Japan's science ministry is set to give researchers the green light to implant fertilized eggs containing both human and animal cells into the uteruses of animals. The goal is to grow human organs for transplantation.
Reversing a previous ban, a panel of experts on Monday basically approved a draft report opening the door to studies of human-animal chimeric embryos.
Such embryos are created by injecting human cells into fertilized animal eggs.
Researchers in other countries, including the United States, have been trying to grow human pancreases and other organs in pigs to use for transplantation.
But Japan bans the implantation of such embryos into animal uteruses.
Although the draft report allows chimeric embryos to be implanted, it forbids studies into growing human brain tissue inside animals.
Panel members cite the need to study overseas cases to see whether there is any risk of creating beings that are neither human nor animal.
The draft bans inseminating the reproductive cells of chimeras to produce offspring because such cells could contain human DNA.
The ministry plans to solicit public opinions before finalizing revisions to current guidelines.
The panel's chief, Shinichi Kosaka , says implanting the chimeric embryos has been approved because of the scientific significance.
He says the panel will keep a close eye on subsequent research to prevent the creation of human-animal hybrids.