NEW RESEARCH UNVEILED AS EMBRYONIC FUNDING DEBATED
A type of cell that floats freely in the amniotic fluid of pregnant women has been found to have many of the same traits as embryonic stem cells, including an ability to grow into brain, muscle and other tissues that could be used to treat a variety of diseases, scientists reported yesterday.
The cells, shed by the developing fetus and easily retrieved during routine prenatal testing, are easier to maintain in laboratory dishes than embryonic stem cells — the highly versatile cells that come from destroyed human embryos and are at the center of a heated congressional debate that will resume this week.
Moreover, because the cells are a genetic match to the developing fetus, tissues grown from them in the laboratory will not be rejected if they are used to treat birth defects in that newborn, researchers said. Alternatively, the cells could be frozen, providing a personalized tissue bank for use later in life.
The new cells are adding credence to an emerging consensus among experts that the popular distinction between embryonic and “adult” stem cells — those isolated from adult bone marrow and other organs — is artificial.
Increasingly, it appears there is a continuum of stem cell types, ranging from the embryonic ones that can morph into virtually any kind of tissue but are difficult to tame, up to adult ones that can turn into a limited number of tissues but are relatively easy to control.
The newly analyzed fetal stem cells, scientists said, have many of the advantages of both.
“They grow fast, as fast as embryonic stem cells, and they show great pluripotentiality,” meaning they can become many kinds of tissues, said study leader Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine in Winston-Salem, N.C. “But they remain stable for years without forming tumors,” he added, something embryonic cells are not very good at.
Atala and other scientists emphasized that they don’t believe the new cells will make embryonic stem cells irrelevant. “There’s not going to be one shoe that fits all,” said Robert Lanza, scientific director at Advanced Cell Technology in Worcester, Mass. “We’re going to have to see which ones are most useful for which clinical conditions.”
In the past, even hints that non-embryonic cells might have medical potential similar to embryonic ones have complicated the political push to expand federal funding for the field.
Last year, President Bush vetoed a bill that would have allowed federal funding of research on stem cells from embryos discarded by fertility clinics. The newly Democratic Congress has promised to send the same or a similar bill to Bush’s desk with even greater majorities early this term, with the House slated to vote on the matter this week.
The new work, described in yesterday’s online edition of the journal Nature Biotechnology, shows “amniotic fluid-derived stem cells” can be isolated as early as 10 weeks after conception from fluid extracted during tests widely done to detect birth defects.
With co-workers from Wake Forest and Children’s Hospital in Boston, Atala coaxed the cells to become brain cells and injected them into the skulls of mice with diseased brains. The new cells filled in diseased areas and made new connections with nearby healthy neurons.
When coaxed to become bone cells and seeded onto a gelatin scaffold that was then implanted in a mouse, the cells calcified and turned into dense, healthy bone. Under other conditions they became muscle, fat, blood vessel and liver cells.
Although several stem cell experts applauded the work, some questioned the novelty of the newly described cells. Similar cells have been under study for years with little fanfare, they noted. And though Atala’s careful characterization of them is better than any previously done, they said, it is not clear that his cells are truly different than ones others have in hand.
© 2007 Lexington Herald-Leader and wire service sources.
By Rick Weiss
THE WASHINGTON POST
