Positron-emission tomography imaging of early events after transplantation of islets of Langerhans

The aim of our study was to assess cell trafficking and early events after intraportal islet transplantation. Sprague-Dawley rat islets were incubated for various times, with various concentrations of 2-[F-18]fluoro-2deoxy-D-glucose (FDG), and in presence of various glucose concentrations. FDG-labeled syngeneic islets or FDG alone were injected in rats. Radioactivity was measured in the liver and in various organs by positron-emission tomography for 6 hours. FDG uptake increased with incubation time or FDG concentration and decreased in presence of glucose. In vivo, all islets implanted in the liver, with an uptake 4.4 times higher than controls (44.2% vs. 10.1%, P=0.02). Radioactivity in the liver decreased at the same rate after injection of labeled-islets and FDG alone. Ex vivo labeling of islets and imaging of posttransplant early events were feasible. Islets engrafted exclusively in the liver. No islet loss could be demonstrated 6 hours after transplantation.