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.