Pathological changes in hypertrophic scar tissue at different stages were shown by immunofluorescence staining for CD31 and α-SMA.

Although few microvessels and fibroblasts were observed in NS, more were observed in PSs; however, most of the microvessels were partially or completely occluded in RSs, and the RSs exhibited fewer fibroblasts. In MSs, the numbers of microvessels and cells were comparable to those in NS. a, b, c, and d represent NS, PS, RS and MS samples, respectively. Scale bar: 30 μm. The green staining represents ECs, the red staining represents smooth muscle cells, and the blue staining represents fibroblasts.