Exosomes are extracellular vesicles (EVs) released by cells, which are present in biological fluids and in cell culture conditioned media. Their unique characteristics and involvement in cell signalling makes them a powerful tool for diagnosis and therapeutic applications.
The need to describe, detect, quantify, and track exosomes is unquestionable to provide consistency in studies and for further advances.
How to characterize exosomes?
Across their lipid bilayer membrane, exosomes contain transmembrane proteins, including the tetraspanins CD9, CD63, and CD81, widely recognized and popular exosome markers. Considering this, Cell Guidance Systems has developed a range of solutions based on exosome composition and characteristics, highlighting that all products are available for CD9, CD63, and CD81 proteins. For exosome characterization, we offer a large range of products depending on your needs: exosome marker antibodies, detection assay – TRIFic™ and tracking assay – ExoFLARE™.
TRIFic™ technology: exosome detection
The TRIFic™ exosome detection assay is an ELISA-like assay in the sense that it is an antibody sandwich-based assay for the detection of exosome particles. However, there are some significant differences. Unlike a standard ELISA assay, there is no enzymatic reaction. Rather, the exosome target is detected directly with a Europium labeled-antibody, constituting a time-resolved immunofluorescence assay.
The TRIFic™ exosome assays provide clear and consistent data quickly from purified or unpurified samples in a convenient 96-well format. The kit is available for marker proteins CD9, CD63, and CD81.
ExoFLARE™ technology: exosome tracking
The ExoFLARE™ exosome tracking assay allows for the detection and monitoring of exosomes in vitro and in vivo.
The ExoFLARE™ exosome tracking assay utilizes a combination of a FLARE (fluorescence activating response element) protein tag linked via a transmembrane domain to the individual tetraspanin proteins CD9, CD63, and CD81, together with a pro-fluorophore dye.
Neither the protein nor the dye fluoresce in isolation; fluorescence is only achieved when the protein binds to the dye. The protein and pro-fluorophore dye form an unstable bond with a continuous turnover of the dye, which causes a change in the chemical structure, resulting in fluorescence. The continuous turnover allows for sustained fluorescence without the levels of photo-bleaching commonly associated with fluorescent proteins.
The ExoFLARE™ assay can be monitored for extensive periods for tracking of the dye’s movement.
Exosome validated antibodies
The exosome marker antibodies have been validated against exosome-associated antigens CD9, CD63, and CD81 to characterize and/or quantify exosomes in cell culture media and biological fluids. The high-quality exosome validated antibodies have been specifically tested for western blotting, the most common method to assess the presence of proteins in EV samples.