Scientists believe they have come up with a major discovery, one where half-human, half-pig embryos were grown to a point where they were close to developing certain organs and body parts. This, researchers say, could pave the way for more advanced solutions for patients in need of an organ transplant.
In a study published Thursday in the journal Cell, the Salk Institute researchers discussed the technique they had used to create the unusual half-human, half-pig hybrid embryos — injecting pig embryos with human stem cells. With the human stem cells able to develop into different types of tissues, these were grown inside female pigs’ wombs and harvested after a wait of four weeks.
As the Los Angeles Times explains, the human stem cells “had established beachheads throughout the developing pigs.” That was because human cells started showing up within the small, yet distinct organs that were close to developing from the fetal pig tissue. And with organ generation so close, the L.A. Times observed that the half-human, half-pig embryos were close to becoming chimeras in the truest sense – half-human, half-beast creatures from mythology, but used in medical terminology to refer to animals with cells coming from other species.
Although the discovery is quite an impressive one, the researchers believe that they are still relatively far away from developing human organs to be used in transplants. The Huffington Post wrote that the researchers are working on “human-friendly” hearts, livers, and pancreases in pigs, with the animals growing them in place of their own pig organs, and the pigs getting euthanized before the human organs are taken out.
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“Species evolve independently, and many factors dictating the developmental programs might have diverged, which makes it difficult to blend cells from one species to a developing embryo from another,” study first author Dr. Jun Wu of the Salk Institute remarked in an interview with CNN. “The larger the evolutionary distance, the more difficult for them to mix.”
Still, the potential is very much there, as the half-human, half-pig embryos could serve as a means to grow new human organs, which patients often desperately need. The Los Angeles Times wrote that about 22 people per day die while waiting to receive a replacement heart, lung, kidney, or liver.
Senior author and developmental biologist Juan Carlos Izpisua Belmonte explained to the L.A. Times that scientists have previously tried to create organs for transplants, but hadn’t had much success.
“There has been some progress but by and large these cells are not the same as nature generates. “The idea we had was, ‘We scientists don’t know how to do this, but nature does it every day, starting with the embryo form. Why don’t we let nature do its thing?'”
CNN wrote that the chimera project had started with smaller animals – rats and mice – two similar and related species. The idea was to grow the organ cells of one animal within another, and the researchers worked on creating a mouse embryo sans pancreas. This was similar to an earlier experiment, where Stanford University’s Hiromitsu Nakauchi had bred “mutant” mice, also without pancreas, and had bred a rat pancreas inside the mice instead of the original organ.
While the percentage of human cells in the pig’s fetal tissue was incredibly small, Case Western Reserve University associate professor of bioethics and philosophy Insoo Hyun told CNN that these baby steps are nonetheless significant, and a solid accomplishment regarding the goal to grow human organs within animals.
“They just wanted to see if the cells would survive during gestation, and they did, and they kind of migrated here and there to various sites, except the brain, which is interesting.”
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The issue of ethics, however, may be a more interesting talking point surrounding the Salk Institute experiments. There are concerns that the project may result in animals developing some human traits, and there’s also the general controversy surrounding gene editing technology, as The Smithsonian wrote in a 2015 report.
Hyun, who was not involved in the Salk Institute study, had a simple, yet clever way to describe the ethical conundrum with developing half-human, half-pig chimeras.
“If you up the biological contribution of the human stem cells, are you also somehow turning (animals) morally into a human-like thing with human rights? It’s so difficult to know how you would actually address that.”
[Featured Image by Scott Olson/Getty Images]