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 | | One in every 400 to 600 children and adolescents has type 1 diabetes |
The Most Promising Cure
Islet Transplantation
Researchers are working on a way for people with type 1 diabetes to live without daily insulin injections. In an experimental procedure called islet transplantation, islets are taken from a donor pancreas and transferred into a person with type 1 diabetes. Once implanted, the beta cells in these islets begin to make and release insulin.
Scientists have made many advances in islet transplantation in recent years. Since reporting their findings in the June 2000 issue of the New England Journal of Medicine, researchers at the University of Alberta in Edmonton, Alberta, Canada, have continued to use a procedure called the Edmonton protocol to transplant pancreatic islets into people with type 1 diabetes. Before use of the Edmonton protocol, during the 1990s, less than ten percent of islet cell transplant recipients were able to control blood glucose levels for more than one year without insulin injections.
The Collaborative Islet Transplant Registry (CITR), funded by NIDDK, was created in 2001. CITR’s mission is to expedite progress and promote safety in islet transplantation by collecting, analyzing, and communicating data on islet transplantation. The CITR will study islet transplantation alone as well as islet transplantation following kidney transplant.
The September 2005 CITR annual report noted that with use of the Edmonton protocol, after 1 year, 58 percent of those who had transplants no longer needed to inject insulin. Of those who were still insulin-dependent 1 year after transplantation (33 percent of those followed by the registry), requirements for insulin were decreased. The average reduction in insulin requirements was 69 percent. In summary, a total of 91 percent of those with transplants showed improvement following transplantation. The success of the Edmonton protocol has been confirmed at other study sites, including the NIDDK.
The goal of islet transplantation is to infuse enough islets to control the blood glucose level without insulin injections. For an average-sized person (154 pounds), a typical transplant requires about 1 million islets, extracted from two donor pancreases. Because good control of blood glucose can slow or prevent the progression of complications associated with diabetes, such as nerve or eye damage, a successful transplant may reduce the risk of these complications. However, transplanted islets lose their ability to function over time. Also, a transplant recipient needs to take immunosuppressive drugs to stop the immune system from rejecting the transplanted islets.
These drugs have significant side effects, and their long-term effects are still unknown. Immediate side effects of immunosuppressive drugs may include mouth sores and gastrointestinal problems, such as stomach upset or diarrhea. Patients may also have increased blood cholesterol levels, decreased white blood cell counts, decreased kidney function, and increased susceptibility to bacterial and viral infections. Taking immunosuppressive drugs increases the risk of tumors and cancer as well. Researchers are trying to find safer or less toxic immunosuppressants or new approaches that will allow successful transplantation without the use of immunosuppressive drugs.
The results of the Edmonton protocol are very encouraging, but more research is needed to develop safer and more effective immunosuppression and to enhance islet survival after transplantation.
Another obstacle to widespread use of islet transplantation is the severe shortage of islets. Only about 6,000 pancreases a year become available for transplantation or for harvesting of islets. However, researchers are pursuing alternative sources, such as creating islets from other types of cells. New technologies could then be employed to grow islets in the laboratory.
Islet Transplantation at The University of Virginia
In 2002, the University of Virginia Health System created the Center for Cellular Transplantation and Therapeutics
and established the first human islet cell transplant program in the Commonwealth of Virginia. The center has performed
two islet cell transplants and can now isolate insulin-producing tissue from human pancreata for transplantation into
diabetic patients.
Visit the UVa Health
System Transplant Program Web site for more information.
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