Detection and Characterization of Different Brain-Derived Subpopulations of Plasma Exosomes by Surface Plasmon Resonance Imaging

Abstract

The use of exosomes for diagnostic and disease monitoring purposes is becoming particularly appealing in biomedical research because of the possibility to study directly in biological fluids some of the features related to the organs from which exosomes originate. A paradigmatic example are brain-derived exosomes that can be found in plasma and used as a direct read-out of the status of the central nervous system (CNS). Inspired by recent remarkable development of plasmonic biosensors, we have designed a surface plasmon resonance imaging (SPRi) assay that, taking advantage of the fact that exosome size perfectly fits within the surface plasmon wave depth, allows the detection of multiple exosome subpopulations of neural origin directly in blood. By use of an array of antibodies, exosomes derived from neurons and oligodendrocytes were isolated and detected with good sensitivity. Subsequently, by injecting a second antibody on the immobilized vesicles, we were able to quantify the amount of CD81 and GM1, membrane components of exosomes, on each subpopulation. In this way, we have been able to demonstrate that they are not homogeneously expressed but exhibit a variable abundance according to the exosome cellular origin. These results confirm the extreme variability of exosome composition and demonstrate how SPRi can provide an effective tool for their characterization. Besides, our work paves the road toward more precise clinical studies on the use of exosomes as potential biomarkers of neurodegenerative diseases.

Simple and Fast SEC-Based Protocol to Isolate Human Plasma-Derived Extracellular Vesicles for Transcriptional Research

“…Extracellular vesicles (EVs) have emerged as promising shields of disease-specific or therapeutic RNAs. 1 , 2 , 3 , 4 EVs comprise a heterogeneous population of membranous structures that are naturally released from all cell types into the extracellular space. These structures carry a variety of molecules that reflect the biomolecular composition of the tissue and cells of origin.…”

Augmented COlorimetric NANoplasmonic (CONAN) Method for Grading Purity and Determine Concentration of EV Microliter Volume Solutions

“…In this paper, we present a step-by-step protocol to assign a purity grade and to subsequently titrate EV formulations by an augmented microplate version of the COlorimetric NANoplasmonic (CONAN) assay (Maiolo et al, 2015;Mallardi et al, 2018;Picciolini et al, 2018;Gualerzi et al, 2019;Rojalin et al, 2019) with an optimized balance between robustness and accessibility.…”

Noble Metal-Assisted Surface Plasmon Resonance Immunosensors

“…The substrate used for reported SPR biosensors for exosome detection has been primarily based on Au-based plates. Picciolini et al demonstrated the SPR imaging assay using an antibody array, which could bind to the surface protein of the exosome, on an Au plate for the separation and characterization of multiple exosomes from diverse neuronal cells [84] (Figure 7a). Exosomes from oligodendrocytes and neurons were measured with high sensitivity and selectivity.…”