Absolute sizing and label-free identification of extracellular vesicles by flow cytometry
||E. van der Pol, L. de Rond, F.A.W. Coumans, E.L. Gool, A.N. Böing, A. Sturk, R. Nieuwland, and T.G. van Leeuwen|
||Accepted December 15, 2017|
||Nanomedicine: Nanotechnology, Biology, and Medicine|
||van der Pol 2018 Nanomedicine Flow-SR.pdf (1,134 kB)|
||van der Pol 2018 Nanomedicine Flow-SR suppl.pdf (187 kB)|
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.