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A long-sought milestone has been reached in stem cell research: transforming adult cells directly into stem cells without having to use an embryo as a vehicle.


Research teams from the University of Wisconsin in Madison and Kyoto University in Japan each achieved the feat by modifying the genetic code of adult skin cells so that they converted into what appear to be stem cells. The cells have been shown to multiply in culture and are pluripotent: they can differentiate into various types of body tissues. These stem-like cells present some important drawbacks, however: they may develop cancers, and it is not yet certain that they behave identically to stem cells.

Stem cell research that uses embryos still provides the clearest understanding of how stem cells operate as well as an essential reference for non-embryonic studies. But because embryonic stem cell research has long been subject to ethical concerns, the means to culture pluripotent cells without using embryos offers an alternative route to study human disease.