Glucose-Stimulated Increment in Oxygen Consumption Rate as a Standardized Test of Human Islet Quality

Abstract

Standardized assessment of islet quality is imperative for clinical islet transplantation. We have previously shown that the increment in oxygen consumption rate stimulated by glucose (∆OCR glc ) can predict in vivo efficacy of islet transplantation in mice. To further evaluate the approach, we studied three factors: islet specificity, islet composition and agreement between results obtained by different groups. Equivalent perifusion systems were set up at the City of Hope and the University of Washington and the values of ∆OCR glc obtained at both institutions were compared. Islet specificity was determined by comparing ∆OCR glc in islet and nonislet tissue. The ∆OCR glc ranged from 0.01 to 0.19 nmol/min/100 islets (n = 14), a wide range in islet quality, but the values obtained by the two centers were similar. The contribution from nonislet impurities was negligible (∆OCR glc was 0.12 nmol/min/100 islets vs. 0.007 nmol/min/100 nonislet clusters). The ∆OCR glc was statistically independent of percent beta cells, demonstrating that ∆OCR glc is governed more by islet quality than by islet composition. The ∆OCR glc , but not the absolute level of OCR, was predictive of reversal of hyperglycemia in diabetic mice. These demonstrations lay the foundation for testing ∆OCR glc as a measurement of islet quality for human islet transplantation.

Surface-Enhanced Raman Spectroscopy-Based Label-Free Insulin Detection at Physiological Concentrations for Analysis of Islet Performance

“…Secretions from the islets were collected using a flow-culture system under low glucose (3 mM) and high glucose (17 mM) environments as discussed in the experimental section (Supporting information file). 8 We established the insulin concentrations of the collected 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 9 secretion samples by performing the ELISA on an aliquot extracted from each secretion sample.We applied the collected secretion samples to 3D Au-NP cluster chips and measured SERS signals (Figure 3). Difference in the SERS intensity from low-glucose and high-glucose secretions was clearly visible.…”

“…Before transplantation these islets are screened for their viability and functional response to changing glucose concentration in order to reduce the chances of transplant failure. [7][8][9] Sensors capable of detecting secretion of insulin from beta cells in a costeffective, label-free manner with minimal stress to the cells can serve vital roles in clinical quality assessment of islets. External monitoring of insulin concentration can also help in disease diagnosis and management as well as prevent potentially fatal insulin overdoses or hypoglycemia in diabetic patients.…”

Human islet preparations distributed for research exhibit a variety of insulin-secretory profiles

“…Furthermore, how or whether to assess the health and function of health of islet preparations prior to study is not standardized. Some laboratories assess human islet health and/or function using methods such as measurement of oxygen consumption (7,35) or insulin release in response to stimuli (3,10), among others (15,16). Although studies have examined the relationship between donor attributes and insulin release in the context of a single isolation center (9), little is known about insulin secretion compared among islet preparations from different isolation centers, which reflects how human islet research is currently being conducted in most research laboratories.…”

Correlation of Released HMGB1 Levels with the Degree of Islet Damage in Mice and Humans and with the Outcomes of Islet Transplantation in Mice

“…Recently, tests for cellular composition and β-cell via-(Mediatech, Inc., Manassas, VA), respectively, at 37°C in 95% air and 5% CO 2 for 24 h after islet isolation. In bility (7), mitochondrial membrane potential (5,16), and oxygen consumption rate of islets (19,30,31,33) were the mouse model, islets were divided into four groups: control, hypoxia-3h, hypoxia-6h, and hypoxia-24h islets. developed and proved their reliability for predicting in vivo transplant results.…”