What are exosomes?
Exosomes are extracellular vesicle granules with a diameter of about 50 to 150 nm wrapped in a lipid bilayer secreted by various cells, and contain nucleic acids such as miRNA and mRNA, proteins, and lipids. They present in various body fluids such as blood, urine, breast milk, saliva and sweat and circulate in the body. Exosomes are involved in various biological phenomena by the delivery of these inclusions between cells through themselves. At the same time, they play an important role in the mechanism of onset and progression of many diseases including cancer.
Secretion pathway of exosomes
- Endosomes formed by endocytosis first form early endosomes and then transition to late endosomes.
- The late endosomes form multivesicular endosomes (MVBs: Multivesicular bodies) containing a large number of intraluminal membrane vesicles (ILVs) that form inwardly constricted to germinate.
- When these MVBs fuse with the cell membrane, ILVs are released extracellularly. These are considered exosomes.
＜References: "The role of exosomes in cancer progression and their potential for clinical application" (Fumihiko Urabe / Nobuyoshi Kosaka / Takahiro Ochiya), "Structural characteristics and functional control of extracellular vesicles" (Shimoda Asako / Shinichi Sawada / Kazunari Akiyoshi), Brain Science Dictionary＞