Part Human, Part Monkey Embryos Raise Ethical Concerns Among Scientists

For the first time in history, scientists have created an embryo that’s part human and part monkey. But why?

The news is being met with concern and hesitation across the scientific community. The work was just featured in the journal Cell, but the reaction hasn’t been what the scientists had hoped.

A New Way to Supply Transplant Organs

The international scientists behind the study say they created the embryos to try and find new ways of growing organs for people who need a transplant.

“This is one of the major problems in medicine — organ transplantation. The demand for that is much higher than the supply,” said Juan Carlos Izpisua Belmonte, co-author of the study and a professor in the Gene Expression Laboratory of the Salk Institute for Biological Sciences in La Jolla, CA.

Belmonte and his colleagues mention that thousands of people die every year waiting for transplant organs in the U.S. Considering the demand for organs, scientists have been injecting human stem cells into the embryos of pigs and sheep to see if they might grow human organs suitable for transplant, but these experiments have come up short.

That’s why Belmonte and his colleagues decided to try something different. They injected 25 cells known as induced pluripotent stem cells from humans, or iPS cells, into embryos from macaque monkeys, which are genetically closer to humans than farm animals.

After one day, the scientists said they found human cells growing in 132 of the embryos and were able study the embryos for up to 19 days. Belmonte says this helps scientists learn more about how these kinds of cells interact in the embryo, an important step in creating transplant organs in the future.

“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.”

But not everyone shares his enthusiasm.

Cue the Criticism

The scientific community quickly shared their concerns over the experiment and what it means for the future of organ harvesting.

“My first question is: Why?” Kirstin Matthews, a fellow for science and technology at Rice University’s Baker Institute, said in reaction to the news.

“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,” she added.

She’s not alone. Others have questioned the scientists’ motives for creating the embryos and how the public will respond to such news.

Specifically, some are worried that someone may try to grow a human being from scratch using these embryos. If so, the human cells would become part of the organism’s developing brain, mixing with that of an animal.

But Belmonte says the experiment is for a good cause and that he’s not trying to be the next Frankenstein. “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.”

He says the research could also help us learn more about early human development, which may help us better understand aging and various prenatal diseases.

Insoo Hyun, a bioethicist at Case Western Reserve University and Harvard University, doesn’t see a problem. “I don’t see this type of research being ethically problematic. It’s aimed at lofty humanitarian goals,” he commented.

“This work is an important step that provides very compelling evidence that someday, when we understand fully what the process is, we could make them develop into a heart or a kidney or lungs,” said Dr. Jeffrey Platt, a professor of microbiology and immunology at the University of Michigan.

Regardless of what happens next, Matthews says the experiment opens a broad set of questions. “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? And at what point are you taking something and using it for organs when it actually is starting to think and have logic?”

Another concern is that there could be an animal with human eggs or sperm.

“Nobody really wants monkeys walking around with human eggs and human sperm inside them,” said Hank Greely, a Stanford University bioethicist. “Because if a monkey with human sperm meets a monkey with human eggs, nobody wants a human embryo inside a monkey’s uterus.”

While Greely adds that the Cell study was done ethically, others may not adhere to the same principles.

“I don’t think we’re on the edge of beyond the Planet of the Apes. I think rogue scientists are few and far between. But they’re not zero,” Greely said. “So, I do think it’s an appropriate time for us to start thinking about, ‘Should we ever let these go beyond a petri dish?'”

While these questions remain unanswered, the National Institute of Health has been considering lifting a ban on this type of research. It’s awaiting new guidelines from the International Society for Stem Cell Research, which are set to come out next month.