The influence of yttrium and manganese additions on the degradation and biocompatibility of magnesium-zinc-based alloys: In vitro and in vivo studies

The repair and regeneration of bone defects are highly challenging orthopedic problems. Recently, Mg-based implants have gained popularity due to their unique biodegradation and elastic modulus similar to that of human bone. The aim of our study is to develop a magnesium alloy with a controllable degradation that can closely match bone tissue to help injuries heal in vivo and avoid cytotoxicity caused by a sudden increase in ion concentration. In this study, we prepared and modified Mg-3 Zn, Mg-3Zn-1Y, and Mg-2Zn-1Mn by hot extrusion, and used Mg-2.5Y-2.5Nd was as a control. We then investigated the effect of additions of Y and Mn on alloys' properties. Our results show that Mn and Y can improve not only compression strength but also corrosion resistance. The alloy Mg-2Zn-1Mn demonstrated good cytocompatibility in vitro, and for this reason we selected it for implantation in vivo. The degraded Mg-2Zn-1Mn implanted a bone defect area did not cause obvious rejection and inflammatory reaction, and the degradation products left no signs of damage to the heart, liver, kidney, or brain. Furthermore, we find that Mg-2Zn-1Mn can promote an osteoinductive response in vivo and the formation of bone regeneration.