CHAPTER 4: Biological Characterization of Extracellular Vesicles – Methodologies to Characterize Molecular Composition of Extracellular Vesicles – Advances Towards Single Vesicle Characterization

Extracellular vesicles (EVs) are nanosized plasma membrane-derived particles originating from all cell types of our body. These enigmatic extracellular organelles act as multi-functional messengers between neighboring or distant cells. A common feature of all EVs is that they reflect the molecular composition of the original cell and carry all biomolecules, including lipids, proteins, nucleic acids and carbohydrates. Because all body fluids contain EVs, they act as the body's natural signal carriers and promising biomarkers in the form of liquid biopsies in many disease states, especially in cancer. However, the heterogeneity of EVs in biological and clinical samples impedes their reliable characterization. To understand this heterogeneity, it is becoming increasingly essential to develop methods for single vesicle analysis instead of bulk analyses. This chapter focuses on recent progress and challenges in the characterization of EVs in a single vesicle level.