sea-0400 and Diabetes-Mellitus--Type-1

Pancreatic islet transplantation is an attractive therapy for the treatment of insulin-dependent diabetes mellitus. However, the low efficiency of this procedure necessitating sequential transplantations of islets with the use of 2-3 donors for a single recipient, mainly due to the early loss of transplanted islets, hampers its clinical application. Previously, we have shown in mice that a large amount of HMGB1 is released from islets soon after their transplantation and that this triggers innate immune rejection with activation of DC, NKT cells and neutrophils to produce IFN-γ, ultimately leading to the early loss of transplanted islets. Thus, HMGB1 release plays an initial pivotal role in this process; however, its mechanism remains unclear. Here we demonstrate that release of HMGB1 from transplanted islets is due to hypoxic damage resulting from Ca(2+) influx into β cells through the Na(+) /Ca(2+) exchanger (NCX). Moreover, the hypoxia-induced β cell damage was prevented by pretreatment with an NCX-specific inhibitor prior to transplantation, resulting in protection and long-term survival of transplanted mouse and human islets when grafted into mice. These findings suggest a novel strategy with potentially great impact to improve the efficiency of islet transplantation in clinical settings by targeting donor islets rather than recipients.

Topics: Aniline Compounds; Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Flow Cytometry; Graft Rejection; HMGB1 Protein; Humans; Hypoxia; Islets of Langerhans; Islets of Langerhans Transplantation; Male; Mice; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, SCID; Phenyl Ethers; Sodium-Calcium Exchanger