For the first time, scientists have created embryos that are a mix of human and monkey cells.
The embryos, described Thursday in the journal Cell, were created in part to try to find new ways to produce organs for people who need transplants, said the international team of scientists who collaborated in the work. But the research raises a variety of concerns.
“My first question is: Why?” said Kirstin Matthews, a fellow for science and technology at Rice University’s Baker Institute. “I think the public is going to be concerned, and I am as well, that we’re just kind of pushing forward with science without having a proper conversation about what we should or should not do.”
Still, the scientists who conducted the research, and some other bioethicists defended the experiment.
“This is one of the major problems in medicine — organ transplantation,” said Juan Carlos Izpisua Belmonte, a professor in the Gene Expression Laboratory of the Salk Institute for Biological Sciences in La Jolla and a co-author of the Cell study. “The demand for that is much higher than the supply.”
“I don’t see this type of research being ethically problematic,” said Insoo Hyun, a bioethicist at Case Western Reserve University and Harvard University. “It’s aimed at lofty humanitarian goals.”
Thousands of people die every year in the United States waiting for an organ transplant, Hyun noted. So, in recent years, some researchers in the U.S. and beyond have been injecting human stem cells into sheep and pig embryos to see if they might eventually grow human organs in such animals for transplantation.
But so far, that approach hasn’t worked. So Belmonte teamed up with scientists in China and elsewhere to try something different. The researchers injected 25 cells known as induced pluripotent stem cells from humans — commonly called iPS cells — into embryos from macaque monkeys, which are much more closely genetically related to humans than are sheep and pigs.
After one day, the researchers reported, they were able to detect human cells growing in 132 of the embryos and were able study the embryos for up to 19 days. That enabled the scientists to learn more about how animal cells and human cells communicate, an important step toward eventually helping researchers find new ways to grow organs for transplantation in other animals, Belmonte said.
“This knowledge will allow us to go back now and try to re-engineer these pathways that are successful for allowing appropriate development of human cells in these other animals,” Belmonte told NPR. “We are very, very excited.”
Such mixed-species embryos are known as chimeras, named for the fire-breathing creature from Greek mythology that is part lion, part goat and part snake.
“Our goal is not to generate any new organism, any monster,” Belmonte said. “And we are not doing anything like that. We are trying to understand how cells from different organisms communicate with one another….”
The above comes from an April 15 story on NPR.