Novel Alveolar Bone Regeneration Therapy via Bone Morphogenetic Protein-2/7 Double Gene Transfer

Objectives: Alveolar bone defects are generally reconstructed using bone grafts or artificial bone grafts. We aim to develop non-surgical methods for alveolar bone regeneration therapy. We previously successfully constructed a gene transfer system using a combination of a non-viral bone morphogenetic protein (BMP)-2/7 double gene expression vector and in vivo electroporation. In the present study, we applied our gene transfer system to periodontal tissue to achieve alveolar bone regeneration.
Methods: We injected green fluorescent protein, lacZ, and the BMP-2 or BMP-2/7 gene expression vector into the palatal periodontal tissue of 9-week-old male Wistar rats, before immediately performing electroporation. In the histological analyses, we obtained time course samples and conducted hematoxylin-eosin staining and immunohistochemical staining. To investigate how gene transfer to periodontal tissue affects bone remodeling, we performed double bone staining using calcein and tetracycline.
Results: One day after the gene transfer procedure, abundant inflammatory cells appeared. However, at 7 days after the gene transfer procedure there were no differences in the number of such cells compared with the control side. On the other hand, at 7 days after the BMP-2/7 gene transfer new bone-like tissue had formed on the alveolar bone. Double bone staining did not show any differences between the tissue subjected to gene transfer and the control side for 7 days. In the double bone staining, the lines of calcein and tetracycline were labeled in the alveolar bone. The labeled line on the side of the BMP-2/7 gene transfer was wider than that on the control side.
Conclusions: We safely and efficiently transferred genes to the periodontal tissue of rats. We only detected new bone-like tissue in the periodontal tissue subjected to BMP-2/7 gene transfer. Therefore, our results might aid the development of a new non-surgical therapy for alveolar bone regeneration.