Abstract All cells release small extracellular vesicles (EVs) that can carry cargo to other cells to affect their function. Mesenchymal stromal cells (MSCs) release EVs that have regenerative activities in vitro and in vivo and which represent potentially valuable new therapeutics. The realization of this potential is hindered by a lack of analytical methods to characterize MSC EVs, determine their mechanisms of action, and establish potency and dosage criteria. We will produce high resolution analysis tools for MSC EVs that will address these limitations and enable their development as new therapeutic entities.