Induced pluripotent stem cells change the ethical debate

My latest Mind and Matter column in the Wall Street Journal is on stem cells:

The chief medical ambition of those who study stem cells has always been that the cells would be used to repair and regenerate damaged tissue. That's still a long way off, despite rapid progress exemplified by the presentation of the Nobel Prize next week to Shinya Yamanaka of Kyoto University for a key stem-cell breakthrough. But there's another, less well known application of stem cells that is already delivering results: disease modeling.

Dr. Yamanaka used a retrovirus to insert four genes into a mouse cell to return it to a "pluripotent" state-capable of turning into almost any kind of cell. Last month a team at Johns Hopkins University and the Sloan-Kettering Institute for Cancer Research, using a version of Dr. Yamanaka's technique, successfully grew nerve cells from a patient suffering from a rare disease called Riley-Day syndrome, which is linked to early mortality, seizures and other symptoms and caused by a fault in one gene.

But the purpose was not to put these cells back into the patient. Instead the scientists tested 6,912 chemical compounds on the cells to see if they could find one that "rescued" the "expression" of the gene: that is to say, caused it to produce the protein it is supposed to produce. One of the compounds worked, inducing the gene to be actively transcribed by the cell.

In the not-very-distant future, when something is going wrong in one of your organs, one treatment may be to create some stem cells from your body in the laboratory, turn them into cells of that organ, or even rudimentary structures, and then subject them to experimental treatments to see if something cures the problem. The goal of personalized medicine, in other words, may be reached by stem-cell researchers before it's reached by geneticists.

Further breakthroughs are coming thick and fast to bring that goal closer. Just last week a team largely from Cambridge University announced that they had grown abundant stem cells from particular kinds of blood cells. Amer Rana and his colleagues isolated "late outgrowth endothelial progenitor cells" from patients' blood and then induced them to become stem cells, from which they will be able to grow blood vessels. The first use will be to test drugs on those vessels.

The advantage of these blood-derived stem cells, compared with those derived from skin cells, is that they can be generated in stable form in quantities that allow multiple drug testing. Dr. Rana's team induced stem cells from both healthy people and those with various kinds of a disorder known as pulmonary arterial hypertension. Studying the differences and testing treatments comes next.

Until Dr. Yamanaka's breakthrough of five years ago, few biologists held out much hope that the cells of an adult person could be made into stem cells, in contrast to those of an embryo. Debate still continues among biologists about whether such adult cells approach the gold standard of adaptability that embryonic stem cells show, but few would now bet against that goal being achieved one day.

It's not far-fetched to conclude that, thanks to induced pluripotent stem cells, the embryonic stem-cell debate is fading fast into history. If stem cells derived from the patient's own blood are to offer the same therapeutic benefits as embryonic stem cells, without the immunological complication of coming from another individual, then there would be no need to use cells derived from embryos.

Indeed, that was one of Dr. Yamanaka's original motivations when he set out to induce pluripotency in adult cells. Though he supported embryonic stem-cell research in principle, he once said: "I thought, we can't keep destroying embryos for our research. There must be another way."