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October 27, 2023

Questions Raised About Research on Stem Cell-based Human Embryo Models

By Kyoko Akatsuka
(Researcher, Uehiro Research Division for iPS Cell Ethics)
By Kyoko Akatsuka
(Researcher, Uehiro Research Division
for iPS Cell Ethics)

In recent years, rapid research advances have been made with in vitro embryo models that mimic a fertilized egg (embryo) from animal and human embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC). Embryo models are broadly classified into non-integrated models that partially reproduce embryonic development and integrated models that reproduce the development of an entire embryo. Scientists are actively using these models to gain fundamental knowledge about various phenomena occurring in early development that have been difficult to observe otherwise. Such findings may lead to a greater understanding of the causes of infertility, early miscarriages, and genetic diseases, as well as help to identify their treatments. Since Japanese research guidelines prohibit in vitro culture of human embryos beyond 14 days after fertilization (known as the "14-day rule"), there are high expectations that research in this area can move forward while avoiding breaking such guidelines by using alternative stem cell-based embryo models.

However, beyond these scientific developments, new ethical challenges also await. For example, even though they are "models," if they are developing and have morphology and function like "real" human embryos, it may be necessary to regulate research using embryo models. Indeed, the International Society for Stem Cell Research (ISSCR) guidelines state that integrated embryo models should only be cultured for the shortest period necessary to achieve the research purpose, should not be transplanted into the womb of humans or animals, and the research must be conducted under appropriate supervision. In the future, it will be necessary to consider new ethical issues created by these stem cell-based embryo models, as questions arise on how similarly these models function like natural embryos and interest build to culture both for extended periods, longer than those acceptable currently.

However, these ethical issues may not be familiar to everyone. Some may think that since research is conducted by scientists in a laboratory, it would be better if the rules were set by experts. However, the question at stake here is not only the pros and cons of a particular scientific study but also questions concerning our view of life, such as what kind of being we perceive the human embryo as and how we evaluate its potential to become a human being.

This is why we need to engage the general public when considering the direction of scientific research and the application of its results. Except for scientists, few people may be interested in setting up rules for research on culturing embryos and creating embryo models. However, as such research progresses, discoveries and technologies may emerge that could drastically change our outlook on life and significantly impact our lives and society. That is why, regardless of how science progresses, it is crucial to think together about the values we want to cherish and the future vision of our society.

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