EFFECTS OF AISI 316L CORROSION PRODUCTS IN IN-VITRO BONE-FORMATION

Rat bone marrow cells were cultured in experimental conditions that fa vour the proliferation and differentiation of osteoblastic cells (i.e. , 2.52 x 10(-4) mol l(-1) ascorbic acid, 10(-2) mol l(-1) beta-glycero phosphate and 10(-8) mol l(-1) dexamethasone) in the absence and in th e presence of stainless-steel corrosion products, for a period of 18 d ays. An AISI 316L stainless-steel slurry (SS) was obtained by electroc hemical means and the concentrations of the major metal ions, determin ed by atomic absorption spectrometry, were 8.78 x 10(-3) mol l(-1) of Fe, 4.31 x 10(-3) mol l(-1) of Cr and 2.56 x 10(-3) mol l(-1) of Ni. B one marrow cells were exposed to 0.01, 0.1 and 1% of the SS and at the end of the incubation period, control and treated cultures were evalu ated by histochemical assays for the identification of the presence of alkaline phosphatase and also calcium and phosphate deposition. Cultu res were further observed by scanning electron microscopy. Levels of t otal and ionised calcium and phosphorus in the culture media collected from control and metal exposed cell cultures were also quantified. Hi stochemical staining showed that control cultures presented a strong r eaction for the presence of alkaline phosphatase and exhibited formati on of calcium and phosphates deposits. The presence of 0.01% SS caused no detectable biological effects in these cultures, 0.1% SS impaired osteoblastic behaviour and, 1% SS resulted in cell death. In the absen ce of bone cells, levels of total and ionised calcium and phosphorus i n the control and metal added culture medium were similar throughout t he incubation period. A significant decrease in the levels of ionised calcium and phosphorus were observed in the culture medium of control cultures and also in cultures exposed to 0.01% SS after two weeks of i ncubation, an event related with the formation of mineral calcium phos phate deposits in these cultures. In cultures grown in the presence of 0.1 and 1% SS corrosion products, levels of calcium and phosphorus we re similar to those observed in the absence of cells. Results showed t hat stainless-steel corrosion products above certain concentrations ma y disturb the normal behaviour of osteoblast-like rat bone marrow cell cultures. (C) 1998 Published by Elsevier Science Ltd. All rights rese rved.