Extracellular vesicles (EVs) have stimulated considerable scientific and clinical interest, yet protein profiling and sizing of individual EVs remains challenging due to their small particle size, low abundance of proteins, and overall heterogeneity. Building upon a laboratory-built high-sensitivity flow cytometer (HSFCM), we report here a rapid approach for quantitative multiparameter analysis of single EVs down to 40 nm with an analysis rate up to 10 000 particles per minute. Statistically robust particle size distribution was acquired in minutes with a resolution and profile well matched with those of cryo-TEM measurements. Subpopulations of EVs expressing CD9, CD63, and/or CD81 were quantified upon immunofluorescent staining. When HSFCM was used to analyze blood samples, a significantly elevated level of CD147-positive EVs was identified in colorectal cancer patients compared to healthy controls (P < 0.001). HSFCM provides a sensitive and rapid platform for surface protein profiling and sizing of individual EVs, which could greatly aid the understanding of EV-mediated intercellular communication and the development of advanced diagnostic and therapeutic strategies.
Keywords: cancer diagnosis; exosomes; extracellular vesicles; flow cytometry; protein profiling; sizing; subpopulation identification.