ABSTRACT
STUDY DESIGN: An in-vitro experiment using human ligamentum flavum (LF) and the adnovirus-BMP-2 construct, Ad/BMP-2. OBJECTIVES: To determine the dual roles of LF as an osteoinductive agent and carrier for ex-vivo gene transfer. SUMMARY OF LITERATURE REVIEW: LF is known to have osteogenic potential. Pathologically, ossified LF may cause myelopathy and radiculopathy. BMP-2 is known as an important factor in the differentiation, and maintenance, of osteoblast phenotypes. Ex-vivo gene transfer, using human LF for spinal fusion, has never been attempted before. MATERIALS AND METHODS: The LF cells were cultured from the degenerated LF of spinal stenosis patients. An adenovirus construct, containing BMP-2 cDNA (Ad/BMP-2), was also produced. The LF cell cultures were exposed to the adenoviral construct. The Osteocalcin expression was analysed by Western blot analysis. The osteocalcin and BMP-2 mRNA expressions were analysed by RT-PCR. Bone formation was assessed by alkaline phosphatase and Von Kossa stains. RESULTS: The LF cell cultures, with Ad/BMP-2, showed transgene expression in the Western blot analysis. Also, the cultures exhibited the mRNA expressions of both osteocalcin and BMP-2, in a dose-dependent manner. The LF cultures, with Ad/BMP-2, demonstrated alkaline phosphatase expression and bone nodule formations from the Von Kossa staining. CONCLUSION: The genetically modified LF strongly induced osteogenesis, which can be used during a spinal fusion, as an osteoinductive agent and carrier, for ex-vivo gene transfer.
