Effects of low-level laser therapy on inflammatory symptoms in an arthritis rat model

[Purpose] This study evaluated the effect of low-level laser therapy on inflammatory signs in an arthritis rat model as a foundation for elucidating the mechanism of the anti-inflammatory effect. [Materials and Methods] Eigteen Wistar rats were divided into three groups: group I (arthritis without low-level laser therapy), group II (arthritis with low-level laser therapy), and the control group (sham arthritis control). Arthritis was induced in the right knee by injecting a mixture of kaolin and carrageenan. Low-level laser therapy was continued for seven days after the onset of arthritis by 60 times of repeated irradiation for 10 seconds in the right knee joint area. The joint transverse diameter, pressure pain threshold in the affected knee joint, and mechanical paw withdrawal threshold at the distant site were evaluated the day before the injection and one, three, and seven days after the injection. Pathological changes were observed. [Results] Group II showed better improvement in swelling and pain in the affected knee joint and secondary hyperalgesia at the distance site when compared to group I. In group II, there was only mild infiltration of synovial cells, and the progression of arthritis was suppressed compared with that of group I. [Conclusion] Low-level laser therapy can mitigate swelling and inflammatory pain in the affected knee joint and prevent secondary hyperalgesia.     

Effects of pulse frequency of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells

OBJECTIVE: The purpose of this study was to determine the effect of pulse frequencies of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells in vitro. BACKGROUND DATA: Various photo-biostimulatory effects of LLLT, including bone formation, were affected by some irradiation factors such as total energy dose, irradiation phase, laser spectrum, and power density. However, the effects of pulse frequencies used during laser irradiation on bone formation have not been elucidated. MATERIALS AND METHODS: Osteoblast-like cells isolated from fetal rat calvariae were irradiated once with a low-energy Ga-Al-As laser (830 nm, 500 mW, 0.48-3.84 J/cm2) in four different irradiation modes: continuous irradiation (CI), and 1-, 2-, and 8-Hz pulsed irradiation (PI-1, PI-2, PI-8). We then investigated the effects on cellular proliferation, bone nodule formation, alkaline phosphatase (ALP) activity, and ALP gene expression. RESULTS: Laser irradiation in all four groups significantly stimulated cellular proliferation, bone nodule formation, ALP activity, and ALP gene expression, as compared with the non-irradiation group. Notably, PI-1 and -2 irradiation markedly stimulated these factors, when compared with the CI and PI-8 groups, and PI-2 irradiation was the best approach for bone nodule formation in the present experimental conditions. CONCLUSION: Since low-frequency pulsed laser irradiation significantly stimulates bone formation in vitro, it is most likely that the pulse frequency of LLLT an important factor affecting biological responses in bone formation.     

Effect of low-level laser radiation on some rheological factors in human blood: an in vitro study

OBJECTIVE: The purpose of this study was to investigate the in vitro effects of low-level laser radiation (LLLR) on some rheological factors of the human blood, such as complete blood count (CBC) parameters and blood sedimentation rate (BSR). We were mainly concerned with the alterations caused by LLLR action on blood cells (erythrocytes and leukocytes) of fresh blood obtained from apparently healthy adult patients. We used low doses ranging between 0.80 J x cm(-3) and 4.40 J x cm(-3), at the very low-power densities of the laser radiation, so as not to damage the cell structure and not to alter in an undesired manner their functions. METHODS: Blood samples were taken from 22 volunteers. Where health problems existed, they were indicated for each case. The parameters mentioned above were measured before (control samples) and after irradiation. A He-Ne laser, operating in continuous wave, as a radiation source (632.8 nm, 1 mW, intensity of 8 x 10(-2) W x sr(-1), mean power density incident on blood samples around 30 mW x cm(-2), beam spot diameter 2 mm) was used. The measurements were performed immediately after irradiation. Only the erythrocyte complex was irradiated. EDTA anticoagulant was used. RESULTS: The measurements using a computerized hemoanalyzer type SERONO showed significant differences between control and irradiated blood samples concerning the following parameters: RBC (in 22% of cases), HGB (47.3%), HCT (84.2%), RDW (11%), PLT (5.26%), MPV (33.3%), WBC (5.26%), MONO (26.3%), and GRAN (63.15%). In the case of BSR (44%), the significant differences were noticed especially in the cases of patients suffering from some acute or chronic diseases. Nonsignificant differences were noticed in the cases of MCV, MCH, MCHC, RDW, and LYMPH. CONCLUSIONS: This study has shown that LLLR, even though used at low doses and low power densities, produced some changes of the rheological factors of the blood, as follows: a revitalizing and regenerating effect on mitosis stimulation and a nondamaging and biostimulating effect on the cell membrane (by keeping unmodified MCV, MCH, and MCHC). In 3 cases out of 22, hemolysis (complete or partially) occurred, but we are not yet sure whether this was caused by laser exposure or by certain environmental physical factors.     

Initial effects of low-level laser therapy on growth and differentiation of human osteoblast-like cells

Low-level laser therapy is a clinically well established tool for enhancement of wound healing. In vitro studies have also shown that low level laser therapy has a biostimulatory effect on cells of different origin. The aim of this in vitro study was to investigate the initial effect of low-level laser therapy on growth and differentiation of human osteoblast-like cells. SaOS-2 cells were irradiated with laser doses of 1 J/cm2 and 2 J/cm2 using a diode laser with 670 nm wave length and an output power of 400 mW. Untreated cells were used as controls. At 24 h, 48 h and 72 h post irradiation, cells were collected and assayed for viability of attached cells and alkaline phosphatase specific activity. In addition, mRNA expression levels of osteopontin and collagen type I were assessed using semi-quantitative RT-PCR. Over the observation period, cell viability, alkaline phosphatase activity and the expression of osteopontin and collagen type I mRNA were slightly enhanced in cells irradiated with 1 J/cm2 compared with untreated control cells. Increasing the laser dose to 2 J/cm2 reduced cell viability during the first 48 h and resulted in persistently lower alkaline phosphatase activity compared with the other two groups. The expression of osteopontin and collagen type I mRNA slightly decreased with time in untreated controls and cells irradiated with 1 J/cm2, but their expression was increased by treatment with 2 J/cm2 after 72 h. These results indicate that low-level laser therapy has a biostimulatory effect on human osteoblast-like cells during the first 72 h after irradiation. Further studies are needed to determine the potential of low-level laser therapy as new treatment concept in bone regeneration.     

Chiropractic manipulative therapy and low-level laser therapy in the management of cervical facet dysfunction: a randomized controlled study

Purpose

The aim of this study was to determine the short-term effect of chiropractic joint manipulation therapy (CMT) and low-level laser therapy (LLLT) on pain and range of motion in the management of cervical facet dysfunction.

Methods

Sixty ambulatory women between the ages of 18 and 40 years with cervical facet joint pain of more than 30-day duration and normal neurologic examination were randomized to receive 1 of 3 treatment options: (1) CMT of the cervical spine, (2) LLLT applied to the cervical facet joints, or (3) a combination of CMT and LLLT. Each participant received 6 treatments in 3 weeks. The main outcome measures were as follows: the Numerical Pain Rating Scale, Neck Disability Index, Cervical Range of Motion Instrument, and Baseline Digital Inclinometer. Measurements were taken during weeks 1 (baseline), 2, 3, and 4.

Results

No differences existed between the 3 groups at baseline. A significant difference was seen between groups 1 (CMT) and 2 (LLLT) for cervical flexion, between groups 1 (CMT) and 3 (CMT + LLLT) for cervical flexion and rotation, and between groups 2 (LLLT) and 3 (CMT + LLLT) for pain disability in everyday life, lateral flexion, and rotation.

Conclusion

All 3 groups showed improvement in the primary and secondary outcomes. A combination of CMT and LLLT was more effective than either of the 2 on their own. Both therapies are indicated as potentially beneficial treatments for cervical facet dysfunction. Further studies are needed to explore optimal treatment procedures for CMT and LLLT and the possible mechanism of interaction between therapies.     

Effects of low-level laser therapy (LLLT) of 810 nm upon in vitro growth of bacteria: relevance of irradiance and radiant exposure

OBJECTIVE: The aim of this study was to investigate the irradiance-dependency of low-level laser therapy (LLLT) effects on bacterial growth. BACKGROUND: LLLT is applied to open wounds to improve healing; however, its effect on wound bacteria is not well understood. MATERIALS AND METHODS: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were irradiated using a wavelength of 810 nm at irradiances of 0.015 W/cm2 (0-50 J/cm2) and 0.03 W/cm2 (0-80 J/cm2). Bacteria were counted after 20 h of incubation. RESULTS: LLLT effects varied significantly with species. P.aeruginosa growth decreased overall dependent on an interaction of irradiance and radiant exposure; greatest inhibition was produced using high irradiance delivering radiant exposures in the range of 1-20 J/cm2 (p = 0.001-0.04). In contrast, E. coli growth increased overall (p = 0.01), regardless of irradiance; greatest effects were produced using low radiant exposures (1-20 J/cm2). There was a main effect for irradiance (p = 0.03) on S. aureus growth; however, growth was not different compared with controls. Additional analysis showed that there were differences in growth of P.aeruginosa when comparing samples that were matched by exposure times (66, 329, 658, 1316, 1974, and 2632 sec) rather than radiant exposure; this suggests that irradiance rather than exposure time was the significant factor in P. aeruginosa inhibition. CONCLUSION: These findings have immediate relevancy in the use of LLLT for infected wounds. Exposure to 810-nm irradiation (0.03 W/cm2) could potentially benefit wounds infected with P. aeruginosa. However, increased E. coli growth could further delay recovery.     

Computerized morphometric assessment of the effect of low-level laser therapy on bone repair: an experimental animal study

OBJECTIVE: The aim of this study was to evaluate morphometrically the amount of newly formed bone after GaAlAs laser irradiation of surgical wounds created in the femur of rats. BACKGROUND DATA: Low-level laser therapy (LLLT) has been used in several medical specialties because of its biomodulatory effects on different biological tissues. However, LLLT is still controversial because of contradictory reports. This is a direct result of the different methodologies used in these works. MATERIALS AND METHODS: In this study, 40 Wistar rats were divided into four groups of 10 animals each: group A (12 sessions, 4.8 J/cm2 per session, observation time of 28 days); group C (three sessions, 4.8 J/cm2 per session, observation time of 7 days). Groups B and D acted as nonirradiated controls. The specimens were routinely processed to wax and cut at 6-microm thickness and stained with H&E. For computerized morphometry, Imagelab software was used. RESULTS: Computerized morphometry showed a significant difference between the areas of mineralized bone in groups C and D (p = 0.017). There was no difference between groups A and B (28 days; p = 0.383). CONCLUSION: It is concluded that, under this experimental condition, LLLT increased bone repair at early bone healing.     

低强度氦-氖激光血管内照射对缺血性脑卒中患者血管内皮功能的影响

目的：探讨低强度氦－氖激光血管内照射疗法（ILLI）对缺血性脑卒中患者血管内皮功能的影响。方法：将48例缺血性脑卒中患者随机分为常规组和ILLI治疗组，ILLI治疗组在常规治疗组的基础上加用ILLI疗效。两组病人均于入院的次日及第29天应用高分辨率超声检测肱动脉流量介导的舒张活性（FMD）变化。结果：经四周的治疗后，两组的FMD值均较各自治疗前显著升高，但ILLI组的FMD升高较常规组更为显著。结论：低强度氦－氖激光血管内照射疗法能有效改善缺血性脑卒中患者的血管内皮功能。     

A pilot study into the effect of low-level laser therapy in patients with chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a common inflammatory disease of the nose and paranasal sinuses that has a significant impact on patients' quality of life. No study has examined the effectiveness of applying low-level laser therapy (LLLT) locally over the sinuses in patients with CRS. The aim of this study was to evaluate the effect of LLLT in patients with CRS. Fifteen adult patients with CRS participated in this pilot pretest–posttest clinical study. Patients were treated with a 830-nm Ga-Al-As laser in continuous-wave mode at a power output of 30 mW and energy dose of 1 J. Laser irradiation was delivered on six points over each maxillary or frontal sinus with 33 sec irradiation for each point and a total treatment duration of 198 sec for each sinus. Patients were given LLLT three times per week for ten treatment sessions. Patients were asked to score their symptoms in accordance with a four-point scale (0–3), and a total symptom score (TSS) for each patient was calculated. Percentage improvement of TSS was considered as the primary outcome measure. TSS was calculated at baseline (T0), at 2 weeks (T1) and at 4 weeks (T2). The TSS was improved significantly at T1 (39%) and at T2 (46.34%). A large effect size for LLLT was found (η_p² η_p² = 0.63). The therapeutic effect was sustained for a mean of 5 months. This pilot study indicates that LLLT applied for 4 weeks improves symptoms in patients with CRS.     

Effect of low-level laser therapy on postoperative endodontic pain: An updated systematic review

ObjectiveTo evaluate the influence of low-level laser therapy (LLLT) on postoperative pain after endodontic treatment.MethodsThe PICOS strategy was used to identify randomized clinical trials comparing low-level laser therapy and mock laser therapy to manage postoperative pain after endodontic treatment, retreatment, and endodontic surgery. An electronic search was performed in MEDLINE through PubMed, Web of Science, LILACS, Scopus and Cochrane Library, OpenGrey and Google Scholar. Quality assessment was performed using the Cochrane Collaboration’s tool for assessing the risk of bias. The quality of evidence was rated on the basis of the GRADE approach.ResultsTwelve studies were included in the qualitative synthesis. Within the 12 studies, 7 articles were classified as “low risk of bias,” 4 studies were considered “unclear risk of bias” and 1 study was considered "high risk of bias." Six studies evaluated the postoperative pain after primary root canal treatment, two studies after root canal retreatment and four after periapical surgery. Most of the studies reported significantly less postoperative pain after LLLT in different time periods; two studies found no differences. The certainty of evidence was classified as low and very low to treatment / retreatment and endodontic surgery, respectively.ConclusionsBased on the limited quality evidence, most of the included studies reported significantly less postoperative pain after LLLT. However, the lack of standardization in laser parameters, use of medications and the certainty of evidence classified as low and very low indicate the need for further studies.     

Differential responses of fibroblasts,non-neoplastic epithelial cells,and oral carcinoma cells to low-level laser therapy

Low-level laser therapy (LLLT) is used in the treatment of chemoradiotherapy- or radiotherapy-induced oropharyngeal mucositis (ORM). In head and neck cancer, tumor cells may lie in the LLLT irradiation field, and LLLT might promote tumor progression. We therefore investigated the effect of LLLT on proliferation, cell cycle distribution, and apoptosis in a human oral carcinoma cell line (SCC-25), non-malignant epithelial cells (BEAS-2B), and fibroblasts in vitro. The cell lines were subjected to LLLT on three consecutive days for 15 min. Cell proliferation was assessed using the MTT assay, cell cycle distribution by flow cytometry and propidium-iodide DNA staining, and apoptosis using an Annexin V-FITC assay. Controls were sham-treated, but not exposed to the laser treatment. LLLT treatment resulted in increased fibroblast proliferation (p < 0.001), whereas decreased cell proliferation was observed after LLLT treatment of BEAS-2B (p = 0.003) and SCC-25 cells (p < 0.001). In SCC-25 cells, an increased percentage of S-phase cells and decreased percentage of G1-phase cells were observed (p < 0.001). Moreover, a proapoptotic effect of LLLT was observed in SCC-25 cells (p = 0.02). LLLT did not exhibit a tumor-promoting effect in this in vitro study.     

The effectiveness of low-level laser therapy on shoulder function in subacromial impingement syndrome

Purpose. To investigate the effectiveness of low-level laser therapy (LLLT) in addition to exercise programme on shoulder function in subacromial impingement syndrome (SAIS).

Method. Sixty-seven patients with SAIS were randomly assigned to either a group that received laser (n = 34) or a group that received placebo Laser (n = 26). Pain, functional assessment, disability and muscle strength of shoulder were assessed before and after a 3-week rehabilitation programme. Besides Laser or placebo Laser, superficial cold and progressive exercise programme were administered to both groups, 5 days a week, for 3 weeks. A progressive exercise programme that was done daily twice under supervision in clinic and at home was given to the patients.

Results. After the treatment, all outcome measurements had shown significant improvement except muscle strength in both the groups. When the parameters of the improvement were compared, there were no significant differences between the two groups after treatment.

Conclusion. We concluded that there is no fundamental difference between LLLT and placebo LLLT when they are supplementing an exercise programme for rehabilitation of patients with shoulder impingement syndrome.     

低功率半导体激光照射对体外培养嗅鞘细胞的影响

目的研究低功率810 nm半导体激光对体外培养嗅黏膜嗅鞘细胞增殖的影响。 方法取成年SD大鼠嗅黏膜,采用差速贴壁法获得嗅鞘细胞,对细胞进行不同功率密度的半导体激光照射,波长为810 nm,在10.3 mW/cm2功率密度下分别照射30,60,120 s,每日1次,连续3 d,各次间隔24 h。最后一次照射后细胞培养。主细胞培养第3,5,8天时采用细胞计数法和四氮唑蓝（MTT）法分别检测照射后不同时间细胞增殖的变化。 结果最后一次照射后细胞培养第3天时,不同时间照射组和对照组细胞增殖无差异。细胞培养第5天和第8天时,不同时间照射组细胞数均高于对照组,差异有统计学意义（P＜0.05）;60 s和120 s照射组OD值高于对照组,差异有统计学意义（P＜0.05）;但30 s照射组OD值与对照组差异无统计学意义。其中以60 s照射组细胞增殖最为明显。 结论低功率半导体激光对体外培养嗅黏膜嗅鞘细胞的增殖有促进作用,其作用与照射的时间剂量有关。最佳照射时间是每日1次,连续3 d,各次间隔24 h。     

The short-term effects of low-level laser therapy in the management of breast-cancer-related lymphedema

Background  

Breast-cancer-related lymphedema (BCRL) is a chronic disease, and currently there is no definitive treatment for it. There are some therapeutic interventions targeted to decrease the limb swelling and the associated problems. Low-level laser therapy (LLLT) has been used in the treatment of post-mastectomy lymphedema since 2007 in the US. The aim of this study is to review our short-term experience with LLLT in the treatment of BCRL.     

弱激光照射对早期内毒素血症大鼠胃黏膜的效应

目的 探讨弱激光照射对早期内毒素血症(endotoxemia, ETM)大鼠胃黏膜变化的效应.方法 采用脂多糖(LPS)静脉注射法建立ETM疾病模型.60只SD大鼠随机分为对照组、内毒素损伤组和弱激光照射组,每组20只.弱激光组在注射LPS 30 min后以SLT半导体激光治疗仪对大鼠的股动、静脉和耳部血管同时进行照射,治疗参数为波长650 nm、功率5 mW,一次性垂直照射30 min.在ETM形成1、2、4、6 h后,检测胃液pH值,观察胃黏膜组织病理学变化.结果 胃液pH值在ETM形成6 h内尚未发生变化,但此时大鼠胃黏膜已有组织学改变,主要表现为胃黏膜上皮细胞损伤、脱落,局部充血、水肿、渗出及炎性细胞浸润;经弱激光照射后胃黏膜炎性反应明显减轻.结论 这种SD大鼠早期ETM疾病模型在6 h内胃液pH值未发生变化,但胃黏膜已有形态学变化,弱激光照射可减轻早期的病理损伤.     

Anti-inflammatory and analgesic effects of low-level laser therapy on the postoperative healing process

[Purpose] This study aimed to evaluate the anti-inflammatory and analgesic effects of intraoral application of low-level laser therapy (660 nm) to control pain, swelling and interincisal opening following the extraction of mandibular third molars. [Subjects and Methods] Ten patients underwent removal of lower third molars using the same surgical protocol and pharmacological approach. In the postoperative period, all patients received four consecutive daily sessions of low-level laser therapy, beginning 24 hours after the surgery. Intraoral applications using the diode laser with 660 nm wavelength in the continuous scan mode were performed covering the entire surgical area, which was divided into four quadrants, each of 1 cm² area at a distance of 1 cm. The energy applied at each point was 5 J/cm² during 8 seconds. [Results] The swelling and interincisal opening returned to normal 24 hours after the first low-level laser therapy application (Friedman test). Moreover, the pain intensity was reduced on the third postoperative day, according to the Friedman test. [Conclusion] Low-level laser therapy (660 nm), at the dosimetry used in this study, was effective in reducing postoperative pain and swelling following oral surgery.Key words: Low-level laser therapy, Rehabilitation, Inflammation     

Effects of platinum-thymine on mitosis of sarcoma-180 ascites cells in vitro: ultrastructural study

Electron microscopic studies of sarcoma-180 ascites cells, which were treated with platinum-thymine at a concentration of 60 micrograms/ml, showed mitotic inhibition. The drug clumped the chromosomes into a compact mass at the center of the cell preventing them from separating during mitosis. Prolonged treatment depolymerized spindle fibers and cytoplasmic microfilament. Degraded cytoplasmic organelles crowded around the clumped chromosomes. Disintegrating and casting off of cortical cytoplasm was apparent. Platinum-thymine-treated cells did not resume mitosis irrespective of the amount of time they were allowed to remain in fresh medium. Perturbation of mitotic machinery by platinum-thymine inhibited the mitotic process and caused eventual demise of the cancer cells.     

Bisphosphonate-related osteonecrosis of the jaw: a review of the potential efficacy of low-level laser therapy

Osteonecrosis of the jaw (ONJ) resulting from administration of bisphosphonates (BP) or denosumab is a rare but severe complication in cancer patients. Complete remission depends on the stage of ONJ; it can be estimated in the range of 20–30 %. Low-level laser therapy (LLLT) is a logical additional option, as it has been recognized effective for the management of chemotherapy and/or radiotherapy-induced mucositis. LLLT irradiation has anti-inflammatory actions and thus can help to control pain, as well as biostimulating properties with favorable actions on bacterial control and wound healing. We review the results of seven published studies of LLLT in BP-associated ONJ. LLLT results in an overall response rate of 55 % superior to that observed in controls (30 %). Our review suggests that there might be an advantage to add LLLT to the “classical” management of ONJ. This therapy is easy to administer and is not associated with any known side effects. Further research is needed to remove any doubt of protection or enhancement of carcinogenic processes. We believe that prospective well-controlled studies of LLLT in ONJ are warranted. If the positive results are confirmed, it would represent a great improvement for the quality of life of many patients.     

Effect of low-level laser therapy on the modulation of the mitochondrial activity of macrophages

BACKGROUND:

Macrophages play a major role among the inflammatory cells that invade muscle tissue following an injury. Low-level laser therapy (LLLT) has long been used in clinical practice to accelerate the muscle repair process. However, little is known regarding its effect on macrophages.

OBJECTIVE:

This study evaluated the effect of LLLT on the mitochondrial activity (MA) of macrophages.

METHOD:

J774 macrophages were treated with lipopolysaccharide (LPS) and interferon - gamma (IFN-γ) (activation) for 24 h to simulate an inflammatory process, then irradiated with LLLT using two sets of parameters (780 nm; 70 mW; 3 J/cm² and 660 nm; 15 mW; 7.5 J/cm²⁾. Non-activated/non-irradiated cells composed the control group. MA was evaluated by the cell mitochondrial activity (MTT) assay (after 1, 3 and 5 days) in three independent experiments. The data were analyzed statistically.

RESULTS:

After 1 day of culture, activated and 780 nm irradiated macrophages showed lower MA than activated macrophages, but activated and 660 nm irradiated macrophages showed MA similar to activated cells. After 3 days, activated and irradiated (660 nm and 780 nm) macrophages showed greater MA than activated macrophages, and after 5 days, the activated and irradiated (660 nm and 780 nm) macrophages showed similar MA to the activated macrophages.

CONCLUSIONS:

These results show that 660 nm and 780 nm LLLT can modulate the cellular activation status of macrophages in inflammation, highlighting the importance of this resource and of the correct determination of its parameters in the repair process of skeletal muscle.