Researchers plan to conduct a study to create human pancreases in rats and mice by using human induced pluripotent stem (iPS) cells, the first such attempt under new government guidelines that allow such research.

If confirmed that human pancreases can be produced normally, human organs for transplants, which are currently in short supply, could be created in the bodies of large animals, such as pigs, in the future.

The study, which could start as early as this year, was announced at a symposium in Tokyo on June 8.

The researchers, including Hiromitsu Nakauchi, a specially appointed professor at the Institute of Medical Science of the University of Tokyo, have already applied to the university’s ethics committee for permission to conduct the study.

“Human organs will not be created immediately," Nakauchi said. "But if this method is realized, it will be able to save the lives of many people. We want to proceed cautiously with our study."

If the application is approved by the ethics committee, the researchers will then apply to the government. It will mark the first time that an attempt to create human organs in animal bodies will be conducted in Japan.

The government guidelines, which were revised in March, previously banned such studies.

In the study, researchers will create fertilized eggs of rats and mice that do not have the ability to make pancreases by manipulating genes. They will then place human iPS cells into those fertilized eggs, creating “animal-human chimeric embryo.”

After that, they will transplant the embryos into wombs of female rats or mice. Pancreases resulting from human iPS cells will grow in the babies' bodies.

In the study, the researchers will not proceed to the stage in which babies are born. They will remove the embryos at the halfway point and confirm whether the pancreases have been created normally and whether human cells have spread to other areas.

Researchers at Meiji University who have been studying jointly with Nakauchi plan to implement a similar study using pigs.

As for studies on placing human cells into animals’ fertilized eggs, the government’s guidelines had approved them only when conducted outside animals’ bodies. The cultivation of embryos had also been allowed only for up to 14 days.

However, the guidelines were revised in March in response to progress being made with studies that used iPS cells. As a result, it became possible to transplant fertilized eggs into animals. The limit on the period of cultivation was also abolished.

Meanwhile, the mating of animals born through this method is banned.

These kind of studies are generating fear that creatures in which genes of humans and animals are mixed will be born.

However, a government report says that there is little possibility that creatures that have both a human and animal appearance or have high cognitive functions such as the ability to speak will be produced.