A group of international experts has proposed a plan to change the current limit on human embryo research from 14 days after fertilization to 28 days. This change is suggested by scientists who have been leaders in the field, including Jacob Hanna and Magdalena Zernicka-Goetz, who have developed new methods for growing embryos in the lab.
Currently, many countries have a rule that research on human embryos cannot go beyond 14 days because, before this point, embryos can still split and form identical twins, which makes it less clear that they are individuals. To work around this limit, some researchers have created “synthetic embryos,” arguing that these are not real embryos since they are made from stem cells instead of fertilized eggs. This allows them to avoid the strict regulations that apply to real embryos.
As scientific knowledge has advanced, researchers are now able to grow embryos for longer periods, making the 14-day limit seem outdated. The International Society for Stem Cell Research (ISSCR) has been advocating for an extension of this limit for several years, but new laws have yet to be established.
To gain public support, researchers emphasize that studying embryos beyond 14 days could help improve our understanding of congenital diseases, the development of the placenta, and the reasons for miscarriages, as well as enhance in vitro fertilization techniques.
The new proposed limit of 28 days is based on developmental milestones that occur during this period, such as the early stages of backbone and limb development. By 28 days, the heart starts to beat, and the embryo has a defined structure, although it has not yet developed neurons, which are necessary for consciousness and sensory perception.
The experts also mention that extending the research limit could help scientists compare synthetic embryo models with real embryos more effectively. They argue that having a clear endpoint, like the closure of the neural tube, would simplify regulations and oversight.
However, the question of when human life begins is still debated. Some believe life starts at conception, and the existing 14-day rule was a political compromise that did not resolve this issue.
To address ethical questions and build public trust, the experts suggest conducting pilot projects in specific regions, like the UK, where select research centers could explore the 28-day limit under strict ethical reviews. They also propose checkpoints to reassess the research limits if development occurs faster than expected.
With advancements in genetic editing and the potential creation of artificial gametes, researchers are pushing boundaries in embryo research. This raises concerns about the recognition of human dignity, as limits continue to shift in this rapidly evolving field.
This article has been translated and simplified by artificial intelligence from a French article “Une « feuille de route » pour des recherches sur l’embryon humain jusqu’à 28 jours”
It may therefore contain errors. The French version is the reference version..