The CS hydrogel preparation was based on previous studies [32 (link)]. Briefly, to obtain a 2% CS hydrogel, 50% β-glycerophosphate (Macklin, Shanghai, China) solution was added to a 2% CS (Macklin, Shanghai, China) solution at a 5:1 vol ratio on ice with constant stirring until the two solutions were completely mixed. For the preparation of CS hydrogel loaded with DPSC-Exo, the DPSC-Exo solution was mixed with 2% CS hydrogel at a 1:1 vol ratio. Then, the mixture was incubated at 37 °C for 30 min to cross-link into the hydrogel. The final concentration of CS was 1%.
The release profile of DPSC-Exo/CS was detected according to previous studies [32 (link),36 (link)]. Briefly, 100 μl of DPSC-Exo/CS was placed in a transwell chamber inserted in a 24-well plate and incubated with 500 μl of PBS at 37 °C. A volume of 10 μl of the supernatants was collected and replaced by the same volume of fresh PBS on the indicated days. The concentration of released exosomes was tested with the BCA Protein Assay Kit.
The release profile of DPSC-Exo/CS was detected according to previous studies [32 (link),36 (link)]. Briefly, 100 μl of DPSC-Exo/CS was placed in a transwell chamber inserted in a 24-well plate and incubated with 500 μl of PBS at 37 °C. A volume of 10 μl of the supernatants was collected and replaced by the same volume of fresh PBS on the indicated days. The concentration of released exosomes was tested with the BCA Protein Assay Kit.