Combination of beta-TCP and BMP-2 gene-modified bMSCs to heal critical size mandibular defects in rats

Objective: To investigate the effects of mandibular defects repaired by a tissue engineered bone complex with beta-tricalcium phosphate (beta-TCP) and bone morphogenic protein-2 (BMP-2) gene-modified bone marrow stromal cells (bMSCs). Materials and methods: bMSCs derived from Fisher 344 rats were cultured and transduced with adenovirus AdBMP-2, AdEGFP gene in vitro. Osteogenic differentiation of bMSCs was determined by alkaline phosphatase staining, von Kossa assay and reverse transcription-polymerase chain reaction. Gene transduced or untransduced bMSCs were seeded on beta-TCP scaffolds to repair mandibular full thickness defects with a diameter of 5 mm. Eight weeks post-operation, X-ray examination, micro-computerized tomography and histological and histomorphological analysis were used to evaluate the bone healing effects. Results: Alkaline phosphatase staining and mineralized nodules formation were more pronounced in AdBMP-2 group 14 days after gene transduction when compared with that of AdEGFP or untransduced group. The mRNA expression of osteopontin and osteocalcin also significantly increased 9 days after AdBMP-2 gene transduction. Mandibular defects were successfully repaired with AdBMP-2-transduced bMSCs/beta-TCP constructs. The percentage of new bone formation in AdBMP-2 group was significantly higher than that of other control groups. Conclusions: Bone morphogenic protein-2 regional gene therapy together with beta-TCP scaffold could be used to promote mandibular repairing and bone regeneration.