Three different research groups have show that normal mouse fibroblast cells can be reprogrammed to resemble embryonic stem cells. The significance of this accomplishment has been likened to the cloning of Dolly-the first mammal cloned.
Embryonic stem cells are important as therapeutic agents due to their ability to become any type of cell in the body. According to this Nature news article, until now the only way to obtain embryonic stem cells was to destroy an embryo which raised ethical concerns. Furthermore, to get a genetic match for a patient would be extremely difficult.
The new technique uses mouse fibroblasts, a common cell type that can easily be harvested from skin, instead of eggs.
Four genes, which code for four specific proteins known as transcription factors, are transferred into the cells using retroviruses. The proteins trigger the expression of other genes that lead the cells to become pluripotent, meaning that they could potentially become any of the body's cells.
Shinya Yamanaka, a pioneer of the technique calls them induced pluripotent stem cells (iPS cells).
The technique, while promising, is not perfect. The retroviruses used to make iPS cells may themselves cause mutations and cancer. Further research must be done before the technology can be considered for human therapeutic use.
If researchers succeed, it will make it relatively easy to produce cells that seem indistinguishable from embryonic stem cells, and that are genetically matched to individual patients. There are limits to how useful and safe these would be for therapeutic use in the near term, but they should quickly prove a boon in the lab.
Not surprisingly this news has been widely reported and discussed. Other fellow Science Bloggers covering the story are:
You point out that
The retroviruses used to make iPS cells may themselves cause mutations and cancer.
This is true: retroviruses can be oncogenic. The thing that worries me more is that the gene products introduced by these retroviruses also have the potential to cause cancerous growth.
Overall, I think this research is very promising. My main beef is the way that this finding fits into the media machine that pits adult stem cell work against embryonic stem cell research, and then how the public interaction with science leads to bad policy decisions. If you are interested, check out what I have to say about this.
If researchers succeed,
That's a mighty big if. Look at the long history of woe involving retroviruses and even just adenovirus in terms of making gene therapy work--not to mention Jesse Gelsinger's death.
Good summary here: http://www.fda.gov/fdac/features/2000/500_gene.html
Thanks for sharing the link Christine.
You're right, "that's a mighty big if."
The truth is we just don't know how well gene therapy will work in any particular disease situation.
There have been a number of interesting stories about stem cells in both science and political news recently. If you have the time and interest to catch up on some, I've written my take on some of them at my blog.
Have a good weekend!