A Scientist finds how to switch adult stem cells to embryonic version by using retroviruses to turn off and on nuclear DNA.

Today’s Nature has an article about how a scientist has turned a rat fibroblast into an “embryonic” type cell; this would mean that a doctor could take your own cells and turn them into an embryonic type cell to repair or regenerate tissue.

Last year, Yamanaka introduced a system that uses mouse fibroblasts, a common cell type that can easily be harvested from skin, instead of eggs4. 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. Yamanaka calls them induced pluripotent stem cells (iPS cells). “It’s easy. There’s no trick, no magic,” says Yamanaka.The results were met with amazement, along with a good dose of scepticism. Four factors seemed too simple. And although the cells had some characteristics of embryonic cells — they formed colonies, could propagate continuously and could form cancerous growths called teratomas — they lacked others…..

This week, Yamanaka presents a second generation of iPS cells1, which pass all these tests. In addition, a group led by Rudolf Jaenisch2 at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, and a collaborative effort3 between Konrad Hochedlinger of the Harvard Stem Cell Institute and Kathrin Plath of the University of California, Los Angeles, used the same four factors and got strikingly similar results.

The public confusion about embryonic stem cells is often due to a press that reports but lacks scientific background and tends to dismiss ethical concerns as “political”.

Yet most of the stem cell breakthroughs have been from adult, not embryonic stem cells: a fact that the press glides over in their advocacy articles.

Is no one suspicious of big companies who claim miracles while producing little results are the companies manipulating public opinion to support their research on embryonic stem cells?  The dirty little secret is that they can’t get enough private investment because investors, unlike politicians, actually check the details before pouring in their hard earned money.

Adult cells are easier to harvest: you can start with a large number, from fat, cord blood, bone marrow etc. Their DNA is the same as your own, so there are no problems with rejection. And since you start with a larger number, they don’t have to divide as much to work–there is a danger of malignant transformation after many divisions of cells.

Embryonic stem cells are best from “new” embryos (most of the estimated 100 000 “left over” embryos probably would not be viable). So that means paying a young girl to ovulate eggs (several thousand dollars per egg), combining it with sperm, making an embryo, and then taking a couple cells from the embryo, which kills the embryo.

But to put it into a donor, you run into a problem: the DNA doesn’t match. That’s what all the hype about cloning is about.  So you end up cloning. Yet cloning only changes the nuclear DNA, not the mitochondrial RNA, so it’s not a genuine match. That’s why Dolly was unheatlhy, and why it is do difficult to clone mammals.

(note here: Theoretically you could “clone” your own DNA into an egg that is not fertilized. Whether this would be ethical I have no idea, but this research is very basic, and may be years until it become practical).

If scientists can learn to simply reprogram the DNA in your own cells, it would be simpler, and cheaper. Right now, it works in mice, but human DNA might be more difficult.

And, like embryonic stem cells, there is a real danger that some of the cells could turn cancerous, either from mutation or from using retroviruses to reprogram the DNA.
Like all exciting research, take the hype with a grain of salt. However, the potential to reprogram one’s own cells to regrow organs might be the ultimate result.


Nancy Reyes is a  retired physician living in the Philippines. Her website is Finest Kind Clinic and Fishmarket, and she writes medical essays on HeyDocXanga Blog 

Be Sociable, Share!