Questions, Answers on Stem Cells

Tuesday, Nov. 20, 2007 | 2:15 a.m.

Embryonic stem cells can develop into all kinds of tissue. Scientists have long sought to find a way to create such cells that are genetically matched to patients, because of the potential for new ways to treat disease and injury.

They've pursued this through cloning, which uses embryos. But through a new method, "direct reprogramming," scientists have found a way to produce cells that appear virtually identical to stem cells, without using embryos.

Q: How big a breakthrough is this?

A: Huge. One researcher compared it to the Wright Brothers' airplane. Ian Wilmut, who cloned Dolly the sheep, said he is dropping the cloning approach for stem cells to begin testing this new method.

Q: What's so great about this new approach?

A: It doesn't require women's unfertilized eggs to make embryos; human eggs are in short supply for research. And it doesn't involve the destruction of embryos, which is required to harvest stem cells from within them. That destruction has led some groups to oppose the cloning approach for ethical and religious reasons.

Q: Does this mean scientists will no longer need human eggs or embryos?

A: No. Scientists say research should continue on embryonic stem cells. But this new development will likely reduce the demand.

Q: How does the new method work?

A: Four genes were inserted into each skin cell. Scientists knew these particular genes turn other genes on and off, but how the combination converted skin cells into mimics of stem cells remains a mystery.

Q: Are these cells so-called "adult stem cells?"

A: No. That term refers to cells found in the body that already have the ability to morph into a variety of cell types. They don't need the four-gene treatment.

Q: Are there any drawbacks to this new approach?

A: At this early stage, the technique being used disrupts the DNA of the skin cells, which leads to a potential for cancer. For now, that makes it unacceptable as a way to create stem cells for disease treatment. But the DNA disruption is just a byproduct of the technique, and experts believe there is a way to avoid it.

Q: What does it mean for average people? Can we expect to see new treatments anytime soon?

A: Not for years. Besides overcoming the cancer obstacle, scientists still have to answer basic questions about these cells. In medicine, these cells would probably be used first for lab studies like screening potential drugs.