Limitations of Islet Transplantation: Engraftment and Long-Term Function

A typical adult pancreas contains approximately one million islets, which represent around 1–2% of the total mass of the organ. It has been estimated that only 50% will survive the harsh process of isolation, with up to 60–80% of the remaining mass perishing in the immediate posttransplantation period due to inflammatory processes not yet fully understood. For instance, it has been shown that islets express tissue factor which may contribute to early islet loss by stimulating coagulation upon their contact with the blood. Considering the many insults that may invariably result in islet cell death from the time of the pancreas procurement to the actual infusion, the fact that only 10% of the transplanted patients are insulin-free 5 years after the procedure is much less surprising than the observation that up to 80% are insulinfree after 1 year. While we define alternative sources of islets that are either plentiful (xenotransplantation) or self-renewable (stem cells), there is an imperative need to “make every islet count” and to minimize their destruction upon implantation. The field of islet cytoprotection is a fertile one, with a large number of chemical gene-based, and protein transduction strategies proven successful in many experimental models. However, it is still necessary to gather much more information Read the rest of this entry »