The Transplantation of Pancreatic Islets to Portal Vein: The Influence on Liver Tissue

Pancreatic islet (PI) transplantation (Tx) to the portal vein is an established therapeutic modality for selected type 1 diabetic patients. However, a comprehensive review considering the effects of PIs on surrounding liver tissue is lacking. Typical interactions can be detected in the early and delayed phases. This review summarizes known side effects of PI transplantation. In early phase the interaction occurs immediately upon contact of the PI into portal vein blood. Mechanical obstruction, exacerbated by thrombosis as part of the instant blood-mediated inflammatory reaction (IBMIR), leads to ischemic injury to adjacent liver tissue. Delayed changes, such as focal steatosis and glycogen accumulation appear days to weeks after Tx and are caused by local overstimulation of hepatocytes by insulin in supraphysiological concentrations. In animal models these lesions could progress over months to cystic cholangiomas or hepatocellular carcinomas. Such neoplastic changes have been observed in experimental animals; they have not been reported in human patients. In conclusion, while PITx into the liver is not an optimal procedure, it currently represents the site offering the best functional integration of the graft. The adverse effects discussed are pronounced but generally not severe, nor do they appear to compromise the overall health status of the recipients.