Figure 3.

Schematic representation of exosome biogenesis, release and intercellular communication. Exosomes originate from an endocytic compartment. The inward budding of plasma membrane forms an early endosome. During maturation of the early endosome, the inward budding of limited areas of the endosomal membrane to form intraluminal vesicles (ILVs) produces multivesicular bodies (MVBs). MVBs face two fates, where some of them are delivered to lysosomes or autophasomes for degradation, while others fuse with the plasma membrane, inducing the secretion of exosomes. During the inward process of ILVs, many cytoplasmic components are encapsulated, such as proteins, lipids and nucleic materials, so they represent a new signalling paradigm to interfere with cell-to-cell communication. Moreover, this intercellular signal transmission might be mediated through three pathways, including endocytosis/internalisation, direct membrane fusion and receptor–ligand interaction [19].