Apr 10, 2007
Diabetics appear to have been cured with a one-off treatment that rebuilds their immune system, according to a new study.
The technique, which uses patients' own bone marrow cells, has freed 14 of 15 patients with type 1 diabetes from their dependence on insulin medication.
So far, participants in the trial have gone 18 months without insulin therapy following the procedure, on average. One patient has lasted three years without needing such injections.
In patients with type 1 diabetes, which typically strikes in early childhood or adolescence, the immune system appears to erroneously attack cells in the pancreas that produce the hormone insulin. Without insulin, blood sugar levels in the body spiral out of control. People with diabetes receive insulin therapy, often in the form of self-injected shots, to keep their blood sugar levels under control.
Scientists have speculated that "resetting" the immune system might stop it from attacking the insulin-producing cells in the pancreas.
Julio Voltarelli, at the University of Sao Paulo in Brazil, and colleagues recruited 15 people aged 14 to 31 years who had recently been diagnosed with type 1 diabetes. Roughly 60% to 80% of these patients' insulin-producing cells had been destroyed by the time of their diagnosis, and all needed regular insulin shots.
The researchers removed bone marrow stem cells from the patients, who were then given drugs such as cytotoxan to wipe out their immune cells. Without an immune system, the patients were vulnerable to infection and so they were given antibiotics and kept in an isolation ward. They participants did not undergo radiation treatment – as leukaemia patients often do as part of a bone marrow transplant – and so had fewer side effects and less risk of organ damage.
Two weeks later, the patients received infusions of their own stem cells into their bloodstream via the jugular vein, which re-established their immune systems.
Throughout this time and following the stem cell transplant, the research team continued taking blood samples to assess how much insulin each patient required.
Of the 15 patients, 12 no longer needed insulin shots within a few days of undergoing the procedure. One patient from the group had a relapse and needed to take insulin for one year, before becoming insulin-independent again – and has remained this way for 5 months.
Of the remaining two participants, one stopped needing insulin shots for one year after the transplant but has spent the past two months back on the shots, and the final participant's diabetes did not respond to the stem cell treatment.
Those who responded to the treatment have not needed insulin shots – so far, for an average 18 months – and had not relapsed at the time of study publication. One patient had gone as long as 35 months without needing insulin therapy. "It may be that they become insulin-free for life. We don't know," says Voltarelli.
Exactly why some patients responded to the treatment and one did not remains a mystery. "It could be due to differences in genetic background or severity of the immune attack," Voltarelli suggests.
During the course of the trial, one patient developed pneumonia as a result of the immune-suppressing drugs used in the procedure. Two others developed complications, including thyroid dysfunction and early menopause, but it is not clear if these relate to the stem cell transplant
Jay Skyler, who heads the Diabetes Research Institute at the University of Miami in Florida, US, cautions that the trial did not include a control group. Skyler adds some people experience a remission of symptoms shortly after being diagnosed with type 1 diabetes, and the increase in insulin production seen among study participants might be related to this "honeymoon period".
Skyler also notes it is unclear exactly how the insulin production in the patients increased.
Still, he says that the trial has "shown some potentially promising results". And Voltarelli is hopeful that this type of approach could help patients with type 1 diabetes avoid some of the long-term complications that arise from the illness, such as kidney, eye and nerve damage, which result from chronically high levels of blood sugar.