When injected with rat stem cells as embryos, mice that were unable to produce their own pancreas grew a rat one instead, according to researchers at the University of Tokyo in Japan. The pancreas, comprised of nearly all rat cells, seemed to function perfectly—the mice showed no signs of diabetes. The technique, which the researchers hope to apply to other organs and other species, could theoretically be used to create chimeric animals capable of growing human organs seeded with a patient's own stem cells, reducing the risk of immune rejection. By injecting human blood stem cells into pig fetuses, for example, the researchers were able to make pigs that could generate human blood. If successful, the strategy could also help battle organ shortages and long waiting lists for transplants.
"The technique, called blastocyst complementation, provides us with a novel approach for organ supply," said Hiromitsu Nakauchi, director of the Center for Stem Cell Biology and Regenerative Medicine at the University of Tokyo. "We have successfully tried it between mice and rats. We are now rather confident in generating functional human organs using this approach."
It is a bit of a "long shot," however, Chris Mason, chair of regenerative medicine at University College London, told The Telegraph. "There is a long way to go before it could result in useable transplants, but it is an exciting vision."