FIGURE 1.

EVs and their engineering and loading strategies. The figure displays the routine approach EV secreted from MSCs, and lists the mentioned modification methods simply, and the loading methods are demonstrated simultaneously. (A) EVs are routinely secreted by budding and exocytosis, which corresponds to different sizes of EVs, EV secreted by budding commonly possesses larger size, while EVs secreted by exocytosis is usually smaller. Otherwise, apoptosis vesicles only emerge during apoptosis happens. (B) EVs can be modified in different methods, including genetic engineering, chemical modification and non-covalent modification. (C) EVs can be loaded onto different forms of biomaterials, they are shown from left to right relatively.