Basic and clinical science posters: Beta cells, islets and stem cells

Abstract

Aims: Exposure to high levels of glucose and iron have been co‐related to reactive oxygen species (ROS) generation and oxidative stress in beta cell. This study aimed to test their accumulation in the beta cell and effects upon cellular oxidative dysfunction, cell viability, and insulin synthesis and secretion. Methods: MIN6 pseudoislets were exposed to a range of iron concentrations (20–100µM) at predefined glucose levels (5.5 and 11mM) in a static incubation experiment (48 and 72h). Iron storage was assessed by a ferritin immunoassay. Cellular insulin release and content were measured by an insulin immunoassay. ROS mediated cellular oxidative stress was estimated by measuring cellular lipid peroxidation (TBARS assay) and cell viability was assessed by a resazurin dye‐based assay. Results: Our results demonstrate that the presence of 11mM glucose and 100µM iron exposure at 72h exerted the most detrimental effect on the MIN6 beta cell viability (viability ≤59.5% and ≤54% respectively, n = 4). This observation is consistent with the data from cellular iron uptake analysis, which revealed the highest iron accumulation (ferritin = 325 ± 2.62ng/µg protein, n = 4) and TBARS assay that demonstrated the highest levels of lipid peroxidation (323.9 ± 1.57nmol/µg protein, n = 4) under these conditions. Insulin secretion and content were progressively decreased corresponding to chronic incubation time (27.5 ± 0.4and 38.4 ± 2.83ng/mg protein, respectively, p < 0.05, n = 4). Summary: Our data suggest that exposure to high iron and glucose concentrations results in cellular damage and may initiate secretory dysfunction in the beta cell.