Photobiomodulation therapy on collagen type I and III, vascular endothelial growth factor, and metalloproteinase in experimentally induced tendinopathy in aged rats

Effect of combined red and infrared wavelengths on inflammation, hemorrhage, and muscle damage caused by Bothrops leucurus snake venom

To evaluate the effects of red and infrared wavelengths, separately and combined, on the inflammatory process and collagen deposition in muscle damage caused by B. leucurus venom. 112 mice were inoculated with diluted venom (0.6mg/kg) in the gastrocnemius muscle. The animals were divided into four groups: one control (CG) and three treatments, namely: 1) red laser (λ=660 nm) (RG), 2) infrared laser (λ=808 nm) (IG) and 3) red laser (λ=660 nm) + infrared (λ=808 nm) (RIG). Each group was subdivided into four subgroups, according to the duration of treatment application (applications every 24 hours over evaluation times of up to 144 hours). A diode laser was used (0.1 W, CW, 1J/point, ED: 10 J/cm2). Both wavelengths reduced the intensity of inflammation and the combination between them significantly intensified the anti-inflammatory response. Photobiomodulation also changed the type of inflammatory infiltrate observed and RIG had the highest percentage of mononuclear cells in relation to the other groups. Hemorrhage intensity was significantly lower in treated animals and RIG had the highest number of individuals in which this variable was classified as mild. As for collagen deposition, there was a significant increase in RG in relation to CG, in RIG in relation to CG and in RIG in relation to IG. Photobiomodulation proved to be effective in the treatment of inflammation and hemorrhage caused by B. leucurus venom and stimulated collagen deposition. Better results were obtained with the combined wavelengths.

A Novel Tendon Injury Model, Induced by Collagenase Administration Combined with a Thermo-Responsive Hydrogel in Rats, Reproduces the Pathogenesis of Human Degenerative Tendinopathy

Patellar tendinopathy is a common clinical problem, but its underlying pathophysiology remains poorly understood, primarily due to the absence of a representative experimental model. The most widely used method to generate such a model is collagenase injection, although this method possesses limitations. We developed an optimized rat model of patellar tendinopathy via the ultrasound-guided injection of collagenase mixed with a thermo-responsive Pluronic hydrogel into the patellar tendon of sixty male Wistar rats. All analyses were carried out at 3, 7, 14, 30, and 60 days post-injury. We confirmed that our rat model reproduced the pathophysiology observed in human patients through analyses of ultrasonography, histology, immunofluorescence, and biomechanical parameters. Tendons that were injured by the injection of the collagenase-Pluronic mixture exhibited a significant increase in the cross-sectional area (p < 0.01), a high degree of tissue disorganization and hypercellularity, significantly strong neovascularization (p < 0.01), important changes in the levels of types I and III collagen expression, and the organization and presence of intra-tendinous calcifications. Decreases in the maximum rupture force and stiffness were also observed. These results demonstrate that our model replicates the key features observed in human patellar tendinopathy. Collagenase is evenly distributed, as the Pluronic hydrogel prevents its leakage and thus, damage to surrounding tissues. Therefore, this model is valuable for testing new treatments for patellar tendinopathy.

Histological, Physiological and Biomechanical Effects of Low-Level Laser Therapy on Tendon Healing in Animals and Humans: A Systematic Review

Low-level Laser Therapy (LLLT) was widely used in clinical practice for tendon disorders. However, the underlying mechanisms and effectiveness of LLLT in treating tendon injury remain unclear. Therefore, the present study was conducted aiming to summarize the evidence regarding the histological, physiological, and biomechanical effects of LLLT on tendon healing in animal and human models. Four databases were searched for relevant literature. Four independent reviewers screened abstracts and full-text articles, extracted relevant data, evaluated the risk of bias, and quantified the quality of evidence. Database searches yielded 1400 non-duplicated citations. Fifty-five studies were included (50 animal and five human studies). Animal studies revealed that LT had stimulating effects on collagen organization, collagen I and collagen II formation, matrix metalloproteinase (MMP)-8, transforming growth factor β1, vascular endothelial growth factor, hydroxyproline, maximum load, maximum elongation before breaking, and tendon stiffness. However, LLLT had inhibitory effects on the number of inflammatory cells, histological scores, relative amount of collagen III, cyclooxygenase-2, prostaglandin E2 (PGE2), interleukin-6, tumor necrosis factor-α, MMP-1, and MMP-3. Although one human study found that LLLT reduced the concentration of PGE2 in peritendinous tissue of the Achilles tendon, other human studies revealed that the effects of LLLT on the physiology and biomechanics of human tendons remained uncertain. LLLT facilitates tendon healing through various histological, physiological, and biomechanical effects in animal models. Only post-LLLT anti-inflammatory effects were found in human studies.

Effect of Aging on Tendon Biology, Biomechanics and Implications for Treatment Approaches

Tendon aging is associated with an increasing prevalence of tendon injuries and/or chronic tendon diseases, such as tendinopathy, which affects approximately 25% of the adult population. Aged tendons are often characterized by a reduction in the number and functionality of tendon stem/progenitor cells (TSPCs), fragmented or disorganized collagen bundles, and an increased deposition of glycosaminoglycans (GAGs), leading to pain, inflammation, and impaired mobility. Although the exact pathology is unknown, overuse and microtrauma from aging are thought to be major causative factors. Due to the hypovascular and hypocellular nature of the tendon microenvironment, healing of aged tendons and related injuries is difficult using current pain/inflammation and surgical management techniques. Therefore, there is a need for novel therapies, specifically cellular therapy such as cell rejuvenation, due to the decreased regenerative capacity during aging. To augment the therapeutic strategies for treating tendon-aging-associated diseases and injuries, a comprehensive understanding of tendon aging pathology is needed. This review summarizes age-related tendon changes, including cell behaviors, extracellular matrix (ECM) composition, biomechanical properties and healing capacity. Additionally, the impact of conventional treatments (diet, exercise, and surgery) is discussed, and recent advanced strategies (cell rejuvenation) are highlighted to address aged tendon healing. This review underscores the molecular and cellular linkages between aged tendon biomechanical properties and the healing response, and provides an overview of current and novel strategies for treating aged tendons. Understanding the underlying rationale for future basic and translational studies of tendon aging is crucial to the development of advanced therapeutics for tendon regeneration.

Animal model for tendinopathy

Background

Tendinopathy is a common motor system disease that leads to pain and reduced function. Despite its prevalence, our mechanistic understanding is incomplete, leading to limited efficacy of treatment options. Animal models contribute significantly to our understanding of tendinopathy and some therapeutic options. However, the inadequacies of animal models are also evident, largely due to differences in anatomical structure and the complexity of human tendinopathy. Different animal models reproduce different aspects of human tendinopathy and are therefore suitable for different scenarios. This review aims to summarize the existing animal models of tendinopathy and to determine the situations in which each model is appropriate for use, including exploring disease mechanisms and evaluating therapeutic effects.

Methods

We reviewed relevant literature in the PubMed database from January 2000 to December 2022 using the specific terms ((tendinopathy) OR (tendinitis)) AND (model) AND ((mice) OR (rat) OR (rabbit) OR (lapin) OR (dog) OR (canine) OR (sheep) OR (goat) OR (horse) OR (equine) OR (pig) OR (swine) OR (primate)). This review summarized different methods for establishing animal models of tendinopathy and classified them according to the pathogenesis they simulate. We then discussed the advantages and disadvantages of each model, and based on this, identified the situations in which each model was suitable for application.

Results

For studies that aim to study the pathophysiology of tendinopathy, naturally occurring models, treadmill models, subacromial impingement models and metabolic models are ideal. They are closest to the natural process of tendinopathy in humans. For studies that aim to evaluate the efficacy of possible treatments, the selection should be made according to the pathogenesis simulated by the modeling method. Existing tendinopathy models can be classified into six types according to the pathogenesis they simulate: extracellular matrix synthesis-decomposition imbalance, inflammation, oxidative stress, metabolic disorder, traumatism and mechanical load.

Conclusions

The critical factor affecting the translational value of research results is whether the selected model is matched with the research purpose. There is no single optimal model for inducing tendinopathy, and researchers must select the model that is most appropriate for the study they are conducting.

The translational potential of this article

The critical factor affecting the translational value of research results is whether the animal model used is compatible with the research purpose. This paper provides a rationale and practical guide for the establishment and selection of animal models of tendinopathy, which is helpful to improve the clinical transformation ability of existing models and develop new models.

Comparison of the Effects of Open Surgery and Minimally Invasive Surgery on the Achilles Tendon Rupture Healing Based on Angiogenesis

Objective

To compare the effect of three different surgical methods on rabbit Achilles tendon rupture.

Methods

The Achilles tendon transection model was constructed by cutting off the inner half of the Achilles tendon. Rabbits were divided into 4 groups: model group, open surgery (OS) group, minimally invasive surgery (MS) group, and conservative treatment (CT) group. Biomechanical evaluation, H&E, and Picrosirius Red staining were applied to evaluate the histological changes and healing. RT-qPCR, Western blot, ELISA, and IHC staining were used to detect the expression of COLIII, IL-1β, TNF-α, IL-6, CD31, VEGF, bFGF, and TGF-β1.

Results

Different surgery treatments significantly alleviated the histological changes in rabbits. The tension and elasticity of the Achilles tendon were significantly increased after surgery. In addition, surgery treatments notably alleviated the inflammatory responses in vivo via downregulation of IL-1β, TNF-α, and IL-6 and promoted the tube formation in tissues through upregulating VEGF, bFGF, TGF-β1, and CD31. Furthermore, MS exhibited best therapeutic efficiency on Achilles tendon rupture healing, compared with OS or CT.

Conclusions

Our research revealed the superiority of MS in Achilles tendon rupture treatment at the molecular level compared with OS or CT.

Histological tissue healing following high-power laser treatment in a model of suspensory ligament branch injury

BACKGROUND

High-power laser therapy gained popularity recently as a regenerative treatment for tendinitis and desmitis in the horse. However, studies evaluating effects of laser therapy on tissue repair at histological level in large mammals are lacking.

OBJECTIVES

To evaluate effects of high-power laser therapy on suspensory desmitis healing, using a model of suspensory ligament branch injury.

STUDY DESIGN

In vivo experiments.

METHODS

Standardised lesions were surgically induced in all 4 lateral suspensory branches of twelve healthy Warmblood horses. Laser therapy (class 4, 15W) was applied daily on 2 of 4 induced lesions for 4 consecutive weeks. Horses were randomly assigned to either short-term study (horses were sacrificed after 4 weeks) or long-term study (6 months). Suspensory ligament samples were scored after staining with haematoxylin-eosin and immunostaining for collagen 1- collagen 3- and factor VIII.

RESULTS

In the short-term study, significantly better (lower) scores for variation in density (17% above cut-off score in treated lesions vs. 31% above cut-off score in controls, p=0.03), shape of nuclei (54% vs. 92%, p=0.02), fibre alignment (32% vs. 75%, p=0.003) and fibre structure (38% vs. 71%, p=0.02) were found in laser treated lesions when compared to controls. Collagen 3 expression was significantly higher (32% vs. 19%, p=0.006) in control lesions. In both short- and long-term studies combined, parameters lesion size (44% vs. 56%, p=0.02) and shape of nuclei (53% vs. 84%, p=0.05) scored significantly better in treated lesions. Long-term, significantly better (lower) scores were found in the laser-treated group for lesion size (15% vs. 45%, p=0.008) and a higher percentage above cut-off score for density of the nuclei (27% vs. 9%, p=0.02), compared to controls.

MAIN LIMITATIONS

The model of suspensory branch injury is not an exact representation of clinical overstrain lesions.

CONCLUSIONS

These results suggest that high-power laser therapy enables better lesion healing than conservative treatment.

Efficacy of Serial Ultrasonographic Examinations in Predicting Return to Play in Agility Dogs with Shoulder Lameness

The aim of this study is to investigate the use of shoulder ultrasound as a method of predicting the likelihood of returning to competition in agility dogs with shoulder teno-muscular injuries after a standardised rehabilitation protocol. Thirty-two agility dogs with a clinical and ultrasonographic diagnosis of shoulder teno-muscular injury were included in a prospective study with physical and ultrasound examinations at the time of diagnosis (T0) and at two (T2), four (T4) and six (T6) months; during this period, the dogs received rehabilitation treatments. The endpoint of the study was to obtain information regarding participation in agility competitions 12 months after diagnosis, based on telephone interviews with the owners. The clinical lameness score (CLS) and the ultrasound lesion score (ULS) were used as outcome measurements. The CLS indicated partial recovery from a shoulder injury at T2 (78%), while the ULS indicated no satisfactory recovery at T2 in any patient. At 4 months, the CLS alone was not a valuable predictor of full recovery from a shoulder injury in agility dogs. Relative Risk indicated that, at T2, ultrasound was 23.8 times more valuable in identifying a shoulder lesion as compared to clinical lameness score (CLS), and it was 2.53 times more valuable at T4.

Photobiomodulation as an Adjunctive Treatment to Physiotherapy for Reduction of Anterior Knee Pain in Combat Soldiers: A Prospective, Double-Blind, Randomized, Pragmatic, Sham-Controlled Trial

BACKGROUND AND OBJECTIVES

Anterior knee pain (AKP) is the most common knee pathology in athletes and occurs in 15% of army recruits of elite units during basic training. Of these, 50% are symptomatic 6 years later. Photobiomodulation (PBM) is a nonthermal red-to-near-infrared irradiation used for pain reduction of a variety of etiologies. This study was designed to determine whether addition of PBM to physiotherapy (PT) for AKP in combat soldiers is superior to PT alone.

STUDY DESIGN/MATERIALS AND METHODS

In this prospective, double-blind, sham-controlled, randomized clinical trial (NCT02845869), 26 combat soldiers/policemen (male:female, 15:11; body mass index [BMI] = 24.2 ± 3.9, n = 46 knees), with AKP due to overuse/load, received 4 weeks of PT + sham (PT + Sham) or active PBM (wavelength = 660 and 850 nm, pulsing = 2.5 Hz, LED power = 50 mW/cm² [local tissue/regional lymph nodes]; 810 nm continuous beam, laser cluster 6 W/cm² [analgesia] and laser pointer 4.75 W/cm² [trigger points]) (PT + PBM). The main outcome measures were subjective pain by visual analog scale (VAS) (0 [none]-100 [intolerable]) and functional disability by Kujala score (0 [worst]-100 [best]). Evaluations were carried out at baseline, end of treatments, and 3-month follow-up.

RESULTS

All participants completed the treatment protocol without any reported adverse device effects. Post-treatment pain was significantly reduced in the PT+PBM group, compared with baseline and sham (Δpain, VAS, mean ± SD: PT + PBM = -19 ± 23, P = 0.002; PT + Sham = -6 ± 21, P = 0.16; between groups, P = 0.032). At 3-month follow-up, pain reduction was similar between groups; however, the Kujala score was significantly improved only in the PBM-treated group (ΔKujala: PT + PBM = 11 ± 10, P = 0.003; PT + Sham = 5 ± 7, P = 0.059).

CONCLUSIONS

Addition of PBM to PT for AKP resulted in earlier reduction in pain and improved functionality, compared with PT alone. This noninvasive, nonpharmacologic, adjunctive therapeutic modality can be easily incorporated into team healthcare frameworks or end units and may lead to earlier return to competition or combat-level service. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Experimental and Clinical Applications of Red and Near-Infrared Photobiomodulation on Endothelial Dysfunction: A Review

BACKGROUND

Under physiological conditions, endothelial cells are the main regulator of arterial tone homeostasis and vascular growth, sensing and transducing signals between tissue and blood. Disease risk factors can lead to their unbalanced homeostasis, known as endothelial dysfunction. Red and near-infrared light can interact with animal cells and modulate their metabolism upon interaction with mitochondria's cytochromes, which leads to increased oxygen consumption, ATP production and ROS, as well as to regulate NO release and intracellular Ca²⁺ concentration. This medical subject is known as photobiomodulation (PBM). We present a review of the literature on the in vitro and in vivo effects of PBM on endothelial dysfunction.

METHODS

A search strategy was developed consistent with the PRISMA statement. The PubMed, Scopus, Cochrane, and Scholar electronic databases were consulted to search for in vitro and in vivo studies.

RESULTS

Fifty out of >12,000 articles were selected.

CONCLUSIONS

The PBM can modulate endothelial dysfunction, improving inflammation, angiogenesis, and vasodilatation. Among the studies, 808 nm and 18 J (0.2 W, 2.05 cm²) intracoronary irradiation can prevent restenosis as well as 645 nm and 20 J (0.25 W, 2 cm²) can stimulate angiogenesis. PBM can also support hypertension cure. However, more extensive randomised controlled trials are necessary.

Photobiomodulation therapy on expression of HSP70 protein and tissue repair in experimental acute Achilles tendinitis

The aim of the present study was to investigate the effects of photobiomodulation (PBM) therapy on the expression of heat shock protein 70 (HSP70) and tissue repair in an experimental model of collagenase-induced Achilles tendinitis. Thirty Wistar rats (aged 12 weeks) were randomly distributed among control group (n = 8), tendinitis group (n = 11), and LED group (n = 11). Tendinitis was induced in the tendinitis and LED groups through a peritendinous injection of collagenase (100 μl). The LED group animals received the first irradiation 1 h after injury. A 630 ± 20 nm, 300-mW continuous wave light-emitting diode (LED), spot size 1 cm², was placed in contact with the skin. One point over the tendon was irradiated for 30 s, delivering 9 J (9 J/cm²). LED irradiation was performed once daily for 7 days, with the total energy delivered being 63 J. The tendons were surgically removed and expression of the HSP70 protein was calculated using semi-quantitative analyses of immunohistochemistry (HSCORE). Number of fibroblasts and amount of collagen were measured using histological and histochemical analyses. An increase in the mean HSCORE for HSP70, in the number of fibroblasts, and in the amount of collagen were found in the LED group compared with those in the tendinitis and control group (P ≤ 0.05). PBM therapy increased the expression of the HSP70, number of fibroblasts, and amount of collagen in the acute Achilles tendinitis in rats.

Photobiomodulation of Matrix Metalloproteinases in Rat Calcaneal Tendons

Objective: The main objective was to verify the modulatory effects of MMP-1, MMP-3, and MMP-13 levels on the partially injured calcaneal tendons of rat exposure to photobiomodulation. Background: Photobiomodulation has been shown to have anti-inflammatory and regenerative effects on tendon injuries. However, there is still uncertainty regarding the beneficial effects in matrix metalloproteinase (MMP) levels, especially MMP-1, -3, and -13. Materials and methods: Sixty-five male Wistar rats were used. Sixty were submitted to a direct trauma on the calcaneal tendons and were randomly distributed into the following six groups: LASER 1, 3, and 7 (10 partially injured calcaneal tendons in each group treated with photobiomodulation for 1, 3, and 7 days, respectively) and Sham 1, 3, and 7 (same injury, with simulated photobiomodulation). The remaining five animals were allocated to the normal group (no injury or treatment procedure). The 780 nm low-level laser was applied with 70 mW of mean power and 17.5 J/cm² of fluency for 10 sec, once a day. The tendons were surgically removed and analyzed for MMP-1, MMP-3, and MMP-13 through immunohistochemistry. Results: MMP-3 levels remained close to normal in all experimental groups (p > 0.05); however, reductions (p < 0.05) in MMP-1 and MMP-13 levels were detected in the groups submitted to one, three, and seven low level laser therapy applications. Conclusions: The photobiomodulation protocol was able to reduce MMP-1 and MMP-13 levels in injured calcaneal tendons.

Laser Photobiomodulation in the acute inflammatory response of the calcaneal tendon injury in rats exposed to cigarette smoke

ABSTRACT Nicotine delays the healing process and increases the levels of myeloperoxidase (MPO), an enzyme that plays a key role in the production of reactive oxygen species during the inflammatory process. Laser Photobiomodulation (PBM) is one of the most used electrophysical agents in the treatment of the calcaneal tendon, however, its effects on MPO activity need to be further elucidated. This study aimed to evaluate the effects of laser PBM on MPO activity after inflicting an injury to the calcaneal tendon of rats exposed to cigarette smoke. Thirty-four male Wistar rats with 90 days of age were used. After 14 days of exposure to cigarette smoke, the animals were divided into three experimental groups: control group (CG, n=12), not submitted to injury or treatment; sham group (ShG, n=10), submitted to partial calcaneal tendon injury and laser PBM simulation; and laser PBM group (PBMG, n=12), submitted to partial calcaneal tendon lesion and treated with laser PBM within the first minute after injury. PBM decreased MPO activity levels in PBMG compared to ShG (CG: 1.38±0.69pg/ml; ShG: 3.78±1.09pg/ml; PBMG: 2.58±0.93pg/ml; p<0.005). In conclusion, applying laser PBM immediately after inflicting damage to the calcaneal tendon attenuates acute inflammatory activity in rats exposed to cigarette smoke.

Photobiomodulation mechanisms in the kinetics of the wound healing process in rats

OBJECTIVES

The healing process of cutaneous lesions is considered a complex event divided into distinct and overlapping phases, which responds satisfactorily to photobiomodulation (PBM). PBM is indicated as a therapeutic resource capable of assisting tissue repair. The present study aimed to analyze the kinetics of cutaneous wounds healing process after application of the GaAlAs laser for treating wounds on the dorsum of rats.

MATERIALS AND METHODS

This study was approved by the Animal Ethics Committee of UFSCar. The animals were divided into 2 groups (n = 10); control group (CG) used 0.9% saline solution and the laser group (LG) used GaAlAs, 670 nm continuous pulse, 30 mW power, 14.28 J/cm² energy density, irradiating 1 point per wound for 30s, totaling 15 consecutive days of treatment. Samples were collected on the 4th, 11th and 16th days for histological analysis of HE, Picrosirius-Red, immunohistochemistry (Collagen1, TNF-α, VEGF). Statistical analyzes used the one-way ANOVA test for intra and inter group evaluations, and the Tukey post-test. Level of significance was set at p < 0.05.

RESULTS

The histopathological analysis (HE) showed a statistically significant difference for lower values of inflammatory infiltrate in LG versus CG on the 16th day; and for the increase of collagen in the 11th and 16th days of treatment. There was a statistically significant difference in the increase of VEGF on the 11th day for LG; decrease of TNF-α on the 4th and 11th day for LG, and increase of collagen type 1 on the 4th and 16th days for LG. The birefringence analysis of the percentage of collagen fibers presented on the 11th day of treatment revealed a greater quantity and significant statistical difference. Collagen fibers showed improved organization and arrangement on the 11th day for LG.

CONCLUSION

Our results show that PBM is effective in helping the kinetics of the cutaneous wound healing process in rats and promotes the necessary stimuli for the satisfactory evolution of healing process, ultimately leading to structurally desirable tissue.

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.

Could adverse effects and complications of selective laser trabeculoplasty be decreased by low-power laser therapy?

Selective laser trabeculoplasty (SLT) has been used for treatment of primary open-angle glaucoma, ocular hypertension, pigmenter and pseudoexfoliative glaucoma being considered a low-risk procedure. Therefore, transitory and permanent adverse effects have been reported, including corneal changes, subclinical edema, and reduction in endothelial cells and in central corneal thickness. Despite rarer, serious corneal complications after SLT can be permanent and lead to visual impairment, central corneal haze, opacity and narrowing. The mechanism involves increase of vasoactive and chemotactic cytokines causing inflammatory infiltrate, destruction of stromal collagen by fibroblasts and increase of matrix metalloproteinases type 2, which impair reepithelization. SLT also increases free radical production and reduces antioxidant enzymes, resulting in endothelium damages. Low-power laser therapy (LPLT) has been used in regenerative medicine based on its biostimulatory and anti-inflammatory effects. Biostimulation occurs through the interaction of laser photons with cytochrome C oxidase enzyme, which activates intracellular biochemical cascades causing synthesis of a number of molecules related to anti-inflammatory, regenerative effects, pain relief and reduction in edema. It has been showed that LPLT reduces gene expression related to pro-inflammatory cytokines and matrix metalloproteinases, and it increases expression of growth factors related to its proliferative and healing actions. Although radiations emitted by low-power lasers are considered safe and able to induce therapeutic effects, researches based on experimental models for glaucoma could bring important data if LPLT could be an alternative approach to improve acceptation for patients undergoing SLT.