Japan Approves First Human-Animal Embryo Experiments

by : Cameron Frew on : 29 Jul 2019 18:47
PA Images

While we’re far, far away from the powers of Spider-Man becoming a reality, scientists are taking bold leaps in breaking down the barriers between human and animal biology. 

Hiromitsu Nakauchi, who leads teams at the University of Tokyo and Stanford University in California, plans to grow human cells in mouse and rat embryos and then transplant those embryos into surrogate animals.


According to Nature, Nakauchi is the first stem-cell scientist to receive government funding from Japan to conduct human-animal embryo experiments. The ultimate goal is to create animals with organs that could feasibly be transplanted to people.

Hiromitsu Nakauchi for Embryo storyFlickr

As one would expect, there have been numerous ethical concerns regarding the process, such as the possibility that human cells might stray beyond the intended organ and travel to the developing animal’s brain, potentially affecting its condition.

Allaying the concerns, Nakauchi said:


We are trying to do targeted organ generation, so the cells go only to the pancreas.

Human-animal hybrids have been produced in the US, where rules are more relaxed – though the National Institutes of Health has had a moratorium on funding this type of work since 2015.

However, until March this year, Japan explicitly forbid the growth of animal embryos containing human cells beyond 14 days or the transplant of such embryos into a surrogate uterus.


Nakauchi’s plans are the first to be approved under Japan’s education and science ministry’s new guidelines, which allow the transplant of embryos into surrogate animals.

Jun Wu, who researches human–animal chimaeras at the University of Texas Southwestern Medical Center in Dallas, said this is an essential step in the exploring evolution.

Jun Wu said:

Understanding the molecular basis and developing strategies to overcome this barrier will be necessary to move the field forward.


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Cameron Frew

After graduating from Glasgow Caledonian University with an NCTJ and BJTC-accredited Multimedia Journalism degree, Cameron ventured into the world of print journalism at The National, while also working as a freelance film journalist on the side, becoming an accredited Rotten Tomatoes critic in the process. He's now left his Scottish homelands and taken up residence at UNILAD as a journalist.

Topics: News, experiment, Japan


  1. Nature

    Japan approves first human-animal embryo experiments