INTERACTIONS OF ORTHOPEDIC METALS WITH AN IMMORTALIZED RAT OSTEOBLASTCELL-LINE

The toxicity of nickel, chromium (III) and (VI), vanadium and aluminiu m was compared in an immortalized neonatal rat osteoblast cell line us ing the MTT assay and a novel index of cytoxicity, alkaline phosphatas e (ALP) activity. Where toxicity was observed, ALP was a consistently more sensitive detection method than the MTT assay. The toxicity of th e metals increased in the order aluminium < chromium (III) < vanadium < nickel < chromium (VI). alpha-Tocopherol partially prevented nickel- induced toxicity (as assessed by ALP activity), whereas ascorbic acid had no protective effect. Chromium (VI) was more toxic than (III), wit h significant toxicity observed at 0.5 mu M. It is thought that Cr (II I) cannot readily penetrate the cell membrane and this may account for the lower toxicity. Aluminium had a stimulatory effect on cell growth at low concentrations (0.5 mu M). The combination of immortalized rat osteoblasts and the ALP activity test provides a powerful tool for in vitro testing of orthopaedic materials. (C) 1996 Elsevier Science Lim ited