A Novel Microfluidic-Based Array For High-Resolution High-Content Imaging of Islets Before Transplant.

Abstract

Background: In order to facilitate in vitro study of pancreatic islets before the transplant, a microfluidic chip was designed to trap individual islet in an array format which allows us to study physiology and pathophysiology of islets in high-resolution fashion for high-content imaging. METHODS: (1) A microfluidic array was designed based on hydrodynamic principle for pressure drop in a micro channel. (2) Fluid flow simulation performed using COMSOL to verify design principle and minimal shear stress on islet cells. (3) A thin PDMS membrane was integrated as an oxygen controller. RESULTS: (1) Flow simulation verified the design principle, showing maximum velocity in trapping sites with minimum shear stress. (2) The device is capable of trapping up to 200 islets individually in an array format with 99% efficiency. (3)Both loading/trapping islets and fluid flow control were performed using gravity based flow control which eliminated the need for pumps. (4) The oxygen controller can provide fast oxygen microenvironment (less than 30 s) and varying and consistent oxygen concentrations and profiles. (5) As a result of having one layer design and using a very thin glass substrate,the device allowed multiparametric fluorescent and confocal imaging of islet cellular and subcellular metabolic activity and ion signaling such as mitochondrial energetics, ROS levels, calcium influx, and redox activity for high resolution high-content imaging purposes. CONCLUSION: We designed, fabricated, and validated a novel microfluidic platform that allows trapping individual islets with high efficiency. Device also allowed for co-culturing islets and hypoxia studies, showing an improvement over conventional hypoxia chambers. The device allowed high-resolution imaging of islet using fluorescence and confocal microscopy and high-content multiparametric imaging of key insulin stimulator-secretion coupling factors. This work demonstrates the feasibility of array-based cellomics analysis.