Name: induction of myocardial infarction and myocardial ischemia-reperfusion injury in mice
Uploaded: 2022-01-19T13:30:00
Description: Watch this Scientific Journal Video about Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice at JoVE.com

This work was supported by the National Natural Science Foundation of China (82070317, 81700390 to Jibin Lin, 8210021880 to Bingjie Lv and 82000428 to Boyuan Wang) and the National Key R&#38;D Program of China ( 2017YFA0208000 to Shaolin He).

Animal studies have been approved by the Animal Care and Utilization Committee of Huazhong University of Science and Technology (Wuhan, China).
NOTE: Male C57BL/6J mice (8-10 weeks) are used as models. Mice have free access to food and water and are bred in specific pathogen-free conditions. The room is maintained under controlled temperature (22 &#176;C &#177; 2 &#176;C) and humidity (45%-65%). Mice are exposed to a 12-h light/dark environment at the Animal Care Facility of Tongji Medical Sch...

<ol>
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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+myocardial+infarction.">Acute myocardial infarction.</a> New England Journal of Medicine. 376 (21), 2053-2064 (2017).</li><li>Frank, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+ischemia+reperfusion+injury:+From+basic+science+to+clinical+bedside.">Myocardial ischemia reperfusion injury: From basic science to clinical bedside.</a> Seminars in Cardiothoracic and Vascular Anesthesia. 16 (3), 123-132 (2012).</li><li>Mares, R. 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In recent years, the creation of models for MI and MIRI in clinical and scientific research has developed rapidly20,21. However, there are still some questions, such as the mechanisms of actions and how to ameliorate MI/MIRI, that must be resolved. Here, a modified protocol for establishing a murine model of MI and MIRI is described. Several key points must be considered carefully.
The first key point is endotracheal intubation. Some p...

Acute myocardial infarction (AMI) is a common cardiovascular disease worldwide and carries high mortality1. Advances in technologies make early and efficacious revascularization available for AMI patients. After these treatments in some patients, myocardial ischemia-reperfusion injury (MIRI) can occur2. Thus, it is of great significance to understand the mechanisms of actions and how to ameliorate MI/MIRI. Mice are widely used as models because of their low cost, rapid breeding time, and ease for making genetic alterations3. Scholars have developed different methods to model MIRI and MI in animal4,5,6,7,8,9. This strategy promotes research, but the different criteria and methods employed complicate the interpretation of results among research teams.
In mice, MI has been induced by isoproterenol10, cryoinjury11,12, or cauterization13. MI can be induced readily by isoproterenol, but the pathophysiological process is different from that in clinical MI. Cryoinjury-induced MI has poor consistency, elicits excessive myocardial damage around the left anterior descending coronary artery (LAD), and can easily induce arrhythmia. Cauterization-induced MI is quite different from the natural process of myocardial infarction, and the inflammatory reaction in the burning area is more intense; in addition, the surgical approach has technical difficulties. Moreover, there are some labs14 developing MI model in minipigs using balloon blocking or embolization or thrombosis method through interventional technique. All these methods can cause coronary artery occlusion directly, but needing coronary angiography devices and, above all, the too-thin mouse coronary arteries makes these operations not practical. For MIRI, the differences among different models were quite modest, such as using respirators /micromanipulation or not5,6.
Here, a simple and reliable method that can induce MI and the MIRI model, adapted from previously published methods4,5,6,7,8,9,15, is described. This method can simulate pathophysiological processes by direct blockade of the LAD through ligation. Moreover, by relieving the ligation, this model can also simulate reperfusion injury. In this protocol, a dissecting microscope is used for LAD visualization. Then, the researcher can identify the LAD readily. Subsequently, accurate ligation of the LAD leads to reproducible and predictable blood occlusion and ventricular ischemia. Moreover, electrocardiography (ECG) changes can be used to confirm ischemia and reperfusion in addition to the color changes of the LAD observed under a microscope. This strategy leads to a shorter procedure duration, lower surgical complications risk, and fewer experimental mice needed. The methods for the troponin-T test, cardiac ultrasound, and triphenyl tetrazolium chloride (TTC) staining are also described. Overall, this protocol is useful for studies of MI/MIR mechanism, as well as for drug discovery.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.9 % sodium chloride solution</td>
			<td>Kelun Industry Group,China</td>
			<td></td>
			<td>-</td>
		</tr>
		<tr>
			<td>4% paraformaldehyde fixing solution</td>
			<td>Servicebio,China</td>
			<td>G1101</td>
			<td>-</td>
		</tr>
		<tr>
			<td>4-0 silk suture</td>
			<td>Shanghai Pudong Jinhuan Medical Products,China</td>
			<td>C412</td>
			<td>-</td>
		</tr>
		<tr>
			<td>8-0 suture</td>
			<td>Shanghai Pudong Jinhuan Medical Products,China</td>
			<td>H801</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>IsoReag,China</td>
			<td>IR-11190</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Camera</td>
			<td>Canon,Japan</td>
			<td>EOS 80D</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Depilatory cream</td>
			<td>Veet,French</td>
			<td></td>
			<td>-</td>
		</tr>
		<tr>
			<td>Elecsys Troponin T hs STAT</td>
			<td>Roche,Germany</td>
			<td></td>
			<td>-</td>
		</tr>
		<tr>
			<td>Electrochemical luminescence immunoanalyzer</td>
			<td>Roche,Germany</td>
			<td>Elecsys 2010</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Evans blue</td>
			<td>Sigma,America</td>
			<td>E2129</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Eye scissors</td>
			<td>Shanghai Medical Instruments,China</td>
			<td>JC2303</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Haemostatic forceps</td>
			<td>Shanghai Medical Instruments,China</td>
			<td>J31020</td>
			<td>-</td>
		</tr>
		<tr>
			<td>High frequency in vivo imaging systems</td>
			<td>Visualsonics,Canada</td>
			<td>Vevo2100</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Ibuprofen</td>
			<td>PerFeMiKer,China</td>
			<td>CLS-12921</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Intravenous catheter</td>
			<td>Introcan,Germany</td>
			<td>4254090B</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Sigma-Aldrich,America</td>
			<td>&#160;K2753</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Medical alcohol</td>
			<td>Huichang ,China</td>
			<td></td>
			<td>-</td>
		</tr>
		<tr>
			<td>Microneedle holders</td>
			<td>Shanghai Medical Instruments,China</td>
			<td>WA2040</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Microscopic shears</td>
			<td>Shanghai Medical Instruments,China</td>
			<td>WA1040</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Microsurgical forceps</td>
			<td>Shanghai Medical Instruments,China</td>
			<td>WA3020</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Mouse electrocardiograph</td>
			<td>Techman,China</td>
			<td>BL-420F</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Needle holders</td>
			<td>Shanghai Medical Instruments,China</td>
			<td>JC3202</td>
			<td>-</td>
		</tr>
		<tr>
			<td>operating floor</td>
			<td>Chico,China</td>
			<td>ZK-HJPT</td>
			<td>-</td>
		</tr>
		<tr>
			<td>PE-10 tube</td>
			<td>Huamei,China</td>
			<td></td>
			<td>-</td>
		</tr>
		<tr>
			<td>Pentobarbital</td>
			<td>Merck,America</td>
			<td>1030001</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Rodent Ventilator</td>
			<td>Shanghai Alcott Biotech,China</td>
			<td>ALC-V8S-P</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Stereo microscope</td>
			<td>Aomei Industry,China</td>
			<td>SZM0745-STL3-T3</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Surgical thermostatic heating pad</td>
			<td>Globalebio, China</td>
			<td>GE0-20W</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Triphenyltetrazolium chloride</td>
			<td>Servicebio,China</td>
			<td>G1017</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Huamaike Biochemicals and Life Science Research Prouducts,China</td>
			<td>323004</td>
			<td>-</td>
		</tr>
	</tbody>
</table>

induction of myocardial infarction and myocardial ischemia-reperfusion injury in mice

Acute myocardial infarction is a common cardiovascular disease with high mortality. Myocardial reperfusion injury can counteract the beneficial effects of heart reflow and induce secondary myocardial injury. A simple and reproducible model of myocardial infarction and myocardial ischemia-reperfusion injury is a good tool for researchers. Here, a customizable method to create a myocardial infarction (MI) model and MIRI by precision ligation of the left anterior descending coronary artery (LAD) through micromanipulation is described. Accurate and reproducible ligature positioning of the LAD helps obtain consistent results for heart injury. ST-segment changes can help to identify model accuracy. The serum level of cardiac troponin T (cTnT) is used to assess the myocardial injury, cardiac ultrasound is employed to evaluate the myocardial systolic function, and Evans-Blue/triphenyl tetrazolium chloride staining is used to measure infarct size. In general, this protocol reduces procedure duration, ensures controllable infarct size, and improves mouse survival.

The experimental workflow is shown in Figure 1A. The researcher can schedule the time nodes according to the experimental design upon study initiation. The duration of LAD ligation is according to the research purpose. For MI, the research can ignore the reperfusion step. Cardiac ultrasound is available at different stages of the study because it is non-invasive, while Evans-Blue/TTC staining can be performed only when the mouse is sacrificed. For research that focuses on fibrosis and ventri...

Watch this Scientific Journal Video about Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice at JoVE.com

Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice

Here we describe a simple and reproducible method that can induce myocardial infarction or myocardial ischemia-reperfusion injury in mice by precision ligation of the left anterior descending coronary artery through micromanipulation.

Acute myocardial infarction is a common cardiovascular disease with high mortality. Myocardial reperfusion injury can counteract the beneficial effects of ...

This study describes a customizable method to create a myocardial function model in Miro by precision ligation of the left anterior descending coronary artery through micro manipulation. This protocol reduces procedure duration, ensures controllable infarct size, and improves mouse survival. Use a rectangular OT with a heating pad pre-warmed to 37 degrees Celsius throughout the surgical procedure.Before the procedure, disinfect the board with ultraviolet light and 70%alcohol. Begin by placing the mouse on the OT in a supine position with gauze under the head to avoid overheating the eyes. Apply ophthalmic ointment to the eyes to prevent them from drying out.Use a fur removal cream on the thorax and massage evenly with a sterile cotton swab for one minute. Wipe the excess fur with gauze. Use povidone iodine followed by 70%alcohol to clean the area, and cover the thorax with gauze.Use a 4-O suture under the upper incisors and secure it to the anchor point to keep the mouth slightly open and facilitate cannulation. Pull the tail to keep the body straight, and secure it to the OT using tape. Secure the four limbs with tape and tighten them on the anchor points.Do not overstretch the front limbs to avoid respiratory compromise. Use forceps to open the jaw and lift the tongue. Then use an illuminator to visualize the throat and glottis.Gently insert a 22 gauge cannula with a blunt truncated needle through the mouth into the trachea, about one centimeter down the throat. Use one hand to hold the tongue and move it slightly upwards with blunt forceps. Simultaneously use the other hand to gently insert the tube into the trachea.Be careful not to insert the tube into the esophagus. Carefully remove the needle. Before connecting to the ventilator check the intubation by placing the tube into the water for bubbles to form.Connect the endotracheal tube to a ventilator set to 120 per minute, and tidal volume adjusted to 250 microliters. Verify intubation by checking bilateral symmetrical chest expansion. Then fix the connection to the OT with tape to avoid it falling off.Place ECG electrodes on the paws and connect them to the ECG recorder. Monitor cardiac electrophysiology throughout the procedure. Remove the gauze on the thorax.Disinfect the incision area using three scrub cycles with 70%alcohol. To reduce contamination of the surgical site, cover the mouse with a sterile surgical drape with a hole over the surgical field. After making an oblique skin incision with a scalpel, expose the ribs by carrying out a blunt dissection of the subcutaneous tissues.Be careful not to injure the vessels, ribs, and lungs. Use sterile cotton applicators to stop the bleeding. Identify the third intercostal space and make an incision of about six to eight millimeters.Then open the chest cavity by carrying out blunt dissection of tissues in the intercostal space. Be careful not to injure the internal thoracic artery. Span the intercostal space using forceps.Insert pre sterilized homemade retractors into the ribcage, and pull back to spread the incision to approximately six millimeters in width. Attach the retractors to the OT with rubber bands. Carefully remove the surrounding tissues to expose the heart entirely.Pull off the pericardium gently with curved forceps without injuring the heart. Use a dissecting microscope and direct a focused and appropriate light for LAD visualization. Gently press the site below the chosen ligation position to temporarily enlarge the LAD, and then recheck the LAD.Under a dissecting microscope, use a tapered needle to pass an 8-0 silk ligature underneath the LAD. Ensure that the needle is not deep enough to enter the left ventricle and not too shallow to avoid damaging the LAD. Tie the ligature with a loose double knot.Place a two to three millimeter PE-10 tubing into a loop parallel to the artery. Tighten the ligature loop gently until it is around the artery and tubing. Then secure the loop with a slip knot.Take care not to damage the myocardial wall with excessive tightening pressure. A pallor coloration in the anterior wall of the left ventricle after ligation confirms cessation of blood flow in the LAD. If permanent ligation is required, proceed as described in the text manuscript.Remove the retractors from the incision. Then close the wound temporarily with a bulldog clamp. Ensure that the mouse continues to be connected to the ventilator.When the period of ischemia ends, remove the bulldog clamp and insert the retractors to open the incision and expose the heart and the ligation site. Untie the slip knot and remove the PE-10 tubing. Change in the pale coloration to pink-red confirms blood flow restoration.Simultaneously, to detect reperfusion, observe the ECG for a potential dissolution of ST elevation. Leave the 8-0 ligature in situ if performing subsequent Evans blue and TTC staining. Otherwise, remove the suture at this step.Remove the retractors and close the incision by suturing the third and fourth ribs with a 4-O silk suture. Be careful not to injure the lung. Press the chest gently while tying the suture knots to push out any air that might be trapped in the chest cavity.Close the muscle layers with continuous 4-O silk sutures. The standard images of the experimental process were acquired from endotracheal intubation, skin incision, thoracotomy, LAD identification, and ligation, to reperfusion. The representative ECG images verified myocardial ischemia and reperfusion with significant ST elevation after ligation.And dissolution of ST elevation after the slip knot was untied. Before the thoracotomy, it is very important to keep the airway open, and the most important thing is to make sure that the LAD is firmly ligated and avoid damage. This procedure will be followed by echocardiography to evaluate the cardiac function as well as TTC to assess the myocardial injury.

Research

JoVE Journal

Medicine

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 ...

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Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

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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 ...