A Japanese researcher has gotten the regulatory go-ahead to develop animal embryos that contain human cells and transplant those embryos into surrogate animals from a science ministry committee, Nature News reports. This, it adds, is the first approval of such work since Japan overturned its ban in March on creating hybrid embryos and allowing them to develop for more than 14 days or be implanted.
Hiromitsu Nakauchi, a stem cell researcher at both the University of Tokyo and Stanford University, plans to grow human cells within mouse and rat embryos, and tells Nature News that he plans to proceed cautiously, first taking the mouse embryos to 14.5 days when their organs are nearly all formed and then the rat embryos to near-term. Then, he hopes to do similar work in pigs.
His eventual plan, according to Nature News, is to grow human organs in animals that can be used for transplants. In particular, he aims to develop an animal that lacks the genetic information to develop, for instance, a pancreas, but then provide human induced pluripotent stem cells that can differentiate into that missing organ.
Nature News notes the science ministry still has to give him the final OK before he can proceed.