Exosomes

Exosomes are small extracellular vesicles released by cells that can transport proteins, lipids, RNA and other molecules between cells. These nanoscale particles participate in intercellular communication and are widely investigated as potential biomarkers, delivery systems and sources of information about physiological and pathological processes.

What are exosomes?

Exosomes belong to the broader group of extracellular vesicles, or EVs, which are lipid bilayer-delimited structures released by different cell types. In the strict biological sense, the term exosome is associated with an endosomal origin. Their formation involves multivesicular bodies followed by the release of vesicles into the extracellular environment when these compartments fuse with the plasma membrane.

Because different extracellular vesicle populations can share similar physical characteristics, size or concentration alone is generally insufficient to establish biological origin. Experimental studies therefore commonly combine isolation methods, physical characterization and analysis of markers associated with the investigated populations.

How are exosomes analyzed?

Exosome analysis can involve complementary techniques to determine particle size, concentration, morphology, molecular composition and surface properties. Nanoparticle tracking analysis, or NTA, is one approach used to track the movement of individual particles in suspension and estimate their size distribution and concentration.

When researchers need to investigate specific vesicle populations, fluorescence-based measurements can provide additional information about particle-associated markers. Platforms such as ZetaView Evolution combine NTA with capabilities for fluorescence analysis, zeta potential and nanoparticle characterization, supporting more detailed studies of extracellular vesicles and their subpopulations.

Applications of exosomes in laboratory research

Exosome research has applications across life sciences, biotechnology and biomedical research. Because their molecular composition can reflect characteristics of their cells of origin, these vesicles are investigated both to understand biological mechanisms and to develop new analytical and therapeutic strategies.

• Biomarker research in biological fluids.
• Studies of intercellular communication.
• Cancer and disease research.
• Development of molecular delivery systems.
• Characterization of extracellular vesicles from cell cultures.
• Analysis of proteins, lipids and nucleic acids carried by EVs.
• Research in regenerative medicine and vesicle-based therapies.

Characterization of exosomes and extracellular vesicles

Reliable characterization generally depends on combining different types of experimental information. Particle size distribution and concentration describe important physical characteristics, while marker analysis and complementary methods can provide additional evidence about identity, purity and heterogeneity.

This is particularly relevant because preparations obtained from biological fluids or conditioned cell culture media may contain different extracellular vesicles, non-vesicular particles and other components. The selection of analytical methods should therefore be guided by the scientific question and the characteristics of the sample.

What is the difference between exosomes and extracellular vesicles?

Extracellular vesicle is a broad term for lipid bilayer-delimited particles naturally released by cells. Exosomes represent a class historically associated with the endosomal pathway. When the biogenesis of a vesicle has not been demonstrated, broader terminology may be more appropriate.

What is the size of exosomes?

Exosomes are generally described as nanoscale vesicles, but their size range can overlap with other extracellular vesicle populations. Therefore, particle size alone should not be considered definitive evidence that a particle is an exosome.

How are exosomes measured?

Exosomes and other extracellular vesicles can be investigated using several complementary techniques. NTA can determine particle size distribution and concentration in suspension, while fluorescence analysis, microscopy, biochemical methods and marker detection can provide additional information about the population being studied.