Research on embryos should be extended to 28 days. The appeal of scientists

Extending the 14-day limit for in vitro human embryo research to 28 days is key to discovering potential new treatments to reduce miscarriages and birth defects

(image: Getty Images) The time to extend the 14 to 28 day limit for research on human embryos in test tubes, an age-old issue that is the subject of heated bioethical debates. The appeal, recently published in the Journal of Medical Ethics, was launched by Sophia McCully, an ethics expert at King's College London, according to which it is necessary to extend the time limit within which research on embryos in vitro can be done to allow us to discover new potential treatments and thus avoid the risks of developmental anomalies and recurrent spontaneous abortions. Today, the expert points out, there are ethical, legislative and technological reasons to be able to modify this threshold.

Introduced 40 years ago, the 14-day rule, which marks the beginning of the development of the central nervous system has become too restrictive. "Over the past 40 years, the 14-day rule has made embryo research and therapeutic innovation possible globally," McCully comments. But now, the expert urges, it is urgent to make a political change and extend this limit without fear. "If it worked in the past, it does not mean that it should remain unchanged or it cannot be improved", comments McCully, arguing that what happens in the first 14 days significantly affects subsequent development, but without the possibility of going further and continuing the research. , the true meaning will be difficult to understand.

Given that the embryo begins to develop only after 14 days, "how can we know the beginning of our development if we cannot study it?" , asks the expert. Many experts argue that animal embryos can be used instead of human ones: macaque embryos, for example, are used for up to 20 days. However, the expert clarifies, it is not yet clear how much these biologically resemble human embryos and are, therefore, valid substitutes. Questions that will remain unanswered until a comparison can be made.

For McCully, therefore, the time has come for a change: today we have the capacity to cultivate human embryos in vitro beyond 14 days, and there are very good reasons to extend this rule to 28 days. These include, for example, greater knowledge of the development of birth defects such as congenital heart disease, which affects approximately 8 out of 1000 children, increase IVF success and reduce miscarriage rates.

The reasons are also ethical: it is legal to abort an embryo substantially "older" than 14 days and, with the appropriate consent, to research its tissues, but it remains illegal, instead, to do research on an embryo of the same duration which was not intended for implantation in the uterus. "From this analysis it emerges that there are no substantial ethical reasons for not changing the rule," concludes the expert. “Embryo research is crucial and will help us make many discoveries. Extending this very arbitrary limit is today an effort that must be reached ”.