It definitely sounded logical to Dr. Evan Snyder, co-author of a new study in Nature Biotechnology that discovered that stem cells can be isolated from amniotic fluid - the bag of water the fetus floats in during pregnancy - and developed into bone, muscle, liver, brain, and yada yada cells more easily than previously thought. After all, if that fluid was there in the early days of embryonic development, it's quite possible that some stem cells from that critical period would have washed off into the fluid.

It doesn't necessarily mean that we have found an alternative to embryonic stem cells, as mentioned in the complete news report from the San Francisco Chronicle. Embryonic stem cells, notes the other author of the study, Dr. Anthony Atala, have the total "pluripotency" to turn into whatever cells are needed. Further studies may be needed to discover the limits of the pluripotency of amniotic fluid stem cells.

On the other hand - and this is a just-as-important other hand - amniotic stem cells have other important benefits. Embryonic stem cells have the potential to develop into cancerous tumors, precisely because they are pluripotentious. Amniotic cells, on the other hand, have a lower risk of developing into tumors precisely because of their limited pluripotency.

In addition, amniotic cells don't need to be grown on a layer of "feeder" stem cells, unlike their embryonic counterparts. Finally, they lack the immune system flags or markers on them that alerts a patient/recipient's immune system to reject them when implanted.

In the face of the high-profile political and ethical debate over embryonic stem cell research, scientists, including Drs. Snyder and Atala, still maintain that they need access to all sources of stem cells, embryonic or otherwise, in the research process. On the other hand, "scientists are opportunistic," says Snyder - "they will use whatever works". And if amniotic stem cells work? Atala estimates that a hundred thousand specimens will be needed to create a stem cell bank for 99% of the US population.

Memo to expecting parents everywhere: one day, the hospital may want to keep the water that came with your baby.