Development and characterization of a novel microfluidic chip for exosome isolation and its application in neuroscience

Abstract

Exosomes are membrane bound extracellular vesicles formed from multivesicular bodies ranging in size from 50 to 150 nm in diameter. They are specifically enriched with membrane markers such as Alix, CD63, and CD 9. Housed within exosomes are proteins, lipids, and nucleic acids which reflect the composition of the parent cell from which they originated. There is growing interest in exosomes in different disciplinary fields since these extracellular vesicles have been shown to be mediators of cell-to-cell communication. This study is divided into two parts: the first, to introduce a novel microfluidic design for isolation of exosomes on immunoaffinity capture, and the second, on the potential of glioma stem cell-derived exosomes for neuroregenerative properties. Currently available methods for exosome isolation, including ultracentrifugation, and filtration, are either time consuming, damages exosomes by sheering force, or produce impure yields of exosome isolates. Moreover, current immunocapture designs only employ one exosomal marker for isolating exosomes. This only captures a single subpopulation of exosomes and consequently gives a lower yield, as it has been shown that exosomes are highly heterogenous, with different exosomes presenting different specific markers on their surfaces. Thus, our present microfluidic design functionalized with three different exosome specific markers (CD63, CD9, and CD81) allows for isolation of different subpopulations of exosomes on a microfluidic device that is time efficient and simple to use. Gliomas are one of the most aggressive forms of cancer in the central nervous system, often resistant to treatment and recurring often. It was speculated that a subset of neural tumor stem cells in glioma tumors are responsible for their aggressive characteristics. Exosomes derived from other stem cells, such as mesenchymal stem cells, have been extensively studied for their therapeutic properties in neuroregeneration. We showed that bone marrow mesenchymal stem cell-derived exosomes and glioma stem cell-derived exosomes could enhance the length of neurite outgrowths on differentiated SH-SY5Y cells.