US: Scientists looking for easier and less controversial alternatives to stem cells from human embryos said yesterday they had found a potential source in placentas saved during childbirth.
A team from the University of Pittsburgh described primitive cells found in a part of the placenta called the amnion, which they coaxed into forming a variety of cell types that look very similar to sought-after embryonic stem cells.
It is not yet certain that what they found are true stem cells, said Stephen Strom, who worked on the study. But they carry two important genes, 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," Dr Strom said. "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 found in 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 say destroying an embryo is 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.
Writing in the journal Stem Cells, Dr Strom and colleagues said they looked in the amnion, the outer membrane of the amniotic sac.
Dr 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.