HA/PEEK Scaffolds with Modified Crystallinity via 3D-bioprinting for Multiple Applications in Hard Tissue Engineering

Abstract Background Hard tissues, especially teeth and bones, are highly mineralized and the large-scale defect or total loss of them is irreversible. Scaffolds fabricated with polyether ether ketone (PEEK) and hydroxyapatite (HA) were considered as substitute materials with osteogenic properties but poor mechanical properties. There is a lack of a construction strategy of HA/PEEK scaffolds that can balance mechanical and biological properties and the in vitro and in vivo evaluation of them. Methods Based on fused deposition melting (FDM), we regulated the crystallinity and mixing ratio of HA of HA/PEEK scaffolds, and explored the material characterization including crystallinity, element content and mechanical properties and biological properties including cell proliferation, migration, osteogenic differentiation of different scaffolds. And we further mimicked the clinical application on the Beagles by implanting the scaffolds to reconstruct the defect of teeth, mandibles and ribs. Results We found that the 3D-20%HA/PEEK scaffolds with low crystallinity achieved the required strength and elasticity, and exhibited the characteristics of promoting the proliferation, migration and osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs). The results of the implantation of Beagles’ teeth, mandible and rib showed that the 3D-20%HA/PEEK scaffold with low crystallinity could well withstand the local complex force in the defect area and combine well with natural bone tissue. Conclusion The HA/PEEK scaffolds constructed with this strategy had appropriate mechanical properties to withstand complex forces, and good bone regeneration effect, which made them practical and versatile on hard tissue engineering.