Name: left coronary artery ligation: a surgical murine model of myocardial infarction
Uploaded: 2022-08-09T14:45:00
Description: Watch this Scientific Journal Video about Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction at JoVE.com

This work was supported by National Institute of Health grants (R01HL143967, R01HL142629, R01AG069399, and R01DK129339), AHA Transformational Project Award (19TPA34910142), AHA Innovative Project Award (19IPLOI34760566), and ALA Innovation Project Award (IA-629694) (to PD).

The present study protocol was reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Pittsburgh. Eight (sham n = 4 and MI n = 4) 1-year-old female C57BL/6J mice weighing 24-30 g were used for these experiments. Approximately 100% and at least 80% of mice survived in the first 24 h and 28 days, respectively.
1. Preparation and endotracheal intubation of the mice
<ol>
	<li>Preheat a bead sterilizer (see Table of Materials...

<ol>
	<li>Virani, S. S., 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=Heart+disease+and+stroke+statistics-2021+update:+a+report+from+the+American+Heart+Association.">Heart disease and stroke statistics-2021 update: a report from the American Heart Association.</a> Circulation. 143 (8), 254 (2021).</li><li>Mendis, S., 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=World+Health+Organization+definition+of+myocardial+infarction:+2008-09+revision.">World Health Organization definition of myocardial infarction: 2008-09 revision.</a> International Journal of Epidemiology. 40 (1), 139-146 (2011).</li><li>Frangogiannis, N. 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P., 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=Preclinical+models+of+myocardial+infarction:+from+mechanism+to+translation.">Preclinical models of myocardial infarction: from mechanism to translation.</a> British Journal of Pharmacology. 179 (5), 770-791 (2022).</li><li>De Villiers, C., Riley, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+myocardial+infarction:+comparing+permanent+ligation+and+ischaemia-reperfusion.">Mouse models of myocardial infarction: comparing permanent ligation and ischaemia-reperfusion.</a> Disease Models &amp; Mechanisms. 13 (11), (2020).</li><li>Vasamsetti, S. 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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=General+anesthesia+in+cardiac+surgery:+a+review+of+drugs+and+practices.">General anesthesia in cardiac surgery: a review of drugs and practices.</a> The Journal of Extra-Corporeal Technology. 37 (2), 227-235 (2005).</li><li>Kolk, M. V., 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=LAD-ligation:+a+murine+model+of+myocardial+infarction.">LAD-ligation: a murine model of myocardial infarction.</a> Journal of Visualized Experiments. (32), e1438 (2009).</li><li>Wu, Y., Yin, X., Wijaya, C., Huang, M. -. H., McConnell, B. K. <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+in+rats.">Acute myocardial infarction in rats.</a> Journal of Visualized Experiments. (48), e2464 (2011).</li><li>Kalogeris, T., Baines, C., Krenz, M., Korthuis, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+six-cell+biology+of+ischemia/reperfusion+injury.">Chapter six-cell biology of ischemia/reperfusion injury.</a> International Review of Cell and Molecular Biology. , 229-317 (2012).</li><li>Scofield, S. 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(178), e63042 (2021).</li></ol>

The murine model of MI is gaining popularity in cardiovascular research laboratories, and this study describes a reproducible and clinically relevant MI model. This protocol improves the LCA ligation process in several ways. To begin with, the use of injectable pre-operative anesthetics such as xylazine/ketamine or sodium pentobarbital14,15 is avoided. Only isoflurane anesthesia was used, which helps enhance animal survival rates (&#62;80% survival 28 days after ...

Cardiovascular disease is a major public health concern that claims 17.9 million lives each year, accounting for 31 percent of global mortality1. The most prevalent type of cardiovascular anomaly is coronary heart disease, and myocardial infarction (MI) is one of the major manifestations of coronary heart disease2. MI is usually caused by thrombotic occlusion of a coronary artery due to the rupture of a vulnerable plaque3. The resulting ischemia causes profound ionic and metabolic changes in the affected myocardium, as well as a rapid decrease in systolic function. MI results in the death of cardiomyocytes, which can further lead to ventricular dysfunction and heart failure4.
Research on MI in patients is limited due to the scarcity of tissues obtained from patients with MI5. As such, murine models of MI are useful in both studying disease mechanisms as well as developing potential therapeutic targets. Currently available murine models of MI includeirreversible ischemia models (LCA and ablation methods) and reperfusion models (ischemia/reperfusion, I/R)6. Permanent ligation of the left coronary artery (LCA) in mice is the most used method, and it imitates the pathophysiology and immunology of MI in patients7,8,9. Permanent MI can also be induced by ablation methods, which involve electrical damage or cryoinjury. Ablation methods are able to generate uniform-sized infarction at the precise location10. On the other hand, scar formation, infarct morphology, and molecular signaling mechanisms may vary among the ablation methods10,11. The murine I/R method is another important MI model as it represents the clinical scenario of reperfusion therapy12. The I/R model is associated with challenges such as a variable infarct size, difficulty in distinguishing responses of initial injury, and reperfusion6.
Although widely used, LCA ligation methods are associated with low survival rates and post-operative pain13. This protocol demonstrates the murine surgical MI model of LCA ligation that involves the preparation and intubation of mice, LCA ligation, post-operative care, and validation of MI. Rather than using an invasive tracheotomy14, this method employs endotracheal intubation. The animal is intubated by illuminating the oropharynx using a laryngoscope, making the procedure easier, safer, and less traumatic15. The mouse is kept on ventilator support and under isoflurane anesthesia throughout the procedure. Further, echocardiography and Masson&#39;s trichrome staining are performed to evaluate heart function and cardiac fibrosis after MI, respectively. Overall, this method provides a reliable and reproducible surgical murine model of MI that can be used to study pathophysiology and inflammation after MI.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>22 G catheter needle</td>
			<td>Exel INT</td>
			<td>26741</td>
			<td>Thoracentesis</td>
		</tr>
		<tr>
			<td>24 G catheter needle</td>
			<td>Exel INT</td>
			<td>26746</td>
			<td>Endotracheal intubation</td>
		</tr>
		<tr>
			<td>4-0 nylon suture</td>
			<td>Covetrus</td>
			<td>29263</td>
			<td>Suturing of muscles and skin</td>
		</tr>
		<tr>
			<td>8-0 nylon suture</td>
			<td>S&#38;T</td>
			<td>3192</td>
			<td>Ligation of LAD</td>
		</tr>
		<tr>
			<td>Anesthetic Vaporizers</td>
			<td>Vet equip</td>
			<td>VE-6047</td>
			<td>Anesthetic support</td>
		</tr>
		<tr>
			<td>Animal physiology monitor</td>
			<td>Fujifilm</td>
			<td>VEVO 3100</td>
			<td>Monitor heart rate,respiration rate and body temperature</td>
		</tr>
		<tr>
			<td>Betadine solution</td>
			<td>PBS animal health</td>
			<td>11205</td>
			<td>Antispetic</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Covetrus</td>
			<td>55175</td>
			<td>Analgesic</td>
		</tr>
		<tr>
			<td>Disecting microscope</td>
			<td>OMANO</td>
			<td>OM2300S-V7</td>
			<td>Binocular</td>
		</tr>
		<tr>
			<td>Electric razor</td>
			<td>Wahl</td>
			<td>79300-1001M</td>
			<td>Shaving</td>
		</tr>
		<tr>
			<td>Electrode gel</td>
			<td>Parker Laboratories</td>
			<td>W60698L</td>
			<td>Electrically conductive gel</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Decon Laboratories</td>
			<td>22-032-601</td>
			<td>Disinfectant</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>FST</td>
			<td>11065-07</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Gauze</td>
			<td>Curity</td>
			<td>CAR-6339-PK</td>
			<td>Sterile</td>
		</tr>
		<tr>
			<td>Heat lamp</td>
			<td>Satco</td>
			<td>S4998</td>
			<td>Post surgery care</td>
		</tr>
		<tr>
			<td>Heating pad</td>
			<td>Kent scientific</td>
			<td>Surgi-M</td>
			<td>Temperature control</td>
		</tr>
		<tr>
			<td>Hot Bead sterilizer</td>
			<td>Germinator 500</td>
			<td>11503</td>
			<td>Sterilization of surgical instrument</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Covetrus</td>
			<td>29405</td>
			<td>Anesthesia</td>
		</tr>
		<tr>
			<td>Masson&#8217;s trichrome staining kit</td>
			<td>Thermoscientific</td>
			<td>87019</td>
			<td>Measurement of cardiac Fibrosis</td>
		</tr>
		<tr>
			<td>Micro Needle Holder</td>
			<td>FST</td>
			<td>12500-12</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Micro scissors</td>
			<td>FST</td>
			<td>15000-02</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Ophthalmic ointment</td>
			<td>Dechra</td>
			<td>Puralube Vet</td>
			<td>Sterile occular lubricant</td>
		</tr>
		<tr>
			<td>Scanning Gel</td>
			<td>Parker Laboratories</td>
			<td>Aquasonic 100</td>
			<td>Aqueous ultrasound transmission gel</td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>FST</td>
			<td>14060-11</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Small Animal Laryngoscope</td>
			<td>Penn-Century</td>
			<td>Model LS-2-M</td>
			<td>Illuminating the oropharynx</td>
		</tr>
		<tr>
			<td>Small animal ventilator</td>
			<td>Harvard apparatus</td>
			<td>557058</td>
			<td>Ventilator support</td>
		</tr>
		<tr>
			<td>Surgical light</td>
			<td>Cole parmer</td>
			<td>41723</td>
			<td>Illuminator Width (in): 7</td>
		</tr>
		<tr>
			<td>Vevo 3100 preclinical imaging platform</td>
			<td>Fujifilm</td>
			<td>VEVO 3100</td>
			<td>Echocardiography</td>
		</tr>
		<tr>
			<td>VevoLAB software</td>
			<td>Fujifilm</td>
			<td>VevoLAB 3.2.6</td>
			<td>Echocardiography data analysis</td>
		</tr>
	</tbody>
</table>

left coronary artery ligation: a surgical murine model of myocardial infarction

Ischemic heart disease and subsequent myocardial infarction (MI) is one of the leading causes of mortality in the United States and around the world. In order to explore the pathophysiological changes after myocardial infarction and design future treatments, research models of MI are required. Permanent ligation of the left coronary artery (LCA) in mice is a popular model to investigate cardiac function and ventricular remodeling post MI. Here we describe a less invasive, reliable, and reproducible surgical murine MI model by permanent ligation of the LCA. Our surgical model comprises of an easily reversible general anesthesia, endotracheal intubation that does not require a tracheotomy, and a thoracotomy. Electrocardiography and troponin measurement should be performed to ensure MI. Echocardiography at day 28 after MI will discern heart function and heart failure parameters. The degree of cardiac fibrosis can be evaluated by Masson's trichrome staining and cardiac MRI. This MI model is useful for studying the pathophysiological and immunological alterations after MI.

Figure 1 demonstrates the representative active ECG and respiration signals during the echocardiographic evaluation of sham (Figure 1A) and MI (Figure 1B) mice. Verification of active ECG and respiration signals are important before acquiring the echocardiographic data. Figure 2 shows echocardiographic measurement of cardiac functional parameters following 28 days after LCA ligation. <s...

Watch this Scientific Journal Video about Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction at JoVE.com

Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction

Presented here is a surgical procedure for permanent ligation of the left coronary artery in mice. This model can be used to investigate the pathophysiology and associated inflammatory response after myocardial infarction.

Ischemic heart disease and subsequent myocardial infarction (MI) is one of the leading causes of mortality in the United States and around the world. In ...

The surgical model permanent ligation of left artery in mice can be used to investigate the pathophysiology and associated inflammatory response after myocardial infarction. This method provides a reliable and producible mouse model of MI, which is easy, safe, and less invasive. To begin, preheat a bead sterilizer to 250 degrees Celsius and place autoclaved surgical instruments in it for a few minutes.Ensure the depth of anesthesia in the mouse by checking the response to a firm toe pinch. Weigh the mouse to estimate the dosage of the pre-operative analgesic drug buprenorphine and inject the drug intraperitoneally. Trim the fur on the left side of the thorax using an electric razor.After disinfecting the surgical site, place the mouse in the supine position on an inclined board. Secure the head and limbs of the mouse using an elastic band attached to the upper incisors and adhesive tape respectively. Apply sterile ophthalmic lubricant to the eyes to prevent dryness while under anesthesia.Open the jaw and gently pull the tongue out of the oral cavity. Identify the opening of the larynx by illuminating the oral pharynx using a laryngoscope. Cut off about 0.5 centimeters from a 24 gauge catheter needle and insert the blunt needle into the plastic shield.Direct the blunt needle with the plastic shield into the trachea. Take out the needle, leaving the plastic shield in the trachea. Set the ventilator to a respiratory rate of 137 beats per minute, optimized for the mice used in this study and tidal volume 0.18 closing capacity.Connect the respirator tubes to the catheter shield and confirm correct intubation by looking for a synchronized chest movement with the ventilator. Disconnect the respirator tube from the catheter shield and place the animal in the supine position on a preheated temperature controlled surgical board. Reconnect the mouse to the ventilator.After disinfecting the surgical site gently lift the skin using a pair of forceps and make a small cutaneous transverse incision along the line between the left pectoralis major and minor muscles using a pair of surgical scissors. Separate the underlying pectoralis muscles with forceps and dissecting scissors. After making an incision in the third intercostal space gently stretch the ribs apart using retractors to expose the left ventricle.Move the pericardial fat aside and locate the left coronary artery, which runs from the edge of the left atrium toward the apex of the heart. Pass an 8-0 nylon suture under the left coronary artery with the help of a needle holder. Legate the left coronary artery with a double knot followed by a second knot.Remove the retractors and insert a 22 gauge catheter needle into the chest cavity. Remove the needle, leaving the tip of the plastic shield in the thoracic cavity. Close the ribcage using a 4-0 nylon suture.Connect a syringe to the 22 gauge plastic shield and slowly remove excess air trapped in the thoracic cavity by gently pressing the chest to establish a negative air pressure. Remove the plastic shield. Switch off the isoflurane supply and place the mouse on the ventilator supplying oxygen.One spontaneous breathing of the mouse starts, switch off the ventilator. Keep the mouse under a heat lamp and monitor until it is awake. The animal should not be left unattended until it has recovered enough consciousness to maintain sternal recumbency.Monitor the mouse daily for any sign of pain or discomfort. Continue intraperitoneal injection of buprenorphine every 6 to 8 hours for an additional two days following the surgery. Active ECG and respiration signals were verified before acquiring the echocardiographic data.The echocardiographic measurement of cardiac functional parameters was noted 28 days after left coronary artery ligation. The M-mode images of the peroneal short axis view of SHAM and MI hearts were observed. The MI images showed defective heart wall movement following left coronary artery ligation.Indicators of heart failure, such as increased left ventricular mass, decreased ejection fraction, and decreased cardiac output were observed in the MI group as compared to the SHAM group. Masson's trichrome staining of the lower, middle, and upper ventricle sections showed increased collagen staining in the infarcted heart, indicating augmented fibrosis. In most cases, the artery is not feasible.However, ligating the myocardial tissue 2 to 4 millimeters below the edge of the left atrium results in efficient ligation of the artery.

Research

JoVE Journal

Medicine

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