Evaluation of Bone Sialoprotein Coating of Three-Dimensional Printed Calcium Phosphate Scaffolds in a Calvarial Defect Model in Mice

The bioactive coating of calcium phosphate cement (CPC) is a promising approach to enhance the bone-healing properties of bone substitutes. The purpose of this study was to evaluate whether coating CPCs with bone sialoprotein (BSP) results in increased bone formation. Forty-five female C57BL/6NRj mice with an average age of six weeks were divided into three groups. Either a BSP-coated or an uncoated three-dimensional plotted scaffold was implanted into a drilled 2.7-mm diameter calvarial defect, or the defect was left empty (control group; no CPC). Histological analyses revealed that BSP-coated scaffolds were better integrated into the local bone stock eight weeks after implantation. Bone volume/total volume (BV /TV) ratios and bone thickness at the bone-implant contact were analyzed via micro computed tomography (mu CT) after eight weeks. BSP-coated scaffolds and uncoated CPC scaffolds increased bone thickness in comparison to the control (CPC + BSP: 691.1 +/- 253.5 mu m, CPC: 603.1 +/- 164.4 mu m, no CPC: 261.7 +/- 37.8 mu m, p < 0.01). Accordingly, BV/TV was enhanced in both scaffold groups (CPC + BSP: 1.3 +/- 0.5%, CPC: 0.9 +/- 0.5%, no CPC: 0.2 +/- 0.3%, p < 0.01). The BSP coating showed a tendency towards an increased bone thickness (p = 0.18) and BV/TV (p = 0.18) in comparison to uncoated CPC scaffolds. However, a significant increase in bone formation through BSP coating was not found.