Islet cell transplant: Experimental treatment for type 1 diabetes
An islet cell transplant provides you with new insulin-producing cells from a donor pancreas. Know what to expect of this experimental transplant procedure, the surgery itself and follow-up care.
Your pancreas releases enzymes into your small intestine to break down nutrients. It also releases hormones into your bloodstream to help your body use sugar (glucose). One of these hormones, insulin, lets glucose enter your cells.
When your body is unable to regulate the amount of glucose in your blood, you may have diabetes. Type 1 diabetes occurs because your pancreas produces little or no insulin. In type 2 diabetes, your pancreas produces insulin, but your body doesn't use that insulin efficiently.
An experimental procedure called an islet cell transplant may be a treatment option for some people with type 1 diabetes. With this transplant procedure, only the insulin-producing cells from a donor pancreas — not the entire organ — are transplanted into your body.
How does the pancreas lose its insulin-producing function?
Throughout the pancreas are clusters of specialized cells that produce insulin. In type 1 diabetes, the body's immune system, which normally protects the body from viruses and bacteria, attacks and kills these cells. This may occur through a combination of factors, including a genetic predisposition, diet or exposure to certain viruses.
Without insulin, glucose can't get into your body's cells. Lack of insulin can lead to potentially fatal complications. High blood sugar — which can eventually damage your blood vessels and other tissues — is another concern. Your kidneys are particularly susceptible to this damage.
Who might be considered for an islet cell transplant?
An islet cell transplant may be an option if you have severe type 1 diabetes that can't be effectively managed with insulin or leads to complications. Because the procedure is still considered experimental in the United States, getting it usually means participating in a clinical trial.
If you're accepted into a trial, you'll need to wait for a donor pancreas. Available organs are first allocated to people waiting to receive whole pancreas transplants. If a match can't be made, an organ is then allocated to a person on the islet cell transplant list.
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.
A specialist called an interventional radiologist performs the actual islet cell transplant. The radiologist 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.
Possible risks include bleeding or 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 weight gain, acne, facial hair, stomach upset or diarrhea. These effects may decrease as time goes on.
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.
As a clinical trial participant, you'll be expected to follow a well-regulated diet and document your self-assessments and medication use after you're released from the hospital. You'll also need follow-up assessments throughout the trial.
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. However, the latest long-term success rates are disappointing.
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 transplant. By two years, however, less than 14 percent of transplant recipients remained free of insulin therapy.
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.
Whether your islet cell transplant is successful or not, you'll be contributing to a growing body of knowledge about the safety and effectiveness of this treatment. Your participation may help other people who are managing the disease today or who may face it in the future.