Update on the roles and applications of extracellular vesicles in depression

Figure 2 Overview of different extracellular vesicles and exosomal contents. A: Biogenesis of different extracellular vesicles (EVs). (1) Exosomes (30-150 nm) are secreted via exocytosis of intraluminal vesicles, which are formed by the inward budding of the endosomal membrane. The fusion of multivesicular bodies (MVBs) with the plasma membrane facilitates their release into the extracellular space (blue arrows); (2) Microvesicles (100-1000 nm) originate from the outward budding and shedding of the plasma membrane; (3) Apoptotic bodies (500 nm to 5 μm) are released as cell fragments during the final stages of apoptotic cell death; and (4) The fusion of autophagosome with MVBs generates amphisomes. These amphisomes fuse with the plasma membrane to release autophagic EVs (green arrows); B: Exosomes contents. Exosomes contain a variety of comprise surface markers such as membrane transport/fusion proteins, tetraspanins, immune regulators, adhesion molecules, and lipid rafts. The package contents of exosomes encapsulate diverse biomolecules, such as proteins, nucleic acids, lipids, metabolites, and other cellular components. EVs: Extracellular vesicles; MVBs: Multivesicular bodies; ICAM-1: Intercellular adhesion molecule 1. Created by Biorender.