This work was supported by grants from the National Natural Science Foundation of China (81930007, 81625002, 81800307, 81470389, 81500221, 81770238), the Shanghai Outstanding Academic Leaders Program (18XD1402400), the Science and Technology Commission of Shanghai Municipality (201409005200), Shanghai Pujiang Talent Program (2020PJD030), and China Postdoctoral Science Foundation (2020M671161, BX20190216).

The experiments involving animal work are performed with all necessary approvals from the Laboratory Animal Welfare Ethics Committee of Renji Hospital, Shanghai Jiao Tong University, School of Medicine (R52021-0506). Female and male C57BL/6J mice aged between 8-10 weeks were used in the study.
1. Preparation of the simplified anesthesia equipment (OPTIONAL)
NOTE: This is an optional pre-operative set up and can be replaced with titratable anesthesia as mentioned in section 2. The institutional animal ethics committee and veterinarian(s) should be consulted prior to adapting this set up in animal procedures.
<ol>
	<li>Take a 15 mL centrifuge tube, and make a cut perpendicular to the long axis of the tube about 3 cm from the opening. 
	NOTE: Ensure that the cut is greater than half of the circular circumference of the tube lumen so that the valve can be successfully inserted.</li>
	<li>Drill holes (diameter, 2 mm) at the centrifuge tube wall between the cut and the tube opening.</li>
	<li>Cut a suitably sized piece of the valve from a plastic sheet and insert the valve into the cut on the tube wall. 
	NOTE: The valve can be used to control the release rate of isoflurane by changing the depth of the insertion.</li>
	<li>Inside a fume hood, cut open the bottom of the tube and connect it to the oxygen supply. Place a cotton ball near the bottom end of the tube, add load 0.5 mL isoflurane (as obtained, see Table of Materials) onto the cotton ball, and close the valve.</li>
	<li>Test the anesthesia efficacy by masking the mice with tubes prepared as described above. Monitor the breathing rate and anesthesia depth by toe pinch response. 
	&#8203;NOTE: A breathing rate less than 10 times/10 s suggests excessive anesthesia, and the insertion depth of the valve should be adjusted.&#160;For all the procedures involving anesthesia, a gas filter filled with activated charcoal sheets must be used (Figure 1A-i), and surgery should be performed within a hood.</li>
</ol>
2. Operative preparation and anesthesia
<ol>
	<li>Prepare and sterilize all the required instruments on the day of surgery, including a pair of forceps, a micro-mosquito hemostat, a pair of surgical scissors, two pairs of needle holders, 4-0 silk surgical suture, 6-0 silk surgical suture, a gas filter, and a light source (see Table of Materials) (Figure 1A).</li>
	<li>Put on a surgical mask and sterile gloves.</li>
	<li>Apply the depilatory cream to the mouse chest and wait for 1 min. Gently wipe off the depilatory cream and hair with wet gauze.</li>
	<li>Hold the mouse with the dominant hand after depilation.&#160;Induce anesthesia via inhalation of vaporized isoflurane (4%) with oxygen supply (1L/min) and maintain at 2-3% isoflurane.</li>
	<li>Confirm adequate anesthesia by the lack of toe pinch response.</li>
	<li>Apply sterile eye cream to both eyes to prevent corneal dryness.</li>
	<li>Secure the mice on a surgery platform in the supine position. Apply povidone-iodine swabs (see Table of Materials) to the chest three times and cover the disinfected chest with a sterile drape.</li>
</ol>
3. Induction of myocardial infarction
<ol>
	<li>Change the contaminated gloves to ensure sterility.</li>
	<li>Make a 0.5 cm skin cut along the line connecting the xiphoid and armpit after local block with lidocaine.</li>
	<li>Bluntly separate the pectoral major and pectoral minor muscles using forceps and a micro-mosquito hemostat to expose the fourth intercostal space.</li>
	<li>Open the fourth intercostal space using a micro-mosquito hemostat.</li>
	<li>Externalize the heart by pushing the heart toward the fourth intercostal space with the index finger of the left hand.</li>
	<li>Secure the heart with the left hand, and ligate the left anterior descending branch with a 6-0 suture 3 mm from its origin.</li>
	<li>Place the heart back into the thoracic cavity quickly. 
	NOTE: It is safe to externalize the heart for less than 30 s.</li>
	<li>Evacuate the air out of the thoracic cavity by a gentle press of the chest cavity manually.</li>
	<li>Close the muscle layer over the ribs with a 6-0 silk suture.</li>
	<li>Close the skin with a 4-0 silk suture.</li>
	<li>Place the mice on a pad (37 &#176;C) immediately after the operation.</li>
	<li>Inject buprenorphine (0.05-0.1mg/kg) subcutaneously every 4-6 hours to reduce post-operative pain for up to 72 hours.</li>
	<li>Return the operated mice to cages when fully recovered. 
	NOTE: The mice will be fully recovered within 3-5 min after surgery.</li>
	<li>Carefully monitor the mice and provide wet food for up to 7 days.</li>
</ol>
4. Harvesting the tissues
<ol>
	<li>Sacrifice the mice at different time points after MI establishment by cervical dislocation.</li>
	<li>Secure the sacrificed mice on the surgery platform in the supine position.</li>
	<li>Make a ventral incision (~3-4 cm) in the upper abdomen. Cut off the ribs from both sides of the thorax cavity, and remove the diaphragm.</li>
	<li>Perfuse the heart with 10 mL cold phosphate-buffered saline (1x PBS, 4 &#176;C) through intraventricular injection.</li>
	<li>Collect the heart by cutting off the aortic root and immediately store the heart at -80 &#176;C. 
	NOTE: According to the authors&#39; experience, it is feasible to perform TTC staining within two weeks of storage.</li>
	<li>Stain the heart with 2,3,5-Triphenyltetrazolium chloride (TTC).
	<ol>
		<li>Slice the frozen heart into 1 mm thick sections on ice using razor blades.</li>
		<li>Incubate the prepared heart slices in 1% TTC solution (dissolved in 1x PBS) at 37 &#176;C for 10-15 min. 
		NOTE: After 15 min incubation, discard the TTC solution and immerse the stained heart slices into 1x PBS.</li>
	</ol>
	</li>
	<li>Photograph the slices using a digital camera.</li>
</ol>

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A method of coronary occlusion in small animals.</a> Annals of Surgery. 140 (5), 675-682 (1954).</li><li>Ahn, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+myocardial+infarcts+of+a+predictable+size+and+location+by+branch+pattern+probability-assisted+coronary+ligation+in+C57BL/6+mice.">Induction of myocardial infarcts of a predictable size and location by branch pattern probability-assisted coronary ligation in C57BL/6 mice.</a> American Journal of Physiology. Heart and Circulatory Physiology. 286 (3), 1201-1207 (2004).</li><li>Gao, E., Koch, W. 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The authors have nothing to disclose.

The present report demonstrated a easy&#160;protocol for MI induction in mice with readily available materials, which was modified from a method reported by Gao16. Murine MI models are indispensable for mechanistic exploration and drug screen for post-MI dysfunction and remodeling12. Among the existing techniques for MI induction, coronary artery ligation represents the most commonly practiced one. Coronary artery ligation faithfully recapitulates the ischemia nature of myo...

Myocardial infarction (MI) represents one of the significant causes of death and disability worldwide1,2,3,4,5. Despite timely reperfusion, there is currently a lack of effective therapies to treat post-MI cardiac remodeling. Correspondingly, considerable efforts have been made to mechanistic exploration and therapy exploitation for MI6,7,8. Of note, the establishment of MI models is a prerequisite to meet these ends.
Several methods (e.g., isoproterenol treatment, cryoinjury, coronary artery ligation, etc.) have been proposed to induce MI models in small animals. Isoproterenol treatment is a simple method for MI induction, but it cannot induce infarction of the targeted area9. Cryoinjury leads to myocardial necrosis via the generation of ice crystals and disruption of the cell membrane rather than direct ischemia10. By contrast, coronary artery ligation permits precise control of occlusion site and extent of infarct area and faithfully recapitulates remodeling response following infarction11,12. Coronary artery ligation is typically performed following intubation, mechanical ventilation, and thoracotomy, which is technically challenging13,14. Several modified protocols for coronary artery ligation (e.g., ventilation free) were reported and potentiated the induction of MI, but detailed visual demonstrations are lacking15,16,17. These issues pose a significant financial and technical barrier for groups wishing to engage in research using MI models. This report presents an approach for induction of MI in mice. The current method is easy, timesaving, and uses surgical tools and equipment found readily in most laboratories.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2,3,5-Triphenyltetrazolium chloride</td>
			<td>SIGMA</td>
			<td>T8877-25G</td>
			<td>TTC staining</td>
		</tr>
		<tr>
			<td>4-0 silk suture</td>
			<td>YUANKANG</td>
			<td>4-0</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Autoclave</td>
			<td>HIRAYAMA</td>
			<td>HVE-50</td>
			<td>Sterilization for the solid</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Qinghai Pharmaceutical FACTORY Co., Ltd.</td>
			<td>H10940181</td>
			<td>reduce post-operative pain</td>
		</tr>
		<tr>
			<td>Centrifugation tube</td>
			<td>Biological Hope</td>
			<td>1850-K</td>
			<td>15ML</td>
		</tr>
		<tr>
			<td>Depilatory cream</td>
			<td>ZIKER BIOTECHNOLOGY</td>
			<td>ZK-L2701</td>
			<td>Depilation agent for laboratory animals</td>
		</tr>
		<tr>
			<td>Forcep</td>
			<td>RWD</td>
			<td>F12028</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Gas filter</td>
			<td>ZHAOXIN</td>
			<td>SA-493</td>
			<td>Operator protection</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>RWD</td>
			<td>20071302</td>
			<td>Used for anesthesia</td>
		</tr>
		<tr>
			<td>Light source</td>
			<td>Beijing PDV</td>
			<td>LG-150B</td>
			<td>Operating lamp</td>
		</tr>
		<tr>
			<td>Micro-mosquito hemostat</td>
			<td>FST</td>
			<td>13011-12</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Needle</td>
			<td>BINXIONG</td>
			<td>42180104</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Needle and the 6-0 silk suture</td>
			<td>JIAHE</td>
			<td>SC086</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Needle holder</td>
			<td>ShangHaiJZ</td>
			<td>J32030</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Needle holder</td>
			<td>ShangHaiJZ</td>
			<td>J32010</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Povidone-iodine swabs</td>
			<td>SingleLady</td>
			<td>GB26368-2010</td>
			<td>Skin disinfection</td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>CNSTRONG</td>
			<td>JYJ1030</td>
			<td>Surgical instrument</td>
		</tr>
		<tr>
			<td>Sterile eye cream</td>
			<td>Shenyang Xingqi Pharmaceutical Co., Ltd.</td>
			<td>H10940177</td>
			<td>prevent corneal dryness</td>
		</tr>
		<tr>
			<td>Ultra-high resolution ultrasound imaging system for small animals</td>
			<td>VisualSonics</td>
			<td>Vevo 2100</td>
			<td>Echocardiographic analysis</td>
		</tr>
	</tbody>
</table>

a modified simple method for induction of myocardial infarction in mice

Myocardial infarction (MI) represents one of the leading causes of death. MI models are widely used for investigating the pathomechanisms of post-MI remodeling and evaluation of novel therapeutics. Different methods (e.g., isoproterenol treatment, cryoinjury, coronary artery ligation, etc.) have been used to induce MI. Compared with isoproterenol treatment and cryoinjury, coronary artery ligation may better reflect the ischemic response and chronic remodeling after MI. However, traditional methods for coronary ligation in mice are technically challenging. The current study describes a simple and efficient process for induction of MI in mice with readily available materials. The mouse chest skin was cut open under stable anesthesia. The heart was immediately externalized through the intercostal space after blunt separation of the pectoralis major and pectoralis minor. The left anterior descending branch (LAD) was ligated with a 6-0 suture 3 mm from its origin. Following LAD ligation, staining with 2,3,5-Triphenyltetrazolium chloride (TTC) indicated successful induction of MI and temporal changes of post-MI scar size. Meanwhile, survival analysis results showed overt mortality within 7 days after MI, mainly due to cardiac rupture. Moreover, post-MI echocardiographic assessment demonstrated successful induction of contractile dysfunction and ventricular remodeling. Once mastered, an MI model can be established in mice within 2-3 min with readily available materials.

The experimental protocol and some of the critical steps are shown in Figure 1. The simplified anesthesia equipment induced anesthesia. As shown in Figure 2A, the induced anesthesia was stable, as reflected by the regular breathing rates (varied from 90-107 breaths/min in the tested mice). Following coronary artery ligation, TTC staining analysis indicated successful induction of myocardial infarction and temporal changes of post-MI scar size (<strong class="xfi...

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A Modified Simple Method for Induction of Myocardial Infarction in Mice

Under adequate anesthesia, the mouse heart was externalized through the intercostal space, and myocardial infarction was successfully induced by ligating the left anterior descending artery (LAD) using materials readily available in most laboratories.

Myocardial infarction (MI) represents one of the leading causes of death. MI models are widely used for investigating the pathomechanisms of post-MI ...

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3.4K Views.  The First Affiliated Hospital of Bengbu Medical College. Under adequate anesthesia, the mouse heart was externalized through the intercostal space, and myocardial infarction was successfully induced by ligating the left anterior descending artery (LAD) using materials readily available in most laboratories.

Video: A Modified Simple Method for Induction of Myocardial Infarction in Mice

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 ...

A Simple Guide Screw Method for Intracranial Xenograft Studies in Mice

The grafting of human tumor cells into the brain of immunosuppressed mice is an established method for the study of brain cancers including glioblastoma (glioma) and medulloblastoma. The widely used stereotactic approach only allows for the injection of a single animal at a time, is labor intensive and requires highly specialized equipment. The guide screw method, initially developed by Lal et al.,1 was developed to eliminate cumbersome stereotactic procedures. We now describe a modified guide screw approach that is rapid and exceptionally safe; both of which are critical ethical considerations. Notably, our procedure now incorporates an infusion pump that allows up to 10 animals to be simultaneously injected with tumor cells.
To demonstrate the utility of this procedure, we established human U87MG glioma cells as intracranial xenografts in mice, which were then treated with AMG102; a fully human antibody directed to HGF/scatter factor currently undergoing clinical evaluation2-5. Systemic injection of AMG102 significantly prolonged the survival of all mice with intracranial U87MG xenografts and resulted in a number of complete cures. 
This study demonstrates that the guide screw method is an inexpensive, highly reproducible approach for establishing intracranial xenografts. Furthermore, it provides a relevant physiological model for validating novel therapeutic strategies for the treatment of brain cancers.

In order to evaluate novel therapeutic paradigms for the treatment of glioma, physiological relevant models are essential. We utilize an implantable guide screw procedure for establishment of intracranial xenograft models that is more rapid and safer than stereotactic approaches.

The grafting of human tumor cells into the brain of immunosuppressed mice is an established method for the study of brain cancers including glioblastoma ...

Induction of Myocardial Infarction in Adult Zebrafish Using Cryoinjury

The mammalian heart is incapable of significant regeneration following an acute injury such as myocardial infarction1. By contrast, urodele amphibians and teleost fish retain a remarkable capacity for cardiac regeneration with little or no scarring throughout life2,3. It is not known why only some non-mammalian vertebrates can recreate a complete organ from remnant tissues4,5. To understand the molecular and cellular differences between regenerative responses in different species, we need to use similar approaches for inducing acute injuries.
In mammals, the most frequently used model to study cardiac repair has been acute ischemia after a ligation of the coronary artery or tissue destruction after cryoinjury6,7. The cardiac regeneration in newts and zebrafish has been predominantly studied after a partial resection of the ventricular apex2,3. Recently, several groups have established the cryoinjury technique in adult zebrafish8-10. This method has a great potential because it allows a comparative discussion of the results obtained from the mammalian and non-mammalian species.
Here, we present a method to induce a reproducible disc-shaped infarct of the zebrafish ventricle by cryoinjury. This injury model is based on rapid freezing-thawing tissue, which results in massive cell death of about 20% of cardiomyocytes of the ventricular wall. First, a small incision was made through the chest with iridectomy scissors to access the heart. The ventricular wall was directly frozen by applying for 23-25 seconds a stainless steel cryoprobe precooled in liquid nitrogen. To stop the freezing of the heart, fish water at room temperature was dropped on the tip of the cryoprobe. The procedure is well tolerated by animals, with a survival rate of 95%.
To characterize the regenerative process, the hearts were collected and fixed at different days after cryoinjury. Subsequently, the specimen were embedded for cryosectioning. The slides with sections were processed for histological analysis, in situ hybridization and immunofluorescence. This undertaking enhances our understanding of the factors that are required for the regenerative plasticity in the zebrafish, and provide new insights into the machinery of cardiac regeneration. A conceptual and molecular understanding of heart regeneration in zebrafish will impact both developmental biology and regenerative medicine.

Zebrafish represents a valuable model to study the mechanisms of heart regeneration in vertebrates. Here, we present a protocol for induction of a heart infarct in adult zebrafish using cryoinjury. This method results in massive cell death within 20% of the ventricular wall, similar to that observed in mammalian infarcts.

The mammalian heart is incapable of significant regeneration following an acute injury such as myocardial infarction1. By contrast, urodele amphibians and ...

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 ...

Minimal Invasive Surgical Procedure of Inducing Myocardial Infarction in Mice

Myocardial infarction still remains the main cause of death in western countries, despite considerable progress in the stent development area in the last decades. For clarification of the underlying mechanisms and the development of new therapeutic strategies, the availability of valid animal models are mandatory. Since we need new insights into pathomechanisms of cardiovascular diseases under in vivo conditions to combat myocardial infarction, the validity of the animal model is a crucial aspect. However, protection of animals are highly relevant in this context. Therefore, we establish a minimally invasive and simple model of myocardial infarction in mice, which assures a high reproducibility and survival rate of animals. Thus, this models fulfils the requirements of the 3R principle (Replacement, Refinement and Reduction) for animal experiments and assure the scientific information needed for further developing of therapeutical strategies for cardiovascular diseases.

A highly reproducible model for myocardial infarction in mice with minimal invasive manipulations is described. The model can be easily performed, resulting in a high reproducibility and survival rate. Thus, the described model will reduce the number of required animals as requested by the 3R principle (Replacement, Refinement and Reduction).

Myocardial infarction still remains the main cause of death in western countries, despite considerable progress in the stent development area in the last ...

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 ...

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 ...

Real-time Pressure-volume Analysis of Acute Myocardial Infarction in Mice

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any potential therapeutic approach directed against acute left ventricular (LV) dysfunction. Current imaging modalities (e.g., echocardiography and magnetic resonance imaging) have several limitations since data on LV pressure cannot directly be measured. LV catheterization in mice undergoing coronary artery occlusion could serve as a novel method for a real-time evaluation of LV function.
At the beginning of the procedure, mice were anesthetized followed by endotracheal intubation. For LV catheterization, the right carotid artery was exposed via middle-neck incision. The catheter was introduced and placed into the LV cavity. Left thoracotomy was conducted and the left main coronary artery (LCA) was ligated. To induce reperfusion, the suture was released after 45 min. Pressure-volume data was recorded at all times.
Ligation of the LCA caused a decrease in LV systolic function as evidenced by a 30% reduction in stroke volume, LV ejection fraction (EF), and cardiac output. Maximum dP/dt as a parameter for LV contractility was also significantly reduced and diastolic function was severely impaired (minimum dP/dt -40%). Reperfusion over a period of 20 min did not lead to a complete recovery of LV function.
Real-time pressure-volume analysis served as a valid procedure for monitoring cardiac function during acute myocardial infarction in mice. Maintaining stable anesthesia and a standardized surgical approach was crucial to ensure valid results. As the early phase of acute myocardial infarction is critical for morbidity and mortality, the delineated method could be beneficial for preclinical evaluation of new strategies for cardioprotection.

Acute myocardial infarction in mice induces acute but incompletely characterized changes in left ventricular (LV) function. LV catheterization in mice undergoing coronary artery occlusion serves as a novel method for a real-time evaluation of LV function.

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any ...