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 β-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.

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Gallium (Ga) ions have been clinically approved for treating the diseases caused by the excessive bone resorption through the systemic administration. Nevertheless, little attention has been given to the Ga‐containing biomaterials for repairing bone defects under the pathological condition of excessive bone resorption. In the current study, for the first time the Ga‐containing phosphate glasses (GPGs) were introduced to modify the honeycomb β‐tricalcium phosphate (β‐TCP) bioceramic scaffolds, which were prepared by an extrusion method. The results indicated that the scaffolds were characterized by uniform pore structure and channel‐like macropores. The addition of GPGs promoted densification of strut of scaffolds by achieving liquid‐sintering of β‐TCP, thereby tremendously increasing the compressive strength. The ions released from scaffolds pronouncedly inhibited osteoclastogenesis‐related gene expressions and multinuclearity of RAW264.7 murine monocyte cells, as well as expressions of early osteogenic makers of mouse bone mesenchymal stem cells (mBMSCs). However, the scaffolds with lower amount of Ga increased cell proliferation and upregulated expression of late osteogenic maker of mBMSCs. This study offers a novel approach to modify the bioceramic scaffolds for bone regeneration under the condition of accelerated bone resorption. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1314–1323, 2019.

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In this study, β‐tricalcium phosphate/phosphate‐based glass (β‐TCP/PG) composite spheres were prepared by an extrusion‐spheronization method featuring high production and fine control of sphere size. Subsequently, fully interconnected β‐TCP composite ceramic sphere‐based (TCCS) scaffolds were fabricated by sintering the randomly packed β‐TCP/PG composite spheres. The results manifested that at least 20% microcrystalline cellulose (MCC) was required to obtain β‐TCP/PG composite spheres in good spherical shape. The prepared TCCS scaffolds showed hierarchical pore architecture, which consisted of interconnected macropores among the spheres, a hollow core in the sphere, plentiful medium‐sized pores in the sphere shell and micropores among the grains. The pore architecture and mechanical strength of the TCCS scaffolds could be tailored by adjusting the sintering temperature, sphere size, and amounts of PG and MCC in the β‐TCP/PG composite spheres. This work is believed to open up new paths for the design and fabrication of interconnected bioceramic scaffolds for application in bone regeneration.

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