Commentary: The Stem-Cell Flap: Simmer Down
It looked like a shrewd move when organizers of the Democratic National Convention announced on July 12 that they had added Ronald Reagan Jr. to their roster of speakers. The son of the Republican President -- who died on June 5 of complications from Alzheimer's -- has long criticized President George W. Bush's policy of limiting federal funding for embryonic stem-cell research. Democratic candidate John Kerry has repeatedly vowed to restore the funding if he's elected, saying he thinks the cells could cure 100 million sick Americans, including Alzheimer's patients.
Kerry and other stem-cell advocates need to simmer down. It is true these cells -- which can grow into any tissue in the body -- have shown promise for treating some diseases. Washington must lift the funding ban if researchers are to unlock their full potential. But advocates are overstating stem cells' near-term ability to treat grave illnesses. In doing so, they not only distort the science; the hopes they raise among many people who are sick today are also sure to be dashed.
If researchers studying stem cells were freed from politics and amply funded, how would the world of medicine change? For some complex diseases -- including Alzheimer's -- there would be little impact. While such cells might indeed be used to repair some forms of brain damage, Alzheimer's doesn't just destroy isolated cells. Vast networks of intricate neural connections -- the very backbone of complex memories and mental skills -- die off in a process that still confounds scientists. Even if researchers could coax stem cells to repair all the pieces of the brain's broken circuitry, the new cells would be annihilated just like other brain cells. Untangling this problem could take decades of research. Even Reagan Jr. admits it may be a pipe dream. "Alzheimer's is a disease, ironically, that probably won't be amenable to treatment through stem-cell therapies," he conceded in an interview on MSNBC, where he works as a political commentator.
The picture is brighter beyond Alzheimer's and other little-understood ailments. By studying how these cells generate various tissues and organs, scientists may be able to identify the cascade of genetic signals that lead to normal human development. That will help them understand what's happening when a healthy body goes haywire.
In a few disease areas, embryonic stem cells offer hope for truly novel therapies, and maybe even cures. Take diabetes -- another complex disease, but one whose central switch has been well described. The most serious form of the illness occurs when the body doesn't produce enough insulin, the hormone that regulates blood sugar. Over the past few years, researchers have coaxed embryonic stem cells from mice to grow into insulin-producing cells.
Now scientists aim to turn human embryonic stem cells into tiny factories to generate endless supplies of pancreatic cells, which could then be transplanted into diabetes patients. "There's no good alternative," says Robert Goldstein, chief scientific officer at the Juvenile Diabetes Research Foundation International. Last year only about 400 donated pancreases were available in the U.S. for patients who required transplants of insulin-producing cells -- not nearly enough to serve the 1 million patients who needed such cells.
Recent research suggests embryonic stem cells may be useful for other disorders. On June 30, a group of Israeli scientists announced that they had transformed human embryonic stem cells into neurons that produce dopamine -- a vital brain chemical that's lacking in patients with Parkinson's disease. Then they transplanted the cells into rats that had Parkinson's-like symptoms, and the animals improved significantly. Other studies have achieved similar success in rodents with spinal cord injuries. Animal results, however, don't always translate into success stories in humans.
The pro-research camp is right to argue that throttling stem-cell research in the U.S. at this early stage will slow medical progress. But in their haste to dismantle the ban and advance stem-cell treatments, the advocates must not exaggerate the near-term benefits. Distorting the facts will bring no benefits to the millions of patients and families waiting for cures.
By Arlene Weintraub