Magnesium Calcium Phosphate Cement Incorporating Citrate for Vascularized Bone Regeneration.

The development of bioactive bone cement is still a challenge for vascularized bone regeneration. Citrate participated in multiple biological processes, such as energy metabolism, osteogenesis, and angiogenesis. However, it is difficult to obtain a thorough and comprehensive understanding on osteogenic effects of exogenous citrate from different experimental conditions and treatment methods. In this study, by using a magnesium calcium phosphate cement (MCPC) matrix, we investigated the dual effect of exogenous citrate on osteogenesis and angiogenesis. Our studies show that citrate elevates the osteogenic function of osteoblasts under low doses and the angiogenic function of vascular endothelial cells under a broader dose range. These findings furnish a new strategy for regulating angiogenesis and osteogenic differentiation by administration of citrate in MCPC, driving the development of bioactive bone repair materials.

Magnesium phosphate based cement with improved setting, strength and cytocompatibility properties by adding Ca(H2PO4)2·H2O and citric acid.

Inorganic phosphate cements have become prevalent as bone filling materials in clinical applications, owing to beneficial properties such as self-setting, biodegradability and osteoconductivity. However, the further development of phosphate cements with higher strength and improved cytocompatibility is expected. In this paper, we reported the preparation of a novel magnesium phosphate based cement (MPBC), which has similar compositions with magnesium phosphate cement (MPC) but Ca(H2PO4)2·H2O and citric acid were additionally added to modulate the performance. The physicochemical and biological properties of MPBC were investigated, the influences of the added Ca(H2PO4)2·H2O and citric acid on the performances of MPBC were analyzed, and the differences of performance between MPBC and MPC were discussed. Experimental results show that the setting time and compressive strength of MPBC were effectively enhanced by the addition of citric acid. In vitro biological degradation indicates that about 15 wt% of MPBC was reduced in 4 weeks. Compared with MPC, MPBC has weaker alkalinity and less dissolution of phosphate, leading to better suitability for cell proliferation and adhesion. These results suggest that as a bone filling material, MPBC shows better performance than MPC in many key indicators and has promising application prospects.

Citric acid enhances the physical properties, cytocompatibility and osteogenesis of magnesium calcium phosphate cement.

In recent years, the magnesium phosphate cements showed impressive advantages for their setting property, mechanical strength, and resorption rate in laboratory investigation. While it remained a big challenge to develop the magnesium phosphate cements with ideal self-setting properties, sufficient mechanical strength, excellent biocompatibility, and osteoinductivity for clinical application. In our work, we prepared the magnesium calcium phosphate cement (MCPC) using the MgO, KH2P2O4, and Ca(H2PO4)2 particles with the citric acid added. The citric acid was adopted to modify the setting time and compressive strength of the MCPC, which were investigated by the X-ray diffractometer and scanning electron microscopy. The cytocompatibility and osteoinductivity of the modified cements were evaluated by the MC3T3-E1 cells proliferation and morphology, alkaline phosphatase assay, alizarin red staining and western blot assay. The results demonstrated that the citric acid modified MCPC was featured of satisfactory setting time, ideal mechanical strength, good cytocompatibility and osteoinductivity, indicating its potential application for bone regeneration.