Politics Republican Wishful Thinking on Science
posted by June 26 at 13:33 PMon
I came across this choice quote while reading up on the presidential veto of the embryonic stem cell funding bill:
“Given the tremendous results that have come from adult and umbilical cord stem cell therapy in the areas of oncology and orthopedics — and, more recently, in cardiology and neurology — I am further encouraged by the possibilities these non-controversial, adult stem cells have to offer,” said Sen. George Voinovich, R-Ohio.
What the scientific literature has to say on the potential of adult stem cells to replace embryonic stem cells:
The late 1990s and first few years of this decade were marked by dramatic reports of transdifferentiation in multiple organ systems. Examples included marrow -> skeletal muscle, marrow/blood -> endothelium, neural stem cells -> blood, skeletal muscle -> blood, marrow -> lung, marrow -> brain, marrow -> liver, and marrow -> heart. Indeed, it seemed for a while that the rules of development did not apply to adult stem cells and that simply placing these cells into new environments was sufficient to induce them to acquire the phenotype of their surrounding tissue.
After a few years, however, several of these conclusions were shown to result not from transdifferentiation but from novel processes not known to occur at the time of the initial report. For example, formation of blood from skeletal muscle turned out to result from “ectopic” hematopoietic stem cells that unexpectedly resided in skeletal muscle, rather than conversion of muscle-specific stem cells into blood. Formation of liver from marrow resulted from the fusion of blood cells with hepatocytes, and subsequent reprogramming of the leukocyte nucleus to a hepatic phenotype. Other observations were not reproducible when subsequently attempted or are suspected to result from experimental artifact.
In other words, the “tremendous results” Senator Voinovich cites have largely been debunked.
I don’t work with embryonic stem cells for pleasure. They remain the only reliable source for many crucial replacement cell types. Like beating human heart cells:
Most embryonic stem cell research has nothing to do with destroying embryos to create new lines. Rather, we spend most of our hours getting the embryonic stem cells to do useful things, like replacing the billion or so beating cells lost in a heart attack.
So, thank you Senator Voinovich for your thoughtful evaluation of the scientific literature. Now let me get back to work.