Exposure to high levels of magnesium disrupts bone mineralization in vitro and in vivo

Wenxiang Chu; Tao Li; Gaozhi Jia; Yongyun Chang; Zhiqing Liu; Jia Pei; Degang Yu; Zanjing Zhai

doi:10.21037/atm-20-1921

Exposure to high levels of magnesium disrupts bone mineralization in vitro and in vivo

Ann Transl Med. 2020 Nov;8(21):1419. doi: 10.21037/atm-20-1921.

Authors

Wenxiang Chu^{1

2}, Tao Li^{1

3}, Gaozhi Jia⁴, Yongyun Chang¹, Zhiqing Liu¹, Jia Pei⁴, Degang Yu¹, Zanjing Zhai¹

Affiliations

¹ Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
² Department of Orthopedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China.
³ Department of Orthopaedics, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
⁴ National Engineering Research Center of Light Alloy Net Forming & State Key Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.

Abstract

Background: The removal of permanent internal fixation devices by secondary surgery could be avoided if these devices were made of degradable magnesium and magnesium alloys. Before such implants can be used clinically, however, the biological effect of magnesium exposure on surrounding bone must be evaluated. Previous studies have focused on bone formation; few have examined the effects of magnesium on the bone quality that affect many biomechanical properties.

Methods: Using bone quality parameters, we analyzed in vivo changes in bone properties and biomechanics after exposure to locally high levels of magnesium.

Results: Local bone mineralization was significantly disrupted following exposure to a porous rod of pure magnesium. Normal crystal formation and crystallinity were inhibited and the mineral-to-matrix ratio decreased. These results were consistent with those of in vitro experiments, in which high levels of magnesium inhibited mineral deposition by mesenchymal stem cells (MSCs) but increased alkaline phosphatase (ALP) expression. The same mineralization inhibition was observed around magnesium implants via micro-computerized tomography (micro-CT) and von Kossa staining. Such reduced bone quality around degrading magnesium rods could negatively impact bone biomechanics.

Conclusions: This study showed that exposure to the local high magnesium levels that arise from rapidly degrading magnesium devices may significantly disrupt bone mineralization and negatively impact bone biomechanics.

Keywords: Magnesium; bone quality; degradable implants; mineralization.