Effect of silicon or cerium doping on the anti-inflammatory activity of biphasic calcium phosphate scaffolds for bone regeneration

Biphasic calcium phosphate (BCP) bioceramics composed of hydroxyapatite and β-tricalcium phosphate have attracted considerable attention as ideal bone substitutes for reconstructive surgery, orthopedics, and dentistry, owing to their similar chemical composition to bone mineral and biocompatibility. The addition of trace elements to BCP bioceramics, such as magnesium (Mg), cerium (Ce), and silicon (Si), can alter the physicochemical and biological properties of the resulting materials. To improve the anti-inflammatory activity of a pure BCP scaffold, this study developed a simple wet chemical precipitation and gel-casting method to fabricate microporous BCP scaffolds containing Si or Ce. The BCP scaffolds exhibited interconnected microporous structures with uniform micropores and unequiaxed grains. No changes in the phase composition and microstructure of the scaffolds with the Si or Ce doping were observed. Conversely, Si or Ce doping into the BCP crystal lattice influenced the in vitro biological activity of the scaffolds and the bone-forming ability of the cells cultured on the BCP scaffolds. The results of biological activity assays demonstrated that Ce-BCP promoted cell proliferation and osteogenic differentiation more effectively than the other scaffolds. In particular, Ce-BCP significantly suppressed the expression of bone-active cytokines via the anti-inflammatory and anti-oxidative effects. Therefore, Si- or Ce-doped BCP scaffolds can contribute to providing a new generation of bone graft substitutes.