Parallel multi-parametric monitoring of single pancreatic islets in a microfluidic Organ-on-Chip system made from glass

Background and aims Obtaining reproducible and reliable data from small amounts of tissue is still a major problem in basic and preclinical research on pancreatic islets. Here, we demonstrate an islet-on-chip system made from glass for parallel multi-parametric measurements of single pancreatic islets to overcome this challenge.

Materials and Methods The chip was made from glass by femtosecond laser ablation and subsequent surface smoothing. The flow dynamics were characterized by simulation and by measuring washout-kinetics of fluorescent dyes. NAD(P)H-, FAD- autofluorescence and Cal 630 fluorescence (cytosolic Ca2+ concentration=[Ca2+]i) of NMRI mouse islets were simultaneously measured in five independent experiments by live cell imaging. Insulin content of fractionated efflux was measured by ultrasensitive ELISA.

Results The islet-on-chip system had the size of a microscope slide and contained five independent parallel channels, each with a well of 500 µm depth to hold a single islet. An aperture above the well permitted loading and unloading of the islet. Fluorescence washout-kinetics confirmed the uniformity of channels and wells. Islets were well retained at perfusion velocities of 40 µl / min and responded to 25 mM glucose with increased insulin secretion, increased levels of NAD(P)H and FADH2 and an oscillatory pattern of [Ca2+]i. 40 mM KCl markedly increased insulin secretion and [Ca2+]i, but caused only a minor increase of NAD(P)H and FADH2.

Conclusion The present microfluidic islet-on-chip system with a parallel independent channel design permits robust multi-parametric characterization of individual islet function. Thus, throughput, precision and coherence are increased as compared to conventional perifusion systems.

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Artikel online veröffentlicht:
06. Mai 2021