Compressive Force Affects Matrix-Regulatory Molecule Expression Of Periodontal Ligament Cells

Objectives: Periodontal ligament is subjected to the transmitted occlusal force from teeth. However, the roles of intermittent compressive force (ICF) on extracellular matrix (ECM) homeostasis of human periodontal ligament cells (hPDLCs) have not been clarified. The degradation of ECM is controlled by proteolytic enzymes, matrix metalloproteinases (MMPs), on the other hand, the activity of MMP is inhibited by their inhibitor, Tissue Inhibitor of Metalloproteinases (TIMPs). Therefore, this study aims to evaluate the effect of ICF on the expression of MMPs and TIMPs by hPDLCs.
Methods: The hPDLCs were seeded into a 6-well plate with a density of 300,000 cells/well using a growth medium for a day. Then, the medium was changed into a serum-free medium prior to the ICF application. The ICF was applied by adding the six cylinders to the plate and placing it inside the ICF machine, which was connected to a computerized program, with a magnitude of 1.5 g/cm2 and loaded for 24 hours. The mRNA and protein expression of MMPs and TIMPs were assessed using RT-PCR and ELISA analyses, respectively. TGF-β inhibitor (SB431542) was used to assess role of TGF-β in this study. The control was cultured in the same conditions without ICF.
Results: The mRNA and protein levels showed that ICF significantly induces the expression of TIMP1, and TIMP3, but decreases the expression of MMP1 compared to the control group. Treatment with the TGF-β inhibitor and continue loading to ICF showed the downregulation of TIMP3 and TIMP1, however, TGF-β has no effect on the expression of MMP1.
Conclusions: ICF affects ECM homeostasis of hPDLCs by regulating MMPs and TIMPs, furthermore, the expression of TIMP1 and TIMP3 was regulated by TGF-β1. These findings provide an understanding of the molecular mechanism of hPDLCs under ICF and may be beneficial for periodontal regenerative therapy.