Particles Generated from Degrading Magnesium Implants Induce Bone Resorption

Abstract Background Magnesium (Mg) is regarded as “revolutionary orthopedic material” due to its excellent properties. In the frontier of clinical translation of biodegradable Mg, most researchers have found cavities between bone tissue and Mg-based implants which limit the use of Mg. These cavities were regarded to be formed due to H2 gas generated from the rapid degradation of Mg. However, this explanation still lacks direct evidence. In this study, we come up with a new hypothesis aim to explain the cavities formation around the Mg-based implants. Methods The slightly soluble degradation particles (DPs) of high purity magnesium (HP-Mg) were prepared by electrochemical method. The effects of DPs on osteoclasts formation, polarization, and osteoclast bone resorption in vitro and in vivo were investigated. Results The results revealed that DPs could induce osteoclast formation. The DPs promoted the activation of both NF-κB and MAPK signaling pathways and the expression of osteoclast-specific genes and proteins were upregulated. At the same time, DPs also could accelerate calvarial bone resorption of mice. Conclusions These results confirmed that the presence of DPs could induce bone resorption both in vitro and in vivo, discovering a new explanation for cavities around Mg-based implants. This discovery inspires new solutions to solve the cavity problem.