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 -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 (r 2 =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.

Prediction of Clinical Outcome in Islet Allotransplantation

“…42) is a practical and complete method for the assessment of cell conditions. Alternatively, the mitochondrial oxygen consumption rate (OCR) has been proposed as a dynamic indicator of cellular viability (43)(44)(45). The central hypothesis is that the OCR of cells is directly proportional to viable tissue volume and that its normalization to DNA content is a measure of fractional viability.…”

Quantitative Assessment of Islets of Langerhans Encapsulated in Alginate

“…OCR, a direct measure of the rate of oxidative phosporylation in aerobic cells, has been suggested as a better measure of mitochondrial function than nucleotide concentrations 8,9 and has been measured with various systems. [34][35][36] We developed a stirred microchamber that permits rapid, accurate OCR measurements with a small volume of islet tissue. 37 This method was used in studies with human 38 and rat 39 islets transplanted into immunocompromised mice.…”

Correlating hypoxia with insulin secretion using a fluorescent hypoxia detection system

“…This implies that in terms of oxygenation, combined effects of capsule geometry and material may largely influence device success. However, beyond material and geometric considerations, a variety of factors such as islet size, 10,11 rate of oxygen consumption, 12,13 and site of implantation 14 all play a part in determining how much oxygen may be available to any particular cell. As such, a method for quickly detecting hypoxia in individual living cells would provide obvious benefits to the field of cell encapsulation.…”