Magnetic resonance imaging of intra-pancreatic ductal nanoparticle delivery to islet cells.

Background: The absence of reliable drug delivery systems to pancreatic islet cells hampers efficient treatment of type 1 diabetes. Nanoparticle delivery systems equipped with imaging capabilities could enable selective delivery to pancreatic islet cells. Biodistribution of nanoparticles is defined by several factors including the mode of administration, which determines accumulation in various organs.

Methods: In this study, we tested whether intrapancreatic ductal injection of magnetic nanoparticles would result in efficient cellular uptake by pancreatic islet cells. Dextran-coated iron oxide nanoparticles labeled with the near infrared fluorescent dye Cy5.5 were injected into the intrapancreatic ducts of streptozotocin-induced diabetic and healthy mice. To monitor the distribution of the nanoparticles, we performed in vivo magnetic resonance imaging followed by optical imaging and histology.

Results: Both imaging modalities demonstrated accumulation of the nanoparticles in the pancreas. However, histology revealed a high accumulation of nanoparticles in the insulin-producing cells in the pancreata of diabetic animals. By contrast, in nondiabetic controls, nanoparticles were mainly restricted to nonendocrine tissues.

Conclusions: Our results demonstrate that pancreatic ductal injection accompanied by image guidance could serve as an alternative pathway for nanoparticle delivery. We expect to utilize this intraductal delivery method for theranostic applications in type 1 diabetes.