Today, medical and mass media at home and abroad are heatedly discussing a piece of news: American doctors transplant pig hearts into the human body for the first time.
Image source: Reference message @ Weibo
Surgery, which once appeared in science fiction, became a reality. While many onlookers were amazed, there were two very different professional voices. Some people are excited, calling it a great advance in human medicine; some people question it, thinking that it is an adventurous disregard for the interests of patients.
What is the story behind the operation?
A heart patient in desperate need of life
The patient who received a swine heart transplant was a 57-year-old man named David Bennett. In public information, we can't see what kind of disease he has, only that he is a chronic heart patient. His heart lost basic function and recurrent arrhythmias to the point of unsustainability. Regaining a healthy heart will keep Bennett alive.
The traditional source of these life-saving organs is posthumous donations by volunteers.
The U.S. completed almost 40,000 organ transplants last year, but in the face of greater demand, that number is a drop in the bucket. Bennett is not at the top of the official organ waiting system. Maybe there are people who are more serious than him, maybe he is in such poor physical condition that it is difficult for the system to regain health even if transplanted, or maybe there are other reasons... In short, the doors of the conventional route were closed.
In addition to donation, human organ cloning is also a path that has been considered, but it is also difficult to develop because of major ethical questions. It seems that the only way to change one's life is to focus on other animals.
Pig heart transplantation is not a whim
Using animal organs to meet human needs is not an idea that exists today. The first attempts were made in the 1960s. As the trial progressed, among the many alternative animals, pigs stood out as the most dominant source of xeno organs.
Why Pigs? Pigs are not far from human relatives, there are not many differences in organs; pigs are similar in size to humans, and the size of organs is the same; pigs are meat animals, and organ harvesting can continue to be used for meat, and animal protection organizations will not have much opposition...
CRISPR pork for transplantation tastes good
Image source: statnews
Of course, xenotransplantation did not develop to where it is today. It is necessary to let the organs of pigs survive in the human body, play a function, and not be killed by the rejection reaction, and they can only come step by step. From simple structures, partially active cells to intact organs. The more complex the structure of the organ, the more advanced technical support.
The technology behind the 9-hour procedure
On December 31, the FDA approved an emergency authorization for Bennett's surgery, which was performed at the Maryland Medical College on January 7 from 8:30 a.m. to 5:30 p.m. local time.
The pig heart used for transplantation is provided by Revivicor, a company that specializes in breeding gene-edited pigs for organ transplantation. In order to adapt to the human body, the heart has undergone a "makeover" of genetically modified technology. 3 pigs' genes were knocked out to avoid immediate immune rejection, 1 gene was knocked out to prevent the pig heart tissue from continuing to grow, and 6 human genes were transferred to the pig heart to prevent human blood from clotting in the pig heart and reduce the risk of immune rejection.
By the end of the operation, the pig's heart had already begun to beat in Bennett's chest. In addition to this special pig heart, a new anti-immune rejection drug will also be used after surgery.
The transplant team that completes the surgery
Image credit: medscape
The great controversy that followed
This is indeed an extraordinary journey of life saving, and advanced science and technology have brought new hope for survival.
But there is also great controversy. Some doctors thought the surgery was too radical and "crazy" and questioned the ethics committee's decision.
Indeed, before this operation, the large organ transplantation of pigs was still in the animal testing stage, and there were records of pig heart transplantation to baboons. Other pig organs, only 3 months ago the New York team performed a pig kidney human transplant, but at that time the transplant was the brain death of cerebral hemorrhage, transplantation was observed for several days to obtain preliminary data before stopping.
Now it is used in living people at once, or more complicated than the kidneys, and it is necessary to knock out the pig heart that transfers more genes, and it is indeed a big step. Is it the best choice? Or is it for bright data and "grades"? It's hard to say it all at once.
Maybe it's the first shot fired in the darkness of the transplant dilemma, or it's going to push xenotransplantation into the dark.
At this moment, the pig heart has been beating normally in Bennett's body for 75 hours. In the coming days, weeks, and months, the eyes of heart surgeons, heart patients and their families, xenotransplantation research companies, and even everyone around the world will be on this. Good luck to Bennett.
A small heart that carries too much too much.
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