"Pig heart" for "human heart", a crazy attempt at xenotransplantation

The University of Maryland Medical Center performed a special organ transplant in which a genetically modified pig heart was transplanted for the first time into a patient with advanced heart disease; the patient did not experience severe rejection and the pig heart began to function normally. This is the first successful transplantation of a genetically modified porcine heart into a patient in humans, which has attracted widespread public and media attention and discussion.

"Pig heart" for "human heart", a crazy attempt at xenotransplantation

According to CCTV news, the University of Maryland Medical Center released news on the 9th that the patient who received a pig heart transplant at the center died on the 8th, and it is not clear the exact cause of death. This particular transplant is the first of its kind in the world, and the patient survived for about two months after the operation.

In fact, xenotransplantation is not a recent novelty, its history can be traced back to more than three hundred years ago, which is full of many contradictions such as bravery and fanaticism, deception and ignorance, and finally gradually on the right path of science.

1. Early madness

In June 1667, a 15-year-old male patient developed a severe fever due to an unknown infection, and doctors treated him with the then-popular bloodletting therapy, which resulted in a severe lack of blood in his body. Dennis injected fresh lamb's blood into the patient's vein, and to his surprise, his body returned to normal. Doctors in other European countries followed suit, but soon after, Denis' patient died after repeated injections of lamb's blood, which directly led to the French government's explicit ban on blood transfusions in 1670, followed by Germany, England and other European countries.

"Pig heart" for "human heart", a crazy attempt at xenotransplantation

2. Back to science

The first scientists to perform allogeneic heart transplants were not universally known; in 1963, American physician James Hardy successfully performed the first human lung transplant, although the patient survived for only 18 days. Inspired by the results of the Keith Remtsma trial, Hardy performed the first human heart transplant in 1964, and the patient died less than two hours after the operation due to severe immune rejection. Several more xenogeneic heart transplants were performed by doctors with donors such as chimpanzees, baboons, sheep and pigs most of the patients survived no more than 1 day.

Most of these early allogeneic organ transplants were a rational and scientific exploration of unfortunate patients in the face of organ shortages and serious conditions. Although all of these patients eventually escaped their fate, they gave their lives to bring allogeneic organ transplant research into the right path of science.

3. Real development

"Pig heart" for "human heart", a crazy attempt at xenotransplantation

After long medical experiments and tragic costs, these experimental allogeneic transplants have increasingly awakened scientists to the fact that immune rejection remains the greatest obstacle to organ transplantation and is much greater between allogeneic organs than between homologous allogeneic organs. Immune rejection has become a problem that must be addressed.

Immunosuppression allows the patient's organism to accommodate foreign grafts by reducing the sensitivity of the immune system, making organ transplantation the ultimate means of saving the lives of patients with organ failure. For xenotransplantation to be successful, immunosuppressants alone are no longer enough. Scientists suddenly have a bright idea that if the cells of organ donor animals are modified to be close to human cells using genetic modification techniques, they can be expected to escape the attack of the human immune system.

Pigs have been chosen by scientists as the leading representative of allogeneic organ donor animals because of their similarity to human organ mechanisms, functions and metabolic characteristics, as well as their ability to reproduce, ease of husbandry and lack of ethical controversy faced by primates

Concluding remarks

On January 10, 2022, the world watched a breaking scientific news that three days earlier, surgeons at the University of Maryland Medical Center performed a genetically modified porcine heart transplant on a patient with advanced heart disease, and the patient is now doing well post-operatively with detectable normal heartbeat, pulse and blood pressure, and no significant rejection.

With the world's first porcine heart xenotransplantation clinical trial, it marks the beginning of a new era of xenotransplantation. It is expected that more xenotransplantation clinical trials will soon be conducted in the next few years, which is expected to bring new hope to a large number of critically ill patients who lack human-derived organ donors and have no other treatment options. When hearts can be interchanged between animals, the length of human life will become longer and longer, and we expect that day to come to bring hope to more heart patients.

(Reference Southern Weekend)