What are islets of Langerhans?
To begin with, pancreas is a spongy, small gland situated in the back of the abdomen and behind the stomach. The main function of pancreas is to make insulin, much required for controlling the blood sugar levels, and enzymes which help in digesting and metabolizing the food.
Islets of Langerhans, the insulin making tissue are a bunch of dedicated cells scattered in pancreas. These are further made of about five different types of cells including alpha cells which increase the level of glucose in blood and beta cells that make insulin. It is the degeneration or deterioration of these beta cells that causes Type 1 diabetes mellitus, an autoimmune disease.
It is to be re-iterated that insufficient manufacture and usage of insulin, can result in increased glucose levels in the blood. What happens in Type 1 diabetes is that since the body’s immune system attacks and destroys the beta cells of pancreas, they no longer make insulin. Thus a patient with Type 1 diabetes has to take the daily prescribed dose of insulin. Type 2 diabetes is recognized with a state of insulin resistance wherein the body cannot use the insulin successfully. Meanwhile, insulin production also reduces and thus the patients with Type 2 also need to take insulin ultimately.
Pancreatic islet transplantation
In this procedure of islet transplantation, healthy and functional islets of Langerhans are taken from the pancreas of a dead donor. These are then transplanted to the person in need wherein the beta cells in these islets once begin to manufacture or synthesize and release insulin.
Medical researchers anticipate that the islet transplantation will enable people with type 1 diabetes to lead a normal life once again without the administration of insulin. Over the past decade or so, experiments have shown that while a considerable percentage of patients stay free of the need to have insulin injections for a long time, others show reduced requirement of insulin and better glucose control. In many cases, however, the transplanted islets lose their capability to produce insulin again.
Using specific enzymes, the islets are taken out from the pancreas of a deceased donor. The transplantation has to be performed soon after the extraction because the islets are delicate. At times, the required number of islets are taken out from two donors and the patient undergoes two transplants sufficient enough to take them off the insulin administration.
These islets are transplanted or infused into the pancreas with the help of a catheter. The procedure can be performed under both local and general anesthesia. Though, soon after the transplantation, the islets begin to produce and release insulin, the complete functioning of islets is restored after some time and till then, the patient has to take insulin amidst regular checks for blood glucose levels.
Advantages of islet transplantation
If successful, the islet transplantation will result in efficient glucose control while eliminating the need of insulin administration. With good blood glucose level control comes other benefits like reduced risks of hypoglycemia, heart disease, kidney disease, and diabetic neuropathy or nerve damage and diabetic retinopathy or eye disease.
Risks associated with islet transplantation
Risks associated with islet transplantation include the possibility of bleeding, formation of blood clots and side effects of the immunosuppressant drugs which the recipients have to take lest their immune system rejects the islets transplanted into their pancreas recognizing it as a foreign body. In addition to this, there is a fear and a high possibility of the recipient’s auto-immune response attacking the transplanted islets, just the way it attacked the recipient’s own islets.
Side effects of these immuno suppressant drugs include decreased white blood cell counts, vulnerability to a host of other bacterial and viral infections, fatigue, anemia, hypertension, mouth sores, gastrointestinal disorders, elevated blood cholesterol levels and a reduced kidney function. An increased risk of cancer and tumours is yet another side effect of taking these immunosuppressive or anti-rejection drugs.
The shortage of islets from donors is a significant obstacle to widespread use of pancreatic islet allo-transplantation. Research is on for islet transplantation without the long term use of immunosuppressive drugs.