Fig. 6.

UCMSCs-exo/eNOS promote angiogenesis in chronic wounds of diabetic mice. I: Treatment with PBS. II: Treatment with UCMSCs-exo. III: Treatment with UCMSCs-exo/eNOS. a CD31 immunofluorescence staining of neovascularization in the wounds of different groups at postoperative day 7. Scale bar: 100 μm. b Quantitative immunofluorescence analysis of CD31 in a (n = 6 in each group, two-tailed Student’s t-test). c CD31 immunofluorescence staining of neovascularization in the wounds of different groups on postoperative day 21. Scale bar: 100 μm. d Quantitative immunofluorescence analysis of CD31 in c (n = 6 in each group, two-tailed Student’s t-test). e α-SMA immunofluorescence staining of mature blood vessels from the wounds of different groups on postoperative day 21. Scale bar: 100 μm. f Quantitative immunofluorescence analysis of α-SMA (n = 6 in I group, n = 5 in II group and n = 6 in III group, Mann–Whitney U test). Data represent means ± SD. *p < 0.05, **p < 0.01, ***p < 0.001 vs. PBS group; ^#p < 0.05, ^##p < 0.01, ^###p < 0.001 vs. UCMSCs-exo group