Increased oxygen consumption rates in response to high glucose detected by a novel oxygen biosensor system in non-human primate and human islets

Abstract

In this study, we investigated the use of a novel oxygen biosensor system to detect changes in oxygen consumption rates (OCRs) by islets in response to glucose. Islets from non-human primate and human pancreata were seeded into an oxygen biosensor system microplate and exposed to basal (2.8 or 5.6 mM) or high (16.7 or 33.3 mM) glucose over either a long-term or a short-term culture. Our data clearly demonstrated that non-human primate islets cultured in high glucose conditions exhibited significant increases in OCRs over a 168 h extended culture period (P<0.05), which indicates an accelerated rate of β-cell metabolism triggered by glucose over time. Significant increases in OCRs (P<0.01) were also attained in both non-human primate and human islets exposed to high glucose conditions in a 120 min short-term incubation period. OCRs exhibited by human islets exposed to different glucose concentrations correlated with insulin secretion (r2=0.7681, P<0.01). Moreover, the OCR stimulation index (i.e. OCR at high glucose/OCR at basal glucose) was significantly greater in human islets displaying high viabilities as opposed to islets exhibiting low viabilities (P<0.05). Together these data demonstrate that this novel oxygen biosensor system documents significant increases in islet oxygen consumption upon acute and chronic exposure to high glucose concentrations. Importantly, this methodology rapidly and robustly detects changes in OCRs by islets in response to high glucose stimulation that correlate well with the metabolic activities and functional viability of islets and clearly delineates significant differences in OCR stimulation index between high and low viability human islets, and therefore may prove to be an effective approach for quickly assessing the functional viability of islets prior to transplantation.