Stem cells... Get Yer Stem Cells!

In a surprising paper announced for publication in Nature Biotechnology this week, scientists at Wake Forest School of Medicine (Go Deacs!) and Harvard School of Medicine claim to have purified human embryonic stem cells from amniotic fluid. (See report in Scientific American at: Science & Technology at Scientific American.com)

Why, you may wonder (if you wonder about such things at all), is this discovery any more important or any less controversial than previously documented methods of isolating stem cells from human embryos? There are a few reasons:

1. Amniocenteses are an extremely common procedure generally used in mothers over 35 to diagnose chromosomal abnormalities such as trisomy 21 (Downs Syndrome) and other gross chromosomal abnormalities. The procedure uses a long needle to extract amniotic fluid (the fluid surrounding a fetus) and does carry some risks to the pregnancy, but is nonetheless a common procedure.

2. The stem cells which authors estimate make up 1% of all cells in amniotic fluid do not appear to be required for embryonic development; these cells have been sloughed off or otherwise discharged from the embryo and float around in the amniotic fluid. This may prove to be a critical difference for individuals who believe that the current practice of generating human stem cells, removing them from the inner cell mass of early stage embryos, is tantamount to murder. The presence of stem cells in the amniotic fluid means that they are not being removed from the actual embryo, perhaps sidestepping certain religious and ethical objections.

Are these stem cells as good as the ones that have been previously isolated? So far it appears that these stem cells have the ability to differentiate into the three main tissue types: ectoderm, mesoderm and endoderm from which all organs and tissues are made. The challenge, should this source of stem cells be proven to be as reliable as the inner cell mass, is to understand the growth factors and signals these cells require to differentiate into adult tissue types.

Perhaps such a benign source of embryonic stem cells is just what the field needs to escape the political rhetoric that currently circumscribes its research.