Secretion of insulin by pancreatic islets is crucial for glucose homeostasis; disorders in islet function contribute to all types of diabetes mellitus. Transplantation of pancreatic islets into the liver is an emerging therapy for type 1 diabetes. However, limitations in assessing the number or mass of islets in vivo greatly hinder efforts to understand islet physiology and pathophysiology and to develop new therapies. Pancreatic islet size (50-200 μM), location (scattered throughout pancreas or liver after transplantation), and mass (only 1-2% of pancreatic mass and < 1% of liver mass after transplanted into the liver) create formidable challenges to non-invasively assess islet mass. One molecular imaging modality being adapted to non-invasively assess islet mass is in vivo bioluminescence imaging (BLI). BLI refers to the quantification of photons emitted from luciferase-expressing cells after luciferin administration using a sensitive chargecoupled device. This review summarizes approaches to use BLI to non-invasively assess murine and human islets after transplantation into immunodeficient mice. The ability to sequentially assess islet mass in vivo should allow investigators to investigate the events after islet transplantation and to develop interventions to improve islet survival.
Keywords: luminescence, pancreatic islets, transplantation, insulin, imaging, diabetes