A Standardized Pig to Macaque Heterotopic Heart Xenotransplantation Model

The research is establishing a standard heterotopic xenotransplantation model to study rejection or be in consistency with orthotopic models, but easier operation. Small and large animal models, brain-dead recipient transplants, and primate recipients remain the key research models. To begin, scrub the shaved areas of an anesthetized donor thoroughly with povidone iodine.

Make a midline abdominal incision with a number 23 surgical blade, approximately 12 to 15 centimeters in length. Use electrocautery to sequentially dissect through the superficial fascia, linea alba, transversalis fascia, subperitoneal fascia, including extraperitoneal fat. And finally, incise the parietal peritoneum to access the abdominal cavity.

Explore the abdominal cavity to assess for any adhesions between the intestines and the abdominal wall. If adhesions are present, carefully dissect them using electrocautery to minimize tissue injury and reduce the risk of postoperative mechanical bowel obstruction. Then carefully dissect the surrounding tissues from the abdominal aorta and inferior vena cava to minimize vascular injury and bleeding.

Expose the abdominal aorta and inferior vena cava between the origins of the renal arteries and the iliac artery bifurcation as fully as possible. Preserve the inferior mesenteric artery and its vein during dissection. Meticulously preserve all lumbar branches.

To procure the donor heart, perform a midline sternotomy to access the thoracic cavity. Carefully divide the donor's sternum using a Lebsche sternum knife. After exposing the thoracic cavity, incise the pericardium and meticulously dissect to separate the ascending aorta and main pulmonary artery.

Place a 4-0 purse-string suture at the aortic root, and insert a single-use antegrade cardioplegia cannula. Sequentially clamp the superior and inferior vena cava, followed by cross-clamping the ascending aorta. Immediately after cross-clamping, incise the pulmonary veins and inferior vena cava to decompress the heart, ensuring incisions are large enough for drainage.

Immediately immerse the heart in sterile ice-cold saline to induce hypothermia between 0 to 4 degrees Celsius. Suction the pericardial cavity to evacuate the residual blood. Initially perfuse the donor heart with 30 milliliters per kilogram body weight of HTK solution.

Gently elevate the heart and sequentially transect the inferior vena cava and pulmonary veins using surgical scissors. Sequentially incise the left atrium, pulmonary artery, aorta, and superior vena cava, ensuring clear margins and tissue integrity. Immediately immerse the explanted heart in ice-cold saline for preservation.

Perfuse the donor heart with University of Wisconsin solution at 30 milliliters per kilogram for superior myocardial protection. To implant the donor heart, securely close the donor superior vena cava, inferior vena cava, and pulmonary vein orifices of the left atrium using 4-0 prolene sutures. Place a DeBakey atraumatic tangential clamp on the recipient's inferior vena cava.

Then using a double-armed 5-0 prolene suture, begin anastomosis at the 12 o'clock position, inserting one needle from inside to outside on the recipient vessel. Insert one needle from the outer wall of the donor artery to the lumen, then insert from the outer wall of the recipient inferior vena cava to the lumen. Continue with continuous suturing, and tie a knot after completing the anastomosis.

Partially clamp the recipient abdominal aorta using a DeBakey atraumatic tangential clamp. Create a longitudinal incision slightly larger than the donor aorta. Anastomose the donor aorta to the recipient abdominal aorta using the same technique.

Release the DeBakey atraumatic tangential clamp to allow arterial de-airing. And finally, tie a knot. Place a negative-pressure drainage tube in the abdominal cavity to prevent fluid accumulation and monitor for hemorrhage.

Close the abdominal wall and layers using 3-O absorbable sutures for fascia and subcutaneous tissue. A reproducible pig-to-macaque heterotopic heart xenotransplantation model was successfully established through a series of surgical steps, culminating in the placement of the donor heart into the recipient's abdominal cavity. Postoperative echocardiographic evaluation confirmed that the donor heart resumed contractual activity with preserved systolic and diastolic function.

The protocol is optimized for monkeys, providing access specific at the patients compared to bamboo-based transplantation techniques.