Hydroxyapatite Whisker-reinforced Composite Scaffolds Through 3D Printing for Bone Repair

Development of bioactive scaffolds with controllable architecture and high osteogenic capability is essential for bone tissue engineering. In this study, hydroxyapatite whiskers (HAPw) were added into polycaprolactone (PCL) matrix materials to fabricate scaffolds through 3D printing technique. The HAPw could distribute homogeneously in PCL and in alignment with 3D printing directions by adjusting squeeze parameters. The mechanical strength of PCL-HAPw composite scaffolds increased along with the increase of HAPw content. Adding 33wt% of HAPw remarkably enhanced the compressive strength of PCL scaffolds to 3 times, which can also lower the surface contact angles from 100 of PCL to 50 and thus enhance the surface hydrophilicity. In vitro culturing experiments of human bone marrow mesenchymal cells (hBMSCs) demonstrated that the incorporation of HAPw promoted their bioactive and osteogenic properties, including better cytocompatibility, cell adhesion, proliferation, alkaline phosphatase (ALP) activity, and bone-related gene expressions (OCN, RUNX2). Therefore, 3D-printed HAPw-PCL composite scaffolds showed improved mechanical strength and osteogenesis properties compared to pure PCL scaffolds, and suggest promising applications in bone regeneration.