Enhanced Repairing of Critical-Sized Calvarial Bone Defects by Mussel-Inspired Calcium Phosphate Cement

The goal of this study is to investigate the biological response of mussel-inspired calcium phosphate cement (CPC) in vivo. Polydopamine (PDA), which is analogous to that of mussel adhesive proteins, was added in CPC. PDA-CPC was implanted into the femur, muscle, and critical-sized calvarial bone defects of rabbits. Histomorphometry of the sequential fluorescence sections showed that PDA-CPC was capable of forming more newborn bone than the control-CPC. More new bone, bone marrow cavity, and blood vessel were observed in PDA-CPC than in the control-CPC in decalcified and undecalcified histological sections. Necrosis bone was not observed in PDA-CPC, whereas it appeared in the control-CPC after 2 weeks. The histological sections in muscle witnessed that there was more ingrowth of collagen in PDA-CPC than that in the control-CPC. There were no significantly difference in the number of leukocyte between PDA-CPC and the control-CPC in blood. It was confirmed that the addition of PDA enhanced the bone repairing ability and biocompatibility of PDA-CPC. Push-out testing indicated that PDA increased the bonding strength between PDA-CPC and host bone in the early stage. These present results indicated that PDA-CPC might be one potential bone graft with gratifying biocompatibility and enhanced bone repairing.