Friday, November 23, 2007

Cutting through the stem cell hype

Unless you have been living under a rock for the last week or so, it is impossible that you missed the media blitz regarding a new, "stem cell breakthrough" in which adult cells were turned into what appear to be embryonic stem cells (ESC). It is important to understand that, while this is great scientific achievement, it has no potential for therapeutic use within the foreseeable future. That great potential still only resides with what we know today as true ESC.

As usual the media blows this sort of thing completely out of proportion in order to grab a headline. We have heard the Bush administration cheering this new development as confirmation of their policy restricting use of ESC for research. Just another example of their manipulation of science for political purposes.

Allow me to put this in perspective. This advance was achieved by inserting four genes into the genome of a skin cell by use of a retrovirus vector. Therein lies the problem. As long as viral vectors are the only way we have to insert these genes, these cells can never be used therapeutically. Why, because a virus is a very inefficient, shotgun approach for inserting genetic material. It is as likely to place the genes on chromosome 1 as on chromosome 23. As likely to place the gene in a non-coding area of the genome as it is to place it right in the middle of some other very important gene, thereby causing some other problem. Which is exactly why they are reporting about a 20% rate of cancer using these cells. That will always be a problem using a viral vector.

Someday we will surely have a restriction enzyme that will go in and clip the DNA in just the right spot and insert these genes. Or better yet, a way to chemically awaken the original genes that have been silenced in adult cells. My guess is that we are 5-10 years from either possibility. Many of those needing stem cell therapy do not have 10 years, or even 5 years, to wait. And, why should they have to wait when ESC are available now which are being discarded as medical waste?

The thing I really want to emphasize is that, while turning adult stem cells into ESC is a significant achievement, for now it is more a distraction than anything else. It gives those in the Bush administration and their supporters on the religious right ammunition to delay ESC cures for many human problems such as Parkinson's, diabetes, Alzheimer's, spinal cord injury, etc.

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