Scientists Report Transplant Advance for Type 1 Diabetes

Used in single patient, special chamber may allow implantation of insulin-producing cells without rejection

By Serena Gordon

HealthDay Reporter

MONDAY, Oct. 28 (HealthDay News) -- Using a specially designed chamber, an international research team has transplanted islet cells into a patient with type 1 diabetes.

The new technique avoided having to use immune-suppressing medications, while still allowing the islet cells to function and make insulin. In theory, the chamber "hid" the transplanted islet cells from the patient's immune system, the researchers explained.

Islet cells are normally found in the human pancreas. One critical function of these cells is producing insulin -- a hormone crucial for metabolizing the carbohydrates in food. In people with type 1 diabetes, an autoimmune disease, the islet cells have been destroyed by the body's own immune system.

"In order to transplant replacement cells, heretofore, the immune response to the foreign cells has had to be controlled with immunosuppression," explained study co-author Dr. Norman Block.

Now, he said, senior study author Dr. Stefan Bornstein "has found a way to implant foreign cells and protect them without using immunosuppression" -- drugs to dampen the immune system.

Medications used to suppress the immune system can come with significant risks and side effects.

The study was released online Oct. 28 in the Proceedings of the National Academy of Sciences.

Because their bodies lack working islet cells, people with type 1 diabetes no longer produce enough insulin to survive. They must take daily insulin injections or receive their insulin through a small catheter underneath the skin that's attached to an insulin pump.

Maintaining the proper levels is a difficult task. Too much insulin, and blood sugar levels can drop to dangerously low levels that at their worst can cause seizures and even death. Too little insulin, and blood sugar levels run high. Over time, these high levels can put someone with diabetes at risk of complications, such as vision problems and kidney disease.

Needed levels of insulin vary from person to person, and according to the types of food someone eats, how much they eat, how much they exercise and what type of stress they face.

Because islet cells can currently only be transplanted with the use of immune-suppressing drugs, the implant procedure is limited to patients who have difficult-to-control diabetes and experience repeated episodes of life-threatening low blood sugar levels. Immune-suppressing drugs have potential side effects, including the risk of infection and certain cancers.

To try to make the implant procedure available to more people, the researchers designed a semi-permeable chamber to house the islet cells, with the hope that the immune system wouldn't be able to "see" the new foreign cells.

However, when islet cells are first transplanted, they haven't established their own blood supply and aren't able to get oxygen when they're hiding in the chamber. For that reason, the current version of the device had an oxygen port on the outside of the body attached via tubing that had to be refilled daily by the patient for as long as a month or two, Block explained.

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New Drug May Someday Battle Obesity and Diabetes

Mouse studies found it did double duty; human trials too short to see effect, researchers report

By Dennis Thompson

HealthDay Reporter

WEDNESDAY, Oct. 30 (HealthDay News) -- A new diabetes drug may one day perform double duty for patients, controlling both their blood sugar levels and helping them lose weight, researchers report.

In mouse trials, doctors found the drug prompted weight loss, in addition to managing blood sugar levels.

"That [weight loss] is not what this drug was designed to do, but it's a very attractive additional benefit," said study co-author Richard DiMarchi, a research chemist at Indiana University in whose lab the drug was created.

The injectable medication is based on a single molecule that combines the properties of two hormones that send chemical signals to the pancreas, said DiMarchi.

"They signal to the pancreas that you are taking a meal," DiMarchi said. "The pancreas then responds by secreting insulin and to synthesize additional amounts of insulin for subsequent use."

People with type 2 diabetes have lower levels of these pancreas-signaling hormones, which are known as incretins, explained Dr. John Anderson, president of medicine and science at the American Diabetes Association.

"The incretin defect in type 2 diabetes is well known, and it's only within the last few years we have had agents to treat it," Anderson said.

Human and primate trials revealed that the new drug controls blood sugar with fewer side effects than other diabetes medications. Those side effects can include nausea, vomiting and stomach pain.

"In this study, the degree of gastrointestinal discomfort is much more modest than is experienced in conventional drugs," DiMarchi said. "We get beneficial glycemic control with this combination drug, and it seems to be with less adverse drug effect."

The medication combines the action of the hormones GLP-1 and GIP. Current diabetes medications of this sort target GLP-1 receptors in the body; studies involving GIP have produced mixed results.

GLP is known to suppress appetite, and DiMarchi said the weight loss observed in mice might be occurring because the second hormone, GIP, is somehow "turbo-charging" that appetite suppression.

In the mouse trials, a drug based on GLP-1 alone decreased body weight by an average 15 percent. But the new drug combining GLP-1 and GIP decreased body weight by nearly 21 percent, as well as controlling blood glucose and decreasing appetite.

A six-week human trial involving 53 patients with type 2 diabetes found that the medication effectively controlled their blood sugar levels. However, the researchers did not note any change in weight during the relatively short study period.

The higher potency of the combined molecule suggests it could be administered at lower doses than other incretin-based medications, reducing side effects and making the drug easier to take.

"Currently approved drugs are quite effective," DiMarchi said, "but they are insufficient in normalizing glucose, and they certainly don't cause much loss of body weight."

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