Comparison of gene expression of tissue inhibitor of matrix metalloproteinase-1 between continuous and intermittent distraction osteogenesis: a quantitative study on rabbits

Abstract

BACKGROUND: Distraction osteogenesis is a controlled surgical procedure that initiates a regenerative process and uses mechanical strain to enhance the biological responses of the injured tissues to create new bone. To explore the effect of high-frequency mechanical traction on the expression of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), we compared the gene expression of TIMP-1 between continuous and intermittent distraction osteogenesis using a rabbit model of mandibular lengthening. MATERIALS AND METHODS: Forty adult New Zealand white rabbits were randomly assigned to the intermittent and continuous distraction groups. A unilateral mandibular osteotomy was performed and a custom-designed manual-driven or auto-driven distractor was bridged over the osteotomy segments. Animals were sacrificed at day-6, day-10, day-14 and day-21 after osteotomy. Samples were examined with real-time polymerase chain reaction (PCR). RESULTS: Real-time PCR examination showed significantly higher mRNA levels of TIMP-1 under continuous distraction than that under intermittent distraction at day-6 and day-10. No significant differences were found at day-14 and day-21. CONCLUSION: High-frequency traction provides a good mechanical environment for accelerating bone formation by up-regulating TIMP-1.