Fig. 4

Effect of different scaffolds on the inflammatory macrophage polarization. A Confocal microscopy imaging of exosomes released from PLA-Exo scaffold internalization into pro-inflammatory macrophages. Cells were stained with DAPI (blue) and examined by a confocal laser scanning microscopy. B Representative confocal microscopy images of pro-inflammatory macrophages response to different scaffolds. Cells were fixed, stained for phalloidin (red), nuclei (blue) and visualized by a confocal laser scanning microscopy. C Representative CLSM images showing the changes of intracellular ROS levels. Nuclei were stained with Hoechst 33342 (blue). D ROS intensity detection using flow cytometry. Intracellular ROS levels decrease following PLA-Exo scaffold treatment: **** p < 0.0001. E qRT-PCR results of relative gene expression of pro-inflammatory cytokine. The values were normalized to GAPDH as a housekeeping gene. Significant difference (*p < 0.05, ****p < 0.0001). Group a = control, group b = PLA scaffold, group c = PLA-Exo scaffold