Fig. 4

MSC-sEV promoted wound closure and blood vessel formation in natural aging and type-2 diabetes mice models. a Representative cutaneous wound photographs in senescent C57BL/6mice model at days 0, 3, 6, 9, and 12 after the operation treated with PBS (control), MSC-sEV 200 μg around wounds (scale bar, 5 mm). b Quantification of the wound areas during the wound-healing process. n = 6, ***p < 0.001 at Day 12. c H&E staining of the skin tissue around the wound at day 12 after the operation (horizontal arrows indicated the scar width; scale bar, 1 mm). d Quantification of the scar width and percentage of re-epithelialization around the wound. n = 6, **p < 0.01. e Representative immunofluorescence staining images positive cells of CD31 (green staining) and DAPI in paraffin-embedded sections of senescent C57BL/6mice dorsal skin injected PBS (control) or MSC-sEV. Red arrows indicate tubes formed around the wound (scale bar, 200 μm). f Quantification of vessels formed around the scar. n = 3, ***p < 0.001. g Representative dorsal wound photographs in type-2 diabetes C57BL/6mice model at day 0, 3, 6, 9, and 12 after the operation treated with PBS (control), MSC-sEV 200 μg around wounds (scale bar, 5 mm). h Quantification of the wound areas during the wound-healing process. n = 6, ***p < 0.001 at Day 12. i H&E staining of the skin tissue around the wound at day 12 after the operation (horizontal arrows indicated the scar width; scale bar, 1 mm). j Quantification of the scar width and percentage of re-epithelialization around the wound. n = 6, **p < 0.01. k Representative immunofluorescence staining images positive cells of CD31 (green staining) and DAPI in paraffin-embedded sections of diabetic C57BL/6mice dorsal skin injected PBS (control) or MSC-sEV. Red arrows indicate tubes formed around the wound (scale bar, 200 μm). l Quantification of vessels formed around the scar. n = 3, **p < 0.01