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Similarly, in heart failure, research indicates stem cells can ease symptoms but larger studies are still needed to show how much good the treatments provide, he said. He noted that current studies are testing stem cells taken 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.
Sherman said limb ischemia research is moving fast and the results "are very, very encouraging."
The injected cells may serve as building blocks while also stimulating local tissue to grow the vessels, said Dr. Douglas Losordo of Northwestern University. His own preliminary work suggests such a treatment can reduce amputation rates.
Dr. Gabriel Lasala of TCA Cellular Therapy also has reported positive preliminary results. One success is Rodney Schoenhardt of Metairie, La.
Schoenhardt had already had surgery on both legs for the disease, and his surgeon was talking about amputating his left leg. Schoenhardt suffered so much pain in his left leg while standing that he used a wheelchair instead.
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.
Schoenhardt, 58, now mows his lawn, and he remodeled his living room to fix damage from Hurricane Katrina. "My wheelchair is in my garage, collecting dust," he said.
"I'm even thinking about taking up a little tennis again."
With all the heart-related stem cell studies, the former president of American Heart Association says, "We should be enthusiastic, but cautiously so." Beyond the promising indications of early studies, researchers need definitive evidence that the treatments not only make patients better but also don't cause unintended harm, says Dr. Clyde Yancy.
Among the other diseases being studied for stem cell treatments:
Multiple sclerosis. In MS, the body's immune system repeatedly assaults brain and spinal cord tissues, which can cause numbness in the limbs, paralysis or vision loss.
Last year, Dr. Richard Burt of Northwestern reported a small trial in patients with early MS that was aimed at rebooting the immune system to stop the attacks. He removed stem cells from the patient's blood, destroyed their immune systems, and then re-injected them with their own cells to build a new immune system.
To his surprise, most patients actually improved. He's now conducting another trial to provide firmer evidence of improvement.
Dr. Jeffrey Cohen of the Cleveland Clinic is trying a different and less-researched approach. In a preliminary trial he is just starting, he'll use a different kind of stem cell from patients' marrow that he hopes can slow nervous system damage but also promote repair.
Lessons learned from this approach might eventually reveal some clues for treating other conditions like Parkinson's or spinal cord injury, he said.
Type 1 diabetes. It's also caused by a misguided attack by the immune system, this time on insulin-producing cells. Burt and colleagues reported last year that the "rebooting" strategy allowed some patients to go without insulin for four years. However, some experts call his approach too risky for that disease. Burt is now doing another study in newly diagnosed adults.
Another study, at about a dozen medical centers around the country, is testing whether an off-the-shelf preparation of marrow stem cells can calm the immune system of diabetics. It's still early work, says C. Randal Mills, chief executive officer of Osiris Therapeutics.
Cancers such as melanoma and kidney cancer. The idea is to transplant cells to produce a new immune system that will attack the diseases. Earlier work around a decade ago failed to give lasting benefit, but new approaches aim for better results, said Dr. Michael Bishop of the National Cancer Institute.
Even as scientists hope adult stem cells will produce new treatments, they are concerned about clinics that make claims about unproven stem cell therapy.
"Clinics have sprung up all over the world ... that are essentially selling snake oil, that are preying on the hopes of desperate patients," said Sean Morrison, a stem cell expert at the University of Michigan.
Morrison suggests patients consult their own doctors about going to a clinic.
Stem cell clinic website:
General stem cell information:
Adult stem cells:
Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
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