Fig. 1

Biogenesis, release, and internalization of exosomes. Exosomes originate from early endosomes which then mature to late endosomes or MVBs. Numerous proteins, nucleic acid, and lipids are selectively encompassed in exosomes during the formation of ILV inside MVBs via the invagination of the endosomal membrane. Eventually, exosomes are released outside the cell upon fusion of MVBs with the plasma membrane. The internalization of exosomes by recipient cells can be mediated by receptor-mediated endocytosis, macropinocytosis, phagocytosis, or direct fusion of exosomes with cell membrane