Preparation of macroporous calcium phosphate cement tissue engineering scaffold

Unlike sintered hydroxyapatite there is evidence to suggest that calcium phosphate cement (CPC) is actively remodelled in vivo and because CPC is formed by a low-temperature process, thermally unstable compounds such as proteins may be incorporated into the matrix of the cement which can then be released after implantation. The efficacy of a macroporous CPC as a bone tissue engineering scaffold has been reported; however, there have been few previous studies on the effect of macroporosity on the mechanical properties of the CPC. This study reports a novel method for the formation of macroporous CPC scaffolds, which has two main advantages over the previously reported manufacturing route: the cement matrix is considerably denser than CPC formed from slurry systems and the scaffold is formed at temperatures below room temperature. A mixture of frozen sodium phosphate solution particles and CPC powder were compacted at 106 MPa and the sodium phosphate was allowed to melt and simultaneously set the cement. The effect of the amount of porogen used during processing on the porosity, pore size distribution and compressive strength of the scaffold was investigated. It was found that macroporous CPC could reliably be fabricated using cement:ice ratios as low as 5:2.