Islet Cell Transplantation: Can It Facilitate Insulin Independence?

By Jessica Kaylor, BA, and John S. Steinberg, DPM

Do islet cells hold promise in treating diabetes? Islet cells are groupings of hormone-secreting cells in the pancreas that are responsible for several endocrine functions including the production of insulin. Pancreatic islets contain four different types of cells including: insulin-producing beta cells, glucagon-releasing alpha cells, somatostatin-producing delta cells and cells that contain polypeptides (PP cells). Each individual islet contains approximately 1,000 of these four types of cells.

   In islet cell transplantation procedures, surgeons use enzymes to extract islet cells, typically from the pancreata of multiple deceased donors, in order to collect an ample amount of cells that can be immediately injected into the recipient’s liver. The surgeon would make an injection through the portal vein of the liver in order to facilitate easy access and maintain a minimal level of invasiveness. The cells remain in the liver, attach themselves to new blood vessels and begin to produce insulin from that location.1

   After a period of acclimation in the recipient’s system, the transplanted cells produce insulin and regulate the patient’s blood glucose level. As a result, the need for an insulin injection regimen or total pancreas transplant could be eliminated.2 This procedure has gained considerable attention in the medical community due to its extreme potential for benefit to people with diabetes. However, significant advancements are still necessary in order for islet cell treatment to become a comprehensive cure for diabetes mellitus type 1, in which insulin production is absent.

   Healthy glucose levels are crucial in decreasing the risk of common complications of diabetes mellitus. These complications include nerve, eye and limb degeneration, particularly of the foot. Typically, one attains euglycemia through a regimen of insulin injections, which are not ideal due to the pain involved and their relative inconvenience. Elimination of a shot regimen is of particular interest for juvenile patients who struggle with the considerable burden and responsibility involved in this glucose regulation method.

Weighing The Pros And Cons Of Islet Cell Transplantation

Islet cell transplantation, on the other hand, involves one surgical procedure usually performed with a local anesthetic, and can result in self-production of insulin by the recipient’s system for up to five years.3 The minimally invasive nature of this surgical option is preferred over the more elaborate procedure of total pancreatic transplantation. In addition to establishing possible insulin independence for a number of years, islet cell therapy may help control glycated HbA1c and decrease the recurrence of hypoglycemia.4

   Although current literature expresses optimism about the validity of islet cell transplantation as a solution for glycemic control, researchers are also realistic about the current limitations of this therapy. Significant advances are needed in order for this treatment course to become widely available and successful in establishing normaglycemia.

   The limited availability of donor islet cells and the rejection of these transplanted tissues by the recipient’s immune system are the two most serious challenges to islet cell transplantation. Approximately 1 million islet cells are needed for transplantation to be successful. As a result, two or more donors are usually needed per recipient, thus limiting the availability of ample transplantation material. The extraction process itself is relatively inefficient as well and contributes to the difficulty of obtaining islet cells for recipients.

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