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Updated: May 2, 2026
Author Spotlight: Advancing the Analysis of Plasma Extracellular Vesicle Proteome for Cardiovascular Biomarker Studies
Published on: January 31, 2025
Extracellular vesicles from blood plasma: determination of their morphology, size, phenotype and concentration
1Imagerie Moléculaire et NanoBioTechnologie, UMR-5248-CBMN CNRS-University of Bordeaux-IPB, Pessac, France.
Background:
Plasma and other body fluids contain membranous extracellular vesicles (EVs), which are considered to derive from activated or apoptotic cells. EVs participate in physiological and pathological processes and have potential applications in diagnostics or therapeutics. Knowledge on EVs is, however, limited, mainly due to their sub-micrometer size and to intrinsic limitations in methods applied for their characterization.
Objectives:
Our aim was to provide a comprehensive description of EVs from plasma of healthy subjects.
Methods:
Cryo-transmission electron microscopy combined with receptor-specific gold labeling was used to reveal the morphology, size and phenotype of EVs. An original approach based on sedimentation on electron microscopy grids was developed for enumerating EVs. A correlation was performed between conventional flow cytometry and electron microscopy results.
Results:
We show that platelet-free plasma samples contain spherical EVs, 30 nm to 1 μm in diameter, tubular EVs, 1-5 μm long, and membrane fragments, 1-8 μm large. We show that only a minority of EVs expose the procoagulant lipid phosphatidylserine, in contrast to the classical theory of EV formation. In addition, the concentrations of the main EV sub-populations are determined after sedimentation on EM grids. Finally, we show that conventional flow cytometry, the main method of EV characterization, detects only about 1% of them.
Conclusion:
This study brings novel insights on EVs from normal plasma and provides a reference for further studies of EVs in disease situations.
Insights
Extracellular vesicles (EVs) in plasma are diverse in size and shape, with most not exposing phosphatidylserine. Conventional flow cytometry significantly underestimates EV numbers, highlighting the need for advanced characterization methods.
Area of Science:
- Biochemistry and Molecular Biology
- Cell Biology
- Nanotechnology
Background:
- Extracellular vesicles (EVs) are found in body fluids and play roles in physiological and pathological processes.
- Limited knowledge of EVs is due to their small size and characterization method limitations.
- EVs hold potential for diagnostic and therapeutic applications.
Purpose of the Study:
- To comprehensively characterize extracellular vesicles (EVs) from healthy human plasma.
- To establish a reference for EV studies in disease contexts.
Main Methods:
- Cryo-transmission electron microscopy with gold labeling for EV morphology, size, and phenotype.
- Sedimentation on electron microscopy grids for EV enumeration.
- Correlation analysis between flow cytometry and electron microscopy.
Main Results:
- Plasma EVs include spherical (30 nm-1 μm), tubular (1-5 μm), and membrane fragments (1-8 μm).
- A minority of EVs expose phosphatidylserine, challenging classical formation theories.
- Conventional flow cytometry detects only ~1% of EVs compared to electron microscopy.
Conclusions:
- This study provides novel insights into the characteristics of EVs in normal plasma.
- The findings offer a baseline for future research on EVs in various disease states.
- Advanced methods are crucial for accurate EV characterization.
