Islet Cell Transplants Not Cure for Type 1 Diabetes Yet

Study says improved techniques, immunosuppressants could brighten picture

WEDNESDAY, Sept. 27, 2006 (HealthDay News) -- The latest study on islet cell transplantation has both good and bad news for people with type 1 diabetes.

The good news is that nearly half of those who receive an islet cell transplant are insulin-free 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 drugs, those numbers will improve.

"A phenomenal amount of glycemic control can be provided with islet transplantation," said 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 said, "There's excitement and definite hope on the horizon. There's a robust treatment happening today in humans, not just in mice or rats."

Results of the study were expected to be published in the Sept. 28 issue of the New England Journal of Medicine.

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

For people with type 1 diabetes, Bromberg said, the glass is definitely half full as work on islet transplantation is moving forward and they're having some success. But, he said, for policymakers and health-care administrators, the glass is half empty because while there's 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."

The field of islet transplantation is relatively young, with the first real success coming just six years ago from 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," said Bromberg.

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

Thirty-six patients were involved in the current study, 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 don't 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's 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," said 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. With tweaks in protocol and changes in the anti-rejection drugs," Shapiro added, the success rate should go even higher. He noted his group is currently testing new anti-rejection drugs, something that's desperately needed because the current crop of immunosuppressants can be toxic to islet cells.

Shapiro said 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," Bromberg said.

More information

To learn more about islet cell transplantation, visit the National Institute of Diabetes and Digestive and Kidney Diseases.

SOURCES: A.M. James Shapiro, M.D., Ph.D., director, clinical islet transplant program, and Wyeth-Ayers Canada/CIHR clinical research chair in transplantation, University of Alberta, Edmonton, Canada; Jonathan Bromberg, M.D., Ph.D., professor, surgery, immunobiology and gene and cell medicine, surgeon-in-chief and director, transplant institute, Mt. Sinai School of Medicine, New York City; Sept. 28, 2006, New England Journal of Medicine
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