Controversial proposals to extend the legal 14-day limit on lab-based embryo research have been backed by the public, according to a new study.
Despite some concerns this could lead to genetically altered humans, those surveyed largely agreed that deeper research into embryo development could unlock benefits to human fertility and health.
While it is possible to grow embryos in a lab beyond 14 days, scientists in the UK – and in many other countries around the world – are not currently allowed to.
This limit was introduced in the UK in 1990. If the UK extends the limit, its legal framework will be misaligned with the 14-day rule that still governs most countries’ embryo research. This includes the USA, Japan, China, and several European countries including the Netherlands. Some countries, including Germany and Russia, do not allow any human embryo research at all.
However, in 2021, the International Society for Stem Cell Research (ISSCR) relaxed its stance on the 14-day rule when it formally removed “culture of human embryos beyond 14 days or primitive streak formation” from its list of prohibited activity.
The limit of 14 days was originally set because the embryo’s primitive streak – when the embryo organises itself into a structure with a basic body plan – usually emerges around day 14.
Many scientists still back this 14-day limit, arguing that embryos deserve some legal protection and moral status after developing the primitive streak.
But some scientists are now proposing to extend this research window into what they call the ‘black box’ of human development. This includes weeks two to five (or days 14 to 35) in the embryo’s development – a period in early human growth that we currently know little about.
What does the UK public think about embryo research?
Funded by the Wellcome Trust as part of its Human Developmental Biology Initiative (HDBI), the study collected the responses of 70 participants. According to a press release from the Babraham Institute, who co-ordinated the project, the participants were "broadly reflective of the UK population", including people with a range of awareness of embryo research.
These participants took part in 15 hours of activities, including meetings with scientists, ethicists, policy makers, and people who had had personal experiences like IVF embryo donations.
They were asked to consider the length of the 14-day rule, as well as the role of stem cell-based embryo models.
The consultation found that most participants supported some form of extension or modification of the 14-day rule – as long as the new laws are robustly regulated and grounded in respect for the embryo.
They also expressed strong desire for the regulation of stem cell-based embryo models – embryos made using lab-grown stem cells – in medical research.
“This public dialogue is an important first step and as a scientist I am reassured by the findings but there is still a long way to go to fully understand this complex issue,” said Dr Peter Rugg-Gunn, scientific lead for the HDBI.
Advancing understanding of human development
Deeper scientific insight into embryo development could lead to improved knowledge about miscarriages, the prevention of health conditions like spina bifida (when a baby’s spine does not develop properly in the womb), and greater IVF success rates.
However, the participants expressed concern about changes to embryo research regulations leading to the genetic engineering of humans.
The scientists behind the consultation hope that the dialogue will provoke a review of the 14-day rule. In the future, the consultation responses could inform research and policy development.
“Other countries will be looking to the UK to see how we deal with the 14-day rule,” said Prof Robin Lovell-Badge, co-chair of the HDBI Oversight group and head of the Laboratory of Stem Cell Biology and Developmental Genetics at the Francis Crick Institute.
“We are not there yet with any mandate to make a change, but this does give a strong pointer.”
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