Story at a glance
- A new study released in the journal Cell revealed scientists had created embryos that were part human and part monkey.
- The research was conducted with the aim of finding ways to one day grow organs in animals that can be used for human transplantation.
- The chimeric creation has sparked a debate about the ethics of scientists creating interspecies embryos and its larger implications.
Scientists have created embryos for the first time that are part human and part monkey, according to a new study released in the journal Cell on Thursday.
The team of scientists who collaborated on the study stated the embryos were created as research for new ways to produce organs for organ transplants. However, the research has been controversial within the science community, with some bioethicists debating the ethics behind the creation.
"My first question is: Why?” Kirstin Matthews, a fellow for science and technology at Rice University's Baker Institute, told NPR. "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."
The ethical concerns vary. One is that the research could go further and result in someone trying to create a fetus, in which the brain that develops would also be part human, part animal. Such entities are known as chimeras, stemming from Greek mythology.
"Should it be regulated as human because it has a significant proportion of human cells in it? Or should it be regulated just as an animal? Or something else?" Matthews said. "At what point are you taking something and using it for organs when it actually is starting to think and have logic?"
Another leading worry is the possibility it produces animals that then carry human sperm or eggs.
"Nobody really wants monkeys walking around with human eggs and human sperm inside them. Because if a monkey with human sperm meets a monkey with human eggs, nobody wants a human embryo inside a monkey's uterus," said Hank Greely, a Stanford University bioethicist. Greely co-wrote an article in the same issue of Cell critiquing this line of research, though he noted that the specific study in question was carried out ethically.
However, the scientists involved in the study stand behind their research and say it could be instrumental in solving one of medicine’s biggest issues.
"This is one of the major problems in medicine — organ transplantation," Juan Carlos Izpisua Belmonte, a professor in the Gene Expression Laboratory of the Salk Institute for Biological Sciences and a co-author of the study, told NPR. "The demand for that is much higher than the supply."
In the research, Belmonte and a team of scientists injected 25 human induced pluripotent stem cells into the embryos of macaque monkeys, which share close genetic similarities to humans.
On the first day, researchers detected human cells growing within 132 of the embryos. The team studied the embryos for 19 days to gain insight into how human and animal cells communicate, with the aim of one day discovering how to grow organs in animals that can be used for human transplantation.
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"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 said. "We are very, very excited."
Organ transplantation is a cause for concern in the United States, with the need consistently outpacing the availability. According to the U.S. Government Information on Organ Donation and Transplantation, 39,000 organ transplants were conducted in 2020. As of February 2021, more than 107,000 were on the waiting list for an organ transplant, and 17 people die every day while waiting for one.
The coronavirus pandemic has caused heightened concern about the availability of organs for transplantation. The damage COVID-19 does on the organs, especially the lungs, combined with that of the long-term use of a ventilator in some patients has sparked a new wave of transplant patients.
New data released by the United Network for Organ Sharing found that 59 transplants due to COVID-19-related organ disease occurred in the United States through March 31. Of these transplants, 54 were lung transplants, four were heart transplants, and one was a combination lung-heart transplant.
“I think this is just the beginning,” said Tae Song, surgical director of the lung transplant program at the University of Chicago Medical Center. “I expect this to be a completely new category of transplant patients.”
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