Fig. 4

Effect of DPPSC on epidermal and dermal healing at day 11. a, b Haematoxylin and eosin staining showing the increased epithelial coverage in DPPSC-treated wounds (b) compared to PBS-treated ones (a). Wound boundaries and the length covered by the epidermis are indicated by white arrowheads and black lines, respectively. Presence of red blood cell (RBC) leakage (indicated by asterisk in a, enlarged in inset) can be observed in the PBS-treated condition, while RBCs are contained in blood vessels in DPPSC-treated wounds (b, insets). Scale bars: 200 μm. c, d Haematoxylin and eosin staining showing the increased epithelial thickness in the wound area (wound boundaries are indicated by white arrowheads) in PBS-treated mice (c) compared to DPPSC-treated mice (d). Scale bars: 200 μm. e Quantification of the epithelial thickness in μm. ** p < 0.01, n = 5 mice/group. f, g Sirius Red staining visualised by bright field microscopy of the central part of wounds treated with PBS (f) or DPPSC (g) for the analysis of total collagen in the wound matrix. Scale bars: 100 μm. h Quantification of the total collagen present in the wound centre and margins of mice treated with PBS or DPPSC. **p < 0.01, n = 5 mice/group. i, j Sirius Red staining of the same sections of wounds treated with PBS (i) or DPPSC (j) as in f, g visualised by polarised light microscopy for the analysis of organised (red birefringent) collagen in the wound matrix. Scale bars: 100 μm. k Quantification of the organised collagen present in the wound centre and margins of mice treated with PBS or DPPSC. **p < 0.01, n = 5 mice/group. l, m Immunofluorescence analysis for collagen type III (COL3; in green) in wounds treated with PBS (l) or DPPSC (m). n Quantification of the percentage of wound area positive for COL3 I in the wound centre of mice treated with PBS or DPPSC. *p < 0.05, n = 5 mice/group. o, p Immunofluorescence analysis for collagen type I (COL1; in red) in wounds treated with PBS (o) or DPPSC (p). q Quantification of the percentage of wound area positive for COL1 in the wound centre of mice treated with PBS or DPPSC. *p < 0.05, n = 5 mice/group. For l, m, o, p, nuclei are counterstained with DAPI (blue); scale bars: 100 μm. Two-tailed Student’s t test was used for e, n, q; one-way ANOVA test was used for h, k; results are displayed as mean ± s.e.m