Researchers say they've grown sheep embryos containing human cells—but the benefits that the work could bring are still a way off.
The news: Scientists report that they've fused human stem cells into sheep embryos, and grown the resulting "chimeras" into fetal animals over the course of 28 days.
Backstory: The same researchers already described similar experiments with human-pig chimeras. MIT Technology Review first reported that such experiments were underway back in 2016.
The big idea: It's hoped this kind of approach could be used to grow animals with human organs, as a source for transplants.
Too few cells: The new chimeras are just 0.01 percent human by cell count. That's better than the 0.001 percent of the human-pig embryos, but growing human organs will require the proportion to be nearer 1 percent.
Plus: The technique remains highly controversial. Attempts to push beyond 28 days of development will test the ethical limits of regulators.
Sam Altman invested $180 million into a company trying to delay death
Can anti-aging breakthroughs add 10 healthy years to the human life span? The CEO of OpenAI is paying to find out.
Forget designer babies. Here’s how CRISPR is really changing lives
The gene-editing tool is being tested in people, and the first treatment could be approved this year.
More than 200 people have been treated with experimental CRISPR therapies
But at a global genome-editing summit, exciting trial results were tempered by safety and ethical concerns.
Three-parent baby technique could create babies at risk of severe disease
The approach was designed to prevent mitochondrial disease, but new evidence shows it might not work as planned.
Get the latest updates from
MIT Technology Review
Discover special offers, top stories, upcoming events, and more.