Quantitative biocompatibility evaluation of nickel-free high-nitrogen stainless steel in vitro/in vivo.
Bottom Line: Endothelialization was greater with HNS than with commercial stainless steel (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.
Affiliation: Biomaterials Unit, Nano-Life Field, International Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, Japan.Show MeSH
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Mentions: It was expected that the inflammatory response of HNS to body would be much lower than that of SUS316L, because in vitro experiments revealed that HNS does not elute the Ni ion. Furthermore, studies have reported that NF-κB-related gene expression is upregulated by Ni ions32,33 and that expression of IL-1β, IL6, and TNF are regulated by NF-κB.34 To investigate NF-κB expression after implantation of HNS in vivo, we evaluated the bioluminescence of the HNS- or SUS316L-implanted area in NF-κB-RE-luc-Xen mice. Figure 4(a) shows the bioluminescent signal of the on or around implanted specimen after implantation of HNS or SUS316L. The metal embedding parts are surrounded by a dotted line. The emission intensity of the HNS was significantly lower than that of the SUS316L. Figure 4(b) shows the intensity of the bioluminescent signal of the implant region. Amounts of bioluminescent signal were shown maximum value after SUS316L implanted site for 3 weeks. In contrast, the emission intensity of the HNS was nearly constant, even after implantation, which is consistent with the fact that the HNS does not elute Ni ions. After 3 weeks, the bioluminescent signal of the HNS (0.28 × 108 ± 0.18 × 108 p/s) was significantly lower (p < 0.05) than that of the SUS316L (1.37 × 108 ± 0.76 × 108 p/s), suggesting that inflammation may be induced by Ni ions derived from SUS316L. After 8 weeks, the bioluminescent signal of SUS316L markedly decreased, and no significant differences were observed between HNS and SUS316L. This finding may reflect encapsulation of SUS316L within the subcutaneous tissue at this time point. The toxic and allergic effect of some metal ions released from used these metals has been previously described.35 Indeed, Ni ion triggers expression of the surface adhesion molecules, such as vascular cell adhesion molecule-1 and intercellular adhesion molecule 1 on endothelial cells36 and induces an increase in NF-κB DNA binding in endothelial cells. These data show that HNS had excellent biocompatibility when compared with SUS316L when used in a coronary artery stent.
Affiliation: Biomaterials Unit, Nano-Life Field, International Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, Japan.