Low‑intensity pulsed ultrasound promotes periodontal ligament stem cell migration through TWIST1‑mediated SDF‑1 expression.

Abstract

Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapeutic treatment for accelerating fracture healing. A previous study from our group demonstrated that LIPUS has the potential to promote periodontal tissue regeneration. However, the underlying molecular mechanism by which LIPUS promotes periodontal tissue regeneration remains unknown. In the present study, periodontal ligament stem cells (PDLSCs) were isolated from premolars. Flow cytometry and differentiation assays were used to characterize the isolated PDLSCs. LIPUS treatment was administered to PDLSCs, and stromal cell-derived factor-1 (SDF-1) expression levels were examined by reverse transcription-quantitative polymerase chain reaction with or without blocking the SDF-1/C-X-C motif chemokine receptor 4 (CXCR4) pathway with AMD3100. ELISA was used to evaluate SDF-1 secretion in PDLSCs. Wound healing and transwell assays were conducted to assess the migration-promoting effect of LIPUS. A potential upstream gene of SDF-1, twist family bHLH transcription factor 1 (TWIST1), was silenced by small interfering (si) RNA transfection. The results demonstrated that LIPUS treatment promoted the expression of TWIST1 and SDF-1 at both the mRNA and protein levels. In addition, LIPUS treatment enhanced the cell migration of PDLSCs. Knockdown of TWIST1 impaired the expression of SDF-1 and the cell migration ability of PDLSCs. TWIST1 may be an upstream regulator of SDF-1 in PDLSCs. Taken together, these findings indicate that the SDF1/CXCR4 signaling pathway is involved in LIPUS-promoted PDLSC migration, which might be one of the mechanisms for LIPUS-mediated periodontal regeneration. TWIST1 might be a mechanical stress sensor during mechanotransduction.