Scientists have finally succeeded in using cloning to create human embryonic stem cells, a step toward developing replacement tissue to treat diseases but one that might also hasten the day when it will be possible to create cloned babies.

The researchers, at Oregon Health and Science University, took skin cells from a baby with a genetic disease and fused them with donated human eggs to create human embryos that were genetically identical to the 8-month-old. They then extracted stem cells from those embryos.

The embryo-creation technique is essentially the same as that used to create Dolly the sheep and the many cloned animals that have followed. In those cases, the embryos were implanted in the wombs of surrogate mothers. …

Nonetheless, the fact that the scientists were able to get cloned human embryos to survive long enough for stem cell extraction is likely to be seen as a step on the way to human reproductive cloning.