The Japanese government has approved research to create human embryos (fertilized eggs) using only stem cells without eggs and sperm, paving a new path for human developmental research as well as infertility treatments. At the same time, there are voices expressing concerns about social and ethical controversies.
According to the Korea Bio Association on the 18th, the Japanese government officially permitted research to create human embryos from stem cells in laboratories last month. Japanese scientists can now conduct research to create human embryos using eggs or sperm derived from induced pluripotent stem cells (iPS cells) or embryonic stem cells.
Embryonic stem cells are primitive cells that can develop into all tissues and cells of the human body from a fertilized egg. iPS cells are derived from fully developed cells that have been reverted to an embryonic stem cell state. While there is the issue of having to destroy embryos to obtain embryonic stem cells, iPS cells do not have this problem. However, they are assessed to have a lesser ability to differentiate into various cells compared to embryonic stem cells.
By permitting embryonic creation research, the Japanese government has limited the research purposes to medical studies such as infertility and genetic diseases. The cultivation period is also stipulated to be a maximum of 14 days, the same as embryos derived from women. Implanting embryos into the uterus of humans or animals is also prohibited.
In most countries, including Korea, the deadline for cultivating embryos in laboratories is set at 14 days. After this day, fertilized eggs do not split into two, thereby losing the possibility of becoming twins and beginning to grow as an independent human. From this point on, they finally become subjects of legal protection.
Although there are restrictions, Japan has been evaluated as taking the lead in the field of stem cell-based human embryonic research with this decision. A representative area of research in Japan is in vitro gametogenesis (IVG), which is the technology of converting fully matured skin or blood cells into iPS cells and then recreating eggs and sperm.
If this technology is commercialized, it will be possible to create eggs from skin cells without the painful collection of eggs from women, allowing for artificial fertilization procedures. This could reduce women's physical burden and expenses, and theoretically, same-sex parents could each have children bearing their own genetic traits. Additionally, the ability to create multiple embryos at once increases the chances of filtering out embryos with genetic diseases through pre-implantation testing.
Currently, not only Japan but also the United States, the United Kingdom, and others are competing in research in this field. In 2016, a research team from Osaka University in Japan gave birth to mice with two biological fathers. In 2023, researchers from the University of Cambridge in the UK and the California Institute of Technology in the U.S. created embryos from stem cells and cultured them up to 14 days. These embryos even developed cells that produce placental and umbilical cord structures, similar to real human embryos.
In the same year, the Weizmann Institute in Israel also created human embryos that were structurally and morphologically identical to 14-day human embryos using stem cells. These embryos grew to 0.5 mm in two weeks, fully possessing the initial structures of the brain, skin, and musculoskeletal system.
With technological advancements, there are also movements to ease regulations. The Human Fertilisation and Embryology Authority (HFEA) in the UK is reportedly discussing what tests are needed to ensure the safety of eggs and sperm cultured in laboratories before considering clinical applications.
An official from the Korea Bio Association noted, "The Japanese government may consider revising related guidelines starting with this decision," but added, "If embryos are implanted in the uterus, it could potentially lead to the birth of humans, leaving ethical controversies unresolved."
References
Nature(2023), DOI: https://doi.org/10.1038/s41586-023-06604-5
Nature(2023), DOI: https://doi.org/10.1038/s41586-023-05834-x