Development and characterization of simulant pancreatic islets

Insulin is stored in pancreatic islets as a zinc-insulin complex, and stimulating the islets results in the release of insulin and zinc. Simulant pancreatic islet beads have been developed using agarose beads (50-250 micro m diameter) derivatized with iminodiacetic acid that have been loaded with zinc. A qualitative comparison of the simulant beads with pancreatic islets has been made by staining with dithizone and a zinc-binding fluorescent dye, TSQ. The binding capacity of simulant beads was determined to be 34 micro mol Zn(2+)/g of dried beads using anodic stripping voltammetry. Hydrochloric acid was used to release zinc from beads to mimic the secretion of insulin from pancreatic islets and a release profile was established. The simulant beads can be used to optimize the islet isolation process and reduce the use of real islets in method development.