STUDY DESIGN: An in-vivo experiment. OBJECTIVES: To evaluate the feasibility of achieving bone formation by percutaneous gene delivery, with plasmid DNA encoding BMP-7(OP-1). SUMMARY OF LITERATURE REVIEW: Currently, the preferred method for posterolateral spinal fusion involves decortication of the transverse process, followed by a graft of autogenous bone harvested from the iliac crest. Unfortunately, this procedure suffers from significant morbidity, including blood loss, infection and persistent pain at the harvest site. MATERIAL AND METHODS: 24 Sprague-Dawley rats, weighing approximately 250~300 g, were used. The percutaneous injection was attempted above both the L5 transverse processes. The animals were divided into three groups, according to the injection materials: 1) OP-1 gene/collagen, 2) recombinant OP-1 protein/collagen and 3) control of PBS/collagen. At 2 and 4 weeks post-injection, the animals were sacrificed. The gross, radiological and histological findings were analyzed. RESULTS: No bone was detected grossly by manual palpation or radiography in the groups receiving OP-1 gene/collagen at either time point. The histological findings revealed the initiation of endochondral bone formation within the paraspinal muscle, directly above the L5 transverse process. In the rhOP-1 protein/collagen groups, the gross, radiological and histological findings revealed extensive cartilage and bone formation at both 2 and 4 weeks. CONCLUSION: In conclusion, the authors confirmed the feasibility of achieving bone formation by percutaneous gene delivery, with plasmid DNA encoding BMP-7(OP-1).
Animals ; Cartilage ; DNA ; Osteogenesis ; Palpation ; Paraspinal Muscles ; Plasmids ; Radiography ; Rats, Sprague-Dawley ; Spinal Fusion* ; Transplants