Stem cell research guidelines relax

For decades, international ethics standards said scientists studying human embryos in a lab shouldn’t let them grow for longer than 14 days. But the International Society for Stem Cell Research on Wednesday released new guidelines removing that limit. It doesn’t suggest a replacement.

What does that mean for research? Many countries have their own “14-day rules” or other restrictions that would have to change before scientists could actually experiment on more developed human embryos. The guidelines still forbid human cloning, transferring human embryos into animal uterus, creating human-animal chimeras, and genetic editing that could pass on to future generations. But scientists in China have already broken some of those limits. And Robin Lovell-Badge, chair of the group, said that last restriction could be up for debate in the future. Opponents of human stem cell research have noted the ethical problems with experimenting on embryonic humans and argue the methods aren’t necessary for scientific advancement.

Dig deeper: Read Julie Borg’s report in Beginnings about another international panel trying to hammer out ethical guidelines for scientific research on embryos.