Figure 2.

EV biogenesis, release, and uptake. Internal budding of early endosomes results in the formation of intraluminal vesicles (ILVs) that contain cytosolic components (proteins, mRNAs, miRs). ILVs are contained within multivesicular bodies (MVBs) that may fuse with the plasma membrane, resulting in the liberation of their vesicles into the extracellular space, at which point the vesicles become exosomes. Microvesicles (MVs) are formed by the budding of the plasma membrane, resulting in the vesicular entrapment of free cytoplasmic components and the liberation of the MVs into the extracellular space. Both populations of vesicles (exosomes, MVs) are collectively termed EVs and are challenging to discriminate from each other once they have been released from the producer cells. The molecular cargo in EVs may be delivered to target cells by a variety of mechanisms that may involve fusion, endocytosis and/or receptor–ligand interactions.