Researchers at the University of Tokyo's Institute of Medical Science have succeeded in generating kidneys and pancreas in mice that had been reprogrammed to grow without such organs. They injected embryonic stem cells from healthy mice into fertilized eggs.
The newborn mice were observed to have kidneys and pancreas and the researchers confirmed that they were derived from the embryonic stem cells. Vascular tracts and nerves were those of the host mice, though. According to the researchers both types of organs functioned normally.
"We have made a step forward in realizing a technique to produce human organs inside the bodies of domestic animals but we need to clear safety and ethics issues from now on," said lead researcher Prof Hiromitsu Nakauchi.
Most often in regenerative research using embryonic stem cells, risks of developing cancer in the subject have been cited. But the University of Tokyo researchers contended that the rodents used in their experiment did not develop any cancers.
As a next step, the researchers said they were planning to test the technique on monkeys and pigs to ensure its safety.