Low-intensity Pulsed Ultrasound Irradiation Research Articles

Effect of Low-Intensity Pulsed Ultrasound on the Expression of Calcium Ion Transport-Related Proteins during Tertiary Dentin Formation

Low-intensity pulsed ultrasound (LIPUS) is known for its positive effect on bone healing and reparative regeneration. This study investigated whether LIPUS affects reparative progression of the tooth and the expression of calcium ion transport-related proteins in odontoblasts and dental pulp cells using a rat dentin–pulp complex injury model. Forty male adult Sprague-Dawley rats underwent cavity preparation in the right maxillary first molar: 20 received LIPUS irradiation on the cavity-prepared tooth; 20 received LIPUS irradiation on the left maxillary first molar. Rats were randomly allocated into four groups: blank control group, LIPUS group, cavity-prepared group, cavity-prepared + LIPUS group. LIPUS irradiation (frequency: 1.5 MHz, 200-µs pulse width, 1-kHz pulse repetition frequency, 30 mW/cm2 spatial averaged temporal averaged intensity) was administered individually for 20 min daily. Rats were sacrificed 1, 3, 7 and 14 d post-operation. The histopathological and cellular morphologic changes in the dentin–pulp complex were detected with hematoxylin and eosin staining. Expression of calcium ion transport-related proteins (Cav1.2, NCX1 and TRPV1) was determined with immunohistochemical staining and imaging analysis. Histopathological analysis revealed obvious reparative dentin formation at day 14 in the cavity-prepared + LIPUS group compared with the other groups. Expression levels of Cav1.2, NCX1 and TRPV1 increased significantly by 22%, 53% and 23%, respectively, at day 1 and increased significantly by 23%, 27% and 22%, respectively, at day 3 in the cavity-prepared + LIPUS group (p < 0.05) compared with the cavity-prepared group. LIPUS has a positive effect on the expression of calcium transport-related proteins during early-stage dentin injury and facilitates tertiary dentin formation; the mechanism for this likely relates to the inflammatory reaction and a mechanical effect.

Effect of low intensity pulsed ultrasound on expression of TGF-β1 and Smads during dentin injury and repair

To explore the effect of low intensity pulsed ultrasound (LIPUS) on TGF-β1/Smad 2, 3 signal pathway during the dentin injury and repair. Methods: Among 25 Sprague-Dawley rats, 5 rats served as a blank control group without treatment. The remaining 20 rats received modified caries preparation inbilateral maxillary first molars to establish a model of dentin-pulp injury and repair. The right maxillary first molars served as a LIPUS group, which received LIPUS irradiation (frequency: 1.5 MHz, pulse width: 200 μs, pulse repetition frequency: 1 kHz, spatial averaged temporal averaged intensity: 30 mW/cm2, 20 min/d), and the left maxillary first molars served as a cavity-prepared group, which received fake LIPUS irradiation. The rats were sacrificed at 1, 3, 5, 7 and 14 days after LIPUS irradiation. Immunohistochemical staining and Image-pro plus 6.0 were applied to detect the expression and distribution of transforming growth factor-beta1 (TGF-β1) and small mothers against decapentaplegic 2/3(Smad 2 and Smad 3). Results: Immunohistochemical staining showed that the expression of TGF-β1 and Smad 2, 3 were low innormal pulp, but they were increased in different degree after dentin injury. The result of image analysis showed that the expression of TGF-β1 in the cavity-prepared group gradually increased at the first day and peaked at day 5, and then it returned to normal level at day 14. However, the expression of TGF-β1 in the LIPUS group were significantly higher than that in the cavity-prepared group at day 3 and 5 (both P<0.05). The expressions of Smad 2,3 in both the LIPUS group and the cavity-prepared group were consistently increased all the way, but the expressions in the LIPUS group were higher compared with that in the cavity-prepared group (P<0.05). Conclusion: The TGF-β1/Smad 2, 3 signal pathway can be activated during the dentin injury and repair. LIPUS can up-regulate the expression of TGF-β1 and Smad 2, 3 in the early period, which may take part in the dentin-pulp complex injury and repair process.

A preliminary study of effects of low-intensity pulsed ultrasound (LIPUS) irradiation on dentoalveolar ankylosis.

The purpose of this experiment was to investigate whether low-intensity pulsed ultrasound (LIPUS) irradiation can inhibit dentoalveolar ankylosis in transplanted rat teeth. LIPUS irradiation (the pulsed ultrasound signal had a frequency of 3.0 MHz, a spatial average intensity of 30 mW/cm2, and a pulse ratio of 1:4) was performed on the face over the re-planted teeth of rats for 4 weeks. After the rats were euthanized, we measured mobility (Periotest value [PTV]) of the transplanted and control teeth using a Periotest. Finally, we performed histological evaluation to detect ankylosis. PTVs tended to be significantly lower for re-planted teeth than for control teeth. Histological evaluation revealed that the roots of all re-planted teeth were coalescent with alveolar bone. Furthermore, no ankylosis was observed in three-fifths of the re-planted teeth following LIPUS irradiation. These results indicate the potential efficacy of LIPUS to inhibit dentoalveolar ankylosis.

Effect of low-intensity pulsed ultrasound therapy on a rat knee joint contracture model.

[Purpose] Histopathological investigation of the effects of low-intensity pulsed ultrasound (LIPUS) on joint components using a rat knee joint contracture model. [Subjects and Methods] Nineteen, 9-week-old Wistar male rats were divided into a control group (n=6) and an experimental group. Rats in the experimental group underwent cast immobilization of the right rear limb for 8 weeks. They were then randomly divided into a non-treatment group (n=6), which was raised under normal conditions for 4 weeks, and a treatment group (n=7), which underwent LIPUS for 4 weeks. LIPUS irradiation was performed at a frequency of 3 MHz, an intensity of 30 mW/cm2, and a pulse rate of 20% duty cycle. Irradiation was performed once daily for 10 min, 5 days per week. At the end of this period, tissue specimens in which the knee sagittal plane could be observed were prepared and observed using an optical microscope. [Results] The extension-limiting angle of the knee joint was significantly less in the treatment group compared with the non-treatment group. The posterior joint capsule was significantly thicker only in the non-treatment group, and the density was 53.5 ± 7.5% for the control group, 77.2 ± 5.7% for the non-treatment group, and 69.2 ± 2.9% for the treatment group, with significant differences existing across all groups. [Conclusion] LIPUS may widen the space between collagen fiber bundles of the joint capsule, thereby improving the range of motion.

Effect of Low-Intensity Pulsed Ultrasound after Mesenchymal Stromal Cell Injection to Treat Osteochondral Defects: An In Vivo Study

We investigated the effect of low-intensity pulsed ultrasound (LIPUS) treatment combined with mesenchymal stromal cell (MSC) injection for cartilage repair and subchondral bone reconstitution for treatment of osteochondral defects. An osteochondral defect was created on both femur grooves of Wistar rats. Four weeks later, bone marrow MSCs were injected into the right knee joint. The rats were divided into two intervention groups: without or with LIPUS irradiation. Cartilage repair was evaluated histologically based on the Wakitani cartilage repair score. Subchondral bone reconstitution was evaluated as bone volume (BV)/tissue volume (TV) by micro-computed tomography analysis. MSC injection improved the cartilage repair score, and LIPUS irradiation improved BV/TV. Combination treatment promoted both cartilage repair and BV/TV improvement. Thus, MSC injection combined with LIPUS irradiation is more effective than either treatment alone in promoting concurrent cartilage repair and subchondral reconstitution.

Histological evaluation of low-intensity pulsed ultrasound on osteochondritis dissecans of the humeral capitellum

BackgroundThe clinical use of low-intensity pulsed ultrasound (LIPUS) was recently evaluated in cases of osteochondritis dissecans of the humeral capitellum (elbow OCD). However, the mechanism underlying the effect of LIPUS in elbow OCD is not well understood. The aim of this study was to histopathologically evaluate the effect of LIPUS irradiation on elbow OCD. MethodsFifteen patients with elbow OCD were enrolled in this study. All patients were juvenile baseball players (average age, 13.1 years). LIPUS was performed under the same conditions as the fracture treatment for an average length of 15.1 days in the preoperative period in seven patients (LIPUS group). Cylindrical tissue specimens obtained at the time of surgery were stained with hematoxylin and eosin and alcian blue, and were also immunostained to detect type 1 collagen (Col-1), osteopontin (OPN), and Runx2. The state of the cartilage and subchondral bone and expression levels of Col-1, OPN, and Runx2 were evaluated with a semiquantitative grading system by a blinded pathologist. Histological and immunohistological findings in both groups were compared using Fisher’s exact test. ResultsBoth groups showed reparative tissue and cartilaginous metaplasia at the separation level near the subchondral bone; Col-1 was expressed in the reparative tissue. Furthermore, OPN and Runx2 were expressed in the interstitial cells near the separation level. The cartilage and subchondral bone findings in histological evaluations did not differ significantly between the LIPUS and control groups. The distribution of OPN expression levels in the two groups was as follows: Grade 0—LIPUS group, zero patients, and control group, five patients; Grade 1—LIPUS group and control group, two patients each; Grade 2—LIPUS group, five patients and control group, one patient; Grade 3—LIPUS group, one patient and control group, zero patients. OPN expression was significantly higher in the LIPUS group than in the control group (p = 0.04). ConclusionLIPUS stimulation increased the expression levels of OPN in elbow OCD.

Effect of Low-Intensity Pulsed Ultrasound on Bone-Healing Process in Murine Low-Turnover Osteoporosis Model

The effects of postmenopausal osteoporosis for bone defect healing processes have already been reported, but not for senile osteoporosis caused by low-turnover metabolism. Low-Intensity-Pulsed Ultrasound (LIPUS) is known to promote bone defect healing in high-turnover osteoporosis an animal model. The aim of this study was to investigate the effect of LIPUS on the bone-healing process in a low-turnover osteoporosis model using the Senescence-Accelerated Mouse Prone 6 (SAMP6) strain of mice. Twenty-week-old SAMP6 and Senescence-Accelerated Mouse Resistant (SAMR1) mice were used as senile osteoporosis and normal aging models, respectively. Bone defects (diameter, 0.9 mm) were created in the both SAMP6 and SAMR1 femurs. At 7days after surgery, the LIPUS irradiation groups of SAMR1 (R1LG) and SAMP6 (P6LG) were exposed to LIPUS (1.0 MHz, 320 mW, 15 min/day) for 6 days. The non-irradiation groups of SAMR1 (R1CG) and SAMP6 (P6CG) were used as controls. All groups were sacrificed at 14 days after creation of bone defects. Radiological analysis, histological evaluation and immunohistochemical staining for osteocalcin (OC) were performed. From the radiological evaluation, the new bone of defected area in SAMR1 group showed cortical bone-like structure, but that in the SAMP6 group showed trabecular bone-like structures. The increase in bone area in P6LG was greater than that in P6CG according to chronological change analysis using X-ray micro-CT (p < 0.01). Histological analysis revealed outward new bone formation originating in the periosteum in P6LG. Positive reaction for OC was localized on the surface of new bone in P6CG, whereas that in P6LG was observed over the whole region of new bone, from the outer to the bone marrow side. These results showed that LIPUS accelerates healing on low-turnover osteoporosis by promoting bone formation from periosteum and supplementing reduced bone formation from bone marrow.

Os efeitos do ultra-som terapêutico nas lesões por esmagamento do nervo ciático de ratos: análise funcional da marcha

Background: The effects of therapeutic ultrasound irradiation on peripheral nerve regeneration are not well known, particularly regarding functional recovery. However, in rats, footprint evaluation is a well-systematized method for measuring the Sciatic Functional Index (SFI), showing close correlation with morphological regeneration of damaged sciatic nerves. Objective: To analyze the influence of therapeutic ultrasound on sciatic nerve regeneration in rats subjected to controlled crushing. Method: 20 Wistar rats (mean body weight: 300 g) were divided into two experimental groups: 1) crushing only (n=10); 2) crushing followed by ultrasound irradiation (n=10). Under general anesthesia, a 5-mm segment of sciatic nerve proximal to its bifurcation in the right thigh was exposed and crushed with constant loading of 15 kg for 10 minutes, using a specially-built device. Low-intensity pulsed ultrasound irradiation (1:5, 0.4 W/cm2, 1 MHz, 2 minutes) was started on the first postoperative day and administered for ten consecutive days. Footprints were obtained weekly (postoperative weeks 13) using a specially-designed walkway, and evaluated using specifically-developed software, according to a previously-tested method, with automatic SFI calculation. Results: The SFI progressively increased in both groups: Group 2, from 101 in the first week to 59.21 (second) and 26.68 (third), i.e. 73% improvement overall; Group 1, from 98.2 (first) to 79.5 (second) and 44 (third), i.e. 55% improvement overall. The differences between the groups were significant for the second and third weeks (p=0.02 and p=0.002, respectively). Conclusion: Low-intensity therapeutic ultrasound accelerates the regeneration of crushed sciatic nerves in rats, as demonstrated by its functional recovery.