VLU: venous leg ulcer; PU: pressure ulcer; DFU: diabetic foot ulcer; FTW: full-thickness wound; HPTC: high-purity type I collagen; SD: standard deviation; CD31: cluster of differentiation 31 (endothelial cell marker for capillary density); α-SMA: alpha–smooth muscle actin (marker of fibroblast/myofibroblast activity). Here, PECAM1 is linked to decubitus ulcer.