Characteristics of Newly Formed Bone During Guided Bone Regeneration: Analysis of cbfa-1, Osteocalcin, and VEGF Expression
This study investigated the expression of core-binding factor alpha-1 (cbfa-1), osteocalcin, and vascular endothelial growth factor (VEGF) relative to new bone formation during guided bone regeneration; cbfa-1 is a prerequisite transcription factor for osteoblastic differentiation. Osteocalcin, a bone-specific extracellular matrix protein, is a marker of mature osteoblasts, whereas VEGF, a mitogen for endothelial cells, is a polypeptide thought to stimulate new blood vessel formation. Membranes (expanded polytetrafluoroethylene) were applied to defects created in the left tibiae of rats, while right tibial defects remained uncovered as a control group. Animals were killed 6, 8, or 10 days later. The cbfa-1 was detected by immunohistochemistry, and reverse transcriptase-polymerase chain reaction was used to detect osteocalcin and VEGF. The ratio of cbfa-1 positive cells in experimental bone defects was higher than in the control group. Osteocalcin mRNA expression increased gradually in the control group but significantly in the experimental group over time. The VEGF mRNA expression in the experimental group at 10 days was significantly lower than in the control group. These findings suggested that osteogenic cells differentiated into osteoblasts in the membrane-covered defects and that the bone healing process would be completed at an early stage.Abstract
Pictures of rat tibiae in which a defect was created (a) and covered by expanded polytetrafluoroethylene membrane (b), and the scheme of the defect seen in a cross-section of the tibia (c). CB indicates compact bone; BM, bone marrow
Immunohistochemistry of core-binding factor alpha-1 (cbfa-1) staining. (a) control group at 6 days. (b) Experimental group at 6 days. (c) Control group at 10 days. (d) Experimental group at 10 days. (e) Scheme of the area (□) for pictures of a to d. At 6 days, cbfa-1 positive cells were found at the lower side in control group, but were also observed diffusely in the upper and lower sides in experimental group. At 10 days, cbfa-1 positive cells were observed at both the upper and lower sides in control group, and the number of cbfa-1 positive cells in experimental group was reduced
Contributor Notes
Shiho Tanaka, DDS, PhD, is a postgraduate student in the Department of Clinical Pathophysiology, and Kenichi Matsuzaka, DDS, PhD, is an associate professor, Daisuke Sato, DDS, is a postgraduate student, and Takashi Inoue, DDS, PhD, is a professor, Oral Health Science Center HRC7, Tokyo Dental College, 1-2-2, Masago, Mihama-ku, Chiba, 261-8502 Japan. Address correspondence to Dr Kenichi Matsuzaka (matsuzak@tdc.ac.jp).