Islet cell transplant: Experimental treatment for type 1 diabetes
An islet cell transplant provides you with new insulin-producing cells from a donor pancreas. Learn what to expect of this experimental transplant procedure, the surgery itself and follow-up care.
Type 1 diabetes is a condition in which your pancreas produces little or no insulin, a hormone that allows sugar (glucose) to enter your cells. Treatment for type 1 diabetes is a lifelong commitment of monitoring blood sugar, taking insulin, eating healthy foods and maintaining a healthy weight. For some people, however, insulin therapy and healthy lifestyle choices aren't enough.
If you have severe type 1 diabetes that can't be managed with insulin therapy, you might be a candidate for an islet cell transplant. With this experimental transplant procedure, only the insulin-producing islet cells from a donor pancreas — not the entire organ — are transplanted into your body.
How does the pancreas lose its ability to produce insulin?
The pancreas releases enzymes into your small intestine to break down nutrients. It also releases hormones into your bloodstream to help your body use glucose. One of these hormones, insulin, lets glucose enter your cells. Glucose is a main source of energy for the cells that make up your muscles and other tissues.
Throughout the pancreas are clusters of specialized cells that produce insulin. When you have type 1 diabetes, your immune system — which normally protects you from viruses and bacteria — attacks and kills these cells. This may occur through a combination of factors, including a genetic predisposition or exposure to certain viruses.
Without insulin, glucose can't get into your cells. Lack of insulin can lead to potentially fatal complications. High blood sugar, which can eventually damage your blood vessels and other tissues, is a particular concern. Your eyes, nerves and kidneys are particularly susceptible to this damage.
Who might be considered a candidate for an islet cell transplant?
An islet cell transplant may be an option if you have complications of type 1 diabetes or severe type 1 diabetes that can't be effectively managed with insulin. But the treatment isn't widely available. If you live in the United States, where islet cell transplants are considered experimental, getting one usually means participating in a clinical trial and waiting for a donor pancreas.
The lack of suitable donor pancreases is a major obstacle in the widespread use of islet cell transplants. Researchers are studying other options, however, such as harvesting islet cells from living donors or animals.
What happens during the transplant?
An islet cell transplant begins in a lab, where technicians extract and purify islet cells from a donor pancreas. Often, two or more donor organs are needed to accumulate enough islet cells for a single complete transplant.
During the transplant, the surgeon directs a tube through an opening made in your abdomen to the portal vein, a blood vessel leading into your liver. He or she then infuses the islet cells through this tube to your liver, where they take up residence in the organ's small blood vessels. The liver is a good site for the islet cell transplant because it's more accessible than your pancreas, and the cells appear to produce insulin well in that environment.
Most islet cell transplants are complete in less than an hour, followed by about two days in the hospital. Sometimes the infusions need to be repeated, which requires subsequent hospital stays and additional donor organs. Possible risks of the procedure include bleeding and blood clots.
What can I expect after the transplant?
Your new islet cells may need time to start working. The transplant team will closely monitor your blood sugar level and give you insulin as needed. If the transplant is successful, the amount of insulin you need will be gradually reduced as the new cells take over.
Because your immune system will try to reject the new cells, you'll need to take medications that suppress your immune system. Some of these medications may cause noticeable side effects, such as mouth sores, acne, diarrhea, nausea, vomiting and fatigue. You'll be more susceptible to viral and bacterial infections. Other serious concerns include increased blood cholesterol levels, high blood pressure, decreased kidney function, and an increased risk of tumors and certain types of cancer.
Your post-transplant treatment will be a delicate balancing act between preventing rejection and managing unwanted side effects. Your doctor will monitor your treatment closely and adjust it as needed.
What are typical success rates?
At first, few islet cell transplants were successful. Short-term outcomes improved by increasing the number of transplanted cells and modifying the approach to immune-suppressing medications.
In a study of 36 islet cell transplant recipients published in 2006, more than 40 percent of participants were off insulin therapy completely within one year of the last infusion of islet cells. By three years, 17 percent of transplant recipients remained free of insulin therapy.
In a study of 65 islet cell transplant recipients published in 2005, only 10 percent of participants remained off insulin therapy five years after the last infusion of islet cells. Many participants were able to use less insulin than before the transplant, however, and maintain better control of their blood sugar.
Keep in mind that success can be measured in various ways. Even if an islet cell transplant doesn't lead to long-term blood sugar control, severe insulin reactions are less likely after the procedure.
What if the transplant fails?
An islet cell transplant offers no guarantees. Your immune system may reject the foreign cells, the new cells may not survive in your liver, or recurring diabetes-related events may destroy the cells. If the islet cells don't survive, you'll need to resume insulin treatments.
If you have an islet cell transplant, you'll be contributing to a growing body of knowledge about the safety and effectiveness of this treatment — whether your transplant is successful or not. Your participation may help other people who are managing type 1 diabetes today or who may face it in the future.
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