New class of stem cells

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WINSTON-SALEM, N.C. – A Wake Forest University scientist says he has discovered a new class of stem cells in women’s wombs that may provide an alternative to highly controversial embryonic stem cells.

The new cells, unlike embryonic cells, could be harvested without the destruction of early-stage human embryos. That means research and development of treatments using these cells would probably not be subject to the tight financial restrictions the Bush administration has imposed on scientific work involving embryonic stem cells.

Dr. Anthony Atala and collaborators at Wake Forest and Harvard universities found the cells in amniotic fluid, the liquid that surrounds embryos and fetuses in women’s wombs. The fluid is routinely extracted during pre-natal tests. The team has also isolated these cells in the placenta, the blood-rich organ that nourishes fetuses in the womb and is usually discarded after birth.

If the cells fulfill their promise – and not all scientists are certain that they will – they could one day be saved at a person’s birth for use later in life, Atala said. Or they could be banked to help cure diseases and make body parts that closely match the biological profiles of people needing treatment, expanding the supply of transplant organs.

“The cells are more readily available than most. There are 4.5 million births in this country each year,” said Atala, director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine. Atala’s discovery was unveiled in a report published Sunday in the journal Nature Biotechnology.

Atala said the cells he has identified are different from embryonic stem cells, but may play a role in embryonic growth and development. He suspects that amniotic fluid, as it courses through and around developing fetuses, picks up the cells they shed.

“The fetus is swallowing fluid and breathing it in through the nose. Not only does it travel through the respiratory tract, it gets into the (gastrointestinal) tract, the bladder and the kidney. This stuff is chock full of fetal cells,” Atala said.

Stem cells offer medical promise because they aren’t yet specialized to perform specific biological tasks. Instead, they can be transformed with the right chemical signals to tackle different jobs, as needed.

Scientists all over the world are rushing to develop treatments using multiple types of stem cells. Many envision them as potential human repair kits for everything from severed spinal cords, damaged hearts, disabled pancreases, scarred livers, diseased brains and much more.

But actual treatments are mostly far off, and depend on intensive research to develop clinical applications. In the United States, government-funded research into embryonic stems cells has been strictly limited under President Bush, who opposes destroying human embryos for scientific pursuits.

Atala, a urologist who still sees patients, makes this announcement with newly earned stature in the bio-engineering field. Last year he disclosed his success at making partially functioning bladders from patients’ own cells and successfully implanting them in children and teenagers with spina bifida, preventing a risky operation to stave off kidney damage.

Wake Forest recruited Atala from Harvard in 2004 and is pouring millions into his institute, which is envisioned as a cornerstone for a research park under development in downtown Winston-Salem.

Atala maintains that the line of stem cells he has identified differs from stem cells found previously by other researchers, who have also searched for the cells in animal and human amniotic fluid. Boston scientists have reported creating tracheas from amniotic stem cells taken from sheep, for instance. And Swiss researchers have disclosed success at building human heart valves from stem cells harvested from human amniotic fluid.

Those researchers, Atala said, were working with different types of cells obtained from the same biological source. His team’s cells, he said, have unique molecular fingerprints. More important, he said, they are highly flexible and, like embryonic stem cells, can be induced to make many types of human cells.

Atala and collaborators at Harvard have worked with the cells over seven years to transform them into muscle, bone, fat, blood vessel, nerve and liver cells. But unlike embryonic stem cells, the amniotic cells did not grow out of control and produce tumors, he said.

Atala and his research team will have some further convincing to do in the broader stem cell research community, said Brigid Hogan, a stem cell researcher and Duke University’s chair of cell biology who is familiar with Atala’s latest findings research.

The scientific case that the cells are unlike anything seen before is not yet airtight, she said. And the true promise of the cells remains to be seen.

“They haven’t shown that these are more useful than existing cell types in use all around the country. On the other hand, that doesn’t make this not promising or useful. All stem cells at the moment have advantages and disadvantages. You can’t say this is a panacea or a cure-all,” Hogan said.

Atala stressed that he expects it will take many years to understand the real potential of these cells and whether they are suitable for therapeutic use in patients. But laboratory studies to date are promising, he said.

His team at Harvard and Wake Forest grew brain cells from the stem cells, and inserted them into mice. The cultured cells grew and filled in a damaged portion of the mice brains, Atala said. Liver and bone cells produced from the stem cell supply also multiplied when inserted into mice.

“This work is still in its very early stages,” Atala said. “But this will be one more source of cells that are readily available for research and, maybe, clinical applications.”



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