Low‐intensity pulsed ultrasound promotes the formation of periodontal ligament stem cell sheets and ectopic periodontal tissue regeneration

Abstract

Human periodontal ligament stem cells (hPDLSCs) sheets play an important role in periodontal tissue engineering. Low‐intensity pulsed ultrasound (LIPUS) has been reported as an effective stimulus to regulate cell biological behavior. The present study aims to explore the potential of LIPUS to promote the formation and function of hPDLSC sheets (hPDLSCSs). Hematoxylin–eosin (H&E) staining, western blot, real‐time PCR, alkaline phosphatase (ALP), and alizarin red staining were used to evaluate the formation and osteogenic effect of LIPUS on hPDLSCSs in vitro. Hydroxyapatite with or without hPDLSCSs was transplanted in the subcutaneous pockets on the back of nude mice and histological analysis was performed. H&E staining showed increased synthesis of extracellular matrix (ECM) and real‐time PCR detected a significant increase in ECM‐related genes after LIPUS treatment. In addition, LIPUS could promote the expression of osteogenic differentiation‐related genes and proteins. ALP and alizarin red staining also found LIPUS enhanced the osteogenesis of hPDLSCSs. After transplantation in vivo, more dense collagen fibers similar to periodontal ligament were regenerated. Collectively, these results indicate that LIPUS not only promotes the formation and osteogenic differentiation of hPDLSCSs but also is a potential treatment strategy for periodontal tissue engineering.

Low-intensity pulsed ultrasound enhances immunomodulation and facilitates osteogenesis of human periodontal ligament stem cells by inhibiting the NF-κB pathway

“…Previous literature determines 120 mW/cm 2 as high intensity pulsed ultrasound, and the range of LIPUS is less than 100 mW/cm 2 (Saito et al 2004 ). Most studies have clarified the effects of LIPUS on hPDLSCs (Li et al 2020a ; Li et al 2021 ). LIPUS can stimulate the viability and differentiation of hematopoietic stem/progenitor cells in peripheral blood leukocytes (Xu et al 2012 ).…”

“…Additionally, stimulating autophagy could partially restore the osteogenic potential of hPDLSCs, possibly conferring a reference for periodontal tissue regeneration (Kuang et al 2020 ). Elevated expression of inflammatory factors hinders the osteogenesis of hPDLSCs, and LIPUS could reduce LPS-induced inflammation in hPDLSCs (Li et al 2020a ). LIPUS enhances BMP9-induced osteogenesis and represses inflammatory responses of hPDLSCs (Kusuyama et al 2017 ).…”

“…After cells were seeded for 24 h, hPDLSCs were stimulated with LIPUS at intensities of 30, 60, and 90 mW/cm 2 in a water bath maintained at 37 °C for 7 days (30 min/day). The frequency of applied LIPUS was 1.5 MHz, pulse duty cycle was 1:4, and pulse repetition rate was 1.0 kHz, as described previously (Li et al 2020a ; Wang et al 2018a ). hPDLSCs stimulated by LIPUS were co-cultured with PBMCs at a ratio of 1:1 in Transwell chambers (3 × 10 5 cells/well) (Demircan et al 2011 ), and PBMCs were seeded on top of hPDLSCs.…”

“…Inhibition of the NF-κB pathway contributes to periodontal tissue repair in a rat model of periodontitis (Li et al 2020b ). The critical role of LIPUS in the formation of hPDLSC membrane has been unveiled (Kusuyama et al 2019 ; Kusuyama et al 2017 ; Li et al 2021 ; Wang et al 2018a ), whether LIPUS can affect the osteogenic differentiation of hPDLSCs by regulating the NF-κB signaling pathway remains unknown. Therefore, this study focuses on the effect of LIPUS on the NF-κB signaling pathway, which includes some innovative contents.…”

From the Matrix to the Nucleus and Back: Mechanobiology in the Light of Health, Pathologies, and Regeneration of Oral Periodontal Tissues

“…Upon stimulation of PDLCs via LIPUS, osteogenesis in the alveolar region and ECM regeneration was observed [332]. Although not directly shown, it is conceivable that these adaptation processes are mediated through MT signaling pathways [333]. The endoplasmic reticulum unfolded protein response (ER-UPR) as well as autophagic pathways, as detected by an increase in LC3 and Beclin-1 expression, are molecularly involved in the regulation of PDLCs behavior under inflammatory conditions [328,334].…”