Sclerostin Antibody-Loaded Dense Collagen Hydrogels Promote Critical-Size Bone Defect Repair

The management of extensive bone loss remains a clinical challenge. Numerous studies are underway to develop a combination of biomaterials, biomolecules, and stem cells to address this challenge. In particular, the systemic administration of antibodies against sclerostin, a regulator of bone formation, was recently shown to enhance the bone repair efficiency of dense collagen hydrogels (DCHs) hosting murine dental pulp stem cells (mDPSCs). The aim of the present study was to assess whether these antibodies, encapsulated and released from DCHs, could promote craniofacial bone repair by the local inhibition of sclerostin. In vitro studies showed that antibody loading modified neither the hydrogel structure nor the viability of seeded mDPSCs. When implanted in a mouse calvaria critical-size bone defect, antibody-loaded DCHs showed repair capabilities similar to those of acellular unloaded DCHs combined with antibody injections. Importantly, the addition of mDPSCs provided no further benefit. Altogether, the local delivery of antisclerostin antibodies from acellular dense collagen scaffolds is highly effective for bone repair. The drastic reduction in the required amount of antibody compared to systemic injection should reduce the cost of the procedure, making the strategy proposed here a promising therapeutic approach for large bone defect repair.