ExoAssay™ Cell Culture Supernatant Overall Exosome ELISA Kit

Extracellular vesicles (EVs) are particles with a lipid bilayer membrane structure that are produced during cellular activity and can be categorized as microvesicles, exosomes, and apoptotic vesicles depending on their size and biogenesis. Exosomes are between 40-160 nm in diameter, and they are distinguished from other vesicles by specific markers on their surface, such as TSG101, Alix, CD63, and CD81, in addition to differences in size and biogenesis. After exosomes are released from cells, some of them enter the plasma or other body fluid components and participate in in vivo pathophysiological activities by delivering substances and transmitting cellular information in vivo, which is clinically important in therapy and diagnosis. For example, changes in the contents of circulating exosomes in the blood when a virus infects the body can serve as a potential biomarker for disease diagnosis. Exosomes can be loaded with viral components, and detection of their contents can be used as a biomarker to determine disease progression and different viral infections.

Figure 1. Schematic illustration of the composition and membrane orientation of extracellular vesicles
(Source: Yang B, et al. 2019)

Exosomes carry a wide range of active ingredients and contain a variety of proteins, nucleic acids and lipids, all of which are of cellular origin. The content, size, and membrane composition of exosome contents are highly heterogeneous and dynamic, influenced by cellular origin, state, and environmental conditions. Since exosomes are responsible for the transportation of goods and information transfer between cells, researchers have begun to focus on their potential as drug delivery vehicles. Exosomes have many advantages such as low immunogenicity, low toxicity, the ability to cross natural barriers, and the ability to be engineered. The methods of exosome drug loading can be categorized into exogenous and endogenous drug loading. Exogenous drug loading refers to the direct loading of drug molecules onto purified exosomes, such as by electroporation, sonication, and extrusion. Endogenous drug loading is done by modifying exosome-derived mother cells to encapsulate the drug in exosomes to be secreted.

Figure 2. Schematic illustration of exosome nanotechnology for next-generation theranostic medicine
(Source: Yang B, et al. 2019)

At present, exosome drug delivery still has some problems during clinical application, such as the lack of standard separation and purification methods, limited drug loading efficiency, and the inability to achieve clinical-grade yields. In addition, there are no universal molecular markers to characterize all exosomes, and there is still a need to select markers based on specific sources and types of exosomes. The variability in the size of exosomes and the contents they contain has somewhat hindered the clinical use of exosomes. In conclusion, there are still some challenges in the clinical application of exosomes as delivery vehicles, but there is no doubt about their great potential in the biomedical field.

EXO ELISA Kit