Overview and Update on Extracellular Vesicles: Considerations on Exosomes and Their Application in Modern Medicine

Simple Summary Exosomes are a subpopulation of extracellular vesicles, nanosized particles, lipid bilayer-enclosed, naturally secreted from cells after the fusion of intracellular Multivesicular bodies with the plasma membrane. Their components are proteins, nucleic acids, lipids, and metabolites by which they can act as mediators of cell-to-cell communication. They play a key role in regulating pathophysiological processes, such as immune response, neuronal communication, cancer biogenesis, and regulation. Therefore, they have been largely exploited for their potential therapeutic and diagnostic application. Due to their endogeneity, exosomes present superior biocompatibility and stability in comparison to synthetic carriers, and then they can be used as delivery vehicles. Herein, reviewing recent studies, information on exosome biogenesis, structural characteristics, isolation, and detection current methods is summarized. Further, the obstacles to overcome in the application of exosomes as delivery systems are also considered. In recent years, there has been a rapid growth in the knowledge of cell-secreted extracellular vesicle functions. They are membrane enclosed and loaded with proteins, nucleic acids, lipids, and other biomolecules. After being released into the extracellular environment, some of these vesicles are delivered to recipient cells; consequently, the target cell may undergo physiological or pathological changes. Thus, extracellular vesicles as biological nano-carriers, have a pivotal role in facilitating long-distance intercellular communication. Understanding the mechanisms that mediate this communication process is important not only for basic science but also in medicine. Indeed, extracellular vesicles are currently seen with immense interest in nanomedicine and precision medicine for their potential use in diagnostic, prognostic, and therapeutic applications. This paper aims to summarize the latest advances in the study of the smallest subtype among extracellular vesicles, the exosomes. The article is divided into several sections, focusing on exosomes' nature, characteristics, and commonly used strategies and methodologies for their separation, characterization, and visualization. By searching an extended portion of the relevant literature, this work aims to give a quick outline of advances in exosomes' extensive nanomedical applications. Moreover, considerations that require further investigations before translating them to clinical applications are summarized.