The Japanese scientist who created pluripotent stem cells without destroying embryos, Shinya Yamanaka, of Kyoto University, has expanded upon the ethical implications of his discovery in a recent issue of New Scientist (subscription required). Here are some brief excerpts:

Fertility technology: "I can make eggs as well as sperm from my own male iPS [induced pluripotent stem] 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."

Unproven cures: "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."

Who decides 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."

The future of embryonic stem cell research: " 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." ~ New Scientist, Dec 15