Stem Cell Research: the Possibilities

Stem cells fill in for liver in mouse experiment Sun Nov 5, 4:42 PM ET

WASHINGTON (Reuters) - Stem cells grown from mouse embryos helped power a liver replacement device, Japanese and U.S. researchers reported on Sunday.

Their experiment suggests another use for the cells, controversial when taken from human embryos. They used the cells in a bioartificial liver, an implanted device that uses liver cells to replace some liver function.

Writing in the journal Nature Biotechnology, Ira Fox of the University of Nebraska Medical Center, Naoya Kobayashi of Okayama University in Japan and others said their cells saved the lives of mice that otherwise would have died of liver failure.

"Use of this device in mice with acute liver failure, which uniformly die within 4 days of inducing hepatic (liver) failure, resulted in 90 percent long-term animal survival," they wrote.

Stem cells are the body's master cells, and those taken from days-old embryos have the power to transform into any kind of cell or tissue in the body.

But the use of human embryonic stem cells is controversial, with some conservatives, including President George W. Bush, opposing their use on moral grounds.

Proponents say stem cells taken from a variety of sources could transform medicine, offering ways to understand disease and replace damaged organs and tissues.

Liver failure can be caused by viruses such as hepatitis, by drug or alcohol damage and by a range of other diseases. Often the only cure is a transplant, and more than 5,000 liver transplants are done in the United States each year.

More than 17,000 Americans are on the waiting list for a new liver.

"Treatment could be improved by bioartificial liver support, but this approach is hindered by a shortage of human hepatocytes (liver cells)," the researchers wrote.

The researchers grew mouse embryonic stem cells and coaxed them into becoming liver cells. They caused liver failure in some lab mice and implanted the bioartificial livers, seeded with the newly grown liver stem cells.

The new cells "developed characteristics nearly identical to those of primary hepatocytes (liver cells)."

The new cells filtered the blood much as the liver does, and kept the mice alive, while mice not fitted with a device died within two days, the researchers wrote.