Bioethicists Concerned over Japan’s Chimera Embryo Regulations

Many researchers see the move to relax the rules as a welcome change, yet some are worried the revisions don’t take public concerns enough into consideration.

katya katarina zimmer
| 5 min read
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Japanese regulators have effectively given the green light to research involving human-animal chimera embryos, which are created by implanting human pluripotent stem cells into animals in early development. The revised guidelines, issued in early March, lift a previous requirement to terminate such embryos after 14 days.

The revisions now pave the way for Japanese scientists to study how to grow human organs in animals as an alternative to organ transplantation, and to produce better models to study human development and disease.

However, they also raise some ethical concerns, as a group of Japanese bioethicists at the Kyoto University note in a letter published today (April 4) in Cell Stem Cell. For instance, the guidelines would allow researchers to create chimeras with human cells populating animal brains—something that concerns the Japanese public. They also don’t explicitly prohibit chimera embryos made from human and nonhuman primate cells, which ...

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Meet the Author

  • katya katarina zimmer

    Katarina Zimmer

    After a year teaching an algorithm to differentiate between the echolocation calls of different bat species, Katarina decided she was simply too greedy to focus on one field. Following an internship with The Scientist in 2017, she has been happily freelancing for a number of publications, covering everything from climate change to oncology.
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