Immunohistochemical staining

Sample tissues from each group (hypertrophic scar and normal skin) were enclosed with pathological filter paper, fixed immediately with 10% buffered formalin at room temperature overnight, processed through graded alcohols and xylene, embedded in paraffin, and sectioned at 5-µm thickness (3 replicates for each specimen). Mast cells and mast cell chymase were immunohistochemically stained using polyclonal rabbit anti-human CD117 (1:500; cat no. LS-{"type":"entrez-nucleotide","attrs":{"text":"C20514","term_id":"4714548","term_text":"C20514"}}C20514; c-Kit; LifeSpan BioSciences, Inc., Seattle, WA, USA) antibody and polyclonal mouse anti-chymase antibody (1:500; cat no. kl086Bo01; Gene Company Ltd., Shanghai, China), respectively, and incubated at 4°C overnight. Samples were subsequently incubated with horseradish peroxidase-conjugated anti-rabbit secondary antibody (1:1,000; cat no. GK500705; Dako; Agilent Technologies, Inc., Santa Clara, CA, USA) at 37°C for 30 min. Positive expression of CD117 and chymase was indicated by brown staining of cell membrane and cytoplasm. As a negative control, PBS was used instead of primary antibodies.