Low-intensity pulsed ultrasound induces cartilage matrix synthesis and reduced MMP13 expression in chondrocytes

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.

Effectiveness of low-intensity pulsed ultrasound on osteoarthritis: molecular mechanism and tissue engineering

Osteoarthritis (OA) is distinguished by pathological alterations in the synovial membrane, articular cartilage, and subchondral bone, resulting in physical symptoms such as pain, deformity, and impaired mobility. Numerous research studies have validated the effectiveness of low-intensity pulsed ultrasound (LIPUS) in OA treatment. The periodic mechanical waves generated by LIPUS can mitigate cellular ischemia and hypoxia, induce vibration and collision, produce notable thermal and non-thermal effects, alter cellular metabolism, expedite tissue repair, improve nutrient delivery, and accelerate the healing process of damaged tissues. The efficacy and specific mechanism of LIPUS is currently under investigation. This review provides an overview of LIPUS's potential role in the treatment of OA, considering various perspectives such as the synovial membrane, cartilage, subchondral bone, and tissue engineering. It aims to facilitate interdisciplinary scientific research and further exploration of LIPUS as a complementary technique to existing methods or surgery. Ongoing research is focused on determining the optimal dosage, frequency, timing, and treatment strategy of LIPUS for OA. Additional research is required to clarify the precise mechanism of action and potential impacts on cellular, animal, and human systems prior to its integration into therapeutic applications.

The Effect of Low-Intensity Pulsed Ultrasound on Temporomandibular Joint Arthritis in Juvenile Rats

Juvenile idiopathic arthritis is an inflammatory disease that can affect the temporomandibular joint (TMJ) and lower jaw growth. Better treatment options are needed, so this study investigated the effect of low-intensity pulsed ultrasound (LIPUS) on TMJ arthritis. Seventy-two 3-week-old male Wistar rats were in vivo microcomputed tomography (micro-CT) scanned and divided into eight groups (n = 9). These groups were Group 1-TMJ arthritis and immediate LIPUS treatment (20 min/day, 4 weeks); Group 2-immediate LIPUS treatment and no TMJ arthritis; Group 3-TMJ arthritis and no LIPUS; Group 4-no TMJ arthritis and no LIPUS; Group 5-TMJ arthritis and LIPUS treatment with a delayed start by 4 weeks; Group 6-Delayed LIPUS and no TMJ arthritis; Group 7-TMJ arthritis and no (delayed) LIPUS; and Group 8-no TMJ arthritis and no (delayed) LIPUS. Ex vivo micro-CT scanning was completed, and samples were prepared for tissue analysis. Synovitis was observed in the TMJ arthritis (collagen-induced arthritis [CIA]) groups, but the severity appeared greater in the groups without LIPUS treatment. Fibrocartilage and hypertrophic cell layer thicknesses in the CIA group without LIPUS treatment were significantly greater (p < 0.05). Proteoglycan staining appeared greater in the LIPUS groups. Immediate LIPUS treatment increased the expression of type II collagen, type X collagen, and transforming growth factor-beta 1 (TGF-β1) immunostaining, and CIA (no LIPUS) increased MMP-13, vascular endothelial growth factor, and interleukin-1 beta (IL-1β) immunostaining. LIPUS treatment prevented growth disturbances observed in the CIA groups (no LIPUS) (p < 0.005). Our results have contributed to the understanding of the uses and limitations of the CIA juvenile rat model and have demonstrated the effects of LIPUS on the TMJ and mandibular growth. This information will help in designing future studies for investigating LIPUS and TMJ arthritis, leading to the development of new treatment options for children with juvenile arthritis in their TMJs.

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.

Stimulus-Responsive Drug Delivery Nanoplatforms for Osteoarthritis Therapy

Osteoarthritis (OA) is one of the most prevalent age-related degenerative diseases. With an increasingly aging global population, greater numbers of OA patients are providing clear economic and societal burdens. Surgical and pharmacological treatments are the most common and conventional therapeutic strategies for OA, but often fall considerably short of desired or optimal outcomes. With the development of stimulus-responsive nanoplatforms has come the potential for improved therapeutic strategies for OA. Enhanced control, longer retention time, higher loading rates, and increased sensitivity are among the potential benefits. This review summarizes the advanced application of stimulus-responsive drug delivery nanoplatforms for OA, categorized by either those that depend on endogenous stimulus (reactive oxygen species, pH, enzyme, and temperature), or those that depend on exogenous stimulus (near-infrared ray, ultrasound, magnetic fields). The opportunities, restrictions, and limitations related to these various drug delivery systems, or their combinations, are discussed in areas such as multi-functionality, image guidance, and multi-stimulus response. The remaining constraints and potential solutions that are represented by the clinical application of stimulus-responsive drug delivery nanoplatforms are finally summarized.

Effects and mechanotransduction pathways of therapeutic ultrasound on healthy and osteoarthritic chondrocytes: a systematic review of in vitro studies

OBJECTIVE

To investigate the effects and mechanotransduction pathways of therapeutic ultrasound on chondrocytes.

METHOD

PubMed, EMBASE and Web of Science databases were searched up to 19^th September 2021 to identify in vitro studies exploring ultrasound to stimulate chondrocytes for osteoarthritis (OA) treatment. Study characteristics, ultrasound parameters, in vitro setup, and mechanotransduction pathways were collected. Risk of bias was judged using the Risk of Bias Assessment for Non-randomized Studies (RoBANS) tool.

RESULTS

Thirty-one studies were included comprising healthy and OA chondrocytes and explants. Most studies had high risk of performance, detection and pseudoreplication bias due to lack of temperature control, setup calibration, inadequate semi-quantitatively analyzes and independent experiments. Ultrasound was applied to the culture plate via acoustic gel, water bath or culture media. Regardless of the setup used, ultrasound stimulated the cartilage production and suppressed its degradation, although the effect size was nonsignificant. Ultrasound inhibited p38, c-Jun N-terminal kinases (JNK) and factor nuclear kappa B (NFκB) pathways in OA chondrocytes to reduce apoptosis, inflammation and matrix degradation, while triggered phosphoinositide-3-kinase/akt (PI3K/Akt), extracellular signal-regulated kinase (ERK), p38 and JNK pathways in healthy chondrocytes to promote matrix synthesis.

CONCLUSION

The included studies suggest that ultrasound application induces therapeutic effects on chondrocytes. However, these results should be interpreted with caution because high risk of performance, detection and pseudoreplication bias were identified. Future studies should explore the application of ultrasound on human OA chondrocytes cultures to potentiate the applicability of ultrasound towards cartilage regeneration of knee with OA.

The therapeutic effects of low-intensity pulsed ultrasound in musculoskeletal soft tissue injuries: Focusing on the molecular mechanism

Musculoskeletal soft tissue injuries are very common and usually occur during both sporting and everyday activities. The intervention of adjuvant therapies to promote tissue regeneration is of great importance to improving people's quality of life and extending their productive lives. Though many studies have focused on the positive results and effectiveness of the LIPUS on soft tissue, the molecular mechanisms standing behind LIPUS effects are much less explored and reported, especially the intracellular signaling pathways. We incorporated all research on LIPUS in soft tissue diseases since 2005 and summarized studies that uncovered the intracellular molecular mechanism. This review will also provide the latest evidence-based research progress in this field and suggest research directions for future experiments.

Transporting Hydrogel via Chinese Acupuncture Needles for Lesion Positioning Therapy

Lesion positioning therapy optimizes medical treatment by directly targeting lesions. However, strong physical barriers greatly hinder its wide use. Here, the Chinese acupuncture needles (CA-needles) with a screw-thread structure at the tip (ST-needle) and the hydrogel with the function of adhesive metal and loaded drug sustained-release structure are designed, through the minimally invasive and precise positioning of lesions by ST-needles, the dry-wet conversion of hydrogel with absorbing fluids and swelling, and the rotation back of ST-needles, the hydrogel is precisely positioned in the subchondral bone with physical barrier to achieve precise positioning therapy for lesions. In vitro experiments show that the ST-needle penetrates the physical barrier of cartilage and enters the subchondral bone. Simultaneously, the hydrogel transfer efficiency of the ST-needle (73.25%) is significantly higher than that of the CA-needle (29.92%) due to the protective effect of the screw-thread structure. In vivo experiments demonstrate that precise positioning in subchondral bone in osteoarthritis rats with ST-needles effectively inhibits abnormal subchondral bone remodeling, alleviating the degeneration and degradation of cartilage. Therefore, ST-needles achieve lesion positioning therapy through minimally invasive penetration of physical barriers, precisely positioning within lesions, and delivering hydrogel to release drugs.

Ultrasound and microbubbles to beat barriers in tumors: Improving delivery of nanomedicine

Successful delivery of drugs and nanomedicine to tumors requires a functional vascular network, extravasation across the capillary wall, penetration through the extracellular matrix, and cellular uptake. Nanomedicine has many merits, but penetration deep into the tumor interstitium remains a challenge. Failure of cancer treatment can be caused by insufficient delivery of the therapeutic agents. After intravenous administration, nanomedicines are often found in off-target organs and the tumor extracellular matrix close to the capillary wall. With circulating microbubbles, ultrasound exposure focused toward the tumor shows great promise in improving the delivery of therapeutic agents. In this review, we address the impact of focused ultrasound and microbubbles to overcome barriers for drug delivery such as perfusion, extravasation, and transport through the extracellular matrix. Furthermore, we discuss the induction of an immune response with ultrasound and delivery of immunotherapeutics. The review discusses mainly preclinical results and ends with a summary of ongoing clinical trials.

The immunoregulatory role of p21 in the development of the temporomandibular joint-osteoarthritis

Objective

We aimed to identify the immunoregulatory role of the cyclin‐dependent kinase inhibitor p21 in the homeostasis of mandibular condylar cartilage affected by mechanical stress.

Materials and methods

Ten C57BL/6 wild‐type (WT) and ten p21^−/− mice aged 8 weeks were divided into the untreated and treated groups. In the treated groups, mechanical stress was applied to the temporomandibular joint (TMJ) through forced mouth opening for 3 hr/day for 7 days. The dissected TMJs were assessed using micro‐CT, histology, and immunohistochemistry.

Results

Treated p21^−/− condyles with mechanical stress revealed more severe subchondral bone destruction, with thinner cartilage layers and smaller proteoglycan area relative to treated WT condyles; untreated WT and p21^−/− condyles had smoother surfaces. Immunohistochemistry revealed significant increases in the numbers of caspase‐3, interleukin‐1β, matrix metalloprotease (MMP)‐9, and MMP‐13 positive cells, and few aggrecan positive cells, in treated p21^−/− than in treated WT samples. Moreover, the number of TUNEL positive cells markedly increased in p21^−/− condyles affected by mechanical stress.

Conclusions

Our findings indicate that p21 in chondrocytes contributes to regulate matrix synthesis via the control ofm aggrecan and MMP‐13 expression under mechanical stress. Thus, p21 might regulate the pathogenesis of osteoarthritis in the TMJ.

Stimulation of oral mucosal regeneration by low intensity pulsed ultrasound: an in vivo study in a porcine model

PURPOSE

Many studies have shown the ability of low intensity pulsed ultrasound (LIPUS) to stimulate the bone, cartilage and tendon regeneration but only a few studied LIPUS interest in the regeneration of the oral mucosa. The purpose of this study is to assess the ability of LIPUS to stimulate the regeneration of the palatal mucosa in a porcine model.

METHODS

Ten adults mini-pigs were used. Two mucosal wounds were realised on the left and right side of the palate of each pig. The right side was treated with LIPUS at 1 MHz of frequency and 300 mW/cm2 of acoustic intensity. The left side was not treated. The morphology of the wound was evaluated using a polymer silicone molding.

RESULTS

The difference between two sides was significant from day 7 with a p value < 0.0001. At day 21, the wound is completely healed on all pigs with LIPUS. The control soft tissue defect exposed a healing of 80%.

CONCLUSIONS

The present study showed that the use of LIPUS on the oral mucosa accelerates the healing of the masticatory mucosa.

Effectiveness of low-intensity pulsed ultrasound on osteoarthritis of the temporomandibular joint: A review

Loading is indispensable for the growth, development, and maintenance of joint tissues, including mandibular condylar cartilage, but excessive loading or reduced host adaptive capacity can considerably damage the temporomandibular joint (TMJ), leading to temporomandibular joint osteoarthritis (TMJ-OA). TMJ-OA, associated with other pathological conditions and aging processes, is a highly degenerative disease affecting the articular cartilage. Many treatment modalities for TMJ-OA have been developed. Traditional clinical treatment includes mainly nonsurgical options, such as occlusal splints. However, non-invasive therapy does not achieve joint tissue repair and regeneration. Growing evidence suggests that low-intensity pulsed ultrasound (LIPUS) accelerates bone fracture healing and regeneration, as well as having extraordinary effects in terms of soft tissue repair and regeneration. The latter have received much attention, and various studies have been performed to evaluate the potential role of LIPUS in tissue regeneration including that applied to articular cartilage. The present article provides an overview of the status of LIPUS stimulation used to prevent the onset and progression of TMJ-OA and enhance the tissue regeneration of mandibular condylar cartilage. The etiology and management of TMJ-OA are explained briefly, animal models of TMJ-OA are described, and the effectiveness of LIPUS on cell metabolism and tissue regeneration in the TMJ is discussed.

Low-intensity pulsed ultrasound regulates proliferation and differentiation of neural stem cells through notch signaling pathway

Low-intensity pulsed ultrasound (LIPUS) is widely used to regulate stem cell proliferation and differentiation. However, the effect of LIPUS stimulation on neural stem cells (NSCs) is not well documented. In this study, we have identified the optimal parameters, and investigated the cellular mechanisms of LIPUS to regulate the proliferation and differentiation of NSCs in vitro. NSCs were obtained and identified by nestin immunostaining. The proliferation of NSCs were measured by using Cell Counting Kit-8 (CCK-8). The expressions of nutritional factors (NTFs) were detected with immunoassay (ELISA). NSCs differentiation were detected by immunofluorescence and immunoblotting analysis. The expression level of proteins involved in the Notch signaling pathway was also measured by immunoblotting assay. Our results showed the intensity of 69.3 mW/cm² (1 MHz, 8 V) was applicable for LIPUS stimulation. ELISA analysis demonstrated that LIPUS treatment promoted the expression of nutritional factors of NSCs in vitro. Immunofluorescence and immunoblotting analyses suggested that the LIPUS not only reduced the astrocyte differentiation, but also stimulated the differentiation to neurons. Additionally, LIPUS stimulation significantly upregulated expression level of Notch1 and Hes1. Results from our study suggest that LIPUS triggers NSCs proliferation and differentiation by modulating the Notch signaling pathway. This study implies LIPUS as a potential and promising therapeutic platform for the optimization of stem cells and enable noninvasive neuromodulation for central nervous system diseases.

Therapeutic Potential Low-Intensity Pulsed Ultrasound for Osteoarthritis: Pre-clinical and Clinical Perspectives

Osteoarthritis (OA), degeneration of cartilage associated with aging, lifestyle, and trauma, is one of the most common diseases that leads to lower quality of life and socioeconomic burden in the United States. Clinically, OA is initially managed by non-steroidal anti-inflammatory drugs, but eventually requires surgical intervention to reduce pain and increase function. Cartilage is a mechanotransductive tissue and requires a mechanical stimulus to sustain its mechanical and physiologic properties. Low-intensity pulsed ultrasound (LIPUS) is a cyclic acoustic wave that can provide essential mechanical stimuli to activate molecular and cellular pathways leading to chondrocyte proliferation, differentiation and activity, as well as to inhibit inflammatory pathways associated with OA. The activation of chondrocyte proliferation and inhibition of anti-inflammatory cytokines make LIPUS a potential therapy for mild to moderate OA. Although a few review articles have described the effects of ultrasound on chondrocytes and cartilage, there remains a need for a comprehensive analysis of our current understanding of the basic science and clinical status of the effects of low-intensity ultrasound on chondrocytes and cartilage and the implications of these studies on LIPUS as a therapeutic option for OA. This review analyzes recent literature describing the results of LIPUS using in vitro and in vivo pre-clinical models and clinical studies, as well as future directions for research.

Low-intensity pulsed ultrasound inhibits VEGFA expression in chondrocytes and protects against cartilage degeneration in experimental osteoarthritis

Low-intensity pulsed ultrasound (LIPUS), a noninvasive physical therapy, was recently demonstrated to be an effective treatment for osteoarthritis (OA). Vascular endothelium growth factor A (VEGFA) has been found to be upregulated in the articular cartilage, synovium and subchondral bone of OA patients, leading to cartilage degeneration, synovitis and osteophyte formation. However, the functions and mechanisms of LIPUS in regulating chondrocyte-derived VEGFA expression are still unclear. In this study, we investigated whether LIPUS attenuated OA progression by (a) decreasing the percentage of VEGFA-positive cells in mouse articular cartilage destabilised through medial meniscus surgery and (b) relieving interleukin-1β-induced VEGFA expression in mouse primary chondrocytes. However, this function was negated by a p38 mitogen-activated protein kinase (p38 MAPK) inhibitor. In addition, we found that LIPUS ameliorated VEGFA-mediated disorders in cartilage extracellular matrix metabolism and chondrocyte hypertrophy during OA development. In conclusion, our data indicate a novel effect of LIPUS in regulating the expression of osteoarthritic chondrocyte-derived VEGFA through the suppression of p38 MAPK activity.

Effects of collimated and focused low-intensity pulsed ultrasound stimulation on the mandible repair in rabbits

Background

This study was to evaluate the effects of low-intensity collimated pulse ultrasound (LICU) and low-intensity focused-pulse ultrasound (LIFU) stimulation on the osteogenesis in the porous silicon carbide (SiC) scaffold implanted in the rabbit mandible.

Methods

Rabbits were randomly divided into LIFU group, LICU group and control group (without ultrasound treatment). The intensities of LICU and LIFU were 30 and 300 mW/cm², respectively. The subcutaneous and subperiosteal temperatures were measured continuously during the 20-min ultrasound treatment. Then, the porous SiC scaffolds were implanted into the mandible, followed by LICU or LIFU once daily, and the quantity and structure of bone were assessed by methylene blue-acid fuchsin staining and micro-CT at 3, 6 and 9 weeks after implantation.

Results

The changes in the subcutaneous and subperiosteal temperatures during LICU and LIFU were less than 1 °C. The bone mass increased and the structure of bone tissues became more mature over time. The bone mass and mean pore occupancy fraction (POF) in the LIFU group were significantly greater than in the LICU group at three time points (P<0.05). Bone ingrowth in different directions was observed, and the new bone formation in the mesial, distal, top, and lingual sides of the implants in the LIFU group was greater than in the LICU group and control group (P<0.05).

Conclusions

LIFU and LICU may effectively promote bone formation in the mandible scaffold, and LIFU significantly accelerates bone formation in both buccal side and lingual side of the scaffold.