FIGURE 2.

Exosome biology. Exosomes originate from the late endocytic pathway through the formation of intraluminal vesicles (ILVs) and are then released from the cell surface by exocytosis. Upon targeting the recipient cell, exosomes engage with the surface molecules of the recipient cell to initiate downstream signaling or merge with the plasma membrane to unload their contents. Additionally, the internalization of exosomes is achievable through multiple routes, leading them to the early endosome, late endosome, or MVB. The exosome contents may be released into the nucleus or ER, traverse the cytosol, or be broken down in the lysosomes. Moreover, the recycling endosome allows exosomes to be rereleased into the external space. MVB, multivesicular body; ER, endoplasmic reticulum.