Preparation of lithium-containing magnesium phosphate-based composite ceramics having high compressive strength, osteostimulation and proangiogenic effects.

Fairly high concentrations of magnesium and lithium are conducive to improving the osteogenic and angiogenic capacities. In the current study, lithium-containing magnesium phosphate-based ceramics (AMP/LMPGs) were prepared from amorphous magnesium phosphate (AMP) at a low sintering temperature (650 °C), and the lithium/magnesium-containing phosphate glasses (LMPGs) were utilized as sintering additives. During the sintering procedure of AMP/LMPGs, the AMP reacted with LMPGs, producing new compounds. The AMP/LMPGs displayed nano-size grains and plentiful micropores. The addition of LMPGs noticeably increased the porosity as well as compressive strength of the AMP/LMPGs ceramics. The AMP/LMPGs sustainedly released Mg, P and Li ions, forming Mg-rich ionic microenvironment, which ameliorated cellular proliferation, osteogenic differentiation and proangiogenic capacities. The AMP/LMPGs ceramics with considerably high compressive strength, osteostimulation and proangiogenic effects were expected to efficiently regenerate the bone defects.

Preparation and characterization of novel lithium magnesium phosphate bioceramic scaffolds facilitating bone generation.

Both magnesium and lithium are able to stimulate osteogenic and angiogenic activities. In this study, lithium magnesium phosphate (Li0.5Mg2.75(PO4)2, Li1Mg2.5(PO4)2 and Li2Mg2(PO4)2) biomaterials were synthesized by a solid-state reaction method, and their bioceramic blocks and scaffolds were fabricated by compression molding and 3D printing, respectively. The results indicated that the lithium magnesium phosphates consisted of the Mg3(PO4)2 phase and/or LiMgPO4 phase. Compared with the lithium-free Mg3(PO4)2 bioceramics, the lithium magnesium phosphate bioceramics showed a lower porosity and consequently a higher compressive strength, and stimulated in vitro cellular proliferation, osteogenic differentiation and proangiogenic activity. In vivo results manifested that the Li2Mg2(PO4)2 bioceramic scaffolds efficiently promoted bone regeneration of critical-size calvarial defects in rats. Benefiting from the high compressive strength and capacity of stimulating osteogenesis and angiogenesis, the Li2Mg2(PO4)2 bioceramic scaffolds are considered promising for efficiently repairing the bone defects.

Novel Extrusion-Microdrilling Approach to Fabricate Calcium Phosphate-Based Bioceramic Scaffolds Enabling Fast Bone Regeneration.

This study proposes a novel approach, termed extrusion-microdrilling, to fabricate three-dimensional (3D) interconnected bioceramic scaffolds with channel-like macropores for bone regeneration. The extrusion-microdrilling method is characterized by ease of use, high efficiency, structural flexibility, and precision. The 3D interconnected ß-tricalcium phosphate bioceramic (EM-TCP) scaffolds prepared by this method showed channel-like square macropores (∼650 µm) by extrusion and channel-like round macropores (∼570 µm) by microdrilling as well as copious micropores. By incorporating a strontium-containing phosphate-based glass (SrPG), the obtained calcium phosphate-based bioceramic (EM-TCP/SrPG) scaffolds had noticeably higher compressive strength, lower porosity, and smaller macropore size, tremendously enhanced in vitro proliferation and osteogenic differentiation of mouse bone marrow stromal cells, and suppressed in vitro osteoclastic activities of RAW264.7 cells, as compared with the EM-TCP scaffolds. In vivo assessment results indicated that at postoperative week 6, new vessels and a large percentage of new bone tissues (24-25%) were formed throughout the interconnected macropores of EM-TCP and EM-TCP/SrPG, which were implanted in the femoral defects of rabbits; the bone formation of the EM-TCP group was comparable to that of the EM-TCP/SrPG group. At 12 weeks postimplantation, the bone formation percentage of EM-TCP was slightly reduced, while that of EM-TCP/SrPG with a slower degradation rate was pronouncedly increased. This work provides a new strategy to fabricate interconnected bioceramic scaffolds allowing for fast bone regeneration, and the EM-TCP/SrPG scaffolds are promising for efficiently repairing bone defects.