Stem cells have been discovered in amniotic fluid, the liquid that surrounds a fetus during pregnancy, scientists have announced.
The cells appear to rival embryonic cells in their ability to give rise to all of the major tissue types present in the human body.
Researchers at Wake Forest University in Winston-Salem, North Carolina, used the amniotic stem cells to form bone, muscle, nerve, fat, blood vessel, and liver cells.
The report by Anthony Atala and colleagues appears in yesterday's edition of the journal Nature Biotechnology.
The finding raises new hope for advances in tissue repair and organ regeneration without the ethical objections that have surrounded embryonic stem cell research.
Such objections arise because embryonic stem cells must be harvested from a fertilized human egg, which is destroyed in the process.
In contrast, amniotic stem cells can be collected during a routine medical procedure that draws fluid from the womb without harming the developing fetus. The cells can also be taken from the placenta that is expelled after delivery.
In a teleconference Friday, Atala said that while it is too soon to know their full therapeutic potential, the new stem cells have advantages over other stem cell types because they are so potent and fast growing.
"I don't think these cells are going to replace [human embryonic stem cells], but they provide another choice and are more readily available," Atala said.
Engineering Organs
Amniotic fluid is known to be rich in fetal cells of various types, and physicians have already used some of these to clone "patches" of connective or muscle tissue for repairing certain birth defects.
Atala said the cells his group isolated are unique in their ability to form a range of cell types, while also possessing characteristics of adult stem cells that generate only a single type.
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