In a recent push, we explained that organ transplantation and scientists’
A few days ago, there was a news about "pig 3.0" organ transplantation technology, which brought xenotransplantation into the public eye again:
what? Can pigs be used for organ transplants?
Kids, you must have many small question marks:
Why can't people use pigs?
If there is a pig's heart or something in your body, it sounds too psychedelic, right?
Why do we have to use a pig's heart?
In fact, the psychedelic operation of organ transplantation between species as early as
Why did you think of using organs from other animals for organ transplants?
The biggest problem with human-to-human organ transplantation is that there will be
Human beings are already so dangerous. If transplanting animal organs to humans is also called
But there is one of the most serious problems in human-to-human transplantation:
Taking my country as an example, the number of organ donations in 2018 reached 6,302, which is already the second highest level in the world, but the number of organ transplant operations has reached 20,000.
In addition, there are countless families waiting for organ transplants. For example, the Hong Kong Department of Health's appeal for organ donation mentioned that "more than two thousand patients every day" are waiting for organ donations.
Therefore, in recent years, scientists have turned their attention to xenotransplantation: the problem of the number of animals can be solved.
Wait, why is it "again"?
In fact, the history of xenotransplantation is as long as that of human-to-human organ transplantation.
The earliest record is that in 1682, a Russian nobleman was injured in battle, and his skull was missing. Surgeon Job Janszoon van Meekeren gave him a block.
最早的记录是在1682年，一名俄罗斯贵族在战斗中受伤，头骨丢失。外科医生乔布斯（Janszoon van Meekeren）给了他一个障碍。
The Christian church at that time was frightened when he knew it: "This man has a part of his head as a dog! Then he can never be a Christian!" But when the pious nobleman wanted to take it out again, he found that the wound had healed. Even the effect is not bad.
In the dreamy 17th century, there were more magical operations.
French doctor Jean-Baptiste Denys tried
In the 19th century, there were more types of xenogeneic organ transplantation-sheep's urethra, rabbit eyes, frog skin... Although some people say that their transplantation was successful, the skin structure is actually far more than they thought. To be complicated, for example, there are multiple layers of cells under the skin and densely covered with various blood vessels and nerves, and direct attachment cannot be transplanted.
By the beginning of the 20th century, with the invention of Alexis Carrel
In 1905, Princeteau tried to put a piece of
Later, some people tried to use the kidneys of pigs and sheep for transplantation, but the patients all appeared after transplantation.
Why did these attempts fail?
We mentioned earlier that human-to-human organ transplantation has the problem of immune transplant rejection. There are more problems in xenotransplantation, and the uncontrollability is more obvious. There are three main dangers that are relatively clear.
Another hazard is because
There is another less obvious threat, which is
In addition, there may be many problems: for example, different animals
This is even more unknown.
But scientists are the kind of people who discover problems, put forward hypotheses, and solve problems. Since there are so many obstacles, we must always find a way to overcome them.
Scientists set their sights on the chimpanzees who are closest to people.
We always say that people are changed from monkeys, but in fact, the statement is not exact, it should be
The chimpanzee and our common ancestor are the closest, about
Chimpanzee: I am co-authored with you and I am forced to donate organs?
(Source: Wikipedia | Aaron Logan)
As early as 1964, six patients with uremia or severe renal failure had undergone
After that, scientists also conducted several kidney transplant experiments of chimpanzees or baboons, but the results were not satisfactory. The patient's survival time was only extended by a few weeks.
In addition to the kidney, many doctors have tried to use the heart of a chimpanzee or baboon for organ transplantation, but the patient is very weak, and the heart of the chimpanzee or baboon has insufficient blood supply capacity, and even if the transplant is successful, there will be huge immunity. Rejection, after these operations are over
Although these attempts were not successful, some experiments have actually promoted
For example, in 1983, Leonard Bailey received a baby patient with congenital heart disease, but there were almost no baby organ donations, so Leonard used a baboon heart. The operation was successful, but because of immune rejection, the baby died 20 days later.
As chimpanzees have become an endangered species (of course not because of organ transplants), and the similarities between chimpanzees and humans have caused huge ethical issues, chimpanzees are no longer allowed to be used for such operations and research.
After all, according to the demand for human organs, chimpanzees can become extinct in a few years.
A door was closed, and the scientist opened another window, which seemed to be an advanced French window.
They set their sights on
The organ size of pigs is similar to that of humans, and the risk of infectious diseases is relatively low. Compared with chimpanzees and baboons, the number of pigs is quite sufficient, so there is no need to worry about the number.
But compared with chimpanzees, pigs have a longer common ancestor with humans, about
When the scientist was frustrated,
We can solve the problems of immune rejection, uncontrolled blood coagulation, endogenous virus and so on through gene editing through known key gene loci of the immune system of pigs and humans.
But it’s easy to say, but not easy to implement: related to immunity and coagulation
This is destined to be another protracted battle, and it has been fought for decades.
Scientists are constantly trying to transplant gene-edited pig organs to
In the beginning, the α1,3-galactosyltransferase gene was knocked out (the first period, GTKO pig), which reduced the response of T cells to pig cells; then the complement response was further controlled (the second period, CRP pig); To control the expression of thrombomodulin gene (the third period), the survival time of pig organs in baboons is also getting longer and longer. (As shown below)
Up to now, the genetically edited pig organs have been able to survive in the baboons for at least half a year.
At the same time, scientists are also working hard to control other possible problems in xenotransplantation. For example, in the news we mentioned at the beginning, Yang Luhan used gene-edited pigs to overcome them.
But this is only the first battle in this protracted battle to overcome the problem of organ transplantation, and there are long research and clinical trials waiting for scientists.
Although pigs have lighter ethical issues than chimpanzees and are not about protecting animals, with the development of technology, our future will be very wonderful:
George Orwell’s sentence at the end of "Animal Farm" is probably in one sentence:
However, we may first consider a question: how will people who transplant pig hearts feel when they eat pork?
What do you think?