Mothers' Wombs Could Provide Stem Cells Without Ethical Controversy
Scientists have found a new source of stem cells that does not involve destroying embryos. The cells can be harvested easily from the fluid surrounding developing babies in the womb and could help overcome ethical concerns.
It has been known for decades that the placenta and the amniotic fluid in the womb contain important cells. "We asked the question: is there a possibility that within this cell population we can capture true stem cells? The answer is yes," said Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest, who led the research.
Stem cells can grow into any type of body tissue and are used to research cures for conditions such as diabetes and brain disorders, including Alzheimer's and Parkinson's disease. It is hoped that one day they may be used to grow replacement tissue that is a perfect genetic match for patients with damaged organs.
Stem cells from embryos are highly prized because they are the most adaptable. They are hard to obtain, however, because they are normally harvested from embryos left over from fertility treatments. Anti-abortion campaigners argue this leads to destruction of human life. Adults also have stem cells, but these can turn into fewer types of body tissue.
Researchers said the newly discovered amniotic fluid-derived stem (AFS) cells represent an intermediate stage between embryonic and adult stem cells. They grew AFS cells into muscle, bone, fat, blood vessel, nerve and liver cells. "Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well," said Prof Atala. His results are published today in the journal Nature Biotechnology.
"These cells are capable of extensive self-renewal, a defining property of stem cells," he said. "They also can be used to produce a broad range of cells that may be valuable for therapy."
Aside from ethical concerns, it is difficult to extract cells from leftover embryos, which are often of poor quality. AFS cells are readily available from samples taken for amniocentesis -- which involves testing the amniotic fluid for signs of genetic disorders -- and from the placenta. Around 1% of cells in these samples have been found to be stem cells. They grow quickly without turning into tumours, a problem for other types of stem cell.
"So far we've been successful with every cell type we've attempted to produce from these stem cells," said Prof Atala. "The AFS cells can also produce mature cells that meet tests of function, which suggests their therapeutic value."
In one test researchers grew brain cells from AFS cells and implanted them into mice suffering from a degenerative brain disease. The cells successfully repopulated the damaged parts of the brain. Viable bone cells were made the same way.
Prof Atala said 100,000 samples of AFS cells could supply perfect genetic matches to treat 99% of the US population.
Jo Brodie of Diabetes UK said the results were another development offering hope of a cure for the disease.
Last week scientists warned the search for therapies for diabetes and Alzheimer's disease would be hampered if they were not allowed to source more stem cells by creating embryos that are part animal, part human. These arise from injecting human genes into eggs from cows or rabbits. Scientists are awaiting approval for the research.
FAQ: Fluid option
What is amniotic fluid?
The liquid that envelops a developing baby -- it allows movement of the foetus while protecting it from injury. It contains a small amount of nutrients and cell material.
Is extracting the fluid safe?
Amniocentesis involves inserting a needle to extract amniotic fluid, usually to test for genetic abnormalities in the baby. It is straightforward but complications can arise if pathogens are introduced by the needle or the wound does not heal properly.
How can the cells be used?
If they prove useful the stem cells could be stored in a cell bank and cloned indefinitely for research or to provide therapies such as growing tissue that is genetically matched to damaged tissue in a patient.