Unique cell prevents diabetes

By STEVE MITCHELL, Medical Correspondent  |  April 29, 2002 at 5:38 PM
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WASHINGTON, April 29 (UPI) -- A unique type of cell prevents the development of diabetes in mice and a genetically manipulated version of the cell might do the same in humans, researchers reported on Monday.

"If we can put the same types of cells into humans, we might be able to prevent diabetes," John J. Fung, a surgeon at the University of Pittsburgh School of Medicine, told United Press International.

Working with mice, Fung and his colleagues identified a type of cell called a dendritic cell that has the ability to turn off components of the immune system. When researchers injected dendritic cells into mice prone to developing a form of diabetes very similar to type 1 human diabetes, none of the animals developed the condition within the first several months. Half remained disease-free at one year.

In contrast, all the mice not receiving the cell injection developed diabetes within 5 months, said Fung, who presented his research at the American Transplant Congress.

"It is a novel approach ... and a nice finding," Camillo Ricordi, a professor of medicine and scientific director of the Diabetes Research Institute at the University of Miami, told UPI. "But I'd greet it with cautious optimism ... because there have been a lot of techniques that have prevented diabetes in mice that haven't transferred to humans," added Ricordi, who was not involved in the research.

The reason the dendritic cells, whose technical name is B220+DC, prevented diabetes is that the type I or juvenile onset version results from an autoimmune condition. The body's immune system destroys insulin-producing islet cells, Fung explained. By turning off T-cells, the cells in the immune system that attack islet cells in diabetes, the dendritic cells prevented the mice from developing the disease.

Despite the success in mice, Fung said it would be difficult to move immediately to a therapeutic treatment in humans because the dendritic cells are only found in the liver, so it probably would not be feasible to gather enough of the cells to treat a large number of people.

In a second study, Fung and his team set out to determine whether it would be possible to create cells that could mimic the diabetes-preventing effects of dendritic cells. They took a different type of dendritic cell found in bone marrow and genetically modified it to behave like the liver's dendritic cells.

When injected into diabetic prone mice, the modified cells were not nearly as effective as the original dendritic cells in preventing diabetes. But they did delay development of the condition in many animals and provided encouragement that modified cells could be developed that prevent diabetes, Fung said.

The next step toward making this a viable treatment for preventing diabetes in humans is to identify the dendritic cells in people, Fung said. Dendritic cells exist in humans but researchers do not yet know if we carry the particular type that prevents diabetes, he said.

Fung's team has already begun searching for dendritic cells in monkeys. If they are found in primates, they will be easier to find in humans because they should have similar identifying characteristics, he said.

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