Abstract:

BACKGROUND: The previous studies have shown that electroporation-mediated recombinant plasmid pIRES-hBMP2-hVEGF165 can promote the early angiogenesis and new bone formation in the traction zone.
OBJECTIVE: To investigate the effect of gene transfection at different time on the new bone formation in the traction zone during mandibular distraction in rabbits, so as to explore the optimal time for gene therapy and obtain a better treatment effect.
METHODS: Forty-eight New-Zealand rabbits were employed. After accomplished the bilateral mandibular osteotomy and distractor implantation under general anaesthesia, the rabbits were randomly divided into four groups. The bilateral traction zones were transfected with the 2 μg (0.1g/L) recombinant plasmids pIRES-hBMP2-hVEGF165 at latency period, traction period and consolidation period, respectively, and the rabbits in these three groups received electroporation stimulation. The simple traction group only received traction without gene transfection. The rabbits in each group received traction at 3 days after modeling with the rate of 0.8 mm/d and once per day, and continuous traction for 10 days; three rabbits were sacrificed in each group at 1, 2, 4 and 8 week. The new tissues in the mandibular traction zone were cut for histological observation and histomorphometry analysis.
RESULTS AND CONCLUSION: Histological examination and histomorphometry analysis showed that amounts of newly formed vessels, osteoblasts and mesenchymal cells of distraction period transfection group were greater than those of the latency period transfection group, consolidation period transfection group and simple traction group, and the new bone volume and the width of bone trabecula in the distraction period transfection group were higher than those in the other three groups (P < 0.05). It is better to transfect gene at the beginning of traction (distraction period) than at other stages of traction; in this way, we can obtain more remarkable effects on new bone formation. It suggests that the distraction stage is the optimal time for gene therapy.

Key words: electroporation, gene therapy, traction, transfection