Fig. 3

Macrophage polarization induced by sEV-AT. a Schematic view of the treatment process. M0 macrophages were induced into M1 macrophages by LPS. Then, the culture medium was removed, and h-sEV-AT was added to polarize M1 macrophages to M2 macrophages for 4 days. b Representative images of M1 macrophages (F4/80⁺iNOS⁺) and M2 macrophages (F4/80⁺CD206⁺) with immunofluorescence staining (green: F4/80, red: iNOS/CD206, blue: DAPI). Scale bar = 50 µm. c The percentage of M1 macrophages or M2 macrophages in total cells per field of view (scale bar = 50 µm) was analyzed by ImageJ software (n = 3). d The ratio of M2/M1 per field of view (scale bar = 50 µm) was analyzed (n = 3). e The expression of M1 macrophage marker genes (IL-6, IL-1β, TNFα, and iNOS) and M2 macrophage marker genes (Arg1, TGF-β1, IL-10, and CD206) was measured by qRT-PCR (n = 3). The significance was tested with an unpaired two-tailed Student’s t test. *p < 0.05, **p < 0.01, ***p < 0.001