EFFECTS OF CO-CR CORROSION PRODUCTS AND CORRESPONDING SEPARATE METAL-IONS ON HUMAN OSTEOBLAST-LIKE CELL-CULTURES

The cytocompatibility of the degradation products of a Co-Cr orthopaed ic alloy was investigated with particular focus on the dose-effect of an electrochemically dissolved alloy extract and of the corresponding separate metal ions on human osteogenic bone marrow derived cells. The extract solution contained 15 ppm of Co and 8 ppm of Cr as analysed b y atomic absorption spectroscopy. Stock salt solutions of CoCl2 . 6H(2 )O, CrCl3 . 6H(2)O and Na2CrO4 at corresponding concentrations were al so prepared. Several dilutions of the above metallic solutions were te sted for a period of 21 days on cells (third subculture) cultured in a lpha-minimal essential medium containing foetal bovine serum and suppl emented with antibiotics, dexamethasone ascorbic acid and beta-glycero phosphate. The osteoblast response to the presence of metal ions was e valuated by several biochemical parameters: cell viability (MTT reduct ion by intracellular enzymes), alkaline phosphatase activity (an osteo blast marker) and protein production (both intracellular and extracell ular). Co-Cr corrosion products showed opposite effects to their respe ctive metal salts only on day 1. With time the different metal solutio ns presented a similar pattern of inhibition. These results suggest th at impaired bone formation in vitro can occur in the presence of Co-Cr corrosion products.