Absolute sizing and label-free identification of extracellular vesicles by flow cytometry

• Published in: Nanomedicine Vol. 14; no. 3; pp. 801 - 810
• Main Authors: van der Pol, Edwin, de Rond, Leonie, Coumans, Frank A.W., Gool, Elmar L., Böing, Anita N., Sturk, Auguste, Nieuwland, Rienk, van Leeuwen, Ton G.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2018
• Subjects: Cell Size; Drug delivery; exosomes; extracellular vesicles; Extracellular Vesicles - physiology; Extracellular Vesicles - ultrastructure; flow cytometry; Flow Cytometry - methods; Humans; Lipoproteins - chemistry; Lipoproteins - ultrastructure; Microscopy, Electron, Transmission; nanomedicine; nanoparticles; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Particle Size; Plasma - chemistry; Refractometry; nanomedicine; Drug delivery; flow cytometry; extracellular vesicles; nanoparticles; exosomes
• ISSN: 1549-9634; 1549-9642
• DOI: 10.1016/j.nano.2017.12.012

Blood contains extracellular vesicles (EVs), which are biological nanoparticles with clinical applications. In blood plasma, EVs are outnumbered by similar-sized lipoprotein particles (LPs), leading to controversial data such as non-specific binding of antibodies to LPs. Flow cytometry is a clinically applicable technique to characterize single EVs in body fluids. However, flow cytometry data have arbitrary units, impeding standardization, data comparison, and data interpretation, such as differentiation between EVs and LPs. Here we present a new method, named flow cytometry scatter ratio (Flow-SR), to relate the ambiguous light scattering signals of flow cytometry to the diameter and refractive index (RI) of single nanoparticles between 200-500 nm in diameter. Flow-SR enables label-free differentiation between EVs and LPs and improves data interpretation and comparison. Because Flow-SR is easy to implement, widely applicable, and more accurate and faster than existing techniques to size nanoparticles in suspension, Flow-SR has numerous applications in nanomedicine. Blood contains extracellular vesicles (EVs) with clinical information. Flow cytometry is a clinically applicable technique to characterize single EVs in body fluids. However, flow cytometry data have arbitrary units, thereby impeding data comparison, data interpretation, and differentiation between EVs and similar-sized lipoprotein particles (LPs). Here we present a new method, named Flow-SR, to relate the ambiguous light scattering signals of flow cytometry to the diameter and refractive index (RI) of nanoparticles between 200-500 nm in diameter. Flow-SR enables label-free differentiation between EVs and LPs, improves data interpretation and comparison, and is therefore essential to research on EVs and other nanoparticles. [Display omitted]