Effects of Cyclooxygenase-2 Inhibitor and Adenosine Triphosphate–Sensitive Potassium Channel Opener in Syngeneic Mouse Islet Transplantation

In the initial days after transplantation, islet grafts may be attacked by cytokines via cyclooxygenase-2 (COX-2), producing primary nonfunction. In addition, chronic overstimulation of β-cells may impair insulin secretion. To enhance the function of transplanted islets, the present study investigated the effects of rofecoxib, a COX-2 inhibitor, and NN414 (6-chloro-3-[1-methylcyclopropyl]amino-4H-thieno[3,2-e]-1,2,4-thiadiazine 1,1-dioxide), an adenosine triphosphate-sensitive potassium channel opener, on islet transplantation. Male inbred C57BL/6 mice were used as donors and recipients. One hundred fifty islets were isolated via collagenase digestion and density gradient, and syngeneically transplanted under the kidney capsule in mice with streptozotocin-induced diabetes. Recipients were treated with or without rofecoxib, 10 mg/kg/d orally, or with or without NN414, 3 mg/kg/d orally, for 4 weeks. After transplantation, recipient body weight, blood glucose concentration, and intraperitoneal glucose tolerance were measured. The grafted kidney was extracted for determination of insulin content at 4 weeks. In the rofecoxib-treated and NN414-treated groups and both control groups, body weight remained stable, and the blood glucose concentration decreased progressively. However, at 4 weeks after transplantation in the groups treated or not treated with rofecoxib or NN414, no significant difference was observed in recipient body weight, blood glucose concentration, and glucose tolerance or in insulin content of the graft. These data indicate that posttransplantation treatment with rofecoxib or NN414 has no beneficial effect on transplantation outcome in diabetic mouse recipients engrafted with a marginal islet mass.