What are human animal hybrids

Human-sheep hybrids grown in the laboratory

In 2017, scientists used this method to successfully breed mouse pancreases in rats and showed that these organs could cure mice with diabetes when transplanted. Just a day later, scientists from the Salk Institute announced that they could keep pig embryos alive with human cells for 28 days.

Stem cell experts praised the pig study, but pointed out that the number of human cells in the pigs - about one per hundred thousand - was too low for successful organ transplants.

Then at the American Association for the Advancement of Science's annual meeting in Austin, Texas, University of California Davis researcher Pablo Ross and his colleagues announced that they could improve the process: they have reduced the number of human cells in sheep embryos to one increased in ten thousand.

"We think that's probably still not enough to make an organ," Ross said at a press conference. According to the Guardian, about one percent of the embryo would have to be human for an organ transplant to work. In order to prevent an immune reaction, additional measures would have to be taken to remove residues of animal viruses in the DNA of the pig or sheep. Your new work, however, shows progress on the way to functioning organs.


According to Ross, research would advance faster if better funded. Currently, the US National Institutes of Health are banning public funding of human-animal hybrid research, despite hinting in 2016 that the ban could be lifted. (So ​​far, early research was funded by private donors.)

As the work progresses, the controls on the ethical justification of the experiments will also increase. Ross and his colleagues are aware of the controversial nature of their work, but emphasize that they proceed with caution.

“At the moment, the contribution made by human cells is very small. It's not like we have a pig with a human face or a human brain, ”said Ross‘ colleague and researcher at Stanford University Hiro Nakauchi during the meeting. He stressed that the researchers are trying to limit the cells from multiplying to specific areas to make sure they don't implant themselves in the brain or reproductive organs.

For Ross, in any case, the diverse approaches in the field of organ research are cause for optimism.

"All of these approaches are controversial and none are perfect, but they give hope to the people who die every day," he said. "We have to research all possible alternatives to supply sick people with organs."

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