The Effect of Metal Materials on Heat Shock Protein 70B’ Gene Expression

To avoid the toxic effect of released nickel ions and compounds from conventional stainless steels, nickel-free austenitic stainless steels have been developed. We previously established a new manufacturing process to produce nickel-free austenitic stainless steel that involves nitrogen adsorption treatment. Although the cytocompatibility of nickelfree austenitic stainless steel produced using this method has been evaluated using two viability assay, molecular level analysis, such as gene expression analysis, has not been previously performed. In the present study, the cytotoxicity of our nickel-free austenitic stainless steel, as well as of commercially available metal materials, was evaluated by analysis of heat shock protein 70B’ (HSP70B’) gene expression as a stress response marker. Furthermore, to investigate the effect of metal materials on cytotoxicity, HSP70B’ gene expression was quantified using human osteoblast-like SaOS-2 cells, human monocyte THP-1 cells and the mouse macrophage cell line J774A.1. We found no significant differences in HSP70B’ expression among the various metal materials, including the nickel-free austenitic stainless steel, indicating that the nickel-free austenitic stainless steel produced using our nitrogen adsorption method has the same cytocompatibility as commercially available metal materials.