February 25, 2024

UK scientists to push for 28-day limit on cultivation of embryos

Fears of a slippery slope are unfounded, say researchers

British scientists want to extend the amount of time that they can cultivate human embryos in Petri dishes from 14 to 28 days. This is a highly controversial move, but scientists believe that it will result in great medical advances.

The 14-day limit has stood for 25 years, since the early days of IVF in the UK. After Baronness Mary Warnock issued an influential report on IVF legislation in 1984, the figure was enshrined in legislation in 1990. It was always an arbitrary number, but no one questioned it, mostly because it proved so difficult to keep the embryos alive more than a few days anyway. However, this year, Cambridge University scientist Magdalena Zernicka-Goetz cultivated human embryos for 13 days, opening up the possibility of extending the limit even further.

“Extending the rule would have benefits for our understanding of our own development, in explaining why it goes wrong and in finding ways to put those errors right,” Zernicka-Goetz told The Guardian. “However, I don’t think that we should make any change without there being a consensus among the public, ethicists and scientists. We need to set limits within which most of us are comfortable.”

Other scientists are also touting the great benefits of such research. “I think if we could extend the limit for embryo research to around 28 days, the benefits for medical research would be enormous,” says IVF expert Simon Fishel. “It would give us 20 years of research that would transform our understanding of ourselves. There is only so much we can learn from animal experiments, from other species, after all. Certain tumours, developmental abnormalities, miscarriage: there is a whole raft of issues in medical science that we could start to understand.”

Opponents of the move are crying “slippery slope” and so, surprisingly, is Baroness Warnock. She believes that if the limit is shifted, opponents of embryo research will assert that their fears have been vindicated.

As indeed they are. Professor David Jones, director of the Anscombe Bioethics Centre in Oxford told The Observer:

“In the original act, a lot of things were prohibited – the creation of hybrid embryos, the cloning of embryos and the genetic modification of embryos. These have all been swept away, so I wouldn’t be surprised if they did shift the 14-day limit. In any case the 14-day limit is not philosophically defensible. I don’t think there is a difference between a 10-day-old embryo and a 20-day embryo in terms of its moral status.”

However, leading stem cell scientist Robin Lovell-Badge, of the Francis Crick Institute in London, insists that misgivings about a slippery slope are unfounded. The 28-day mark will be “an inflexible barrier” which “would not be changed in future”.  

In the United States, scientists and ethicists are also pushing for an extension. At a conference at Harvard University in November, most of them wanted an even more permissive regime than envisaged in the UK. “My view is the 14-day rule should be looked at as a public-policy tool and not as a strict moral distinction between right and wrong,” said Insoo Hyun, associate professor of bioethics and philosophy at Case Western Reserve University. “Is it time to get rid of such lines in the sand and rely solely on clear ethical principles?”

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