The federal government announced plans Thursday to lift a moratorium on funding of certain controversial experiments that use human stem cells to create animal embryos that are partly human.
The National Institutes of Health is proposing a new policy to permit scientists to get federal money to make embryos, known as chimeras, under certain carefully monitored conditions.
One issue is that scientists might inadvertently create animals that have partly human brains, endowing them with some semblance of human consciousness or human thinking abilities. Another is that they could develop into animals with human sperm and eggs and breed, producing human embryos or fetuses inside animals or hybrid creatures.
But scientists have argued that they could take steps to prevent those outcomes and that the embryos provide invaluable tools for medical research.
For example, scientists hope to use the embryos to create animal models of human diseases, which could lead to new ways to prevent and treat illnesses. Researchers also hope to produce sheep, pigs and cows with human hearts, kidneys, livers, pancreases and possibly other organs that could be used for transplants.
To address the ethical concerns, the NIH's new policy imposes several restrictions.
The policy proposes prohibiting the introduction of certain types of human cells into embryos of nonhuman primates, such as monkeys and chimps, at even earlier stages of development than what was currently prohibited.
The extra protections are being added because these animals are so closely related to humans.
But the policy would lift the moratorium on funding experiments involving other species. Because of the ethical concerns, though, at least some of the experiments would go through an extra layer of review by a new, special committee of government officials.
That committee would, for example, consider experiments designed to create animals with human brain cells or human brain tissue. Scientists might want to create them to study neurological conditions such as Alzheimer's and Parkinson's diseases. But the experiments would undergo intensive scrutiny if there's any chance there might be a "substantial contribution" or "substantial functional modification" to an animal's brain.
In addition, the NIH would even consider experiments that could create animals with human sperm and human eggs since they may be useful for studying human development and infertility. But in that case steps would have to be taken to prevent the animals from breeding.
"I am confident that these proposed changes will enable the NIH research community to move this promising area of science forward in a responsible manner," Carrie Wolinetz, the NIH's associate director for science policy, wrote in a blog post.
"At the end of the day, we want to make sure this research progresses because its very important to our understanding of disease. It's important to our mission to improve human health," she said in an interview with NPR. "But we also want to make sure there's an extra set of eyes on these projects because they do have this ethical set of concerns associated with them."
Several scientists said they are thrilled by the new policy. "It's very, very welcome news that NIH will consider funding this type of research," says Pablo Ross, a developmental biologist at the University of California, Davis, trying to grow human organs in farm animals. "We need funding to be able to answer some very important questions."
But critics denounced the decision. "Science fiction writers might have imagined worlds like this — like The Island of Dr. Moreau, Brave New World, Frankenstein," says Stuart Newman, a biologist at New York Medical College. "There have been speculations. But now they're becoming more real. And I think that we just can't say that since it's possible then let's do it."
The public has 30 days to comment on the proposed new policy. NIH could start funding projects as early as the start of 2017.
AUDIE CORNISH, HOST:
Cows with human hearts, pigs with human kidneys, sheep with partially human brains - now, this is all still in the distant future, but some scientists want to use new genetic engineering techniques and human stem cells to take the first step and create embryos that are part human, part animal. The National Institutes of Health has held off on funding this kind of work because of the ethical issues it raises. Now NIH wants to lift the moratorium and move ahead. Here's NPR health correspondent Rob Stein. He broke that news today.
ROB STEIN, BYLINE: The first thing people usually ask me is, what? Why would anyone want to make embryos that are part human, part animal? Carrie Wolinetz, a top NIH scientist says there are some really good reasons.
CARRIE WOLINETZ: It's not something that scientists are doing merely because they can. They're doing it because it's critical to really help our understanding of some of the most terrible diseases that are facing real people.
STEIN: Terrible diseases like Alzheimer's, Parkinson's, diabetes. By letting these embryos develop into animals with human cells, tissues or even entire organs, scientists can study them to find new ways to prevent and treat many illnesses. They even hope that someday they could grow fully functioning human hearts, livers, kidneys and other organs in farm animals and save thousands of people who would otherwise die every year waiting for a transplant.
But the NIH knows this can sound very "Frankenstein," so the agency imposed a moratorium on funding any of this stuff about a year ago to figure out what to do.
WOLINETZ: We wanted to make sure before the research moved forward that we were prepared to take into account any special ethical considerations.
STEIN: Like, how human can the animals be without blurring the line between humans and other species too much? Today the NIH announced a plan to lift that moratorium and greenlight these experiments. But there are a bunch of conditions.
Stay away from early embryos of monkeys, chimps and our other close relatives. Never let animals created from these embryos breed if they end up with human sperm and eggs, and make the scientists jump through extra hoops just to make sure they're not doing anything taboo, especially when it comes to making animals with brains that may be starting to become more human.
WOLINETZ: At the end of the day, we want to make sure that this research progresses because it's very important to our understanding of disease. It's important to our mission to improve human health. But we also want to make sure that there's an extra set of eyes on these projects because they do have this special ethical set of concerns associated with them.
STEIN: I talked to several scientists about the NIH's plan, and most of them are thrilled. Irving Weissman is at Stanford University.
IRVING WEISSMAN: If we can find out ways to understand and treat horrible, untreatable human diseases this way, then we should go forward cautiously.
STEIN: But there are critics who say it's just plain wrong. Stuart Newman's a developmental biologist at New York Medical College. He worries this could open up a Pandora's box - pigs with fully human brains, humans with animal brains that would be used for research or body parts. Who knows?
STUART NEWMAN: Science fiction writers might have imagined worlds like this, like "The Island of Doctor Moreau" or "Brave New World" and "Frankenstein." They've been speculations, but now they're becoming more real. And I think that we just can't say, well, if it's possible, then let's do it.
STEIN: The NIH says the new rules are designed to make sure nothing like that ever happens. The general public has 30 days to tell them what it thinks about all this, but the agency hopes to start funding experiments by early next year. Rob Stein, NPR News. Transcript provided by NPR, Copyright NPR.