An influential scientific panel says researchers should be allowed to grow human embryos in a lab for more than two weeks and recommends lifting the so-called 14-day rule, according to news reports.
The 14-day rule refers to a strict cap placed on the length of time lab-grown embryos are allowed to mature, in order to avoid ethical dilemmas that would arise as the tissues became more and more human-like, STAT reported. Some countries, including Australia and the U.K., have gone so far as to write the 14-day rule into law, while other countries, like the U.S., enforce the rule through regulatory research bodies. That said, in the past, scientists struggled to keep lab-grown embryos alive for that long.
But now, cell-culturing techniques have improved, and embryos can be kept alive up to the 14-day cutoff. And on Wednesday (May 26), the International Society for Stem Cell Research (ISSCR) released new guidelines stating that scientists should be allowed to grow embryos past that two-week mark, NPR reported.
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"There's very good reasons for doing this research. And people shouldn't be scared about it if there are robust mechanisms of review and oversight," Robin Lovell-Badge, a developmental biologist at The Francis Crick Institute in London and chair of the guidelines task force, said during a news conference on May 26, according to NPR. For example, such studies could provide valuable insight into infertility, miscarriage and birth defects, he said.
Between days 14 and 28 after fertilization, embryos begin building tissues from many different cell types, and the placenta forms, STAT reported. But because many people only learn they're pregnant after the 28-day mark, this period of development is difficult to study. Lab-grown embryos could help fill that gap in knowledge.
"When you ask, 'Is this ethically bad?' Well, you also have to put the opposite: Are there ethical issues for not doing research in that period?" Lovell-Badge said, according to NPR. "In many ways, you could argue it would be unethical not to do it."
The updated ISSCR guidelines will now be reviewed by regulatory bodies around the world, whose experts can dictate if and how the new rule is adopted, NPR reported.
"This is not a green light for groups to go ahead with extending human cultures [holding embryos] beyond 14 days," Kathy Niakan, a biologist at the University of Cambridge and Francis Crick and a member of the guidelines task force, said at the news conference, according to STAT.
"It would be irresponsible — and, in many jurisdictions, it would be illegal — to do so," Niakan said. "What we're doing instead is, the guidelines are a call to proactively engage in a two-way dialogue with the public to review the 14-day limit on human embryo culture."
Not all scientists and bioethicists agree with the new ISSCR guidelines. "I think it's deeply troubling," Dr. Daniel Sulmasy, a bioethicist at Georgetown University, told NPR. "Now, any sign of respect for the human embryo is gone."
Hank Greely, a Stanford University bioethicist, told NPR he supports the new guidelines but raised concerns that no new stopping point was introduced. "If you don't have any end point, could you take embryos to 20 weeks? To 24 weeks? Is viability the only endpoint?" he asked.
The new guidelines opened the door for these kinds of questions and now serve as the grounds for useful debate in the scientific community, Alta Charo, a bioethicist at the University of Wisconsin Law School in Madison, told Nature News (opens in new tab). "We didn't debate it before — now it's time to debate," Charo said.
Originally published on Live Science.