Spleen Cells Fail to Treat Diabetes
But Insulin-Making Islet Cells Can Recover in Type 1 Diabetes
March 23, 2006 -- It seemed too good to be true. And it was. Three new studies dash hopes that type 1 diabetes.
could help reverse
But there's a silver lining. Or, rather, an islet-cell lining. The new studies show that the most important part of the earlier study is true. Some of the insulin-making islet cells lining the pancreas can recover.
This means that if scientists find a way to stop the haywire immune responses that destroy islet cells and cause type 1 diabetes, a patient could be freed from the need for insulin injections. No spleen cells needed.
The new studies show this can be done in mice with type 1 diabetes. And it's possible for humans, suggests Emil R. Unanue, MD, head of the departments of pathology and immunology at Washington University, St. Louis. Unanue [pronounced ew-NAN-uh-way] led one of the three new studies reported in the March 24 issue of Science.
"There is a window of time, soon after an individual loses blood-sugar control, when there is still [islet]-cell function in the pancreas," Unanue tells WebMD. "If at that time you stop the [harmful] immunologic process, you can rescue a level of insulin function that allows the individual to be free of the need for insulin therapy."
How to Cure Type 1 Diabetes
It's going to take two steps to cure type 1 diabetes. The first step is to stop the body's immune system from attacking islet cells. The second step is to get some new islet cells -- by letting surviving cells grow and multiply, by transplanting donor cells, or by encouraging stem cells to become new islet cells.
In 2003, Massachusetts General Hospital researcher Denise Faustman, MD, PhD, and colleagues apparently found a way to do this -- in mice.
They used an immune-boosting substance called CFA that drives hyperactive anti-islet immune cells to suicide. This put destructive immune responses on hold. Then they gave the mice temporary islet-cell transplants to tide them over until they could grow new islet cells. Finally, they gave the mice repeated injections of spleen cells from other mice. It seemed that these spleen cells gave rise to new islet cells.
Unanue's team at Washington University, a team led by Louis Philipson, MD, PhD, at the University of Chicago, and a team led by Diane Mathis at Harvard's Joslin Diabetes Center all tried to repeat the Faustman experiment.
It didn't work. None of the three teams got the same result. The spleen cells, it turns out, didn't become islet cells.
That means the mice should have died once their temporary islet transplants were removed. But a few of them didn't die. Instead, their islet cells recovered and began making enough insulin to keep the animals alive.