Gene Therapy using Non-viral Gene Expression Vector and in vivo Electroporation for Bone Regeneration: Challenge to Gene Transfer into the Periodontal Tissues

- It is well known that bone morphogenetic protein (BMP) induces ectopic bone formation when the recombinant protein or BMP gene is transferred into the skeletal muscle. In our previous studies, we developed a novel method for BMP gene transfer, which is combination with non-viral gene expression vector and in vivo electroporation. On the other hand, in the BMP family, BMP-2/4 or BMP-2/7 heterodimer has stronger potential for bone induction compared with BMP-2, BMP-4 or BMP-7 homodimer. Then, we constructed BMP-2/7 heterodimer produced vector: pCAGGS-BMP-2/7. When we injected pCAGGS-BMP-2/7 plasmid vector into the skeletal muscles and immediately performed in vivo electroporation, the ectopic bone formation was induced quickly on 10 days after gene transfer. For clinical application, we need more safe procedure on in vivo electroporation under the condition of lower voltage than 100 voltage. If we set the condition: 50 voltage and 8 pulses, the efficiency of gene transfer was also reduced by 50%. But, when we induced pulse number, it recovered. We evaluated proper voltage and pulse number as the same gene transfer efficiency of 100 voltage. We often use bone prosthetic material and autogenous bone graft for alveolar bone defect caused by periodontal disease or trauma. But, these therapies sometimes have some risk for patients such as infection or fractures. In this study, we tried to apply this gene transfer system for alveolar bone regeneration of rats under the condition less 50 voltage. Our developed gene therapy system for alveolar bone regeneration will be with more safety and with fewer burdens on the patient in the future.