Scientists have cured a blood disorder in mice using “induced stem cells”–adult skin cells taken from the animals’ tails that were reprogrammed to behave like embryonic stem cells. The findings are the first proof of principle for the potential of these kinds of cells to treat disease.

The cells, known as induced pluripotent cells, have been the source of major excitement among both researchers and the public. They can differentiate into many types of tissue and thus hold promise for cell replacement therapies, but they sidestep the major ethical concern associated with embryonic stem cells: destroying embryos.

In the new experiment, published online today in Science Express, Rudolph Jaenisch and his colleagues at the Whitehead Institute for Biomedical Research, in Cambridge, MA, generated stem cells from the tails of mice with a form of sickle-cell anemia–an inherited blood disorder marked by abnormal blood cells. The researchers then corrected the genetic defect and differentiated the cells into blood-forming stem cells. When injected into mice, the cells developed into healthy blood cells, and the animals’ symptoms began to improve.

Jaenisch and his collaborator George Daley did a similar experiment in 2002 using cloned stem cells. But the new findings show that induced cells can perform the same function, providing a potential mechanism for generating personalized stem cells for tissue-replacement therapies without the ethical and technical hurdles associated with human embryonic stem cells.

Scientists have already taken the first step toward translating the findings to humans. Last month, scientists from Wisconsin and Japan garnered major headlines when they announced that they had created induced cells from human skin cells, bringing the research one step closer to potential treatments. (See “Stem Cells without the Embryos.”) But researchers still face a major hurdle in using these cells in humans: they need to find a safe way to reprogram the cells, which are currently reprogrammed with viruses.