Determining the Size Distribution and Integrity of Extracellular Vesicles by Dynamic Light Scattering.

Extracellular vesicles (EVs) have emerged as significant players in intercellular communication. They carry crucial biological information, and their uptake induces changes in the biological functioning and phenotypes of the recipient cell. Thus, there has been a great deal of interest in understanding their roles in the pathobiology of benign diseases and cancer. Moreover, EVs carry the molecular signatures of the donor cells, and therefore, their utility in biomarker development is being explored. Investigations are also underway to exploit their natural property of cargo transfer from one cell to another to develop efficient, nontoxic, and nonimmunogenic drug delivery systems. EVs originate through endosomal pathways, membrane-budding, or membrane-blebbing during apoptosis. These EV subtypes are usually expected to follow a specific size and surface marker distribution reflective of their origin; however, variations are often reported, especially under pathobiological conditions. Therefore, they are categorized mainly based on their size distribution as small, medium, and large EVs. Dynamic Light Scattering (DLS) is frequently used to measure the size distribution of nanoscale particles in a solution. Moreover, it also provides data on other biophysical properties such as polydispersity, aggregation, solubility, viscosity, and stability. This chapter describes the methods for determining the size distribution and integrity of EVs using DLS along with some constraints associated with the practical use of the technology.