Stem cells 'fill in for liver'
2006-11-06 13:19
Washington - Stem cells grown from mouse
embryos helped power a liver replacement device, Japanese and
US researchers reported on Sunday.
Their experiment suggests another use for the cells,
controversial when taken from human embryos. They used the
cells in a bio-artificial 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 Centre, 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 four days of inducing hepatic (liver)
failure, resulted in 90% 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 bio-artificial 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 bio-artificial 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.