Natural calcium phosphate cements (CPCs) derived from sintered animal bone have been investigated to treat bone defects, but their low mechanical strength remains a critical limitation. Graphene improves the mechanical properties of scaffolds and promotes higher osteoinduction. To this end, reduced graphene oxide-incorporated natural calcium phosphate cements (RGO-CPCs) are fabricated for reinforcement of CPCs' characteristics. Pulsed electromagnetic fields (PEMFs) were additionally applied to RGO-CPCs to promote osteogenic differentiation ability. The fabricated RGO-CPCs show distinct surface properties and chemical properties according to the RGO concentration. The RGO-CPCs' mechanical properties are significantly increased compared to CPCs owing to chemical bonding between RGO and CPCs. In in vitro studies using a mouse osteoblast cell line and rat-derived adipose stem cells, RGO-CPCs are not severely toxic to either cell type. Cell migration study, western blotting, immunocytochemistry, and alizarin red staining assay reveal that osteoinductivity as well as osteoconductivity of RGO-CPCs was highly increased. In in vivo study, RGO-CPCs not only promoted bone ingrowth but also enhanced osteogenic differentiation of stem cells. Application of PEMFs enhanced the osteogenic differentiation of stem cells. RGO-CPCs with PEMFs can overcome the flaws of previously developed natural CPCs and are anticipated to open the gate to clinical application for bone repair and regeneration.
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