A Modified Simple Method for Induction of Myocardial Infarction in Mice

This report presents a unique approach for the induction of myocardial infarction in mice. The current method is easy, time-saving, and it uses the surgical tubes and equipment found readily in most laboratories. The establishment of myocardial infarction models provides a premise for investigating the past mechanisms of post-MI remodeling, and variation of novel therapeutics.

Apply the depilatory cream to the mouse chest, and wait for one minute. Then gently wipe off the depilatory cream and hair with wet gauze. Secure the mouse on a surgery platform in the supine position.

Disinfect the surgical area as described in the text. Then place a sterile drape around the disinfected area. Make a 0.5 centimeter skin cut along the line connecting the xiphoid and armpit, and bluntly separate the pectoral major and pectoral minor muscles using forceps.

Open the fourth intercostal space using a Micro-Mosquito hemostat. Externalize the heart by pushing it toward the fourth intercostal space with the index finger of the left hand. Secure the heart with the left hand and ligate the left anterior descending branch with a 6/0 suture three millimeters from its origin.

Place the heart back into the thoracic cavity quickly. Evacuate the air out of the thoracic cavity by gently pressing on the chest cavity. For post-operative pain management, inject buprenorphine subcutaneously every four to six hours for up to seventy-two hours post-surgery.

Place the mouse on a heating pad to recover from the anesthesia. Secure the euthanized mouse on the surgery platform in the supine position. Make a ventral incision of approximately three to four centimeters in the upper abdomen.

Cut off the ribs from both sides of the thorax cavity, and then remove the diaphragm. Perfuse the heart with 10 milliliters of cold four degree celsius 1X PBS through intraventricular injection. Then collect the heart by cutting off the aortic root, and immediately storing it at minus 80 degrees Celsius.

Slice the frozen heart into one millimeter thick sections on ice using razor blades. Incubate the prepared heart slices in 1%TTC solution dissolved in one 1X PBS at 37 degrees Celsius for 10 to 15 minutes. Then photograph the slices using a digital camera.

Following coronary artery ligation, TTC staining analysis indicated successful induction of myocardial infarction, and temporal changes of post-MI scar size. Survival analysis results showed overt mortality within seven days after MI in male and female C57BL/6J mice. Ventricular rupture was a common reason for post-MI death.

Post-MI echocardiographic assessment demonstrated successful induction of contractile dysfunction and ventricular remodeling. When attempting to externalize the heart, don’t press the chest cavity firstly, and following our resistance, indicates a need to adjust the direction against the weighted praise. Following this procedure, intramyocardial injection of viral vectors or cells can be performed to test the efficacy of gene therapies or cell therapies in heart disease matters.