EFFECT OF METAL-IONS ON THE FORMATION AND FUNCTION OF OSTEOCLASTIC CELLS IN-VITRO

To determine if metal ions play a contributing role in loosening of or thopedic implants, the present work investigated whether sublethal con centrations of ions affect the formation and function of osteoclasts i n vitro. Rat bone marrow cells were cultured on slices of devitalized bone and in the presence of ions associated with Co-Cr-Mo and Ti-6Al-4 V alloys for up to four weeks. Cultures were assayed for total intrace llular protein, used as measure of cell growth, and resorption activit y of osteoclastic cells derived from hematopoietic stem cells was quan tified using image analysis. Although Co2+ caused delayed toxicity not previously observed during short-term experiments, none of the other ions affected cell proliferation, indicating that the chosen concentra tions were sublethal. In general, exposure of bone marrow cultures tc ions caused either a decrease or no change in the total area of bone r esorption. A decrease in the number of resorption pits formed by osteo clastic cells was primarily responsible for the decrease in total amou nt of resorption. Therefore, even though cells continued to grow over the entire culture period, less osteoclastic activity was observed. Fi ndings indicate that if metal ions play a role in periprosthetic patho logy, they may contribute to implant failure by impairing bone repair while allowing fibrous tissue formation following debris-induced osteo lysis. (C) 1997 John Wiley & Sons, Inc.