Repair of canine mandibular bone defects with bone marrow stromal cells and porous β-tricalcium phosphate

Tissue engineering has become a new approach for repairing bone defects. Previous studies have been limited to the use of slow-degradable scaffolds with bone marrow stromal cells (BMSCs) in mandibular reconstruction. In this study, a 30 mm long mandibular segmental defect was repaired by engineered bone graft using osteogenically induced autologouse BMSCs seeded on porous β-tricalcium phosphate (β-TCP, n=5). The repair of defects was compared with those treated with β-TCP alone (n=6) or with autologous mandibular segment (n=4). In the BMSCs/β-TCP group, new bone formation was observed from 4 weeks post-operation, and bony-union was achieved after 32 weeks, which was detected by radiographic and histological examination. In contrast, minimal bone formation with almost fibrous connection was observed in the group treated with β-TCP alone. More importantly, the engineered bone with BMSCs/β-TCP achieved a satisfactory biomechanical property in terms of bending load strength, bending displacement, bending stress and Young's modulus at 32 weeks post-operation, which was very close to those of contralateral edentulous mandible and autograft bone (p>0.05). Based on these results, we conclude that engineered bone from osteogenically induced BMSCs and biodegradable β-TCP can well repair the critical-sized segmental mandibular defects in canines.