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

Abstract

This study proposes a novel approach, termed extrusion-microdrilling, to fabricate 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, and 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, and 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 EM-TCP group was comparable with that of EM-TCP/SrPG group. At 12 weeks post-implantation, the bone formation percentage of EM-TCP was slightly reduced, while that of EM-TCP/SrPG with 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.