The creation of such human/monkey chimeras "will allow us to gain better insight into whether there are evolutionarily imposed barriers to chimera generation and if there are any means by which we can overcome them," Izpisua Belmonte said in a journal news release.Īccording to Greely, "The hope has been that the human cells would work better in monkey embryos, and they could figure out why they worked better in monkey embryos and use that knowledge to make them work better in pig embryos." "The human cells survived, proliferated, and generated several … cell lineages" inside the monkey embryos, said senior researcher Juan Carlos Izpisua Belmonte, a professor with the Salk Institute for Biological Studies' Gene Expression Laboratory in La Jolla, Calif. Importantly, the percentage of human cells in the embryos remained high throughout the time they continued to grow, researchers said-meaning that the human cells were integrating into the host monkey species. Survival soon began to decline and by day 19 only three chimeras were still alive. Six days after 132 monkey embryos were created in the lab, each was injected with 25 human stem cells.Īfter 10 days, 103 of the chimeric embryos were still developing. So the researchers set out to create a chimera in a species more closely related to humans-the monkey species macaque. In 2017, members of this research team reported that they had incorporated human cells into early-stage pig tissue, but the contribution of human cells was fairly low. "That means when you're trying to test out a drug or you're trying to understand how a disease arises or develops, we don't have very good models to do that right now."įor example, such a human/animal chimera could help us better understand why the Zika virus causes birth defects in the children of infected pregnant women, Farahany said. "The kind of animal models we have right now aren't sufficient to model most of the diseases that humans suffer from-particularly brain diseases that humans suffer from, but really any disease," Farahany said. Human/animal chimeras also could help fill in blanks in our understanding of early human development following conception, and improve the study of how viruses, bacteria, drugs and devices work in humans, Farahany and Greely said. Successful human/monkey chimeras could provide clues that would allow scientists to make the leap to pigs or cattle. on a transplant list, waiting for a transplant."Īttempts to create human/pig chimeras have been only partially successful because 90 million years of evolutionary history separate the two species, researchers said. Tens of thousands of people die every year in the U.S. "They want to do that to make more human organs for transplants. "The long-term goal of this research team is to grow human organs in pigs-kidneys, livers, hearts, etc.," Greely said. "People imagine where that kind of research could go, if we're able to overcome a lot of scientific hurdles between here and here, and I think that's why people start to become uncomfortable."īut this study also paves the way for potentially lifesaving medical advances, said editorial co-author Henry Greely, director of the Stanford Center for Law and the Biosciences in California. "People still recognize there's a divide between humans and non-human primates, and when you start to introduce human cells into a non-human primate like a monkey, people start to think, what is it that you're creating?" Farahany said. Thoughts of "Planet of the Apes" or the flying monkeys in the "Wizard of Oz" spring easily to mind.
She is also co-author of an editorial accompanying the April 15 report in the journal Cell. This sort of research raises ethical concerns that can make a person queasy, said Nita Farahany, founding director of the Duke Initiative for Science & Society in Durham, N.C. The human/monkey chimeras-organisms that contain cells from two or more species-survived for up to 20 days in petri dishes, a team of Chinese and U.S.
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