Abstract

Extracellular Vesicles (EVs) and Cell Free DNA (cfDNA) as Blood-based Biomarkers: Plastic-based Microfluidics for their Enrichment and Analysis

Steve Soper, Foundation Distinguished Professor; Director, Center of BioModular Multi-scale System for Precision Medicine, Adjunct Professor, Ulsan National Institute of Science & Technology, The University of Kansas

While there are a plethora of different blood-based markers, EVs are generating significant interests due to their relatively high abundance (~10¹³ particles per mL of blood) and the information they carry. EVs contain a diverse array of nucleic acids, such as mRNA, lncRNA, and miRNA that can be used for disease management. In addition to EVs, cfDNA also are biomarkers that can be used to help manage different disease states using the mutations they possess that can have high diagnostic value. In spite of the relatively high abundance of cfDNA in diseased patients (~160 ng/mL), the extraction and enrichment of cfDNA has been inefficient, even by commercial kits, due to the low abundance of the tumor bearing DNA fragments (<0.01%) and the short nature of these fragments, especially cancer-related cfDNA (as small as 50 bp). In this presentation, we will discuss the design, fabrication and analytical figures-of-merit of a microfluidic device that can serve the dual purpose for the affinity-based selection of EVs and the solid phase extraction of cfDNA directly from plasma using the same device. The microfluidic is made from a plastic that can be injection molded to produce high quality devices at low cost. For EVs, the device is made cyclic olefin copolymer (COC) is UV/O3 activated to allow for the efficient immobilization of affinity agents to the surface of the device. In the case of cfDNA, the device is made from COC as well, but is only UV/O3 activated (i.e., no affinity agents used). Information will be provided as to the ability to molecularly profile the cargo contained within the affinity-selected EVs, in particular mRNA expression profiling. We will also discuss the use of this microfluidic to isolate with high recovery cfDNA from plasma samples with size selection capabilities. The isolated cfDNA could be queried for mutations using an allele-specific ligation detection reaction at a mutant to wild-type ratio <0.1%.