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 microm in diameter which were separated into five sub-populations based on their diameter. Next, a heterogeneous population of mouse pancreatic islets, between 50-250 microm 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 microm have superior stimulation indexes (SI) compared to islets larger than 150 microm. In this study, we found that islets between 100 microm and 150 microm in diameter had the greatest SI value in a heterogeneous population of islets.

A Microwell Cell Culture Platform for the Aggregation of Pancreatic β-Cells

“…As expected, the average aggregate diameter was less than the well width due to the penchant of b-cells to form clustered structures and the dominance of cell-cell interactions over cell material interactions. The range of aggregate sizes created via this method correlates well to that observed in naturally occurring murine islets, 41,42 thus providing a culture platform from which the effect of aggregate size on physiologically relevant properties could be investigated. While the model b-cell line used in this work did not show a size-dependent effect on cellular viability or functional expression, but rather demonstrated exceptional viability and function over all size aggregates, the effect of islet size on viability and function has been documented 41,43 suggesting that using this method to control islet reaggregation might be beneficial.…”

Effect of size on the cellular endocytosis and controlled release of mesoporous silica nanoparticles for intracellular delivery

“…The cellular uptake of liposome has also been found to be sizedependent (Chono et al 2007). Meanwhile, the size of the nanoparticles also had obvious effect on the drug loading and release profiles (Hu et al 2007;Kang et al 2008;Nam et al 2010). Hu (Hu et al 2007) reported that large particle size of PEG nanoparticles resulted in higher paclitaxel encapsulation efficiency and slower drug release rate.…”

Functional assessment of automatically sorted pancreatic islets using large particle flow cytometry

“…Recent publications show that mouse smaller islets perform better than larger islets when exposed to hypoxia followed syngeneic transplantation under the kidney capsule. 4,5,12 The smaller islet diameter implies a shorter diffusion distance and thereby a more effective supply of oxygen and nutrients. Evidence that the COPAS is not detrimental for islet function and viability opens the opportunity of applying this technology for the sorting of thousands of islets of homogeneous size within a few hours-a task that is unfeasible by manual sorting.…”

“…Accordingly, it has been reported that smaller islets display greater O 2 consumption and insulin secretion rates than larger islets. [4][5][6][7] The COPAS (Complex Object Parametric Analysis and Sorting) technology is based on traditional single cell…”