Bone healing with oxytocin‐loaded microporous β‐TCP bone substitute in ectopic bone formation model and critical‐sized osseous defect of rat

Abstract

This study investigated the efficacy of the hypothalamic nonapeptide oxytocin (OT) by direct delivery to local defects using a microporous β-tricalcium phosphate (TCP) as the carrier for the future applications as a method to achieve predictable bone regeneration of large osseous defects requiring sinus bone graft and guided bone regeneration procedures for implant placement. Both the ectopic and new bone formation induced by the OT-loaded microporous β-TCP powder was histomorphometrically compared with unloaded β-TCP in a subcutaneous ectopic bone formation model and calvarial critical-sized defects (CSDs) in 45 rats. The OT-loaded β-TCP clearly enhanced ectopic bone formation compared with the unloaded control group. A High initial OT dose (250μg) significantly increased ectopic bone formation at an early healing time-point compared with a lower OT dose (50μg). The OT-loaded samples displayed greater new bone formation in the rat calvarial CSDs. Extensive new bone formation was achieved in the calvarial CSDs with the higher OT dose. These results suggest that local OT delivery to bone substitute promotes new bone formation via an osteoinductive mode of action.