Exosomes

They are a kind of extracellular vesicles with sizes between 30nm and 150nm. They partially overlap in size with Microvesicles, but their biogenesis is different. Exosomes are associated with endocytic pathway and with endosomal multivesicular bodies' formation[@pedrioli2021Extracellular Vesicles as Promising Carriers in Drug Delivery: Considerations from a Cell Biologist’s Perspective].

There are two known pathways for their biogenesis:

• ESCRT-dependent
  • Are enriched with syntenin-1 and ALG-2-interacting protein X (ALIX)
• ESCRT-independent
  • Are enriched with tetraspanins (CD9, CD63, CD81, see: CD9 and CD63 are used as biomarkers in EVs but they can change from cell line to cell line)