successful removal of free gas from the pleural cavity before closing the chest. Failure to do so can culminate in developing a pneumothorax, leaving the animal at great risk of respiratory compromise and death once disconnected from the mechanical ventilator at recovery. Positive airway pressure must be maintained for at least 30 s until bubbling is no longer observed. The silicone tubing is promptly removed upon the cessation of bubbling, and the thorax is then rapidly closed. It is also possible to surgically place a thoracostomy tube at closure, allowing manual air and inflammatory fluid removal over the next 24-72 h. This, however, is difficult to keep clean and intact, especially if animals are housed together. Damage or contamination of the tube can lead to pyothorax, pneumothorax, or sepsis. In our experience, inserting a temporary chest drain is not required if free gas is adequately removed prior to chest closure.
Percutaneous transendocardial intramyocardial injection 
This method of therapeutic administration has the benefit of allowing for local tissue delivery with lower risk due to its less invasive nature compared with a surgical approach10,14. This technique is already used in large animal studies, with both fluoroscopy and electromechanical mapping as a guide in the absence of direct visualization10,16,17.
Given the heart isn&#39;t under direct vision, it is prudent for the proceduralist to use orthogonal fluoroscopic views when selecting an injection site. Furthermore, the injection of diluted iodine contrast before and delivery of the therapeutic is extremely valuable in confirming myocardial contact. Appropriate contact can be confirmed by observing a characteristic &#39;myocardial blush&#39;, which may be one of the only markers of injection success prior to tissue harvest. Due to the risk of chamber perforation, the myocardial wall thickness at the selected injection site is also recommended to be greater than 9 mm14,16.
Jugular venous osmotic minipump 
The osmotic minipump is a popular device commonly employed in small animal studies. There has been increasing interest in using this device in large animal models7,18,19, given its unique advantage of administering a therapeutic agent at a consistent rate over a set time period. A possible limitation of this method is the inability to alter or stop infusion rates of the drug without replacing or removing the pump. This should be considered before trialing therapy in this manner.
This study demonstrated that this method could be performed with a high success rate in swine, with low morbidity and mortality. It must be noted that many vital structures are adjacent to the surgical site, including lymph nodes, the thymus, and the carotid artery. Adherence to the method, and consultation of anatomical texts20, are strongly recommended to prevent inadvertent damage to any of these structures. The most concerning complication of this method is hemorrhagic shock due to inadvertent injury to the jugular vein or a surrounding structure. It is therefore critical that the soft tissue surrounding the jugular vein is carefully removed. Failure to properly complete this step can lead to difficulty in placing the minipump tubing or controlling inadvertent bleeding.
This article has described three methods for the delivery of cardioactive therapeutics. Despite the reported success of each technique, there are inherent limitations to be considered. Invasive procedures (transepicardial injection) allow for increased accuracy of therapeutic delivery; however, they bring a greater risk of potentially fatal complications. Furthermore, invasive delivery has a greater requirement for technical skills to minimize the risk of complications. Similarly, fluoroscopic-guided, transendocardial injection requires a degree of technical skill for catheterization and manipulation of hardware. If this method is performed improperly, injection failure and fatal complications are possible.
The direct injection methods described allow for the one-off administration of a therapeutic into the target tissue. The jugular venous osmotic minipump allows for the systemic administration of a therapeutic over a 7 day period. Comparatively, this method is simpler and associated with less risk, however, it relies on a systemic therapeutic finding its way to the myocardium. Additionally, once the pump is in place, it is impossible to discontinue administration or alter the dose rate without re-anaesthetizing the animal and removing the pump.
All methods described in this article were performed on animals on the day or 2 weeks after myocardial infarction. Therefore, this work cannot report the success of mentioned methods in healthy animals or animals subjected to an alternative cardiac pathology. Finally, the pharmacology and biotechnology of any intended agent are to be carefully considered, as this will be inherently linked to the efficacy of the chosen delivery route. A detailed discussion of this is beyond the scope of this manuscript.
Comprehensive depictions of preclinical methods benefit animal welfare and the wider scientific community. The resultant enhanced reproducibility of procedures and results leads to fewer animal health complications, reduced number of animals required to produce significant results, and greater confidence in experimental outcomes21,22. Three methods of administration of novel therapeutics are described in this article for the treatment of myocardial infarction in a porcine model. By detailing the techniques used and articulating the benefits and risks of each, it is anticipated that researchers will be able to comfortably create consistent and reliable preclinical models that suit their research goals.

Coronary artery disease (CAD) and associated ST-elevation myocardial infarction (STEMI) are the preeminent causes of death worldwide. In the past two decades, great progress has been made in reducing in-hospital mortality of patients presenting with STEMI, through the advent of percutaneous coronary intervention, fibrinolytic therapies, and standardization of treatment algorithms to ensure that reperfusion is achieved in a timely manner1,2,3. Despite this, the morbidity associated with STEMI remains a significant burden, thus creating a great need for developing novel cardioprotective and regenerative therapies2,3. An essential component of therapeutic development is the determination of how a novel therapy is to be administered4. The safety, efficacy, and feasibility of each method need to be matched with the characteristics of the therapy itself.
Physiologically relevant large animal models are critical in assessing these attributes of various therapeutic delivery strategies5. Due to their similarities to humans in cardiovascular physiology, coronary vascular anatomy, and heart weight to body weight ratio, swine is one of the preferred species in the preclinical evaluation of new therapies for myocardial infarction6. We have previously used a porcine STEMI model to demonstrate the reparative capacity of a recombinant protein therapy7, and continue to investigate novel pharmacologic, cellular, and genetic therapies using this model. Here, three techniques of therapeutic administration used in swine models after infarct creation are described: thoracotomy and transepicardial injection, percutaneous transendocardial injection, and jugular venous osmotic minipump implantation. The first two methods enable local tissue delivery, reducing required dosages, off-target effects, and hepatic first-pass metabolism8,9,10. The osmotic minipump allows continuous delivery of a drug with a short half-life, negating reliance on an infusion pump and patent intravenous cannula, both of which are challenging to institute in large animal models.
By describing these techniques, it is hoped that this article can aid translational scientists in investigating novel cardioprotective or regenerative agents following myocardial infarction in large animal models.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Central line placement</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2-0 sutures</td>
			<td>Ethicon</td>
			<td>JJ9220</td>
			<td></td>
		</tr>
		<tr>
			<td>Arrow&#39; Paediatric Two-Lumen Central Venous Catheterisation Set with Blue FlexTip Catheter (contains 18G cook needle and 0.035&#34; J-tip wire)</td>
			<td>Teleflex</td>
			<td>CS-14502</td>
			<td>Central Line</td>
		</tr>
		<tr>
			<td>Green Fluorsence Protein (GFP)</td>
			<td>Abcam</td>
			<td>ab13970</td>
			<td>1:100 dilution ratio</td>
		</tr>
		<tr>
			<td>Histology antibodies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ku80</td>
			<td>Cell Signalling Technology</td>
			<td>C48E7</td>
			<td>1:500 dilution ratio</td>
		</tr>
		<tr>
			<td>No. 11 scalpel</td>
			<td>Swann-Morton</td>
			<td>203</td>
			<td></td>
		</tr>
		<tr>
			<td>Sparq&#39; Ultrasound System</td>
			<td>Philips</td>
			<td>MP11742 Medpick</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile ultrasound probe cover</td>
			<td>Atris</td>
			<td>28041947</td>
			<td></td>
		</tr>
		<tr>
			<td>Swine Jacket with Pocket, size &#39;Medium&#39;</td>
			<td>Lomir Biomedical</td>
			<td>SS J2YJJET</td>
			<td></td>
		</tr>
		<tr>
			<td>Jugular vein osmotic minipump implantation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adson Brown Tissue Forceps</td>
			<td>Icon Medical Supplies</td>
			<td>KLINI316012</td>
			<td></td>
		</tr>
		<tr>
			<td>Bellucci Self-Retaining Retractor</td>
			<td>surgicalinstruments.net.au</td>
			<td>group-24.26.02</td>
			<td>Self retaining tissue retractor</td>
		</tr>
		<tr>
			<td>Electrosurgical Pencils with &#39;Edge&#39; Coated Electrodes</td>
			<td>Covidien</td>
			<td>E2450H</td>
			<td>Cautery Pencil</td>
		</tr>
		<tr>
			<td>Metzenbaum Scissors</td>
			<td>Icon Medical Supplies</td>
			<td>ARMO3250</td>
			<td></td>
		</tr>
		<tr>
			<td>No. 22 scalpel blade</td>
			<td>Swann-Morton</td>
			<td>208</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon Suture&#160; (2-0, 3-0)</td>
			<td>Ethicon</td>
			<td>D9635, 663G</td>
			<td></td>
		</tr>
		<tr>
			<td>Osmotic Infusion Minipump</td>
			<td>Alzet</td>
			<td>2ML1, 2ML2, 2ML4</td>
			<td></td>
		</tr>
		<tr>
			<td>Vascular Silicone Ties</td>
			<td>Vecmedical</td>
			<td>95001</td>
			<td></td>
		</tr>
		<tr>
			<td>Vicryl suture (5-0)</td>
			<td>Ethicon</td>
			<td>W9982</td>
			<td></td>
		</tr>
		<tr>
			<td>Percutaneous transedocardial injection</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Artis Zee&#39; C-Arm Fluoroscopy&#160;</td>
			<td>Siemens&#160;</td>
			<td>IR-19-1994</td>
			<td></td>
		</tr>
		<tr>
			<td>CARTO&#39; 3 System&#160;&#160;</td>
			<td>Biosense Webster</td>
			<td></td>
			<td>Electrophysiological Mapping Software &#38; System</td>
		</tr>
		<tr>
			<td>Cook Access Needle</td>
			<td>Cook Medical</td>
			<td>G07174</td>
			<td>Cannulation needle</td>
		</tr>
		<tr>
			<td>Fast-Cath&#39; Introducer (6 French, 8 French)</td>
			<td>Abbott</td>
			<td>406204, 406142</td>
			<td>Vascular sheath with introducer and guidewire</td>
		</tr>
		<tr>
			<td>Myostar&#39; Injection Catheter</td>
			<td>Biosense Webster</td>
			<td>121117S, 121119S, 1211120S</td>
			<td>Intramyocardial injection catheter</td>
		</tr>
		<tr>
			<td>No.11 scalpel</td>
			<td>Swann-Morton</td>
			<td>203</td>
			<td></td>
		</tr>
		<tr>
			<td>Omnipaque&#39; Iohexol Contrast</td>
			<td>GE Healthcare</td>
			<td>AUST R 39861&#160;</td>
			<td>Iodinated contrast agent</td>
		</tr>
		<tr>
			<td>Sparq&#39; Ultrasound System</td>
			<td>Philips</td>
			<td>MP11742 Medpick</td>
			<td></td>
		</tr>
		<tr>
			<td>Sedation &#38; general anaesthesia</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Compound Sodium Lactate Hartmann&#39;s Solution</td>
			<td>Free flex</td>
			<td>894451</td>
			<td></td>
		</tr>
		<tr>
			<td>Fentanyl 50 mcg/mL</td>
			<td>Pfizer</td>
			<td>AUST R 107027.</td>
			<td>Intravenous anaesthesia and analgesia</td>
		</tr>
		<tr>
			<td>Forthane&#39; Isoflurane</td>
			<td>Abbott</td>
			<td>AUST R 29656&#160;</td>
			<td>Inhalant anaesthetic</td>
		</tr>
		<tr>
			<td>GE Aestiva 5 Anaesthesia Machine&#160;</td>
			<td>Datex Ohmeda</td>
			<td>17002-9, 17002A9 Avante Health Solutions</td>
			<td>Anaesthetic Machine&#160;</td>
		</tr>
		<tr>
			<td>Hypnovel&#39; Midazolam 5 mg/mL</td>
			<td>Roche</td>
			<td>AUST R 13726</td>
			<td>Sedative</td>
		</tr>
		<tr>
			<td>Intravenous cannula</td>
			<td>BD Angiocath</td>
			<td>381137</td>
			<td>20 gauge cannula</td>
		</tr>
		<tr>
			<td>Ketamil&#39; Ketamine 10 mg/mL</td>
			<td>Ilium</td>
			<td>APVMA number: 51188c&#160;</td>
			<td>Sedative</td>
		</tr>
		<tr>
			<td>Laryngoscope</td>
			<td>Miller</td>
			<td>VDI-6205</td>
			<td></td>
		</tr>
		<tr>
			<td>Medetomidine 1 mg/mL</td>
			<td>Ilium</td>
			<td>APVMA number 64251; ACVM number A10488&#160;</td>
			<td>Sedative</td>
		</tr>
		<tr>
			<td>Metaraminol 10 mg/mL</td>
			<td>Phebra</td>
			<td>AUST R 284784</td>
			<td>Short-acting vasopressor</td>
		</tr>
		<tr>
			<td>Methadone 10 mg/mL</td>
			<td>Ilium</td>
			<td>APVMA number: 63712&#160;</td>
			<td>Sedative, Restricted drug</td>
		</tr>
		<tr>
			<td>Onsetron&#39; Ondansetron 2 mg/mL</td>
			<td>Accord Healthcare</td>
			<td>AUST R 205593&#160;</td>
			<td>Anti-emetic</td>
		</tr>
		<tr>
			<td>Propofol-Lipuro&#39; Propofol 10 mg/mL</td>
			<td>Braun</td>
			<td>AUST R 142906&#160;</td>
			<td>Intravenous anaesthetic</td>
		</tr>
		<tr>
			<td>Pulse Oximeter&#160;</td>
			<td>Meditech</td>
			<td>GVPMT-M3S</td>
			<td>Portable pulse oximeter</td>
		</tr>
		<tr>
			<td>Shiley&#39; Cuffed Basic Endotracheal Tube (Size 5.5 &#38; 6.0)</td>
			<td>Medtronic</td>
			<td>86108-, 86109-</td>
			<td></td>
		</tr>
		<tr>
			<td>Shiley&#39; Intubating Stylet, 10 Fr</td>
			<td>Medtronic</td>
			<td>85864</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride 0.9%</td>
			<td>Free flex</td>
			<td>FAH1322</td>
			<td></td>
		</tr>
		<tr>
			<td>Thoracotomy and epicardial Cell Injection</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>27 G Insulin needle</td>
			<td>Terumo</td>
			<td>51907</td>
			<td></td>
		</tr>
		<tr>
			<td>Adson Brown Tissue Forceps</td>
			<td>Icon Medical Supplies</td>
			<td>KLINI316012</td>
			<td></td>
		</tr>
		<tr>
			<td>CARTO&#39; 3 System&#160;&#160;</td>
			<td>Biosense Webster</td>
			<td></td>
			<td>Electrophysiological Mapping Software &#38; System</td>
		</tr>
		<tr>
			<td>Cefazolin 1 g Vial</td>
			<td>AFT Pharmaceuticals</td>
			<td>9421900137367 CH2</td>
			<td>Antibiotic Prophylaxis&#160;</td>
		</tr>
		<tr>
			<td>Chest drainage tube</td>
			<td>SurgiVet</td>
			<td>SKU-336</td>
			<td></td>
		</tr>
		<tr>
			<td>Cook Access Needle</td>
			<td>Cook Medical</td>
			<td>G07174</td>
			<td>Cannulation needle</td>
		</tr>
		<tr>
			<td>Cooley Sternotomy Retractor Paediatric</td>
			<td>Millennium Surgical</td>
			<td>9-61287</td>
			<td></td>
		</tr>
		<tr>
			<td>Durogesic&#39; 100 mcg/h Fentanyl Patch</td>
			<td>Janssen</td>
			<td>AUST R 112371&#160;</td>
			<td>Postoperative analgesia</td>
		</tr>
		<tr>
			<td>Electrosurgical Pencils with &#39;Edge&#39; Coated Electrodes</td>
			<td>Covidien</td>
			<td>E2450H</td>
			<td>Cautery Pencil</td>
		</tr>
		<tr>
			<td>Electrosurgical Pencils with &#39;Edge&#39; Coated Electrodes</td>
			<td>Covidien</td>
			<td>E2450H</td>
			<td>Cautery Pencil</td>
		</tr>
		<tr>
			<td>Fast-Cath&#39; Introducer (6 French, 8 French)</td>
			<td>Abbott</td>
			<td>406204, 406142</td>
			<td>Vascular sheath with introducer and guidewire</td>
		</tr>
		<tr>
			<td>Lignocaine 20 mg/mL</td>
			<td>Pfizer</td>
			<td>AUST R 49296, AUST R 49297, AUST R 49293 and AUST R 49295.</td>
			<td>Local anaesthesia, anti-arrhythmic</td>
		</tr>
		<tr>
			<td>Marcaine&#39; Bupivacaine 0.5%</td>
			<td>Pfizer</td>
			<td>AUST R 48328&#160;</td>
			<td>Local anaesthesia.&#160;</td>
		</tr>
		<tr>
			<td>Metzenbaum Scissors</td>
			<td>Icon Medical Supplies</td>
			<td>ARMO3250</td>
			<td></td>
		</tr>
		<tr>
			<td>No. 22 scalpel</td>
			<td>Swann-Morton</td>
			<td>208</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon Suture&#160; (2-0, 3-0)</td>
			<td>Ethicon</td>
			<td>D9635, JJ76264</td>
			<td></td>
		</tr>
		<tr>
			<td>Size 1 PDS suture</td>
			<td>Ethicon</td>
			<td>JJ75414</td>
			<td></td>
		</tr>
		<tr>
			<td>Sparq&#39; Ultrasound System</td>
			<td>Philips</td>
			<td>MP11742 Medpick</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile gauze</td>
			<td>Kerlix</td>
			<td>KE5072</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile laparotomy sponges</td>
			<td>Propax</td>
			<td>2907950</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermocool Smartouch&#39; Catheter</td>
			<td>Biosense Webster</td>
			<td>D133601, D133602, D133603</td>
			<td>Epicardial Mapping Catheter</td>
		</tr>
	</tbody>
</table>

delivery of cardioactive therapeutics in a porcine myocardial infarction model

Myocardial infarction is one of the leading causes of death and disability worldwide, and there is an urgent need for novel cardioprotective or regenerative strategies. An essential component of drug development is determining how a novel therapeutic is to be administered. Physiologically relevant large animal models are of critical importance in assessing the feasibility and efficacy of various therapeutic delivery strategies. Due to their similarities to humans in cardiovascular physiology, coronary vascular anatomy, and heart weight to body weight ratio, swine is one of the preferred species in the preclinical evaluation of new therapies for myocardial infarction. The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. After percutaneously induced myocardial infarction, female landrace swine received treatment with novel agents through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump. The procedures employed for each technique are reproducible, resulting in reliable cardioactive drug delivery. These models can be easily adapted to suit individual study designs, and each of these delivery techniques can be used to investigate a variety of possible interventions. Therefore, these methods are a useful tool for translational scientists pursuing novel biological approaches in cardiac repair following myocardial infarction.

Thoracotomy and epicardial cell injection 
Of the 29 animals that underwent thoracotomy and epicardial injection, 26 survived. Histological analysis confirmed the engraftment of human cells delivered by this method in all surviving animals (Figure 1E). One animal experienced fatal arrhythmias during cell injection and could not be resuscitated. Another experienced pulseless electrical activity during closure and prolonged application of positive pressure to the airways and was unable to be recovered. A third animal both vomited and went into respiratory arrest upon extubation. This animal was unable to be resuscitated.
Two animals experienced major complications but were able to be recovered. One animal developed ventricular fibrillation during intramyocardial injection and was able to be resuscitated with internal defibrillation paddles and cardiac massage. The second animal vomited upon extubation and had a brief respiratory arrest but was able to be rapidly re-intubated and recovered well. All of these events occurred during early experiments, with reduced adverse events as team experience with the protocol increased (Table 1).
Jugular vein osmotic minipump implantation 
No reported mortality or major complications were associated with jugular osmotic minipump implantation. Most of the seven animals experienced mild swelling at the surgical site within the first 24 h, which resolved without intervention. ELISA performed on serum on day 3 post-pump implantation demonstrated the efficacy of the pump, achieving a significant blood concentration of platelet-derived growth factor-AB human (PDGF-AB) compared to controls7 (Figure 2E).
Percutaneous transendocardial injection 
A total of 22 animals received endocardial injections. Of these injections, 17 were considered &#39;successful&#39;, determined by fluorescence or ink staining observed in the target tissue at post-mortem (Figure 3B). There were no mortalities associated with this procedure. One animal developed a small volume pericardial effusion from right ventricular perforation. This was self-limiting and did not result in cardiovascular compromise. This same animal did die; however, this was from an unrelated additional procedure after the intramyocardial injection.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64177/64177fig01.jpg" /> 
Figure 1:&#160;Transepicardial cardiomyocyte injection allows for direct cardiac visualization and achieves a high proportion of viable cells delivered to the myocardium. (A) The cardiac apex is exposed through a moistened gauze sling guided under the base of the heart. (B) An epicardial mapping catheter delineates scar and border zones and annotates injection sites. (C) A 31 G needle is used to transepicardially inject cells into the myocardium. (D) Epicardial voltage map with injection site annotation. Purple: normal voltage, healthy myocardium; Red: abnormal voltage, diseased myocardium; Grey dots: injection sites. Following sacrifice, the heart is collected and formalin-fixed for downstream histological assessment. In (E), engrafted human cells are detected by immunostaining for the human anti-nuclear antibody, Ku80, and an anti-GFP antibody. Scale bar = 200 &#181;m. <a href="https://www.jove.com/files/ftp_upload/64177/64177fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/64177/64177fig02.jpg" /> 
Figure 2: Jugular vein minipump insertion provides a safe and reliable method of PDGF delivery over a 7 day time period. (A) The right jugular vein is exposed, and soft tissue is cleared away from the vessel. (B) Vascular ties occlude the vessel while a 14 G needle is used to make a puncture, through which the minipump tubing is threaded. (C) The minipump tubing is advanced into the vein, and the minipump body is secured to adjacent soft tissue. (D) The minipump body and tubing prior to implantation. (E) The serum concentration of the recombinant protein delivered via the minipump and the PDGF-AB was measured using ELISA from each animal on day 3 post-implantation. Animals receiving PDGF-AB were demonstrated to have a significantly higher blood concentration of PDGF-AB than control animals, confirming the efficacy of the osmotic minipump administration method. **denotes a statistically significant difference between groups (p = 0.005, Mann-Whitney U test) <a href="https://www.jove.com/files/ftp_upload/64177/64177fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/64177/64177fig03.jpg" /> 
Figure 3:&#160;Transendocardial intramyocardial injection allows for a minimally-invasive therapeutics administration method. (A) A right anterior oblique fluoroscopic image demonstrating the injection catheter (white arrow) administering contrast material (yellow arrow) into the myocardium. The contrast material injection both precedes and follows therapeutic injection so that needle placement within the myocardium can be confirmed. (B) The injected vector expressed green fluorescent protein (GFP) so that injected material would fluoresce upon tissue collection, thus confirming the success of the injection. <a href="https://www.jove.com/files/ftp_upload/64177/64177fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td></td>
			<td>Transepicardial Injection (n = 29)</td>
			<td>Transendocardial Injection (n = 22)</td>
			<td>Osmotic Minipump (n = 7)</td>
		</tr>
		<tr>
			<td>Mortality&#160;</td>
			<td>3</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Post-operative vomiting and respiratory arrest</td>
			<td>1</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Ventricular Fibrillation during injection</td>
			<td>1</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Pulseless electrical activity during chest closure</td>
			<td>1</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Morbidity</td>
			<td>0</td>
			<td>1</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Pneumothorax</td>
			<td>0</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Pleural effusion</td>
			<td>0</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Cardiac chamber perforation</td>
			<td>0</td>
			<td>1</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Hemorrhage</td>
			<td>0</td>
			<td>0</td>
			<td>0</td>
		</tr>
	</tbody>
</table>
Table 1:&#160;Complications list.

Watch this Scientific Journal Video about Delivery of Cardioactive Therapeutics in a Porcine Myocardial Infarction Model at JoVE.com

Delivery of Cardioactive Therapeutics in a Porcine Myocardial Infarction Model

The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. Female landrace swine received treatment through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump.

Myocardial infarction is one of the leading causes of death and disability worldwide, and there is an urgent need for novel cardioprotective or ...

delivery-cardioactive-therapeutics-porcine-myocardial-infarction

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1.1K Views.  The University of Sydney. The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. Female landrace swine received treatment through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump.

Video: Delivery of Cardioactive Therapeutics in a Porcine Myocardial Infarction Model

Acute Myocardial Infarction in Rats

With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular diseases. Animal models that mimic human cardiac disease, such as myocardial infarction (MI) and ischemia-reperfusion (IR) that induces heart failure as well as pressure-overload (transverse aortic constriction) that induces cardiac hypertrophy and heart failure (Goldman and Tarnavski), are useful models to study cardiovascular disease. In particular, myocardial ischemia (MI) is a leading cause for cardiovascular morbidity and mortality despite controlling certain risk factors such as arteriosclerosis and treatments via surgical intervention (Thygesen). Furthermore, an acute loss of the myocardium following myocardial ischemia (MI) results in increased loading conditions that induces ventricular remodeling of the infarcted border zone and the remote non-infarcted myocardium. Myocyte apoptosis, necrosis and the resultant increased hemodynamic load activate multiple biochemical intracellular signaling that initiates LV dilatation, hypertrophy, ventricular shape distortion, and collagen scar formation. This pathological remodeling and failure to normalize the increased wall stresses results in progressive dilatation, recruitment of the border zone myocardium into the scar, and eventually deterioration in myocardial contractile function (i.e. heart failure). The progression of LV dysfunction and heart failure in rats is similar to that observed in patients who sustain a large myocardial infarction, survive and subsequently develops heart failure (Goldman). The acute myocardial infarction (AMI) model in rats has been used to mimic human cardiovascular disease; specifically used to study cardiac signaling mechanisms associated with heart failure as well as to assess the contribution of therapeutic strategies for the treatment of heart failure. The method described in this report is the rat model of acute myocardial infarction (AMI). This model is also referred to as an acute ischemic cardiomyopathy or ischemia followed by reperfusion (IR); which is induced by an acute 30-minute period of ischemia by ligation of the left anterior descending artery (LAD) followed by reperfusion of the tissue by releasing the LAD ligation (Vasilyev and McConnell). This protocol will focus on assessment of the infarct size and the area-at-risk (AAR) by Evan's blue dye and triphenyl tetrazolium chloride (TTC) following 4-hours of reperfusion; additional comments toward the evaluation of cardiac function and remodeling by modifying the duration of reperfusion, is also presented. Overall, this AMI rat animal model is useful for studying the consequence of a myocardial infarction on cardiac pathophysiological and physiological function.

The rat model of acute myocardial infarction (AMI) is useful to study the consequence of a MI on cardiac pathophysiological and physiological function.

With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular ...

MRI and PET in Mouse Models of Myocardial Infarction

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ideal model for testing novel therapeutic strategies.
In vivo magnetic resonance imaging (MRI) gives excellent views of the heart noninvasively with clear anatomical detail, which can be used for accurate functional assessment. Contrast agents can provide basic measures of tissue viability but these are nonspecific. Positron emission tomography (PET) is a complementary technique that is highly specific for molecular imaging, but lacks the anatomical detail of MRI. Used together, these techniques offer a sensitive, specific and quantitative tool for the assessment of the heart in disease and recovery following treatment.
In this paper we explain how these methods are carried out in mouse models of acute myocardial infarction. The procedures described here were designed for the assessment of putative protective drug treatments. We used MRI to measure systolic function and infarct size with late gadolinium enhancement, and PET with fluorodeoxyglucose (FDG) to assess metabolic function in the infarcted region. The paper focuses on practical aspects such as slice planning, accurate gating, drug delivery, segmentation of images, and multimodal coregistration. The methods presented here achieve good repeatability and accuracy maintaining a high throughput.

We describe how to perform MRI and PET imaging of the mouse heart. The protocol is tailored to assess treatment efficacy in models of myocardial infarction and heart failure.

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ...

Myocardial Infarction and Functional Outcome Assessment in Pigs

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One important prerequisite is a good understanding of all safety and efficacy aspects obtained in a large animal model that validly reflect the human scenario of myocardial infarction (MI). Pigs are widely used in this regard since their cardiac size, hemodynamics, and coronary anatomy are close to that of humans. Here, we present an effective protocol for using the porcine MI model using a closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. This approach is based on 90 min of myocardial ischemia, inducing large left ventricle infarction of the anterior, septal and inferoseptal walls. Furthermore, we present protocols for various measures of outcome that provide a wide range of information on the heart, such as cardiac systolic and diastolic function, hemodynamics, coronary flow velocity, microvascular resistance, and infarct size. This protocol can be easily tailored to meet study specific requirements for the validation of novel cardioregenerative biologics at different stages (i.e. directly after the acute ischemic insult, in the subacute setting or even in the chronic MI once scar formation has been completed). This model therefore provides a useful translational tool to study MI, subsequent adverse remodeling, and the potential of novel cardioregenerative agents.

This protocol describes the porcine myocardial infarction (MI) model using a 90 min closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. Furthermore, the protocol for several outcome parameters, such as cardiac function, hemodynamics, microvascular resistance, and infarct size, are also presented.

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One ...

A Hydrogel Construct and Fibrin-based Glue Approach to Deliver Therapeutics in a Murine Myocardial Infarction Model.

The murine MI model is widely recognized in the field of cardiovascular disease, and has consistently been used as a first step to test the efficacy of treatments in vivo1. The traditional, established protocol has been further fine-tuned to minimize the damage to the animal. Notably, the pectoral muscle layers are teased away rather than simply cut, and the thoracotomy is approached intercostally as opposed to breaking the ribs in a sternotomy, preserving the integrity of the ribcage. With these changes, the overall stress on the animal is decreased. 
Stem cell therapies aimed to alleviate the damage caused by MIs have shown promise over the years for their pro-angiogenic and anti-apoptotic benefits. Current approaches of delivering cells to the heart surface typically involve the injection of the cells either near the damaged site, within a coronary artery, or into the peripheral blood stream2-4. While the cells have proven to home to the damaged myocardium, functionality is limited by their poor engraftment at the site of injury, resulting in diffusion into the blood stream5. This manuscript highlights a procedure that overcomes this obstacle with the use of a cell-encapsulated hydrogel patch. The patch is fabricated prior to the surgical procedure and is placed on the injured myocardium immediately following the occlusion of the left coronary artery. To adhere the patch in place, biocompatible external fibrin glue is placed directly on top of the patch, allowing for it to dry to both the patch and the heart surface. This approach provides a novel adhesion method for the application of a delicate cell-encapsulating therapeutic construct.

This protocol aims to alleviate the limitation of poor cell engraftment for stem cell treatment of myocardial infarctions through the use of a hydrogel system and a fibrin-based glue. With this approach, cell-to-tissue contact post-infarction can be maintained, increasing the therapeutic potential of beneficial agents at the site of injury.

The murine MI model is widely recognized in the field of cardiovascular disease, and has consistently been used as a first step to test the efficacy of ...

Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction

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

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

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

Myocardial Infarction in Neonatal Mice, A Model of Cardiac Regeneration

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and regeneration, and to define new targets for therapeutics. For decades, models of complete heart regeneration existed in amphibians and fish, but a mammalian counterpart was not available. The recent discovery of a postnatal window during which mice possess regenerative capabilities has led to the establishment of a mammalian model of cardiac regeneration. A surgical model of mammalian cardiac regeneration in the neonatal mouse is presented herein. Briefly, postnatal day 1 (P1) mice are anesthetized by isoflurane and placed on an ice pad to induce hypothermia. After the chest is opened, and the left anterior descending coronary artery (LAD) is visualized, a suture is placed around the LAD to inflict myocardial ischemia in the left ventricle. The surgical procedure takes 10-15 min. Visualizing the coronary artery is crucial for accurate suture placement and reproducibility. Myocardial infarction and cardiac dysfunction are confirmed by triphenyl-tetrazolium chloride (TTC) staining and echocardiography, respectively. Complete regeneration 21 days post myocardial infarction is verified by histology. This protocol can be used to as a tool to elucidate mechanisms of mammalian cardiac regeneration after myocardial infarction.

This protocol describes a highly reproducible model of cardiac regeneration by surgical induction of myocardial infarction in the left ventricle of postnatal day 1 mice. The method involves induction of hypothermic anesthesia and ligation of the left anterior descending coronary artery.

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and ...

Improvement of a Closed Chest Porcine Myocardial Infarction Model by Standardization of Tissue and Blood Sampling Procedures

Myocardial ischemia reperfusion (I/R) injury contributes to almost half of the necrotic area after myocardial infarction. To date there is no approved drug to prevent or reduce myocardial I/R injury. The study and understanding of the pathophysiological mechanisms of myocardial I/R injury is essential to develop successful treatments. Large animal experiments are an important step in translational methods. The porcine model of acute myocardial infarction has been established and described by ourselves and others. We aimed to further improve the value of the model by focusing in detail on the sampling techniques for use in future experiments. Furthermore, we emphasize small but important steps that can affect the quality of the final results. To mimic the clinical situation of myocardial I/R injury, a percutaneous coronary intervention (PCI) catheter was inserted into the left anterior descending coronary artery (LAD) of an anesthetized pig. &#176;&#176;&#176;This model mimics acute myocardial infarction and PCI treatment in humans with the possibility of accurately determining the area at risk as well as the necrotic- and viable ischemic tissue. Here the model was used to investigate the effect of a bicyclic peptide inhibitor of FXIIa. The model can also be modified to allow longer reperfusion times to study later effects of myocardial infarction.

Here we demonstrate a protocol to standardize sampling procedures of an established porcine model of acute myocardial infarction in order to increase its translational value in the understanding of the pathophysiology of myocardial ischemia/reperfusion injury and to test novel drug candidates.

Myocardial ischemia reperfusion (I/R) injury contributes to almost half of the necrotic area after myocardial infarction. To date there is no approved ...

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 ...

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.

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 ...

Intramyocardial Transplantation of MSC-Loading Injectable Hydrogels after Myocardial Infarction in a Murine Model

One of the major issues facing current cardiac stem cell therapies for preventing postinfarct heart failure is the low retention and survival rates of transplanted cells within the injured myocardium, limiting their therapeutic efficacy. Recently, the use of scaffolding biomaterials has gained attention for improving and maximizing stem cell therapy. The objective of this protocol is to introduce a simple and straightforward technique to transplant bone marrow-derived mesenchymal stem cells (MSCs) using injectable hydroxyphenyl propionic acid (GH) hydrogels; the hydrogels are favorable as a cell delivery platform for cardiac tissue engineering applications due to their ability to be cross-linked in situ and high biocompatibility. We present a simple method to fabricate MSC-loading GH hydrogels (MSC/hydrogels) and evaluate their survival and proliferation in three-dimensional (3D) in vitro culture. In addition, we demonstrate a technique for intramyocardial transplantation of MSC/hydrogels in mice, describing a surgical procedure to induce myocardial infarction (MI) via left anterior descending (LAD) coronary artery ligation and subsequent MSC/hydrogels transplantation.

Stem cell-based therapy has emerged as an efficient strategy to repair injured cardiac tissues after myocardial infarction. We provide an optimal in vivo application for stem cell transplantation using gelatin hydrogels that are able to be enzymatically cross-linked.

One of the major issues facing current cardiac stem cell therapies for preventing postinfarct heart failure is the low retention and survival rates of ...