The Japanese government has approved experiments designed to grow organs in rats and mice.
A government committee signed off on a request from University of Tokyo researchers to conduct a study to create human pancreases in rodents by using human induced pluripotent stem (iPS) cells.
“Finally, we are in a position to start serious studies in this field after 10 years of preparation,” said Hiromitsu Nakauchi, one of the scientists. “We don’t expect to create human organs immediately, but this allows us to advance our research based upon the knowhow we have gained up to this point.”
Researchers are planning to use gene manipulation to create fertilized eggs of rats and mice that don’t have the ability to make pancreases. They will then insert human iPS cells into those fertilized eggs, effectively creating animal-human embryos, which will be transplanted into the rodents’ wombs.
This way, pancreases will grow in the infant bodies due to human iPS cells.
The researchers will follow the rodents up for two years, examining their brains at various stages of development. If human cells are at any point found to exceed 30 percent of the brains of the rodent embryos, the experiment will be suspended.
The researchers also plan similar studies to create human livers and kidneys.
If this line of experimentation succeeds, it will pave the way to a future where human organs are grown in pigs or sheep, solving the chronic shortage of transplantation materials.
While other countries have experimented on creating human-animal embryos, Japan is the first to allow experiments that will see the animals with human cells come to full term.
However, some scientists have expressed concerns about the way medical advances are headed.
“If the goal of such studies is to discover a therapeutic application for humans, experiments on rats and mice are unlikely to produce a useful result because the size of the organ will not be sufficient and the result will be a far cry from humans anatomically,” said Jiro Nudeshima, a researcher who co-heads an ethics group in Japan. “It is problematic, both ethically and from a safety aspect, to place human iPS cells, which are still capable of transforming into all types of cells, into the fertilized eggs of rats and mice.”