Quantitative biocompatibility evaluation of nickel-free high-nitrogen stainless steel in vitro/in vivo

Coronary stents must not provoke an inflammatory response; however, some kinds of ions that are released from biometals induce biological reaction. In the present study, we quantitatively evaluated biological reaction of nickel-free high-nitrogen stainless steel (HNS) by endothelial cell culture, and a bioimaging system using NF-κB/luciferase transgenic mice to confirm the potential of HNS for the application of coronary stent. Endothelialization was greater with HNS than with commercial stainless steel (SUS316L). In vivo inflammatory response of HNS was lower than that of SUS316L. These differences may be related to the amounts of nickel ion eluted from the stents, as HNS did not elute nickel ion. These data suggest that HNS may be useful as a material for coronary artery stents.