Promoting lumbar spinal fusion by adenovirus-mediated bone morphogenetic protein-4 gene therapy

To determine whether an adenoviral construct containing bone morphogenetic protein-4 (BMP-4) gene can be used for lumbar spinal fusion.Twelve New Zealand white rabbits were randomly divided into two groups, 8 in the experimental group and 4 in the control group. Recombinant, replication-defective type 5 adenovirus with the cytomegalovirus (CMV) promoter and BMP-4 gene (Ad-BMP-4) was used. Another adenovirus constructed with the CMV promoter and beta-galactosidase gene (Ad-beta-gal) was used as control. Using collagen sponge as a carrier, Ad-BMP-4 (2.9 multiply 10(8) pfu/ml ) was directly implanted on the surface of L(5)-L(6) lamina in the experimental group, while Ad-beta-gal was implanted simultaneously in the control group. X-ray was obtained at 3, 6, and 12 weeks postoperatively to observe new bone formation. When new bone formation was identified, CT scans and three-dimensional reconstruction were obtained. After that, the animals were killed and underwent histological inspection.In 12 weeks after operation, new bone formation and fusion were observed on CT scans in the experimental group, without the evidence of ectopic calcification in the canal. Negative results were found in the control group. Histological analysis demonstrated endochondral bone formation at the operative site and fusion at early stage was testified.In vivo gene therapy using Ad-BMP-4 for lumbar posterolateral spinal fusion is practicable and effective.