This method of stem cell harvesting should make the ethical groups happy.
U.S. scientists say they have isolated a new type of stem cell from amniotic fluid surrounding the fetus and from the placenta, a discovery they believe could someday provide a ready means of repairing or replacing diseased organs in patients.
The researchers have already used these “amniotic fluid-derived stem (AFS) cells,” as they’ve been dubbed, to grow human bone inside laboratory mice, nerve cells that show function and liver cells that secrete urea, a substance converted by the organ from toxic ammonia.
“It has been known for decades that both the placenta and amniotic fluid contain multiple progenitor cell types from the developing embryo, including fat, bone, and muscle,” said Dr. Anthony Atala, head of the Institute for Regenerative Medicine at the Wake Forest University School of Medicine.
“We asked the question: ‘Is there a possibility that within this cell population we can capture true stem cells?’ The answer is yes.”
Atala’s team isolated the stem cells from amniotic fluid and placental tissue left over from routine prenatal tests used to detect fetal abnormalities – both amniocentesis and chorionic villus sampling, or CVS (the latter involves taking a tiny snip of the placenta for analysis).
They found that about one per cent of all the cells were indeed stem cells, but of a kind not previously identified.
The AFS cells have characteristics of both human embryonic stem cells and adult stem cells. (Stem cells are those cells which give rise to all the different cell types in the body, from those that make up heart muscle to organs like the pancreas to neurons in the brain.)
“The cell type is totally different, which makes sense because it doesn’t come from the embryo and it doesn’t come from the adult – it’s really coming from a fetus,” Atala said in an interview from Winston-Salem, N.C.
The AFS cells grow like human embryonic stem cells, doubling in number every 36 hours in laboratory dishes, but do not form tumours when implanted in lab animals, as embryonic cells can do.
What’s more, specialized cells generated from AFS included all three classes of cells found in the developing embryo – called ectoderm, mesoderm and endoderm. Their high degree of flexibility suggests AFS cells are similar to embryonic stem cells, which are thought to be able to generate every type of cell in the body.
So far, Atala’s group has been able to prod the AFS cells into forming muscle, fat, bone, blood vessel, nerve and liver cells in the laboratory.
“It’s still in its early stages, but long-term our goal would be to develop these cells to provide therapy for patients,” said Atala, who has spent seven years working on the project.
If they do prove to have the hoped-for therapeutic value, he suggests stem cells from amniotic fluid and placental tissue – in other words, afterbirth – could be frozen and banked for future use, ideally for donors’ offspring, or even across most of the population.