No abstract

Mechanical force induces an efflux of ATP that regulates osteoblast differentiation. However, the effect of mechanical force-induced ATP efflux on WNT/β-catenin signaling remains unclarified. The aim of this study was to investigate the effect of intermittent compressive force (ICF) and ICF-induced extracellular ATP on osteoblast differentiation via WNT/β-catenin signaling in human mandibular-derived osteoblast precursors (hMOBPs). The hMOBPs were subjected to ICF (1.5 g/cm , 0.3 Hz) for 20 h. To investigate the role of ATP, Apyrase (0.5 units/mL), an enzyme that hydrolyzes ATP, was added 30 min before ICF was applied. The extracellular ATP levels were measured immediately after ICF was removed. The mRNA expression of osteogenic related genes, including WNT was evaluated via quantitative real time polymerase chain reaction. In vitro mineralization was determined by Alizarin Red S staining. The localization of β-catenin was detected using immunofluorescence staining and lentiviral-TOP-dGFP reporter assay. The results demonstrated that ICF increased ATP efflux and in vitro mineralization by hMOBPs. In addition, OSX, ALP, and WNT3A mRNA expression and β-catenin nuclear translocation increased when ICF was applied. The upregulation of these genes was reduced by Apyrase, suggesting the role of ICF-induced ATP on osteoblast differentiation. Notably, ICF altered the mRNA expression of purinergic 2X receptors (P2XRs). A P2X1R antagonist (NF449) downregulated ICF-induced WNT3A, OSX, and ALP mRNA expression. Moreover, when 25 μM α, β-meATP, a P2X1R agonist, was added, WNT3A, and OSX expression increased. In conclusion, our results demonstrate that ICF-induced ATP enhanced hMOBP differentiation. This enhancement was associated with WNT/β-catenin signaling and P2X1R activation.

Purpose: The aim of this study was to investigate the effects of deproteinized bovine bone (DBB, Bio-Oss ® ) and freeze-dried bone allograft (FDBA, SureOss ® ) on bone healing during maxillary sinus floor augmentation (MSFA) using histology, immunohistochemistry, and gene expressions of the marker genes including Runx2, Opn, Ocn, Col1a1, Rankl, and Tnf-α.Materials and Methods: Fourteen participants who required two-stage maxillary sinus augmentation were randomly assigned to DBB and FDBA bone grafting groups.Six months after the sinus augmentation procedure, bone samples were collected before implant placement with a trephine bur. Gene expression of Runx2, Opn, Ocn, Col1a1, Rankl, and Tnf-α of the bone samples was assessed by real-time polymerase chain reaction as a primary outcome. Histological analysis of H&E-stained sections, immunohistochemistry for OPN quantification, and CBCT-based bone tissue examination were performed to investigate the bone healing effects of DBB and FDBA substitutes.Results: The FDBA treated group showed higher gene expression when compared with the DBB treated group in Opn (2.83 ± 1.23 vs. 1.40 ± 0.69; p = 0.04), Runx2 (1.49 ± 0.44 vs. 0.67 ± 0.14; p = 0.01), and Rankl (2.34 ± 0.85 vs. 0.69 ± 0.39; p = 0.03). In the DBB treated group a downregulated expression was found of Ocn relative to maxillary edentulous bone (1.18 ± 0.40 vs. 2.51 ± 0.78; p = 0.02). Conclusion:Two-stage maxillary sinus augmentation with FDBA upregulated specific bone remodeling genes when compared to DBB. The outcome of gene expression matched with the ones for OPN immunoreactivity, being higher in the FDBA group.FDBA had an expression pattern similar to native bone and showed stronger expression of bone forming related-genes suggesting it may be clinically preferable over DBB. This clinical trial was not registered prior to participant recruitment and randomization (clinical registration number TCTR20221217002).