Effect of Adeno-Associated Virus-Transfected Mesenchymal Stem Cells Containing Agents on Bone Formation in Extended Inter-Premaxillary Suture in Rats

The aim of this study was to investigate the histomorphometric effects of bone marrow-derived mesenchymal stem cells (MSCs) transfected with Adeno Associated Virus (AAV) and containing bone morphogenic protein 7 (Bmp7) or osteoprotegerin (OPG) on bone formation after injection into inter-premaxillary suture in rats with Bmp7 or OPG alone.

In 4 groups (each group n:9), different chemical solutions, namely AAV-Bmp7, AAV-OPG and AAV-Bmp7-OPG and AAV-EGF (control group) were injected into the interpremaxillary suture of rats. Bone volumes (BV), soft tissue volume (STV) and total bone volumes (TBV) of 10μm serial selection with hemotoxylin and eosin staining were calculated according to the Cavalieri principle. Each point in the region of interest was 1000μm3.

The BV for AAV-Bmp7, AAV-OPG, AAV-Bmp7-OPG and AAV-EGF were 46.98±1.50 mm3, 49.40±4.72mm3, 42.58±2.89mm3 and 38.82±0.76mm3, respectively. The STV was 11.53±0.99, 13.31±1.88, 8.00±4.43 and 9.57±1.90mm3 for Bmp7, OPG, AAV-Bmp7-OPG and AAV-EGF, respectively. TBV was 58.34±2.28mm3, 63.83±5.17mm3, 53.74±3.34mm3 and 48.13±1.54mm3 for AAV-Bmp7, AAV-OPG, AAV-Bmp7-OPG and AAV-EGF, respectively. The comparison between BV, STV, TBV for AAV-OPG showed a statistically significant difference (p=0.001) compared to AAV-Bmp7 or AAV-Bmp7-OPG and AAV-EGF.

During tooth movement and bone remodeling, the ratio of soft and bone tissues is maintained by OPG. Although Bmp7 is not as effective as OPG in bone remodeling, both can reduce the retention time and the risk of recurrence.