Mesenchymal stromal cells (MSCs) are multipotent progenitors that can be isolated from different sources, such as the bone marrow, adipose tissue and umbilical cord. The therapeutic potential of MSCs is related to a plethora of immunomodulatory, anti-inflammatory and pro-repair actions, which are at least partially dependent on their secretome. Among the components of MSCs' secretome, EVs have received considerable attention because MSC-EVs exert similar therapeutic properties as their parent cells. Among the different MSC sources for EV production, human umbilical cord MSCs (hUCMSCs) show advantages such as tissue availability, high proliferative profile of the cells and potential beneficial therapeutic effects in a variety of different diseases, such as stroke This study aimed to provide novel insights for future hUCMSC-EVs research and treatment selection. We investigated the influence of the culture and harvesting conditions on the EV proteomic profile, productivity, surface markers expression and evaluated their in vivo biodistribution and toxicity.