Ultrasound Produced by a Conventional Therapeutic Ultrasound Unit Accelerates Fracture Repair

Study on the Effects of Low-Intensity Pulsed Ultrasound and Iron Ions for Proliferation and Differentiation of Osteoblasts

OBJECTIVE

This study involved the proliferation and differentiation of osteoblasts treated with low-intensity pulsed ultrasound (LIPUS) and iron (Fe3+) ions, respectively. The biological effects of LIPUS and Fe3+ ions on the proliferation and differentiation of osteoblasts were also evaluated.

METHODS

MC3T3-E1 cells were seeded in six-well plates with the medium, which contained different concentrations of Fe3+ (0, 100, 200, 300, 400, 500, 600 and 700 μg L-1, respectively). LIPUS treatment was directed at the bottom of the plate for 20 min at an intensity of 80 mW cm-2 every day.

RESULTS

Viability results showed that a dose of 400 μg L-1 Fe3+ ions had the best effect at promoting osteogenic proliferation in cell culture. The results of alkaline phosphatase staining and mineralization indicated that the differentiation of osteoblasts was promoted by LIPUS and Fe3+ ions. Fluorescence staining results showed that the number of cell nuclei in the LIPUS, Fe3+ and LIPUS-Fe groups increased by 37.20%, 55.81% and 89.76%, respectively. Migration data indicated that migration and proliferation rates were increased by LIPUS and Fe3+, and the results of protein expression indicated that LIPUS and Fe3+ may increase the expression of Wnt, β-catenin, and Runx2, hence promoting normal bone regeneration and development.

CONCLUSION

The combination of LIPUS (1.5 MHz, 80 mW cm-2) and Fe3+ accelerates the proliferation and differentiation of osteoblasts significantly compared with single-factor treatment (stimulated by LIPUS and Fe3+ ions, respectively). This study could establish a foundation for LIPUS-responsive biomaterials in the repair and regeneration of bone tissues.

Study on Synergistic Effects of Nanohydroxyapatite/High-Viscosity Carboxymethyl Cellulose Scaffolds Stimulated by LIPUS for Bone Defect Repair of Rats

Despite the self-healing capacity of bone, the regeneration of critical-size bone defects remains a major clinical challenge. In this study, nanohydroxyapatite (nHAP)/high-viscosity carboxymethyl cellulose (hvCMC, 6500 mPa·s) scaffolds and low-intensity pulsed ultrasound (HA-LIPUS) were employed to repair bone defects. First, hvCMC was prepared from ramie fiber, and the degree of substitution (DS), purity, and content of NaCl of hvCMC samples were 0.91, 99.93, and 0.017%, respectively. Besides, toxic metal contents were below the permissible limits for pharmaceutically used materials. Our results demonstrated that the hvCMC is suitable for pharmaceutical use. Second, nHAP and hvCMC were employed to prepare scaffolds by freeze-drying. The results indicated that the scaffolds were porous, and the porosity was 35.63 ± 3.52%. Subsequently, the rats were divided into four groups (n = 8) randomly: normal control (NC), bone defect (BD), bone defect treated with nHAP/hvCMC scaffolds (HA), and bone defect treated with nHAP/hvCMC scaffolds and stimulated by LIPUS (HA-LIPUS). After drilling surgery, nHAP/hvCMC scaffolds were implanted in the defect region of HA and HA-LIPUS rats. Meanwhile, HA-LIPUS rats were treated by LIPUS (1.5 MHz, 80 mW cm-2) irradiation for 2 weeks. Compared with BD rats, the maximum load and bone mineral density of HA-LIPUS rats were increased by 20.85 and 51.97%, respectively. The gene and protein results indicated that nHAP/hvCMC scaffolds and LIPUS promoted the bone defect repair and regeneration of rats significantly by activating Wnt/β-catenin and inhibiting OPG/RANKL signaling pathways. Overall, compared with BD rats, nHAP/hvCMC scaffolds and LIPUS promoted bone defect repair significantly. Furthermore, the research results also indicated that there are synergistic effects for bone defect repair between the nHAP/hvCMC scaffolds and LIPUS.

Low-Intensity Pulsed Ultrasound Maintains Bone Mass After Withdrawal of Human Parathyroid Hormone in Ovariectomized Mice

The intermittent injection of teriparatide, a recombinant fragment of human parathyroid hormone (PTH 1-34), activates anabolic activity on bone turnover. However, the PTH administration period is limited to 2 years. Thus, sequential therapy after discontinuation of PTH is required. Low-intensity pulsed ultrasound (LIPUS) has been widely used for bone fracture healing. In this study, we examined the effects of LIPUS on bone mass after PTH withdrawal in ovariectomized (OVX) model mice. The LIPUS-non-irradiated femoral trabecular bone mineral density (BMD) in the treated after PTH withdrawal was significantly decreased. Meanwhile, the femoral BMD in the OVX + PTH-LIPUS group was remarkably higher than that of the OVX group. Additionally, mRNA expression of Runx2, Osterix, Col1a1, and ALP increased significantly following LIPUS irradiation after PTH withdrawal. These results suggest that LIPUS protected against femoral trabecular BMD loss and up-regulated the osteogenic factors following PTH withdrawal in OVX mice.

Ultrasound-Triggered Amoxicillin Release from Chitosan/Ethylene Glycol Diglycidyl Ether/Amoxicillin Hydrogels Having a Covalently Bonded Network

An antibiotic release system triggered by ultrasound (US) was investigated using chitosan (CS)/ethylene glycol diglycidyl ether (EGDE) hydrogel carriers with amoxicillin (Amox) drug. Different CS concentrations of 1.5, 2, 2.5, and 3 wt % were gelled with EGDE and Amox was entrapped in the hydrogel carrier; the accelerated release was observed as triggered by 43 kHz US exposure at different US output powers ranging from 0 to 35 W. Among these CS hydrogel systems, the degree of accelerated Amox release depended on the CS concentration for the hydrogelation and the matrix with 2 wt % CS exhibited efficient Amox release at 35 W US power with around 19 μg/mL. The drug released with time was fitted with Higuchi and Korsmeyer-Peppas models, and the enhancement was caused by US aiding drug diffusion within the hydrogel matrix by a non-Fickian diffusion mechanism. The US effect on the viscoelasticity of the hydrogel matrix indicated that the matrix became somewhat softened by the US exposure to the dense hydrogels for 2.5 and 3% CS/EGDE, while the degree of softening was slightly marked in the CS/EGDE hydrogels prepared with 1.5 and 2% CS concentration. Such US softening also aided drug diffusion within the hydrogel matrix, suggesting an enhanced Amox release.

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.

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.

Recent advances in the molecular mechanisms of low-intensity pulsed ultrasound against inflammation

Low-intensity pulsed ultrasound (LIPUS), as a safe and potent physical therapy, has been widely used. It has been demonstrated that LIPUS could induce multiple biological effects, such as relieving pain, accelerating tissue repair/regeneration, and alleviating inflammation. A number of in vitro studies have indicated that LIPUS could significantly reduce the expression of proinflammatory cytokines. This anti-inflammatory effect has also been verified in many in vivo researches. However, the molecular mechanisms underlying LIPUS against inflammation are far from fully elucidated and may differ among different tissues and cells. Here, we review the applications of LIPUS against inflammation through different signaling pathways including nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and phosphatidylinositol-3-kinase/serine/threonine kinase (PI3K/Akt), and discuss the underlying mechanisms. The positive effects of LIPUS on exosomes against inflammation and related signaling pathways are also discussed. A systematic overview of recent advances will present a deeper understanding of the molecular mechanisms of LIPUS, thus boosting our ability to optimize this promising anti-inflammatory therapy.

Transcranial low-intensity ultrasound stimulation for treating central nervous system disorders: A promising therapeutic application

Transcranial ultrasound stimulation is a neurostimulation technique that has gradually attracted the attention of researchers, especially as a potential therapy for neurological disorders, because of its high spatial resolution, its good penetration depth, and its non-invasiveness. Ultrasound can be categorized as high-intensity and low-intensity based on the intensity of its acoustic wave. High-intensity ultrasound can be used for thermal ablation by taking advantage of its high-energy characteristics. Low-intensity ultrasound, which produces low energy, can be used as a means to regulate the nervous system. The present review describes the current status of research on low-intensity transcranial ultrasound stimulation (LITUS) in the treatment of neurological disorders, such as epilepsy, essential tremor, depression, Parkinson's disease (PD), and Alzheimer's disease (AD). This review summarizes preclinical and clinical studies using LITUS to treat the aforementioned neurological disorders and discusses their underlying mechanisms.

MRI Bone Abnormality of the Knee following Ultrasound Therapy: Case Report and Short Review

Ultrasound (US) therapy in sports and medical pathologies is widely used by many physiotherapists and sports medicine clinicians; however, data regarding their potential side effects remain rare. We report a case of a 21-year-old woman with iliotibial band (ITB) syndrome treated with a physiotherapy session combined with US therapy. She had twenty 7 min US sessions on the knee, for 3 months (US at 1 Mhz with an intensity between 1 and 2 W/cm²). Due to persistence of the ITB syndrome's symptomatology after the 3 months of physiotherapy sessions, an MRI (magnetic resonance imaging) was carried out and revealed osteonecrosis-like bone abnormalities on the external femoral condyle, the external tibial plateau, and the proximal fibula. In view of these lesions, the ultrasonic therapy was stopped, and a repeat MRI demonstrated the progressive disappearance of these imaging abnormalities one year after the last US (ultrasound) treatment. In light of this case, we propose here a short review of reported osseous "osteonecrosis" abnormalities associated with US therapies.

Harnessing Ultrasound for Targeting Drug Delivery to the Brain and Breaching the Blood–Brain Tumour Barrier

Despite significant advances in developing drugs to treat brain tumours, achieving therapeutic concentrations of the drug at the tumour site remains a major challenge due to the presence of the blood–brain barrier (BBB). Several strategies have evolved to enhance brain delivery of chemotherapeutic agents to treat tumours; however, most approaches have several limitations which hinder their clinical utility. Promising studies indicate that ultrasound can penetrate the skull to target specific brain regions and transiently open the BBB, safely and reversibly, with a high degree of spatial and temporal specificity. In this review, we initially describe the basics of therapeutic ultrasound, then detail ultrasound-based drug delivery strategies to the brain and the mechanisms by which ultrasound can improve brain tumour therapy. We review pre-clinical and clinical findings from ultrasound-mediated BBB opening and drug delivery studies and outline current therapeutic ultrasound devices and technologies designed for this purpose.

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

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

Effect of Low-Intensity Pulsed Ultrasound on the Graft-Bone Healing of Artificial Ligaments: An In Vitro and In Vivo Study

BACKGROUND

As many researchers have focused on promoting the graft-bone healing of artificial ligaments, even with numerous chemical coatings, identifying a biosafe, effective, and immediately usable method is still important clinically.

PURPOSE

(1) To determine whether a low-intensity pulsed ultrasound system (LIPUS) promotes in vitro cell viability and osteogenic differentiation and (2) to assess the applicability and effectiveness of LIPUS in promoting the graft-bone healing of artificial ligaments in vivo.

STUDY DESIGN

Controlled laboratory study.

METHODS

Polyethylene terephthalate (PET) sheets and grafts were randomly assigned to control and LIPUS groups. MC3T3-E1 preosteoblasts were cultured on PET sheets. Cell viability and morphology were evaluated using a live/dead viability assay and scanning electron microscopy. Alkaline phosphatase activity, calcium nodule formation, and Western blot were evaluated for osteogenic differentiation. For in vivo experiments, the effect of LIPUS was evaluated via an extra-articular graft-bone healing model in 48 rabbits: the osteointegration and new bone formation were tested by micro-computed tomography and histological staining, and the graft-bone bonding was tested by biomechanical testing.

RESULTS

Cell viability was significantly higher in the LIPUS group as compared with control (living and dead compared between control and LIPUS groups, P = .0489 vs P = .0489). Better adherence of cells and greater development of extracellular matrix were observed in the LIPUS group. Furthermore, LIPUS promoted alkaline phosphatase activity, calcium nodule formation, and the protein expression of collagen 1 (P = .0002) and osteocalcin (P = .0006) in vitro. Micro-computed tomography revealed higher surrounding bone mass at 4 weeks and newly formed bone mass at 8 weeks in the LIPUS group (P = .0014 and P = .0018). Histological analysis showed a narrower interface and direct graft-bone contact in the LIPUS group; the surrounding bone area at 4 weeks and the mass of newly formed bone at 4 and 8 weeks in the LIPUS group were also significantly higher as compared with control (surrounding bone, P < .0001; newly formed bone, P = .0016 at 4 weeks and P = .005 at 8 weeks). The ultimate failure load in the LIPUS group was significantly higher than in the control group (P < .0001 at 4 weeks; P = .0008 at 8 weeks).

CONCLUSION

LIPUS promoted the viability and osteogenic differentiation of MC3T3-E1 preosteoblasts in vitro and enhanced the graft-bone healing of PET artificial ligament in vivo.

CLINICAL RELEVANCE

LIPUS is an effective physical stimulation to enhance graft-bone healing after artificial ligament implantation.

Application of low-intensity pulsed therapeutic ultrasound on mesenchymal precursors does not affect their cell properties

Ultrasound is considered a safe and non-invasive tool in regenerative medicine and has been used in the clinic for more than twenty years for applications in bone healing after the approval of the Exogen device, also known as low-intensity pulsed ultrasound (LIPUS). Beyond its effects on bone health, LIPUS has also been investigated for wound healing of soft tissues, with positive results for various cell processes including cell proliferation, migration and angiogenesis. As LIPUS has the potential to treat chronic skin wounds, we sought to evaluate the effects produced by a conventional therapeutic ultrasound device at low intensities (also considered LIPUS) on the migration capacity of mouse and human skin mesenchymal precursors (s-MPs). Cells were stimulated for 3 days (20 minutes per day) using a traditional ultrasound device with the following parameters: 100 mW/cm2 with 20% duty cycle and frequency of 3 MHz. At the parameters used, ultrasound failed to affect s-MP proliferation, with no evident changes in morphology or cell groupings, and no changes at the cytoskeletal level. Further, the migration and invasion ability of s-MPs were unaffected by the ultrasound protocol, and no major changes were detected in the gene/protein expression of ROCK1, integrin β1, laminin β1, type I collagen and transforming growth factor β1. Finally, RNA-seq analysis revealed that only 10 genes were differentially expressed after ultrasound stimulation. Among them, 5 encode for small nuclear RNAs and 2 encode for proteins belonging to the nuclear pore complex. Considering the results overall, while the viability of s-MPs was not affected by ultrasound stimulation and no changes were detected in proliferation/migration, RNA-seq analysis would suggest that s-MPs do respond to ultrasound. The use of 100 mW/cm2 intensity or conventional therapeutic ultrasound devices might not be optimal for the stimulation the properties of cell populations. Future studies should investigate the potential application of ultrasound using variations of the tested parameters.

Effect of targeted gold nanoparticles size on acoustic cavitation: An in vitro study on melanoma cells

When a liquid is irradiated with high intensities of ultrasound irradiation, acoustic cavitation occurs. Since cavitation can be fatal to cells, it is utilized to destroy cancer tumors. Considering cavitation onset and bubbles collapse, the required ultrasonic intensity threshold can be significantly decreased in the presence of nanoparticles in a liquid. The effects of gold nanoparticles size on acoustic cavitation were investigated in this in vitro study. For this purpose, ultrasonic waves were used at intensities of 0.5, 1 and 2 W/cm² and frequency of 1 MHz in the presence of F-Cys-GNPs with 15, 23 and 79 nm sizes and different concentrations (0.2, 1 and 5 µg/ml) in order to determine their effects on the viability of melanoma cells. This was performed at different incubation times 12, 24 and 36 h. The viability of melanoma cells decreased at higher concentrations and sizes of F-Cys-GNPs. The lowest viability of melanoma cells was seen in those containing 79, 23, and 15 nm F-Cys-GNPs. This finding could be explained from the concept that the nucleation sites on the surface of GNPs increase with an increase in size of GNPs, which results in an increase in the number of cavitation bubbles. Acoustic cavitation in the presence of gold nanoparticles can be used as a way for improving therapeutic effects on the tumors.

Low-Intensity Pulsed Ultrasound for Early-Stage Lumbar Spondylolysis in Young Athletes

OBJECTIVE

To examine the effect of low-intensity pulsed ultrasound (LIPUS) on early-stage spondylolysis in young athletes.

DESIGN

Case-control study.

SETTING

A single outpatient orthopedic and sports clinic.

PATIENTS

A total of 82 young athletes (80 boys and 2 girls; mean age, 14.8 years; range, 10-18 years) with early-stage lumbar spondylolysis were enrolled in this study. All patients were examined by plain radiography and magnetic resonance imaging.

INTERVENTIONS

Patients received either standard conservative treatment combined with LIPUS (n = 35) or without LIPUS (n = 47), according to the sequence of admission. The standard conservative treatment included thoracolumbosacral brace, sports modification, and therapeutic exercise.

MAIN OUTCOME MEASURES

The time required to return to previous sports activities was analyzed by using Kaplan-Meier methods with the log-rank test.

RESULTS

The baseline parameters of both groups were not significantly different. The median time to return to previous sports activities was 61 days [95% confidence interval (CI): 58-69 days] in the group treated with LIPUS, which was significantly shorter than that of the group treated without LIPUS (167 days, 95% CI: 135-263 days; P < 0.01).

CONCLUSIONS

These results suggest that LIPUS combined with conservative treatment for early-stage lumbar spondylolysis in young athletes could be a useful therapy for quick return to playing sports.

Comparison of effects of LLLT and LIPUS on fracture healing in animal models and patients: A systematic review

The aim of this paper is to study the in vivo potency of low-level laser therapy (LLLT) and low intensity pulsed ultrasound (LIPUS) alone, accompanied by bone grafts, or accompanied by other factors on fracture healing in animal models and patients. In this paper, we aim to systematically review the published scientific literature regarding the use of LLLT and LIPUS to accelerate fracture healing in animal models and patients. We searched the PubMed database for the terms LLLT or LIPUS and/or bone, and fracture. Our analysis also suggests that both LIPUS and LLLT may be beneficial to fracture healing in patients, and that LIPUS is more effective. These finding are of considerable importance in those treatments with a LIPUS, as a laser device may reduce healing time. The most clinically relevant impact of the LIPUS treatment could be a significant reduction in the proportion of patients who go on to develop a nonunion. If it is confirmed that the therapeutic influence is true and reliable, patients will obtain benefits from LIPUS and LLLT. Further clinical trials of high methodological quality are needed in order to determine the optimal role of LIPUS and LLLT in fracture healing in patients.

Treatment of Movement Disorders With Focused Ultrasound

Although the use of ultrasound as a potential therapeutic modality in the brain has been under study for several decades, relatively few neuroscientists or neurologists are familiar with this technology. Stereotactic brain lesioning had been widely used as a treatment for medically refractory patients with essential tremor (ET), Parkinson disease (PD), and dystonia but has been largely replaced by deep brain stimulation (DBS) surgery, with advantages both in safety and efficacy. However, DBS is associated with complications including intracerebral hemorrhage, infection, and hardware malfunction. The occurrence of these complications has spurred interest in less invasive stereotactic brain lesioning methods including magnetic resonance imaging–guided high intensity–focused ultrasound (FUS) surgery. Engineering advances now allow sound waves to be targeted noninvasively through the skull to a brain target. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull, recent Food and Drug Administration approval of unilateral thalamotomy for treatment of ET. Clinical studies of stereotactic FUS for aspects of PD are underway. Moderate intensity, pulsed FUS has also demonstrated the potential to safely open the blood-brain barrier for localized delivery of therapeutics including proteins, genes, and cell-based therapy for PD and related disorders. The goal of this review is to provide basic and clinical neuroscientists with a level of understanding to interact with medical physicists, biomedical engineers, and radiologists to accelerate the application of this powerful technology to brain disease

Focused Ultrasound: An Emerging Therapeutic Modality for Neurologic Disease

Therapeutic ultrasound is only beginning to be applied to neurologic conditions, but the potential of this modality for a wide spectrum of brain applications is high. Engineering advances now allow sound waves to be targeted through the skull to a brain region selected with real time magnetic resonance imaging and thermography, using a commercial array of focused emitters. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull. This has led to the recent Food and Drug Administration approval of focused ultrasound (FUS) thalamotomy for unilateral treatment of essential tremor. Clinical studies of stereotactic FUS for aspects of Parkinson's disease, chronic pain, and refractory psychiatric indications are underway, with promising results. Moderate-intensity FUS has the potential to safely open the blood-brain barrier for localized delivery of therapeutics, while low levels of sonic energy can be used as a form of neuromodulation.

The Effectiveness of Human Parathyroid Hormone and Low-Intensity Pulsed Ultrasound on the Fracture Healing in Osteoporotic Bones

Osteoporotic fracture has become a major public health problem, and until today, the treatments available are not satisfactory. While there is growing evidence to support the individual treatment of parathyroid hormone (PTH) administration and low-intensity pulsed ultrasound (LIPUS) exposure as respectively systemic and local therapies during osteoporotic fracture healing, their effects have not yet been investigated when introduced concurrently. This study aimed to evaluate the effects of combined treatment with PTH (1-34) and LIPUS on fracture healing in ovariectomized (OVX) rats. Thirty-two, 12-week-old female Sprague-Dawley rats were OVX to induce osteoporosis. After 12 weeks, the rats underwent surgery to create bilateral mid-diaphyseal fractures of proximal tibiae. All animals were randomly divided into 4 groups (n = 8 for each): control group as placebo, PTH group, LIPUS group, and combined group. PTH group had PTH administration at a dose of 30 μg/kg/day for 3 days/week for 6 weeks. LIPUS group received ultrasound 5 days/week for 20 min/day for 6 weeks and combined group had both PTH administration and LIPUS exposure for 6 weeks. Fracture healing was observed weekly by anteroposterior radiography and micro-CT. Five weeks after the fracture, the tibia were harvested to permit histological assessments and at week 6, for mechanical property of the fracture callus. Micro-CT showed that the PTH and combined groups exhibited significantly higher BMD and trabecular bone integrity than control group at weeks 4-6. Radiography, fracture healing score and mean callus area indicated that the combined group revealed better healing processes than the individual groups. Mechanically, bending moment to failure was significantly higher in LIPUS, PTH and combined groups than in control group. These data suggest that the combined treatment of PTH and LIPUS have been shown to accelerate fracture bone healing and enhance bone properties rather than single agent therapy, and may be considered as a treatment remedy for fracture healing in postmenopausal osteoporosis.

An Evaluation of the Effect of Therapeutic Ultrasound on Healing of Mandibular Fracture

The mandible is the most frequently fractured bone in maxillofacial trauma, the treatment of which consists of reduction and fixation of dislocated fragments by open or closed approach. Innovative techniques toward reducing the period of the postoperative intermaxillary fixation (IMF) are being researched. A relatively unknown treatment that may have an effect on fracture healing is ultrasound. Recent clinical trials have shown that low-intensity pulsed ultrasound (LIPUS) has a positive effect on bone healing. The aim of this study was to evaluate the effect of LIPUS on healing by its application in fresh, minimally displaced or undisplaced mandibular fracture in young and healthy individuals. A total of 28 healthy patients were selected randomly from the outpatient department needing treatment of mandibular fractures. They were then randomly allocated to either of the following two groups-experimental group and study group. After IMF, patients in experimental group received pulsed ultrasound signals with frequency of 1 MHz, with temporal and spatial intensity of 1.5 W/cm(2), pulsed wave for 5 minutes on every alternate day for 24 days, whereas patients in control group received no therapy except IMF. Radiographic density at the fracture zone was assessed from the radiograph by Emago (Emago, Amsterdam, Netherlands) Image Analysis software before IMF then at 1st to 5th weeks post-IMF. The amount of clinical mobility between fracture fragments was assessed by digital manipulation of fractured fragment with the help of periodontal pocket depth measuring probe in millimeters at pre-IMF and after 3 weeks. Pain was objectively measured using a visual analogue scale at weekly interval. The data collected were subjected to unpaired "t" test. The experimental group showed significant improvement in radiographic density compared with control group at 3- and 5-week interval; pain perception was significantly reduced in experimental group compared with study group in the subsequent weeks. No significant difference was found in clinical mobility between fracture fragments at 3-week interval. The present study provides a basis for application of therapeutic controlled ultrasound as an effective treatment modality to accelerate healing of fresh, minimally displaced mandibular fracture.

Contribuição da aplicação do ultrassom de baixa potência na prevenção de osteopenia em tíbias de ratos sob ausência de carga

Este trabalho objetivou verificar se o ultrassom de baixa potência (US) previne a ocorrência de osteopenia em tíbias de ratos sob ausência de carga. Foram utilizados 45 Rattus novergicus albinus, Wistar adultos, machos, distribuídos em cinco grupos iguais: C - animais-controle livres em gaiolas por 21 dias; S - animais suspensos pela cauda por 21 dias; ST - suspensos pela cauda por 21 dias e concomitantemente tratados com US; S→C - suspensos por 21 dias e depois permanecendo livres em gaiolas por mais 21 dias; S→CT - suspensos por 21 dias e depois permanecendo livres em gaiolas por mais 21 dias e concomitantemente tratados com US. O tratamento foi realizado com US de 1,5MHz, ciclo de trabalho 1:4, 30mW/cm², na tíbia direita, por 15 sessões de 20 minutos cada, cinco sessões por semana. Ainda vivos, os animais foram submetidos a exame de densitometria óssea para verificação da densidade mineral óssea (DMO) e do conteúdo mineral ósseo (CMO). Após a eutanásia dos animais, as tíbias foram desarticuladas, dissecadas e submetidas a ensaio mecânico destrutivo para análise da força máxima (Fmáx) e da rigidez (R). Foram avaliados também o comprimento (L) e o diâmetro (D) no ponto médio da tíbia. O grupo S apresentou valores de DMO, CMO, Fmáx, R, L e D menores em relação ao grupo C, demonstrando que a suspensão pela cauda é prejudicial a estas variáveis. O tratamento dos animais suspensos com o US, grupo ST, elevou os valores de CMO e DMO em relação aos do grupo S, igualando-os aos do grupo C. A Fmáx, R e L do grupo ST aumentou em relação ao grupo S e também em relação ao grupo C (p<0,05). Nenhuma diferença significativa foi encontrada entre as variáveis analisadas para os grupos S→CT e S→C (p>0,05). Os resultados obtidos neste estudo permitem concluir que o US de baixa potência contribuiu na prevenção e reversão da ocorrência da osteopenia nos animais submetidos à suspensão pela cauda, demonstrando que a ausência do estímulo mecânico causada pela impossibilidade da deambulação pode ser minimizada pela ação mecânica deste.

Numerical analysis for transverse microbead trapping using 30 MHz focused ultrasound in ray acoustics regime

We have recently devised a remote acoustic manipulation method with high frequency focused ultrasonic beam of 30-200 MHz, and experimentally realized it by the intensity gradient near the beam's focus. A two-dimensional (or transverse) acoustic trapping was demonstrated by directly applying the acoustic radiation force on lipid spheres and leukemia cells that were individually moved towards the focus. Only longitudinal waves were then considered because both target and propagation media involved were fluid e.g., water or phosphate buffer saline. In order for our current technique to be applicable to bead-based assay approaches using micron-sized polystyrene spheres as in optical tweezers, the possibility of microbead trapping must first be investigated from theoretical perspective. In this paper, a simulation study in the ray acoustics regime (bead diameter D>ultrasonic wavelength λ of trapping beam) is thus undertaken by calculating the acoustic radiation force on a polystyrene bead generated from 30 MHz focused beam of Gaussian intensity profile. Analytical trapping models for a bead located in the near-/far fields and on the focal plane are derived by incorporating both longitudinal- and shear force terms into our existing ray acoustics model for liquid targets. The net radiation force is computed by adding the two terms, and the resultant trapping force is defined as a negative net radiation force in the positive transverse direction (y>0). The magnitude of the trapping force and its spatial range are evaluated in the same direction by varying bead size (D=2 λ=100 μm or 3 λ=150 μm), location, and transducer's f-number (= 1 or 2). When the bead size is increased, all force components exerted on the bead is increased in the near field of ultrasound for both f-numbers. With f-number=1 being used, the peak longitudinal-, shear- , and net forces are -3.1 nN, -9.8 nN, and -12.7 nN for D=2 λ, whereas the forces are increased to -5.3 nN, -21.0 nN, and -25.7 nN for D=3 λ. In case of f-number=2, the peak magnitudes of the forces are 1.2 nN, -7.8 nN, and -6.6 nN for D=2 λ, whereas they are increased to 5.9 nN, -17.1 nN, and -12.0 nN for D=3 λ. With f-number=1, the net trapping forces at (0, y, -2 λ) can be reached to -39.8 nN for D=2 λ and -65.2 nN for D=3 λ, and -7.8 nN for D=2 λ and -15.2 nN for D=3 λ at (0, y, -14 λ). When f-number=2 is used, the peak trapping forces at (0, y, -2 λ) can be -3.4 nN for D=2 λ and -5.9 n N for D=3 λ, while they are -6.3 nN for D=2 λ and -12.0 nN for D=3 λ at (0, y, -14 λ). In the near filed, the bead can be trapped in the range from 0 to 340 μm for D=2 λ, and from 0 to 380 μm for D=3 λ. The trapping range Rtrap with f-number=2 lies from 0 to 295 μm for D=2 λ, and from 0 to 340 μm for D=3 λ. As either a larger bead or a lower f-numbered trapping beam is used, a stronger trapping force can be produced in the region. When a bead is more closely positioned to the focus, the trapping occurs in multiple locations and the net force variation becomes more complicated. In the far field, with f-number=1 being used, the peak longitudinal-, shear- , and net forces are 4.6 nN, 6.8 nN, and 11.4 nN for D=2 λ, whereas the forces are increased to 11.4 nN, 12.1 nN, and 23.6 nN for D=3 λ. In case of f-number=2, the maximum value of each force is 4.4 nN, 1.8 nN, and 5.0 nN for D=2 λ, respectively, whereas it becomes 12.3 nN, -0.7 nN, and 10.6 nN for D=3 λ. The bead is forced to move away from the beam axis by a positive net force for y>0 and a negative net force for y<0. With f-number=1, the peak repulsive forces at (0, y, 5 λ) can be 25.8 nN for D=2 λ and 49.9 nN for D=3 λ, and 3.4 nN for D=2 λ and 7.5 nN for D=3 λ at (0, y, 20 λ). When f-number=2 is used, the forces at (0, y, 5 λ) can be 3.9 nN for D=2 λ and 9.5 nN for D=3 λ, while they are 3.7 nN for D=2 λ and 7.8 nN for D=3 λ at (0, y, 20 λ). As the bead is placed farther away from the focus, the net repulsive force is reduced and yet the bead trapping is difficult throughout the far-field region. On the focal plane, with f-number=1, the peak longitudinal-, shear- , and net trapping forces are 31.8 nN, -36.2 nN, and -16.5 nN for D=2 λ, whereas the forces are changed to 73.9 nN, -58.2 nN, and -42.7 nN for D=3 λ. In case of f-number=2, the peak magnitudes of the forces are 6.4 nN, -7.0 nN, and -1.6 nN for D=2 λ, whereas they are increased to 18.1 nN, -15.8 nN, and -3.9 nN for D=3 λ. The Rtrap ranges from 33 to 131 μm for D=2 λ, and from 52 to 170 μm for D=3 λ when f-number=1. The Rtrap with f-number=2 is then located from 0 to 238 μm for D=2 λ, and from 73 to 288 μm for D=3 λ. Hence, the results suggest that microbeads such as polystyrene spheres may acoustically be controlled as remote handles with focused sound beam for bead-bioassay applications, where trapped beads can be used to induce cellular response change by exerting mechanical stress on single cells.

Stimuli-responsive biodegradable poly(methacrylic acid) based nanocapsules for ultrasound traced and triggered drug delivery system

Ultrasound contrast agents (UCAs) have been investigated for echogenic intravenous drug delivery system. Due to the traditional UCAs with overlarge size (micro-scale), their reluctant accumulation in target organs and the instability have presented severe obstacles to the accurate response to the ultrasound and severely limited their further clinical application. Furthermore, elimination of drug carriers from the biologic system after their carrying out the diagnostic or therapeutic functions is one important aspect to be considered. The drug carriers with large sizes, avoiding renal filtration, will lead to increasing toxicity. In this present paper, we design and develop a new type of triple-stimuli responsive (ultrasound/pH/GSH) biodegradable nanocapsules, in which fill up with perfluorohexane, and the DOX-loaded PMAA with disulfide crosslinking forms the wall. These soft nanocapsules with uniform size of 300 nm can easily enter the tumor tissues via EPR effects. The PMAA shell has high DOX-loading content (36 wt%) and great drug loading efficiency (93.5%), the PFH filled can effectively enhance US imaging signal through acoustic droplet vaporization (ADV), ensuring diagnostic and image-guided therapeutic applications. What is more, the disulfide-crosslinked PMAA shell is biodegradable and thus safe for normal organisms. These merits enabled us optimize the balance of diagnostic, therapeutic and biodegradable functionalities in a multifunctional theranostic nanoplatform.

In vitro methods for evaluating therapeutic ultrasound exposures: present-day models and future innovations

Although preclinical experiments are ultimately required to evaluate new therapeutic ultrasound exposures and devices prior to clinical trials, in vitro experiments can play an important role in the developmental process. A variety of in vitro methods have been developed, where each of these has demonstrated their utility for various test purposes. These include inert tissue-mimicking phantoms, which can incorporate thermocouples or cells and ex vivo tissue. Cell-based methods have also been used, both in monolayer and suspension. More biologically relevant platforms have also shown utility, such as blood clots and collagen gels. Each of these methods possesses characteristics that are well suited for various well-defined investigative goals. None, however, incorporate all the properties of real tissues, which include a 3D environment and live cells that may be maintained long-term post-treatment. This review is intended to provide an overview of the existing application-specific in vitro methods available to therapeutic ultrasound investigators, highlighting their advantages and limitations. Additional reporting is presented on the exciting and emerging field of 3D biological scaffolds, employing methods and materials adapted from tissue engineering. This type of platform holds much promise for achieving more representative conditions of those found in vivo, especially important for the newest sphere of therapeutic applications, based on molecular changes that may be generated in response to non-destructive exposures.

Effects of different therapeutic ultrasound intensities on fracture healing in rats

Low-intensity pulsed ultrasound (LIPUS) with I(SATA)= 30 mW/cm(2) has been proven in facilitating fracture healing, which the spatial average intensity over the on period (I(SATP)) equals 150 mW/cm(2). As active ultrasound wave is only delivered during the on period, we postulate 150 mW/cm(2) is responsible for the beneficial effect of LIPUS. In this study, we compare the biologic effects of 30 mW/cm(2) and 150 mW/cm(2). We propose I(SATA) = 150 mW/cm(2) could further enhance fracture healing process. Closed femoral fractured Sprague-Dawley rats were randomized into control, LIPUS-30 (30 mW/cm(2)) and LIPUS-150 (150 mW/cm(2)) groups. Weekly radiographs and endpoint microCT, histomorphometry, and biomechanical tests were performed. The results show that LIPUS-30 had significantly higher low-density bone volume fraction and woven bone percentage than that of control and LIPUS-150 in microCT and histologic measurements, respectively. Mechanically, failure torque of LIPUS-30 was significantly higher than control and LIPUS-150 at week 6. In conclusion, LIPUS at I(SATA)= 150 mW/cm(2) did not further enhance fracture healing.

Involvement of Ca²⁺ and ATP in enhanced gene delivery by bubble liposomes and ultrasound exposure

Recently, we reported the accelerated gene transfection efficiency of laminin-derived AG73-peptide-labeled polyethylene glycol-modified liposomes (AG73-PEG liposomes) and cell penetrating TAT-peptide labeled PEG liposomes using PEG-modified liposomes, which trap echo-contrast gas, "Bubble liposomes" (BLs), and ultrasound (US) exposure. BLs and US exposure were reported to enhance the endosomal escape of AG73-PEG liposomes, thereby leading to increased gene expression. However, the mechanism behind the effect of BLs and US exposure on endosomes is not well understood. US exposure was reported to induce an influx of calcium ions (Ca²⁺) by enhancing permeability of the cell membrane. Therefore, we examined the effect of Ca²⁺ on the endosomal escape and transfection efficiency of AG73-PEG liposomes, which were previously enhanced by BLs and US exposure. For cells treated with EGTA, the endosomal escape and gene expression of AG73-PEG liposomes were not enhanced by BLs and US exposure. Similarly, transfection efficiency of the AG73-PEG liposomes in ATP-depleted cells was not enhanced. Our results suggest that Ca²⁺ and ATP are necessary for the enhanced endosomal escape and gene expression of AG73-PEG liposomes by BLs and US exposure. These findings may contribute to the development of useful techniques to improve endosomal escape and achieve efficient gene transfection.

Análise comparativa dos efeitos do ultrassom terapêutico e laser de baixa potência sobre a proliferação de células musculares durante a diferenciação celular

INTRODUÇÃO: Existe um grande interesse no estabelecimento de recursos e terapias a serem utilizados na tentativa de proporcionar um processo de reparo muscular de melhor qualidade e menor duração. O ultrassom terapêutico (US) e o laser de baixa potência (LBP) são recursos muito usados na prática clínica, porém são escassas, e por vezes contraditórias, as evidências científicas que determinam com segurança os parâmetros dosimétricos e metodológicos adequados. OBJETIVOS: O objetivo do estudo foi analisar o efeito do US e do LBP sobre a proliferação celular durante a diferenciação de mioblastos C2C12. MATERIAIS E MÉTODOS: Os mioblastos foram cultivados em meio de cultura de Eagle modificado por Dulbecco, contendo 10% de soro fetal bovino (SFB), sendo induzida a diferenciação pela adição de 2% de soro de cavalo durante 96 horas. Posteriormente, as células foram irradiadas com US pulsado a 20%, 3 MHz de frequência (intensidades de 0,2 e 0,5 W/cm², durante cinco minutos) ou submetidas ao tratamento com LBP (potência de saída de 10 mW, densidade de energia de 3 e 5 J/cm², por 20 segundos). A proliferação celular foi avaliada após 24h e 72h utilizando o método de MTT. Foram realizados três experimentos independentes, em cada condição citada e células não irradiadas serviram como controle. RESULTADOS: Os resultados obtidos foram submetidos à análise estatística utilizando a Análise de Variância (ANOVA), teste Dunnet, para verificar diferenças entre o grupo controle (não tratado) e os grupos tratados com US e LBP, adotando significância de p < 0,05. Os resultados evidenciaram que não houve diferença significativa na proliferação celular entre as células musculares submetidas a tratamento com ambos os recursos terapêuticos e as células controle, nos períodos de 24h e 72h após tratamento. Além disso, foi possível verificar que não houve aumento significativo no número de células após o período de 72h quando comparado a 24h, confirmando o processo de diferenciação celular, conforme esperado. CONCLUSÕES: Conclui-se que o US e o LBP, nos parâmetros avaliados, não alteraram a proliferação de mioblastos em processo de diferenciação.

Analysis of ultrasound fields in cell culture wells for in vitro ultrasound therapy experiments

Ultrasound is an established therapy method for bone fracture healing, hyperthermia and the ablation of solid tumors. In this new emerging field, ultrasound is further used for microbubble-enhanced drug delivery, gene therapy, sonoporation and thrombolysis. To study selected therapeutic effects in defined experimental conditions, in vitro setups are designed for cell and tissue therapy. However, in vitro studies often lack reproducibility and the successful transfer to other experimental conditions. This is partly because of the uncertainty of the experimental conditions in vitro. In this paper, the ultrasound wave propagation in the most common in vitro ultrasound therapy setups for cell culture wells is analyzed in simulations and verified by hydrophone measurements. The acoustic parameters of the materials used for culture plates and growth media are determined. The appearance and origin of standing waves and ring interference patterns caused by reflections at interfaces is revealed in simulations and measurements. This causes a local maximal pressure amplitude increase by up to the factor of 5. Minor variations of quantities (e.g., growth medium volume variation of 2.56%) increase or decrease the peak rarefaction pressure at a cell layer by the factor of 2. These pressure variations can affect cell therapy results to a large extent. A sealed cell culture well submersed in a water bath provides the best reproducibility and therefore promises transferable therapy results.

Análise da influência do ultrassom de baixa intensidade na região de reparo ósseo em ratos sob ausência de carga

Há evidências de que o ultrassom (US) de baixa intensidade pode acelerar a regeneração óssea. Este trabalho objetivou verificar a ação do US no defeito ósseo, criado experimentalmente em tíbias de ratos sob ausência de carga. Vinte Rattus novergicus albinus, Wistar adultos, divididos em: G1 (n=10), grupo experimental de 15 dias sem suspensão, e G2 (n=10), grupo experimental de 15 dias suspenso pela cauda, foram submetidos à osteotomia em ambas as tíbias e à aplicação do US, frequência de 1,5 MHz, ciclo de trabalho 1:4, 30 mW/cm², nas tíbias direitas por 12 sessões de 20 minutos. Após o sacrifício, as tíbias foram submetidas à análise da Densidade Mineral Óssea (DMO). Os resultados demonstraram DMO de 0,139±0,018 g/cm² para tíbia tratada; 0,131±0,009 g/cm² para tíbia controle no G1; e no G2 registrou-se 0,120±0,009 g/cm² para tíbia tratada e 0,106±0,017 g/cm² para tíbia controle. Houve diferença significante entre os grupos nos quais o G2 apresentou menor DMO, o que demonstra que a suspensão prejudica a manutenção das propriedades ósseas, e entre as tíbias tratadas e controles do G2, demonstrando que o US acelerou o processo de reparo, concluindo que a impossibilidade do estímulo mecânico causada pela não deambulação em um processo de reparo ósseo pode ser minimizada pela ação do US. No G1, a aplicação do US não teve influência significante no aumento da DMO, talvez pelo fato dos animais já terem estímulo mecânico suficiente à formação óssea.

Mechanical means to improve bone strength: ultrasound and vibration

Not all fractures heal well. One method that has been used to improve fracture healing is low-intensity pulsed ultrasound (LIPUS). LIPUS has been US Food and Drug Administration approved for several years, and some preclinical and clinical evidence indicates that fracture healing can be improved by this technique, which appears to be generally safe. There are several suggested mechanisms of action of LIPUS. Clinical studies generally support its usefulness in accelerating fracture healing. A less-established modality is whole body vibration (WBV), which appears to stimulate bone and muscle growth while suppressing adipogenesis in animal studies. Early studies in humans, including some in children with disabilities, suggest that WBV holds promise as a technique for reducing fracture risk. The exact place of WBV in preventing fracture remains to be established.

Osteoporosis: nonpharmacologic management

Osteoporosis is a chronic disorder of the skeleton causing increased bone fragility and fractures. In the second of our 3-part series, we discuss the beneficial effects of nonpharmacologic agents in the management of osteoporosis. We review the evidence supporting the use of exercise, whole-body vibration, hip protectors, low-intensity pulsed ultrasound, bracing, and vertebral augmentation procedures. The mechanism of action, precautions, and expected outcomes are discussed. Nonpharmacologic management of osteoporosis blends in very well with an overall exercise prescription. The nonpharmacologic interventions discussed are readily available and easy to implement. The use of such techniques demonstrates the important role of the physiatrist in the management of osteoporosis.

The evidence of low-intensity pulsed ultrasound for in vitro, animal and human fracture healing

BACKGROUND

Physical stimulation therapies are currently available to enhance fracture healing.

SOURCES OF DATA

A search of PubMed, Medline, CINAHL, DH data and Embase databases was performed using the keywords 'ultrasound' and 'fracture healing'.

AREAS OF AGREEMENT

The evidence in vitro and animal studies suggests that low-intensity pulsed ultrasound (LIPUS) produces significant osteoinductive effects, accelerating the healing process and improving the bone-bending strength.

AREAS OF CONTROVERSY

The evidence in human trials is controversial in fresh, stress fractures and in limb lengthening. LIPUS is effective in delayed unions, in smokers and in diabetic population.

GROWING POINTS

LIPUS is an alternative, less invasive form of treatment for complicated fractures, in patients with poor bone healing and may play a role in the management of large-scale bone defects producing substantial cost savings and decreasing associated disability.

AREAS TIMELY FOR DEVELOPING RESEARCH

There is heterogeneity among in vitro, animal studies and their application to human studies. Further randomized controlled trials of high methodological quality are needed.

Efeitos do ultra-som terapêutico contínuo sobre a proliferação e viabilidade de células musculares C2C12

O ultra-som terapêutico (US) é um recurso bioestimulante utilizado para propiciar reparo muscular de melhor qualidade e menor duração, mas o potencial terapêutico do US contínuo não está totalmente estabelecido. O objetivo deste trabalho foi avaliar o efeito do US contínuo sobre a proliferação e viabilidade de células musculares precursoras (mioblastos C2C12). Mioblastos C2C12 foram cultivados em meio de cultura contendo 10% de soro fetal bovino e irradiados com US contínuo nas freqüências de 1 e 3 MHz nas intensidades de 0,2 e 0,5 W/cm2, durante 2 e 5 minutos. A viabilidade e proliferação celular foram avaliadas após 24, 48 e 72 h de incubação. Grupos não-irradiados serviram como controle. Foram realizados experimentos independentes em cada condição acima, e os dados obtidos submetidos à análise estatística. Os resultados mostram que não houve diferença estatisticamente significativa na proliferação e viabilidade celular entre os mioblastos tratados com US e as culturas controles após os diferentes períodos de incubação, em todos os parâmetros avaliados. Conclui-se que o US contínuo, nos parâmetros avaliados, não foi capaz de alterar a proliferação e viabilidade dos mioblastos.

Effects of therapeutic pulsed ultrasound and dimethylsulfoxide (DMSO) phonophoresis on parameters of oxidative stress in traumatized muscle

Many studies have demonstrated an increase in reactive oxygen species (ROS) and oxidative damage markers after muscle damage. Phonophoresis aims to achieve therapeutically relevant concentrations of the transdermally introduced drug in the tissues subjected to the procedure by the use ultrasound waves. The aim of the study was to evaluate the effects on the therapeutic pulsed ultrasound (TPU) together with gel-dimethylsulfoxide (DMSO) in the parameters of muscular damage and oxidative stress. Male Wistar rats were divided randomly into six groups (n=6): sham (uninjured muscle); muscle injury without treatment; muscle injury and treatment with gel-saline (0.9%); muscle injury and treatment with gel-DMSO (15mg/kg); muscle injury and TPU plus gel-saline; and muscle injury and TPU plus gel-DMSO. Gastrocnemius injury was induced by a single impact blunt trauma. TPU (6min duration, frequency of 1.0MHz, intensity of 0.8W/cm(2)) was used 2, 12, 24, 48, 72, 96 and 120h after muscle trauma. The CK and acid phosphatase activity in serum was used as an indicator of skeletal muscle injury. Superoxide anion, TBARS, protein carbonyls, superoxide dismutase (SOD) and catalase (CAT) activity was used as indicators of stress oxidative. Results showed that TPU and gel-DMSO improved muscle healing. Moreover, superoxide anion production, TBARS level and protein carbonyls levels, superoxide dismutase (SOD) and catalase (CAT) activity were all decreased in the group TPU plus gel-DMSO. Our results show that DMSO is effective in the reduction of the muscular lesion and in the oxidative stress after mechanical trauma only when used with TPU. (E-mail: silveira_paulo2004@yahoo.com.br).

Recombinant human parathyroid hormone (PTH 1-34) and low-intensity pulsed ultrasound have contrasting additive effects during fracture healing

Fracture healing is thought to be naturally optimized; however, recent evidence indicates that it may be manipulated to occur at a faster rate. This has implications for the duration of morbidity associated with bone injuries. Two interventions found to accelerate fracture healing processes are recombinant human parathyroid hormone [1-34] (PTH) and low-intensity pulsed ultrasound (LIPUS). This study aimed to investigate the individual and combined effects of PTH and LIPUS on fracture healing. Bilateral midshaft femur fractures were created in Sprague-Dawley rats, and the animals treated 7 days/week with PTH (10 microg/kg) or a vehicle solution. Each animal also had one fracture treated for 20 min/day with active-LIPUS (spatial-averaged, temporal-averaged intensity [I(SATA)]=100 mW/cm(2)) and the contralateral fracture treated with inactive-LIPUS (placebo). Femurs were harvested 35 days following injury to permit micro-computed tomography, mechanical property and histological assessments of the fracture calluses. There were no interactions between PTH and LIPUS indicating that their effects were additive rather than synergistic. These additive effects were contrasting with LIPUS primarily increasing total callus volume (TV) without influencing bone mineral content (BMC), and PTH having the opposite effect of increasing BMC without influencing TV. As a consequence of the effect of LIPUS on TV but not BMC, it decreased volumetric bone mineral density (vBMD) resulting in a less mature callus. The decreased maturity and persistence of cartilage at the fracture site when harvested offset any beneficial mechanical effects of the increased callus size with LIPUS. In contrast, the effect of PTH on callus BMC but not TV resulted in increased callus vBMD and a more mature callus. This resulted in PTH increasing fracture site mechanical strength and stiffness. These data suggest that PTH may have utility in the treatment of acute bone fractures, whereas LIPUS at an I(SATA) of 100 mW/cm(2) does not appear to be indicated in the management of closed, diaphyseal fractures.

Low-dose X-irradiation promotes mineralization of fracture callus in a rat model

OBJECTIVES

This study investigated the hypothesized beneficial effect of low-dose irradiation (LDI) on fracture callus mineralization in a rat model.

METHODS

Seventy-two male Sprague-Dawley rats were averagely randomized into LDI group (rats treated with LDI) and SHAM group (rats treated with sham irradiation). Right after either LDI or sham irradiation, a standardized closed fracture on the right femur was established. At 2, 3 and 4 weeks postfracture, 12 rats in each group were euthanized. Fracture callus was assessed by using radiography and MicroCT for callus bridging, peripheral quantitative computed tomography (pQCT) for quantifying bone mineral content (BMC) and cross sectional area (CSA), confocal laser scanning microscopy for measuring area fraction of fluorescence labeling (AFFL) and four-point bending test for examining mechanical properties.

RESULTS

The CSA and AFFL were found to be 22 and 33% smaller in the LDI group compared to the SHAM group at 2 weeks (P<0.05 for both), whereas the BMC and AFFL were 15 and 34% higher in the LDI group at 3 weeks (P<0.05 for both). The changing patterns were consistent with the findings in 3-D MicroCT reconstructions. The mechanical parameters (Max-Load, Stiffness and Energy) were also 18, 30 and 24% higher in the LDI group than in the SHAM group at 3 weeks (P<0.05 for all). At 4 weeks, there was no difference found for all assessments between the two groups.

CONCLUSION

The results indicated LDI promoted mineralization at the stage of hard callus formation in a rat fracture model.

Osteogenic effects of low-intensity pulsed ultrasound, extracorporeal shockwaves and their combination - an in vitro comparative study on human periosteal cells

Our previous studies have shown that on human periosteal cells, low-intensity pulsed ultrasound (LIPUS) has an immediate stimulatory effect whereas extracorporeal shockwaves (ESW) have an delayed stimulatory effect. Therefore, we hypothesized that a combined ESW and LIPUS treatment might provide additive or synergistic effects on periosteal cells, by using ESW to trigger a biological activity while using LIPUS to maintain the stimulated activity. Human periosteal cells were subjected to a single session of ESW treatment on day 0 and/or daily LIPUS treatments or no treatment (control). The cell viability, proliferation, and alkaline phosphatase activity on day 6 and day 18 as well as matrix mineralization on day 35 were measured. Results revealed that LIPUS alone had early positive effects on the activities on day 6 only. In contrast, ESW alone had an early destructive effect but exerted delayed stimulatory effects on the cellular activities on day 18. The combined treatment of ESW plus LIPUS produced effects that were comparable to the ESW treatment alone. Although these findings suggest that ESW and LIPUS stimulate the periosteal cells in two different ways and at different times, their additive or synergistic effects could not be proven.

Ultrasound in contemporary physiotherapy practice

The use of therapeutic ultrasound as an element of physiotherapy practice is well established, but the nature of that practice has changed significantly over the last 20 years. This paper aims to review the rationale and range of applications for which this modality is employed in current practice. Whereas in the past, its primary use was as a thermal modality, it is argued that currently, it is the 'non-thermal' aspects of the intervention that are most commonly employed. The predominant use of therapeutic ultrasound is in relation to tissue repair and soft tissue lesion management, where the evidence would support its application in the inflammatory, proliferative and remodelling phases. The clinical outcomes appear to be dose dependent, and whilst this paper does not detail dose related clinical decision making, the broad issues are considered. The future possibilities for the use of the modality are reviewed, and although outside the immediate remit of this paper, the use of therapeutic ultrasound in fracture management is briefly considered.

Ultrasound mediated delivery of drugs and genes to solid tumors

It has long been shown that therapeutic ultrasound can be used effectively to ablate solid tumors, and a variety of cancers are presently being treated in the clinic using these types of ultrasound exposures. There is, however, an ever-increasing body of preclinical literature that demonstrates how ultrasound energy can also be used non-destructively for increasing the efficacy of drugs and genes for improving cancer treatment. In this review, a summary of the most important ultrasound mechanisms will be given with a detailed description of how each one can be employed for a variety of applications. This includes the manner by which acoustic energy deposition can be used to create changes in tissue permeability for enhancing the delivery of conventional agents, as well as for deploying and activating drugs and genes via specially tailored vehicles and formulations.

Fracture repair with ultrasound: clinical and cell-based evaluation

Fracture repair continues to be widely investigated, both within the clinical realm and at the fundamental research level, in part due to the fact that 5% to 10% of fractures result in either delayed union or nonunion, depending on the duration of incomplete healing. Beyond the temporal delay in repair, nonunions share the same unifying characteristic: all periosteal and endosteal repair processes have stopped and the fracture will not heal without surgical intervention. A less-invasive alternative method--low-intensity pulsed ultrasound--has shown promise as a treatment for delayed unions and nonunions and as a method to facilitate distraction osteogenesis. In this paper, we summarize the clinical effectiveness of low-intensity pulsed ultrasound with regard to fracture repair, treatment of nonunion, and distraction osteogenesis and we discuss the results of a multitude of published studies that have sought to elucidate the mechanisms behind that effectiveness through research on low-intensity pulsed ultrasound exposure on osteoblasts and osteoblast precursors. When evaluated clinically, low-intensity pulsed ultrasound was shown to enhance bone repair (most commonly noted as a decrease in healing time), although variations in patient population hindered a definitive claim to clinical effectiveness. In vitro cellular evaluation and in vivo studies on animal models have revealed an increase in cell proliferation, protein synthesis, collagen synthesis, membrane permeability, integrin expression, and increased cytosolic Ca(2+) levels as well as other increased indicators of bone repair in response to low-intensity pulsed ultrasound exposure. Many of the cellular responses to low-intensity pulsed ultrasound mirror the cellular responses to fluid-induced shear flow, suggesting a link between the two as one potential mechanism of action. The considerable amount of information that has been revealed about the behavior of osteoblasts under low-intensity pulsed ultrasound exposure suggests that the exact mechanism of action is complex. It is clear, however, that considerable progress is being made toward uncovering these mechanisms, which has served to encourage the use of low-intensity pulsed ultrasound in new applications. It is posited that successful noninvasive treatment strategies such as low-intensity pulsed ultrasound may be combined with other conventional and novel tissue-regeneration strategies to develop new treatments for large-scale bone defects.