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Wednesday, October 6, 2010

The Gold Standard

Great news for stem cell research was revealed this week at Harvard Medical School: Scientists were able to make differentiated human cells become pluripotent stem cells, the kind that can become virtually any other tissue of the body.  This means that stem cells and the medical promise they hold can be efficiently derived from a wide variety of sources from the patient's own body and programmed to treat the diseases treatable by stem cells. 

Up until this week, induced pluripotent stem (iPS) cells were derived from differentiated tissues by the insertion of messenger RNA (mRNA), using viruses to inject the cells with the mRNA. As one can imagine, the use of viruses tends to contaminate the cell culture with viral material, induce the cells to have an immune response, and directly change the cellular DNA, all of which simply gunk up the whole medical application of the cells.  The Harvard scientists used a novel technique -- if you want the science, then look here. But be forewarned, you really need to be a cellular geneticist to know what they're talking about. I'm not one. It doesn't use viruses, however, and it focuses on RNA rather than DNA.

The practical benefit is that iPS cells can be obtained without the use of embryonic stem cells, which require that a living human embryo be destroyed. Some scientists, such as the director of the National Institutes of Health, cling to the fact that as far as stem cells go, embryonic stem cells are "a gold standard," meaning they are the ones that iPS cells need to measure up to, to justify continued research on human embryos.

OK, I can buy that embryonic cells are a gold standard in that sense.  However, the point of iPS cells isn't to reprogram a differentiated cell into an embryonic cell, but into a stem cell that can become any other kind of cell. Embryonic stem cells are not necessarily the gold standard of that -- because embryonic cells taken from a random embryo cannot become "your" heart or pancreas or brain cells. They can become heart or brain cells, but not any of any benefit to "you." They will always be donor cells and so induce an immune response in you, they will always act weird after a while being separated from the system in which they belong (namely an embryo developing normally into a fetus) and prone to tumor generation, and they will retain a tendency also to become what they were destined to become had the embryo they came from were permitted to live.

"Your" skin cells, however, can become stem cells and then some other needed tissue.  Now, this new technique is too new so these cells have not been used to treat diseases yet.  And, the NIH director points out that iPS cells may retain some memory of the tissue they came from.  So that is something to keep in mind as research progresses.

But something else to keep in mind: Adult stem cells are already being used to treat hundreds of diseases whereas the number of diseases successfully treated by embryonic cells is.... ZERO.  So in terms of actual medical therapies and therapeutic promise, embryonic stem cells are not the gold standard at all.

All that embryonic stem cell research appears to be good for anymore is refining our understanding of the target that iPS cells are trying to reach.  However, studying embryonic cells is not the only way to improve iPS cells, since this new technique did just that without researching embryonic stem cells at all.  And, are embryonic cells really the ones we want iPS cells to be like?  Now I'm no cellular scientists, but it seems reasonable to say that we are going to improve iPS cells by refining our ability to make them do what we want, not by making them be or act more like embryonic cells.

So. What is the need to destroy human beings to do research? Embryonic stem cells are a gold standard.  A gold standard of.... what, exactly?

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