Tissue localization of β receptors for platelet-derived growth factor and platelet-derived growth factor B chain during wound repair in humans

Abstract

The expression and localization of PDGF βreceptors and PDGF-AB/BB in human healing wounds was evaluated by immunohistochemical techniques and in situ hybridization. Expression of PDGF β receptor protein and PDGF-AB/BB were analyzed in wound margin biopsies using the PDGFR-B2 and PDGF 007 antibodies. PDGF β receptor expression was minor in normal skin. An increased expression of PDGF β receptor protein was prominent in vessels in the proliferating tissue zone in wounds as early as 1 d after surgery and was apparent ≤ 4 wk after surgery. There was also a concordant increase in PDGF β receptor mRNA detected by in situ hybridization. PDGF-AB/ BB was present in healing wounds as well as in normal skin. In normal skin, expression of PDGF-AB/BB was confined to peripheral nerve fibers and to solitary cells of the epidermis and of the superficial dermis. In wounds, infiltrating mononuclear cells also stained for PDGF-AB/BB. To identify cell types expressing PDGF AB/BB and PDGF β receptors, respectively, we performed double immunofluorescence stainings. PDGF β receptors were expressed by vascular smooth muscle cells and cells in capillary walls; the receptor protein could not be detected in neurofilament containing structures, T lymphocytes, or CD68 expressing macrophages. PDGF-AB/BB colocalized with neurofilaments, it was present in Langerhans cells of the epidermis and in HLA-DR positive cells located in the epidermal/dermal junction area. Of the macrophages infiltrating the wound, 43±18% stained positively for PDGF AB/BB. Since PDGF-AB/BB and PDGF β receptors are expressed in the healing wound, two essential prerequisites for a role of PDGF in wound healing are fulfilled.