Simultaneous Monitoring of Insulin and Islet Amyloid Polypeptide Secretion from Islets of Langerhans on a Microfluidic Device

• Published in: Analytical chemistry (Washington) Vol. 85; no. 16; pp. 7919 - 7925
• Main Authors: Lomasney, Anna R, Yi, Lian, Roper, Michael G
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.08.2013
• Subjects: Animals; Channels; Dynamical systems; Dynamics; Glucose; Homeostasis; Hormones; Immunoassay; Insulin; Insulin - analysis; Islet Amyloid Polypeptide - analysis; Islets of Langerhans - chemistry; Limit of Detection; Male; Mice; Microfluidic Analytical Techniques - instrumentation; Peptides; Polypeptides; Secretions
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac401625g

A method was developed that allowed simultaneous monitoring of the acute secretory dynamics of insulin and islet amyloid polypeptide (IAPP) from islets of Langerhans using a microfluidic system with two-color detection. A flow-switching feature enabled changes in the perfusion media within 5 s, allowing rapid exchange of the glucose concentrations delivered to groups of islets. The perfusate was continuously sampled by electroosmotic flow and mixed online with Cy5-labeled insulin, fluorescein isothiocyanate (FITC)-labeled IAPP, anti-insulin, and anti-IAPP antibodies in an 8.15 cm mixing channel maintained at 37 °C. The immunoassay mixture was injected for 0.3 s onto a 1.5 cm separation channel at 11.75 s intervals and immunoassay reagents detected using 488 and 635 nm lasers with two independent photomultiplier tubes for detection of the FITC and Cy5 signal. RSD of the bound-to-free immunoassay ratios ranged from 2 to 7% with LODs of 20 nM for insulin and 1 nM for IAPP. Simultaneous secretion profiles of the two peptides were monitored from groups of 4–10 islets during multiple step changes in glucose concentration. Insulin and IAPP were secreted in an approximately 10:1 ratio and displayed similar responses to step changes from 3 to 11 or 20 mM glucose. The ability to monitor the secretory dynamics of multiple peptides from islets of Langerhans in a highly automated fashion is expected to be a useful tool for investigating hormonal regulation of glucose homeostasis.