PANCREAS AND ISLET TRANSPLANT
The concept of pancreatic transplant, in fact, preceded the discovery of insulin. In 1890, Von Mering and Minkowski reported that the removal of pancreas produced diabetes. In 1892, Minkowski and Hedon transplanted portions of whole pancreas to reverse diabetes in animals. In 1894, Williams transplanted sheep pancreas into a child with diabetes. This transplant failed and the boy died three days later.
The first transplant of human pancreas was performed by Kelly in 1966. The major part of the pancreas produces powerful digestive enzymes. The islet cells, scattered throughout the pancreas produce insulin. The digestive enzymes of the pancreas can damage the site of the transplant and the transplant itself. The other problem that arises is that the recipient's body rejects the pancreas as "foreign". Powerful drugs are required to suppress this normal rejection phenomenon.
"Until recently, despite substantial improvements in quality of life reported by many pancreas transplant recipients, the perception persisted that pancreas transplantation was an experimental procedure. However, significant advances have been made and pancreas transplantation is the only treatment for type 1 diabetes that can induce insulin-independent normoglycemia. Currently, pancreas transplantation is considered a therapeutic option for patients with all stages of diabetes, even those with advanced extra pancreatic complications. More than 15,000 pancreas transplants were reported to the International Pancreas Transplant Registry (1PTR) between 1966 and October 3,2000; 11,000 of those procedures were performed in the United States. Simultaneous pancreas-kidney (SPK) transplantation is by far the most common approach, accounting for 86% of cases performed in the United States between 1994 and 2000. Pancreas transplantaion alone (PTA) accounted for 4% of cases, while pancreas after kidney (PAK) transplantation accounted for the remaining 10%. Refined surgical techniques and better immunosuppressive drug regimens have significantly improved patient and graft survival rates for all pancreas transplant procedures. Data from the 2000 IPTR Annual Report documented a 1-year patient survival rate of 95% in SPK recipients; kidney and pancreas graft survival rates were 92% and 82%, respectively, between 1998 and 2000. One-year patient and graft survival rates of 100% and 76%, respectively, for the PTA transplantation were recorded during this same time period, while 1 -year patient and graft survival rates were 94% and 74%, respectively, following PAK transplantation.
Pancreas transplantation restores euglycemia, slows the progression of end-organ complications, and improves quality of life in patients with insulin-dependent diabetes. Because pancreas transplantation is not without risks, it is generally indicated in patients with complications of type 1 diabetes more serious than the risk of transplant surgery and chronic immunosuppression. There is also a subgroup of patients with type 2 diabetes (typically 30-40 years of age) who become insulin-dependent several months after the introduction of oral antihyperglycemic agents and develop secondary complications of diabetes 10-20 years later. This group of patients may in fact have type 1 diabetes and, therefore, benefit from pancreas transplantation
Pancreas transplantation can be performed via a number of surgical techniques and approaches. The whole pancreas or a segment of the pancreas can be transplanted.
Future clinical studies will continue to focus on appropriate recipient selection, minimally invasive surgical techniques, immunologic monitoring, immunosuppressive reduction, and outcomes-based research. Recently, the concept of "bioartificial pancreas" is being studied. Conceptually, this islet-surrogate model would consist of encapsulated islet cells that are protected from immune attack by a selectively permeable membrane barrier, and capable of releasing molecules of interest such as insulin into the bloodstream in response to metabolic stimuli. Ideally, such a closed-loop system would obviate the need for exogenous insulin and could be of significant benefits for islet transplantation.