Bone morphogenetic protein-2 for bone regeneration – Dose reduction through graphene oxide-based delivery

High doses of bone morphogenetic protein-2 (BMP-2) are required for effective bone regeneration. However, these high doses often cause undesirable adverse effects, including bone overgrowth, osteolysis, and activation of the immune response, and raise treatment costs. In an effort to reduce the BMP-2 dose to avoid or diminish side effects, we investigated whether delivery of BMP-2 using graphene oxide (GO) can reduce the BMP-2 dose for bone regeneration. Delivery of BMP-2 using GO flakes suspended in fibrin gels (GO/F) resulted in significantly greater osteogenic differentiation of human bone marrow-derived mesenchymal stem cells in vitro, and at various doses of BMP-2, significantly greater amounts of bone regeneration in mouse calvarial defects occurred than when fibrin gel (F) alone was used. A half-dose of BMP-2 delivered by GO/F resulted in bone regeneration similar to that resulting from a full dose of BMP-2 delivered by F. The enhanced bone regeneration efficacy was likely due, at least in part, to the sustained release, higher structural stability, and higher bioactivity of BMP-2 delivered by GO/F compared to BMP-2 delivered by F. Therefore, GO may be an effective carrier for BMP-2 to reduce the BMP-2 dose and avoid adverse effects.