Exosome (vesicle)

Exosomes, ranging in size from 30 to 150 nanometers, are membrane-bound extracellular vesicles (EVs) that are produced in the endosomal compartment of most eukaryotic cells. In multicellular organisms, exosomes and other EVs are found in biological fluids including saliva, blood, urine and cerebrospinal fluid. EVs have specialized functions in physiological processes, from coagulation and waste management to intercellular communication. Exosomes are formed through the inward budding of a late endosome, also known as a multivesicular body (MVB). The intraluminal vesicles (ILVs) of the multivesicular body (MVB) bud inward into the endosomal lumen. If the MVB fuses with the cell surface (the plasma membrane), these ILVs are released as exosomes. Exosomes were also identified within the tissue matrix, coined Matrix-Bound Nanovesicles (MBV). They are also released in vitro by cultured cells into their growth medium. Enriched with a diverse array of biological elements from their source cells, exosomes contain proteins (such as adhesion molecules, cytoskeletons, cytokines, ribosomal proteins, growth factors, and metabolic enzymes), lipids (including cholesterol, lipid rafts, and ceramides), and nucleic acids (such as DNA, mRNA, and miRNA). Since the size of exosomes is limited by that of the parent MVB, exosomes are generally thought to be smaller than most other EVs, from about 30 to 150 nanometres (nm) in diameter: around the same size as many lipoproteins but much smaller than cells. Compared with EVs in general, it is unclear whether exosomes have unique characteristics or functions or can be separated or distinguished effectively from other EVs. EVs in circulation carry genetic material and proteins from their cell of origin, proteo-transcriptomic signatures that act as biomarkers. In the case of cancer cells, exosomes may show differences in size, shape, morphology, and canonical markers from their donor cells. They may encapsulate relevant information that can be used for disease detection....