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Islet Cell Therapy for Type 1 Diabetes Makes Progress

There is both good and bad news for people with type 1 diabetes who receive islet cell transplantation, according to a study in the New England Journal of Medicine.

The good news is that nearly half of those who receive an islet cell transplant no longer required insulin injections at one year after transplant. The bad news is that by the end of the second year that number drops to about one in seven.

Still, researchers expect that with improvements in the technical aspects of the procedure, and better anti-rejection medications, those numbers will improve.

The procedure involves collecting about 1 million islet cells from a donor pancreas, purifying the cells, and then injecting them into the liver of someone with type 1 diabetes.

"A phenomenal amount of glycemic [blood sugar] control can be provided with islet transplantation," says study author Dr. A.M. James Shapiro, director of the clinical islet transplant program at the University of Alberta in Edmonton, Canada.

For people with diabetes, he says, "There's excitement and definite hope on the horizon. There's a robust treatment happening today in humans, not just in mice or rats."

Functioning Islet Cells Needed for Insulin

About five percent to ten percent of the estimated 21 million Americans with diabetes have Type 1 diabetes - an autoimmune disease in which the body loses its ability to make insulin due to destruction of islets.

Islets are clusters of cells in the pancreas that produce insulin, a hormone the body requires to use glucose (sugar) as a source of energy.

This is different from the more common Type 2 diabetes, in which the body produces insulin but has a reduced ability to use it properly.

Without insulin, very high levels of glucose accumulate in the blood, causing injury to nerves and blood vessels; at the same time, the glucose is unable to enter cells where the body can use it. Without insulin injections, this condition is fatal.

Even with insulin injections, people with Type I diabetes cannot achieve perfectly normal control of their blood sugar. As a result, most people with Type 1 diabetes eventually develop one or more complications, such as heart disease and damage to the eyes, nerves, and kidneys.

Dr. Jonathan Bromberg, who directs the transplant institute at Mt. Sinai School of Medicine in New York City, says of the new study, "You can look at this as the glass being half full or half empty."

For persons with type 1 diabetes, says Dr. Bromberg, the glass is definitely half full as work on islet transplantation is moving forward and they are having some success.

But, he says, for policy makers and healthcare administrators, the glass is half empty. Dr. Bromberg says that while there has been modest success for islet transplants, "They have to try to figure out if this is the best way to spend limited health-care dollars vs. doing screening and more intensive diabetes care to a large number of patients."

In the last few decades, physicians have been able to treat Type 1 diabetes with pancreas transplantation.

The transplanted pancreas senses blood sugar and produces insulin. Many people with diabetes who have taken daily insulin injections for years have achieved total insulin independence after pancreas transplantation - often for years after the transplant.

About 1,500 pancreas or pancreas/kidney transplants are performed every year in the US, and nearly 20,000 of these operations have been performed in the last two decades.

The field of islet transplantation is relatively young, with the first real success coming just six years ago from Dr. Shapiro's group in Edmonton.

"Up until the first Edmonton study came out, islet transplantation had been in the doldrums for a decade and a half," notes Dr. Bromberg.

The procedure used by the Canadian researchers for that study was so successful that it has been dubbed the Edmonton protocol.

Advances Will Continue, Experts Say

In the current study, thirty-six patients were involved and to be included, they needed to have tried and failed standard diabetes treatments and had to have severe, recurrent episodes of low blood sugar (hypoglycemia).

The volunteers underwent islet transplantation at one of nine international centers. The islets came from deceased donors, and all were transplanted within two hours of being harvested.

As with other transplants, patients have to take immune-suppressing medications so their bodies do not reject the foreign cells.

After one year, 16 people (44 percent) were insulin-free. Another 28 percent had partial glycemic control from the functioning islets, while the remaining 28 percent had what is known as complete graft loss after a year. That means the transplanted cells were no longer functioning.

Of the 16 who were able to get off insulin for a year, five were still insulin-free at the end of two years.

"Overall, the results are impressive," says Dr. Shapiro. "The most important thing is to recognize that this is the first ever multinational trial to be done on islet transplantation. Some sites had never done this before."

"This field can be improved,” he adds. “With tweaks in protocol and changes in the anti-rejection drugs," the success rate should go even higher.

He says his group is currently testing new anti-rejection medications, something that is desperately needed because the immunosuppressants that are currently available can be toxic to islet cells.

Dr. Shapiro says the issue of supply is going to be another problem that will have to be addressed as the technique improves and more people are transplanted.

"There's a lot of hope that islet transplantation may change the lives of people with diabetes, but a bigger picture view is that there are a lot of modalities available for treating diabetes today - insulin pumps, semi-synthetic insulins and more - all of which are improving the lives of diabetics," says Dr. Bromberg.

Always consult your physician for more information.