Exploring the Osteogenic Potential of Zinc-Doped Magnesium Phosphate Cement (ZMPC): A Novel Material for Orthopedic Bone Defect Repair

Abstract

In orthopedics, the repair of bone defects remains challenging. In previous research reports, magnesium phosphate cements (MPCs) were widely used because of their excellent mechanical properties, which have been widely used in the field of orthopedic medicine. We built a new k-struvite (MPC) cement obtained from zinc oxide (ZnO) and assessed its osteogenic properties. Zinc-doped magnesium phosphate cement (ZMPC) is a novel material with good biocompatibility and degradability. This article summarizes the preparation method, physicochemical properties, and biological properties of ZMPC through research on this material. The results show that ZMPC has the same strength and toughness (25.3 ± 1.73 MPa to 20.18 ± 2.11 MPa), that meet the requirements of bone repair. Furthermore, the material can gradually degrade (12.27% ± 1.11% in 28 days) and promote osteogenic differentiation (relative protein expression level increased 2-3 times) of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. In addition, in vivo confirmation revealed increased bone regeneration in a rat calvarial defect model compared with MPC alone. Therefore, ZMPC has broad application prospects and is expected to be an important repair material in the field of orthopedic medicine.

Keywords: bone defect; bone repair; osteogenic differentiation; rat bone marrow mesenchymal stem cells; zinc-doped magnesium phosphate cement.

Figure 1

Image of rat skull defect.

Figure 2

(A–H) SEM images of the surface morphology of different cements.

Figure 3

XRD patterns (A) and Raman (B) of different composites.

Figure 4

(A) Compressive strength. (B) Weight loss. (C) Mg²⁺ released into medium. (D) pH of immersion medium.

Figure 5

(A–E) Live/dead assays of BMSCs. (F) Quantitative analysis of Live/dead assays. (G) CCK8 analysis of BMSCs at day 1, 3 and 5, respectively. * p < 0.05, *** p < 0.001, **** p < 0.0001.

Figure 6

(A,B) Osteogenic differentiation on the samples. The osteogenic gene markers BMP2, OCN RUNX2 and ALP were determined using quantitative PCR and western blotting. (C,D) Quantitative analysis of western blotting and fluorescence intensity. (E) Immunofluorescence images stained with OPN (red) and ALP (green). The scale is 50 μm. * p < 0.05, ** p < 0.01, *** p < 0.001,**** p < 0.0001.

Figure 7

(A) ARS staining of BMSCs for 21 days. (B) ALP staining of BMSCs for 14 days. (C,D) Quantitative analysis by imageJ, * p < 0.05, ** p < 0.01.

Figure 8

(A,B) Micro-CT reconstruction of calvarial defects after 4 and 12 weeks. (C–E) Quantitative analysis of BV/TV, Tb.N, Tb.th and Tb.Sp, * p < 0.05.

Figure 9

H&E and Masson staining of non-decalcified rat cranial sections of regenerated bone observed at 4 and 12 weeks following implantation. (A) MPC (B) MPC/Zn (5%).