Characterization of EV-loaded hydrogels. (A) Characterization of EVs. Adapted reprinted with permission from Ref. [175], Copyright @ 2020, Springer Nature B.V. (License number: 5,441,160,193,635). (B) Detection of exosomes on the hydrogel sponge. (ⅰ & ⅱ) SEM images of hydrogel surface. The black arrows show the exosomes; (ⅲ & ⅳ) LSCM images of the hydrogel sponge. Adapted reprinted with permission from Ref. [176], based on CC BY License, Copyright © 2017 Shi, Qian, Liu, Sun, Wang, Liu, Xu and Guo.(C) Controlled release of EVs in GelMA hydrogels. (ⅰ) 3D image of PKH67-labeled EVs incorporated in GelMA; (ⅱ) Overlapping image; (ⅲ) ELISA standard curve; (ⅳ) EVs releasing curve. Adapted reprinted with permission from Ref. [175], Copyright @ 2020, Springer Nature B.V. (License number: 5,441,160,193,635). (D) (ⅰ) 3D reconstruction image of GelMA hydrogels with PKH26 labeled EVs; (ⅱ) Representative confocal images of cells that were co-cultured with PKH26 labeled EVs (red). The nuclei were stained by DAPI (blue). (ⅲ) Representative in vivo imaging picture of retention of PKH26 labeled EVs after applied on wound 1, 2, 3, 4 days. Adapted reprinted from Ref. [72], with permission from Elsevier, Copyright© 2022 Acta Materialia Inc (License number: 5,419,380,313,323). . (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)