The important thing to note is that he is crying out for society to regulate the use of this technology, he's saying that scientists can't make these decisions on their own, they just see "an opportunity".
Are there any other scenarios that could raise ethical dilemmas?
I'm not sure whether we should try to make eggs from male iPS cells and vice versa. In theory, two men could use this technology to have a baby, because you could take skin cells and use them to make an egg. [...]
Who do you think should be responsible for deciding what is ethically acceptable?
These are very difficult decisions, and I think that society should make them. It should not be scientists. They can find it difficult to think like the person on the street, and instead may see it simply as a good opportunity. We scientists can be involved in the decision-making process, but I think unless society is comfortable with the therapy it should not go ahead.
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Interview: Kyoto's stem cell pioneer by Linda Geddes in New Scientist:
Last month, Shinya Yamanaka at Kyoto University showed he could transform adult skin cells into cells akin to human embryonic stem cells. The method, which involves inserting genetic material that makes the cells' development run backwards, opens the door to stem cells specific to patients, which could be used to repair damaged organs or fight diseases such as Parkinson's and diabetes - crucially, all without the need to destroy human embryos. Linda Geddes visited Yamanaka in Kyoto and found him excited at his breakthrough but concerned over its ethical implications.
How did you feel when you realised you had made human embryonic-like cells from skin cells?
We were very surprised. We had started working on this more than a year ago, when we tried inserting four transcription factors, which regulate genes, into the skin cells. It didn't work at all. We did get some cells but they turned out to be tumour cells rather than the reprogrammed stem cells - known as induced pluripotent stem (iPS) cells - that we were hoping for. The first time we saw iPS cells was this July. What we had changed was minor stuff, like how to prepare the cells for the introduction of the foreign material, and how to culture the cells.
I felt very proud of my fellows and students who did the job: they were very patient. At the same time I felt kind of responsible for this technology we had developed because now everybody has the means to develop embryonic-like cells. And they can do it without any approval from the authorities.
Do you have concerns about this?
In theory, our work means that you can generate germ cells from iPS cells, which could be very good news for the treatment of infertility. So it is good in that sense. But I can make eggs as well as sperm from my own male iPS cells. What if somebody took those sperm and eggs from a single person and fertilised them? The result would not be a clone because of the way cells divide during sexual reproduction - the fertilised egg would not be genetically identical to the original iPS cells - but it would be something very strange and dangerous. At this time there are no guidelines or rules that would prevent this. This kind of fertility technology is still very difficult, so we don't have to worry about it too much at the moment. But now that everybody can generate these cells, it could become dangerous.
“I can make eggs as well as sperm from my own male cells”
Do you think the technology you're developing is moving too fast for regulators to keep up?
The technology has certainly moved faster than we expected. We don't feel guilty, but we do feel slightly responsible. I don't think we need the same level of regulation as for human embryonic stem cells, for example, because we are not using any embryos. But we do need to have some kind of rules or regulations in place.
Theoretically, scientists should now be able to make patient-specific iPS cells quite easily. But at the moment we have to use retroviruses to carry the foreign material into the cells, which could generate tumours. This is the same problem we have with gene therapy, so we wouldn't use this on patients yet. At this stage the iPS cells should be used only for testing out new drugs, until we find ways of making the changes without using a retrovirus.
However, it's possible that scientists in less regulated countries will offer these cells to people as a therapy for spinal cord injuries, for example. The patients may say they don't care about the risk of tumours and I am very afraid of that. In a sense I would feel responsible [if something went wrong] because we started this technology.
Are there any other scenarios that could raise ethical dilemmas?
I'm not sure whether we should try to make eggs from male iPS cells and vice versa. In theory, two men could use this technology to have a baby, because you could take skin cells and use them to make an egg.
However, compared to embryonic stem cells I really think the issues are smaller. The potential of these cells is remarkable: in theory, you can make any cell in the body. I cannot say that the technology is free from escalation, but at least it could avoid the use of human embryos, and that makes it a big step forward.
Who do you think should be responsible for deciding what is ethically acceptable?
These are very difficult decisions, and I think that society should make them. It should not be scientists. They can find it difficult to think like the person on the street, and instead may see it simply as a good opportunity. We scientists can be involved in the decision-making process, but I think unless society is comfortable with the therapy it should not go ahead.
What's the next step for you?
The next step is to try and create these cells without using retroviruses. For example, we may be able to use adenoviruses, which don't integrate their DNA into the genome of the host cell. Alternatively, small molecules might do the job.
It may take two to three years to achieve this or it may take only six months. Now that many people can work on it, there will be more competition, so progress should be faster. Ultimately this technology should allow us to know sooner whether there really is a promising future for stem cell therapy.
Did the problems with Woo Suk Hwang (the South Korean scientist who falsified data to claim he had produced embryonic stem cells through cloning) mean you had to work harder to convince others of your success?
The great thing about our work is that others, such as James Thomson of the Genome Center in Madison, Wisconsin, have reported the same thing (Science, DOI: 10.1126/science.1151526). This is good because it is not just one group claiming to have done this. We know at least three or four other groups who have now succeeded in producing human iPS cells. Ian Wilmut, the British scientist who produced Dolly the cloned sheep, has also said that he wants to work with iPS cells.
Do you agree with Wilmut that this breakthrough will avoid the need for cloning?
There is still the problem with retroviruses to overcome. If we cannot do this then there will still be a need for cloning. However, I think it will be possible.
We also need a more detailed comparison between iPS cells and embryonic stem cells in terms of what they do. If it is proved that iPS cells are as good as or better than embryonic stem cells, I think they can replace them. I do want to avoid the use of embryos if possible. Ultimately I think that patients' lives are more important than embryos, but I do appreciate that embryos can become beautiful babies as well.
Shinya Yamanaka originally studied medicine at the University of Kobe, Japan. After earning a doctorate in pharmacology and completing a residency in orthopaedic surgery, he travelled to the University of California, San Francisco, where he laid the foundations for his current research. In 1996 he returned to Japan and is currently professor at the Institute for Frontier Medical Sciences at Kyoto University. Last summer he also renewed ties with UCSF as titled researcher in stem cell biology and professor of anatomy. His latest breakthrough was published in Cell (DOI: 10.1016/j.cell.2007.11.019).
Should Einstein feel "guilty" or "responsible" for cracking the E=MC(2) code? MH.
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