Pancreas preservation in extracellular-type p38 inhibitor-containing solution improves islet yield for porcine islet isolation

Background: For islet transplantation, pancreas preservation and islet isolation activate p38, which is a member of the stress-activated group of mitogen-activated protein kinases (MAPKs). In this study, we evaluated an extracellular-type p38 inhibitor-containing (EP) solution with University of Wisconsin (UW) solution, the gold standard for organ preservation. The EP solution has high sodium-low potassium composition with low viscosity compared to UW solution. Moreover, EP solution contains a recently developed p38 inhibitor (11R-p38I₁₁₀) from our laboratory. Methods: Porcine pancreata were preserved in UW, EP, or EP-P solution (EP solution without 11R-p38I₁₁₀), and then islet isolation was performed. An optimized number (1500 IE) of isolated islets from each group were transplanted into streptozotocin-induced diabetic mice. Results: The islet yield before and after purification was significantly higher in the EP group than in the UW group. The islet yield before and after purification was not significantly different between the EP and EP-P groups; however, the EP solution prevented a reduction in the number of islets during culture. Western blot analysis showed that p38 activation was attenuated by EP solution. For islet transplantation into streptozotocin-induced diabetic mice, pancreas preservation in EP solution improved the outcome of islet transplantation. Conclusions: Pancreas preservation with EP solution preserved islet function better than with UW solution. The advantages of EP solution over UW solution may include the inhibition of p38 activity as well as the composition of the solution.