Anti α smooth muscle actin clone 1a4

All specimens were stained with hematoxylin and eosin (H&E), Elastica van Gieson, von Kossa, and Masson‐Trichrome (CoverStainer for H&E and ArtisanLink for other stains; Dako). In addition, immunohistochemical staining was performed using the following antibodies: anti‐CD68 (Clone KP1; Dako), anti‐CD10 (Clone 56C6; Novocastra), anti‐CD31 (Clone JC70A; Dako), and anti‐α‐smooth muscle actin (Clone 1A4; Dako). Stained slides were scanned using Aperio Scan Scope and imaged with Aperio Image Scope (Leica Biosystems). H&E‐stained slides were prepared to obtain a general overview over the tissue and to evaluate the thickness of the epidermis and dermis and re‐epithelialization of the wound bed. Von Kossa‐stained slides were used to evaluate the presence of calcification. Elastica van Gieson‐stained slides were used to evaluate the presence of elastic fibres and collagen. Masson trichrome staining was performed for the histological visualisation of collagen and identification of collagen subtypes. The amount of mature collagen within the wound area was assessed in a semi‐quantitatively manner by scoring for a substantial amount of collagen, a moderate amount of collagen, a low amount of collagen, or no collagen. The biopsies were analysed in a paired fashion: PCT‐treated wounds were compared to SoC‐treated wounds at V9 and to initial skin biopsies taken at V2 (Figure S2).