Fig. 1.

Biogenesis of exosomes and the process of their release to different target cells

Inward budding of the cellular plasma membrane forms an early intracellular vesicle. Invagination of the early intracellular vesicle forms an intraluminal vesicle (ILV). This mature ILV gradually forms the multivesicular body (MVB). The MVB fuses with lysosomes, leading to digestion of its contents, or fuses with the cell membrane, releasing the exosomes out into the extracellular space. Exosomes containing integrins α₆β₄ and α₆β₁ are likely to target lung cells, while those containing integrin α_vβ₆ are more likely to be delivered to Kupffer liver cells. Macrophages recognize the exosomes containing phosphatidylserine (PS)