O-phospho-L-serine modified calcium phosphate cements – material properties,in vitro andin vivo investigations

One of the most important requirements for calcium phosphate bone cements (CPBC) is remodelling in vivo. Degradation of the artificial material and the formation of native new bone matrix have to interdigitate to avoid instability. The remodelling process should not last longer than one year. In this study a CPBC was modified with O-phospho-L-serine (phosphoserine) to improve the material properties in order to speed up remodelling in vivo. The results showed that the modified cements exhibit a nano-crystalline microstructure with a high specific surface area and increased compressive strength (about 50%). Metabolic activity of osteoblasts was improved on the modified material. Monocytes were found to be highly activated on the cements containing phosphoserine. In addition the formation of multinucleated giant cells (osteoclast-like cells) was not impaired on phosphoserine modified cement composites. In vivo experiments in Wistar rats and mini pigs clearly revealed that phosphoserine modified cements showed a higher capability of remodelling compared to the cements without phosphoserine.