After a decade of trying and a spectacular fraud in South Korea, a California company has cautiously claimed that it has cloned human embryos. In a paper in the journal Stem Cells, little-known Stemagen says that it succeeded in fusing an adult skin cell with an egg. Its scientists managed to grow five embryos to the blastocyst stage from 25 eggs, suggesting that the technique is relatively efficient. However, they did not create stem cell lines, which sceptical rivals say is the touchstone of true cloning.

Stemagen’s CEO, Dr Samuel Wood, called his team’s achievement “a critical milestone in the development of patient-specific embryonic stem cells for human therapeutic use”, including Parkinson’s and Alzheimer’s. The chief scientific office at a rival company, Advanced Cell Technology, sniffed that Stemagen's work was "underwhelming" and that its embryos "look very unhealthy, at best".

As this milestone has been so long anticipated, bioethical comment on Stemagen’s work raised two evergreen issues. If it works, where will the eggs come from? Won’t this lead to mass-producing human embryos in order to destroy them? But now, after the discovery by a Japanese team that it is possible to reprogram ordinary skin cells into pluripotent cells, there is a new question. Why bother with ethically-fraught cloning if these new cells can do the same job?

The answer is that scientists need to keep their options open, answers prominent bioethicist Arthur Caplan. “Is it a viable strategy for creating stem cells to cure diseases? A lot more research will have to be done to find out. While we wait, let’s not be frightened by scare tactics into not funding research that may be the key to curing what is currently incurable”. ~ Stemagen; MSNBC.com, Jan 17; Boston Globe, Jan 17