Technique removes need for eggs or embryos.With the birth of this chimaeric mouse the suggestion is that the cells used to generate it behave like embryonic stem cells. Research reported this week by three different groups shows that normal skin cells can be reprogrammed to an embryonic state in mice The race is now on to apply the surprisingly straightforward procedure to human cells. If researchers succeed, it will make it relatively easy to produce cells that seem indistinguishable from embryonic stem cells, and that are genetically matched to individual patients. There are limits to how useful and safe these would be for therapeutic use in the near term, but they should quickly prove a boon in the lab. David Cyrnoski
