[The effect of bone morphogenetic protein-2 and osteoprotegerin in trans-sutural distraction osteogenesis]

To determine if locally administered bone morphogenetic protein-2 (BMP-2) and osteoprotegerin (OPG) improved osteogenesis and new bone formation by trans-sutural distraction osteogenesis.

Twenty four dogs were divided into three groups randomly and received new internal trans-sutural distraction osteogenesis treatment. Five days after operation, infusion apparatus with double-tube was inserted to submucosa near the distracted zone to deliver controlled release agent of recombinant human bone morphogenetic protein-2/poly (lactic-co-glycolic acid)/fibrin sealant (rhBMP-2/PLGA/FS) in group A and group C. Recombinant human osteoprotegerin/fibrin sealant (rhOPG/ FS) was injected three weeks later in group B and group C. Histology staining and bone histomorphometry were used to measure the changes of maxillary bone sutura after distraction for 1, 2, 4 and 6 weeks.

New bone formation observed in distracted zone showed a significant increase in group A and C. Transmission electron microscope showed the osteoblast and osteocyte were active with dilated rough endoplasmic reticulum and a large number of chondriosomes and Golgi complex. After distraction for 6 weeks, indexes of osteoblast of group A, B, and C were 38.5 +/- 7.7, 35.7 +/- 6.5, and 41.7 +/- 11.0, indexes of osteoclast (Ioc) were 5.9 +/- 1.0, 1.2 +/- 0.3, and 2.8 +/- 0.4, bone trabecula thicknesses were (38.36 +/- 13.28), (66.20 +/- 9.16), and (51.85 +/- 9.92) microm respectively. Increased bone density and decreased Ioc were found in group B and C.

The new elastic distractor is effective in inducing new bone formation. BMP-2 and OPG combination acts synergistically, and leads to significant enhancement of bone formation and remodeling.