Design of Islet-On-A-Chip Devices to Dynamically Measure Glucose-Stimulated Metabolism and Insulin Secretion in Individual Pancreatic Islets

Type 1 diabetes results from a loss of functional beta-cell mass due to autoimmune destruction. Currently, islet transplantation offers a treatment option but due to a limited supply of donor islets this treatment will never be universally available. Thus, engineering beta-cell tissue for transplantation would provide an opportunity to treat many more people. However, the success will depend heavily on tissue quality. To help inform in the design, we are creating a microfluidic device to simultaneously image multiple readouts of individual tissue function. First, we aim to measure c-peptide release as a proxy for endogenous insulin. This will be done by creating an on-chip competition assay based on c-peptide conjugated to 5-TAMRA (c-peptide∗) and changes in fluorescence anisotropy. Second, we are interested in measuring oxygen consumption rates of individual islets. Oxygen is a major contributor to the electron transport chain and can be used to identify perturbations in oxidative phosphorylation. We are using RuII(bpy)3 as an optical sensor to measure oxygen with excitation and emission maxima at 450nm, and 600nm, respectively. The oxygen sensitive dye will serve as a seed layer on the base of the device. Lastly, we are interested in measuring the extracellular acidification rate as a readout of glycolytic rate and/or oxidative phosphorylation. We will use HPTS, a pH sensitive dye, in solution. Each of these sensors are spectrally and/or spatially resolved. This strategy will allow us to simultaneously measure multiple responses in single islets. Overall, this multiparametric approach will allow us to better inform the production of engineered islets as well as screen the tissue prior to transplantation.