Design Of A Multiparameter Islet-On-A-Chip Device To Measure The Functional Variability Of Individual Pancreatic Islets

Type 1 diabetes results from autoimmune destruction of pancreatic islets, small micro-tissues (∼150 μm) that are primarily composed of insulin secreting beta-cells. Islet transplantation is a current treatment option, but will never be universally available due to limited supply of donor tissue. Tissue engineered islets could help bridge this gap and provide an opportunity to treat many more people. However, the success will depend heavily on the quality and uniformity of the engineered tissue. To inform in the design, we are creating a microfluidic device to assay multiple readouts of function on individual islets and engineered micro-tissues. 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 aim to measure oxygen consumption rates of individual islets. Oxygen is consumed by 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 450 and 600 nm, respectively. Lastly, we aim to measure 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 is spectrally and/or spatially resolved from one another. This strategy will allow us to simultaneously measure these responses to fully index the function of individual islets and engineered micro-tissues. This multiparametric characterization could inform the production of engineered islets as well as assist in the screening of tissue prior to transplantation.