Pancreatic islet transplantation: is purification necessary?

Abstract

Successful islet allotransplantation in diabetic patients has been slow to develop. In the past, it has been assumed that the low success rates are, in part, due to difficulty in obtaining high-quality human islet preparations. The assumption has been that purified islets are essential because exocrine contamination hampers engraftment and makes islets more vulnerable to rejection by increasing graft immunogenicity. We reviewed the existing experimental data on the consequences of exocrine contamination and concluded that most clinical trials of islet allotransplantation have involved efforts to over-purify the allograft. Until antigen-specific tolerance or the biohybrid artificial pancreas is a reality, the best strategy for clinical trials is to test new immunosuppressive protocols in a search for a more effective way of modifying the host's immune response while maximizing islet yield by using less pure preparations.