Fig. 2.

Exosome structure, formation, and delivery process. The plasma membrane invaginates to form early endosomes and then gradually forms late endosomes. Multivesicular bodies (MVBs) form by inward budding of the late endosomal limiting membrane. The MVB can either fuse with lysosomes or autophagosomes to be degraded or fuse with the plasma membrane to the release of late endosomal contents, i.e., intraluminal vesicles (ILVs) with a variety of information into the extracellular space to form exosomes. In the extracellular space, exosomes can be taken up by recipient cells via three patterns: receptor–ligand binding, endocytosis, or membrane fusion