EFFECTS OF METAL-IONS ON OSTEOBLAST-LIKE CELL-METABOLISM AND DIFFERENTIATION

The objective of this study was to evaluate the effects of metal ions, which may be released from orthopedic or dental implants, on osteobla st metabolism and differentiation. ROS 17/2.8 cells were cultured in F -12 medium for 7 days. Then Al+3, Co+2, Cr+3, Ni+2, Ti+4, and V+3 were added at concentrations less than their cytotoxic concentrations. Aft er 3 days, DNA synthesis, succinate dehydrogenase activity, alkaline p hosphatase (ALP) activity, and culture calcification were assessed. No rthern blots were performed for ALP, osteocalcin (OCN), and osteoponti n (OPN) mRNA transcription. The data indicated that Cr+3 and Al+3 had few inhibitory effects on ROS cell metabolism below their cytotoxic co ncentrations, Ni+2, Co+2, Ti+4, and V+3 affected all these parameters of ROS cell metabolism at concentrations below cytotoxic levels. For R NA analysis, Al+3 significantly suppressed the expression of ALP, OCN, and OPN at both cytotoxic and noncytoxic concentrations. Co+2 specifi cally suppressed ALP expression at cytotoxic concentrations. Cr+3 and Ni+2 inhibited OCN, OPN, and ALP gene expression only at cytotoxic con centrations. For Ti+4 and V+3 ions, gene expression at cytotoxic level s was not significantly affected as compared with the effects at noncy totoxic level. These results show that metal ions may alter osteoblast behavior even at subtoxic concentrations, but do not always affect th e expression of all genes similarly. (C) 1997 John Wiley & Sons, Inc.