Extracellular vesicles (EVs) are biological nanoparticles comprising exosomes, microvesicles, and other heterogeneous nanoscopic vesicle populations that are produced by most cell types. In addition to their putative roles as critical mediators of intercellular communication, EVs have begun to be harnessed as drug delivery vehicles, with early evidence indicating they may have significant advantages over synthetic nanoparticle delivery systems for particular applications. Targeted delivery of EV-encapsulated cargo has already been realized and may have broad applicability; however, methods for producing and purifying EVs and loading them with therapeutic molecules have yet to be standardized. In this chapter, we outline steps for EV isolation and characterization and compare current methods for active and passive loading of EVs with payloads of short interfering RNA (siRNA) or small molecules, with the results revealing that active loading via electroporation increases loading efficiency of siRNA but not of Rhodamine B, a model for a small molecule drug, in HEK293T-derived EVs. The methods described here may inform future design of targeted delivery of nucleic acids or small molecules via EVs.
Keywords: Cancer therapeutics; Drug delivery; Electroporation; Exosomes; Extracellular vesicles (EVs); Small molecules; siRNA.