Towards Therapeutic Delivery of Extracellular Vesicles: Strategies for In Vivo Tracking and Biodistribution Analysis

Figure 2

Schematic representation of different methods to promote tissue- or cell-type-specific targeting of extracellular vesicles (EVs). EVs can be targeted to particular cellular receptor either by modifications of EVs-producing cells (red squares) or modification of EVs after secretion (yellow squares). In the first case, EVs-producing cells can be modified: expressing ligands, peptides, or viral-derived envelop proteins in the outer portion of a transmembrane protein; loading cells with iron oxide particles to allow for magnetic targeting. Alternatively, secreted EVs can be modified linking cell-specific peptides to the EVs surface via association with polyethylene glycol (PEG) polymer chains or by EVs-liposome fusion. Click chemistry can be used to modify both EVs-producing cells and purified EVs.