Calcium phosphate biomaterials have been widely used as bone substitute materials in clinical applications due to their good biocompatibility and osteoconduction. However, they are usually plagued by low inherent mechanical properties. During this study we synthesised and analysed nanostructured calcium phosphate bone cements based on α-tricalcium phosphate (α-TCP) reinforced with nanoneedles of hydroxyapatite (HAP) (1, 3, 5, 10 and 20%) with strictly controlled porosity so as to optimise both mechanical properties and osteoblast nesting. Scanning electron microscope (SEM) images showed that the surface microstructure of the cements after hardening was composed of plate-like crystals. The compressive strength of pure cements was at 34.3±1.7 MPa while in the case of composite cements is strongly depended upon the HAP content. By increasing the HAP content until 20% the compressive strength drastically deceased until 4.9±0.2 MPa which was within the cancellous bone ranges between 1.5 and 45 MPa. We further analyzed the ability of the new biocements to induce the proliferation and survival of the pre-osteoblast cell line MC3T3E1 through DNA and protein quantification. In addition, cell morphology was observed with SEM after 1 and 7 days of culture. Moreover, the osteoblastic induction was quantified by alkaline phosphatase (ALP) activity measurements and the morphology of the cells with SEM after 14 days of culture in the presence of the osteogenic factors ascorbic acid and β-glycerophosphate. Our results indicate that biocements with certain ratio of α-TCP-HAP composite are tolerated as well as pure α-TCP with regard to their osteoinductive and osteogenic properties. In conclusion, pure or HAP loaded calcium phosphate bone cements are suitable for low stress loading locations and display similar biocompatibility.
Disclosure: The authors declared no competing interests. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program Education and Lifelong Learning of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALES (grant MIS 379380). Investing in knowledge society through the European Social Fund.