Physiological occlusal force constitutively exists in the oral environment and is important for periodontal homeostasis and remodeling. Cyclic tensile stress (CTS) triggers the biological response of periodontal ligament (PDL). However, a few reports have studied the correlation between CTS during physiological occlusal force and PDL cell activities such as osteogenic differentiation. In the present study, human PDL cells (hPDLCs) were subjected to 10% elongation CTS loading at 0.5 Hz for 24 h, which represents the physiological conditions of occlusal force. Gene expression microarray was used to investigate the mechano-induced differential gene profile and pathway analysis in vitro. The osteogenic relative factors, that is, SPP1, RUNX2, and SP7, were assessed by real-time PCR and Western blot. The involvement of mitogen-activated protein kinase (MAPK) signaling pathways was investigated by Western blot with a specific inhibitor. The expressions of SPP1, RUNX2, SP7, p-ERK1/2, and p-Elk1 were up-regulated after 10% CTS exposure. However, these up-regulated expressions were prevented by ERK1/2 inhibitor U0126 in the physiological occlusal force-applied hPDLCs. These results showed that 10% CTS could enhance osteogenic differentiation of hPDLCs via ERK1/2-Elk1 MAPK pathway, indicating that CTS during physiological occlusal force is a potent agent for PDL remodeling.
Hypoxia regulates CTS-responsive changes in proliferation and osteogenic differentiation of hPDLCs via MAPK pathways. Hypoxia-treated hPDLCs may serve as an in vitro model to explore the molecular mechanisms of periodontitis.
Biopolymer nanofiber
membranes are attracting interest as promising
biomaterial scaffolds with a remarkable range of structural and functional
performances for guided bone regeneration (GBR). In this study, tussah
silk nanofiber (TSn) and
Bombyx mori
silk nanofiber (BSn) membranes were prepared by physical shearing.
The diameters of the TSn and BSn membranes were 146.09 ± 63.56
and 120.99 ± 91.32 nm, respectively. TSn showed a Young’s
modulus of 3.61 ± 0.64 GPa and a tensile strength of 74.27 ±
5.19 MPa, which were superior to those of BSn, with a Young’s
modulus of 0.16 ± 0.03 GPa and a tensile strength of 4.86 ±
0.61 MPa. The potential of TSn and BSn membranes to guide bone regeneration
was explored. In vitro, the TSn membrane exhibited significantly higher
cell proliferation for MC3T3-E1 cells than the BSn membrane. In a
cranial bone defect in a rat model, the TSn and BSn membranes displayed
superior bone regeneration compared to the control because the membrane
prevented the ingrowth of soft tissue to the defective area. Compared
to the BSn membrane, the TSn membrane improved damaged bone regeneration,
presumably due to its superior mechanical properties, high osteoconductivity,
and increased cell proliferation. The TSn membrane has a bionic structure,
excellent mechanical properties, and greater biocompatibility, making
it an ideal candidate for GBR.
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