|Islet cell transplantation|
Microscopic image of an islet of Langerhans (lighter area) surrounded by exocrine pancreas tissue (darker staining).
Islet transplantation is the transplantation of isolated islets from a donor pancreas and into another person. It is an experimental treatment for type 1 diabetes mellitus. Once transplanted, the islets begin to produce insulin, actively regulating the level of glucose in the blood.
Islets are usually infused into the patient's liver. If the cells are not from a genetically identical donor the patients body will recognize them as foreign and the immune system will begin to attack them as with any transplant rejection. To prevent this immunosuppressant drugs are used. Recent studies have shown that islet transplantation has progressed to the point that 58% of the patients in one study were insulin independent one year after the operation.
In the period from 1999 to 2004, 471 patients with type 1 diabetes have received islet transplants at 43 institutions worldwide.
The concept of islet transplantation is not new.File:Timeline CellR4 2013.jpeg Timeline of the progress in islet cell transplantation
 Investigators as early as the English surgeon Charles Pybus (1882–1975) attempted to graft pancreatic tissue to cure diabetes. Most, however, credit the recent era of islet transplantation research to Paul Lacy's studies dating back more than three decades. In 1967, Lacy's group described a novel collagenase-based method (later modified by Dr. Camillo Ricordi, then working with Dr. Lacy) to isolate islets, paving the way for future in vitro and in vivo islet experiments. Subsequent studies showed that transplanted islets could reverse diabetes in both rodents and non-human primates. In a summary of the 1977 Workshop on Pancreatic Islet Cell Transplantation in Diabetes, Lacy commented on the feasibility of “islet cell transplantation as a therapeutic approach [for] the possible prevention of the complications of diabetes in man”. Improvements in isolation techniques and immunosuppressive regimens ushered in the first human islet transplantation clinical trials in the mid-1980s. The first successful trial of human islet allotransplantation resulting in long-term reversal of diabetes was performed at the University of Pittsburgh in 1990. Yet despite continued procedural improvements, only about 10% of islet recipients in the late 1990s achieved euglycemia (normal blood glucose). In 2000, Dr. James Shapiro and colleagues published a report describing seven consecutive patients who achieved euglycemia following islet transplantation using a steroid-free protocol and large numbers of donor islets, since referred to as the Edmonton protocol. This protocol has been adapted by islet transplant centers around the world and has greatly increased islet transplant success.
The goal of islet transplantation is to infuse enough islets to control the blood glucose level removing the need for insulin injections. For an average-size person (70 kg), a typical transplant requires about one million islets, isolated from two donor pancreases. Because good control of blood glucose can slow or prevent the progression of complications associated with diabetes, such as nerve or eye damage, a successful transplant may reduce the risk of these complications. But a transplant recipient will need to take immunosuppressive drugs that stop the immune system from rejecting the transplanted islets.