Scientists no longer describe therapeutic cloning as essential for “miracle cures” from embryonic stem cells. According to a report in the web magazine Wired, “if therapeutic cloning were vital, it would make stem cell therapies prohibitively expensive”. The real reason why scientists want to clone embryos, it seems, is for research. “The value of nuclear transfer [cloning] is not for cell therapy, it’s to do molecular research to figure out how genetic disease is manifest,” says Tom Okarma, the CEO of Geron, a prominent Californian biotech company which works with human embryonic stem cells.

Wired highlights two problems. The first is cost: personalised medical treatment based on therapeutic cloning is likely to cost up to US$200,000. The second is human rights: it would create a big demand for human eggs and open the door to a new kind of exploitation for women.

None of this has dampened researchers’ enthusiasm for cloning human embryos. Because they don’t know which avenue of research will bring success, they want to be able to investigate all avenues. “I think there is hope out there,” says Robert Lanza, of Advanced Cell Technology, a well-known Massachusetts company. “But the problem is we’ve been fooled in the past over and over with promising technologies.”