Development and Application of Analytical Techniques for Evaluating Function in Pancreatic Islets of Langerhans.

Type 1 diabetes is caused by autoimmune destruction of insulin-secreting beta-cells found in the islets of Langerhans of the pancreas. Severe cases can be treated in a minimally invasive way by islet transplantation; however, islet transplantation has been limited by an inability to measure islet viability and potency prior to transplant. To address this need, we have developed a microfluidic platform to measure both intracellular calcium flux and insulin secretion, two important indicators of beta-cell function, at high temporal resolution during glucose treatment. Combining these measures on islets required methods for measuring fluorescence at two separate locations on a microfluidic system. To accomplish this objective, we used a 2-chip system in which perfusate was collected in fractions while intracellular calcium was measured using fluorescence imaging. The perfusate was subsequently analyzed for insulin by microchip electrophoresis with laser-induced fluorescence detection (MCE-LIF) using the same fluorescence microscope. We were able to distinguish first and second phase insulin secretion from batches of 8-10 islets with 80 s temporal resolution. Measured basal and peak first phase insulin secretion correlated well with previously reported results. Total analysis time using this system was