LIPUS regulates the progression of knee osteoarthritis in mice through primary cilia-mediated TRPV4 channels

Osteoarthritis (OA) is a common disease in middle-aged and elderly people. An imbalance in calcium ion homeostasis will contribute to chondrocyte apoptosis and ultimately lead to the progression of OA. Transient receptor potential channel 4 (TRPV4) is involved in the regulation of intracellular calcium homeostasis. TRPV4 is expressed in primary cilia, which can sense mechanical stimuli from outside the cell, and its abnormal expression is closely related to the development of OA. Low-intensity pulsed ultrasound (LIPUS) can alleviate chondrocyte apoptosis while the exact mechanism is unclear. In this project, with the aim of revealing the mechanism of action of LIPUS, we proposed to use OA chondrocytes and animal models, LIPUS intervention, inhibition of primary cilia, use TRPV4 inhibitors or TRPV4 agonist, and use Immunofluorescence (IF), Immunohistochemistry (IHC), Western Blot (WB), Quantitative Real-time PCR (QP) to detect the expression of cartilage synthetic matrix and endoplasmic reticulum stress markers. The results revealed that LIPUS altered primary cilia expression, promoted synthetic matrix metabolism in articular chondrocytes and was associated with primary cilia. In addition, LIPUS exerted a active effect on OA by activating TRPV4, inducing calcium inward flow, and facilitating the entry of NF-κB into the nucleus to regulate synthetic matrix gene transcription. Inhibition of TRPV4 altered primary cilia expression in response to LIPUS stimulation, and knockdown of primary cilia similarly inhibited TRPV4 function. These results suggest that LIPUS mediates TRPV4 channels through primary cilia to regulate the process of knee osteoarthritis in mice.

Low-intensity pulsed ultrasound (LIPUS) promotes skeletal muscle regeneration by regulating PGC-1α/AMPK/GLUT4 pathways in satellite cells/myoblasts

Low-Intensity Pulsed Ultrasound (LIPUS) holds therapeutic potential in promoting skeletal muscle regeneration, a biological process mediated by satellite cells and myoblasts. Despite their central roles in regeneration, the detailed mechanistic of LIPUS influence on satellite cells and myoblasts are not fully underexplored. In the current investigation, we administrated LIPUS treatment to injured skeletal muscles and C2C12 myoblasts over five consecutive days. Muscle samples were collected on days 6 and 30 post-injury for an in-depth histological and molecular assessment, both in vivo and in vitro with immunofluorescence analysis. During the acute injury phase, LIPUS treatment significantly augmented the satellite cell population, concurrently enhancing the number and size of newly formed myofibers whilst reducing fibrosis levels. At 30 days post-injury, the LIPUS-treated group demonstrated a more robust satellite cell pool and a higher myofiber count, suggesting that early LIPUS intervention facilitates satellite cell proliferation and differentiation, thereby promoting long-term recovery. Additionally, LIPUS markedly accelerated C2C12 myoblast differentiation, with observed increases in AMPK phosphorylation in myoblasts, leading to elevated expression of Glut4 and PGC-1α, and subsequent glucose uptake and mitochondrial biogenesis. These findings imply that LIPUS-induced modulation of myoblasts may culminate in enhanced cellular energy availability, laying a theoretical groundwork for employing LIPUS in ameliorating skeletal muscle regeneration post-injury. NEW & NOTEWORTHY: Utilizing the cardiotoxin (CTX) muscle injury model, we investigated the influence of LIPUS on satellite cell homeostasis and skeletal muscle regeneration. Our findings indicate that LIPUS promotes satellite cell proliferation and differentiation, thereby facilitating skeletal muscle repair. Additionally, in vitro investigations lend credence to the hypothesis that the regulatory effect of LIPUS on satellite cells may be attributed to its capability to enhance cellular energy metabolism.

The value of low-intensity pulsed ultrasound in reducing ovarian injury caused by chemotherapy in mice

BACKGROUND

Ovarian damage and follicle loss are major side effects of chemotherapy in young female patients with cancer. However, effective strategies to prevent these injuries are still lacking. The purpose of this study was to verify low-intensity pulsed ultrasound (LIPUS) can reduce ovarian injury caused by chemotherapy and to explore its underlying mechanisms in mice model.

METHODS

The mice were randomly divided into the Control group, Cisplatin group, and Cisplatin + LIPUS group. The Cisplatin group and Cisplatin + LIPUS group were intraperitoneally injected with cisplatin every other day for a total of 10 injections, and the Control group was injected with saline. On the second day of each injection, the Cisplatin + LIPUS group received irradiation, whereas the other two groups received sham irradiation. We used a variety of biotechnologies to detect the differences in follicle count, granulosa cell apoptosis, fibrosis, transcriptome level, oxidative damage, and inflammation in differently treated mice.

RESULT

LIPUS was able to reduce primordial follicle pool depletion induced by cisplatin and inhibit the apoptosis of granulosa cells. Transcriptomic results confirmed that LIPUS can reduce ovarian tissue injury. We demonstrated that LIPUS can relieve ovarian fibrosis by inhibiting TGF-β1/Smads pathway. Meanwhile, it can reduce the oxidative damage and reduced the mRNA levels of proinflammatory cytokines caused by chemotherapy.

CONCLUSION

LIPUS can reduce the toxic effects of chemotherapy drugs on ovaries, inhibit ovarian fibrosis, reduce the inflammatory response, and redcue the oxidative damage, reduce follicle depletion and to maintain the number of follicle pools.

Efficacy of Wearable low-intensity pulsed Ultrasound treatment in the Movement disorder in Parkinson's disease (the SWUMP trial): protocol for a single-site, double-blind, randomized controlled trial

BACKGROUND

Parkinson's disease (PD) is a progressive, neurodegenerative illness marked by the loss of dopaminergic neurons, causing motor symptoms. Oral levodopa replacement therapy remains the gold standard in the treatment of PD. It is, nevertheless, a symptomatic treatment. There is currently no effective treatment for PD. Therefore, new therapies for PD are highly desirable. Low-intensity pulsed ultrasound (LIPUS) has been shown to improve behavioral functions in PD animal models. It is a new type of neuromodulation approach that combines noninvasiveness with high spatial precision. The purpose of this study is to establish a new clinical protocol for LIPUS in the treatment of movement disorders in patients with PD.

METHODS

This protocol is a single-site, prospective, double-blind, randomized controlled trial (RCT). Forty-eight participants with clinically confirmed PD will be randomly allocated to one of two groups: LIPUS group or sham group. All of the participants continue to use pharmacological therapy as a fundamental treatment. The primary outcome is the difference between groups from baseline to 4 months in the change in the Unified Parkinson's Disease Rating Scale (UPDRS) motor score (part III). The secondary outcomes include the rating scales such as the Mini-Mental State Examination (MMSE), and other three rating scales, and medical examinations including high-density electroencephalography (hdEEG) and functional magnetic resonance imaging (fMRI). The primary safety outcome will be assessed at 4 months, and adverse events will be recorded.

DISCUSSION

This study represents the clinical investigation into the efficacy of therapeutic LIPUS in the treatment of PD for the first time. If LIPUS is determined to be effective, it could offer a practical and innovative means of expanding the accessibility of ultrasound therapy by using a wearable LIPUS device within a home setting.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100052093. Registered on 17 October 2021.

Low-Intensity Pulsed Ultrasound Protects SH-SY5Y Cells Against 6-Hydroxydopamine-Induced Neurotoxicity by Upregulating Neurotrophic Factors

OBJECTIVE

Neonatal hypoxic-ischemic brain damage (HIBD) can have long-term implications on patients' physical and mental health, yet the available treatment options are limited. Recent research has shown that low-intensity pulsed ultrasound (LIPUS) holds promise for treating neurodegenerative diseases and traumatic brain injuries. Our objective was to explore the therapeutic potential of LIPUS for HIBD.

METHODS

Due to the lack of a suitable animal model for neonatal HIBD, we will initially simulate the therapeutic effects of LIPUS on neuronal cells under oxidative stress and neuroinflammation using cell experiments. Previous studies have investigated the biologic responses following intracranial injection of 6-hydroxydopamine (6-OHDA). In this experiment, we will focus on the biologic effects produced by LIPUS treatment on neuronal cells (specifically, SH-SY5Y cells) without the presence of other neuroglial cell assistance after stimulation with 6-OHDA.

RESULTS

We found that (i) pulsed ultrasound exposure, specifically three-intermittent sonication at intensities ranging from 0.1 to 0.5 W/cm², did not lead to a significant decrease in viability among SH-SY5Y cells; (ii) LIPUS treatment exhibited a positive effect on cell viability, accompanied by an increase in glial cell-derived neurotrophic factor (GDNF) levels and a decrease in caspase three levels; (iii) the administration of 6-OHDA had a significant impact on cell viability, resulting in a decrease in both brain cell-derived neurotrophic factor (BDNF) and GDNF levels, while concurrently elevating caspase three and matrix metalloproteinase-9 (MMP-9) levels; and (iv) LIPUS treatment demonstrated its potential to alleviate the changes induced by 6-OHDA, particularly in the levels of BDNF, GDNF, and tyrosine hydroxylase (TH).

CONCLUSION

LIPUS treatment may possess partial therapeutic capabilities for SH-SY5Y cells damaged by 6-OHDA neurotoxicity. Our findings enhance our understanding of the effects of LIPUS treatment on cell viability and its modulation of key factors involved in the pathophysiology of HIBD and show the promising potential of LIPUS as an alternative therapeutic approach for neonates with HIBD.

Low-intensity pulsed ultrasound reduces alveolar bone resorption during orthodontic treatment via Lamin A/C-Yes-associated protein axis in stem cells

BACKGROUND

The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years, which also may lead to some complications such as alveolar bone resorption or tooth root resorption. Low-intensity pulsed ultrasound (LIPUS), a noninvasive physical therapy, has been shown to promote bone fracture healing. It is also reported that LIPUS could reduce the duration of orthodontic treatment; however, how LIPUS regulates the bone metabolism during the orthodontic treatment process is still unclear.

AIM

To investigate the effects of LIPUS on bone remodeling in an orthodontic tooth movement (OTM) model and explore the underlying mechanisms.

METHODS

A rat model of OTM was established, and alveolar bone remodeling and tooth movement rate were evaluated via micro-computed tomography and staining of tissue sections. In vitro, human bone marrow mesenchymal stem cells (hBMSCs) were isolated to detect their osteogenic differentiation potential under compression and LIPUS stimulation by quantitative reverse transcription-polymerase chain reaction, Western blot, alkaline phosphatase (ALP) staining, and Alizarin red staining. The expression of Yes-associated protein (YAP1), the actin cytoskeleton, and the Lamin A/C nucleoskeleton were detected with or without YAP1 small interfering RNA (siRNA) application via immunofluorescence.

RESULTS

The force treatment inhibited the osteogenic differentiation potential of hBMSCs; moreover, the expression of osteogenesis markers, such as type 1 collagen (COL1), runt-related transcription factor 2, ALP, and osteocalcin (OCN), decreased. LIPUS could rescue the osteogenic differentiation of hBMSCs with increased expression of osteogenic marker inhibited by force. Mechanically, the expression of LaminA/C, F-actin, and YAP1 was downregulated after force treatment, which could be rescued by LIPUS. Moreover, the osteogenic differentiation of hBMSCs increased by LIPUS could be attenuated by YAP siRNA treatment. Consistently, LIPUS increased alveolar bone density and decreased vertical bone absorption in vivo. The decreased expression of COL1, OCN, and YAP1 on the compression side of the alveolar bone was partially rescued by LIPUS.

CONCLUSION

LIPUS can accelerate tooth movement and reduce alveolar bone resorption by modulating the cytoskeleton-Lamin A/C-YAP axis, which may be a promising strategy to reduce the orthodontic treatment process.

Photobiomodulation and low-intensity pulsed ultrasound synergistically enhance dental mesenchymal stem cells viability, migration and differentiation: an invitro study

Novel methods and technologies that improve mesenchymal stem cells (MSCs) proliferation and differentiation properties are required to increase their clinical efficacy. Photobiomodulation (PBM) and low-intensity pulsed ultrasound (LIPUS) are two strategies that can be used to enhance the regenerative properties of dental MSCs. This study evaluated the cytocompatibility and osteo/odontogenic differentiation of dental pulp, periodontal ligament, and gingival MSCs after stimulation by either PBM or LIPUS and their combined effect. MTT assay, cell migration assay, osteo/odontogenic differentiation by AR staining and ALP activity, and expression of osteo/odontogenic markers (OPG, OC, RUNX2, DSPP, DMP1) by RT-qPCR were evaluated. Statistical analysis was performed using ANOVA, followed by Tukey's post hoc test, with a p-value of less than 0.05 considered significant. The results showed that combined stimulation by PBM and LIPUS resulted in significantly the highest viability of MSCs, the fastest migration, the most dense AR staining, the most increased ALP activity, and the most elevated levels of osteogenic and odontogenic markers. The synergetic stimulation of PBM and LIPUS can be utilized in cell-based regenerative approaches to promote the properties of dental MSCs.

L-Type Calcium Channel Modulates Low-Intensity Pulsed Ultrasound-Induced Excitation in Cultured Hippocampal Neurons

As a noninvasive technique, ultrasound stimulation is known to modulate neuronal activity both in vitro and in vivo. The latest explanation of this phenomenon is that the acoustic wave can activate the ion channels and further impact the electrophysiological properties of targeted neurons. However, the underlying mechanism of low-intensity pulsed ultrasound (LIPUS)-induced neuro-modulation effects is still unclear. Here, we characterize the excitatory effects of LIPUS on spontaneous activity and the intracellular Ca2+ homeostasis in cultured hippocampal neurons. By whole-cell patch clamp recording, we found that 15 min of 1-MHz LIPUS boosts the frequency of both spontaneous action potentials and spontaneous excitatory synaptic currents (sEPSCs) and also increases the amplitude of sEPSCs in hippocampal neurons. This phenomenon lasts for > 10 min after LIPUS exposure. Together with Ca2+ imaging, we clarified that LIPUS increases the [Ca2+]cyto level by facilitating L-type Ca2+ channels (LTCCs). In addition, due to the [Ca2+]cyto elevation by LIPUS exposure, the Ca2+-dependent CaMKII-CREB pathway can be activated within 30 min to further regulate the gene transcription and protein expression. Our work suggests that LIPUS regulates neuronal activity in a Ca2+-dependent manner via LTCCs. This may also explain the multi-activation effects of LIPUS beyond neurons. LIPUS stimulation potentiates spontaneous neuronal activity by increasing Ca2+ influx.

Combined Assessment of 2-D Ultrasound and Real-Time Shear Wave Elastography of Low-Intensity Pulsed Ultrasound Therapy Efficacy in Rabbits with Achilles Tendinopathy

OBJECTIVE

Low-intensity pulsed ultrasound (LIPUS) has been gradually used to treat Achilles tendinopathy. However, there are limited non-invasive and efficient instruments for monitoring LIPUS efficacy in Achilles tendinopathy. The purpose of this study was to assess the therapeutic effectiveness of LIPUS after Achilles tendinopathy by 2-D ultrasound and real-time shear wave elastography (SWE).

METHODS

Ninety New Zealand white rabbits were divided into control, sham and LIPUS groups after tendinopathy modeling. On days 1, 4, 7, 14 and 28, the Achilles tendon thickness and SWE Young's modulus on the long axis were measured. The tissues of the Achilles tendon were then evaluated histologically.

RESULTS

The mean SWE values increased while the average thickness and histologic scores decreased, especially in the LIPUS group (9.5% and 80.7% on day 28, respectively). The SWE values in the LIPUS group were significantly lower than those in the control group on day 1 (121.0 kPa vs. 177.6 kPa) and peaked on day 7 (173.7 kPa, p < 0.001). By day 28, the SWE value had approached that of the control (191.2 kPa vs. 192.4 kPa), and had been significantly higher than that in the sham group since day 7. SWE values and histologic scores were correlated (r = -0.792, p < 0.01). The average thickness decreased in the three groups but did not differ significantly.

CONCLUSION

Two-dimensional ultrasound is beneficial to the diagnosis of Achilles tendinopathy. SWE could quantify changes in Achilles tendon stiffness non-invasively during LIPUS treatment, enabling the study of early Achilles tendon healing after LIPUS treatment.

The impact of ischemic vascular stenosis on LIPU hyperthermia efficacy investigated Based on in vivo rabbit limb ischemia model

Ischemic diseases due to arterial stenosis or occlusion are common and can have serious consequences if untreated. Therapeutic ultrasound like high-intensity focused ultrasound (HIFU) ablates tissues while low-intensity pulsed ultrasound (LIPU) promotes healing at relatively low temperatures. However, blood vessel cooling effect and reduced flow in ischemia impact temperature distribution and ultrasonic treatment efficacy. This work established a rabbit limb ischemia model by ligating the femoral artery, measuring vascular changes and temperature rise during LIPU exposures. Results showed the artery diameter was narrowed by 46.2% and the downstream velocity was reduced by 51.3% after ligation. Finite element simulations verified that the reduced flow velocity impaired heat dissipation, enhancing LIPU-induced heating. Simulation results also suggested the temperature rise was almost related linearly to vessel diameter but decayed exponentially with the increasing flow velocity. Findings indicate that the proposed model could be used as an effectively tool to model the heating effects in ischemic tissues during LIPU treatment. This research on relating varied ischemic flow to LIPU-induced thermal effects is significant for developing safe and efficacious clinical ultrasound hyperthermia treatment protocols for the patients with ischemic diseases.

Low-intensity pulsed ultrasound activated the anti-tumor immunity by irradiating the spleen of mice in 4 T-1 breast cancer

Tumor immunotherapy is booming around the world. However, strategies to activate the immune system and alleviate the immunosuppression still need to be refined. Here, we demonstrate for the first time that low-intensity pulsed ultrasound (LIPUS, spatial average time average intensity (Isata) is 200 mW/cm2, frequency is 0.3 MHz, repetition frequency is 1 kHz, and duty cycle is 20%) triggers the immune system and further reverses the immunosuppressive state in the mouse models of breast cancer by irradiating the spleen of mice. LIPUS inhibited tumor growth and extended survival in mice with 4 T-1 tumors. Further studies had previously shown that LIPUS enhanced the activation of CD4+ and CD8+ T cells in the spleen and led to significant changes in cytokines, as well as induced upregulation of mRNA levels involved in multiple immune regulatory pathways in the spleen. In addition, LIPUS promoted tumor-infiltrating lymphocyte accumulation and CD8+ T cell activation and improved the dynamics of cytokines/chemokines in the tumor microenvironment, resulting in a reversal of the immunosuppressive state of the tumor microenvironment. These results suggest a novel approach to activate the immune response by irradiating the spleen with LIPUS.

The effectiveness of low-level laser therapy and low-intensity pulsed ultrasound in reducing pain induced by orthodontic separation: a randomized controlled trial

BACKGROUND

The low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) have been recently applied to control pain during orthodontic treatment.

OBJECTIVE

To evaluate and compare the effectiveness of LLLT and LIPUS in reducing pain induced by orthodontic separation.

STUDY DESIGN

A single-blinded randomized controlled trial.

METHODS

One hundred and fifty patients were randomly assigned into three groups; LLLT group, LIPUS group, and control group. After 5 min from the separators' placement, the first dose of the laser or the ultrasound was applied, the second dose was applied after 24 h, and the third dose was applied after 48 h on both maxillary and mandibular first molars. The exposure of laser was for 20 s at each point (maxillary and mandibular first molars), with an 810-nm aluminum-gallium-arsenide (AlGaAs) diode laser on continuous mode. The output power set at 150 mW, the energy density of 4 J/cm2, and a laser spot diameter of 7 mm were applied. Whereas the frequency of ultrasonic toothbrush was 1.6 MHz; and average output intensity was 0.2 W/cm2. The application was for 20 min (5 min on each first molar). The control group received the separators without another intervention. A Visual Analog Scale (VAS 100 mm) was used to assess pain intensity at several time intervals during the first four days after the separators' placement.

RESULTS

A total of 145 patients were assessed. There was a significant difference in pain perception among the three groups after 5 min (P = .002). The maximum pain level was reached after 24 h. However, the laser group and the ultrasound group showed a statistically significant decrease in pain scores compared to the control group at all the assessment time points (P < .001). Whereas there was no difference between the laser group and the ultrasound group in reducing the pain scores (P > .05).

CONCLUSIONS

The LLLT and the LIPUS effectively reduce the separation pain when applied in multiple doses without differences between them.

TRIAL REGISTRATION

This trial was registered with the German Clinical Trials Register (DRKS). ( https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID= DRKS00029991). Date of registration: 26/08/2022.

Low-intensity pulsed ultrasound in the treatment of masticatory myositis and temporomandibular joint synovitis: A clinical trial

BACKGROUND

Low-intensity pulsed ultrasound (LIPUS) is a non-invasive physical stimulation application for the therapy of articular cartilage injury. This study aimed to explore the therapeutic effects of low-intensity pulsed ultrasound in treating masticatory myositis and synovitis in temporomandibular joint disorders and to establish an evaluation system to evaluate the clinical efficacy.

METHODS

TMD patients who met the inclusion criteria in the temporomandibular joint clinic of the affiliated Stomatological Hospital of Chongqing Medical University from April 3, 2021, to December 2021 were selected. Before the start and after 7 days of LIPUS treatment, the Fricton temporomandibular joint disorder index, Visual Analog Scale (VAS), and Pressure Difference of Precision Manometer (PD) were measured. A paired t-test was used to compare the values of the Fricton index, VAS, and PD before and after treatment in each group. One-way ANOVA analysis of variance was used to compare the differences between groups.

RESULTS

After one week of LIPUS treatment, the PI, DI and CMI of the Fricton index in the masticatory myositis (PI: P < 0.001; CMI: P < 0.001; DI: P = 0.2641, ns) and the synovitis group (DI: P < 0.001; CMI: P < 0.001, PI: P = 0.9729, ns) significantly decreased. The VAS of the masticatory myositis group and the synovitis group were significantly reduced (P < 0.001). The PD between the affected and healthy sides of the masticatory myositis group and the synovitis group was significantly reduced (P < 0.001), and the reduction was more evident in the M group.

CONCLUSIONS

LIPUS is effective in pain relief in patients with masticatory myositis and joint synovitis, meanwhile, masticatory myositis was more sensitive to LIPUS. A new comprehensive clinical efficacy evaluation system which includes PV, FI, and VAS was created to better 2 diagnose masticatory myositis and joint synovitis.

Protective effect of low-intensity pulsed ultrasound on immune checkpoint inhibitor-related myocarditis via fine-tuning CD4+ T-cell differentiation

PURPOSE

Immune checkpoint inhibitors (ICIs) have transformed traditional cancer treatments. Specifically, ICI-related myocarditis is an immune-related adverse event (irAE) with high mortality. ICIs activate CD4+ T-lymphocyte reprogramming, causing an imbalance between Th17 and Treg cell differentiation, ultimately leading to myocardial inflammatory damage. Low-intensity pulsed ultrasound (LIPUS) can limit inflammatory responses, with positive therapeutic effects across various cardiovascular inflammatory diseases; however, its role in the pathogenesis of ICI-related myocarditis and CD4+ T-cell dysfunction remains unclear. Accordingly, this study investigated whether LIPUS can alleviate ICI-related myocarditis inflammatory damage and, if so, aimed to elucidate the beneficial effects of LIPUS and its underlying molecular mechanisms.

METHODS

An in vivo model of ICI-related myocarditis was obtained by intraperitonially injecting male A/J mice with an InVivoPlus anti-mouse PD-1 inhibitor. LIPUS treatment was performed via an ultrasound-guided application to the heart via the chest wall. The echocardiographic parameters were observed and cardiac function was assessed using an in vivo imaging system. The expression of core components of the HIPPO pathway was analyzed via western blotting.

RESULTS

LIPUS treatment reduced cardiac immune responses and inflammatory cardiac injury. Further, LIPUS treatment alleviated the inflammatory response in mice with ICI-related myocarditis. Mechanistically, in the HIPPO pathway, the activation of Mst1-TAZ axis improved autoimmune inflammation by altering the interaction between the transcription factors FOXP3 and RORγt and regulating the differentiation of Treg and Th17 cells.

CONCLUSION

LIPUS therapy was shown to reduce ICI-related myocarditis inflammatory damage and improve cardiac function, representing an exciting finding for irAEs treatment.

Low-intensity pulsed ultrasound phonophoresis with diclofenac alleviated inflammation and pain via downregulation of M1 macrophages in rats with carrageenan-induced knee joint arthritis

Objective

This study aimed to investigate the effects of low-intensity pulsed ultrasound (LIPUS) phonophoresis with diclofenac on inflammation and pain in the acute phase of carrageenan-induced arthritis in rats.

Design

60 male Wistar rats were randomly divided into the arthritis, diclofenac, LIPUS, phonophoresis, and sham-arthritis control groups. LIPUS and transdermal diclofenac gel were applied to the lateral side of the inflamed knee for 7 days, initiated postinjection day 1. In the phonophoresis group, diclofenac gel was rubbed onto the skin, followed by LIPUS application over the medication. Knee joint transverse diameters, pressure pain thresholds (PPTs), and paw withdrawal thresholds (PWT) were evaluated. The number of CD68-, CD11c-, and CD206-positive cells, and IL-1β and COX-2 mRNA expression were analyzed 8 days after injection.

Results

In the phonophoresis group, the transverse diameter, PPT, PWT significantly recovered at the day 8 compared to those in the LIPUS and diclofenac groups. The number of CD68- and CD11c-positive cells in the phonophoresis group was significantly lower than that in the LIPUS and diclofenac groups, but no significant differences were observed among three groups in CD206-positive cells. IL-1β and COX-2 mRNA levels were lower in the phonophoresis group than in the arthritis group, although there were no differences among the LIPUS, diclofenac, and phonophoresis groups.

Conclusion

LIPUS phonophoresis with diclofenac is more effective to ameliorate inflammation and pain compared to diclofenac or LIPUS alone, and the mechanism involves the decrease of M1 macrophages.

Daily low-intensity pulsed ultrasound stimulation mitigates joint degradation and pain in a post-traumatic osteoarthritis rat model

Objectives

The aim of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) in a post-traumatic osteoarthritis (OA) rat model and in vitro.

Methods

Thirty-eight male, four-month-old Sprague Dawley rats were randomly assigned to Sham, Sham ​+ ​US, OA, and OA ​+ ​US. Sham surgery was performed to serve as a negative control, and anterior cruciate ligament transection was used to induce OA. Three days after the surgical procedures, Sham ​+ ​US and OA ​+ ​US animals received daily LIPUS treatment, while the rest of the groups received sham ultrasound (US) signals. Behavioral pain tests were performed at baseline and every week thereafter. After 31 days, the tissues were collected, and histological analyses were performed on knees and innervated dorsal root ganglia (DRG) neurons traced by retrograde labeling. Furthermore, to assess the activation of osteoclasts by LIPUS treatment, RAW264.7 ​cells were differentiated into osteoclasts and treated with LIPUS.

Results

Joint degradation in cartilage and bone microarchitecture were mitigated in OA ​+ ​US compared to OA. OA ​+ ​US showed improvements in behavioral pain tests. A significant increase of large soma-sized DRG neurons was located in OA compared to Sham. In addition, a greater percentage of large soma-sized innervated neurons were calcitonin gene-related peptide-positive. Daily LIPUS treatment suppressed osteoclastogenesis in vitro, which was confirmed via histological analyses and mRNA expression. Finally, lower expression of netrin-1, a sensory innervation-related protein, was found in the LIPUS treated cells.

Conclusion

Our findings demonstrate that early intervention using LIPUS treatment has protective effects from the progression of knee OA, including reduced tissue degradation, mitigated pain characteristics, improved subchondral bone microarchitecture, and less sensory innervation. Furthermore, daily LIPUS treatment has a suppressive effect on osteoclastogenesis, which may be linked to the suppression of sensory innervation in OA.

The translational potential of this article

This study presents a new potential for early intervention in treating OA symptoms through the use of LIPUS, which involves the suppression of osteoclastogenesis and the alteration of DRG profiles. This intervention aims to delay joint degradation and reduce pain.

LIPUS Alleviates Knee Joint Capsule Fibrosis in Rabbits by Regulating SOD/ROS Dynamics and Inhibiting the TGF-β1/Smad Signaling Pathway

OBJECTIVE

The aim of the work described here was to investigate the efficacy and potential mechanisms of low-intensity pulsed ultrasound (LIPUS) for the treatment of arthrogenic contracture induced by immobilization in rabbits.

METHODS

The left knee joint of rabbits was immobilized for 6 wk to establish the model of extending knee joint contracture. The rabbits were divided into a control group (C), a group immobilized for 6 wk (IM-6w), a group remobilized for 1 wk (RM-1w), a group subjected to LIPUS intervention for 1 wk (LIPUS-1w), a group remobilized for 2 wk (RM-2w) and a group subjected to LIPUS intervention for 2 wk (LIPUS-2w). The degrees of arthrogenic contracture and joint capsule fibrosis were assessed, as were the levels of reactive oxygen species (ROS) and the activation status of the TGF-β1/Smad signaling pathway in the joint capsule.

RESULTS

After immobilization for 6 wk, the degrees of arthrogenic contracture and joint capsule fibrosis increased. The ROS level increased, as evidenced by an increase in malondialdehyde content and a decrease in superoxide dismutase content. In addition, the TGF-β1/Smad signaling pathway was significantly activated. The degrees of knee joint contracture increased in the first week after remobilization and decreased in the second week. Furthermore, joint capsule fibrosis continued to develop during the 2 wk of remobilization, and the ROS level increased, while the TGF-β1/Smad signaling pathway was significantly activated. LIPUS effectively reduced the level of ROS in the joint capsule, which further inhibited activation of the TGF-β1/Smad signaling pathway, thereby improving joint capsule fibrosis and reducing arthrogenic contracture.

CONCLUSION

The high ROS levels and overactivation of the TGF-β1/Smad signaling pathway may be reasons why immobilization induces knee joint capsule fibrosis. LIPUS can alleviate the degree of knee joint capsule fibrosis induced by immobilization by inhibiting the production of ROS and the activation of the TGF-β1/Smad signaling pathway.

Therapeutic ultrasound treatment for the prevention of chronic kidney disease-associated muscle wasting in mice

Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound. It can help improve bone fracture repair and soft tissue healing. Our previous study found that LIPUS treatment could halt the chronic kidney disease (CKD) progression in mice; unexpectedly, we observed the improvement of CKD-reduced muscle weights by LIPUS treatment. Here, we further tested the protective potential of LIPUS on CKD-associated muscle wasting/sarcopenia using the CKD mouse models. Mouse models of both unilateral renal ischemia/reperfusion injury (IRI) with nephrectomy and adenine administration were used to induce CKD. LIPUS with condition of 3 MHz, 100 mW/cm², 20 min/day was applied to the kidney of CKD mice. LIPUS treatment significantly reversed the increased serum BUN/creatinine levels in CKD mice. LIPUS effectively prevented the decrease in grip strength, muscle weight (soleus, tibialis anterior, and gastrocnemius muscles), cross-section areas of muscle fibres, and muscular phosphorylated Akt protein expression by immunohistochemistry, and the increase in muscular atrogenes Atrogin1 and MuRF1 protein expression by immunohistochemistry in CKD mice. These results indicated that LIPUS could help improve weak muscle strength, muscle mass loss, muscle atrophy-related protein expression, and Akt inactivation. LIPUS application may be an alternative non-invasive therapeutic intervention on the management of CKD-associated muscle wasting.

Low-Intensity Pulsed Ultrasound Promotes BMP9 Induced Osteoblastic Differentiation in Rat Dedifferentiated Fat Cells

Dedifferentiated fat cells (DFATs) isolated from mature adipocytes have a multilineage differentiation capacity similar to mesenchymal stem cells and are considered as promising source of cells for tissue engineering. Bone morphogenetic protein 9 (BMP9) and low-intensity pulsed ultrasound (LIPUS) have been reported to stimulate bone formation both in vitro and in vivo. However, the combined effect of BMP9 and LIPUS on osteoblastic differentiation of DFATs has not been studied. After preparing DFATs from mature adipose tissue from rats, DFATs were treated with different doses of BMP9 and/or LIPUS. The effects on osteoblastic differentiation were assessed by changes in alkaline phosphatase (ALP) activity, mineralization/calcium deposition, and expression of bone related genes; Runx2, osterix, osteopontin. No significant differences for ALP activity, mineralization deposition, as well as expression for bone related genes were observed by LIPUS treatment alone while treatment with BMP9 induced osteoblastic differentiation of DFATs in a dose dependent manner. Further, co-treatment with BMP9 and LIPUS significantly increased osteoblastic differentiation of DFATs compared to those treated with BMP9 alone. In addition, upregulation for BMP9-receptor genes was observed by LIPUS treatment. Indomethacin, an inhibitor of prostaglandin synthesis, significantly inhibited the synergistic effect of BMP9 and LIPUS co-stimulation on osteoblastic differentiation of DFATs. LIPUS promotes BMP9 induced osteoblastic differentiation of DFATs in vitro and prostaglandins may be involved in this mechanism.

Low-intensity pulsed ultrasound irradiation attenuates collagen degradation of articular cartilage in early osteoarthritis-like model mice

PURPOSE

Osteoarthritis (OA) is a combination of degeneration and destruction of articular cartilage due to mechanical stress, secondary synovitis, and bone remodelling. In recent years, early knee OA, a preliminary stage of structural failure in OA, has attracted attention as a potential target for therapy to prevent the onset of OA. Intra-articular administration of monoiodoacetic acid (MIA) induces OA-like symptoms, and low doses of MIA induce early OA like symptoms. In this experiment, a low-dose of MIA was induced to early OA model mice, which were then irradiated with low-intensity pulsed ultrasound (LIPUS) to examine whether LIPUS improves symptoms of early OA.

METHODS

After 4 weeks of LIPUS irradiation, articular cartilage was observed at 1 and 4 weeks. The Osteoarthritis Research Society International (OARSI) scores were calculated using Safranin-O staining results. Cartilage degeneration was detected using Denatured Collagen Detection Reagent (DCDR).

RESULTS

We observed a significant decrease in OARSI scores in the LIPUS irradiated group at week 4. The non-LIPUS group showed widespread areas of double positivity for Type II collagen and DCDR, whereas the LIPUS group showed only a small number of DCDR-positive areas. In addition, macrophage numbers counted in the articular capsule at week 1 showed a significant decrease in the LIPUS irradiated group. Lubricin detection showed that lubricin positive cell number was significantly increased by LIPUS irradiation at week 4.

CONCLUSIONS

These results suggest that LIPUS attenuates cartilage degeneration in early OA by relieving inflammation and enhancing the inhibitory effect of lubricin on cartilage degeneration.

Multiscale simulation of the effect of low-intensity pulsed ultrasound on the mechanical properties distribution of osteocytes

Low-intensity pulsed ultrasound (LIPUS) is a potential effective means for the prevention and treatment of disuse osteoporosis. In this paper, the effect of LIPUS exposure on the mechanical properties distribution of the osteocyte system (osteocyte body contains nucleus, osteocyte process, and primary cilia) is simulated. The results demonstrate that the mechanical micro-environment of the osteocyte is significantly improved by ultrasound exposure, and the mean von Mises stress of the osteocyte system increases linearly with the excitation sound pressure amplitude. The mechanical effect of LIPUS on osteocytes is enhanced by the stress amplification mechanism of the primary cilia and osteocyte processes.

Low-intensity pulsed ultrasound ameliorates glia-mediated inflammation and neuronal damage in experimental intracerebral hemorrhage conditions

BACKGROUND

Intracerebral hemorrhage (ICH) is a condition associated with high morbidity and mortality, and glia-mediated inflammation is a major contributor to neurological deficits. However, there is currently no proven effective treatment for clinical ICH. Recently, low-intensity pulsed ultrasound (LIPUS), a non-invasive method, has shown potential for neuroprotection in neurodegenerative diseases. This study aimed to investigate the neuroprotective effects and potential mechanisms of LIPUS on glia-mediated inflammation in ICH.

METHODS

This study used 289 mice to investigate the effects of LIPUS on ICH. ICH was induced by injecting bacterial collagenase (type VII-S; 0.0375 U) into the striatum of the mice. LIPUS was applied noninvasively for 3 days, including a 2-h-delayed intervention to mimic clinical usage. The study evaluated neurological function, histology, brain water content, hemoglobin content, MRI, and protein expression of neurotrophic factors, inflammatory molecules, and apoptosis. In vitro studies investigated glia-mediated inflammation by adding thrombin (10 U/mL) or conditioned media to primary and cell line cultures. The PI3K inhibitor LY294002 was used to confirm the effects of PI3K/Akt signaling after LIPUS treatment.

RESULTS

LIPUS treatment improved neurological deficits and reduced tissue loss, edema, and neurodegeneration after ICH. The protective effects of LIPUS resulted from decreased glia-mediated inflammation by inhibiting PI3K/Akt-NF-κB signaling, which reduced cytokine expression and attenuated microglial activation-induced neuronal damage in vitro.

CONCLUSIONS

LIPUS treatment improved neurological outcomes and reduced glia-mediated inflammation by inhibiting PI3K/Akt-NF-κB signaling after ICH. LIPUS may provide a non-invasive potential management strategy for ICH.

Influence of Low-Intensity Pulsed Ultrasound Parameters on the Bone Mineral Density in Rat Model: A Systematic Review

OBJECTIVE

Bone recovery typically depends on the age of organisms or the prevalence of metabolic disorders such as osteoporosis, which is a metabolic condition characterized by decreased bone strength and bone mineral density (BMD). Therefore, low-intensity pulsed ultrasound (LIPUS), a non-invasive method for osteogenic stimulation, presents promising results. However, heterogeneity in animal study designs is a typical characteristic. Hence, we conducted a systematic review to evaluate the effectiveness of LIPUS in the recovery of experimental bone defects using rat models. We examined the areal and volumetric BMD to identify LIPUS doses to be applied and evaluated the accuracy reported by previous studies.

METHODS

The Virtual Health Library regional portal, PubMed, Embase, EBSCOhost, Scopus and CAPES were reviewed for animal studies that compared fracture treatments based on LIPUS with sham or no treatments using rat models and reported BMD as an outcome. The tool provided by the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) and the Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES) checklist were used to assess the bias and quality of such studies.

RESULTS

Of the six studies reviewed, the most frequently used LIPUS dose had an ultrasonic frequency of 1.0 MHz, repetition rate of 0.1 kHz and pulse duration of 2000 μs. An intensity (ISATA) of 30 mW/cm2 was the most preferred for bone recovery. However, the BMD could not solely irrefutably evaluate the effectiveness of LIPUS in bone recovery as the results were discordant with each other. The discrepancies in experimental methodologies, low-quality classifications and high risk of bias in the selected studies, however, did not validate the undertaking of a meta-analysis.

CONCLUSION

On the basis of the BMD results, no sufficient evidence was found to recommend the use of LIPUS for bone recovery in rat models. Thus, this systematic review indicates that the accuracy of such reports must be improved to improve their scientific quality to facilitate a transition of LIPUS applications from pre-clinical research to clinic use.

Evaluation of Efficacy of Low-Intensity Pulsed Ultrasound on Comorbidities Following Mandibular Impacted Third Molar Surgery: A Prospective Study

Introduction

Despite several in vitro and in vivo applications of low-intensity pulsed ultrasound (LIPUS), it remains an under-studied feature of the oral and maxillofacial region. The goal of this in vivo study was to objectively investigate the efficacy of low-intensity pulsed ultrasound on wound healing and related morbidities following surgical removal of an impacted third molar.

Materials and Methods

The following in vivo prospective, comparative, randomised controlled clinical study was carried out amongst 56 patients who reported to the Department of Oral and Maxillofacial Surgery fulfilling the inclusion criteria. Group A received sham ultrasound, whereas Group B received LIPUS therapy. Based on the group allocated LIPUS 1 MHz, pulsed 20% and dose 1.0 watts/square centimetre (W/cm2)/sham, ultrasound therapy was given on 1st, 2nd and 3rd post-operative days. The assessment of post-operative pain, oedema, trismus and wound healing on preoperative, first, third and seventh postoperative days.

Results

The quantitative variables of the study were assessed using independent sample t-test, and qualitative variables were assessed using the Chi-square test. The P < 0.05 on third and seventh post-op days for pain, trismus and wound healing in the LIPUS group compared to control group making it statistically significant. There was no statistically significant difference in the reduction of oedema amongst the two groups.

Discussion

Post-LIPUS application in the patients, postoperative pain was significantly reduced, trismus was noticeably improved and wound healing was satisfactory and can be employed as a complementary technique.

Pulsed frequency modulated ultrasound promotes therapeutic effects of osteoporosis induced by ovarian failure in mice

Low-intensity pulsed ultrasound (LIPUS) has been proved to be an effective technique for the treatment of osteoporosis. To better activate the bone formation-related markers, promote the different stages of osteogenesis, and further enhance the therapeutic effects of ultrasound, this study employed pulsed frequency modulated ultrasound (pFMUS) to treat mice with osteoporosis, which was caused by ovarian failure due to 4-vinylcyclohexene dioxide (VCD) injection. Healthy 8-week-old female C57BL/6J mice were randomly divided into four groups: Sham (S), VCD-control (V), VCD + LIPUS (VU), and VCD + pFMUS (VFU). VU and VFU groups were treated by LIPUS and pFMUS, respectively. Serum analysis, micro-computed tomography (micro-CT), mechanical testing and hematoxylin and eosin (HE) staining were performed to evaluate the therapeutic effects of ultrasound. Quantitative reverse-transcription PCR (qRT-PCR) and western blot analysis were used to explore the mechanism of ultrasound on osteoporosis. Results showed that pFMUS might have better therapeutic effects than traditional LIPUS in terms of bone microstructure and bone strength. In addition, pFMUS could promote bone formation by activating phosphoinositide-3 kinase/protein kinase B (PI3K/Akt) pathway, and slow down bone resorption by increasing osteoprotegerin/receptor activator of nuclear factor κB ligand (OPG/RANKL) ratio. This study is of positive prognostic significance when understanding the mechanism of ultrasound regulation on osteoporosis and establishing novel treatment plan of osteoporosis by multi-frequency ultrasound.

Enhanced bone regeneration by low-intensity pulsed ultrasound and lipid microbubbles on PLGA/TCP 3D-printed scaffolds

BACKGROUND

To investigate the effect of low-intensity pulsed ultrasound (LIPUS) combined with lipid microbubbles on the proliferation and bone regeneration of bone marrow mesenchymal stem cells (BMSCs) in poly (lactic-glycolic acid copolymer) (PLGA)/α-tricalcium phosphate (TCP) 3D-printed scaffolds.

METHODS

BMSCs were irradiated with different LIPUS parameters and microbubble concentrations, and the best acoustic excitation parameters were selected. The expression of type I collagen and the activity of alkaline phosphatase were detected. Alizarin red staining was used to evaluate the calcium salt production during osteogenic differentiation.

RESULTS

BMSCs proliferation was the most significant under the condition of 0.5% (v/v) lipid microbubble concentration, 2.0 MHz frequency, 0.3 W/cm² sound intensity and 20% duty cycle. After 14 days, the type I collagen expression and alkaline phosphatase activity in the scaffold increased significantly compared to those in the control group, and alizarin red staining showed more calcium salt production during osteogenic differentiation. After 21 days, scanning electron microscopy experiments showed that osteogenesis was obvious in the PLGA/TCP scaffolds.

CONCLUSION

LIPUS combined with lipid microbubbles on PLGA/TCP scaffolds can promote BMSCs growth and bone differentiation, which is expected to provide a new and effective method for the treatment of bone regeneration in tissue engineering.

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.

A Quantitative Study of Thermal and Non-thermal Mechanisms in Ultrasound-Induced Nano-drug Delivery

OBJECTIVE

The primary objective of this study was to quantify the contributions to drug release for thermal and non-thermal mechanisms in ultrasound-induced release from gold nanoparticles (GNPs) for the first time.

METHODS

We studied doxorubicin (DOX) and curcumin release from the surface of GNPs using two different methods to induce drug release in an ex vivo tissue model: (i) localized tissue heating with a water bath and (ii) low-intensity pulsed ultrasound (LIPUS) exposure. Both methods have similar temperature profiles and can induce the release of both hydrophobic (curcumin) and hydrophilic (DOX) drugs from the surface of GNPs. Quantitative drug release in both cases was compared via fluorescence measurements.

DISCUSSION

The water bath heating method induced drug release using thermal effects only, whereas LIPUS exposure induced drug release used a combination of thermal and non-thermal mechanisms. It was found that there were increases of 70 ± 16% (curcumin) and 127 ± 20% (DOX) in drug release when LIPUS was used to induce drug release (both thermal and non-thermal mechanisms) as compared with the water bath (thermal mechanisms only) mediated release.

CONCLUSION

We determined that non-thermal mechanisms account for 41 ± 3% of curcumin release and 56 ± 4% of DOX release. It was concluded that in our ex vivo tissue model, the non-thermal mechanisms play a significant role in LIPUS-induced drug release from GNP drug carriers and that the contributions of non-thermal mechanisms to drug release depend on the type of anticancer drug loaded on the GNP surface.

Noninvasive ultrasound stimulation to treat myocarditis through splenic neuro-immune regulation

BACKGROUND

The cholinergic anti-inflammatory pathway (CAP) has been widely studied to modulate the immune response. Current stimulating strategies are invasive or imprecise. Noninvasive low-intensity pulsed ultrasound (LIPUS) has become increasingly appreciated for targeted neuronal modulation. However, its mechanisms and physiological role on myocarditis remain poorly defined.

METHODS

The mouse model of experimental autoimmune myocarditis was established. Low-intensity pulsed ultrasound was targeted at the spleen to stimulate the spleen nerve. Under different ultrasound parameters, histological tests and molecular biology were performed to observe inflammatory lesions and changes in immune cell subsets in the spleen and heart. In addition, we evaluated the dependence of the spleen nerve and cholinergic anti-inflammatory pathway of low-intensity pulsed ultrasound in treating autoimmune myocarditis in mice through different control groups.

RESULTS

The echocardiography and flow cytometry of splenic or heart infiltrating immune cells revealed that splenic ultrasound could alleviate the immune response, regulate the proportion and function of CD4+ Treg and macrophages by activating cholinergic anti-inflammatory pathway, and finally reduce heart inflammatory injury and improve cardiac remodeling, which is as effective as an acetylcholine receptor agonists GTS-21. Transcriptome sequencing showed significant differential expressed genes due to ultrasound modulation.

CONCLUSIONS

It is worth noting that the ultrasound therapeutic efficacy depends greatly on acoustic pressure and exposure duration, and the effective targeting organ was the spleen but not the heart. This study provides novel insight into the therapeutic potentials of LIPUS, which are essential for its future application.

Effect of low-intensity pulsed ultrasound on osteogenic differentiation of human induced membrane-derived cells in Masquelet technique

INTRODUCTION

The Masquelet technique is a relatively new method for large bone defect treatment. In this technique, grafted bone tissue is used, and after the cement is removed, the induced membrane (IM; that form around the cement spacers placed in the bone defect region) is thought to play an important role in promoting bone formation. On the other hand, low-intensity pulsed ultrasound (LIPUS) is known to promote fracture healing and angiogenesis through mechanical stimulation. This study aimed to investigate the in vitro effects of LIPUS on the osteogenic differentiation of human induced membrane-derived cells (IMCs).

METHODS

Seven patients who had been treated using the Masquelet technique were enrolled. The IM was harvested during the second stage of the technique. IMCs were isolated, cultured in growth medium, and then divided into two groups: (1) control group, IMCs cultured in osteogenic medium without LIPUS, and (2) LIPUS group, IMCs cultured in osteogenic medium with LIPUS treatment. Adherent cells from the IM samples were harvested after the first passage and evaluated for cell surface protein expression using immunostaining. A cell proliferation assay was used to count the number of IMCs using a hemocytometer. Osteogenic differentiation capability was assessed using an alkaline phosphatase (ALP) activity assay, Alizarin Red S staining, and real-time reverse transcription-polymerase chain reaction.

RESULTS

Cell surface antigen profiling revealed that the IMCs contained cells positive for the mesenchymal stem cell-related markers CD73, CD90, and CD105. No significant difference in cell numbers was found between the control and LIPUS groups. The ALP activity of IMCs in the LIPUS group was significantly higher than that in the control group on days 7 and 14. Alizarin red S staining intensity was significantly higher in the LIPUS group than in the control group on day 21. Runx2 and VEGF expression was significantly upregulated on days 7 and 14, respectively, compared with levels in the control group.

CONCLUSION

We demonstrated the significant effect of LIPUS on the osteogenic differentiation of human IMCs. This study indicates that LIPUS can be used as an additional tool for the enhancement of the healing process of the Masquelet technique.

Therapeutic strategy for atypical ulnar fracture in long use of bisphosphonate: A systematic review

BACKGROUND

Atypical fractures are caused by the combined effects of severe suppression of bone metabolism (SSBT) due to long-term bisphosphonate therapy and chronic repetitive bone microdamage. Atypical ulnar fractures (AUFs) due to SSBT are rare, and there is no standard treatment strategy for such fractures. The relevant literature was reviewed, and the treatment strategy for AUF is discussed.

METHODS

A systematic review was conducted. All studies on ulnar fractures in individuals with a history of bisphosphonate use were included, and the data were extracted and analyzed from the perspective of the therapeutic strategy.

RESULTS

Forty limbs of 35 patients were included. As for the treatment of AUF, 31 limbs were treated surgically, and conservative treatment with casting was performed for 9 limbs. The bone fusion rate was 22/40 (55.0%), and non-union was seen in all patients treated conservatively. There was a significant difference in the bone fusion rate between patients with surgical treatment and those with conservative treatment. The bone fusion rate of patients with parathyroid hormone (PTH) and surgery was 82.3% (14/17 limbs); the bone fusion rate with PTH and bone graft was 69.2% (9/13 limbs). However, there were no significant differences in the fusion rate in the groups with or without PTH, with or without bone grafting, or the combination of the two treatments. There was also no significant difference in the bone fusion rate in the groups with or without low-intensity pulsed ultrasound (LIPUS) treatment.

CONCLUSIONS

Based on the literature review, surgery is necessary to achieve bone union, but surgery alone is not adequate to achieve bony union. Bone grafting and the administration of PTH and LIPUS may promote early bone fusion, but the present study did not show significant advantages of these additional treatments for bone union.

An exploratory clinical trial for concentrated autologous bone marrow aspirate transplantation in the treatment of osteonecrosis of the femoral head

PURPOSE

This study evaluated the efficacy and safety of a novel treatment for osteonecrosis, in which concentrated autologous bone marrow aspirate transplantation (CABMAT) is followed by low-intensity pulsed ultrasound (LIPUS) stimulation for 3 months. The study was designed as a prospective, uncontrolled, open-label phase II clinical study.

METHODS

This study included 16 cases of osteonecrosis of the femoral head (ONFH), including 26 hips. Patients were transplanted with concentrated bone marrow and periodically evaluated for infection and neoplasm development. Moreover, clinical and radiological examinations were conducted to confirm the treatment efficacy.

RESULTS

No infections were observed during the course of this study nor tumours developed at the treatment site 24 months after transplantation. At a mean 48 (30-56) months post-transplantation, the onset or progression of collapse was noted in four hips, of which one hip underwent total hip arthroplasty.

CONCLUSION

Treatment with CABMAT combined with 3-month LIPUS stimulation was safe, and further randomised clinical studies are needed to determine the efficacy and feasibility of this treatment.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN000020940, 9/2/2016).

Low-intensity pulsed ultrasound (LIPUS) enhances the anti-inflammatory effects of bone marrow mesenchymal stem cells (BMSCs)-derived extracellular vesicles

BACKGROUND

Bone marrow-derived mesenchymal stem cells (BMSCs)-derived extracellular vesicles (EVs) have shown potent anti-inflammatory function in various pathological conditions, such as osteoarthritis and neurodegenerative diseases. Since the number of EVs naturally secreted by cells is finite and they usually bear specific repertoires of bioactive molecules to perform manifold cell-cell communication, but not one particular therapeutic function as expected, their practical application is still limited. Strategies are needed to increase the production of EVs and enhance their therapeutic function. Recent studies have suggested that low-intensity pulsed ultrasound (LIPUS) is a promising non-invasive method to increase the secretion of EVs and promote their anti-inflammatory effects. However, the effect of LIPUS stimulation of BMSCs on EVs derived from the cells remains unclear. The objective of this study was to investigate whether LIPUS stimulation on BMSCs could increase the secretion of EVs and enhance their anti-inflammatory effects.

METHODS

BMSCs were exposed to LIPUS (300 mW/cm²) for 15 min and EVs were isolated by ultracentrifugation. Anti-inflammatory effects of EVs were investigated on RAW264.7 cells in vitro and in the allogeneic skin transplantation model. Small RNA-seq was utilized to identify components difference in EVs with/without LIPUS irradiation.

RESULTS

In this study, we found that LIPUS stimulation could lead to a 3.66-fold increase in the EVs release from BMSCs. Moreover, both in vitro and in vivo experimental results suggested that EVs secreted from LIPUS-treated BMSCs (LIPUS-EVs) possessed stronger anti-inflammatory function than EVs secreted from BMSCs without LIPUS stimulation (C-EVs). RNA-seq analysis revealed that miR-328-5p and miR-487b-3p were significantly up-regulated in LIPUS-EVs compare with C-EVs. The suppression of MAPK signaling pathway by these two up-regulated miRNAs could be the potential mechanism of strengthened anti-inflammatory effects of LIPUS-EVs.

CONCLUSION

LIPUS stimulation on BMSCs could significantly increase the secretion of EVs. Moreover, EVs generated from LIPUS-treated BMSCs possessed much stronger anti-inflammatory function than C-EVs. Therefore, LIPUS could be a promising non-invasive strategy to promote the production of EVs from BMSCs and augment their anti-inflammatory effects.

Low-intensity pulsed ultrasound promotes skeletal muscle regeneration via modulating the inflammatory immune microenvironment

Background: Low-intensity pulsed ultrasound (LIPUS, a form of mechanical stimulation) can promote skeletal muscle functional repair, but a lack of mechanistic understanding of its relationship and tissue regeneration limits progress in this field. We investigated the hypothesis that specific energy levels of LIPUS mediates skeletal muscle regeneration by modulating the inflammatory microenvironment. Methods: To address these gaps, LIPUS irritation was applied in vivo for 5 min at two different intensities (30mW/cm² and 60mW/cm²) in next 7 consecutive days, and the treatment begun at 24h after air drop-induced contusion injury. In vitro experiments, LIPUS irritation was applied at three different intensities (30mW/cm², 45mW/cm², and 60mW/cm²) for 2 times 24h after introduction of LPS in RAW264.7. Then, we comprehensively assessed the functional and histological parameters of skeletal muscle injury in mice and the phenotype shifting in macrophages through molecular biological methods and immunofluorescence analysis both in vivo and in vitro. Results: We reported that LIPUS therapy at intensity of 60mW/cm² exhibited the most significant differences in functional recovery of contusion-injured muscle in mice. The comprehensive functional tests and histological analysis in vivo indirectly and directly proved the effectiveness of LIPUS for muscle recovery. Through biological methods and immunofluorescence analysis both in vivo and in vitro, we found that this improvement was attributable in part to the clearance of M1 macrophages populations and the increase in M2 subtypes with the change of macrophage-mediated factors. Depletion of macrophages in vivo eliminated the therapeutic effects of LIPUS, indicating that improvement in muscle function was the result of M2-shifted macrophage polarization. Moreover, the M2-inducing effects of LIPUS were proved partially through the WNT pathway by upregulating FZD5 expression and enhancing β-catenin nuclear translocation in macrophages both in vitro and in vivo. The inhibition and augment of WNT pathway in vitro further verified our results. Conclusion: LIPUS at intensity of 60mW/cm² could significantly promoted skeletal muscle regeneration through shifting macrophage phenotype from M1 to M2. The ability of LIPUS to direct macrophage polarization may be a beneficial target in the clinical treatment of many injuries and inflammatory diseases.

Low-intensity pulsed ultrasound/nanomechanical force generators enhance osteogenesis of BMSCs through microfilaments and TRPM7

BACKGROUND

Low-intensity pulsed ultrasound (LIPUS) has been reported to accelerate fracture healing, but the mechanism is unclear and its efficacy needs to be further optimized. Ultrasound in combination with functionalized microbubbles has been shown to induce local shear forces and controllable mechanical stress in cells, amplifying the mechanical effects of LIPUS. Nanoscale lipid bubbles (nanobubbles) have high stability and good biosafety. However, the effect of LIPUS combined with functionalized nanobubbles on osteogenesis has rarely been studied.

RESULTS

In this study, we report cyclic arginine-glycine-aspartic acid-modified nanobubbles (cRGD-NBs), with a particle size of ~ 500 nm, able to actively target bone marrow mesenchymal stem cells (BMSCs) via integrin receptors. cRGD-NBs can act as nanomechanical force generators on the cell membrane, and further enhance the BMSCs osteogenesis and bone formation promoted by LIPUS. The polymerization of actin microfilaments and the mechanosensitive transient receptor potential melastatin 7 (TRPM7) ion channel play important roles in BMSCs osteogenesis promoted by LIPUS/cRGD-NBs. Moreover, the mutual regulation of TRPM7 and actin microfilaments promote the effect of LIPUS/cRGD-NBs. The extracellular Ca^2 + influx, controlled partly by TRPM7, could participated in the effect of LIPUS/cRGD-NBs on BMSCs.

CONCLUSIONS

The nanomechanical force generators cRGD-NBs could promote osteogenesis of BMSCs and bone formation induced by LIPUS, through regulation TRPM7, actin cytoskeleton, and intracellular calcium oscillations. This study provides new directions for optimizing the efficacy of LIPUS for fracture healing, and a theoretical basis for the further application and development of LIPUS in clinical practice.

Ca2+ signaling-mediated low-intensity pulsed ultrasound-induced proliferation and activation of motor neuron cells

Motor neuron diseases (MND) including amyotrophic lateral sclerosis and Parkinson disease are commonly neurodegenerative, causing a gradual loss of nerve cells and affecting the mechanisms underlying changes in calcium (Ca²⁺)-regulated dendritic growth. In this study, the NSC-34 cell line, a population of hybridomas generated using mouse spinal cord cells with neuroblastoma, was used to investigate the effect of low-intensity pulsed ultrasound (LIPUS) as part of an MND treatment model. After NSC-34 cells were seeded for 24 h, LIPUS stimulation was performed on the cells at days 1 and 3 using a non-focused transducer at 1.15 MHz for 8 min. NSC-34 cell proliferation and morphological changes were observed at various LIPUS intensities and different combinations of Ca²⁺ channel blockers. The nuclear translocation of Ca²⁺-dependent transcription factors was also examined. We observed that the neurite outgrowth and cell number of NSC-34 significantly increased with LIPUS stimulation at days 2 and 4, which may be associated with the treatment's positive effect on the activation of Ca²⁺-dependent transcription factors, such as nuclear factor of activated T cells and nuclear factor-kappa B. Our findings suggest that the LIPUS-induced Ca²⁺ signaling and transcription factor activation facilitate the morphological maturation and proliferation of NSC-34 cells, presenting a promising noninvasive method to improve stimulation therapy for MNDs in the future.

Advances in the application of low-intensity pulsed ultrasound to mesenchymal stem cells

Mesenchymal stem cells (MSCs) are stem cells that exhibit self-renewal capacity and multi-directional differentiation potential. They can be extracted from the bone marrow and umbilical cord, as well as adipose, amnion, and other tissues. They are widely used in tissue engineering and are currently considered an important source of cells in the field of regenerative medicine. Since certain limitations, such as an insufficient cell source, mature differentiation, and low transplantation efficiency, are still associated with MSCs, researchers have currently focused on improving the efficacy of MSCs. Low-intensity pulsed ultrasound (LIPUS) has mechanical, cavitation, and thermal effects that can produce different biological effects on organs, tissues, and cells. It can be used for fracture treatment, cartilage repair, and stem cell applications. An in-depth study of the role and mechanism of action of LIPUS in MSC treatment would promote our understanding of LIPUS and promote research in this field. In this article, we have reviewed the progress in research on the use of LIPUS with various MSCs and comprehensively discussed the progress in the use of LIPUS for promoting the proliferation, differentiation, and migration of MSCs, as well as its future prospects.

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 Promotes Repair of 4-Vinylcyclohexene Diepoxide-Induced Premature Ovarian Insufficiency in SD Rats

Women with premature ovarian insufficiency (POI) may be more vulnerable to a variety of health risks. To seek a new method to treat the disease, the effects of low-intensity pulsed ultrasound (LIPUS) on promoting repair of ovarian injury in female SD rats induced by 4-vinylcyclohexene diepoxide (VCD) were explored in this research. A total of 24 female SD rats were subjected to intraperitoneal injection of VCD to induce POI. Successful modeling was achieved in 22 rats, which were then randomized into VCD + LIPUS group (n = 13) and VCD group (n = 9). The control group (n = 5) was injected with equal normal saline. Hematoxylin and eosin staining, enzyme-linked immunosorbent assay, Western blot analysis, scanning electron microscope, immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated nick end labeling assay were applied to detect the results. The results indicated that rats in the VCD group showed disorder in the estrous cycle, the number of atresia follicles and apoptosis granulosa cells increased (p < .05). After the LIPUS treatment, the estrous cycle recovered, the number of follicles increased (p < .05), the level of E2 and anti-Müllerian hormone enhanced (p < .05), and the follicle-stimulating hormone decreased (p < .05). The expression of NF-κB p65, TNFα, Bax, ATF4, and caspase-3 in ovarian tissue was significantly decreased (p < .05). These findings showed that LIPUS could promote the repair of the VCD-induced ovarian damage in SD rats, which has the potential to be further applied in the clinic.

Low-Intensity Pulsed Ultrasound Promotes Osteogenic Differentiation of Reamer-Irrigator-Aspirator Graft-Derived Cells in Vitro

Recently, reamer-irrigator-aspirator (RIA) systems have been increasingly used to harvest autologous bone grafts. RIA graft materials contain bone marrow, which provides a viable source to derive large numbers of mesenchymal stem cells. Low-intensity pulsed ultrasound (LIPUS) significantly accelerates the differentiation of stem cells derived from bone marrow. This in vitro study investigated the effect of LIPUS on the osteogenic activity and differentiation of RIA graft-derived cells. A small amount of RIA graft was obtained from seven patients. After the cells derived from RIA grafts were cultured, they were divided into two groups: the LIPUS and control groups. LIPUS was applied once daily for 20 min (1.5 MHz, pulse duration: 200 µs, pulse repetition rate: 1 kHz, spatial average-temporal average intensity: 30 mW/cm²). Alkaline phosphatase activity (113.4% and 130.1% on days 7 and 14), expression of osteoblast-related genes (ALP, Runx2) and mineralization (135.2% on day 21) of the RIA graft-derived cells were significantly higher in the LIPUS group than in the control group. However, LIPUS did not affect the cell proliferation of RIA graft-derived cells. This study indicates that LIPUS may enhance the healing of non-union and critical bone defects treated by autologous bone grafting using the RIA system.

Potential Application of Low-Intensity Pulsed Ultrasound in Delaying Aging for Mice

INTRODUCTION

The low-intensity pulsed ultrasound (LIPUS) is one of the popular treatment modalities allowing to boost the proliferation, differentiation, and migratory activity of cells, which might be a powerful strategy for anti-aging. Seeking a novel setup for LIPUS would benefit the development of ultrasound therapeutics.

METHODS

Here, we proposed a novel underwater exposure setup of LIPUS. C57BL/6 mice were reared in the designated age-groups, which consisted of a middle-aged group (12-14 months) and an old-age group (20-23 months). The age-related changes of body composition, imbalance of energy supply and demand, imbalance of signal network maintaining internal stability, and representative phenotypes of neurodegeneration and neuroplasticity with the presence and absence of underwater LIPUS in middle-aged and aged groups were evaluated.

RESULTS

The results showed that there were obvious aging changes, imbalance of energy supply and demand, imbalance of signal network maintaining homeostasis, neurodegeneration, and damage of neural plasticity in the middle-aged and aged group with or without the LIPUS. Although middle-aged group and aged group responded differently to LIPUS, they mostly generated positive results in relieving bone loss, improving ovarian structure, regulated immune system, and enhanced endurance ability, which should have declined over age.

DISCUSSION

These findings indicate that underwater extracorporeal LIPUS exposure could be employed as single or combined anti-aging strategies that generated positive outcomes against the process of aging.

Improved activity of MC3T3-E1 cells by the exciting piezoelectric BaTiO3/TC4 using low-intensity pulsed ultrasound

Developing bioactive materials for bone implants to enhance bone healing and bone growth has for years been the focus of clinical research. Barium titanate (BT) is an electroactive material that can generate electrical signals in response to applied mechanical forces. In this study, a BT piezoelectric ceramic coating was synthesized on the surface of a TC4 titanium alloy, forming a BT/TC4 material, and low-intensity pulsed ultrasound (LIPUS) was then applied as a mechanical stimulus. The combined effects on the biological responses of MC3T3-E1 cells were investigated. Results of scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction showed that an uniform nanospheres -shaped BT coating was formed on TC4 substrate. Piezoelectric behaviors were observed using piezoelectric force microscopy with the piezoelectric coefficient d33 of 0.42 pC/N. Electrochemical measures indicated that LIPUS-stimulated BT/TC4 materials could produce a microcurrent of approximately 10 μA/cm2. In vitro, the greatest osteogenesis (cell adhesion, proliferation, and osteogenic differentiation) was found in MC3T3-E1 cells when BT/TC4 was stimulated using LIPUS. Furthermore, the intracellular calcium ion concentration increased in these cells, possibly because opening of the L-type calcium ion channels was promoted and expression of the CaV1.2 protein was increased. Therefore, the piezoelectric BT/TC4 material with LIPUS loading synergistically promoted osteogenesis, rending it a potential treatment for early stage formation of reliable bone-implant contact.

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.

Low-intensity pulsed ultrasound inhibits fibroblast-like synoviocyte proliferation and reduces synovial fibrosis by regulating Wnt/β-catenin signaling

OBJECTIVE

Synovial fibrosis is a characteristic symptom of osteoarthritis (OA), which is closely associated with joint pain and stiffness. Previous studies have reported that low-intensity pulsed ultrasound (LIPUS) can alleviate cartilage degradation in OA. However, the functions and mechanisms of LIPUS in OA synovial fibrosis are still unknown.

METHODS

The destabilization of the medial meniscus (DMM) mouse model of OA was established in C57 male mice and fibroblast-like synoviocytes (FLS) were isolated from synovial tissue of OA patients. The knee joint diameter, Masson's trichrome (MT) and Hematoxylin-eosin (HE) staining were used to evaluate synovial fibrosis and hyperplasia. The Immunohistochemistry (IHC) staining was performed to detected the expression of synovial fibrosis makers and the activation of Wnt/β-catenin signaling in vivo. FLS were treated with TGF-β1 to serve as an in vitro model of synovial fibrosis, Wnt3a was used to activate the Wnt/β-catenin signaling in cells. Cell proliferation was detected by using EdU assay, cell viability was performed by CCK8 assay. The protein levels of α-SMA, CTGF, Col Ⅰ, β-catenin, active β-catenin, c-Myc and cyclin D1 were examined by western blot and immunofluorescence staining.

RESULTS

Two weeks after the LIPUS treatment, the synovial fibrosis, synovial hyperplasia and synoviocyte proliferation in the DMM model were significantly decreased. In vitro, LIPUS directly inhibited the TGF-β1-induced fibrotic response and proliferation of FLS. Meanwhile, LIPUS suppressed Wnt/β-catenin signaling in the synovium of DMM mice and cultured FLS. More importantly, we found that the synovial fibrosis makers, Wnt/β-catenin pathway downstream proteins and FLS proliferation were significantly decreased in Wnt3a-stimulated FLS following LIPUS treatment.

CONCLUSIONS

Our results present a novel role of LIPUS in OA-related synovial fibrosis, which is associated with its ability to repress Wnt/β-catenin signaling in FLS.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study provides new insight into the clinical application of LIPUS as a therapeutic option to manage synovial fibrosis in OA.

Can low-intensity pulsed ultrasound (LIPUS) accelerate bone healing after intramedullary screw fixation for proximal fifth metatarsal stress fractures? A retrospective study

Background

Intramedullary screw fixation is considered the standard treatment for proximal fifth metatarsal stress fractures. Low-intensity pulsed ultrasound (LIPUS) is a well-known bone-healing enhancement device. However, to the best of our knowledge, no clinical study has focused on the effect of LIPUS for postoperative bone union in proximal fifth metatarsal stress fractures. This study aimed to investigate the effect of LIPUS treatment after intramedullary screw fixation for proximal fifth metatarsal stress fractures.

Methods

Between January 2015 and March 2020, patients who underwent intramedullary screw fixation for proximal fifth metatarsal stress fractures were investigated retrospectively. All patients underwent intramedullary screw fixation using a headless compression screw with autologous bone grafts from the base of the fifth metatarsal. The time to restart running and return to sports, as well as that for radiographic bone union, were compared between groups with or without LIPUS treatment. LIPUS treatment was initiated within 3 weeks of surgery in all cases.

Results

Of the 101 ft analyzed, 57 ft were assigned to the LIPUS treatment group, and 44 ft were assigned to the non-LIPUS treatment group. The mean time to restart running and return to sports was 6.8 and 13.7 weeks in the LIPUS treatment group and was 6.2 and 13.2 weeks in the non-LIPUS treatment group, respectively. There were no significant differences in these parameters between groups. In addition, the mean time to radiographic bone union was not significantly different between the LIPUS treatment group (11.9 weeks) and the non-LIPUS treatment group (12.0 weeks). The rate of postoperative nonunion in the LIPUS treatment group was 0% (0/57), while that in the non-LIPUS treatment group was 4.5% (2/44). However, this difference was not statistically significant.

Conclusions

There were no statistically significant differences regarding the time to start running, return to sports, and radiographic bone union in patients with or without LIPUS treatment after intramedullary screw fixation for proximal fifth metatarsal stress fractures. Therefore, we cannot recommend the routine use of LIPUS to shorten the time to bone union after intramedullary screw fixation for proximal fifth metatarsal stress fractures.

Neuroprotective Effect of Low-Intensity Pulsed Ultrasound on the Mouse MPTP/MPP+ Model of Dopaminergic Neuron Injury

Ultrasound mediated neuromodulation has been demonstrated to a safe treatment strategy in the field of neuroscience. In this study, low-intensity pulsed ultrasound (LIPUS) was used to treat Parkinson's disease (PD) models induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (MPP⁺) to explore the possibility of ultrasound neuroprotective effect on PD. The results demonstrated that LIPUS treatment can attenuate the central neurotoxicity of MPTP in mice, reduce the loss of tyrosine hydroxylase positive neurons in the substantia nigra pars compacta and decrease the apoptosis in the section of substantia nigra. The movement and balance dysfunctions in PD mice were improved with LIPUS treatment. In addition, we demonstrated that LIPUS can inhibit the decreased activity and increased apoptosis of dopaminergic neurons induced by MPP⁺, restrain the accumulation of reactive oxygen species (ROS) and decrease of mitochondrial membrane potential caused by MPP⁺. Moreover, LIPUS stimulation alone did not cause any cytotoxicity and tissue damage in our study. Taken together, the protective and regulatory effects of LIPUS on dopaminergic neurons make it possible as a new, safe and noninvasive treatment for PD.

Therapeutic Effects of Low-Intensity Pulsed Ultrasound on Premature Ovarian Insufficiency

We explored the therapeutic effects of low-intensity pulsed ultrasound (LIPUS) on a rat model of ovarian damage induced by cyclophosphamide. A total of 44 female rats with premature ovarian insufficiency induced by cyclophosphamide were randomly divided into two groups (an ultrasound group and a control group); 22 normal rats without premature ovarian insufficiency were also included as a third group. The ultrasound group was treated with LIPUS, while the other two groups received the same treatment but without any power output. We monitored the estrous cycles of all rats. Seven days after treatment, 21 rats were selected to mate with male rats. We then recorded the pregnancy rate along with the number and weight of newborn rats per nest. We collected samples of blood, uterus and ovaries from the remaining 45 rats before they were sacrificed. Compared with the normal group, the control group exhibited disordered estrous cycles, more atretic follicles (p < 0.01), higher levels of serum follicle-stimulating hormone (p < 0.01), fewer other follicles (p < 0.01) and lower serum levels of E₂ and anti-Müllerian hormone (p < 0.01). Compared with the control group, the ultrasound group had normal estrous cycles with fewer atretic follicles (p < 0.01), lower levels of serum follicle-stimulating hormone (p < 0.01), more other follicles (p < 0.01) and higher levels of serum E₂ (p < 0.01). No significant difference in the levels of serum anti-Müllerian hormone was noted between the control group and the ultrasound group. No significant differences were observed between the three groups with respect to pregnancy rate or the number and weight of newborns per nest (p > 0.05). In conclusion, our data indicate that LIPUS could improve some ovarian functions of rats with premature ovarian insufficiency.

Low-Intensity Pulsed Ultrasound Enhanced Neurite Guidance Growth through Netrin-1/DCC Signal Pathway in Primary Cultured Cortical Neurons of Rats

Low-intensity pulsed ultrasound is found to be effective in axonal regeneration, while the role of ultrasound in axonal growth guidance is still unclear. This study was performed to explore the neuroprotective role of low-intensity pulsed ultrasound (US) both in vitro and in vivo. Primary cultured rat cortical neurons were subjected to 1.0 MHz ultrasound for 5 min every day at intensity of 0, 0.008, 0.12, and 0.21 W/cm². Our results demonstrated that low-intensity pulsed ultrasound significantly increased neuronal cell viability and inhibited neuronal apoptosis in vitro as determined by fluorescein diacetate assay (FDA) and a TdT-mediated biotin-dUTP nicked-end labeling (TUNEL) assay. Moreover, low-intensity pulsed ultrasound at 0.12 W/cm² significantly enhanced the axonal growth guidance by activation of netrin-1 and DCC (deleted in colorectal carcinoma) expression as determined by Western blots assay. More interestingly, we further found that low-intensity pulsed ultrasound treatment at 0.21 W/cm² promoted the functional restoration of rat injured nerves in vivo, decreased hemorrhage, and reversed the injury process by activating positive netrin-1 expression as seen in the immunohistochemistry (IHC) assay. Thus, our study strongly demonstrated that low-intensity pulsed ultrasound activated netrin-1/DCC signaling and further mediated neurite outgrowth. It would be a new approach to nerve regeneration in the future.

Low-Intensity Pulsed Ultrasound Prompts Both Functional and Histologic Improvements While Upregulating the Brain-Derived Neurotrophic Factor Expression after Sciatic Crush Injury in Rats

The aim of this study was to determine that low-intensity pulsed ultrasound (LIPUS) at an intensity of 140 mW/cm² promotes functional and histologic improvements in sciatic nerve crush injury in a rat model and to investigate changes over time in relevant growth factors and receptors, exploring the mechanism of LIPUS in the recovery process after injury. Toe angle in the toe-off phase, regenerative axonal length, myelinated nerve fiber density, diameter of myelinated nerve fiber, axon diameter and myelin sheath thickness were significantly higher in the LIPUS group than in the sham group. Gene and protein expression of brain-derived neurotrophic factor (BDNF) was upregulated in the LIPUS group. In conclusion, LIPUS contributed to rapid functional and histologic improvement and upregulated BDNF expression after sciatic nerve crush injury in rats.

Enhanced bone formation of calvarial bone defects by low-intensity pulsed ultrasound and recombinant human bone morphogenetic protein-9: a preliminary experimental study in rats

OBJECTIVES

The aim of this study was to evaluate the combined effects of recombinant human bone morphogenetic protein - 9 (rhBMP-9) loaded onto absorbable collagen sponges (ACS) and low-intensity pulsed ultrasound (LIPUS) on bone formation in rat calvarial defects.

MATERIALS AND METHODS

Circular calvarial defects were surgically created in 18 Wistar rats, which were divided into LIPUS-applied (+) and LIPUS-non-applied (-) groups. The 36 defects in each group received ACS implantation (ACS group), ACS with rhBMP-9 (rhBMP-9/ACS group), or surgical control (control group), yielding the following six groups: ACS (+/-), rhBMP-9/ACS (+/-), and control (+/-). The LIPUS-applied groups received daily LIPUS exposure starting immediately after surgery. At 4 weeks, animals were sacrificed and their defects were investigated histologically and by microcomputed tomography.

RESULTS

Postoperative clinical healing was uneventful at all sites. More new bone was observed in the LIPUS-applied groups compared with the LIPUS-non-applied groups. Newly formed bone area (NBA)/total defect area (TA) in the ACS (+) group (46.49 ± 7.56%) was significantly greater than that observed in the ACS (-) (34.31 ± 5.68%) and control (-) (31.13 ± 6.74%) groups (p < 0.05). The rhBMP-9/ACS (+) group exhibited significantly greater bone volume, NBA, and NBA/TA than the rhBMP-9/ACS (-) group (2.46 ± 0.65 mm³ vs. 1.76 ± 0.44 mm³, 1.25 ± 0.31 mm² vs. 0.88 ± 0.22 mm², and 62.80 ± 11.87% vs. 42.66 ± 7.03%, respectively) (p < 0.05). Furthermore, the rhBMP-9/ ACS (+) group showed the highest level of bone formation among all groups.

CONCLUSION

Within their limits, it can be concluded that LIPUS had osteopromotive potential and enhanced rhBMP-9-induced bone formation in calvarial defects of rats.

CLINICAL RELEVANCE

The use of rhBMP-9 with LIPUS stimulation can be a potential bone regenerative therapy for craniofacial/peri-implant bone defects.