Size-based separation and collection of mouse pancreatic islets for functional analysis

Abstract

Islet size has recently been demonstrated to be an important factor in determining human islet transplantation outcomes. In this study, a multi-layered microfluidic device was developed and quantified for size-based separation of a heterogeneous population of mouse islets. The device was fabricated using standard soft lithography and polydimethylsiloxane (PDMS). Size-based separation was first demonstrated via injection of a heterogeneous population of glass beads between 50–300 µm in diameter which were separated into five sub-populations based on their diameter. Next, a heterogeneous population of mouse pancreatic islets, between 50–250 µm in diameter was separated into four sub-populations. Throughout this process the islets remained intact without any signs of damage, as indicated by cell viability staining. Islet glucose-stimulated insulin secretion of each sub-population of islets was also evaluated demonstrating that islets smaller than 150 µm have superior stimulation indexes (SI) compared to islets larger than 150 µm. In this study, we found that islets between 100 µm and 150 µm in diameter had the greatest SI value in a heterogeneous population of islets.