From islet transplants to stem cell therapy for diabetes patients
Stem cells can be differentiated into insulin-producing cells.
Type 1 diabetes, a frequently occurring form of diabetes, can be cured with a transplantation of the pancreas or the islets of Langerhans. These transplants yield good results, but unfortunately very few donor pancreases are available. This is why Leiden researchers are developing a new method of treatment based on stem cells, allowing the treatment of multiple patients using a single donor’s pancreas.
When a person eats carbohydrates, the hormone insulin prevents the glucose level in his blood from rising too high. This hormone is produced by insulin-producing cells in the pancreas. Together, these cells are called the islets of Langerhans. In patients with type 1 diabetes, these islets have been destroyed by their own immune system, preventing them from producing insulin. This is why these patients are forced to take insulin injections. However, this does not protect them from the risk of developing serious secondary symptoms, such as kidney and heart failure.
Curing diabetes is currently possible either by transplanting the entire pancreas, which is a very invasive operation, or by transplanting the islets of Langerhans. These transplants yield very good results. After an islet transplantation, sixty to seventy per cent of patients treated no longer need insulin injections. With the remaining patients, the disease is much easier to control. Leiden University Medical Centre is the only Dutch medical centre where pancreas and islet transplants are performed. Each year around 20–25 patients are treated with a pancreas transplant and 5–6 patients receive an islet transplant. Professor Ton Rabelink explains: ‘A pancreas transplant is a difficult operation due to the digestive juices. It’s a very complex surgical procedure. It’s very difficult to remove the organ from the donor without the digestive juices leaking. This is why so few donor pancreases are available. Sometimes we are also offered pancreases that aren’t suitable for transplantation. Fortunately we can still use those to extract the islets of Langerhans for an islet transplant.’
New stem cell therapy
Recently, Rabelink and his colleagues have developed a new method with which they hope to be able to help many more diabetes patients. It is a treatment based on stem cells. The pancreas contains stem cells that can be differentiated into insulin-producing cells. When the islets are extracted from a donor pancreas for an islet transplant, Rabelink and his colleagues can also extract these stem cells. They have recently been able to show that these stem cells can be made to grow into insulin-producing cells in the lab. This means that they can probably be used for a transplant in the same way as extracted islets. Rabelink explains: ‘The advantage is that you can continue to cultivate these cells for a long time, allowing you to help multiple patients using a single donor pancreas.’ It may be that in the long term the same technology can be used to grow islets based on the patient’s own stem cells, obviating the patient’s need for medications to suppress the immune system. But that is still a long way off.