Exosomes are common membrane-bound nanovesicles that contain diverse biomolecules, such as lipids, proteins, and nucleic acids. Exosomes are derived from cells through exocytosis, are ingested by target cells, and can transfer biological signals between local or distant cells. Exosome secretion is a constitutive phenomenon that is involved in both physiological and pathological processes and determines both the exosomal surface molecules and the contents. Hence, we can exploit exosomes as biomarkers, vaccines and drug carriers and modify them rationally for therapeutic interventions. However, it is still a challenge to identify, isolate and quantify exosomes accurately, efficiently and selectively. Further studies on exosomes will explore their potential in translational medicine and provide new avenues for the creation of effective clinical diagnostics and therapeutic strategies; the use of exosomes in these applications can be called exosome theranostics. Researchers from Zhejiang University discuss the fundamental processes of exosome formation and uptake. In addition, the physiological and pathological roles of exosomes in biology are also illustrated with a focus on how exosomes can be exploited or engineered as powerful tools in translational medicine.
Schematic representation of the primary strategies of exosome modification
and therapeutic intervention in translational medicine
Exosomes have the potential to serve as biomarkers and vaccine and drug carriers engineered by different methods. Such methods include the transfer of target peptide-expressing plasmids into cells to generate exosomes with a target ligand, the direct loading of drugs into exosomes by electroporation, the extrusion of drug-loaded cells through a series of filters with diminishing pore sizes to generate exosome-mimetic vesicles, and the fusion of exosomes with modified liposomes via the freeze-thaw method to create hybrid exosomes.