Photobiomodulation therapy protects skeletal muscle and improves muscular function of mdx mice in a dose-dependent manner through modulation of dystrophin

Photobiomodulation Therapy Effects at Different Stages of the Dystrophic Phenotype: A Histomorphometric Study

OBJECTIVE

The purpose of this study was to evaluate the effects of photobiomodulation therapy (PBMT) on the gastrocnemius muscle of X-linked muscular dystrophy (mdx) mice.

METHODS

The study used an experimental model of Duchenne muscular dystrophy, at 3 stages of degeneration/regeneration of muscle fibers: an acute stage (14-28 days old), acute and stabilized stages (14-42 days old), and a stabilized stage (28-42 days old). Photobiomodulation therapy (also known as low-level light therapy) at 0.6 J was applied 3 times per week to the dystrophic gastrocnemius muscle of mdx mice at ages 14 to 28, 14 to 42, and 28 to 42 days. After the treatment period, the gastrocnemius muscle was collected, and cryosections were prepared for histopathologic analysis.

RESULTS

In all 3 stages evaluated, a significant reduction was observed in immunoglobulin G uptake by muscle fibers, the inflammatory area, macrophage infiltration, the reactive dihydroethidium area, and the number of autofluorescent lipofuscin granules in the gastrocnemius muscle of mdx mice after PBMT.

CONCLUSION

The results demonstrated that low-level light therapy, when applied during or after the acute phase of the degeneration/regeneration muscle process, improves the pathological histomorphologic features in dystrophic muscle. Based on these results, PBMT appears to be a promising therapy for dystrophinopathies, warranting further research in humans to verify its efficacy.

Effects of Short-, Medium-, and Long-Term Treatment Using Photobiomodulation Therapy Combined with Static Magnetic Field in Aging Rats

(1) Background: We investigated the detrimental and protective effects of short-, medium, and long-term treatment with different doses of photobiomodulation therapy combined with static magnetic field (PBMT-sMF) during the aging process. (2) Methods: Rats were treated for 15, 30, and 60 weeks with 1, 3, 10, and 30 J of PBMT-sMF or a placebo control. In addition, eight young rats were not subjected to any procedure or treatment and were euthanized at six weeks old. Skin, muscle, bone, kidney, liver, and blood samples were analyzed. (3) Results: No differences between the groups in the morphology of the skin, muscle, and bone was observed. Glutamic pyruvic transaminase levels were increased in the placebo group after 30 and 60 weeks. Glutamic oxaloacetic transaminase levels were also increased in the placebo group after 30 weeks. An increase in creatinine in the PBMT-sMF 3, 10, and 30 J groups compared with that in the young control group was observed. No significant difference in urea levels between the groups was noted. Vascular endothelial growth factor increased in the PBMT-sMF 10 and 30 J groups after 15 weeks of treatment and in the PBMT-sMF 3 J after 60 weeks. Finally, vascular endothelial growth factor decreased in the PBMT-sMF 30 J group after 30 weeks of treatment. (4) Conclusions: PBMT-sMF did not have detrimental effects on the skin, muscle, bone, kidney, or liver after short-, medium-, and long-term treatments in aging rats. In addition, PBMT-sMF may have protective effects on the muscle tissue in aging rats after short- and long-term treatment.

Antioxidant effects of LEDT in dystrophic muscle cells: involvement of PGC-1α and UCP-3 pathways

PURPOSE

Reactive oxygen species and mitochondrial dysfunction play a crucial role in the pathophysiology of Duchenne muscular dystrophy (DMD). The light-emitting diode therapy (LEDT) showed beneficial effects on the dystrophic muscles. However, the mechanisms of this therapy influence the molecular pathways in the dystrophic muscles, particularly related to antioxidant effects, which still needs to be elucidated. The current study provides muscle cell-specific insights into the effect of LEDT, 48 h post-irradiation, on oxidative stress and mitochondrial parameters in the dystrophic primary muscle cells in culture.

METHODS

Dystrophic primary muscle cells were submitted to LEDT, at multiple wavelengths (420 nm, 470 nm, 660 nm and 850 nm), 0.5 J dose, and evaluated after 48 h based on oxidative stress markers, antioxidant enzymatic system and biogenesis, and functional mitochondrial parameters.

RESULTS

The mdx muscle cells treated with LEDT showed a significant reduction of H2O2 production and 4-HNE, catalase, SOD-2, and GR levels. Upregulation of UCP3 was observed with all wavelengths while upregulation of PGC-1α and a slight upregulation of electron transport chain complexes III and V was only observed following 850 nm LEDT. In addition, the mitochondrial membrane potential and mitochondrial mass mostly tended to be increased following LEDT, while parameters like O2·- production tended to be decreased.

CONCLUSION

The data shown here highlight the potential of LEDT as a therapeutic agent for DMD through its antioxidant action by modulating PGC-1α and UCP3 levels.

Multiple LEDT wavelengths modulate the Akt signaling pathways and attenuate pathological events in mdx dystrophic muscle cells

This study is aimed at investigating the effects of LEDT, at multiple wavelengths, on intracellular calcium concentration; on transient receptor potential canonical channels; on calcium-binding protein; on myogenic factors; on myosin heavy chains; on Akt signaling pathway; on inflammatory markers; and on the angiogenic-inducing factor in dystrophic muscle cell culture experimental model. Dystrophic primary muscle cells were submitted to LEDT, at multiple wavelengths (420 nm, 470 nm, 660 nm, and 850 nm), and evaluated after 48 h for cytotoxic effects and intracellular calcium content. TRPC-1, TRPC-6, Calsequestrin, MyoD, Myogenin, MHC-slow, MHC-fast, p-AKT, p-mTOR, p-FoxO1, Myostatin, NF-κB, TNF-α, and VEGF levels were evaluated in dystrophic primary muscle cells by western blotting. The LEDT, at multiple wavelengths, treated-mdx muscle cells showed no cytotoxic effect and significant lower levels in [Ca2 +]i. The mdx muscle cells treated with LEDT showed a significant reduction of TRPC-1, NF-κB, TNF-α and MyoD levels and a significant increase of Myogenin, MHC-slow, p-AKT, p-mTOR, p-FoxO1 levels, and VEGF levels. Our findings suggest that different LEDT wavelengths modulate the Akt-signaling pathways and attenuate pathological events in dystrophic muscle cells, and a combined multiwavelength irradiation protocol may even provide a potentially therapeutic strategy for muscular dystrophies.

Photobiomodulation and Sports: Results of a Narrative Review

Benefits of photobiomodulation (PBM) have been known for several decades. More recently, PBM applied in sports offers a special chance to support the modeling of the performance and recovery. Increasingly complex physical activities and fierce competition in the world of sports generate a state of psycho-emotional and physical stress that can induce chronic fatigue syndrome, failure in physical training, predisposition to muscle damage, physical and emotional exhaustion etc., for which PBM could be an excellent solution. To evaluate and identify all risk factors and the influence of PBM on health and performance in sport and for a better understanding of its effects, we did a search for "Photobiomodulation and Sports" on PubMed, to update the PBM science applied in sports, and we retained for analysis the articles published from 2014 to date. The term "PBM" is recent, and we did not include previous studies with "low level laser therapy" or "LLLT" before 2014. In the present research, PBM has been shown to have valuable protective and ergogenic effects in 25 human studies, being the key to success for high performance and recovery, facts supported also by 22 animal studies. PBM applied creatively and targeted depending on sport and size of the level of physical effort could perfectly modulate the mitochondrial activity and thus lead to remarkable improvements in performance. PBM with no conclusive results or without effects from this review (14 studies from a total of 39 on humans) was analyzed and we found the motivations of the authors from the perspective of multiple causes related to technological limitations, participants, the protocols for physical activity, the devices, techniques and PBM parameters. In the near future, dose-response experiments on physical activity should be designed and correlated with PBM dose-response studies, so that quantification of PBM parameters to allow the energy, metabolic, immune, and neuro-endocrine modulation, perfectly coupled with the level of training. There is an urgent need to continuously improve PBM devices, delivery methods, and protocols in new ingenious future sports trials. Latest innovations and nanotechnologies applied to perform intracellular signaling analysis, while examining extracellular targets, coupled with 3D and 4D sports motion analysis and other high-tech devices, can be a challenge to learn how to maximize PBM efficiency while achieving unprecedented sports performance and thus fulfilling the dream of millions of elite athletes.

Photobiomodulation reduces nociception and edema in a CFA-induced muscle pain model: effects of LLLT and LEDT

Photobiomodulation therapy (PBMT) is an effective therapeutic strategy and a noninvasive method to improve the regulation of inflammation and pain. Our aim was to examine the effects of different doses of PBMT on improvement of edematogenic and nociceptive responses in a myositis model in rats. We administered complete Freund's adjuvant (CFA) into the gastrocnemius muscle (GS) of rats to induce myositis and observe the effect of PBMT using different doses of energy and two types of light sources, a low-level laser (LLL) and light emitting diodes (LED). For this, we evaluated the effects of these different energies to improve nociceptive and edematogenic responses using behavioural tests. In addition, we analysed histological images in animals with myositis induced by CFA. The administration of CFA to the GS induced increased cellular infiltrates, edema and a nociceptive response when compared to animals without myositis. When we treated the CFA-induced myositis animals with PBMT (LLLT or LEDT), we observed a decrease in nociception and edema formation. Our results demonstrated that only the major energy for both the LED and LLL was able to remain in a homogeneous form throughout the period analyzed. Based on our results, we suggest that both LLLT and LEDT using the highest dose (3 J) could be an alternative treatment for myositis in rats.

Can photobiomodulation therapy be an alternative to pharmacological therapies in decreasing the progression of skeletal muscle impairments of mdx mice?

Objective

To compare the effects of photobiomodulation therapy (PBMT) and pharmacological therapy (glucocorticoids and non-steroidal anti-inflammatory drugs) applied alone and in different combinations in mdx mice.

Methods

The animals were randomized and divided into seven experimental groups treated with placebo, PBMT, prednisone, non-steroidal anti-inflammatory drug (NSAIDs), PBMT plus prednisone and PBMT plus NSAID. Wild type animals were used as control. All treatments were performed during 14 consecutive weeks. Muscular morphology, protein expression of dystrophin and functional performance were assessed at the end of the last treatment.

Results

Both treatments with prednisone and PBMT applied alone or combined, were effective in preserving muscular morphology. In addition, the treatments with PBMT (p = 0.0005), PBMT plus prednisone (p = 0.0048) and PBMT plus NSAID (p = 0.0021) increased dystrophin gene expression compared to placebo-control group. However, in the functional performance the PBMT presented better results compared to glucocorticoids (p<0.0001). In contrast, the use of NSAIDs did not appear to add benefits to skeletal muscle tissue in mdx mice.

Conclusion

We believe that the promising and optimistic results about the PBMT in skeletal muscle of mdx mice may in the future contribute to this therapy to be considered a safe alternative for patients with Duchenne Muscular Dystrophy (DMD) in a washout period (between treatment periods with glucocorticoids), allowing them to remain receiving effective and safe treatment in this period, avoiding at this way periods without administration of any treatment.

Insulin resistance is improved in high-fat fed mice by photobiomodulation therapy at 630 nm

Photobiomodulation therapy (PBMT) in the infrared spectrum exerts positive effects on glucose metabolism, but the use of PBMT at the red spectrum has not been assessed. Male Swiss albino mice were divided into low-fat control and high-fat diet (HFD) for 12 weeks and were treated with red (630 nm) PBMT or no treatment (Sham) during weeks 9 to 12. PBMT was delivered at 31.19 J/cm² , 60 J total dose per day for 20 days. In HFD-fed mice, PBMT improved glucose tolerance, insulin resistance and fasting hyperinsulinemia. PBMT also reduced adiposity and inflammatory infiltrate in adipose tissue. Phosphorylation of Akt in epididymal adipose tissue and rectus femoralis muscle was improved by PBMT. In epididymal fat PBMT reversed the reduced phosphorylation of AS160 and the reduced Glut4 content. In addition, PBMT reversed the alterations caused by HFD in rectus femoralis muscle on proteins involved in mitochondrial dynamics and β-oxidation. In conclusion, PBMT at red spectrum improved insulin resistance and glucose metabolism in HFD-fed mice.

Identification of qPCR reference genes suitable for normalizing gene expression in the mdx mouse model of Duchenne muscular dystrophy

The mdx mouse is the most widely-used animal model of the human disease Duchenne muscular dystrophy, and quantitative PCR analysis of gene expression in the muscles of this animal plays a key role in the study of pathogenesis and disease progression and in evaluation of potential therapeutic interventions. Normalization to appropriate stably-expressed reference genes is essential for accurate quantitative measurement, but determination of such genes is challenging: healthy and dystrophic muscles present very different transcriptional environments, further altering with disease progression and muscle use, raising the possibility that no single gene or combination of genes may be stable under all experimental comparative scenarios. Despite the pedigree of this animal model, this problem remains unaddressed. The aim of this work was therefore to comprehensively assess reference gene suitability in the muscles of healthy and dystrophic mice, identifying reference genes appropriate for specific experimental comparisons, and determining whether an essentially universally-applicable set of genes exists. Using a large sample collection comprising multiple muscles (including the tibialis anterior, diaphragm and heart muscles) taken from healthy and mdx mice at three disease-relevant ages, and a panel of sixteen candidate reference genes (FBXO38, FBXW2, MON2, ZFP91, HTATSF1, GAPDH, ACTB, 18S, CDC40, SDHA, RPL13a, CSNK2A2, AP3D1, PAK1IP1, B2M and HPRT1), we used the geNorm, BestKeeper and Normfinder algorithms to identify genes that were stable under multiple possible comparative scenarios. We reveal that no single gene is stable under all conditions, but a normalization factor derived from multiple genes (RPL13a, CSNK2A2, AP3D1 and the widely-used ACTB) appears suitable for normalizing gene expression in both healthy and dystrophic mouse muscle regardless of muscle type or animal age. We further show that other popular reference genes, including GAPDH, are markedly disease- or muscle-type correlated. This study demonstrates the importance of empirical reference gene identification, and should serve as a valuable resource for investigators wishing to study gene expression in mdx mice.

Effect of light-emitting diodes, platelet-rich plasma, and their combination on the activity of sheep tenocytes

Healthy tendons play an important role in joint movements and subjected to a group of pathologies called tendinopathy due to multiple factors. Tendons have a slowly repairing process due to the low vascularity and cellularity. Treatment options aimed at potentiating the healing response and relieving symptoms. Phototherapy and platelet-rich plasma were novel treatment modalities in tendons based on photobiomodulation and growth factors during healing, and the results were encouraging suggesting calibrating treatment parameters. This study utilizes cell culture to explore the potential effect of light-emitting diode and/or growth factors in the form of platelet-rich plasma (PRP) on the activity of tenocytes isolated from sheep Achilles tendons by measuring the cell metabolism and cell mobility using cell viability and migration assays to proof safety and confirm activity. Results showed that sheep tenocyte-cultured groups treated with 5% platelet-rich plasma alone or combined with 4 J/cm² light-emitting diode have increased viability significantly when compared to control group after a 48 h, while light-emitting diode treatment has not decreased cell migration significantly when compared with control. Result suggests that using platelet-rich plasma alone or combined with light-emitting diode might have potential to enhance healing response at the conditions applied. PRP could enhance proliferation while LED could enhance migration and proliferation. Further research is needed at longer durations.

PBMT and topical diclofenac as single and combined treatment on skeletal muscle injury in diabetic rats: effects on biochemical and functional aspects

Physical exercise generates several benefits in a short time in patients with diabetes mellitus. However, it can increase the chances of muscle damage, a serious problem for diabetic patients. Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used to treat these injuries, despite the serious adverse effects. In this way, photobiomodulation therapy (PBMT) with low-level laser therapy (LLLT) and/or light emitting diode therapy (LEDT) can be used as an alternative in this case. However, its efficacy in tissue repair of trauma injuries in diabetes mellitus until now is unknown, as well as the combination between PBMT and NSAIDs. The objective of the present study was to evaluate the effects of NSAIDs and PBMT applied alone or combined on functional and biochemical aspects, in an experimental model of muscle injury through controlled trauma in diabetic rats. Muscle injury was induced by means of a single trauma to the animals' anterior tibialis muscle. After 1 h, the rats were treated with PBMT (830 nm; continuous mode, with a power output of 100 mW; 3.57 W/cm²; 3 J; 107.1 J/cm², 30 s), diclofenac sodium for topical use (1 g), or combination of them. Our results demonstrated that PBMT + diclofenac, and PBMT alone reduced the gene expression of cyclooxygenase-2 (COX-2) at all assessed times as compared to the injury and diclofenac groups (p < 0.05 and p < 0.01 respectively). The diclofenac alone showed reduced levels of COX-2 only in relation to the injury group (p < 0.05). Prostaglandin E₂ levels in blood plasma demonstrated similar results to COX2. In addition, we observed that PBMT + diclofenac and PBMT alone showed significant improvement compared with injury and diclofenac groups in functional analysis at all time points. The results indicate that PBMT alone or in combination with diclofenac reduces levels of inflammatory markers and improves gait of diabetic rats in the acute phase of muscle injury.