Porcine bone incorporated with 4-hexylresorcinol increases new bone formation by suppression of the nuclear factor kappa B signaling pathway

Objective: The objectives of this study were to evaluate the suppression of the nuclear factor kappa B (NF-kB) pathway by 4-hexylresorcinol (4HR), which was activated by tumor necrosis factor-a (TNF-a) in osteoblasts, and new bone formation by 4HR-incorporated porcine bone in an animal model. Study Design: For the confirmation of successful incorporation of 4HR into porcine bone, scanning electron microscopy (SEM) and Fourier transform-infrared (FT-IR) analysis were performed. High performance liquid chromatography was performed for the analysis of the 4HR release profile from porcine bone. MC 3T3-E1 cells were used for the analysis of the NF-kB signaling pathway activation by western blotting and real-time reverse transcriptase polymerase chain reaction. New bone formation and the analysis of marker protein expression were studied in a rat calvarial critical-sized defect model. Results: Both SEM and FT-IR analysis demonstrated successful incorporation of 4HR into porcine bone. Approximately 30% of 4HR was steadily released from porcine bone for 18 days. 4HR suppressed the NF-kB signaling pathway, which was activated by TNF-a application in MC 3T3-E1 cells. Histological analysis revealed that porcine bone particles with incorporated 4HR showed significantly greater new bone formation than those without 4HR at 4 and 8 weeks after operation (P < 0.05). The expression intensities of alkaline phosphatase, osteoprotegerin, and osteocalcin were also higher in the 4HR-incorporated group. Conclusion: The application of 4HR suppressed the NF-kB signaling pathway in osteoblasts and 4HR-containing porcine bone particles promoted new bone formation in a rat calvarial defect model.