Fig. 2

The processes of exosome biogenesis and release. a Biogenesis and release of exosomes. Exosome biogenesis originates from plasma membrane endocytosis, followed by maturation of early endosomes as MVBs. During this process, ILVs (exosomes) are formed within MVBs by ESCRT-dependent or ESCRT-independent pathways. In secretory cells, MVBs can be degraded by lysosomes or fused with the plasma membrane to release ILVs as exosomes with the assistance of Rab27a/b. b The contents of exosomes. Exosomes contain a variety of intrinsic components and variable cargoes, varying from proteins, lipids, metabolites, and DNAs to ncRNAs. c Interaction between exosomes and the target cells. In target cells, exosomes can directly bind with surface receptors to trigger intercellular signaling. Alternatively, exosomes can be internalized via endocytosis or direct fusion and liberate their cargoes into the target cells, thus mediating multiple physiological and pathological processes. MVBs multivesicular bodies, ILV intracavitary vesicles, ESCRT endosomal sorting complexes required for transport