The government of Japan has approved a research plan to create human-animal chimeras, or organisms with both human and rodent cells. Specifically, the plan is to grow a human pancreas in the body of a rat or mouse, with the goal of harvesting organs that can be transplanted into human patients. Scientist Hiromitsu Nakauchi has been working on getting approval for such a plan for ten years. The previous guidelines in Japan were to allow this kind of cell-mixing in embryos, but not to implant them into surrogate animal mothers, nor to grow them past 14 days.
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The strategy that he and other scientists are exploring is to create an animal embryo that lacks a gene necessary for the production of a certain organ, such as the pancreas, and then to inject human induced pluripotent stem (iPS) cells into the animal embryo. iPS cells are those that have been reprogrammed to an embryonic-like state and can give rise to almost all cell types. As the animal develops, it uses the human iPS cells to make the organ, which it cannot make with its own cells.
In 2017, Nakauchi and his colleagues reported the injection of mouse iPS cells into the embryo of a rat that was unable to produce a pancreas. The rat formed a pancreas made entirely of mouse cells. Nakauchi and his team transplanted that pancreas back into a mouse that had been engineered to have diabetes. The rat-produced organ was able to control blood sugar levels, effectively curing the mouse of diabetes1.
There are quite a few hurdles between combining rats and mice and combining human cells with vasty different species. The ultimate goal is to be able to grow human organs in species closer to ours, such as pigs. Of course, there are ethical concerns. Read more about the planned experiments at Nature. -via Gizmodo
Source: neatorama