Fluorescent labeled Exosome Standards

Extracellular vesicles (EVs) are a class of bilayer lipid vesicles released by cells, which can be categorized into microvesicles, exosomes, and apoptotic vesicles based on their different sizes and dimensions, mode of formation, and properties. Exosomes (EXOs) are produced by intraluminal vesicles (ILVs) during the maturation of multivesicular endosomes (MVEs) or multivesicular bodies (MVBs) and are secreted when MVEs fuse with the cell surface. Exosomes range from 40nm-160nm in diameter, have a bilayer lipid membrane structure, and can be produced by cells of almost different tissue types and physiological states. They are rich in cell-derived constituents such as DNA, RNA, lipids, metabolites, cytosolic proteins and surface proteins that are involved in physiological and pathological processes including intercellular communication, tissue regeneration and tumor invasion. For example, cell-derived exosomes participate in the StAR signaling pathway to inhibit testosterone biosynthesis by mediating the transfer of miR-9-3P from supporting cells to testicular mesenchymal stromal cells.

Figure 1. Biogenesis and identification of exosomes
(Source: Kalluri R, et al. 2020)

Exosomes are found in a variety of environments including blood, urine, saliva, tears and feces. A variety of separation methods have been developed for this purpose, including ultracentrifugation, size exclusion chromatography, ultrafiltration and immunoaffinity methods. Although these methods are based on different principles, they have their own advantages for different environments and application needs. Ultracentrifugation can generate centrifugal forces of up to 1,000,000 × g, making it the optimal process for the separation of small particles such as bacteria, viruses, and organelles. As such, it is the most translatable means of exosome isolation and has contributed to many groundbreaking exosome studies as the current gold standard. Differential ultracentrifugation has been widely used to isolate exosomes from a variety of sources (e.g., cell culture media, serum, saliva, urine, and cerebrospinal fluid), where cellular debris is removed at low centrifugal forces (300 g) and high centrifugal forces (100,000 g) are used to precipitate and concentrate exosomes. Subsequently, a class of non-specific extraction methods based on the physical properties of exosomes, such as polymer precipitation, size exclusion chromatography, ultrafiltration, etc., has been developed, in addition to a class of specific extraction methods based on the biological properties of exosomes, such as enrichment based on the principle of immunoaffinity and the principle of the interaction of glycans and lectins to enrich the corresponding exosomes.

Creative Diagnostics provides fluorescently labeled exosome standards for quality assessment and side controls related to exosome experiments.

Fluorescent labeled EXO standards