Preparation of Small Extracellular Vesicles Using Sequential Ultrafiltration with Regenerated Cellulose Membranes of Different Molecular Weight Cutoffs: A Study of Morphology and Size by Electron Microscopy

Abstract There is still room for improvement in the isolation and purification techniques for extracellular vesicles (EVs), particularly in the separation of exosomes (small EVs) from other membrane vesicles such as microvesicles and apoptotic bodies. Furthermore, it is crucial to establish preparation methods that preserve the intrinsic properties of EVs in this context. In this study, we focus on the isolation and preparation of small EVs, exosomes, from the culture supernatant of a human cell line. We discuss the sequential use of regenerated cellulose membranes with different molecular weight cutoffs, based on direct evaluation by transmission electron microscopy, and examine the challenges of characterizing biological membrane vesicles, small EVs, identified during this process.