In what would represent a government U-turn, the implantation of fertilized animal embryos containing human induced pluripotent stem cells (iPS cells) into animal uteruses is on the verge of being permitted, according to a draft government report unveiled on Jan. 29.
Currently, scientific activity of this nature is banned, but the Ministry of Education, Culture, Sports, Science and Technology is now close to easing the restriction, following the release of the draft report compiled by a ministry expert panel.
However, implantation of such embryos -- also known as human-animal chimeric embryos -- is likely to be limited to drug discovery and basic research aimed toward confirmation of their safety. Moreover, transplantation of organs into humans "will not be recognized at this point, from the standpoint of safety."
The change in stance follows a review by the expert panel concerning research guidelines for the creation of human organs inside the bodies of animals.
However, cross-fertilization of animals born in this way will remain banned, as will the creation of human embryos from animals that possess human germ cells.
The education ministry is expected to revise the guidelines concerning such research as early as this year, clearing a path toward new forms of organ transplantation into humans -- but at the same time likely triggering more safety and ethics-related debate on the issue.
The type of research that is predicted to commence if the restriction is relaxed is the creation of pancreases using pigs. Under this research, human-animal chimeric embryos are made by injecting human iPS cells into the fertilized embryos of pigs without pancreases. This, in theory, leads to the birth of piglets with human pancreases.
The method is also expected to create organs that can be transplanted into people with diabetes due an abnormal pancreas, by using the patient's own iPS cells.
The approach has sparked certain concerns such as the potential creation of animals that possess both animal and human appearances. However, the expert panel has played down these fears, stating that, "The possibility of this is extremely low."
The implantation of human-animal chimeric embryos into animal uteruses was initially recognized by the government's Council for Science and Technology Policy, as it was then called, in 2013 -- after which the education ministry has looked into revising the related guidelines.
In the U.S., such research has been successful up to the fetal stage, but no functioning organs have yet been created.