Table 1.

Characterization and Classification of Extracellular Vesicles.

Characterization	Exosomes	Microvesicles	Apoptotic bodies
Similarities	Present in all biofluids Released from almost all types of cells Includes proteins, lipids, and nucleic acids Isolation: (ultra) centrifugation Identification: electron microscope for morphology; NTA for size and concentration; western blot for biomarker expression Intercellular communication: transferring biologic information to recipient cells
Size (diameter)	~ 30-150 nm	~ 0.1-1 µm	1-5 µm
Formation	Fusion of MVB with cell membrane	Outward budding of the plasma membrane	Release after cell apoptosis
Formation pathways	ESCRT pathways; Tetraspanin or ceramide pathways	Various enzymes and mitochondrial or calcium signaling pathways (complex and unclear)	Apoptosis-related pathway
Markers	CD9, CD63, CD81 TSG 101, flotillin, annexin HSP70, HSP90	Integrins, selections, and other antigens from parent cells High phosphatidylserine exposure	High phosphatidylserine exposure Caspase 3, histones

NTA: nanoparticle tracking analysis; MVB: multivesicular bodies; ESCRT: endosomal sorting complex required for transport; CD: cluster differentiation; TSG: tumor susceptibility gene.