This article details the procedure of apical resection in neonatal mice, focusing on the role of cardiac macrophages in heart repair. The study highlights the regenerative capabilities of neonatal cardiac macrophages and their potential for restoring cardiac function in adults.
Apical resection of a neonatal mouse is a procedure to remove the left ventricular apex of the heart. The resulting injury activates neonatal cardiac macrophages that promote cellular processes for cardiac repair. However, this regenerative ability becomes limited in adulthood, leading to heart failure. Transplanting neonatal cardiac macrophages into the adult heart can restore cardiac function.
To begin, place a neonatal mouse on ice to induce hypothermia that numbs the mouse. Transfer and prep the unconscious mouse on a surgical platform. Now, under a stereoscope, horizontally incise the left side of the chest and separate the underlying muscles to visualize the heart.
Apply pressure on the chest and abdomen to exteriorize the heart. Carefully cut off the ventricular apex tissue till bleeding exposes the left ventricular chamber. Using a cotton swab, press the heart back into the chest cavity. Suture the incised chest wall. Apply tissue glue to join the skin. Subsequently, transfer the mouse to a heating blanket to stop hypothermia. Then, shift the operated neonatal mouse to its mother's cage for a speedy recovery.
Following apical resection, the resident cardiac macrophages accumulate in the injured site. Subsequently, these macrophages can be isolated for transplantation into the adult heart.
Begin by pre-cooling the bronze operating platform overnight at minus 20 degrees Celsius. Take the anesthetized mouse out of the icebox and put it on the platform. Anchor the mouse in a supine position using medical adhesive tape. Put the operating platform with the mouse under a stereoscope, and disinfect the mouse chest using a prep pad soaked with betadine and 70% alcohol.
Incise the skin with a 1-centimeter cut at the fourth intercostal area of the chest cavity, and separate the intercostal muscles using microsurgical scissors until the heart is accessed. Alternately press the chest and abdomen with the help of two forceps until the heart is exteriorized out of the chest, without any mechanical damage.
Set the ribs below and above the small incision as a natural fixation to immobilize the heart. Locate the apex of the left ventricle and cut a 1-millimeter diameter of ventricular apex tissue using iridectomy scissors. Confirm that the left ventricular chamber is exposed and begins oozing.
Gently press the heart back into the chest cavity using a cotton swab. Suture the muscles, ribs, and skin using 8-0 proline sutures, and clean the mouse thoroughly after the operation. Transfer the mouse from the operating platform to a 37-degree heating blanket to warm up the body immediately after the operation.
Confirm anabiosis of the mouse by observing for the signs of spontaneous respiration restoration, skin color change from pale to pink, and movement of limbs. Take the operated mouse back to its mother, once it has recovered. Mingle the operated mouse and its mother's nesting materials if necessary.
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