In the latest Nature, a group of scientists at Kyoto University claims to have made true embryonic stem cells out of ordinary adult cells by switching off four genes.
In theory, embryonic stem cells can propagate themselves indefinitely and are able to become any type of cell in the body. But so far, the only way to obtain embryonic stem cells involves destroying an embryo, and to get a genetic match for a patient would mean, in effect, cloning that person — all of which raise difficult ethical questions.
[…] Last year, [Shinya] 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. Introduction of iPS cells into a developing embryo, for example, did not produce a ‘chimaera’ — a mouse carrying a mix of DNA from both the original embryo and the iPS cells throughout its body. “I was not comfortable with the term ‘pluripotent’ last year,” says Hans Schöler, a stem-cell specialist at the Max Planck Institute for Molecular Biomedicine in Münster who is not involved with any of the three articles.
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.
Assuming that the work translates to humans, which seems likely, the ethical logjam over stem cell research has been definitively broken. Drawing on my own relevant work I can say that the techniques used here are surprisingly simple and easy to translate into a therapy. If so, and plenty of hurdles always lie between proof-of-principle and usable applications, we can soon have a near-endless supply of stem cell lines that carry no more ethical taint than the thousands of ordinary cell lines in common use. Tissue-matching embryonic cells to a patient could prove as simple as a minor skin biopsy. It is not an exaggeration to say that many see the adult-to-stem cell conversion as the Grail of stem cell research.
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Breaking the political logjam could prove as important as the technical advances, although it annoys me immensely that we had one in the first place. Neither scientists, doctors nor sick patients owe any thanks to religious hypocrites and craven politicians who attack stem cell research while giving IVF clinics a pass. More than that, the stem cell issue just helps illustrate the way that the christianist lobby sees human health as a pawn in their ideological agenda. The same activists fought a near-100% effective HPV vaccine because cancer discourages unmarried sex. They primarily support a pointless ban on an abortion procedure because more young women will die of complications. Frankly, pleasing people like that is near the last of my priorities. But if the adult-stem cell conversion technique will advance medical science and also make them go away then consider me doubly pleased.
***Update***
The New York Times report is now online.