A Novel Preservation Solution Containing a JNK Inhibitory Peptide Efficiently Improves Islet Yield for Porcine Islet Isolation

Background. For islet transplantation, pancreas preservation in University of Wisconsin (UW) solution is associated with disadvantages, such as collagenase inhibition, resulting in poor islet yield and islets with poor viability. In this study, we evaluated a novel preservation solution, the extracellular-type c-Jun N-terminal kinase (JNK) inhibitor-containing (EJ) solution. Methods. The EJ solution has high sodium-low potassium composition with low viscosity compared to UW solution. Moreover, EJ solution contains a recently developed JNK inhibitor from our laboratory. Results. We first compared the performance of EJ solution with that of UWsolution. Islet yield before and after purification was significantly higher in the EJ group than in the UWgroup. Second, we compared the performance of EJ solution with that of EJ solution without the JNK inhibitor (EJ-J solution). After pancreas preservation in EJ solution, JNK activity was maintained at a relatively low level during islet isolation. Islet yield before and after purification was significantly higher in the EJ group than in the EJ-J group. After islet transplantation into streptozotocin-induced diabetic mice, blood glucose levels reached the normoglycemic range in 61.5% and 7.7% of diabetic mice in the EJ and EJ-J groups, respectively. Moreover, EJ solution exhibited reduced inhibition of collagenase digestion compared with UW solution. Conclusions. Advantages of EJ solution over UW solution were inhibition of JNK activity and reduced collagenase inhibition. EJ solution may therefore be more suitable for islet isolation than UW solution.