How new studies may change the stem-cell research debate

Q: What is a stem cell?

A: Stem cells are the body's master cells, the source of all cells and tissue such as brain, blood, heart, bones, muscles and skin. Because embryonic stem cells can develop into many kinds of tissue, scientists have long sought to find a way to create such cells that are genetically matched to patients as a potential path 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: What is the difference between embryonic and adult stem cells?

A: Embryonic stem cells come from days-old embryos and can produce virtually any other type of cell in the body. They are called pluripotent stem cells. Adult stem cells are harbored in blood and mature tissue in the bodies of children and adults. They are more specialized than embryonic cells and give rise to specific cell types, although they may be coaxed into a broader range of cell types under the right conditions.

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

A: Through a new method, "direct reprogramming," scientists have found a way to produce cells that appear virtually identical to stem cells that 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. Leaders of the Roman Catholic Church and some other religious and conservative political figures believe the destruction of any embryo is wrong, although some opponents of abortion rights support human embryonic stem-cell research.

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 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. Scientists hope to harness the transformational qualities of stem cells to treat a variety of diseases, including brain cells for Parkinson's disease, pancreatic cells for diabetes and nerve cells for spinal-cord injuries.

Q: How big a breakthrough is this?

A: 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.