Effect of La3+ and Mg2+ combined system on bioactivity and osteogenesis of bioinspired La-doped magnesium phosphate composites prepared utilizing the precursor method

Abstract

Lanthanum (La) compounds have attracted much attention because of low toxicity and biocompatibility. In this study, a series of La-doped magnesium phosphate composites bone repair materials (LMPCs) were prepared by the precursor method, in which the molar ratio of lanthanum was 1%, 3% and 5%, respectively. The results of X-ray powder diffraction, scanning electron microscope and compressive strength test show that La-doped magnesium phosphates (LMPs) synthesized by the precursor method have uniform particle distribution, high purity and excellent degradability. In vitro research results show that LMPCs exhibited reliable biosafety and excellent bioactivity. The introduction of lanthanum enhances the antibacterial activity of Escherichia coli and Staphylococcus aureus of the composite. Furthermore, the combined system of released La3+ and Mg2+ is more conducive to promoting the proliferation of mesenchymal stromal cells (MSC) and angiogenesis of human umbilical vein endothelial cells (HUVECs) when the content of lanthanum is 3% (referred to as LMPC-2). By up-regulating the expression of alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2), LMPC-2 is prominent in promoting osteogenic differentiation, and mineralized calcium deposition in vitro. Moreover, the results of micro-CT, H&E and Masson staining confirmed the beneficial effect of the combined system of La3+ and Mg2+ on the repair of rat skull defects in vivo. These achievements will provide new strategies for improving the biological activity of LMPCs and provide reference value for bone repairing in the clinic.

Keywords

• La-doped magnesium phosphate composites
• Antibacterial activity
• Angiogenesis
• Osteogenesis
• La3+ and Mg2+ combined system