Low-level laser therapy (LLLT) accelerates the sternomastoid muscle regeneration process after myonecrosis due to bupivacaine

Effect of Infrared and Green Photomodulation Exposure on the Number of Active Myosatellite Cells in Regenerating Muscles

Reparative properties of infrared laser exposure are well known, but the effects of green laser light are little studied. We analyzed the effects of short (60 sec) and longer (180 sec) exposure to infrared (980 nm) and green (520 nm) laser on the number of activated myosatellite cells in the regenerating m. gastrocnemius of Wistar rats after infliction of an incision wound. Histological preparations were used for morphometric evaluation of myosatellite cells with MyoD+ nuclei. Increased numbers of MyoD+ nuclei were observed on days 3 and 7 after 60-sec exposure to infrared and green laser.

Potential Therapeutic Strategies for Skeletal Muscle Atrophy

The maintenance of muscle homeostasis is vital for life and health. Skeletal muscle atrophy not only seriously reduces people's quality of life and increases morbidity and mortality, but also causes a huge socioeconomic burden. To date, no effective treatment has been developed for skeletal muscle atrophy owing to an incomplete understanding of its molecular mechanisms. Exercise therapy is the most effective treatment for skeletal muscle atrophy. Unfortunately, it is not suitable for all patients, such as fractured patients and bedridden patients with nerve damage. Therefore, understanding the molecular mechanism of skeletal muscle atrophy is crucial for developing new therapies for skeletal muscle atrophy. In this review, PubMed was systematically screened for articles that appeared in the past 5 years about potential therapeutic strategies for skeletal muscle atrophy. Herein, we summarize the roles of inflammation, oxidative stress, ubiquitin-proteasome system, autophagic-lysosomal pathway, caspases, and calpains in skeletal muscle atrophy and systematically expound the potential drug targets and therapeutic progress against skeletal muscle atrophy. This review focuses on current treatments and strategies for skeletal muscle atrophy, including drug treatment (active substances of traditional Chinese medicine, chemical drugs, antioxidants, enzyme and enzyme inhibitors, hormone drugs, etc.), gene therapy, stem cell and exosome therapy (muscle-derived stem cells, non-myogenic stem cells, and exosomes), cytokine therapy, physical therapy (electroacupuncture, electrical stimulation, optogenetic technology, heat therapy, and low-level laser therapy), nutrition support (protein, essential amino acids, creatine, β-hydroxy-β-methylbutyrate, and vitamin D), and other therapies (biomaterial adjuvant therapy, intestinal microbial regulation, and oxygen supplementation). Considering many treatments have been developed for skeletal muscle atrophy, we propose a combination of proper treatments for individual needs, which may yield better treatment outcomes.

Light Emitting Diodes Photobiomodulation Improves Cardiac Function by Promoting ATP Synthesis in Mice With Heart Failure

Heart failure (HF) is the common consequences of various cardiovascular diseases, often leading to severe cardiac output deficits with a high morbidity and mortality. In recent years, light emitting diodes-based therapy (LEDT) has been widely used in multiple cardiac diseases, while its modulatory effects on cardiac function with HF still remain unclear. Therefore, the objective of this study was to investigate the effects of LED-Red irradiation on cardiac function in mice with HF and to reveal its mechanisms. In this study, we constructed a mouse model of HF. We found that LED-Red (630 nm) was an effective wavelength for the treatment of HF. Meanwhile, the application of LED-Red therapy to treat HF mice improved cardiac function, ameliorate heart morphology, reduced pulmonary edema, as well as inhibited collagen deposition. Moreover, LED-Red therapy attenuated the extent of perivascular fibrosis. Besides, LED-Red irradiation promoted calcium transients in cardiomyocytes as well as upregulated ATP synthesis, which may have positive implications for contractile function in mice with HF. Collectively, we identified that LED-Red exerts beneficial effects on cardiac function in HF mice possibly by promoting the synthesis of ATP.

Effects of Buprenorphine, Chlorhexidine, and Low-level Laser Therapy on Wound Healing in Mice

Systemic buprenorphine and topical antiseptics such as chlorhexidine are frequently used in research animals to aid in pain control and to reduce infection, respectively. These therapeutics are controversial, especially when used in wound healing studies, due to conflicting data suggesting that they delay wound healing. Low-level laser therapy (LLLT) has been used to aid in wound healing without exerting the systemic effects of therapies such as buprenorphine. We conducted 2 studies to investigate the effects of these common treatment modalities on the rate of wound healing in mice. The first study used models of punch biopsy and dermal abrasion to assess whether buprenorphine HCl or 0.12% chlorhexidine delayed wound healing. The second study investigated the effects of sustained-released buprenorphine, 0.05% chlorhexidine, and LLLT on excisional wound healing. The rate of wound healing was assessed by obtaining photographs on days 0, 2, 4, 7, and 9 for the punch biopsy model in study 1, days 0, 1, 2, 4, 6, 8, 11, and 13 for the dermal abrasion model in study 1, and days 0, 3, 6, and 10 for the mice in study 2. Image J software was used to analyze the photographed wounds to determine the wound area. When comparing the wound area on the above days to the original wound area, no significant differences in healing were observed for any of the treatment groups at any time period for either study. Given the results of these studies, we believe that systemic buprenorphine, topical chlorhexidine, and LLLT can be used without impairing or delaying wound healing in mice.

Laser-Induced Differentiation of Human Adipose-Derived Stem Cells to Temporomandibular Joint Disc Cells

BACKGROUND AND OBJECTIVES

Temporomandibular disorder (TMD) is an incapacitating disease with temporomandibular joint (TMJ) disc degenerative changes in patients. Despite several research attempts to find a definitive treatment, there is no evidence of a permanent solution. The objective of the current study was to observe the role of 660 nm diode laser in the differentiation of human adipose-derived stem cells (ADSCs) to fibroblasts and chondrocytes.

STUDY DESIGN/MATERIALS AND METHODS

After irradiation, the morphology, viability, and adenosine triphosphate (ATP) proliferation of the ADSCs were analyzed at different time intervals. The differentiation of ADSCs toward fibroblastic and chondrogenic phenotypes was supported using flow cytometry and immunofluorescence at 1- and 2-week post-irradiation.

RESULTS

More than 90% of viable cells were observed in all experimental groups, with an increase in ATP proliferation. Flow cytometry analyses and immunofluorescence demonstrated the presence of chondrogenic and fibroblastic cell surface markers at 1- and 2-week post-irradiation.

CONCLUSION

This study has demonstrated methods to induce the differentiation of ADSCs toward fibroblastic and chondrogenic phenotypes with a 660 nm diode laser. The study also proposes a future alternative method of treatment for patients with degenerative TMJ disc disorders and presents a positive prospect in the application of photobiomodulation and ADSCs in the treatment of degenerative TMJ disc. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Photobiomodulation Therapy to Mitigate Radiation Fibrosis Syndrome

Objective: We evaluated the role of photobiomodulation (PBM) in radiation fibrosis syndrome (RFS). Background: Radiation therapy (RT) is an important treatment utilized in over half of newly diagnosed cancers. Despite its benefits, patients treated with RT may experience acute and chronic significant side effects depending on both treatment- and patient-related factors. RFS is an important long-term side effect of RT, which can adversely impact patient's quality of life and organ function. With improved oncologic outcomes and survival for cancer patients after radiation, there is an unmet need to address long-term side effects of RT, particularly RFS. Results: Photobiomodulation (PBM) using low energy, nonionizing light primarily in the visible (especially red) or near-infrared spectrum has been demonstrated to decrease acute side effects of radiation in rigorously conducted phase III randomized studies; however, its potential benefit in ameliorating chronic radiation side effects, particularly RFS remains to be investigated. Conclusions: This review summarizes the in vitro data, preclinical animal studies and clinical reports, which showcase the potential benefits of PBM treatments in preventing and reversing RFS.

Monosialoganglioside protects against bupivacaine-induced neurotoxicity caused by endoplasmic reticulum stress in rats

Background

Local anesthetics in spinal anesthesia have neurotoxic effects, resulting in severe neurological complications. Intrathecal monosialoganglioside (GM1) administration has a therapeutic effect on bupivacaine-induced neurotoxicity. The aim of this study was to determine the underlying mechanisms of bupivacaine-induced neurotoxicity and the potential neuroprotective role of GM1.

Materials and methods

A rat spinal cord neurotoxicity model was established by injecting bupivacaine (5%, 0.12 μL/g) intrathecally. The protective effect of GM1 (30 mg/kg) was evaluated by pretreating the animals with it prior to the bupivacaine regimen. The neurological and locomotor functions were assessed using standard tests. The histomorphological changes, neuron degeneration and apoptosis, and endoplasmic reticulum stress (ERS) relevant markers were analyzed using immunofluorescence, quantitative real-time PCR, and Western blotting.

Results

Bupivacaine resulted in significant neurotoxicity in the form of aberrant neurolocomoter functions and spinal cord histomorphology and neuronal apoptosis. Furthermore, the ERS specific markers were significantly upregulated during bupivacaine-induced neurotoxicity. These neurotoxic effects were ameliorated by GM1.

Conclusion

Pretreatment with GM1 protects against bupivacaine-induced neurotoxicity via the inhibition of the GRP78/PERK/eIF2α/ATF4-mediated ERS.

Dexamethasone-induced impairment of post-injury skeletal muscle regeneration

Background

Due to the routine use of dexamethasone (DEX) in veterinary and human medicine and its negative impact on the rate of wound healing and skeletal muscle condition, we decided to investigate the effect of DEX on the inflammatory and repair phases of skeletal muscle regeneration. In this study, a porcine skeletal muscle injury model was used. The animals were divided into non-treated and DEX-treated (0.2 mg/kg/day) groups. On the 15th day of DEX administration, bupivacaine hydrochloride-induced muscle injury was performed, and the animals were sacrificed in subsequent days. Regeneration was assessed by histopathology and immunohistochemistry. In the inflammatory phase, the presence and degree of extravasation, necrosis and inflammation were evaluated, while in the repair phase, the numbers of muscle precursor cells (MPCs), myotubes and young myofibres were estimated.

Results

In the inflammatory phase, DEX increased the severity and prolonged extravasation, prolonged necrosis and inflammation at the site of the muscle injury. In the repair phase, DEX delayed and prolonged MPC presence, impaired and prolonged myotube formation, and delayed young myofibre formation. Furthermore, DEX markedly affected the kinetics of the parameters of the inflammatory phase of the skeletal muscle regeneration more than that of the repair phase.

Conclusions

DEX impairment of the inflammatory and repair phases of the skeletal muscle regeneration was proven for the first time. The drug appears to affect the inflammatory phase more than the repair phase of regeneration. In light of our results, the possibility of reduction of the regenerative capacity of skeletal muscles should be considered during DEX therapy, and its use should be based on risk–benefit assessment.

Therapeutic efficacy of early photobiomodulation therapy on the zones of stasis in burns: An experimental rat model study

This study aimed to investigate the role of photobiomodulation therapy in preventing zones of stasis in burn wounds. We hypothesized that photobiomodulation therapy could promote tissue formation and release of nitric oxide (NO), and reduce inflammatory responses, thereby dilating local microvessels, reducing necrosis and apoptosis. Thirty rats were randomly divided into control group (CG) and laser group (LG). The zone of stasis was formed by applying a brass comb to the skin resulting in four rectangular burns separated by three unburned interspaces. The left side was laser wound (LW), while the right side was shielded wound (SW). The LW of LG was immediately subjected to photobiomodulation therapy, followed by once-daily 30-minutes photobiomodulation therapy sessions. Skin ultrasound and Doppler angiography analyses were used to evaluate the statuses of the zones of stasis at 1, 24, and 96 hours after injury. Harvested burn wound tissue was subjected to hematoxylin-eosin staining and HMGB1, caspase 3, and thrombomodulin immunohistochemistry, and the contents of NO and TNF-α were measured in stasis tissue. Thrombomodulin, HMGB1, and caspase 3 immunohistochemistry revealed significantly lower positive staining rates in the LW of LG rats relative to the others at 96 hours (p < 0.05), as well as a significantly higher skin blood flow relative to the others (p < 0.05). The NO content was significantly higher in the LW of LG, compared with other wounds, at 24 and 96 hours after injury (p < 0.05). The TNF-α level was significantly lower in the LW of LG than in other wounds at 96 hours (p < 0.05). Early, local photobiomodulation therapy can effectively ameliorate injury progression in the zone of stasis. However, these beneficial effects are limited to the directly irradiated sites.

Is there a measure for low power laser dose?

Low power lasers have been used successfully for treatment of many diseases in soft and bone tissues. Basic and clinical researches have developed quickly being the scientific basis to therapeutic protocols based on these lasers. However, there are difficulties to compare experimental and clinical results obtained from different researchers because a complicated and intricate list of physical and biological parameters should be checked before the irradiation procedures as well as part of these parameters are omitted or inaccurately reported. This review focuses on the physical and biological parameters proposed to make experimental and clinical protocols accurate and reproducible as well as suggests dose parameters based on biological effects induced by low power lasers. A variety of parameters are reported by different authors and the number of parameter suggested could overcome three dozens. Thus, laser dose and laser dose equivalent are defined based on laser-induced biological effects and suggested as simplified dose parameters for low power lasers. These parameters could simplify and be useful to researchers and clinicians, permitting comparisons and decreasing mistakes and inaccuracies when laser-induced effects are evaluated and compared with those obtained in previous studies. The laser dose and laser dose equivalent could contribute significantly to improve accuracy, effectiveness, and safety of clinical protocols based on low power lasers.

Photobiomodulation using high- or low-level laser irradiations in patients with lumbar disc degenerative changes: disappointing outcomes and remarks

Background

Laser therapy seems to be a beneficial physical agent for chronic low back pain (LBP), and it is commonly used in the clinical rehabilitation practice. However, there are still no indisputable and clearly defined protocols and practical guidelines, and further, the methodology of the previous reports leaves many unsatisfied and raises some reservations.

Objective

The aim of this study was to evaluate the effectiveness of low-level laser therapy (LLLT) and high-intensity laser therapy (HILT) in patients with lumbar disc degenerative changes based on the analysis of the short- and long-term results and in comparison with the placebo effect.

Design

This study was a prospective and placebo-controlled clinical trial.

Materials and methods

A group of 68 participants were qualified for the therapy and were assigned to four comparative groups in the order they volunteered: HILT of 1,064 nm, 60 J/cm², 10 minutes (HILT); sham (HILT placebo); LLLT of 785 nm, 8 J/cm², 8 minutes; and sham (LLLT placebo). The following tests were used to assess the effectiveness of treatment: 1) the visual analogue scale; 2) the Laitinen Questionnaire Indicators of Pain; 3) the Oswestry Disability Index; 4) the Roland–Morris Disability Questionnaire; 5) Lasegue test; and 6) Schober’s test. All measurements were carried out before and after irradiations (3 weeks) and in follow-ups (1 and 3 months).

Results

After applying verum or placebo laser irradiation, therapeutic progress was observed in all comparative groups; however, no statistically significant differences were observed among the procedures.

Conclusion

The high- and low-energy laser therapy methods used in the present article are ineffective in relation to patients with lumbar disc degenerative changes in both the short- and long-term perspectives and do not show a significant advantage over the placebo effect.

Photobiomodulation Therapy (PBMT) in Peripheral Nerve Regeneration: A Systematic Review

Photobiomodulation therapy (PBMT) has been investigated because of its intimate relationship with tissue recovery processes, such as on peripheral nerve damage. Based on the wide range of benefits that the PBMT has shown and its clinical relevance, the aim of this research was to carry out a systematic review of the last 10 years, ascertaining the influence of the PBMT in the regeneration of injured peripheral nerves. The search was performed in the PubMed/MEDLINE database with the combination of the keywords: low-level laser therapy AND nerve regeneration. Initially, 54 articles were obtained, 26 articles of which were chosen for the study according to the inclusion criteria. In the qualitative aspect, it was observed that PBMT was able to accelerate the process of nerve regeneration, presenting an increase in the number of myelinated fibers and a better lamellar organization of myelin sheath, besides improvement of electrophysiological function, immunoreactivity, high functionality rate, decrease of inflammation, pain, and the facilitation of neural regeneration, release of growth factors, increase of vascular network and collagen. It was concluded that PBMT has beneficial effects on the recovery of nerve lesions, especially when related to a faster regeneration and functional improvement, despite the variety of parameters.

Current Methods for Skeletal Muscle Tissue Repair and Regeneration

Skeletal muscle has the capacity of regeneration after injury. However, for large volumes of muscle loss, this regeneration needs interventional support. Consequently, muscle injury provides an ongoing reconstructive and regenerative challenge in clinical work. To promote muscle repair and regeneration, different strategies have been developed within the last century and especially during the last few decades, including surgical techniques, physical therapy, biomaterials, and muscular tissue engineering as well as cell therapy. Still, there is a great need to develop new methods and materials, which promote skeletal muscle repair and functional regeneration. In this review, we give a comprehensive overview over the epidemiology of muscle tissue loss, highlight current strategies in clinical treatment, and discuss novel methods for muscle regeneration and challenges for their future clinical translation.

High final energy of gallium arsenide laser increases MyoD gene expression during the intermediate phase of muscle regeneration after cryoinjury in rats

The aim of this study was to determine the effects of gallium arsenide (GaAs) laser on IGF-I, MyoD, MAFbx, and TNF-α gene expression during the intermediate phase of muscle regeneration after cryoinjury 21 Wistar rats were divided into three groups (n = 7 per group): untreated with no injury (control group), cryoinjury without GaAs (injured group), and cryoinjury with GaAs (GaAs-injured group). The cryoinjury was induced in the central region of the tibialis anterior muscle (TA). The region injured was irradiated once a day during 14 days using GaAs laser (904 nm; spot size 0.035 cm², output power 50 mW; energy density 69 J cm^-2; exposure time 4 s per point; final energy 4.8 J). Twenty-four hours after the last application, the right and left TA muscles were collected for histological (collagen content) and molecular (gene expression of IGF-I, MyoD, MAFbx, and TNF-α) analyses, respectively. Data were analyzed using one-way ANOVA at P < 0.05. There were no significant (P > 0.05) differences in collagen density and IGF-I gene expression in all experimental groups. There were similar (P < 0.05) decreases in MAFbx and TNF-α gene expression in the injured and GaAs-injured groups, compared to control group. The MyoD gene expression increased (P = 0.008) in the GaAs-injured group, but not in the injured group (P = 0.338), compared to control group. GaAs laser therapy had a positive effect on MyoD gene expression, but not IGF-I, MAFbx, and TNF-α, during intermediary phases (14 days post-injury) of muscle repair.

The influence of low-intensity He-Ne laser on the wound healing in diabetic rats

The low-level laser irradiation at certain wavelengths is reported to facilitate the healing process of diabetic wounds. Thus, this study carried out to look for the suitable laser parameters that could speed up the healing process. Fourteen healthy male and female rats were used in which a circular wound with a diameter of 2.5 ± 0.2 cm was created on the dorsum in each rat after injected them with alloxan to induced diabetic. They have been divided into two groups: control group (N = 7) and study group (N = 7) to conduct the study. He-Ne laser with a wavelength of 632.8 nm at power density of 4.0 mW/cm² was used to irradiate the study group for five times a week until the wound healed (closed) completely, while the control group was kept untreated. The results showed that the laser-treated group healed (wounds were totally closed) faster compared to the control group. In numbers, the laser-treated group healed on average at the 21st day (0.0 ± 0.0 cm) (P ≤ 0.005), whereas the control group healed after 40 days or even 60 days in some cases (sample no. 2). This confirms that laser promotes the tissue repair process of diabetic wounds and reduces the healing period to the half.

High energy Gallium Arsenide laser does not facilitate collagen alteration in muscle skeletal extracellular matrix: experimental study

Abstract Introduction: Low intensity laser therapy has proven effective in treating different tissues, reducing inflammation, preventing the formation of fibrous tissue, and promoting muscle regeneration. Objective: To evaluate the effect of low intensity laser therapy, seven days after the injury, and verify whether the radiated energy chosen influences the formation of fibrous tissue. Methods: Thirty Wistar rats, adult male, average body weight 210-340 g were used. The animals were randomized into three groups: control group, untreated injured group (L), and injured and treated group (LT). After anesthetizing the animals, muscle injury was induced by freezing (cryoinjury) in the central region of the tibialis anterior muscle belly (TA) on the left hind limb, through an iron rod previously immersed in liquid nitrogen. A Gallium Arsenide laser, wavelength 904 nm was used. The applications were initiated 24 hours after injury, daily, for five days, at two points in the lesion area. After 7 days, the animals were euthanized; the TA muscle of the left hind limb was removed and frozen in liquid nitrogen and the obtained histological sections were subjected to Sirius Red staining. Results: Histological analysis showed no significant difference in relation to the area of fibrosis in the LT and L groups. Conclusion: The results suggest that the energy density of 69 J/cm² and final energy (4.8 joules) did not promote alterations in the area of collagen in the skeletal muscle extracellular matrix.