For the first time, a government is supporting a plan to create animal embryos with human cells and bring them to term, resulting in a type of humanimal known as a human-animal chimera.
According to Nature, a committee from Japan’s science ministry signed off on a request by researchers to grow human pancreases in either rats or mice, the first such experiment to gain approval since a government ban was reversed earlier this year.
“Finally, we are in a position to start serious studies in this field after 10 years of preparation,” lead researcher Hiromitsu Nakauchi told the Japanese newspaper Asahi Shimbun.
Researchers have previously created human-animal embryos, such as sheep and pig embryos with human cells, but those pregnancies were terminated after a few days or weeks. This experiment aims to eventually bring chimera embryos to term, resulting in the birth of real, living, breathing humanimals.
But to the disappointment of some of my coworkers (and potentially many readers), this is not a step towards catgirls, nor is it a way to cross yourself with your favorite animal. Scientists perform this kind of research with the hope of one day providing a source of transplantable human organs from animals we already have the infrastructure to slaughter, such as pigs. Human organs for transplant are otherwise scarce.
For this research, Nakauchi’s team will engineer rodent embryos that are unable to grow their own pancreases, then put human stem cells into them with the goal of having the embryos develop pancreases from human cells. They will then transplant the embryos into adult rodents, but Nakauchi told Nature they plan to proceed carefully, first growing them to near-term before pursuing a live birth some time in the future. Should too many human cells get into the embryos’ brains, they will pause the experiment, according to Asahi Shimbun.
If you have ethical concerns with this, you’re not the only one. In 2017, Carolyn Neuhaus, a medical ethicist now at The Hastings Center, told Gizmodo that scientists need to step back and have these ethical discussions as a community.