Abstract
Background: The oral cavity is a complex environment in which periodontal tissue is constantly stimulated by external microorganisms and mechanical forces. Proper mechanical force helps maintain periodontal tissue homeostasis and improper inflammatory response can break the balance. Periodontal ligament (PDL) cells plays crucial roles in responding these challenges and maintaining the homeostasis of periodontal tissue. However, the mechanisms underlying PDL cell property changes induced by inflammatory and mechanical force microenvironments are still unclear. Recent studies have shown that exosomes function as a mean of cell-cell and cell-matrix communication in biological processes. Methods: Human periodontal ligament stem cells (HPDLSCs) were tested by the CCK8 assay, EdU, alizarin red and ALP staining to evaluate the functions of exosomes induced by mechanical strain. MicroRNA sequencing was used to find the discrepancy miRNA in exosomes. In addition, RT-PCR, FISH, luciferase reporter assay and western blotting assay were used to investigated the mechanism of miR-181b-5p regulating proliferation and osteogenic differentiation through the PTEN/AKT pathway. Results: In this study, the exosomes secreted by MLO-Y4 cells exposed to mechanical strain (Exosome-MS) contributed to human periodontal ligament stem cell (HPDLSC) proliferation and osteogenic differentiation. High-throughput miRNA sequencing showed that miR181b-5p was upregulated in Exosome-MS compared to the exosomes derived from MLO-Y4 cells lacking MS. The luciferase reporter assay demonstrated that miR-181b-5p may target Phosphatase tension homolog deletion (PTEN). In addition, PTEN was negatively regulated by overexpressing miR-181b-5p. PCR and western blot analyses verified that miR‐181b-5p enhanced the protein kinase B (AKT) activity and improved downstream factor transcription. Furthermore, miR-181b-5p effectively ameliorated the inhibition of HPDLSC proliferation and osteogenesis induced by inflammation. Conclusions: This study concluded that exosomes induced by mechanical strain promote HPDLSC proliferation and osteogenic differentiation via the miR-181b-5p/PTEN/AKT signaling pathway, suggesting a potential mechanism for maintaining periodontal homeostasis.
Bone repair by periodontal ligament stem cell-seeded nanohydroxyapatite-chitosan scaffold
