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 from the fact that exosomes size perfectly fits within the surface plasmon wave depth, allows the detection of multiple exosome subpopulations of neural origin directly in blood. By using 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 exosomes cellular origin. These results confirm the extreme variability of exosomes composition and how SPRi can provide an effective tool for their characterization. Besides, our work paves the road towards more precise clinical studies on the use of exosomes as potential biomarkers of neurodegenerative diseases.
ASJC Scopus subject areas
- Analytical Chemistry