Redox Modulation Protects Islets From Transplant-Related Injury

Abstract

OBJECTIVE Because of reduced antioxidant defenses, β-cells are especially vulnerable to free radical and inflammatory damage. Commonly used antirejection drugs are excellent at inhibiting the adaptive immune response; however, most are harmful to islets and do not protect well from reactive oxygen species and inflammation resulting from islet isolation and ischemia-reperfusion injury. The aim of this study was to determine whether redox modulation, using the catalytic antioxidant (CA), FBC-007, can improve in vivo islet function post-transplant. RESEARCH DESIGN AND METHODS The abilities of redox modulation to preserve islet function were analyzed using three models of ischemia-reperfusion injury: 1) streptozotocin (STZ) treatment of human islets, 2) STZ-induced murine model of diabetes, and 3) models of syngeneic, allogeneic, and xenogeneic transplantation. RESULTS Incubating human islets with catalytic antioxidant during STZ treatment protects from STZ-induced islet damage, and systemic delivery of catalytic antioxidant ablates STZ-induced diabetes in mice. Islets treated with catalytic antioxidant before syngeneic, suboptimal syngeneic, or xenogeneic transplant exhibited superior function compared with untreated controls. Diabetic murine recipients of catalytic antioxidant–treated allogeneic islets exhibited improved glycemic control post-transplant and demonstrated a delay in allograft rejection. Treating recipients systemically with catalytic antioxidant further extended the delay in allograft rejection. CONCLUSIONS Pretreating donor islets with catalytic antioxidant protects from antigen-independent ischemia-reperfusion injury in multiple transplant settings. Treating systemically with catalytic antioxidant protects islets from antigen-independent ischemia-reperfusion injury and hinders the antigen-dependent alloimmune response. These results suggest that the addition of a redox modulation strategy would be a beneficial clinical approach for islet preservation in syngeneic, allogeneic, and xenogeneic transplantation.