Biogenic Nanotherapeutics group (BION) 1 article published in JoVE Bioengineering Evaluation of the Storage Stability of Extracellular Vesicles Maximilian Richter1,2, Kathrin Fuhrmann1, Gregor Fuhrmann1,2 1Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Biogenic Nanotherapeutics group (BION), 2Department of Pharmacy, Saarland University Here we present a readily applicable protocol to assess the storage stability of extracellular vesicles, a group of naturally occurring nanoparticles produced by cells. The vesicles are loaded with glucuronidase as a model enzyme and stored under different conditions. After storage, their physicochemical parameters and the activity of the encapsulated enzyme are evaluated.