Friday, March 26, 2004

 
No, adult stem cells do not let us "get around" using embryonic stem cells, nor should they.

I found this appalling passage amidst an otherwise unremarkable (in every sense) pro-biotech article by Michael Fumento in TCS.

But it's often the case with biotechnology that new advances eliminate older problems. In the last two years, three different US labs have found evidence that three different types of non-embryonic stem cells -- those taken from adults, umbilical cords, or placentas -- appear to be able to mature into any cell in the body. Even if all three labs fail, so many different non-embryonic stem cells have been found that can be converted into so many different types of mature tissue that there should be no need for "one-size-fits-all" stem cells.

To be blunt, the evidence that adult stem cells can mature into any cell of the body has turned out to be crap. A genuine mistake, but a mistake nonetheless. It was later discovered that these cells are likely fusing with host cells....which is vastly different than being able to differentiate into lots of new cell types. This is old news.

Clearly, and for transparent reasons, Mr. Fumento wants to ignore the cell fusion observation. Perhaps he thinks it's just another impotent viewpoint that can be dismissed as a matter of opinion. Listen carefully... discovery of cell fusion invalidates the conclusions of those adult stem cell studies. Yes, it does. It doesn't prove that adult stem cells can't be plastic. It doesn't even prove that the original observations about adult stem cells were definitely due to fusion. But, by providing a very plausible alternate explanation, it makes it impossible to draw any conclusions from those studies. Thus, it invalidates the original conclusion that adult stem cells are plastic. We now know as much about adult stem cell plasticity as if we had never done the studies. Net information gained about adult stem cell plasticity? Zero.

Plus, the assertion that so many different types of adult stem cells have been discovered that we don't need embryonic stem cells is also ridiculous. We have no evidence that adult stem cells exist in many organs, and little means to differentiate the ones we do know about. The exception, of course, is the lovely and talented hematopoetic stem cell, renewable source of the blood and immune system. We understand this particular stem cell from decades of work, time enough to sort out the reproducible experiments from the artifacts (or wishful thinking.)

Don't get me wrong. I fully support the study of adult stem cells. They just haven't supplanted embryonic stem cells in terms of potential, and I mean that both scientifically and figuratively.
posted by Amy 10:12 PM