Amniotic Fluid - a New Source of Stem Cells

Stem cells can develop into many different types of tissue. This gives them the potential to help or possibly even cure many serious diseases, including Parkinson's, Alzheimer's, and heart disease, and permanent disabling injuries like those of the spinal cord. But stem cells have been controversial because they've come from the tissue of destroyed fetuses, which makes the funding of this research very hard to obtain.

Now scientists at Wake Forest University School of Medicine and Harvard University School of Medicine have found other, much less controversial sources of these cells - amniotic fluid and the placenta.

It's been known for a long time that amniotic fluid, the "water" surrounding the fetus while it's still in the uterus, contains cells. Most of these are old, shed by the fetus in the same way as cells from any human body; it's just that in the fetus these cells have nowhere to go, so they stay in the amniotic fluid. However, after seven years of searching scientists have discovered that a small number - about 1% - of these cells are actually stem cells. Unlike the other shed cells, they haven't already developed into a specific form of tissue. And scientists, working both in the laboratory and with mice, have been able to get them to grow into many different kinds of tissue, including blood vessel, bone, fat, liver, and nerve tissue.

The cells were obtained in two ways. They were taken from fluid obtained during amniocentesis, a common procedure performed during pregnancy when there's a risk of genetic problems in the fetus. They were also taken from placentas. Basically, this means that these cells can be obtained any time during pregnancy, all the way up to the period immediately after birth (the cells are taken from the placenta when it's delivered, right after the baby).

The cells are cultured for two weeks, after which they grow quickly, doubling in number every 36 hours. This means that they can produce large enough quantities of cells to meet most of the needs for tissue regeneration.

This growth is fast, but still slower than that of fetal stem cells. However, that also makes it less hazardous. Fetal stem cells, because they're so "young," can sometimes develop into tumors. Amniotic fluid stem cells are slightly more mature and don't grow into tumors.

So far these cells have developed into bone, liver, and brain tissue in mice. Scientists still need to work with the cells to get them to form kidney, pancreas, and heart tissue. And they need to determine the cells' strengths and weaknesses - what they can and can't be used for. Eventually, if the research with mice is successful, the cells will be tested in humans, but that study is still a long way off.

Still, this discovery may have helped find a way around the ethical and safety issues of using fetal stem cells. And that could pave the way for more funding, more research, and eventually help for the millions of individuals suffering from currently incurable diseases.