Microprobe‐based technology for antigen‐specific purification of exosomes for OMICS analysis

Abstract

Exosomes encapsulate genomic and proteomic biomarkers for non‐invasive diagnosis and disease monitoring. However, exosome surface‐markers heterogeneity is a major drawback of current isolation methods. Here, we report a direct, one‐step exosome sampling technology, ExoPRIME, for selective capture of CD63+ exosome subpopulations using an immune‐affinity protocol. Microneedles (300μm × 30 mm), functionalized with anti‐ CD63 antibodies, were incubated under various experimental conditions in conditioned astrocyte medium and astrocyte‐derived exosome suspension. The probe’s capture efficiency and specificity were validated using Flu‐oroCet assay, immunofluorescent imaging, and OMICS analyses. Significantly higher exosomes were captured by probes incubated for 16 h at 4 0C in enriched exosomal suspension (23 × 10 6 exosomes per probe) vis‐'a‐vis 2 h at 4 0 C (12 × 10 6) and 16 h at 22 0C (3 × 10 6) in conditioned cell media. Our results demonstrate the application of ExoPRIME over a broad dynamic range of temperature and incubation parameters, offering flexibility for any desired application. ExoPRIME permits the use and re‐use of minimal sample volumes (≤200 μL), can be multiplexed in arrays, and integrated into a lab‐on‐a‐chip platform to achieve parallel, high‐throughput isolation of different exosome classes in a semi‐automated workstation. This platform could provide direct exosomal analysis of biological fluids since it can elegantly interface with existing room‐temperature, picomolar‐range nucleic acid assays to provide a clinical diagnostic tool at the point of care.