What is "chimera technology" that makes human organs in pigs and sheep?

Transplant surgery that transfers body tissues and organs must wait indefinitely until a donor is not found. Technologies that might be the light to eliminate such transplantation waiting states are to create human organs inside the animal's body "Chimera technology"is.

Human-Animal Chimera | MIT Technology Review
http://www.technologyreview.com/news/545106/human-animal-chimeras-are-gestating-on-us-research-farms/

◆ Chimera of humans and animals
Some of the research centers in the United States are trying to raise a part of the human body inside the pig and sheep and ultimately make organs such as the heart and liver that can be transplanted to humans. This attempt to grow organs in the body of an animal often receives ethical criticism as an act of threatening the boundaries of species, as human cells need to be injected into animal embryos. In September 2015, the National Institutes of Health converted the policy that was set up in the early stages of research to support support for research on body tissues "human and animal chimeras" made by combining animal embryos and human cells, We announced that we will cut off the impact on society until further investigation is done. The National Institutes of Health said in a statement, "I am worried that if we eventually use human brain cells, we may be able to change the" cognitive state "of animals." I will.

Many scientists who knew the announcement of the National Institutes of Health have started activities to obtain other sources of funding. Human and animal chimeras can be made by injecting human stem cells into animal embryos. After that, human body tissues are made in the body of pregnant animals. According to a survey by MIT Technology Review, in the last 12 months it seems that 20 chimeras of "pig and human" or "sheep and human" are pregnant, but at the moment the paper on human and animal chimeras is published There is also no news that Chimera was born.

ByJoe de Sousa

Juan Carlos Izpisua Belmonte of the Soak Institute, which is conducting research on human and animal chimeras, reveals that more than 12 pigs succeeded in pregnancy with humans. Also, the University of Minnesota has released a picture of the fetus of a pig containing human cells (day 62 of pregnancy), and it was revealed that this fetus had an eyeball abnormality congenitally.

Research relies on state-of-the-art fusion technology, and these include stem cell biology andGenome editingIt seems to be a breakthrough in technology. In genome editing, scientists can easily modify the DNA of embryos such as pigs and sheep, but by themselves they can not only form certain tissues. Therefore, the purpose of research on human and animal chimeras is to grow organs that can be used for transplant surgery in the animal's body by injecting human stem cells. Daniel Garry of the University of Minnesota, who is involved in this research, says, "We can produce animals without heart, sometimes we have made skeletal muscles and bloodless pigs." Mr. Garry has succeeded in obtaining a grant of US $ 1.4 million (about 160 million yen) from the US Army against a study on human and animal chimaera that raises the human heart within pigs It is.

ByU.S. Army RDECOM

Many researchers including Mr. Garry have been pursuing research on the policy change of the National Institutes of Health, since the chimeric technology can become a new source of human organ transplantation. In November 2015, 11 chimeric technology researchers including Mr. Garry said about the policy change "abort of research support" by the National Institutes of Health "fear of progress" "negative shadow (against chimeric technology)" It is a thing that throws a statement to criticize. "

Concerned about chimeric technology
However, of course there are concerns about chimeric technology, and incorporating human cells also has the potential to create chimeras with high intelligence and parts of the human body. The US National Institutes of Health commented, "We are afraid to say" I want to go out ", a highly intelligent mouse was born."

Still, it is thought that an animal probably will not have a human-like consciousness. That is because the brains of animals are much smaller than those of humans. On top of that, researchers do not produce complete chimeras of animals and humans as a precautionary measure. Instead, it is investigating what kind of influence comes out by injecting human cells into animal embryos.

ByKurt Bauschardt

◆ The forerunner of chimera technology is Japanese researcher
Advance research on chimeric technology at Stanford UniversityYoshimitsu NakauchiAccording to Mr., so far the influence of human cells on animals' bodies seems to be relatively small, "Human cells have a range of about 0.5%, which makes us thinking pigs and two legs There will be no such thing as a sheep standing in. If, however, the scope of this influence spreads, for example to about 40%, we need to take some measures. "

Also, human and animal chimeras are already widely used in many scientific investigations, one example of which is that "humanized rats by giving a human immune system" are likely to exist. Such a chimera is born by transplanting liver and thymus ingested from an abortion or miscarried fetus into a fresh mouse.

In 2010, Mr. Nakauchi succeeded in producing rat pancreas in mice using pluripotent stem cells in Japan. Regarding this, "The purpose I worked on regenerating organs is only clinical application.If you can only regenerate organs between the same species, human organs can only be regenerated using humans, which is ethically permissible If it shows the possibility of regenerating organs among different species, it is not a dream to raise human organs, for example, in a pig's body, although ethical problems may still remain, There is much more reality than growing up in the human body at least, "Mr. NakauchiTalkis.

However, because Japan's adjustment to chimera technology was very slow, Mr. Nakauchi will go to the United States in 2013. This is because American law did not set limits on the generation of chimeras. In addition, because Stanford University studies chimera technology by Mr. Nakauchi,California Institute for Regenerative Medicine(CIRM) received 6 million dollars (about 710 million yen) subsidies. Also, since CIRM has been implementing measures to prevent political interference from Washington 10 years ago, even after the National Institutes of Health announced the chimera technology, Mr. Nakauchi's research was totally affected Is not ...

ByJun Seita

Mr. Nakauchi's research uses iPS cells that reprogram skin and blood on human stem cells injected into animal embryos. And it seems that most of the iPS cells used by the research team were created from Mr. Nakauchi's blood. For this reason Mr. Nakauchi says, "If we make iPS cells from blood obtained from volunteers and inject them into animals, special agreement will be needed, so I made from my own blood I'm using something like that. "

According to Mr. Nakauchi, when hearing chimera technology, many people imagine monsters appearing in myths, but when explaining the details of the research in detail it seems that many people will change their mindset. One of the reasons seems to be due to the fact that if the embryo injected by Mr. Nakauchi's iPS cells grows in an animal body, the chimera raised in the body will fit as a complete transplant organ. Also, it may take years to wait for the order of transplant surgery, but using chimeric technology it is possible to produce organs for transplant within a year.

In addition, Mr. Nakauchi said, "In my opinion, there is only a minimal influence of human cells, probably 3 to 5%, but if we were to have 100% influence on the brain by any chance? What if they were growing up almost like humans? These are different results from what we expect, but as no one else is going to do it can not be excluded, "he says about chimera technology.