IN-VITRO BIOMINERALIZATION BY OSTEOBLAST-LIKE CELLS - I - RETARDATIONOF TISSUE MINERALIZATION BY METAL-SALTS

The cytocompatibility of stainless steel 316L (SS 316L) corrosion prod ucts was investigated with particular focus on the dose- and time-effe ct of electrochemically dissolved SS and the corresponding separate me tal ions on osteogenic bone marrow derived cells. Type AISI 316L stain less steel (Fe 63.9%, Cr 18.0%, Ni 12.5%, Ma 2.8%, Si 1.2%, Mn 1.6% an d C 0.025%, weight for weight) was anodically dissolved in Hank's Bala nced Salt Solution (HBSS) and diluted to the following concentrations: 500 mu g ml(-1) of Fe, 122 mu g ml(-1) of Cr and 101 mu g ml(-1) of N i, as estimated by atomic absorption spectrometry. Similarly, salt sol utions containing 500 mu g ml(-1) of Fe (FeCl3 . 6H(2)O), 122 mu g ml( -1) of Cr (CrCl3 . 6H(2)O) or 101 mu g ml(-1) of Ni (NiNO3) were prepa red. All solutions were diluted 1:10(3), 1:10(4) and 1:10(5) and their effects on cell proliferation and function of rabbit bone marrow cell s were studied up to 28 days of culture. Bone marrow cells (second sub culture) were cultured in alpha-Minimal Essential Medium (alpha-MEM) s upplemented with 10% fetal bovine serum 10(-8) mol l(-1) dexamethasone , 2.52 x 10(-4) mol l(-1) ascorbic acid and 10(-2) mol l(-1) beta-glyc erophosphate. The osteoblast response to the presence of metal ions wa s evaluated by biochemical assays (enzymatic reduction of MTT for eval uation of cell viability/proliferation, and estimation of alkaline pho sphatase (ALP) activity) and histochemical assays (identification of A LP positive cells and calcium and phosphates deposits). Results sugges t a decrease in the expression of the osteoblast phenotype in the pres ence of ion and alloy solutions. Stainless steel corrosion products el icited slight effects but the corresponding metal ions produced pronou nced effects on the osteoblast phenotype, namely an alteration in the levels and temporal expression of ALP and lower and retarded tissue mi neralization ability. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.