LIPUS inhibited the expression of inflammatory factors and promoted the osteogenic differentiation capacity of hPDLCs by inhibiting the NF-κB signaling pathway

The role of NF-kappaB in the inflammatory processes related to dental caries, pulpitis, apical periodontitis, and periodontitis-a narrative review

Tooth-related inflammatory disorders, including caries, pulpitis, apical periodontitis (AP), and periodontitis (PD), are primarily caused by resident oral microorganisms. Although these dental inflammatory conditions are typically not life-threatening, neglecting them can result in significant complications and greatly reduce an individual's quality of life. Nuclear factor κB (NF-κB), a family formed by various combinations of Rel proteins, is extensively involved in inflammatory diseases and even cancer. This study reviews recent data on NF-κB signaling and its role in dental pulp stem cells (DPSCs), dental pulp fibroblasts (DPFs), odontoblasts, human periodontal ligament cells (hPDLCs), and various experimental animal models. The findings indicate that NF-κB signaling is abnormally activated in caries, pulpitis, AP, and PD, leading to changes in related cellular differentiation. Under specific conditions, NF-κB signaling occasionally interacts with other signaling pathways, affecting inflammation, bone metabolism, and tissue regeneration processes. In summary, data collected over recent years confirm the central role of NF-κB in dental inflammatory diseases, potentially providing new insights for drug development targeting NF-κB signaling pathways in the treatment of these conditions. Keywords: NF-κB, dental caries, pulpitis, apical periodontitis, periodontitis.

Focused ultrasound-induced cell apoptosis for the treatment of tumours

Cancer is a serious public health problem worldwide. Traditional treatments, such as surgery, radiotherapy, chemotherapy, and immunotherapy, do not always yield satisfactory results; therefore, an efficient treatment for tumours is urgently needed. As a convenient and minimally invasive modality, focused ultrasound (FUS) has been used not only as a diagnostic tool but also as a therapeutic tool in an increasing number of studies. FUS can help treat malignant tumours by inducing apoptosis. This review describes the three apoptotic pathways, apoptotic cell clearance, and how FUS affects these three apoptotic pathways. This review also discusses the role of thermal and cavitation effects on apoptosis, including caspase activity, mitochondrial dysfunction, and Ca2+ elease. Finally, this article reviews various aspects of FUS combination therapy, including sensitization by radiotherapy and chemotherapy, gene expression upregulation, and the introduction of therapeutic gases, to provide new ideas for clinical tumour therapy.

Mitochondria-targeted sonodynamic modulation of neuroinflammation to protect against myocardial ischemia‒reperfusion injury

Sympathetic hyperactivation and inflammatory responses are the main causes of myocardial ischemia‒reperfusion (I/R) injury and myocardial I/R-related ventricular arrhythmias (VAs). Previous studies have demonstrated that light-emitting diodes (LEDs) could modulate post-I/R neuroinflammation, thus providing protection against myocardial I/R injury. Nevertheless, further applications of LEDs are constrained due to the low penetration depth (<1 cm) and potential phototoxicity. Low-intensity focused ultrasound (LIFU), an emerging noninvasive neuromodulation strategy with deeper penetration depth (∼10 cm), has been confirmed to modulate sympathetic nerve activity and inflammatory responses. Sonodynamic therapy (SDT), which combines LIFU with sonosensitizers, confers additional advantages, including superior therapeutic efficacy, precise localization of neuronal modulation and negligible side effects. Herein, LIFU and SDT were introduced to modulate post-myocardial I/R neuroinflammation to protect against myocardial I/R injury. The results indicated that LIFU and SDT inhibited sympathetic neural activity, suppressed the activation of astrocytes and microglia, and promoted microglial polarization towards the M2 phenotype, thereby attenuating myocardial I/R injury and preventing I/R-related malignant VAs. These insights suggest that LIFU and SDT inspire a noninvasive and efficient neuroinflammatory modulation strategy with great clinical translation potential thus benefiting more patients with myocardial I/R in the future. STATEMENT OF SIGNIFICANCE: Myocardial ischemia-reperfusion (I/R) may cause I/R injury and I/R-induced ventricular arrhythmias. Sympathetic hyperactivation and inflammatory response play an adverse effect in myocardial I/R injury. Previous studies have shown that light emitting diode (LED) can regulate I/R-induced neuroinflammation, thus playing a myocardial protective role. However, due to the low penetration depth and potential phototoxicity of LED, it is difficult to achieve clinical translation. Herein, we introduced sonodynamic modulation of neuroinflammation to protect against myocardial I/R injury, based on mitochondria-targeted nanosonosensitizers (CCNU980 NPs). We demonstrated that sonodynamic modulation could promote microglial autophagy, thereby preventing myocardial I/R injury and I/R-induced ventricular arrhythmias. This is the first example of sonodynamic modulation of myocardial I/R-induced neuroinflammation, providing a novel strategy for clinical translation.

Effect of low-intensity pulsed ultrasound on the mineralization of force-treated cementoblasts and orthodontically induced inflammatory root resorption via the Lamin A/C-Yes associated protein axis

AIMS

Orthodontic treatment commonly results in orthodontically induced inflammatory root resorption (OIIRR). This condition arises from excessive orthodontic force, which triggerslocal inflammatory responses and impedes cementoblasts' mineralization capacity. Low-intensity pulsed ultrasound (LIPUS) shows potential in reducing OIIRR. However, the precise mechanisms through which LIPUS reduces OIIRR remain unclear. This study aimed to explore the effects and mechanisms of LIPUS on the mineralization of force-treated cementoblasts and its impact on OIIRR.

METHODS

We established a rat OIIRR model and locally administered LIPUS stimulation for 7 and 14 days. We analyzed root resorption volume, osteoclast differentiation, and the expression of osteocalcin and yes-associated protein 1 (YAP1) using micro-computed tomography (micro-CT), hematoxylin and eosin, tartrate-resistant acid phosphatase, immunofluorescence and immunohistochemistry staining. In vitro, we applied compressive force and LIPUS to the immortalized mouse cementoblasts (OCCM30). We assessed mineralization using alkaline phosphatase (ALP) staining, alizarin red staining, real-time quantitative polymerase chain reaction, Western blotting and immunofluorescence staining.

RESULTS

In rats, LIPUS reduced OIIRR, as evidenced by micro-CT analysis and histological staining. In vitro, LIPUS enhanced mineralization of force-treated OCCM30 cells, as indicated by ALP and alizarin red staining, upregulated mRNA expression of mineralization-related genes, and increased protein expression of mineralization markers. Mechanistically, LIPUS activated YAP1 signaling via the cytoskeleton-Lamin A/C pathway, supported by immunofluorescence and Western blot analysis.

CONCLUSION

This study demonstrates that LIPUS promotes mineralization in force-treated cementoblasts and reduces OIIRR by activating YAP1 through the cytoskeletal-Lamin A/C signaling pathway. These findings provide fresh insights into how LIPUS benefits orthodontic treatment and suggest potential strategies for preventing and treating OIIRR.

Low-Intensity Pulsed Ultrasound: A Physical Stimulus with Immunomodulatory and Anti-inflammatory Potential

Ultrasound has expanded into the therapeutic field as a medical imaging and diagnostic technique. Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound that plays a vital role in promoting fracture healing, wound repair, immunomodulation, and reducing inflammation. Its anti-inflammatory effects are manifested by decreased pro-inflammatory cytokines and chemokines, accelerated regression of immune cell invasion, and accelerated damage repair. Although the anti-inflammatory mechanism of LIPUS is not very clear, many in vitro and in vivo studies have shown that LIPUS may play its anti-inflammatory role by activating signaling pathways such as integrin/Focal adhesion kinase (FAK)/Phosphatidylinositol 3-kinase (PI3K)/Serine threonine kinase (Akt), Vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), or inhibiting signaling pathways such as Toll-like receptors (TLRs)/Nuclear factor kappa-B (NF-κB) and p38-Mitogen-activated protein kinase (MAPK). As a non-invasive physical therapy, the anti-inflammatory and immunomodulatory effects of LIPUS deserve further exploration.

LIPUS can promote osteogenesis of hPDLCs and inhibit the periodontal inflammatory response via TLR5

In this study, we isolated human periodontal ligament cells (hPDLCs) to find the optimal time of LIPUS stimulation and to explore how LIPUS affects inflammatory and osteogenic responses in hPDLCs in an inflammatory environment. The target molecules of LIPUS were identified by high-throughput sequencing. RT-qPCR and WB were used to detect how LIPUS affected the expression of related genes in TNFα-induced inflammation. The expression of ROS and inflammatory factors was detected by flow cytometry. Immunohistochemistry was used to further verify gene expression in rats. hPDLCs were isolated successfully. The optimal LIPUS stimulation condition was 45 mW/cm2 for 30 min and continued for 3 days, and this intensity significantly promoted the osteogenesis and mineralization of hPDLCs. LIPUS significantly inhibited the upregulation of IL-6 and ROS, increased the percentage of cells in the G2 phase, inhibited cell apoptosis, and inhibited the upregulation of TLR5 expression in an inflammatory environment. LIPUS can effectively restrain the inflammation and oxidative stress response of hPDLCs and promote osteogenesis in an inflammatory environment. LIPUS inhibited the periodontal inflammatory response through TLR5 in hPDLCs and dental pulp.

Diosgenin prevents periodontitis by inhibiting inflammation and promoting osteogenic differentiation

Diosgenin, an essential dietary steroidal sapogenin, possess multiple pharmacological activities. This study aimed to assess the effects of diosgenin on periodontitis and elucidate the mechanisms. Lipopolysaccharide (LPS)-stimulated human periodontal ligament stem cells (hPDLCs) and a Porphyromonas gingivalis (P.g) plus ligation-induced animal model were used for in vitro and in vivo studies, respectively. Inflammatory responses, nuclear factor κ-B (NF-κB) signaling and osteogenesis-related markers were measured both in LPS-stimulated hPDLSCs and in gingival tissue of periodontitis rats. Treatment with diosgenin significantly inhibited the production of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and interleukin (IL)-6 and the activation of NF-κB pathway in LPS-stimulated hPDLSCs. Further, treatment with diosgenin enhanced the expression of osteoblast-related genes and increased the osteogenic differentiation capacity. Further, activation NF-κB pathway largely abolished the protective effects of diosgenin. Consistent with the in vitro studies, in vivo studies showed that administering diosgenin to periodontitis rats significantly lowered the levels of the TNF-α, IL-1β, and IL-6 and the inflammatory transcription factor NF-κB in gingival tissue. In addition, osteoblast-related genes were promoted. Diosgenin attenuates periodontitis by adjusting NF-κB signaling to inhibit inflammatory effects and promoting osteogenesis, suggesting diosgenin might be developed as a therapeutic strategy for treating periodontitis in the future.

Developmental endothelial locus-1 promotes osteogenic differentiation and alveolar bone regeneration in experimental periodontitis with type 2 diabetes mellitus

OBJECTIVES

This study sought to explore the role of developmental endothelial locus-1 (DEL-1) in osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and investigate the therapeutic effect of DEL-1 in ligature-induced experimental periodontitis with type 2 diabetes mellitus (T2DM).

BACKGROUND

T2DM is a significant risk factor for periodontitis. Treatment modalities for periodontitis with T2DM are being explored. DEL-1 is a versatile protein that can modulate the different stages of inflammatory diseases including periodontitis. The direct effect of DEL-1 on osteogenic differentiation of PDLSCs in periodontitis with T2DM is poorly understood.

METHODS

Primary hPDLSCs were isolated from periodontal ligament tissue and identified by flow cytometry. In osteogenesis experiments, alkaline phosphatase (ALP), Alizarin Red staining and western blot were used to assess the osteogenic effect of DEL-1 on hPDLSCs in high glucose and inflammation environments. The mouse model of ligature-induced experimental periodontitis was established. H&E and Masson's trichrome staining were used to assess the change of periodontal tissue after local periodontal injection of DEL-1. Immunohistochemical staining was used to evaluate osteogenic-related protein expression.

RESULTS

hPDLSCs expressed mesenchymal stem cell (MSC)-specific surface markers and were negative for hematopoietic cell surface markers. hPDLSCs had the potential for multidirectional differentiation. DEL-1 could enhance the osteogenic differentiation of hPDLSCs in high glucose and inflammation environments, although it did not return to the control level. Histological staining showed that DEL-1 contributed to alveolar bone regeneration and osteogenic-related protein expression, but the degree of improvement in T2DM mice was lower than in non-T2DM mice.

CONCLUSIONS

In summary, we demonstrated that DEL-1 could promote osteogenic differentiation of hPDLSCs in high glucose and inflammation environment and rescue alveolar bone loss in experimental periodontitis with T2DM, which could provide a novel therapeutic target for periodontitis with T2DM.

Influence of Ultrasound Stimulation on the Viability, Proliferation and Protein Expression of Osteoblasts and Periodontal Ligament Fibroblasts

Among the adjunctive procedures to accelerate orthodontic tooth movement (OTM), ultrasound (US) is a nonsurgical form of mechanical stimulus that has been explored as an alternative to the currently available treatments. This study aimed to clarify the role of US in OTM by exploring different stimulation parameters and their effects on the biological responses of cells involved in OTM. Human fetal osteoblasts and periodontal ligament fibroblasts cell lines were stimulated with US at 1.0 and 1.5 MHz central frequencies and power densities of 30 and 60 mW/cm2 in continuous mode for 5 and 10 min. Cellular proliferation, metabolic activity and protein expression were analyzed. The US parameters that significantly improved the metabolic activity were 1.0 MHz at 30 mW/cm2 for 5 min and 1.0 MHz at 60 mW/cm2 for 5 and 10 min for osteoblasts; and 1.0 MHz at 30 mW/cm2 for 5 min and 1.5 MHz at 60 mW/cm2 for 5 and 10 min for fibroblasts. By stimulating with these parameters, the expression of alkaline phosphatase was maintained, while osteoprotegerin synthesis was induced after three days of US stimulation. The US stimulation improved the biological activity of both osteoblasts and periodontal ligament fibroblasts, inducing their osteogenic differentiation.

Evaluate the effects of low-intensity pulsed ultrasound on dental implant osseointegration under type II diabetes

Objective: The objective of this study is to assess the impact of low-intensity pulsed ultrasound (LIPUS) therapy on the peri-implant osteogenesis in a Type II diabetes mellitus (T2DM) rat model. Methods: A total of twenty male Sprague-Dawley (SD) rats were randomly allocated into four groups: Control group, T2DM group, Control-LIPUS group, and T2DM-LIPUS group. Implants were placed at the rats' bilateral maxillary first molar sites. The LIPUS treatment was carried out on the rats in Control-LIPUS group and T2DM-LIPUS group, immediately after the placement of the implants, over three consecutive weeks. Three weeks after implantation, the rats' maxillae were extracted for micro-CT, removal torque value (RTV), and histologic analysis. Results: Micro-CT analysis showed that T2DM rats experienced more bone loss around implant cervical margins compared with the non-T2DM rats, while the LIPUS treated T2DM rats showed similar bone heights to the non-T2DM rats. Bone-implant contact ratio (BIC) were lower in T2DM rats but significantly improved in the LIPUS treated T2DM rats. Bone formation parameters including bone volume fraction (BV/TV), trabecular thickness (Tb.Th), bone mineral density (BMD) and RTV were all positively influenced by LIPUS treatment. Histological staining further confirmed LIPUS's positive effects on peri-implant new bone formation in T2DM rats. Conclusion: As an effective and safe treatment in promoting osteogenesis, LIPUS has a great potential for T2DM patients to attain improved peri-implant osteogenesis. To confirm its clinical efficacy and to explore the underlying mechanism, further prospective cohort studies or randomized controlled trials are needed in the future.

Low intensity pulsed ultrasound ameliorates Adriamycin-induced chronic renal injury by inhibiting ferroptosis

OBJECTIVE

It is very important to develop a new therapeutic strategy to cope with the increasing morbidity and mortality of chronic kidney disease (CKD). As a kind of physical therapy, low intensity pulsed ultrasound (LIPUS) has remarkable anti-inflammatory and repair-promoting effects and is expected to become a new therapeutic method for CKD. This study aims to clarify the treatment effect of LIPUS on CKD-related renal inflammation and fibrosis, and to further explore the potential signal network of LIPUS treatment for ameliorating chronic renal injury.

METHODS

A rat model simulating the progress of CKD was established by twice tail-vein injection of Adriamycin (ADR). Under anesthesia, bilateral kidneys of CKD rats were continuously stimulated by LIPUS for four weeks. The parameters of LIPUS were 1.0 MHz, 60 mW/cm2, 50% duty cycle and 20 min/d.

RESULTS

LIPUS treatment effectively inhibited ADR-induced renal inflammation and fibrosis, and improved CKD-related to oxidative stress and ferroptosis. In addition, the therapeutic effect of LIPUS is closely related to the regulation of TGF-β1/Smad and Nrf2/keap1/HO-1 signalling pathways.

DISCUSSION

This study provides a new direction for further mechanism research and lays an important foundation for clinical trials.

Transcriptome profile analysis revealed the potential mechanism of LIPUS treatment for Adriamycin-induced chronic kidney disease rat

Background

Developing effective therapeutic strategies to delay the progression of chronic kidney disease (CKD) remains a significant challenge. Low-intensity pulsed ultrasound (LIPUS) has demonstrated potential for treating CKD, but the underlying molecular mechanisms are still elusive. This study aimed to evaluate the therapeutic efficacy of LIPUS and to elucidate the involved genes and signaling pathways.

Methods

The CKD model was established in rats using Adriamycin (ADR). The bilateral kidneys of CKD rats were continuously stimulated with LIPUS for a period of four weeks. The therapeutic efficacy was defined by renal function and histopathological evaluation. RNA sequencing was employed to profile the transcriptome of rat kidneys in each group. Cluster analysis was utilized to identify differentially expressed genes (DEGs), followed by enrichment analysis of their associated pathways using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases.

Results

LIPUS treatment improved ADR-induced renal dysfunction in the CKD group. Renal fibrosis and pathological damages were also alleviated in the ADR + LIPUS group compared to the ADR group. Cluster analysis identified 844 DEGs. GO enrichment analysis revealed enrichment in inflammatory response terms, while KEGG enrichment analysis highlighted the nuclear factor kappa B (NF-κB) signaling and ferroptosis-related pathways.

Conclusion

Continuous LIPUS treatment improved ADR-induced renal fibrosis and dysfunction. The therapeutic effect of LIPUS was primarily due to its ability to suppress the CKD-related inflammation, which was associated with the modulation of the NF-κB and ferroptosis signaling pathways. These findings provide a new insight into the potential molecular mechanisms of LIPUS in treating CKD. Further research is necessary to confirm these findings and to identify potential therapeutic targets within these pathways.

A Bibliometric Analysis for Low-Intensity Ultrasound Study Over the Past Three Decades

Low-intensity ultrasound (LI-US) is a non-invasive stimulation technique that has emerged in recent years and has been shown to have positive effects on neuromodulation, fracture healing, inflammation improvement, and metabolic regulation. This study reports the conclusions of a bibliometric analysis of LI-US. Input data for the period between 1995 and 2022, including 7209 related articles in the field of LI-US, were collected from the core library of the Web of Science (WOS) database. Using these data, a set of bibliometric indicators was obtained to gain knowledge on different aspects: global production, research areas, and sources analysis, contributions of countries and institutions, author analysis, citation analysis, and keyword analysis. This study combined the data analysis capabilities provided by the WOS database, making use of two bibliometric software tools: R software and VOS viewer to achieve analysis and data exploration visualization, and predicted the further development trends of LI-US. It turns out that the United States and China are co-leaders while Zhang ZG is the most significant author in LI-US. In the future, the hot spots of LI-US will continue to focus on parameter research, mechanism discussion, safety regulations, and neuromodulation applications.

LIPUS-S/B@NPs regulates the release of SDF-1 and BMP-2 to promote stem cell recruitment-osteogenesis for periodontal bone regeneration

Purpose: Poly (lactic-co-glycolic acid)-based nanoparticles (PLGA NPs) have been widely used as the carrier for sustainable drug delivery. However, the drug release from the NPs was usually incomplete and uncontrollable. Herein, a low intensity pulsed ultrasound (LIPUS) assisted SDF-1/BMP-2@nanoparticles (S/B@NPs) system was fabricated to facilitate stem cell recruitment-osteogenesis for periodontal bone regeneration. Methods: In this work, S/B@NPs were prepared with double-emulsion synthesis method. Then the S/B release profile from NPs was evaluated with or without low intensity pulsed ultrasound treatment. Afterwards, the stem cell recruiting and osteoinductive capacities of LIPUS-S/B@NPs were detected with human periodontal ligament cells (hPDLCs) in vitro and in a rat periodontal bone defect model. Results: The results indicated that S/B@NPs were successfully prepared and LIPUS could effectively regulate the release of S/B and increase their final releasing amount. Moreover, LIPUS-S/B@NPs system significantly promoted hPDLCs migrating and osteogenesis in vitro and recruiting rBMSCs to the rat periodontal defect and facilitated bone regeneration in vivo. Conclusion: Our LIPUS assisted S/B@NPs system can effectively facilitate stem cell recruitment and periodontal bone regeneration. Considering its reliable safety and therapeutic effect on bone fracture, LIPUS, as an adjuvant therapy, holds great potential in the regulation of drug delivery systems for bone healing.

Low-Intensity Pulsed Ultrasound Attenuates Periodontal Ligament Cells Apoptosis by Activating Yes-Associated Protein-Regulated Autophagy

OBJECTIVE

The goal of the work described here was to determine if low-intensity pulsed ultrasound (LIPUS) has an anti-inflammatory effect on lipopolysaccharide (LPS)-induced inflammation in periodontal ligament cells (PDLCs). The mechanism underlying this effect remains to be explored and is likely related to PDLC apoptosis regulated by Yes-associated protein (YAP) and autophagy.

METHODS

To verify this hypothesis, we used a rat model of periodontitis and primary human PDLCs. We examined alveolar bone resorption in rats and apoptosis, autophagy and YAP activity in LPS-treated PDLCs with and without application of LIPUS by cellular immunofluorescence, transmission electron microscopy and Western blotting. Then, siRNA transfection was used to decrease YAP expression to confirm the regulatory role of YAP in the anti-apoptotic effect of LIPUS on PDLCs.

DISCUSSION

We found that LIPUS attenuated alveolar bone resorption in rats and this was accompanied by YAP activation. LIPUS inhibited hPDLC apoptosis by YAP activation, and promoted autophagic degradation to help autophagy completion. These effects were reversed after YAP expression was blocked.

CONCLUSION

LIPUS attenuates PDLC apoptosis by activating Yes-associated protein-regulated autophagy.

Low-intensity pulsed ultrasound promotes mesenchymal stem cell transplantation-based articular cartilage regeneration via inhibiting the TNF signaling pathway

BACKGROUND

Mesenchymal stem cell (MSC) transplantation therapy is highly investigated for the regenerative repair of cartilage defects. Low-intensity pulsed ultrasound (LIPUS) has the potential to promote chondrogenic differentiation of MSCs. However, its underlying mechanism remains unclear. Here, we investigated the promoting effects and mechanisms underlying LIPUS stimulation on the chondrogenic differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) and further evaluated its regenerative application value in articular cartilage defects in rats.

METHODS

LIPUS was applied to stimulate cultured hUC-MSCs and C28/I2 cells in vitro. Immunofluorescence staining, qPCR analysis, and transcriptome sequencing were used to detect mature cartilage-related markers of gene and protein expression for a comprehensive evaluation of differentiation. Injured articular cartilage rat models were established for further hUC-MSC transplantation and LIPUS stimulation in vivo. Histopathology and H&E staining were used to evaluate the repair effects of the injured articular cartilage with LIPUS stimulation.

RESULTS

The results showed that LIPUS stimulation with specific parameters effectively promoted the expression of mature cartilage-related genes and proteins, inhibited TNF-α gene expression in hUC-MSCs, and exhibited anti-inflammation in C28/I2 cells. In addition, the articular cartilage defects of rats were significantly repaired after hUC-MSC transplantation and LIPUS stimulation.

CONCLUSIONS

Taken together, LIPUS stimulation could realize articular cartilage regeneration based on hUC-MSC transplantation due to the inhibition of the TNF signaling pathway, which is of clinical value for the relief of osteoarthritis.

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

Human periodontal ligament stem cells (hPDLSCs) are vital in cellular regeneration and tissue repair due to their multilineage differentiation potential. Low intensity pulsed ultrasound (LIPUS) has been applied for treating bone and cartilage defects. This study explored the role of LIPUS in the immunomodulation and osteogenesis of hPDLSCs. hPDLSCs were cultured in vitro, and the effect of different intensities of LIPUS (30, 60, and 90 mW/cm²) on hPDLSC viability was measured. hPDLSCs irradiated by LIPUS and stimulated by lipopolysaccharide (LPS) and LIPUS (90 mW/cm2) were co-cultured with peripheral blood mononuclear cells (PBMCs). Levels of immunomodulatory factors in hPDLSCs and inflammatory factors in PBMCs were estimated, along with determination of osteogenesis-related gene expression in LIPUS-irradiated hPDLSCs. The mineralized nodules and alkaline phosphatase (ALP) activity of hPDLSCs and levels of IκBα, p-IκBα, and p65 subunits of NF-κB were determined. hPDLSC viability was increased as LIPUS intensity increased. Immunomodulatory factors were elevated in LIPUS-irradiated hPDLSCs, and inflammatory factors were reduced in PBMCs. Osteogenesis-related genes, mineralized nodules, and ALP activity were promoted in LIPUS-irradiated hPDLSCs. The cytoplasm of hPDLSCs showed increased IκBα and p65 and decreased p-IκBα at increased LIPUS intensity. After LPS and LIPUS treatment, the inhibitory effect of LIPUS irradiation on the NF-κB pathway was partially reversed, and the immunoregulation and osteogenic differentiation of hPDLSCs were decreased. LIPUS irradiation enhanced immunomodulation and osteogenic differentiation abilities of hPDLSCs by inhibiting the NF-κB pathway, and the effect is dose-dependent. This study may offer novel insights relevant to periodontal tissue engineering.

Silibinin Attenuates Experimental Periodontitis by Downregulation of Inflammation and Oxidative Stress

Periodontitis is an oral microbiota-induced inflammatory disease, in which inflammation and oxidative stress play a critical role. Silibinin (SB), a Silybum marianum-derived compound, exhibits strong anti-inflammatory and antioxidative properties. We adopted a rat ligature-induced periodontitis model and a lipopolysaccharide- (LPS-) stimulated human periodontal ligament cells (hPDLCs) model to evaluate the protective effects of SB. In the in vivo model, SB reduced alveolar bone loss and apoptosis of PDLCs in the periodontal tissue. SB also maintained the expression of nuclear factor-E2-related factor 2 (Nrf2), a key regulator of cellular resistance to oxidative stress, and attenuated lipid, protein, and DNA oxidative damages in the periodontal lesion area. Meanwhile, in the in vitro model, SB administration reduced the production of intracellular reactive oxidative species (ROS). Furthermore, SB exerted a strong anti-inflammatory property in both in vivo and in vitro models by inhibiting the expression of inflammatory mediators including nuclear factor-κB (NF-κB) as well as nucleotide binding oligomerization domain- (NOD-) like receptor family pyrin domain-containing 3 (NLRP3) and downregulating the levels of proinflammatory cytokines. This study, for the first time, demonstrates that SB exhibits the anti-inflammatory and antioxidative properties against periodontitis by downregulating the expression of NF-κB and NLRP3 and upregulating Nrf2 expression, suggesting a promising potential clinical application of SB in periodontitis.

LIPUS as a potential strategy for periodontitis treatment: A review of the mechanisms

Periodontitis is a chronic inflammatory condition triggered by oral bacteria. A sustained inflammatory state in periodontitis could eventually destroy the alveolar bone. The key objective of periodontal therapy is to terminate the inflammatory process and reconstruct the periodontal tissues. The traditional Guided tissue regeneration (GTR) procedure has unstable results due to multiple factors such as the inflammatory environment, the immune response caused by the implant, and the operator's technique. Low-intensity pulsed ultrasound (LIPUS), as acoustic energy, transmits the mechanical signals to the target tissue to provide non-invasive physical stimulation. LIPUS has positive effects in promoting bone regeneration, soft-tissue regeneration, inflammation inhibition, and neuromodulation. LIPUS can maintain and regenerate alveolar bone during an inflammatory state by suppressing the expression of inflammatory factors. LIPUS also affects the cellular behavior of periodontal ligament cells (PDLCs), thereby protecting the regenerative potential of bone tissue in an inflammatory state. However, the underlying mechanisms of the LIPUS therapy are still yet to be summarized. The goal of this review is to outline the potential cellular and molecular mechanisms of periodontitis-related LIPUS therapy, as well as to explain how LIPUS manages to transmit mechanical stimulation into the signaling pathway to achieve inflammatory control and periodontal bone regeneration.

Biochemical and Physiological Events Involved in Responses to the Ultrasound Used in Physiotherapy: A Review

Therapeutic ultrasound (TUS) is the ultrasound modality widely used in physical therapy for the treatment of acute and chronic injuries of various biological tissues. Its thermal and mechanical effects modify the permeability of the plasma membrane, the flow of ions and molecules and cell signaling and, in this way, promote the cascade of physiological events that culminate in the repair of injuries. This article is a review of the biochemical and physiological effects of TUS with parameters commonly used by physical therapists. Integrins can translate the mechanical signal of the TUS into a cellular biochemical signal for protein synthesis and modification of the active site of enzymes, so cell function and metabolism are modified. TUS also alters the permeability of the plasma membrane, allowing the influx of ions and molecules that modulate the cellular electrochemical signaling pathways. With biochemical and electrochemical signals tampered with, the cellular response to damage is then modified or enhanced. Greater release of pro-inflammatory factors, cytokines and growth factors, increased blood flow and activation of protein kinases also seem to be involved in the therapeutic response of TUS. Although a vast number of publications describe the mechanisms by which TUS can interact with the biological system, little is known about the metabolic possibilities of TUS because of the lack of standardization in its application.

Immune senescence and periodontitis: From mechanism to therapy

Periodontitis is one of the most prevalent infectious inflammatory diseases, characterized by irreversible destruction of the supporting tissues of teeth, which is correlated with a greater risk of multiple systemic diseases, thus regarded as a major health concern. Dysregulation between periodontal microbial community and host immunity is considered to be the leading cause of periodontitis. Comprehensive studies have unveiled the double-edged role of immune response in the development of periodontitis. Immune senescence, which is described as age-related alterations in immune system, including a diminished immune response to endogenous and exogenous stimuli, a decline in the efficiency of immune protection, and even failure in immunity build-up after vaccination, leads to the increased susceptibility to infection. Recently, the intimate relationship between immune senescence and periodontitis has come into focus, especially in the aging population. In this review, both periodontal immunity and immune senescence will be fully introduced, especially their roles in the pathology and progression of periodontitis. Furthermore, novel immunotherapies targeting immune senescence are presented to provide potential targets for research and clinical intervention in the future.

Low-intensity pulsed ultrasound promotes periodontal regeneration in a beagle model of furcation involvement

Objective: To evaluate the regeneration potential of periodontitis tissue treated by low-intensity pulsed ultrasound (LIPUS) combined with the guided tissue regeneration (GTR) technique in a beagle model of furcation involvement (FI).

Background: Achieving predictable regeneration remains a clinical challenge for periodontitis tissue due to the compromised regenerative potential caused by chronic inflammation stimulation. LIPUS, an FDA-approved therapy for long bone fracture and non-unions, has been demonstrated effective in the in vitro attenuation of inflammation-induced dysfunction of periodontal ligament stem cells (PDLSCs), the key cells contributing to periodontal regeneration. However, the in vivo effect of LIPUS on periodontitis tissue is rarely reported.

Methods: A beagle model of FI was established, and the experimental teeth were randomly assigned into three groups: control group, GTR group, and GTR+LIPUS group. Radiographic examinations were performed, and clinical periodontal parameters were recorded to reflect the periodontal condition of different groups. Histological analyses using H&amp;E and Masson’s staining were conducted to evaluate the periodontal tissue regeneration.

Results: LIPUS could enhance new periodontal bone formation and bone matrix maturity in FI after GTR treatment. Moreover, clinical assessment and histomorphometric analyses revealed less inflammatory infiltration and superior vascularization within bone grafts in the LIPUS treatment group, indicating the anti-inflammatory and pro-angiogenic effects of LIPUS in FI.

Conclusion: Our investigation on a large animal model demonstrated that LIPUS is a promising adjunctive approach for the regeneration of periodontitis tissue, paving a new avenue for LIPUS application in the field of periodontal regenerative medicine.

ANGPTL4 regulates the osteogenic differentiation of periodontal ligament stem cells

The molecular mechanism of mechanical force regulating the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) has not been clearly elucidated. In this study, two mRNA-seqs, GSE106887 and GSE109167, which contained several samples of PDLSCs under mechanical force, were downloaded from Gene Expression Omnibus. Differential expression analysis was firstly taken between GSE106887 and GSE109167, then the common 84 up-regulated genes and 26 down-regulated genes were selected. Function enrichment analysis was used to identify the key genes and pathways in PDLSCs subjected to the tension and compression force. PDLSCs were isolated from human periodontal ligament tissues. The effects of ANGPTL4 knockdown with shRNA on the osteogenic differentiation of PDLSCs were studied in vitro. Then, the orthodontic tooth movement (OTM) rat model was used to study the expression of HIF-1α and ANGPTL4 in alveolar bone remodeling in vivo. ANGPTL4 and the HIF-1 pathway were identified in PDLSCs subjected to the tension and compression force. alizarin red staining, alcian blue staining, and oil red O staining verified that PDLSCs had the ability of osteogenic, chondrogenic, and adipogenic differentiation, respectively. Verification experiment revealed that the expression of ANGPTL4 in PDLSCs significantly increased when cultured under osteogenic medium in vitro. While ANGPTL4 was knocked down by shRNA, the levels of ALPL, RUNX2, and OCN decreased significantly, as well as the protein levels of COL1A1, ALPL, RUNX2, and OCN. During the OTM, the expression of HIF-1α and ANGPTL4 in periodontal ligament cells increased on the tension and compression sides. We concluded the positive relationship between ANGPTL4 and osteogenic differentiation of PDLSCs.

Low-intensity pulsed ultrasound enhances bone marrow-derived stem cells-based periodontal regenerative therapies

BACKGROUND

Alveolar bone loss is one of the most common consequence for periodontitis, which is a major obstacle in periodontal regeneration. Bone marrow stromal cells (BMSCs) have shown significant promise in the treatment of various disease, which also contribute to the natural bone repair process. Low-intensity pulsed ultrasound (LIPUS) is a therapeutic ultrasound used in our previous studies to promotes alveolar bone regeneration. In addition, LIPUS was found to be a promising method to enhance mesenchymal stromal cell-based therapies. In the current study, we have investigated the effects of LIPUS combined with BMSCs therapies on BMSCs homing and its potential to promote alveolar bone regeneration.

METHODS

BMSCs were isolated from rat and characterized by multilineages differentiation assay. Then these cells were labeled with luciferase and green fluorescent protein (GFP) by lentivirus in vitro. Periodontal bone defect was made on the mesial area of the maxillary first molar in rats. A total of 1 × 10⁶ Luc-GFP labeled BMSCs were injected into rat tail vein. Bioluminescence imaging was utilized to track BMSCs in vivo. The rats were sacrificed eight weeks after surgery and the samples were harvested. Micro-computed tomography (Micro-CT) was performed to evaluate alveolar bone regeneration. Paraffin sections were made and subject to hematoxylin-eosin staining, masson staining and immunohistochemistry staining.

RESULTS

BMSCs display a fibroblast-like morphology and can differentiate into adipocytes or osteoblasts under appropriate condition. The transfected BMSCs are strongly positive for GFP express. Bioluminescence imaging showed that most of BMSCs were trapped in the lung. A small portion BMSCs were homed to the alveolar bone defect area in BMSCs group, while more cells were observed in BMSCs/LIPUS group compare to other groups on day 3 and 7. Micro-CT results showed that BMSCs/LIPUS group resulted in more new bone formation than other groups. Immunohistochemical results showed higher expression of COL-I and osteopontin in BMSCs/LIPUS group compared with the other groups.

CONCLUSIONS

These results suggested that LIPUS can enhance BMSCs-based periodontal alveolar bone regeneration. This study provides new insights into how LIPUS might provide therapeutic benefits by promoting BMSCs homing.

Low-Intensity Pulsed Ultrasound Stimulation for Bone Fractures Healing: A Review

Low-intensity pulsed ultrasound (LIPUS) is a developing technology, which has been proven to improve fracture healing process with minimal thermal effects. This noninvasive treatment accelerates bone formation through various molecular, biological, and biomechanical interactions with tissues and cells. Although LIPUS treatment has shown beneficial effects on different bone fracture locations, only very few studies have examined its effects on deeper bones. This study provides an overview on therapeutic ultrasound for fractured bones, possible mechanisms of action, clinical evidences, current limitations, and its future prospects.

miR-200a-3p represses osteogenesis of human periodontal ligament stem cells by targeting ZEB2 and activating the NF-κB pathway

OBJECTIVES

Human periodontal ligament stem cells (hPDLSCs) bear multilineage differentiation potential and represent the cytological basis of periodontal tissue regeneration. microRNA (miR) is accepted as a critical regulator of cell differentiation. This study explored the molecular mechanism of miR-200a-3p in osteogenesis of hPDLSCs.

MATERIAL AND METHODS

hPDLSCs were cultured and identified in vitro. miR-200a-3p expression during osteogenic differentiation of hPDLSCs was detected. hPDLSCs were transfected with miR-200a-3p mimic or miR-200a-3p inhibitor. Alkaline phosphatase (ALP) activity, calcified nodules and osteogenesis-related genes of hPDLSCs were measured. The binding relationship between miR-200a-3p and ZEB2 was predicted and verified. hPDLSCs were infected with sh-ZEB2, and then the osteogenic capacity was examined. miR-200a-3p inhibitor-transfected hPDLSCs were infected with sh-ZEB2. The key proteins of the NF-κB pathway were measured.

RESULTS

miR-200a-3p expression was downregulated during osteogenic differentiation of hPDLSCs. Upregulation of miR-200a-3p reduced ALP activity, calcified nodules and osteogenesis-related genes of hPDLSCs, while downregulation of miR-200a-3p facilitated the osteogenesis of hPDLSCs. miR-200a-3p targeted ZEB2. ZEB2 silencing repressed osteogenesis of hPDLSCs. ZEB2 silencing attenuated the promoting effect of miR-200a-3p inhibitor on osteogenesis of hPDLSCs. miR-200a-3p activated the NF-κB pathway by targeting ZEB2.

CONCLUSION

miR-200a-3p repressed osteogenesis of hPDLSCs by targeting ZEB2 and activating the NF-κB pathway. This study may offer insights for periodontal tissue regeneration engineering.

LIPUS inhibits inflammation and catabolism through the NF-κB pathway in human degenerative nucleus pulposus cells

Background

Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects. The current study investigated the effect of LIPUS on the inflammation of nucleus pulposus (NP) cells and its underlying mechanism.

Methods

Human NP cells were acquired from lumbar disc herniation tissue samples and cultured for experiments. Human NP cells were treated with LPS and then exposed to LIPUS (15 mW/cm², 30 mW/cm² and 60 mW/cm²) for 20 min daily for 3 days to determine the appropriate intensity to inhibit the expression of the inflammatory factors TNF-α and IL-1β. The gene and protein expression of aggrecan, collagen II, MMP-3 and MMP-9 was measured by real‐time PCR and western blotting, respectively. The activity of the nuclear factor‐kappa B (NF‐κB) pathway was examined by western blotting and immunofluorescence. After pretreatment with the NF-κB inhibitor PDTC, the expression of TNF-α, IL-1β, MMP-3 and MMP-9 was measured by real‐time PCR.

Results

LIPUS at intensities of 15 mW/cm², 30 mW/cm² and 60 mW/cm² inhibited LPS-induced NP cell expression of the inflammatory factors TNF-α and IL-1β, especially at 30 mW/cm². LIPUS significantly upregulated the gene and protein expression of aggrecan and collagen II and downregulated the gene and protein expression of MMP-3 and MMP-9 in LPS-induced NP cells. The NF‐κB signaling pathway was inhibited by LIPUS through inhibiting the protein expression of p-P65 and the translocation of P65 into the nucleus in LPS-induced NP cells. In addition, LIPUS had similar effects as the NF-κB inhibitor PDTC by inhibiting the NF-κB signaling pathway, inflammation and catabolism in LPS-induced human degenerative nucleus pulposus cells.

Conclusion

LIPUS inhibited inflammation and catabolism through the NF‐κB pathway in human degenerative nucleus pulposus cells.

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

Among oral tissues, the periodontium is permanently subjected to mechanical forces resulting from chewing, mastication, or orthodontic appliances. Molecularly, these movements induce a series of subsequent signaling processes, which are embedded in the biological concept of cellular mechanotransduction (MT). Cell and tissue structures, ranging from the extracellular matrix (ECM) to the plasma membrane, the cytosol and the nucleus, are involved in MT. Dysregulation of the diverse, fine-tuned interaction of molecular players responsible for transmitting biophysical environmental information into the cell's inner milieu can lead to and promote serious diseases, such as periodontitis or oral squamous cell carcinoma (OSCC). Therefore, periodontal integrity and regeneration is highly dependent on the proper integration and regulation of mechanobiological signals in the context of cell behavior. Recent experimental findings have increased the understanding of classical cellular mechanosensing mechanisms by both integrating exogenic factors such as bacterial gingipain proteases and newly discovered cell-inherent functions of mechanoresponsive co-transcriptional regulators such as the Yes-associated protein 1 (YAP1) or the nuclear cytoskeleton. Regarding periodontal MT research, this review offers insights into the current trends and open aspects. Concerning oral regenerative medicine or weakening of periodontal tissue diseases, perspectives on future applications of mechanobiological principles are discussed.

Effect of Acoustic Cavitation on Mouse Spermatogonial Stem Cells: Colonization and Viability

OBJECTIVES

The mechanical index has long been one of the main criteria used to assess the safety limits for therapeutic medical applications. However, the safety of the mechanical index parameter is considered to be unknown in male fertility, which has a very significant role in vitro conditions. In this study, the effect of cavitation interactions due to mechanical index regions was evaluated on spermatogonial stem cells.

METHODS

The acoustic pressure and mechanical index equations at the low intensities and the intended frequency were modeled and solved. The mechanical index average of 40 kHz frequency was selected as subthreshold, 0.70, and above the cavitation threshold. Neonatal spermatogonial stem cells were cultured. Spermatogonial stem cells are stimulated by low-level ultrasound for 5 days and colonization and viability evaluated on the seventh day.

RESULTS

Based on modeling, the mechanical index average was chosen as 0.40, 0.51, 0.75, and 0.89. The mechanical index of 0.40 and 0.89 resulted in a number of colonies of 93 ± 4 and 32 ± 4, respectively. An increase in colony diameter could be observed for a 0.40 mechanical index during all days of the culture that in the culture on the seventh day had the largest average colony diameter of 174.05 ± 1.22 μm in comparison with other groups (p < 0.05). The cell viability was not significantly different among the groups.

CONCLUSION

The results suggest that a low-intensity ultrasound of 40 kHz with a 0.40 mechanical index can be effective in increasing the proliferation and colonization of spermatogonia in stem cells during culture.

Low-intensity pulsed ultrasound inhibits IL-6 in subchondral bone of temporomandibular joint osteoarthritis by suppressing the TGF-β1/Smad3 pathway

OBJECTIVE

This study aimed to provide further information on the exact mechanisms involved in the anti-inflammatory effect of low-intensity pulsed ultrasound (LIPUS) on rabbit temporomandibular joint osteoarthritis (TMJOA) on interleukin-6 (IL-6) production in subchondral bone, IL-6 production in IL-1β stimulated via inhibition of the TGF-β1/Smad3 pathway in mouse embryo osteoblast precursor (MC3T3-E1) cells.

DESIGN

Bilateral joints were injected with type II collagenase to establish TMJOA models in two male and four female rabbits. The left joint was continuously stimulated by LIPUS, while the right joint was treated with the power off in this model. One male and two female rabbits were used as normal healthy controls without treatment. The histological features of subchondral bone were examined by Safranin-O/Fast staining. Immunohistochemistry was conducted to evaluate IL-6 expression. Then, cells were stimulated by LIPUS with IL-1β. IL-6 expression and activity of the TGF-β1/Smad3 pathway were evaluated by Enzyme-linked immunosorbent assay (ELISA), Immunofluorescence and Western blotting, respectively. Specific inhibition of the TGF-β1/Smad3 pathway was conducted by transfecting with small interfering RNA (siRNA) of type II receptor (siTβRII).

RESULTS

LIPUS significantly ameliorated the production of IL-6 in vitro and in vivo. Its inhibitory effect on the production of IL-6 induced by IL-1β in MC3T3-E1 cells was partly reversed by siTβRII knockdown.

CONCLUSIONS

LIPUS inhibited IL-6 production by suppressing the TGF-β1/Smad3 pathway of subchondral bone in TMJOA. These data revealed the part of the pathways involved in the anti-inflammatory effect of LIPUS and provided a possible treatment strategy for TMJOA patients and other inflammatory diseases.

Evaluating the Effectiveness of Biophysical Methods of Osteogenesis Stimulation: Review

Background. Stimulation of osteogenesis (SO) by biophysical methods has been widely used in practice to accelerate healing or stimulate the healing of fractures with non-unions, since the middle of the XIX century. SO can be carried out by direct current electrostimulation, or indirectly by low-intensity pulsed ultrasound, capacitive electrical coupling stimulation, and pulsed electromagnetic field stimulation. SO simulates natural physiological processes: in the case of electrical stimulation, it changes the electromagnetic potential of damaged cell tissues in a manner similar to normal healing processes, or in the case of low-intensity pulsed ultrasound, it produces weak mechanical effects on the fracture area. SO increases the expression of factors and signaling pathways responsible for tissue regeneration and bone mineralization and ultimately accelerates bone union.The purpose of this review was to present the most up-to-date data from laboratory and clinical studies of the effectiveness of SO.Material and Methods. The results of laboratory studies and the final results of metaanalyses for each of the four SO methods published from 1959 to 2020 in the PubMed, EMBASE, and eLibrary databases are reviewed.Conclusion. The use of SO effectively stimulates the healing of fractures with the correct location of the sensors, compliance with the intensity and time of exposure, as well as the timing of use for certain types of fractures. In case of non-union or delayed union of fractures, spondylodesis, arthrodesis, preference should be given to non-invasive methods of SO. Invasive direct current stimulation can be useful for non-union of long bones, spondylodesis with the risk of developing pseudoarthrosis.

Evaluating the Effectiveness of Biophysical Methods of Osteogenesis Stimulation: Review

Background. Stimulation of osteogenesis (SO) by biophysical methods has been widely used in practice to accelerate healing or stimulate the healing of fractures with non-unions, since the middle of the XIX century. SO can be carried out by direct current electrostimulation, or indirectly by low-intensity pulsed ultrasound, capacitive electrical coupling stimulation, and pulsed electromagnetic field stimulation. SO simulates natural physiological processes: in the case of electrical stimulation, it changes the electromagnetic potential of damaged cell tissues in a manner similar to normal healing processes, or in the case of low-intensity pulsed ultrasound, it produces weak mechanical effects on the fracture area. SO increases the expression of factors and signaling pathways responsible for tissue regeneration and bone mineralization and ultimately accelerates bone union.The purpose of this review was to present the most up-to-date data from laboratory and clinical studies of the effectiveness of SO.Material and Methods. The results of laboratory studies and the final results of metaanalyses for each of the four SO methods published from 1959 to 2020 in the PubMed, EMBASE, and eLibrary databases are reviewed.Conclusion. The use of SO effectively stimulates the healing of fractures with the correct location of the sensors, compliance with the intensity and time of exposure, as well as the timing of use for certain types of fractures. In case of non-union or delayed union of fractures, spondylodesis, arthrodesis, preference should be given to non-invasive methods of SO. Invasive direct current stimulation can be useful for non-union of long bones, spondylodesis with the risk of developing pseudoarthrosis.

Osteogenesis, angiogenesis and immune response of Mg-Al layered double hydroxide coating on pure Mg

Layered double hydroxides (LDHs) are widely studied to enhance corrosion resistance and biocompatibility of Mg alloys, which are promising bone implants. However, the influence of LDH coating on the osteointegration of Mg implants lacks of a systematic study. In this work, Mg-Al LDH coating was prepared on pure Mg via hydrothermal treatment. The as-prepared Mg-Al LDH coated Mg exhibited better in vitro and in vivo corrosion resistance than bare Mg and Mg(OH)2 coated Mg. In vitro culture of mouse osteoblast cell line (MC3T3-E1) suggested that Mg-Al LDH coated Mg was more favorable for its osteogenic differentiation. In vitro culture of HUVECs revealed that cells cultured in the extract of Mg-Al LDH coated Mg showed superior angiogenic behaviors. More importantly, the immune response of Mg-Al LDH coated Mg was studied by in vitro culturing murine-derived macrophage cell line (RAW264.7). The results verified that Mg-Al LDH coated Mg could induce macrophage polarize to M2 phenotype (anti-inflammatory). Furthermore, the secreted factor in the macrophage-conditioned culture medium of Mg-Al LDH group was more suitable for the bone differentiation of rat bone marrow stem cells (rBMSCs) and the angiogenic behavior of human umbilical vein endothelial cells (HUVECs). Finally, the result of femoral implantation suggested that Mg-Al LDH coated Mg exhibited better osteointegration than bare Mg and Mg(OH)2 coated Mg. With favorable in vitro and in vivo performances, Mg-Al LDH is promising as protective coating on Mg for orthopedic applications.

[Role of growth arrest-specific protein 6 in migration and osteogenic differentiation of human periodontal ligament cells]

OBJECTIVE

To investigate the role of growth arrest-specific protein 6 (Gas6) in the process of the migration and osteogenic differentiation of human periodontal ligament cells (hPDLCs).

METHODS

After different concentrations of recombinant human Gas6 (rhGas6) were added to hPDLCs, cell prolife-ration experiment (CCK-8) was taken to observe the effect of rhGas6 on hPDLCs cell proliferation. Scratch test and cell migration test (Transwell) were taken to analyze the migratory ability of hPDLCs in different concentrations of rhGas6 groups. After osteogenic induction, real-time quantitative polymerase chain reaction (real-time PCR) was taken to detect the expression of the Runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP). ALP staining was used to detect the amount of mineralized nodules.

RESULTS

After adding different concentrations of rhGas6, there were no statistically significant differences in hPDLCs cell proliferation among the experimental groups and the control group at 24, 48 and 72 hours (P>0.05). After 24 h of scratch, the healing area in the 800 μg/L of the rhGas6 group was greater than that in the control group, but without statistically significant difference (31.06%±13.70% vs. 21.79%±9.51%, P>0.05). In the migration test, after 24 h, the number of hPDLCs cells which penetrated through the membrane in the 800 μg/L rhGas6 group was significantly higher than that in the control group (P < 0.01). After rhGas6 was added and osteogenic induction, Runx2 and ALP gene expressions of hPDLCs in the 800 μg/L group were significantly higher than those in the control group (1.60±0.30 vs. 0.91±0.10, 2.81±0.61 vs. 0.86±0.12, P < 0.01). After Gas6 was knocked down, the ALP expression of hPDLCs was significantly lower than that of the control group (0.39±0.07 vs. 0.92±0.14, P < 0.01). There was no significant change in Runx2 expression (P>0.05). After 7 days of osteogenic induction, the mineralized nodules formed in the Gas6 knockdown group were significantly less than those in control group (0.25±0.04 vs. 1.00±0.11, P < 0.001). After 14 days of induction, the staining degree of the Gas6 knockdown group was lower than that of the control group, but there was no significant difference (0.86±0.04 vs. 1.00±0.16, P>0.05).

CONCLUSION

After downregulation of Gas6 gene, mineralized nodule formation was reduced and ALP gene expressions were decreased in the early stage of osteogenic induction (7 days). After addition of rhGas6, Runx2 and ALP gene expressions were increased and the number of cell migration was increased, suggesting that Gas6 might play a promoting role in the migration and osteogenic differentiation of human periodontal ligament cells.

Low-intensity pulsed ultrasound activates autophagy in periodontal ligament cells in the presence or absence of lipopolysaccharide

OBJECTIVE

This study aims to determine if low-intensity pulsed ultrasound (LIPUS) activates autophagy in human periodontal ligament cells (PDLCs) irrespective of lipopolysaccharide.

DESIGN

Six groups were designed: control, LIPUS, lipopolysaccharide, LIPUS + lipopolysaccharide, LIPUS+3-Methyladenine, LIPUS + lipopolysaccharide+3-Methyl- adenine. LIPUS pretreated PDLCs for 2 h and lipopolysaccharide treated for different times. Real-time PCR and Western-blot were performed to evaluate mRNA and protein expression levels of autophagic genes Beclin-1 and LC3 respectively. A transmission electronic microscope was used to observe the autophagosome. ELISA was used to test interleukin-6 expression.

RESULTS

Compared with the non-treatment, LIPUS pretreatment increased mRNA expression levels of LC3 (P < 0.05) and Beclin-1 (P < 0.05) at 4 h and 8 h, and enhanced the protein expression levels of LC3-Ⅱ at 8 h (P<0.05) and Beclin-1 at 4 h, 8 h and 16 h(P<0.05). After LIPUS pretreatment and lipopolysaccharide treatment for 8 h, LC3-Ⅱ and Beclin-1 protein expression levels were elevated (P < 0.05) compared with the control. Following further treatment by 3-Methyladenine, Beclin-1 protein expression was decreased (P < 0.05) compared with the LIPUS plus lipopolysaccharide group, but LC3-Ⅱ protein expression was not. Autophagosomes were not found in the LIPUS+3-Methyladenine and LIPUS+lipopolysaccharide+3-Methyladenine groups. After LIPUS pretreatment and lipopolysaccharide treatment for 36 h, intreleukin-6 expression was decreased (P<0.05) compared with the lipopolysaccharide group. However, after addition of 3-Methyladenine, intreleukin-6 expression was elevated (P < 0.05) compared with the LIPUS +lipopolysaccharide group.

CONCLUSIONS

LIPUS can promote autophagy in PDLCs irrespective of lipopolysaccharide. Autophagy might be involved in LIPUS anti-inflammatory mechanism in PDLCS.

Low-Intensity Ultrasound Modulation May Prevent Myocardial Infarction-induced Sympathetic Neural Activation and Ventricular Arrhythmia

BACKGROUND

Low-intensity focused ultrasound (LIFU) has been shown to be a beneficial tool for autonomic nervous system modulation, but its effect on the left stellate ganglion (LSG) remains unknown.

OBJECTIVE

To seek the effect of LIFU on myocardial infarction (MI)-induced LSG activation and ventricular arrhythmias (VAs).

METHODS

In this study, 20 dogs were included and randomly divided into the LIFU (LIFU & MI, n = 8), Sham (sham LIFU & MI, n = 8), and Control group (sham LIFU & sham MI, n = 4). For each LIFU intervention (1.0-2.0 W, 10 minutes) of the LSG, the LSG function, ventricular effective refractory period (ERP), and temperature were tested pre-intervention and postintervention. Thereafter, MI was induced by left anterior artery ligation and VAs were recorded for 1 hour. At the end, both the LSG and the heart were extracted for biomedical and histological analysis.

RESULTS

In the Sham group, no significant change was shown in ventricular ERP or LSG function for any intensity settings of sham LIFU intervention when compared with the group baseline. In the LIFU group, however, both 1.5 and 2.0 W LIFU modulation of LSG resulted in significant prolongation of ERP and attenuation of LSG function. Furthermore, the incidence of VAs was significantly attenuated in the LIFU group compared with the Sham group. Moreover, histological analysis showed that no damage or apoptosis was observed in LSG although a statistically significant increase was shown in temperature (maximal increase <1°C) with 1.5 and 2.0 W LIFU intervention.

CONCLUSION

LIFU stimulation may be a safe and beneficial tool for LSG attenuation and VA prevention in the MI canine model.