Low intensity pulsed ultrasound reduces alveolar bone resorption via mediating cytoskeleton-Lamin A/C-YAP axis of MSCs

Objectives: Orthodontic treatment often requires a long duration and leads to alveolar bone resorption. The effect of low-intensity pulsed ultrasound (LIPUS) on alveolar bone remodeling during orthodontic treatment is still unclear. This study aimed to investigate the impact and mechanism of LIPUS on alveolar bone remodeling during orthodontic tooth movement (OTM) to provide a foundation for clinical application. Materials and methods: We established the rat model of OTM and evaluated the tooth movement rate and alveolar bone remodeling by micro-CT and immunohistochemical staining. In vitro, we isolated human bone marrow mesenchymal stem cells (hBMSCs) and detected osteogenic differentiation ability under compression and LIPUS stimulation by qRT-PCR, Western blot, ALP staining, Alizarin red staining and immunofluorescence staining. Results: Compression force inhibited the osteogenesis of hBMSCs, and the expression of osteogenesis markers decreased, while LIPUS rescued them via modulating YAP1 expression mediated by actin cytoskeleton. In vivo, low-intensity pulsed ultrasound increased alveolar bone density and decreased vertical bone absorption while accelerating orthodontic tooth movement progress. Conclusions: Low-intensity pulsed ultrasound can accelerate tooth movement and reduce the decline of alveolar bone vertical height and bone density by modulating cytoskeleton-Lamin A/C-YAP axis, which is conducive to the stability of alveolar bone during orthodontic process.