Prevention of primary nonfunction of canine islet autografts by treatment with pravastatin

Nonspecific inflammation is the primary cause of early islet graft loss. We have shown in mice that pravastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, prevents primary nonfunction of islet isografts by reducing inflammatory reactions at the graft site. This study was designed to test the effectiveness of this agent in a large animal model, dogs, by transplanting autologous islets. After total pancreatectomy, islets were isolated by using a two-step digestion method, followed by discontinuous gradient centrifugation on EuroFicoll. A known number of freshly isolated islets were immediately transplanted back into the same dog via the portal vein. First, we determined the minimal islet number required to reverse diabetes by transplanting 3,000-10,000 IEQ/kg with no additional treatment. The number was found to be 4,000 IEQ/kg, and islets less than 4,000 IEQ/kg consistently failed. To test the effect of pravastatin, 3,000 IEQ/kg were transplanted into dogs that either received no further treatment or were treated daily with 20 mg/kg of pravastatin from days -2 to 14. Without pravastatin, this number of islets lowered blood glucose only transiently, and all four of these dogs became hyperglycemic within 1 week. In contrast, four of the five dogs treated with pravastatin became normoglycemic (