Expression of midkine in normal and burn sites of rat skin

Expression of midkine (MK), a retinoic acid-inducible heparin binding growt h factor, was examined immunohistochemically in normal and burn sites of ra t skin. In the normal skin, MK was localized in the epidermis and dermal ap pendages such as hair follicles and sebaceous glands. Mast cells in the sub dermal connective tissue also accumulated MK. After burn injury, MK-positiv e cells began to infiltrate into subdermal connective tissue, and the numbe r of MK-positive cells in the region increased to a maximum at postburn day two and then decreased gradually. Western blotting analysis of both normal and, postburn skin revealed a 30 kDa band reactive with anti-MK antibody; this band was concluded to be a dimer of MK. These findings were discussed from the viewpoint of the possible role of MK in wound healing. (C) 1999 Pu blished by Elsevier Science Ltd and ISBI. All rights reserved.