Platelet-derived growth factor in middle ear cholesteatoma

Platelet-derived growth factor (PDGF) was localized in human middle ear cholesteatoma tissue by an immunoperoxidase technique using rabbit anti-human PDGF IgG. PDGF was found mainly in basal cells and in granulation tissue, and especially involved monocytes and fibroblast-like cells. The external ear canal epithelium was not significantly stained by anti-human PDGF. Findings demonstrate that the presence of PDGF in cholesteatoma is in response to inflammation and wound healing in the middle ear. PDGF in vitro was found to stimulate protein synthesis and cellular terminal differentiation of basal keratinocytes. PDGF also stimulated monocytes to form multinucleated osteoclast-like cells. These multinucleated cells, in turn, induced the resorption of devitalized bovine bone. This bone resorption was seen in co-cultures of osteoblasts and multinucleated osteoclast-like cells in the presence of PDGF, suggesting that cell-to-cell interaction plays a role in bone resorption. The present study suggests that PDGF takes part in the clinical development and the destructive effect of cholesteatoma.