Impacts of channel direction on bone tissue engineering in 3D-printed carbonate apatite scaffolds

• Published in: Materials & design 2021-06, Vol.204, p.109686, Article 109686
• Main Authors: Hayashi, Koichiro, Kato, Nao, Kato, Masaki, Ishikawa, Kunio
• Format: Article
• Language: English
• Subjects: 3D printer; Bone regeneration; Carbonate apatite; Regenerative medicine; Tissue engineering; Tissue scaffold
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2021.109686

[Display omitted] •Scaffolds with channels directed differently are fabricated by 3D printing.•Channel direction is a critical parameter for bone regeneration.•Channel connection to the periosteum is important for a smooth replacement by bone.•Biaxial channels result in too rapid scaffold resorption and bone disappearance.•Micro/nanopores are insufficient, and channels are necessary for bone regeneration. Although the channel architecture of a scaffold is critical for bone regeneration, little is known for the channel direction. In this study, four types of carbonate apatite cylindrical scaffolds; scaffolds with biaxial channels (VH-scaffold), with uniaxial vertical channels (V-scaffold), with uniaxial horizontal channels (H-scaffold), and without channels (N-scaffold), were implanted in a rabbit femur defect for 4 and 12 weeks. Although the largest bone was formed 4 weeks post-implantation in the VH-scaffold, newly formed bone disappeared with the scaffold after 12 weeks. Thus, biaxial channels resulted in the rapid dissolution of the scaffold and were counterproductive in long-term bone regeneration. The V-scaffold that had channels connected to the periosteum was gradually resorbed throughout 12 weeks post-implantation. The percentage of mineralized bone in the V-scaffolds was equal to that in the natural bone. The resorption and bone percentage of H-scaffolds that had no channels connected to the periosteum were slower and lower, respectively, than those of V-scaffolds. Thus, channels should be connected to the periosteum to achieve smooth replacement by the new bone. In the N-scaffold, much less bone was formed inside the scaffold. This study contributes to providing a design guide for scaffold development in bone engineering.