Islet cell transplants are a promising experimental treatment for difficult to control type 1 diabetes. It involves the transplantation of pancreatic islet cells to help improve blood glucose levels. Future research could help make these treatments more available.

In the United States, diabetes is the seventh-ranking cause of death. The two main types of diabetes are known as type 1 and type 2. Type 1 diabetes is far less common than type 2, accounting for roughly 5–10% of people living with diabetes.

Type 1 diabetes is an autoimmune condition where the immune system mistakenly attacks the pancreas and destroys the cells that produce the hormone insulin. This chemical messenger is responsible for regulating blood sugar. There is currently no cure, but people can manage the condition by manually administering insulin themselves.

Islet cell transplants involve the transfer of insulin-producing cells from a donor that may be able to replace the destroyed cells. The procedure might help people with type 1 diabetes to live without daily insulin injections.

In this article, we discuss how the islet cell transplantation procedure works and why it may be a future treatment option for type 1 diabetes.

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The pancreas is a specialized organ located in the abdomen. It is known as a heterocrine, or mixed gland, as it possesses both exocrine and endocrine functions. Its exocrine function involves producing juices that aid in digestion. Its endocrine function involves a group of cells known as the islets of Langerhans, or islet cells.

The islets of Langerhans consist of different cell types, with many being responsible for the production and release of hormones that regulate glucose levels. One of the most studied islet cell types is beta cells, which secrete insulin in response to a high concentration of glucose in the blood.

A characteristic feature of type 1 diabetes is the autoimmune destruction of these insulin-producing beta cells. Lack of these cells results in insulin insufficiency and can lead to hyperglycemia. People living with type 1 diabetes require insulin therapy to maintain glycemic control. They also need to regularly monitor their blood sugar to avoid a hypoglycemic episode.

An islet cell transplant is a medical procedure that involves the transfer of healthy beta cells from a donor. A medical professional will purify, process, and transfer these cells shortly after removal from the donor. Typically, a person will receive at least 10,000 islet equivalents per kilogram of body weight from two donor pancreases.

Most of these procedures involve the use of a catheter or thin tube. A medical practitioner, often a radiologist, uses X-rays and ultrasound to help guide the insertion of this tube into the portal vein of the liver or another suitable site. They slowly transfer the donated islet cells through the catheter. The islet cells then become lodged in the blood vessels of the liver. After about 2–6 weeks, the cells become active and start producing insulin.

During the transplant, the individual will take immunosuppressants to help prevent their immune system from rejecting the transplanted islet cells. They will need to continue taking these drugs for life, which can result in complications.

Individuals who undergo a successful islet cell transplant may experience normal insulin production. This can allow people with type 1 diabetes to improve their glucose levels and potentially live without insulin treatment. However, people often require more than one transplant to achieve insulin independence.

While an islet cell transplant involves the transfer of cells from a donor pancreas, a pancreas transplant involves a person receiving a whole, healthy donor pancreas. Typically, the original pancreas will remain in the body, and the surgeon will connect the new pancreas to the intestines so that it can carry out its functions.

Often, people receiving a pancreas transplant will also receive a kidney, due to frequently coexisting kidney damage relating to type 1 diabetes. Evidence notes that roughly 80% of current pancreas transplants occur with a kidney transplant, and around 73% of people who receive this transplant become insulin independent after 5 years.

However, a pancreas transplant is a more invasive procedure, and as such, carries more risk and potential complications.

Research suggests that islet cell transplants may be a more promising option due to their lower surgical risk and lower toxicity from immunosuppressants, and may provide better glycemic control. However, more research is necessary to evaluate the long-term results for this option.

Islet cell transplantation can reduce or eliminate symptoms of type 1 diabetes. But this procedure comes with certain risks. Doctors only recommend the procedure when the benefits would outweigh the risks.

Typically, suitable candidates will include people living with type 1 diabetes who frequently experience severe hypoglycemic episodes, particularly if they also experience hypoglycemia unawareness. This is when people do not notice any symptoms of a hypoglycemic episode. This may include people who experience brittle diabetes.

Additionally, those planning to have a kidney transplant may also be suitable candidates. This is because a surgeon can perform the procedures at the same time, and a person receiving a kidney transplant will also require immunosuppressants. So the islet transplant will not add much more risk.

The procedure may not be suitable for individuals who:

  • require a lot of insulin
  • weigh over 85 kilograms
  • have poor kidney function
  • are planning a pregnancy
  • have other less common health issues

If people are suitable candidates, their doctors will usually place them on a waiting list for the transplant.

An islet cell transplant may help to improve the quality of life for those living with diabetes. It may alleviate the risk of severe hypoglycemia and improve glycemic control. The transplant may not only reduce the risk of experiencing diabetic complications, but a person will likely require fewer or no injections of insulin and may not need to strictly monitor their blood sugar levels.

These factors may also contribute towards relieving diabetes distress. This refers to the overwhelming stress a person may experience from managing the condition.

The potential benefits of islet cell transplantation may include:

  • improving quality of life
  • reducing the frequency of severe hypoglycemic episodes
  • reducing the risk of long-term complications of diabetes.
  • improving the awareness of hypoglycemic episodes

Because the islet cells come from a donor, there is a risk of rejection from the new host. Doctors prescribe immunosuppressants to reduce this risk. However, immunosuppressants also come with possible side effects, such as a higher risk for infections and certain cancers.

In addition to the potential risk of immunosuppressants, other risks of islet transplantation may include:

  • bleeding, blood clots, and pain after the procedure
  • the chance that the transplanted islets may not function correctly
  • development of antibodies against the donor cells, which makes it more difficult to find suitable donors for future transplants

Research from a 2016 clinical trial notes that 88% of people improved glycemic control and were free of severe hypoglycemic events a year after the first transplant. After 2 years, 71% of people still met these criteria. Other evidence suggests a 5-year insulin independence rate of 25–50%.

Most people who have an islet cell transplant experience positive effects on their type 1 diabetes symptoms. However, islet cell transplantation currently remains a rare procedure. More research is necessary to improve the surgery and determine the long-term impacts of this treatment.

In the U.S., experts still consider islet transplantation an experimental treatment. As a result, only hospitals with special permission from the Food and Drug Administration (FDA) can perform the surgery. From 1999–2015, the Collaborative Islet Transplantation Registry (CITR) reported that 1,086 people worldwide received an islet cell transplant for type 1 diabetes.

Additionally, it is difficult to acquire and process enough islet cells due to a shortage of organ donors. Until doctors can easily obtain sufficient amounts of islet cells, this will limit the number of possible transplants available.

Some researchers are investigating the potential of new approaches to creating artificial islet cells and stimulating adult stem cells to regenerate in a diabetic pancreas. But this is still in the early stages and more research is necessary.

Islet cell transplants can be useful for conditions other than type 1 diabetes. For example, individuals with chronic pancreatitis may also benefit from an islet transplant.

A treatment option for pancreatitis is a pancreatectomy, which is the removal of the entire pancreas. This can induce diabetes, as the individual can no longer naturally produce insulin. Therefore, a person may receive an autologous islet transplantation. This involves infusing a person’s own pancreatic islet cells into their liver to independently produce insulin.

Individuals living with type 1 diabetes may experience serious complications due to fluctuations in their blood sugar levels. People with diabetes that is difficult to control may benefit from an islet cell transplant. This procedure involves the transfer of insulin-producing islet cells from a donor pancreas into a new host. If successful, these cells can become active and may allow a person to become insulin independent.

While this experimental surgery is showing promise, it does come with risks. Additionally, it is not yet a common procedure due to a shortage of donors. More research is still necessary to refine this treatment option, but future research may help make the procedure more widely available for people with type 1 diabetes.