Some of the most fascinating work which has been going on for the past decade or so deals with islet cell transplants. Researchers believe that this therapy has the potential to CURE diabetes in people with Type I diabetes and will do away with the need for insulin injections in those with Type II diabetes. This, in itself will be a major advance as any person who takes daily insulin injections will tell you !
The islets of Langerhans are clusters of cells present in the pancreas. One of the types of cells in these clusters are the "beta" cells which produce insulin. When these cells are destroyed, the body cannot make any insulin and the person develops Type I diabetes or what was once called insulin dependent diabetes. Type I diabetics cannot survive unless they inject themselves with insulin every day. In India, people with Type I diabetes are a small minority. They make up around 1-2% of all those with diabetes. But when one is talking of 25-30 million people with diabetes in India, the numbers are huge!
The rest of the people with diabetes have what is called Type II diabetes. This was previously called non insulin dependent diabetes. This was unfortunate as it made people feel that they would never need insulin as a form of treatment. This is far from true.
Sooner or later, most people with diabetes will require insulin injections. Nobody likes to take injections and that too daily and often more than once a day. This is why the concept of islet transplants opens up fascinating vistas. Why inject insulin daily? Why not transplant the very cells which make insulin into the body! After all when the kidneys fail, do we not do a kidney transplant? The idea is at the same time so simple, so basic and yet so fantastic! You have insulin requiring diabetes? The deficit in the amount of insulin you can secrete can be made up by the transplanted cells. Why take daily injections of insulin? Your beta cells have failed after so many years? Transplant cells which are still active. Why take daily insulin injections? You have Type I diabetes and cannot secrete any insulin. Let the transplanted cells secrete the insulin you need. Why take daily insulin injections? In fact, if you have Type I diabetes, you would be CURED!
At present, islet transplantation is still experimental therapy, although it has been tried with varied results in some specialised centers. Scientists have made significant progress especially in last decade, but there are still some barriers to be overcome. Two major obstacles are the means of obtaining a sufficient number of cells to transplant, and more importantly, how to prevent the body from "rejecting" the transplanted cells.
Early findings show that about 1 million islet cells have to be transplanted to make enough insulin so that insulin injections will no longer be necessary, especially for people with Type I diabetes. The number of people who could benefit from transplants is larger than the number of human organ donors available each year, so researchers around the world are studying the use of islet cells from human fetal tissue or other species such as pigs and new born rabbits. The use of these tissues has done away with the fear that we would not have enough islet cells to transplant.
Rejection is the biggest problem with any transplant. The immune system is programmed to destroy "foreign" invaders such as bacteria and viruses. However, the system also destroys "invited foreigners," such as transplanted islet cells. Large doses of medicines, called immuno suppressants, are necessary to stop the immune system from rejecting the transplant. For most people, the side effects and risks of immuno suppressants are greater than the benefits of transplantation.Researchers are trying to develop methods of transplanting islet cells to reduce or eliminate the need for immuno suppression and the risk of rejection. One such method is called immuno isolation. As its name implies, this method tries to separate the islets from the immune system of the patient by coating cells or encapsulating them into microscopic containers. The plasma can come into contact with the transplanted cells and these will secrete insulin into the system, But the coating or the encapsulating material will not allow the lymphocytes and other cells (which are central to the immune rejection) are not allowed to come into contact with the transplanted cells and therefore these cells may escape rejection.
As its name implies, tries and alters the transplanted cells in such a manner that whilst they retain the capacity to secrete insulin, their surface is changed so that the immune system does not notice or attack them.
A Chinese proverb says," A journey of a million miles starts with one small step". Although we have walked many a step in the quest for perfecting islet transplants, there are many steps still to go. But there is more than a glimmer of light at the end of the tunnel. Freedom from insulin injections and a cure for diabetes may not be too distant.