Effect of low-level laser therapy on types I and III collagen and inflammatory cells in rats with induced third-degree burns

Low-level laser therapy (LLLT) has been increasingly used to accelerate wound healing in third-degree burns. This study investigated the effects of lasers on the tissue repair process of third-degree burns. Burns were produced on the backs of male Wistar rats. The animals were divided into four groups (n?=?12): control, injury, LLLT 3 J/cm², and LLLT 4 J/cm². Each group was further divided into two subgroups; the rats in one subgroup were killed on day 8 and those in the other, on day 16 after injury. The animals in LLLT 3 J/cm² and LLLT 4 J/cm² were irradiated 1 h after injury, and irradiation was repeated every 48 h. Laser (660 nm, 35 mW) treatment at fluences of 3 and 4 J/cm² were used. After killing the rats, tissue fragments from the burnt area were removed for histological analysis. The LLLT-treated groups showed a significant decrease (p <0.05) in the number of inflammatory cells and increased collagen deposition compared to the injury group. Laser irradiation (both 3 and 4 J/cm²) resulted in reduction in the inflammatory process and improved collagen deposition, thereby ameliorating the healing of third-degree burns.     

Role of mast cells in the pathogenesis of postburn inflammatory response: reactive oxygen species as mast cell stimulators

Thermal trauma has a direct effect on mast cells, triggering the secretion of histamine. This secretion leads to an enhanced xanthine oxidase activity and an increased production of reactive oxygen species (ROS), the latter being produced after burns through differing mechanisms. As ROS have been shown to have deleterious effects on cellular membranes, a lesion of the mast cell membrane could close the circle of autoinjury due to the vasoactive actions of mast cell mediators. Our studies were designed to assess the potentiality of ROS as stimulators of mast cell degranulation after burns by comparing two groups of rats treated, respectively, with SOD and saline solution after a scald injury. Plasma levels of tryptase and histamine were analyzed as markers of mast cell activity. A comparison of the mean increases of tryptase between baseline and 3-h postburn levels in the two groups shows significant differences (p < 0.001) (control: 0.13+/-0.04, SOD: 0.03+/-0.01). When comparing the mean increases between the baseline and 3 h postburn levels of histamine in the two groups, significant differences were also found (p < 0.001) (control group: 2.70+/-0.57. SOD group: 1.22+/-0.32). The lower levels of histamine and tryptase induced by SOD provides indirect evidence that ROS are involved in the process, causing the release of such mediators by mast cells, which may in turn suggest that ROS can act as stimulators of mast cell degranulation in burns.     

Effect of low-level laser therapy on skin fibroblasts of streptozotocin-diabetic rats

OBJECTIVE: This study explored the effects of low-level laser therapy (LLLT) on cellular changes in cell culture and organ culture of skin from streptozotocin-diabetic (STZ-D) rats. BACKGROUND DATA: Growth of skin and its fibroblasts are impaired in diabetes. Therefore the healing of skin wounds is impaired in diabetic patients. The positive effects of LLLT on complications of diabetes in patients and animal models have been shown. METHODS: Diabetes was induced in rats by streptozotocin 30 days after its injection. Two sets of skin samples were extracted from skin under sterile conditions. Fibroblasts that were extruded from the samples were proliferated in vitro, and another set of samples were cultured as organ culture. A 24-well culture medium containing Dulbecco's modified minimum essential medium was supplemented by 12% fetal bovine serum. There were five laser-treated and five sham-exposed groups. A helium-neon laser was used, and 0.9-4 J/cm(2) energy densities were applied four times to each organ culture and cell culture. The organ cultures were analyzed by light microscopy and transmission electron microscopy examinations. Cell proliferation was evaluated by dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. RESULTS: Statistical analysis revealed that 4-J/cm(2) irradiation significantly increases the fibroblast numbers compared to the sham-exposed cultures (p = 0.046). CONCLUSION: It is concluded that LLLT resulted in a significant increase of fibroblast proliferation of STZ-D rats in vitro.     

肝素对大鼠Ⅱ度烧伤创面愈合的影响

目的　研究肝素对大鼠 度烧伤创面愈合的影响。方法　 2 0只 SD大鼠随机分为两组 ,制成2 0 %面积深 度烧伤 ,实验组采用肝素 10 0 U /kg加生理盐水至 1ml皮下注射 ;对照组采用生理盐水 1ml皮下注射 ,每天一次直至创面完全愈合。从大体观察创面愈合天数及全身有无出血现象 ,光镜观察肉芽组织及胶原纤维生长情况 ,电镜观察成纤维细胞生长情况。结果　大鼠全部成活。实验组创面愈合时间为 (2 2 .8± 1.87)天 ,对照组为(2 6 .2± 2 .82 )天 ,实验组创面愈合所需时间明显少于对照组 (P<0 .0 0 5 )。光镜观察发现实验组肉芽组织及胶原纤维生长明显优于对照组。电镜观察发现实验组成纤维细胞生长优于对照组。结论　肝素皮下注射能加速创面愈合。     

Transcranial application of low-energy laser irradiation improves neurological deficits in rats following acute stroke

BACKGROUND AND OBJECTIVES: Low-level laser therapy (LLLT) has been shown to have beneficial effects on ischemic skeletal and heart muscles tissues. The aim of the present study was to approve the effectiveness of LLLT treatment at different locations on the brain in acute stroked rats. STUDY DESIGN/MATERIALS AND METHODS: Stroke was induced in 169 rats that were divided into four groups: control non-laser and three laser-treated groups where laser was employed ipsilateral, contralateral, and both to the side of the induced stroke. Rats were tested for neurological function. RESULTS: In all three laser-treated groups, a marked and significant improvement in neurological deficits was evident at 14, 21, and 28 days post stroke relative to the non-treated group. CONCLUSIONS: These observations suggest that LLLT applied at different locations in the skull and in a rather delayed-phase post stroke effectively improves neurological function after acute stroke in rats.     

Effect of equal daily doses achieved by different power densities of low-level laser therapy at 635 nm on open skin wound healing in normal and corticosteroid-treated rats

Optimal parameters of low-level laser therapy (LLLT) for wound healing are still discussed. Hence, our study was aimed to compare effects of different power densities of LLLT at 635 nm in rats. Four, round, full-thickness, skin wounds were made on the backs of 48 rats that were divided into two groups (non-steroid laser-treated and steroid laser-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm²) each with different power density (1 mW/cm², 5 mW/cm², and 15 mW/cm²), whereas the fourth wound served as a control. Two days, 6 days, and 14 days after surgery, eight animals from each group were killed and samples were removed for histological evaluation. In the non-steroid laser-treated rats, significant acceleration of epithelization and collagen synthesis 2 days and 6 days after surgery was observed in stimulated wounds. In steroid laser-treated rats, 2 days and 14 days after surgery, a decreased leucocyte/macrophage ratio and a reduction in the area of granulation tissue were recorded, respectively. In conclusion, LLLT, by the method we used, improved wound healing in the non-steroid laser-treated rats, but it was useless after corticosteroid treatment.     

An evaluation of the effect of pulsed wave low-level laser therapy on the biomechanical properties of the vertebral body in two experimental osteoporosis rat models

Osteoporosis (OP) increases vertebral fragility as a result of the biomechanical effects of diminished bone structure and composition. This study has aimed to assess the effects of pulsed wave low-level laser therapy (PW LLLT) on cancellous bone strength of an ovariectomized (OVX-d) experimental rat model and a glucocorticoid-induced OP (GIOP) experimental rat model. There were four OVX-d groups and four dexamethasone-treated groups. A group of healthy rats was used for baseline evaluations. The OVX-d rats were further subdivided into the following groups: control rats with OP, OVX-d rats that received alendronate, OVX-d rats treated with PW LLLT, and OVX-d rats treated with alendronate and PW LLLT. The remaining rats received dexamethasone and were divided into four groups: control, alendronate-treated rats, laser-treated rats, and laser-treated rats with concomitant administration of alendronate. PW LLLT (890 nm, 80 Hz, 0.972 J/cm²) was performed on the spinal processes of the T12, L1, L2, and L3 vertebras. We extracted the L1 vertebrae and submitted them to a mechanical compression test. Biomechanical test findings showed positive effects of the PW LLLT and alendronate administration on increasing bending stiffness and maximum force of the osteoporotic bones compared to the healthy group. However, laser treatment of OVA-d rats significantly increased stress high load compared to OVA-d control rats. PW LLLT preserved the cancellous (trabecular) bone of vertebra against the detrimental effects of OV-induced OP on bone strength in rats compared to control OV rats.     

Effects of different fluences of low-level laser therapy in an experimental model of spinal cord injury in rats

The aim of this study was to evaluate the in vivo response of different fluences of low-level laser therapy (LLLT) on the area of the injury, inflammatory markers, and functional recovery using an experimental model of traumatic spinal cord injury (SCI). Thirty two rats were randomly divided into four experimental groups: control group (CG), laser-treated group 500 J/cm² (L-500), laser-treated group 750 J/cm² (L-750), and laser-treated group 1000 J/cm² (L-1000). SCI was performed by an impactor equipment (between the ninth and tenth thoracic vertebrae), with a pressure of 150 kdyn. Afterwards, the injured region was irradiated daily for seven consecutive sessions, using an 808-nm laser, at the respective fluence of each experimental groups. Motor function and tactile sensitivity were performed on days 1 and 7 post-surgery. Animals were euthanized on the eighth day after injury, and the samples were retrieved for histological and immunohistochemistry analyses. Functional evaluation and tactile sensitivity were improved after LLLT, at the higher fluence. Additionally, LLLT, at 750 and 1000 J/cm², reduces the lesion volume and modulates the inflammatory process with decrease of CD-68 protein expression. These results suggest that LLLT at higher doses was effective in promoting functional recovery and modulating inflammatory process in the spinal cord of rats after SCI.     

LED (660 nm) and laser (670 nm) use on skin flap viability: angiogenesis and mast cells on transition line

Skin flap procedures are commonly used in plastic surgery. Failures can follow, leading to the necrosis of the flap. Therefore, many studies use LLLT to improve flap viability. Currently, the LED has been introduced as an alternative to LLLT. The objective of this study was to evaluate the effect of LLLT and LED on the viability of random skin flaps in rats. Forty-eight rats were divided into four groups, and a random skin flap (10?×?4 cm) was performed in all animals. Group 1 was the sham group; group 2 was submitted to LLLT 660 nm, 0.14 J; group 3 with LED 630 nm, 2.49 J, and group 4 with LLLT 660 nm, with 2.49 J. Irradiation was applied after surgery and repeated on the four subsequent days. On the 7th postoperative day, the percentage of flap necrosis was calculated and skin samples were collected from the viable area and from the transition line of the flap to evaluate blood vessels and mast cells. The percentage of necrosis was significantly lower in groups 3 and 4 compared to groups 1 and 2. Concerning blood vessels and mast cell numbers, only the animals in group 3 showed significant increase compared to group 1 in the skin sample of the transition line. LED and LLLT with the same total energies were effective in increasing viability of random skin flaps. LED was more effective in increasing the number of mast cells and blood vessels in the transition line of random skin flaps.     

Effect of low-intensity laser therapy on mast cell degranulation in human oral mucosa

Little is known about the physiological mechanisms related to low-intensity laser therapy (LILT), particularly in acute inflammation and subsequent wound healing. The objective of this study was to verify the effect of LILT on mast cell degranulation. Epulis fissuratum tissues from eight patients were used. One part of the lesion was irradiated with an AsGaAl laser (λ?=? 670 nm, 8.0 J/cm², 5 mW, 4 min). The other part was not irradiated. Then, the specimens were immediately removed, fixed and examined by light microscopy. The number of mast cells was similar in laser-treated samples when compared with non-irradiated specimens. The degranulation indexes of the mast cells observed in the irradiated samples were significantly higher than those of controls (P?相似文献   

The effect of henna and linseed herbal ointment blend on wound healing in rats with second-degree burns

The treatment of skin burns is one of the most important challenge in medical science. The aim of this study is evaluation of the efficacy of Artaderm herbal ointment containing the Henna (Lawsonia inermis) extract, Linseed (Linum usitatissimum) oil, and Honey Wax on wound healing in the rat with second-degree burn wounds. The Artaderm ointment had an effective role in controlling burn wound infections due to its antimicrobial and anti-inflammatory properties. In this study, 64 male Wistar rats were randomly divided into 8 groups (n = 8). Four groups received Artaderm, 1% Silver Sulfadiazine (SSD 1%), Cod Liver Oil and Fundermol (Alpha) ointments which used in common practices for burn injuries. Another three groups received Henna, Linseed, and Honey Wax alone and a control group that just underwent a second-degree burn injury without any treatments. A second-degree burn was formed on the back of each rat and dressed daily with one of the agents. Burn wounds were macroscopically and microscopically evaluated on the 7th, 14th, and 21st day after burn induction. Rats treated with the Artaderm ointment had significantly faster wound contraction as well as shorter healing time than the rest groups. No scar was observed in rats treated with the Artaderm ointment on the 21st day, while this level of improvement was not observed in other groups at the same time. More than 90% of wounds were healed after on the 14th day in rats treated with Artaderm (94.10 ± 0.18) and Alpha (92.05 ± 0.23) ointments. According to these findings, it can be concluded that Artaderm herbal ointment can be used as a proper alternative for healing of wounds in second-degree burns.     

Comparison of the effect of multi-wavelength light produced by a cluster of semiconductor diodes and of each individual diode on mast cell number and degranulation in intact and injured skin

Intact skin and partial thickness wounds in adult male Wistar rats were irradiated by pulsed, monochromatic light of different spectral wavelength peaks simultaneously and the effects on mast cell number and degranulation were assessed. The light was produced by a Biotherapy 3ML (Omega Universal Technologies) device utilizing a 21 semiconductor diode cluster probe emitting 6 different wavelengths in the red and near infrared part of the spectrum simultaneously, only one of the wavelengths (820 nm) being coherent. The duration of treatment was 4 minutes. The average power density, distributed over the surface area of the probe (19.62 cm2) was 45 mW/cm2. The average energy density at the wound site was 10.8 J/cm2. The effect of each of the wavelengths incorporated in the cluster probe was then examined separately. The average power density for each single probe was 120 mW/cm2, except for the 820 nm diode which was 400 mW/cm2. The average energy density was maintained at 10.8 J/cm2 as with the cluster probe. After 2 hours the rats were killed and the skin was removed, processed for light microscopy, and stained with toluidine blue to identify the mast cells. The numbers of the intact and degranulated mast cells were counted in 100 high power fields (i.e., over a total area of 20 mm2) in each irradiated specimen and compared to the sham-irradiated and untreated groups. To avoid bias, the slides examined were coded and evaluated blind. In intact skin, the cluster probe irradiation was followed by a statistically significant increase in the total number of mast cells compared to the sham-irradiated group, but the percentage of the degranulated mast cells was not affected. In the partial thickness wound, the cluster probe irradiation was also followed by a statistically significant increase in the total number of mast cells compared to the sham-irradiated group; however, there was, in addition, a significant increase in the percentage of degranulated mast cells. Concerning the single probes, only the 660, 820, 940, and 950 nm wavelength emitters produced statistically significant increases in both mast cell number and degranulation in partial thickness wounds. However, when intact skin was irradiated with probes emitting these wavelengths, although the total number of mast cells was increased significantly, there was no change in degranulation compared with the sham-irradiated group. The effects observed were less than those of the cluster probe. No significant differences were found between the 870 and 880 nm wavelength-irradiated, sham-irradiated, and untreated groups in either intact or injured skin.(ABSTRACT TRUNCATED AT 400 WORDS)     

硝普钠和磺胺嘧啶银联合应用对大鼠深Ⅱ度烧伤创面愈合的影响

目的：研究硝普钠、磺胺嘧啶银及二者合用对深Ⅱ度烧伤皮肤创面愈合的影响。方法：100只WiStar大鼠背部深Ⅱ度烧伤创面,随机分成0．9％氯化钠注射液组、1％磺胺嘧啶银霜组、lmmol／L硝普钠组和1％磺胺嘧啶银霜＋lmmol／L硝普钠组。每组25只大鼠。动态观察烧伤后不同时间点创面细胞增殖周期、羟脯氨酸含量及创面组织愈合情况,计算创面愈合率。结果：伤后随时间推移磺胺嘧啶银霜＋硝普钠组创面愈合率高于其他三组;伤后第10天,磺胺嘧啶银霜＋硝普钠组创面羟脯氨酸含量、细胞S期百分比达到峰值,明显高于0．9％氯化钠注射液（P〈O．01）,磺胺嘧啶银霜组、硝普钠组之间比较无显著差异（P〉0．05）。结论：磺胺嘧啶银霜和硝普钠合用可有效促进大鼠深Ⅱ度烧伤创面愈合。     

Effects of lidocaine with epinephrine or with buffer on wound healing in rat skin

Lidocaine blocks nociceptive fibers, preventing initial wound signaling and mast cell degranulation. It is hypothesized that epinephrine and buffer affect the wound healing by potentiating lidocaine blockage. This double‐blind, randomized, self‐controlled study investigated this possibility using male Wistar rats, which were injected with 2 mL of different solutions into the left and right sides of the back. Then, each side was incised and sutured. Sixty rats were divided in three groups: saline solution (SS) and lidocaine; lidocaine and lidocaine with buffer; lidocaine with epinephrine and lidocaine with epinephrine and buffer. Half of each group was sacrificed 7 days after surgery and the remaining after 21 days. A sample of each wound was obtained and quantified for the level of collagen present using computer morphometry and for mast cell quantity. There were no differences between animals with regard to the collagen. However, mast cell levels in the same animal significantly differed between SS × lidocaine. Comparison of the same injected substance between animals with different healing dates showed a significant effect on collagen SS and on all mast cells, except SS. Lidocaine affected collagenization and decreased the initial quantity of mast cells at the wound site.     

Low-level laser therapy prevents degenerative morphological changes in an experimental model of anterior cruciate ligament transection in rats

The aim of this study was to analyze the effects of low-level laser therapy (LLLT) on the prevention of cartilage damage after the anterior cruciate ligament transection (ACLT) in knees of rats. Thirty male rats (Wistar) were distributed into three groups (n?=?10 each): injured control group (CG); injured laser-treated group at 10 J/cm² (L10), and injured laser-treated group at 50 J/cm² (L50). Laser treatment started immediately after the surgery and it was performed for 15 sessions. An 808 nm laser, at 10 and 50 J/cm², was used. To evaluate the effects of LLLT, the qualitative and semi-quantitative histological, morphometric, and immunohistochemistry analysis were performed. Initial signs of tissue degradation were observed in CG. Interestingly, laser-treated animals presented a better tissue organization, especially at the fluence of 10 J/cm². Furthermore, laser phototherapy was able of modulating some of the aspects related to the degenerative process, such as the prevention of proteoglycans loss and the increase in cartilage area. However, LLLT was not able of modulating chondrocytes proliferation and the immunoexpression of markers related to inflammatory process (IL-1 and MMP-13). This study showed that 808 nm laser, at both fluences, prevented features related to the articular degenerative process in the knees of rats after ACLT.     

银离子抗菌凝胶用于Ⅱ度烧伤创面的疗效观察

目的:观察银离子抗菌凝胶应用于烧伤创面的临床效果。方法:选择烧伤深度基本一致,面积相近、相邻部位或对称部位的浅Ⅱ度、深Ⅱ度创面患者60例,随机分为两组。试验组应用银离子抗菌凝胶敷料,对照组外用1%磺胺嘧啶银乳膏,对两组同期愈合率、愈合时间、抗菌性三方面进行对比。结果:两组药物在浅Ⅱ度、深Ⅱ度创面的同期愈合率、愈合时间方面比较无明显差异。在抗菌性方面银离子抗菌凝胶明显优于磺胺嘧啶银软膏。结论:银离子抗菌凝胶与其他形式银制剂相比具有良好的抑菌作用。     

The influence of red laser irradiation timeline on burn healing in rats

Low-level laser therapy (LLLT) promotes biomodulation of wound healing and literature reports that light delivery during the inflammation could play a different role compared with latter phases of the healing process. The objective of this study was to investigate whether single dose of a red laser (λ?=?660 nm) is different from fractionated delivery protocol in full thickness burns. Two lesions were inflicted on the back of 36 rats. In the fractionated dose group (FG), the lesions were irradiated with 1 J/cm² on days 1, 3, 8, and 10 post-wounding. In the single dose group (SG), the lesions were irradiated with 4 J/cm² on day 1, immediately after injury. Control lesions (CG) received no light and were left to heal spontaneously. Blood flow was measured on days 1, 3, 8, 10, 15, and 21 using laser Doppler flowmetry. Animals were killed on days 3, 8, 10, 15, and 21. Skin specimens were obtained and routinely processed for hematoxylin and eosin. The specimens were evaluated according to differential leukocyte counting and angiogenesis. Statistical analysis was performed, and significance was accepted at p?<?0.05. Irradiated groups showed a peak of new vessels on day 15 while, for CG, the peak was on day 21. On day 21, FG exhibited a significantly greater number of cumulative neutrophils while SG showed a higher number of mononuclear cells. Our results confirm that both protocols used accelerate angiogenesis and stimulate leukocyte chemotaxis on burn treatment. In addition, this work suggests that a single-dose LLLT accelerates the inflammatory phase of skin repair.     

Effect of laser therapy on skeletal muscle repair process in diabetic rats

Skeletal muscle myopathy is a common source of disability in diabetic patients. This study evaluated whether low-level laser therapy (LLLT) influences the healing morphology of injured skeletal muscle. Sixty-five male Wistar rats were divided as follows: (1) sham; (2) control; (3) diabetic; (4) diabetic sham; (5) nondiabetic cryoinjured submitted to LLLT (LLLT); (6) diabetic cryoinjured submitted to LLLT (D-LLLT); and (7) diabetic cryoinjured non-treated (D). Diabetes was induced with streptozotocin. Anterior tibialis muscle was cryoinjured and received LLLT daily (780 nm, 5 J/cm², 10 s per point; 0.2 J; total treatment, 1.6 J). Euthanasia occurred on day 1 in groups 1, 2, 3, and 4 and on days 1, 7, and 14 in groups 5, 6, and 7. Muscle samples were processed for H&E and Picrosirius Red and photographed. Leukocytes, myonecrosis, fibrosis, and immature fibers were manually quantified using the ImageJ software. On day 1, all cryoinjured groups were in the inflammatory phase. The D group exhibited more myonecrosis than LLLT group (p?<?0.05). On day 14, the LLLT group was in the remodeling phase; the D group was still in the proliferative phase, with fibrosis, chronic inflammation, and granulation tissue; and the D-LLLT group was in an intermediary state in relation to the two previous groups. Under polarized light, on day 14, the LLLT and D-LLLT groups had organized collagen bundles in the perimysium, whereas the diabetic groups exhibited fibrosis. LLLT can have a positive effect on the morphology of skeletal muscle during the tissue repair process by enhancing the reorganization of myofibers and the perimysium, reducing fibrosis.     

Evaluation of the effects of pulsed wave LLLT on tibial diaphysis in two rat models of experimental osteoporosis,as examined by stereological and real-time PCR gene expression analyses

Osteoporosis (OP) and osteoporotic fracture are major public health issues for society; the burden for the affected individual is also high. Previous studies have shown that pulsed wave low-level laser therapy (PW LLLT) has osteogenic effects. This study intended to evaluate the impacts of PW LLLT on the cortical bone of osteoporotic rats’ tibias in two experimental models, ovariectomized and dexamethasone-treated. We divided the rats into four ovariectomized induced OP (OVX-d) and four dexamethasone-treated (glucocorticoid-induced OP, GIOP) groups. A healthy (H) group of rats was considered for baseline evaluations. At 14 weeks following ovariectomy, we subdivided the OVX-d rats into the following groups: (i) control which had OP, (ii) OVX-d rats treated with alendronate (1 mg/kg), (iii) OVX-d rats treated with LLLT, and (iv) OVX-d rats treated with alendronate and PW LLLT. The remaining rats received dexamethasone over a 5-week period and were also subdivided into four groups: (i) control rats treated with intramuscular (i.m.) injections of distilled water (vehicle), (ii) rats treated with subcutaneous alendronate injections (1 mg/kg), (iii) laser-treated rats, and (iv) rats simultaneously treated with laser and alendronate. The rats received alendronate for 30 days and underwent PW LLLT (890 nm, 80 Hz, 0.972 J/cm²) three times per week during 8 weeks. Then, the right tibias were extracted and underwent a stereological analysis of histological parameters and real-time polymerase chain reaction (RT-PCR). A significant increase in cortical bone volume (mm³) existed in all study groups compared to the healthy rats. There were significant decreases in trabecular bone volume (mm³) in all study groups compared to the group of healthy rats. The control rats with OP and rats from the vehicle group showed significantly increased osteoclast numbers compared to most other groups. Alendronate significantly decreased osteoclast numbers in osteoporotic rats. Concurrent treatments (compounded by PW LLLT and alendronate) produce the same effect on osteoporotic bone.     

Effect of low-level laser therapy on cochlear hair cell recovery after gentamicin-induced ototoxicity

Cochlear hair cells are the sensory receptors of the auditory system. It is well established that antibiotic drugs such as gentamicin can damage hair cells and cause hearing loss. Rescuing hair cells after ototoxic injury is an important issue in hearing recovery. Although many studies have indicated a positive effect of low-level laser therapy (LLLT) on neural cell survival, there has been no study on the effects of LLLT on cochlear hair cells. Therefore, the aim of this study was to elucidate the effects of LLLT on hair cell survival following gentamicin exposure in organotypic cultures of the cochlea of rats. The cochlea cultures were then divided into a control group (n?=?8), a laser-only group (n?=?8), a gentamicin-only group (n?=?8) and a gentamicin plus laser group (n?=?7). The control cultures were allowed to grow continuously for 11?days. The laser-only cultures were irradiated with a laser with a wavelength of 810?nm at 8?mW/cm(2) for 60?min per day (0.48?J/cm(2)) for 6?days. The gentamicin groups were exposed to 1?mM gentamicin for 48?h and allowed to recover (gentamicin-only group) or allowed to recover with daily irradiation (gentamicin plus laser group). The hair cells in all groups were stained with FM1-43 and counted every 3?days. The number of hair cells was significantly larger in the gentamicin plus laser group than in the gentamicin-only group. The number of hair cells was larger in the laser-only group than in the control group, but the difference did not reach statistical significance. These results suggest that LLLT may promote hair cell survival following gentamicin damage in the cochlea. This is the first study in the literature that has demonstrated the beneficial effect of LLLT on the recovery of cochlear hair cells.