Name: An Intact Pericardium Ischemic Rodent Model (Video) | JoVE Journal
Uploaded: 2021-09-02T14:00:00.000+00:00
Duration: 7 min 15 s
Description: Learn a modified coronary ligation technique for myocardial infarction modeling in mice that preserves the intact pericardium. This method enables evaluation of pericardial contents in cardiac repair and therapeutic targeting.

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Male and female C57BL/6J mice between 8-14 weeks of age were used for these experiments. This protocol has received ethical approval from the Animal Care Committee at the University of Calgary and follows all animal care guidelines.
1. Mouse preparation and surgery
<ol>
	<li>Sterilize surgical tools (via bead sterilizer or autoclave).</li>
	<li>Weigh mouse for presurgical weight and analgesic dose.</li>
	<li>Place the mouse in an induction box with 4% isoflurane and 800 mL/min of oxygen. Confirm the anesthetic plane by pinching the toes and observing the animal for lack of reflex.</li>
	<li>Inject analgesic subcutaneously (0.1 mg/kg of Buprenorphine) (see Table of Materials).</li>
	<li>Place the mouse on a heated surgical pad during surgery and maintain anesthesia with 3% isoflurane delivered via nose cone. Apply ophthalmic ointment to avoid dry eyes to each eye.</li>
	<li>Shave the hair from the chest and neck surgical areas.</li>
	<li>Restrain the paws of the mouse and position them on the surgical table.</li>
	<li>Intubate the mouse by inserting a smooth tipped 23 G catheter into the trachea through the mouth and the pharynx.
	<ol>
		<li>Ventilate the mouse following intubation with 2% isoflurane and 100% oxygen as a carrier gas using a commercial Ventilator (see Table of Materials) set at a rate of 110 breaths/min, a tidal volume of 250 &#181;L, and positive end-expiratory pressure (PEEP) of 4 mmHg.</li>
	</ol>
	</li>
	<li>Roll the mouse 30% on its right side to position the left side of the chest for surgery.</li>
	<li>Clean the surgical area with 3 alternating scrubs of 70% ethanol and betadine in a circular motion(seeTable of Materials). Place sterile surgical drapes around the surgical area.</li>
	<li>Make a 2-3 cm lateral incision in the skin of the chest to visualize the pectoralis muscles on the left side. Cut the pectoralis major and minor using a 1 cm incision from the midline outward to visualize the intercostal muscles between the third and fourth ribs. 
	NOTE: Care should be taken to avoid excess bleeding from the pectoralis muscle through cauterization of bleeding vessels.</li>
	<li>Make a 2 cm incision in the left intercostal muscle to introduce air (by passive air movement) into the chest cavity to allow the heart and lungs to fall away from the surgical incision. Further, expand the opening with the help of a cautery device (see Table of Materials) to incise the intercostal and prevent bleeding 
	NOTE: The ventilator should be temporarily stopped during the period of cauterization to avoid explosive reactions with oxygen. Care is taken not to damage the pericardial sac.</li>
	<li>Using retractors, retract the ribs to expose the heart.</li>
	<li>Observe the pericardium and the underlying heart under a stereomicroscope. 
	NOTE: The mouse pericardium is thin enough to visualize the vasculature of the heart.</li>
	<li>Gently place forceps on the surface of the pericardium to reduce its movement and that of the underlying heart.</li>
	<li>Visually landmark the left anterior descending (LAD) coronary artery by tracing its emergence from under the left appendage.</li>
	<li>Using the micro-needle driver, guide an appropriate suture (see Table of Materials) through the pericardium, under the LAD, with the suture emerging on the other side of the LAD and pericardium. Tie the suture to restrict the blood flow through the coronary artery and trim the excess suture with the help of scissors (Figure 1A). 
	NOTE: Upon restricting blood flow to the coronary artery, blanching of the anterior portion of the left ventricle should be visible. This procedure represents a permanent ligation model. However, a transient ligation approach with different ischemia periods could also be applied at this stage.</li>
	<li>Below the incision site within the sterile area, introduce a 24 G catheter percutaneously into the chest (remove the guide needle after entering the chest cavity). Then, close the ribs followed by muscle layers and skin using an appropriate suture (a taper needle for muscle, conventional cutting needle for skin).</li>
	<li>Once the chest is closed, evacuate the remaining air from the chest cavity via the 24 G catheter using gentle suction with a 3 mL syringe and chest compressions. Once the air is removed, withdraw the 24 G catheter.</li>
	<li>Reduce the isoflurane to 1%.</li>
	<li>Turn off the isoflurane while maintaining ventilation with oxygen to allow the mouse to recover from anesthesia. Once the animal shows signs of breathing independently, remove the 23 G tracheal tube from the mouth and place the mouse in a recovery cage to be monitored for resumption of normal breathing.</li>
	<li>Allow the mouse to recover in the cage with a portion of the cage placed on a warming pad to provide an external heat source.</li>
	<li>Provide maintenance injections of analgesic (Buprenorphine 0.1 mg/kg, subcutaneously) every 12 h for 72 h post-surgery.</li>
	<li>Monitor the health status of mice daily for 7 days, which includes evaluating incisions and animal discomfort. 
	&#8203;NOTE: Due to the invasiveness of this procedure (thoracotomy), the administration of antibiotics may be necessary.</li>
</ol>
2. Functional assessment of cardiac function by echocardiography (ECG)
<ol>
	<li>Induce and maintain the mouse under general anesthesia with 1.5-2% isoflurane and 800 mL/min of oxygen.</li>
	<li>Place mouse in a supine position on a heated stage platform and attach the paws to the ECG leads.</li>
	<li>Shave the chest of the mouse.</li>
	<li>Acquire echocardiography images using a 40 MHz linear transducer probe and contact gel and analyze with the appropriate software (see Table of Materials).</li>
	<li>Turn off the isoflurane and allow the mouse to recover on the heating platform before returning the cage to an active state. 
	&#8203;NOTE: Echocardiography assessment is non-invasive and thus can be performed longitudinally throughout the experiment to determine changes before and after coronary ligation.</li>
</ol>
3. Heart tissue collection for fibrosis staining
<ol>
	<li>Sacrifice the mice with inhalation of 100% CO2 and carefully dissect out the heart. 
	NOTE: Using scissors and forceps, this is achieved by cutting through the large vessels entering (vena cava, pulmonary vein) and exiting (pulmonary artery, aorta) the heart to release it from the circulatory system in the thoracic cavity.</li>
	<li>Fix the heart in 10% formalin for at least 24 h.</li>
	<li>Cut samples using a straight razor blade through the right ventricle, interventricular septum, and left ventricle, ensuring that the incision went through the center of the infarct zone. Samples are then sent to the core facility for paraffin embedding.</li>
	<li>Cut tissue sections of 5 &#181;m thickness with a microtome and place them on glass slides for staining.</li>
	<li>Deparaffinize using commercial xylene and graded alcohol washes (2x 99%, 1x 95%, 1x 70%) with deionized water, then rehydrate.</li>
	<li>Stain with 0.1% Sirius red in picric acid for 2 h at room temperature.</li>
	<li>Wash sections with 0.5% acetic acid for 3 min and rinse with 70% ethanol for 1 min.</li>
	<li>Dehydrate the sections using the reverse order of washes outlined in 3.4, with increasing and graded ethanol concentrations then xylene.</li>
	<li>Mount tissue sections with a mounting solution (see Table of Materials) for microscopic evaluation.</li>
</ol>
4. Flow cytometry of heart and pericardial cavity lavage
<ol>
	<li>Sacrifice the mice with inhalation of 100% CO2 to effect.</li>
	<li>Place the mouse on its back and fix the arms and legs to a surgical board using tape.</li>
	<li>Carefully open the left side (right side from the experimenter view) of the thoracic cavity, starting with cutting the diaphragm to about the midpoint and subsequently cutting through the outside ribs towards the sternum. 
	NOTE: Avoid nicking large blood vessels, particularly those that run parallel to the sternum.</li>
	<li>Retract the ribs using a hemostat to expose the underlying heart and pericardium. 
	NOTE: The pericardium is very fragile, so be sure not to catch it with scissors during the cutting.</li>
	<li>Using a PE-10 tubing (see Table of Materials) catheter inserted into the pericardial space near the junction of the left atrium and left ventricle, inject 100 &#181;L of sterile saline into the pericardial cavity.
	<ol>
		<li>Allow saline to pool and collect from the posterior side of the heart, being careful not to puncture or tear the pericardium in the process. Repeat this step twice and place lavage fluid on ice while processing the heart.</li>
	</ol>
	</li>
	<li>Excise the heart by cutting the major vessels (aorta, pulmonary artery, vein, and vena cava) entering and exiting the heart. Remove the right and left atria and weigh the ventricular heart tissue.</li>
	<li>Mince the tissue in small 1 mm2 pieces using scissors and place in 10 mL of digestion buffer containing 450 U/mL of collagenase I, 125 U/mL of collagenase XI, 60 U/mL of DNase I, and 60 U/mL of hyaluronidase in PBS for 1 h at 37 &#176;C on an orbital shaker.</li>
	<li>Pass heart tissue homogenates through a 70 &#181;m cell strainer (see Table of Materials) and spin down at 60 x g for 5 min at 4 &#176;C to remove cardiac parenchymal cells.</li>
	<li>Collect the supernatant, pass through a 40 &#181;m cell strainer (see Table of Materials) for a single cell suspension, and spin down at 400 x g for 5 min at 4 &#176;C to pellet the cells.</li>
	<li>Perform fragment crystallizable (Fc) receptor blocking and staining of cellular markers on pericardial and cardiac cells as previously described8.</li>
	<li>Run samples on a flow cytometer.</li>
</ol>
5. Labeling pericardial macrophage using the Intercostal Approach to the Pleural Space (ICAPS) method9
<ol>
	<li>Sterilize surgical tools (via bead sterilizer or autoclave) and spray 70% ethanol before commencing.</li>
	<li>Induce and maintain the mouse under general anesthesia with 1.5-2% isoflurane and 800 mL/min of oxygen. Confirm the anesthetic plane by pinching the toes and observing the animal for lack of reflex.</li>
	<li>Inject analgesic subcutaneously (Buprenorphine 0.1 mg/Kg).</li>
	<li>Place the mouse on a heated surgical pad during surgery.</li>
	<li>Shave the right anterolateral thoracic area.</li>
	<li>Clean the surgical area with ethanol and betadine.</li>
	<li>Make a 3 cm long incision in the skin, and with forceps expose the rib cage.</li>
	<li>Load 5 &#181;L of fluorescent beads (commercially available fluorescent microspheres, 1 &#181;m, see Table of Materials) and 45 &#181;L of saline into a PE-10 tubing syringe catheter with a beveled tip.</li>
	<li>Guide the catheter into the intercostal space as previously described9, slowly inject the bead solution and remove the catheter in one motion.</li>
	<li>Close the skin using staples. 
	NOTE: Staples are used in place of sutures to minimize potential re-opening of the incision.</li>
	<li>Turn off the isoflurane, place the mouse in the recovery cage and monitor for complications over the first 24 h.</li>
</ol>

<ol><li>Virani, S. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Heart+disease+and+stroke+statistics-2020+update%3A+A+report+from+the+American+Heart+Association%5BTitle%5D)+AND+%22Circulation%22%5BJournal%5D)">Heart disease and stroke statistics-2020 update: A report from the American Heart Association.</a> Circulation. 141, 139(2020).</li>
<li>Iismaa, S. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparative+regenerative+mechanisms+across+different+mammalian+tissues%5BTitle%5D)+AND+%22NPJ+Regenerative+Medicine%22%5BJournal%5D)">Comparative regenerative mechanisms across different mammalian tissues.</a> NPJ Regenerative Medicine. 3 (6), eCollection 2018 (2018).</li>
<li>Bayat, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Progressive+heart+failure+after+myocardial+infarction+in+mice%5BTitle%5D)+AND+%22Basic+Research+in+Cardiology%22%5BJournal%5D)">Progressive heart failure after myocardial infarction in mice.</a> Basic Research in Cardiology. 97 (3), 206-213 (2002).</li>
<li>Virag, J. A., Lust, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Coronary+artery+ligation+and+intramyocardial+injection+in+a+murine+model+of+infarction%5BTitle%5D)+AND+%22Journal+of+Visualized+Experiments%22%5BJournal%5D)">Coronary artery ligation and intramyocardial injection in a murine model of infarction.</a> Journal of Visualized Experiments. 52, 2581(2011).</li>
<li>De Villiers, C., Riley, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Mouse+models+of+myocardial+infarction%3A+comparing+permanent+ligation+and+ischaemia-reperfusion%5BTitle%5D)+AND+%22Disease+Models+%26+Mechanisms%22%5BJournal%5D)">Mouse models of myocardial infarction: comparing permanent ligation and ischaemia-reperfusion.</a> Disease Models & Mechanisms. 13 (11), (2020).</li>
<li>Borlaug, B. A., Reddy, Y. N. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+role+of+the+pericardium+in+heart+failure%3A+Implications+for+pathophysiology+and+treatment%5BTitle%5D)+AND+%22JACC+Heart+Failure%22%5BJournal%5D)">The role of the pericardium in heart failure: Implications for pathophysiology and treatment.</a> JACC Heart Failure. 7 (7), 574-585 (2019).</li>
<li>Pfaller, M. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+importance+of+the+pericardium+for+cardiac+biomechanics%3A+from+physiology+to+computational+modeling%5BTitle%5D)+AND+%22Biomechanics+and+Modeling+in+Mechanobiology%22%5BJournal%5D)">The importance of the pericardium for cardiac biomechanics: from physiology to computational modeling.</a> Biomechanics and Modeling in Mechanobiology. 18 (2), 503-529 (2019).</li>
<li>Deniset, J. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Gata6%28%2B%29+Pericardial+Cavity+Macrophages+Relocate+to+the+Injured+Heart+and+Prevent+Cardiac+Fibrosis%5BTitle%5D)+AND+%22Immunity%22%5BJournal%5D)">Gata6(+) Pericardial Cavity Macrophages Relocate to the Injured Heart and Prevent Cardiac Fibrosis.</a> Immunity. 51 (1), 131-140 (2019).</li>
<li>Weber, G. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Immune+targeting+of+the+pleural+space+by+intercostal+approach%5BTitle%5D)+AND+%22BMC+Pulmonary+Medicine%22%5BJournal%5D)">Immune targeting of the pleural space by intercostal approach.</a> BMC Pulmonary Medicine. 15, 14(2015).</li>
<li>Nakatani, T., Shinohara, H., Fukuo, Y., Morisawa, S., Matsuda, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pericardium+of+rodents%3A+pores+connect+the+pericardial+and+pleural+cavities%5BTitle%5D)+AND+%22The+Anatomical+Record%22%5BJournal%5D)">Pericardium of rodents: pores connect the pericardial and pleural cavities.</a> The Anatomical Record. 220, 132-137 (1988).</li>
<li>Tyberg, J. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+relationship+between+pericardial+pressure+and+right+atrial+pressure%3A+an+intraoperative+study%5BTitle%5D)+AND+%22Circulation%22%5BJournal%5D)">The relationship between pericardial pressure and right atrial pressure: an intraoperative study.</a> Circulation. 73, 428-432 (1986).</li>
<li>Hamilton, D. R., Sas, R., Semlacher, R. A., Kieser Prieur, T. M., Tyberg, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+relationship+between+left+and+right+pericardial+pressures+in+humans%3A+an+intraoperative+study%5BTitle%5D)+AND+%22The+Canadian+Journal+of+Cardiology%22%5BJournal%5D)">The relationship between left and right pericardial pressures in humans: an intraoperative study.</a> The Canadian Journal of Cardiology. 27, 346-350 (2011).</li>
<li>Park, D. S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Human+pericardial+proteoglycan+4+%28lubricin%29%3A+Implications+for+postcardiotomy+intrathoracic+adhesion+formation%5BTitle%5D)+AND+%22The+Journal+of+Thoracic+and+Cardiovascular+Surgery%22%5BJournal%5D)">Human pericardial proteoglycan 4 (lubricin): Implications for postcardiotomy intrathoracic adhesion formation.</a> The Journal of Thoracic and Cardiovascular Surgery. 156 (4), 1598-1608 (2018).</li>
</ol>

The authors have no conflicts to disclose.

Inducing an MI in a closed pericardium in rodents is unique and can have potentially significant applications. The procedure relies heavily on the surgeon&#39;s familiarity with the rodent model and rodent cardiac anatomy. Success is also dependent on the care given during three critical steps: intercostal muscle incision and rib retraction (Steps 1.11-1.13), creating the infarct (Step 1.17 ), and animal recovery (Steps 1.22-1.24).
The thoracotomy must be done diligently to avoid puncturing or...

To this day, cardiovascular disease (CVD) is recognized as the leading cause of death globally, resulting in a significant financial burden and reduction in patient quality of life1. Coronary artery disease (CAD) is a sub-type of CVD and plays an essential role in the development of myocardial infarction (MI), which is a chief contributor to mortality. By definition, MI results from irreversible injury to the myocardial tissue due to prolonged conditions of ischemia and hypoxia. Myocardial tissue lacks regeneration capacity, so injuries are permanent and result in the replacement of heart muscle with a fibrotic scar that can be initially protective but ultimately contributes to adverse cardiac remodeling and eventual heart failure2.
Although the management of patients with CAD has dramatically improved over the past few decades, chronic heart failure (CHF) secondary to ischemia affects many patients worldwide. For preventing and managing this epidemic, it is necessary to understand the underlying mechanisms more extensively and develop new therapeutic approaches. Moreover, past findings highlight the limitations of systemic therapy and the necessity of developing precise alternatives. Given investigating the molecular sequelae of MI in humans is affected by the ability to access infarcted tissue, animal models that recapitulate the characteristics and development of human MI and CHF related to CVD are indispensable.
As ideal animal models closely resemble a human disorder for structural and functional characteristics, disease etiology should guide their conception. In CAD, it is the chronic atherosclerotic stenosis of coronary arteries or acute thrombotic occlusion. Different methods have been developed and applied in various species of laboratory animals to induce coronary artery narrowing or occlusion. Such strategies can be broadly classified into two groups: (1) mechanical manipulation of a coronary artery to induce an MI and (2) expediting atherosclerosis to facilitate coronary narrowing leading to an MI. The first strategy usually involves either the ligation of a coronary artery or the placement of a stent within the artery. The second approach tends to rely on modifying the animal&#39;s diet to include high fat/cholesterol food. Some of the limitations of this latter approach include the lack of control on the timing and site of coronary occlusions.
In contrast, the surgical induction of MI or ischemia in an animal model has several advantages, such as location, precise timing, and extent of the coronary event, leading to more reproducible results. The most widely used method is surgical ligation of the left anterior descending coronary artery (LAD). Such models recapitulate human responses to acute ischemic injury, as well as the progression to CHF3. Initially developed in larger animals, LAD surgery on small animals such as rodents has become more feasible with advancements in technology4. In establishing such models, mice have been favored for various reasons, including their relative availability, low expense in housing, and their capacity for genetic manipulation.
Contemporary surgical models of ischemic heart disease using LAD occlusion require the researcher to open the pericardium to temporarily or permanently ligate the artery5. Such strategies result in the disruption of the pericardial space, which plays an essentially mechanical and lubricating function to ensure proper cardiac function. Another disadvantage of opening the pericardium is losing the animal&#39;s native pericardial fluid with its various cellular and protein components6,7. In response, a method to induce MI while keeping the pericardium intact was developed by us. In addition to minimizing the perturbation of this homeostatic environment, this approach allows for tagging and tracing specific cells after causing an MI. In addition, this approach better represents myocardial ischemic injury in the human setting.

<table><tbody><tr><td>Steri-350 Bead Sterilizer</td><td>Inotech</td><td>NC9449759</td><td></td></tr><tr><td>10% Formalin</td><td>Millipore Sigma</td><td>HT501128-4L</td><td></td></tr><tr><td>40 &amp;micro;m Cell strainer</td><td>VWR</td><td>CA21008-949</td><td>Falcon, 352340</td></tr><tr><td>70 &amp;micro;m Cell strainer</td><td>VWR</td><td>CA21008-952</td><td>Falcon, 352350</td></tr><tr><td>ACK Lysis Buffer</td><td>Thermo Fisher</td><td>A1049201</td><td></td></tr><tr><td>BD Insyte-W Catheter Needle 24 G X 3/4&quot;</td><td>CDMV Inc</td><td>108778</td><td></td></tr><tr><td>Betadine (10% povidone-iodine topical solution)</td><td>CDMV Inc</td><td>104826</td><td></td></tr><tr><td>Blunt Forceps</td><td>Fine Science Tools</td><td>FST 11000-12</td><td></td></tr><tr><td>BNP Ophthalmic Ointment</td><td>CDMV Inc</td><td>17909</td><td></td></tr><tr><td>Castroviejo Needle Driver</td><td>Fine Science Tools</td><td>FST 12061-01</td><td></td></tr><tr><td>Centrifuge 5810R</td><td>Eppendorf</td><td>22625101</td><td></td></tr><tr><td>Collagenase I</td><td>Millipore Sigma</td><td>SCR103</td><td></td></tr><tr><td>Collagenase XI</td><td>Millipore Sigma</td><td>C7657</td><td></td></tr><tr><td>Covidien 5-0 Polysorb Suture - CV-11 taper needle</td><td>Medtronic Canada</td><td>GL-890</td><td></td></tr><tr><td>Covidien 5-0 Polysorb Suture - PC-13 cutting needle</td><td>Medtronic Canada</td><td>SL-1659</td><td></td></tr><tr><td>Curved Blunt Forceps</td><td>Fine Science Tools</td><td>FST 11009-13</td><td></td></tr><tr><td>Dako Mounting Medium</td><td>Agilen</td><td>CS70330-2</td><td></td></tr><tr><td>DNase I</td><td>Millipore Sigma</td><td>11284932001</td><td></td></tr><tr><td>Ethanol, 100%</td><td>Millipore Sigma</td><td>MFCD00003568</td><td></td></tr><tr><td>Ethicon 8-0 Ethilon Suture - BV-130-4 taper needle</td><td>Johnson &amp;amp; Johnson Inc.</td><td>2815G</td><td></td></tr><tr><td>Fiber-Optic Light</td><td>Nikon</td><td>2208502</td><td></td></tr><tr><td>Fine Forceps</td><td>Fine Science Tools</td><td>FST 11150-10</td><td></td></tr><tr><td>Fluoresbrite&amp;reg; YG Carboxylate Microspheres 1.00 &amp;micro;m</td><td>Polysciences, Inc.</td><td>15702</td><td></td></tr><tr><td>Geiger Thermal Cautery Unit</td><td>World Precision Instruments</td><td>501293</td><td>Model 150-ST</td></tr><tr><td>Hyaluronidase</td><td>Millipore Sigma</td><td>H4272</td><td></td></tr><tr><td>Isofluorane Vaporizer</td><td>Harvard Apparatus</td><td>75-0951</td><td></td></tr><tr><td>Isoflurane USP, 250 mL</td><td>CDMV Inc</td><td>108737</td><td></td></tr><tr><td>Magnetic Fixator Retraction System</td><td>Fine Science Tools</td><td>18200-20</td><td></td></tr><tr><td>MX550D- 40 MHz probe</td><td>Fujifilm- Visual Sonics</td><td></td><td></td></tr><tr><td>Needle Driver</td><td>Fine Science Tools</td><td>FST 12002-12</td><td></td></tr><tr><td>PE-10 Tubing</td><td>Braintree Scienctific, Inc.</td><td>PE10 50 FT</td><td></td></tr><tr><td>Scissors</td><td>Fine Science Tools</td><td>FST 14184-09</td><td></td></tr><tr><td>SMZ-1B Stereo Microscope</td><td>Nikon</td><td>SMZ1-PS</td><td></td></tr><tr><td>VentElite Small Animal Ventilator</td><td>Harvard Apparatus</td><td>55-7040</td><td></td></tr><tr><td>Vetergesic (10 mL, 0.3mg/mL buprenorphine))</td><td>CDMV Inc</td><td>124918</td><td>controlled drug</td></tr><tr><td>Vevo 2100 Software</td><td>Fujifilm-Visual Sonics</td><td></td><td></td></tr></tbody></table>

an intact pericardium ischemic rodent model

An Intact Pericardium Ischemic Rodent Model

This protocol has shown that the pericardium and its contents play an essential anti-fibrotic role in the ischemic rodent model (coronary ligation to induce myocardial injury). The majority of pre-clinical myocardial infarction models require the disruption of pericardial integrity with loss of the homeostatic cellular milieu. However, recently a methodology has been developed by us to induce myocardial infarction, which minimizes pericardial damage and retains the heart&#39;s resident immune cell population. An improved cardiac functional recovery in mice with an intact pericardial space following coronary ligation has been observed. This method provides an opportunity to study inflammatory responses in the pericardial space following myocardial infarction. Further development of the labeling techniques can be combined with this model to understand the fate and function of pericardial immune cells in regulating the inflammatory mechanisms that drive remodeling in the heart, including fibrosis.

This modified coronary ligation model has been optimized to achieve reproducibility and animal survival. However, due to the significant injury induced in the heart, some expected intra-operative and post-operative mortality are associated with the procedure. The standard mortality is typically higher in males (~25-35%) than in females (~ 10-15%).
Successful induction of an MI with the modified coronary ligation should be evident by changes in the heart's functional parameters and structural f...

This protocol outlines the steps for inducing myocardial infarction in mice while preserving the pericardium and its contents.

This protocol has shown that the pericardium and its contents play an essential anti-fibrotic role in the ischemic rodent model (coronary ligation to ...

an-intact-pericardium-ischemic-rodent-model

Research

JoVE Journal

Medicine

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

Acute Myocardial Infarction in Rats

Surgical trauma induces an inflammatory response. Cytokines and endogenous ligands are known to modulate myocardial infarct size following ischemia and reperfusion. We present a modified closed-chest model of murine ischemia and reperfusion using hanging weights to minimize effects of thoracotomy.

A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion

We introduce a surgical method to induce experimental ischemia/reperfusion (I/R) injury to simulate myocardial infarction (MI) in mouse models that allows for more clarity in positioning of the ligation on the left anterior descending artery (LAD) to increase the reproducibility of MI experiments in mice.

A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery

The goal of this protocol to assess myocardial stunning following ischemic cardioplegic arrest in rodents.

Murine Isolated Heart Model of Myocardial Stunning Associated with Cardioplegic Arrest

Isolated working heart models can be used to measure the effect of loading conditions, heart rate, and medications on myocardial performance and oxygen consumption. We describe methods for preparation of a rodent left heart working model that permits study of systolic and diastolic performance and oxygen consumption under various conditions.

Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption

During murine myocardial ischemia/reperfusion surgery, correct placement of the occluding ligature is typically confirmed by visible observation of myocardial pallor. Herein, a method of electrocardiographically confirming ischemia and reperfusion, to supplement observed myocardial pallor, is demonstrated in male C57Bl/6 mice.

Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography

Herein we describe a surgical procedure showing how to achieve permanent ligation of the left-anterior descending coronary artery in mice. This model is of high relevance to investigate the pathophysiology of myocardial infarction and the concomitant biological processes.

Murine Myocardial Infarction Model using Permanent Ligation of Left Anterior Descending Coronary Artery

Myocardial ischemia-reperfusion model of rat heart is improved by using a self-made retractor, polyvinyl chloride tube, and a unique knotting method. Electrocardiogram, triphenyltetrazolium chloride and histological staining, and percent survival analysis results showed that the improved model group has higher success and survival rates than the already existing model group.

Improved Rodent Model of Myocardial Ischemia and Reperfusion Injury

The present study demonstrates a highly reproducible animal model of acute regional myocardial ischemia and reperfusion injury in rabbits using a left mini-thoracotomy for survival cases or a midline sternotomy for non-survival cases.

Model of Ischemia and Reperfusion Injury in Rabbits

A method of gene transfer for the treatment of ischemic heart failure is described using a swine model of myocardial infarction. Our simple and reproducible method enables us to readily evaluate the efficacy of various gene transfers with a very simple and reproducible way.

Gene Transfer for Ischemic Heart Failure in a Preclinical Model

Learn a modified coronary ligation technique for myocardial infarction modeling in mice that preserves the intact pericardium. This method enables evaluation of pericardial contents in cardiac repair and therapeutic targeting.

An Intact Pericardium Ischemic Rodent Model

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