Saturday, August 06, 2005

US scientists find flexible stem cells in placenta


US 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.