August 5, 2005

Scientists find flexible stem cells in placenta

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - Scientists looking for easier and
less-controversial alternatives to stem cells from human
embryos said on Friday they found a potential source in
placentas saved during childbirth.

They described primitive cells found in a part of the
placenta called the amnion, which they coaxed into forming a
variety of cell types and which look very similar to
sought-after embryonic stem cells.

With 4 million children born in the United States each
year, placentas could provide a ready source of the cells, the
team at the University of Pittsburgh said.

It is not yet certain that the cells they found are true
stem cells, said Stephen Strom, who worked on the study. But
they carry two important genes, called Oct 4 and nanog, which
so far have only been seen on embryonic stem cells.

"We were just blown away when we found those two genes
expressed in those cells," Strom said in a telephone interview.

"The presence of these two genes suggests these cells are
pluripotent, which means they should be able to form any cell
type in the body."

Stem cells are the body's master cells. So-called adult
stem cells are found in the tissue and blood are a source for
renewing cells.

Embryonic stem cells are found in days-old embryos. While
powerful, their use is controversial because some people,
President Bush among them, believe destroying an embryo is
immoral and unethical.

Supporters of embryonic stem-cell research say it may
provide an important path to a new field called regenerative
medicine, in which diseases ranging from juvenile diabetes to
paralysis could be cured using transplants of carefully
cultivated stem cells.

There are moves in Congress to expand funding of embryonic
stem cell research, in case it proves to be the best way
forward, but also counter-measures to further restrict it.


Mindful of the controversy, Strom's team looked for other
sources of stem cells.

"We looked and we found them. The politics is important,"
Strom said.

Writing in the journal Stem Cells, Strom and colleagues
said they looked in a part of the placenta called the amnion --
the outer membrane of the amniotic sac.

The placenta is the interface between mother and fetus
during gestation, and is produced by the embryo. The embryo and
later fetus floats inside the sac of amniotic fluid.

Other teams of researchers, notably Dr. Anthony Atala of
Wake Forest University in North Carolina, have found stem cells
resembling embryonic cells in amniotic fluid, but research is
still early and it is not known how useful those would be.

Strom says his cells are different are different from the
ones the Wake Forest team found, and they may not be true stem
cells because they did not form tumors in his experiments, as a
true stem cell would.

Strom said the cells he worked with also do not appear to
be immortal, meaning they die out after a while in the lab,
unlike true stem cells.

Strom's team tested the cells in lab dishes, incubating
them in various compounds, and got them to form into what
looked like heart cells, nerve cells, liver cells and
pancreatic cells.

Strom's lab works specifically on liver transplants and he
hopes to develop the cells to use them instead of donated
liver. Pancreatic cells would be important because they could
be used to treat diabetes.

The university has licensed the technology to a company
called Stemnion, LLC, and the researchers are shareholders and
will receive license fees as part of the agreement.