(STAT News) – A team of scientists from the U.S., China, and Spain reported Thursday they have created the first embryos that were part human and part monkey and kept them alive for up to 20 days in laboratory dishes.
The ethically controversial creation of chimeras — containing cells from multiple species — is part of a drive to make experimental models to help scientists better understand early development, devise new treatments for human disease, and possibly find methods to grow organs for transplant inside other animals, such as pigs or sheep. Such chimeras can be used in experiments that can’t be done with human embryos, for example, but combining human cells with those of primates ushers in new and urgent ethical concerns.
To be clear, the work, published in the journal Cell, is in very early stages. The team did not create living, breathing part-human animals. They created very early embryos and never implanted them into the uterus of any animal. Concerns about human-animal chimeras center on what Stanford bioethicist and legal scholar Hank Greely calls “brains, balls, and beauty” — worries that an animal could look at all human, be born with a human brain, or be able to reproduce.
This experiment carried none of those risks, but makes it clear that the time to start discussing the ethics of human-animal chimeras is now. “It’s a first-in-kind experiment,” Nita Farahany, a professor of law and philosophy at the Duke University School of Law who co-authored a perspective piece on the ethics of the research, told STAT. “Whenever you cross a major technological or biological hurdle like this one, it’s a good moment to stop and reflect.”
The report provides the scientific details of work that began several years ago in Spain and China and made waves after it was leaked to the El País newspaper in 2019. (The Covid-19 pandemic delayed the completion and publication of the work, the researchers said.)
In the experiment, researchers injected 25 of a specific kind of human pluripotent stem cell (called “pinnacle stem cells” because they can turn into any kind of cell, including extraembryonic cells such as placenta) into each of 132 6-day-old macaque monkey embryos. The researchers stained the human cells with an exceptionally bright red fluorescent protein called tdTomato so they would be detectable within the monkey embryo as it developed. Read Full Article at STAT News >