A few months ago, Dr. Thomas Einhorn was treating a patient with a broken ankle that wouldn't heal, even with multiple surgeries. So he sought help from the man's own body. Einhorn drew bone marrow from the man's pelvic bone with a needle, condensed it to about 4 teaspoons of rich red liquid, and injected that into his ankle. Four months later the ankle was healed. Einhorn, chair of orthopedic surgery at Boston University Medical Center, credits "adult" stem cells in the marrow injection. He tried it because of published research from France. Einhorn's experience isn't a rigorous study. But it's an example of many innovative therapies doctors are studying with adult stem cells. Those are stem cells typically taken from bone marrow and blood — not embryos.
For all the emotional debate that began about a decade ago to allow the use of embryonic stem cells, it's adult stem cells that are in human testing today.
Adult stem cells are being studied in people who suffer from multiple sclerosis, heart attacks and diabetes. Some early results suggest stem cells can help some patients avoid leg amputation. Recently, researchers reported that they restored vision to patients whose eyes were damaged by chemicals.
Apart from these efforts, transplants of adult stem cells have become a standard lifesaving therapy for many people with leukemia, lymphoma and other blood diseases.
"That's really one of the great success stories of stem cell biology that gives us all hope," says Dr. David Scadden of Harvard, who notes stem cells are also used to grow skin grafts.
"If we can re-create that success in other tissues, what can we possibly imagine for other people?"
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That sort of promise has long been held out for embryonic stem cells, which were first isolated and grown in a lab dish in 1998, creating huge controversy.
Adult cells have been transplanted routinely for decades, first in bone marrow transplants and then in procedures that transfer just the cells. Doctors recover the cells from the marrow or bloodstream of a patient or a donor, and infuse them as part of the treatment for leukemia, lymphoma and other blood diseases. Tens of thousands of people are saved each year by such procedures, experts say.
But harnessing these cells for other diseases has encouraged many scientists lately.
In June, for example, researchers reported they had restored vision to people whose eyes were damaged from caustic chemicals. Stem cells from each patient's healthy eye were grown and multiplied in the lab and transplanted into the damaged eye, where they grew into healthy corneal tissue.
A couple of months earlier, the Vatican announced it was funding adult stem cell research at the University of Maryland that focused on the intestine.
But these developments only hint at what's being explored. Much of the work is early, and even as experts speak of its promise, they ask for patience and warn against clinics that aggressively market stem cell cures without scientific backing.
Some of the new approaches, like the long-proven treatments, are based on the idea that stem cells can turn into other cells. Einhorn said the ankle repair technique, for example, apparently works because of cells that turn into bone and blood vessels. But for other uses, scientists say they're harnessing the apparent abilities of adult stem cells to stimulate tissue repair, or to suppress the immune system.
"That gives adult stem cells really a very interesting and potent quality that embryonic stem cells don't have," says Rocky Tuan of the University of Pittsburgh.
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A major focus of adult stem cell work for about a decade has been the ailing heart. While researchers remain committed, much of the early enthusiasm from patients, doctors and investors has slacked off because results so far haven't matched expectations, says Dr. Warren Sherman of Columbia University.
In treating a heart attack, for example, studies show stem cell injections help the heart pump blood a bit better, Sherman said. But the research has not yet established whether injections cut the risk of death, more heart attacks or hospitalizations.
Similarly, in congestive heart failure, research indicates stem cells can ease symptoms but larger studies are still needed to better show the value of the treatments, he said. He noted that current studies are testing stem cells not only from bone marrow and leg muscle, but also from fat.
Another heart-related condition under study is critical limb ischemia, where blood flow to the leg is so restricted by artery blockage it causes pain and may require amputation. The goal here is to encourage growth of new blood vessels by injecting stem cells into the leg.
Dr. Gabriel Lasala of TCA Cellular Therapy in Covington, La., is among a number of doctors who are reporting positive preliminary results. One success is Rodney Schoenhardt, 58, who faced losing his left leg due to ischemia.
For Lasala's research, Schoenhardt got 40 shots in each leg about 18 months ago, with stem cells going into his left calf and a placebo dose into the other. Soon, he said, the pain in his left leg was gone.
"My wheelchair is in my garage, collecting dust," he said. "I'm even thinking about taking up a little tennis again."