Exosomes as targeted diagnostic biomarkers: Recent studies and trends

Different categories of extracellular vesicles (EVs) are identified based on their origin and formation processes. Among these, exosomes (EXOs) originate from endosomal compartments merging with the plasma membrane, forming small lipid vesicles that transport a range of molecular cargo such as nucleic acids, proteins, and lipids. The composition of EXOs varies depending on their cellular source, encompassing various cell types, including neutrophils, dendritic cells, and even tumor cells. Remarkably, EXOs possess inherent stability, low immunogenicity, and compatibility, making them efficient nano vectors for drug delivery. Imaging techniques like bioluminescence, fluorescence, and nuclear imaging are crucial in non-invasively tracking EXOs within living organisms. This process requires the attachment of radionuclides to the EXO's structure without altering its essential characteristics. Real-time imaging of EXOs is vital for their clinical application, and recent advancements in labeling and tracking methodologies provide insights into biodistribution, functionality, and potential pathways for EXO-mediated drug delivery. This review presents updated progress in the diverse applications of EXOs in targeted imaging across various modalities, where they function as contrast agents facilitating tissue visualization and disease tracking. Consequently, EXOs emerge as promising entities in medical diagnostics and imaging.