3D-printed Bilayer Cortico-cancellous Calcium Phosphate Cement-based Bone Scaffold

Objectives: Traditional fabrication methods of porous bone scaffolds are unable to accurately reproduce the desirable cortico-cancellous morphology and structure of the bone. The aim of this study was to exploit the advantage of 3D-printing to fabricate β-Tricalcium phosphate (TCP)-based scaffold that replicates the cortico-cancellous bilayer bone architecture.
Methods: An injectable TCP paste containing Sodium Tripolyphospahte (TPP), Carboxymethylcellulose Sodium (CMC), and β-TCP was formulated. Bilayer scaffolds with distinct compact and porous layers were printed using a 3D bio-plotting system. The scaffolds were then air dried overnight and sintered. The scaffolds were characterized using laser microscopy, micro CT scanning, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The young’s modulus and ultimate compressive strength of the scaffolds were measured using a mechanical testing machine and the cell viability of normal human osteoblasts cultured on the scaffolds was assessed using Presoblue (PB) assay.
Results: Laser microscope imaging showed that pore sizes were 242.2± 24.3 µm and 410.5± 27.9 µm for the cortical and cancellous layers, respectively. Micro CT revealed overall porosity and interconnectivity of 61.8±1.4% and 208707.5±52405, respectively. Mechanical properties were within the range of human cancellous bone with 10.0 ± 2.4 MPa strength and 55.5 ± 5.7 MPa young’s modulus. The XRD analysis showed that the phase composition of the printed scaffolds was almost identical to pure TCP. The SEM and cell vitality assessment indicated significant osteoblastic proliferation on the surface of the scaffolds.
Conclusions: The 3D-printed bilayer bone scaffold developed in this study has the potential to be optimized and used as a suitable scaffold for bone tissue engineering and regeneration.