Researchers at Harvard this week announced success at a method that could one day—maybe in several years, if all goes well—let scientists produce new stem cell lines without cloning or destroying new embryos.

Currently, there are two ways to make new embryonic stem cell lines. The cells can be extracted from embryos made during in vitro fertilization. But if you want to make stem cells that are identical to, say, those of a man with a spinal cord injury, you have to take one of his cells and use a process called somatic cell nuclear transfer, often referred to as therapeutic cloning. His DNA is injected into an egg that has had its DNA removed, and somehow, the egg makes the adult cell's DNA revert to an embryonic-like state. After the cell divides and progresses for a few days, stem cells are extracted.

But eggs are hard to get—they're hidden in the ovaries and the average woman releases only one a month—and difficult to manipulate. So the study published this week in the journal Science started with embryonic stem cells instead. Like eggs, the stem cells seemed to have the power to make adult DNA act like embryonic DNA.

The researchers used a detergent to help bring stem cells and adult skin cells close enough together that the two would fuse. Most of the study was carried out using embryonic stem cell lines that have been produced at Harvard in recent years, making research on them ineligible for federal funding. But the researchers said they also were able to fuse adult cells to cells from a stem cell line developed at the University of Wisconsin that is eligible for federal funding.

For people who object to all embryo destruction, though, it should be noted that even the handful of embryonic stem cell lines that are approved for federal funding started out as embryos.

For now, the newly created embryonic stem cells aren't ready for prime time; they still contain both the adult cell's DNA and that of the original stem cell line. But researcher Kevin Eggan says this work should help scientists understand the mysterious process by which eggs reprogram the adult DNA injected into them and give insight into the secret lives of stem cells.