Figure 2.

Schematic representation of extracellular vesicles biogenesis. Extracellular and plasma membrane molecules are engulfed by plasma membrane endocytosis, creating the early endosomes. These are converted into late endosomes called multivesicular bodies (MVB) containing intraluminal vesicles (ILV). The MVBs may either fuse with the plasma membrane and empty their ILVs by exocytosis, termed exosomes, or may be converted into lysosomes and degrade their components. The process of microvesicle formation is calcium dependent and comes from direct shedding from outward cellular membrane budding; thereby carrying membrane markers of the parent cell. Apoptotic bodies are produced by secreting cells undergoing programmed cell death. Extracellular vesicle uptake by recipient cells may occur via fusion of the vesicle membrane with the cell membrane or by endocytosis. The vesicle may also transduce an intracellular signal by ligand binding to a receptor on the recipient cell. Abbreviations: MHC—major hystocompatibility complex; ER—endoplasmic reticulum; MVB—multivesicular bodies; ILV—intraluminal vesicles.