Research teams at two prestigious universities announced a major feat of biological alchemy this week: They've taken ordinary human cells and turned them into cells with all the characteristics and promise of embryonic stem cells.

This entirely new way to derive what the researchers are calling induced pluripotent stem (iPS) cells uses neither eggs nor embryos. Instead, it reprograms body cells, reactivating genes that return them to the undifferentiated state characteristic of "conventional" embryonic stem cells.

If the new technique holds up, it will also reprogram the science and politics of stem-cell research.

Consider first the technical advance that so-called "direct reprogramming" represents. It starts with bits of skin - biological materials that are plentiful and readily available, instead of eggs that have to be extracted from women with invasive and risky procedures. Nor does it require embryos, whose destruction evokes strong objections from some religious conservatives.

What's more, direct reprogramming promises to deliver the benefits that cloning-based stem-cell research was thought to offer, without its major risks. It could yield disease-specific stem cells that would be valuable in screening... see more