Low-temperature preservation of isolated islets is superior to conventional islet culture before islet transplantation.

BACKGROUND: Although culturing islets before transplantation provides flexibility for evaluation of isolated islets and pretreatment of patients, it is well-known that isolated islets deteriorate rapidly in culture. In this study, we evaluated optimal temperature for culture/preservation of isolated human islets before transplantation.
METHODS: Isolated islets were cultured or preserved for 48 hr in the following culture/preservation conditions: preservation at 4 degrees C in University of Wisconsin solution and culture at 22 degrees C or 37 degrees C in culture medium.
RESULTS: Islet morphology after 4 degrees C preservation was similar to that of fresh islets, whereas islet diameter after 37 degrees C or 22 degrees C culture was smaller than that of fresh islets. Islet yield significantly decreased at higher temperatures (24% loss in 37 degrees C culture and 19% loss in 22 degrees C culture, but <5% loss in 4 degrees C preservation). Cultured/preserved islets were transplanted into diabetic nude mice. The attainability of posttransplantation normoglycemia was significantly higher in the 4 degrees C preservation group than in 22 degrees C and 37 degrees C culture groups.
CONCLUSION: Preservation of isolated islets at 4 degrees C improves the outcome of islet transplantation more efficiently than preservation at 22 degrees C or 37 degrees C. Based on these data, we have performed short-time cold storage of isolated islets instead of culturing for current clinical islet transplantation.