April 10, 2007 -- An injection of stem cells could one day serve as a therapy for diabetes, a new study suggests, demonstrating yet another application for the versatile stem cell approach.
In the current issue of the Journal of the American Medical Association, a small Brazilian study reports that injections of stem cells harvested from a patient's own blood may keep type 1 diabetes at bay. The type 1 form of diabetes accounts for 5 to 10 percent of the approximately 21 million Americans with the disease.
The injections work by using the patient's own stem cells to replace the defective cells that cause the disease.
The study's findings could bring new hope to patients with type 1 diabetes because "for the first time in the history of diabetes, patients are now treatment-free for up to three years," says Dr. Richard Burt, the senior author of the study and chief of the division of immunotherapy at Northwestern University's Feinberg School of Medicine.
But some diabetes experts say more research is needed to confirm the benefits.
Dr. Jay Skyler, associate director of the Diabetes Research Institute in Miami and author of an accompanying editorial to the study, cautions that the study "is pioneering and provocative, but it is too small a number and too short a duration to allow people yet to change. … It needs confirmation."
And since the treatment involves destroying the patient's immune system before the patient receives the stem cells, critics fear the risks of the treatment may outweigh its potential benefits.
When Immune Cells Attack
Type 1 diabetes is caused by the destruction of the insulin-producing cells in the pancreas by a person's own immune cells -- what Burt calls the "police force" of the body.
The disease is usually diagnosed in childhood or adolescence. Patients normally face a lifelong regimen of insulin replacement, either through a continuous pump or frequent self-administered insulin shots.
Insulin is critical to how the body uses sugar. Without it, unused sugar, or glucose, builds up in the body.
Over the long term, chronically high levels of glucose can damage the eyes, heart, kidneys and nerves -- possibly resulting in blindness, heart disease, kidney failure and loss of sensation.
Currently, there is no cure for type 1 diabetes, and onIy strict control of glucose levels can reduce the complications of this disease. But Burt and his colleagues hope that these stem cell injections could be a first step.
Though this is the first time researchers have used this particular stem cell approach for diabetes, such injections have been found to be promising in the treatment of many other diseases in which the immune system attacks the patient's own body, such as rheumatoid arthritis and multiple sclerosis.
First, doctors collect the patient's own stem cells from his or her blood. They then destroy the patient's existing immune cells with chemicals, after which they use the harvested stem cells to rebuild the patient's immune system.
Unlike the old immune cells, the new ones will not attack the insulin-producing cells in the pancreas -- or at least, that's what researchers hope.
Too Little, Too Early
But is this study good enough? Skyler cautions that the research is limited by three things: small numbers, short duration and no control group.
The study looked at just 15 patients recently diagnosed with type 1 diabetes. While in this study all the patients survived, and 14 of 15 patients were insulin-free for one to 36 months, even the study's senior author admits the study has its limitations.
"I would never use the word 'cure,'" Burt says. "There is a lot more time in which this study needs to be followed."
The study also looks only at treating a very select group of patients -- those who have had a diagnosis of type 1 diabetes for less than six weeks. It remains to be determined whether the treatment can provide benefits for all people who have type 1 diabetes -- or even lasting results for those who get it.
Despite the weaknesses of the study, however, its results are intriguing and warrant further research, says Dr. Larry Deeb, president of the American Diabetes Association.
"[Type 1 diabetes] is the kind of diabetes that most kids get," Deeb says. "If this [treatment] were to be very effective, there would be no more new diabetes. If you stop type 1 diabetes, that would be very important."
Is the Treatment Too Risky?
The treatment is not without its risks. Critics of the study say destroying the immune system -- the body's main defense against infection -- has big implications.
Even though the patient's immune system is the cause of the disease, removing it even temporarily can bring about significant side effects, such as fevers, low white blood cell counts, nausea, vomiting and hair loss.
The treatment also presents a threat of serious infections, although in the study only one of 15 patients developed such an infection and was successfully treated with antibiotics.
But there is also a risk of death.
"I would expect the risk of death will be less than 1.3 percent, and I think you could do it for less than a 0.5 percent risk of death," Burt says. "There is a risk-to-benefit in everything."
However, Dr. Michael Haller, assistant professor of pediatric endocrinology at the University of Florida, and Dr. Desmond Schatz, associate chairman of pediatrics at the University of Florida College of Medicine, argue, "This particular therapy is associated with an unacceptably high risk for complications and even death." They add that conservative estimates of death and other serious complications from this treatment would be between 1.5 and 3 percent.
Stem cell transplantation "is a pretty significant immunologic intervention, and you have to be humbled by the patients who are willing to take these risks and be involved in this study."
But many patients may be willing to take the risk.
"It's a very personal decision," said one patient, who participated in the study in a translated e-mail message. "Each patient has to balance the pros and cons and decide what is best for him."
As for side effects, the patient, who preferred his name not be released, said, "I am not concerned with them. I am aware of the known side effects. The unknown, only time will tell me."
Former ABC News Medical Unit intern Dr. Mark Abdelmalek contributed to this report.