[Histological study of multinucleated giant cells in bone grafting]

The purpose of this study was to determine histochemically the characteristics of elicited multinucleated giant cells adhering artificial graft materials. As artificial graft materials, resorbable ceramic beta-tricalcium phosphate, non-soluble porous hydroxyapatite and non-soluble non-porous hydroxyapatite were examined, with devitalized bone particles serving as the control. Both test and control graft materials were implanted subcutaneously in rats and mice. Acid phosphatase and tartrate resistant acid phosphatase were positive in elicited multinucleated giant cells adhering to both artificial graft materials and devitalized bone particles. Elicited multinucleated giant cells elicited adhering to sutures were negative. The number of multinucleated giant cells positive to non-specific esterase was minimum except in areas they adhered to sutures. Elicited multinucleated giant cells adhering to graft materials showed enzyme activities similar to those of osteoclasts, and it was suggested that artificial graft materials may be absorbed by osteoclasts.