Elevated expression of pleiotrophin in human hypertrophic scars

Hypertrophic scar (HS) is a cutaneous fibrotic disorder characterized by persistent inflammation, excessive proliferation of fibroblasts, and abundant accumulation of extracellular matrix (ECM) proteins. Pleiotrophin (PTN) is a highly conserved and secreted ECM-associated protein that belongs to a novel family of heparin-binding cytokines with multiple biological functions. The aim of this study was to detect and compare the expression and localization of PTN in HS tissues and normal skin tissues. Surgically removed HS tissue samples and site-matched normal skin specimens were obtained from 18 patients during the scar excision and reconstructive surgery. Semi-quantitative RT-PCR, Western blot analysis and immunohistochemistry were used to determine PTN gene expression and localization in skin tissues. Compared with the normal skin tissues, PTN was highly expressed at both mRNA and protein levels in HS tissues (P < 0.01). In immunohistochemical staining, PTN protein was localized in the cells of both epidermis and dermis in skin tissues, and there were increased staining intensity of PTN in HS tissues than in normal skin samples. In conclusion, elevated expression of PTN is likely to be involved in the pathogenesis of HS. Further studies are still required to elucidate the exact role of PTN in HS formation.