a Harvested tissues from 1-month-old wounds were cross-sectioned and stained with Masson’s trichrome dyes before light microscopy imaging. Amounts of granulation tissue were quantified as cross-section areas from high-resolution digital images. Representative images show impaired granulation tissue formation, which can be found in wounds from controls treatment groups, and mature granulation tissue in wounds from PDGFB MSC and VEGFA MSC treatment groups. Epi epithelium, GT granulation tissue, UW unwounded skin. b Box and whiskers plots show distributions of granulation tissue areas measured from cross-sections of individual wounds from PBS and hMSC controls, PDGFB MSC, and VEGFA MSC treatment groups (n = 10, 8, 8, and 10 wounds, respectively). Minima and maxima are bounded by whiskers, lower bounds, centers, and upper bound of boxes represent the 25th, 50th, and 75th percentiles, respectively. Differences of means were tested by ordinary one-way ANOVA and p-values were computed using Tukey’s multiple comparisons test. Asterisks indicate p-values (*p < 0.05; **p < 0.01, n.s.: p > 0.05). c (Left panel) Harvested tissues from one-month-old wounds were cross-sectioned (x-section) and stained with anti-mouse CD31 antibody. Stained blood vessels were detected from digital staining images using ImageJ software. Blood vessel density was calculated from whole granulation tissues. (Right panel) Representative blood vessel images from controls, PDGFB MSC, and VEGFA MSC treatment groups are shown. d Box and whiskers plots show distributions of blood vessel densities measured from cross-sections of individual wounds from PBS and hMSC controls, PDGFB MSC, and VEGFA MSC treatment groups (n = 6, 6, 7, and 8 wounds, respectively). Minima and maxima are bounded by whiskers, lower bounds, centers, and upper bound of boxes represent the 25th, 50th, and 75th percentiles, respectively. Differences of means were indicated by ordinary one-way ANOVA and p-values were computed using Tukey’s multiple comparisons test. Asterisks indicate p-values (**p < 0.01; ***p < 0.001, n.s.: p > 0.05). Source data are available in the Source data file.