Comparative analysis of coherent light action (laser) versus non-coherent light (light-emitting diode) for tissue repair in diabetic rats

The role of light emitting diode in wound healing: A systematic review of experimental studies

Wounds represent a growing global issue demanding increased attention. To expedite wound healing, technologies are under development, and light emitting diode (LED) devices of varying wavelengths are being explored for their stimulating influence on the healing process. This article presents a systematic literature review aiming to compile, organize, and analyze the impacts of LED devices on wound healing. This review is registered on the PROSPERO platform [CRD42023403870]. Two blinded authors conducted searches in the Pubmed, Web of Science, Scopus, Embase, and ScienceDirect databases. In vitro and in vivo experimental studies assessing LED utilization in the wound healing process were included. The search yielded 1010 studies, of which 27 were included in the review. It was identified that LED stimulates different healing pathways, promoting enhanced cell proliferation and migration, angiogenesis stimulation, increased collagen deposition, and modulation of the inflammatory response. Thus, it can be concluded that the LED stimulates cellular and molecular processes contingent on the utilized parameters. The effects depend on the standards used. Cell migration and proliferation were better influenced by green and red LED. The extracellular matrix components and angiogenesis were regulated by all wavelengths and the modulation of inflammation was mediated by green, red, and infrared LEDs.

Exploring the biphasic dose-response effects of photobiomodulation on the viability, migration, and extracellular vesicle secretion of human adipose mesenchymal stem cells

Photobiomodulation (PBM) is a well-established medical technology that employs diverse light sources like lasers or light-emitting diodes to generate diverse photochemical and photophysical reactions in cells, thereby producing beneficial clinical outcomes. In this study, we introduced an 830 nm near-infrared (NIR) laser irradiation system combined with a microscope objective to precisely and controllably investigate the impact of PBM on the migration and viability of human adipose mesenchymal stem cells (hADSCs). We observed a biphasic dose-response in hADSCs' viability and migration after PBM exposure (0-10 J/cm2), with the 5 J/cm2 group showing significantly higher cell viability and migration ability than other groups. Additionally, at the optimal dose of 5 J/cm2, we used nanoparticle tracking analysis (NTA) and found a 6.25-fold increase in the concentration of extracellular vesicles (EVs) derived from hADSCs (PBM/ADSC-EVs) compared to untreated cells (ADSC-EVs). Both PBM/ADSC-EVs and ADSC-EVs remained the same size, with an average diameter of 56 nm measured by the ExoView R200 system, which falls within the typical size range for exosomes. These findings demonstrate that PBM not only improves the viability and migration of hADSCs but also significantly increases the EV yield.

Testing the effects of photobiomodulation on angiogenesis in a newly established CAM burn wound model

Burn wounds are a common challenge for medical professionals. Current burn wound models hold several limitations, including a lack of comparability due to the heterogeneity of wounds and differences in individual wound healing. Hence, there is a need for reproducible in vivo models. In this study, we established a new burn wound model using the chorioallantoic membrane assay (CAM) as a surrogate model for animal experiments. The new experimental setup was tested by investigating the effects of the auspicious biophysical therapy, photobiomodulation (PBM), on the wound healing of an induced CAM burn wound with a metal stamp. PBM has been shown to positively influence wound healing through vascular proliferative effects and the increased secretion of chemotactic substances. The easily accessible burn wounds can be treated with various therapies. The model enables the analysis of ingrowing blood vessels (angiogenesis) and diameter and area of the wounds. The established model was used to test the effects of PBM on burn wound healing. PBM promoted angiogenesis in burn wounds on day 4 (p = 0.005). Furthermore, there was a not significant trend toward a higher number of vessels for day 6 (p = 0.065) in the irradiated group. Changes in diameter (p = 0.129) and the burn area (p = 0.131) were not significant. Our results suggest that CAM can be a suitable model for studying burn wounds. The novel experimental design enables reproducible and comparable studies on burn wound treatment.

Wavelength-Dependent Effects of Photobiomodulation for Wound Care in Diabetic Wounds

Photobiomodulation, showing positive effects on wound healing processes, has been performed mainly with lasers in the red/infrared spectrum. Light of shorter wavelengths can significantly influence biological systems. This study aimed to evaluate and compare the therapeutic effects of pulsed LED light of different wavelengths on wound healing in a diabetic (db/db) mouse excision wound model. LED therapy by Repuls was applied at either 470 nm (blue), 540 nm (green) or 635 nm (red), at 40 mW/cm² each. Wound size and wound perfusion were assessed and correlated to wound temperature and light absorption in the tissue. Red and trend-wise green light positively stimulated wound healing, while blue light was ineffective. Light absorption was wavelength-dependent and was associated with significantly increased wound perfusion as measured by laser Doppler imaging. Shorter wavelengths ranging from green to blue significantly increased wound surface temperature, while red light, which penetrates deeper into tissue, led to a significant increase in core body temperature. In summary, wound treatment with pulsed red or green light resulted in improved wound healing in diabetic mice. Since impeded wound healing in diabetic patients poses an ever-increasing socio-economic problem, LED therapy may be an effective, easily applied and cost-efficient supportive treatment for diabetic wound therapy.

Dual red and near-infrared light-emitting diode irradiation ameliorates LPS-induced otitis media in a rat model

Objective: Otitis media (OM) is an infectious and inflammatory disease of the middle ear (ME) that often recurs and requires long-term antibiotic treatment. Light emitting diode (LED)-based devices have shown therapeutic efficacy in reducing inflammation. This study aimed to investigate the anti-inflammatory effects of red and near-infrared (NIR) LED irradiation on lipopolysaccharide (LPS)-induced OM in rats, human middle ear epithelial cells (HMEECs), and murine macrophage cells (RAW 264.7). Methods: An animal model was established by LPS injection (2.0 mg/mL) into the ME of rats via the tympanic membrane. A red/NIR LED system was used to irradiate the rats (655/842 nm, intensity: 102 mW/m², time: 30 min/day for 3 days and cells (653/842 nm, intensity: 49.4 mW/m², time: 3 h) after LPS exposure. Hematoxylin and eosin staining was performed to examine pathomorphological changes in the tympanic cavity of the ME of the rats. Enzyme-linked immunosorbent assay, immunoblotting, and RT-qPCR analyses were used to determine the mRNA and protein expression levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Mitogen-activated protein kinases (MAPKs) signaling was examined to elucidate the molecular mechanism underlying the reduction of LPS-induced pro-inflammatory cytokines following LED irradiation. Results: The ME mucosal thickness and inflammatory cell deposits were increased by LPS injection, which were reduced by LED irradiation. The protein expression levels of IL-1β, IL-6, and TNF-α were significantly reduced in the LED-irradiated OM group. LED irradiation strongly inhibited the production of LPS-stimulated IL-1β, IL-6, and TNF-α in HMEECs and RAW 264.7 cells without cytotoxicity in vitro. Furthermore, the phosphorylation of ERK, p38, and JNK was inhibited by LED irradiation. Conclusion: This study demonstrated that red/NIR LED irradiation effectively suppressed inflammation caused by OM. Moreover, red/NIR LED irradiation reduced pro-inflammatory cytokine production in HMEECs and RAW 264.7 cells through the blockade of MAPK signaling.

A phase Ⅱ prospective trial of photobiomodulation therapy in limiting oral mucositis in the treatment of locally advanced head and neck cancer patients

Objective

This study aimed to compare the historical incidence rate of severe oral mucositis (OM) in head and neck cancer patients undergoing definitive concurrent chemoradiation therapy (CRT) versus a prospective cohort of patients with locally advanced head and neck squamous cell carcinoma (HNSCC) treated with prophylactic photobiomodulation therapy (PBMT).

Methods

This US-based, institutional, single-arm, phase Ⅱ prospective clinical trial was initiated in 50 patients (age ≥ 18 years, Karnofsky Performance Scale Index > 60, with locally advanced HNSCC (excluding oral cavity) receiving definitive or adjuvant radiation therapy (RT) with concurrent platinum-based chemotherapy (CT). PBMT was delivered three times per week throughout RT utilizing both an intraoral as well extraoral delivery system. Primary outcome measure was incidence of severe OM utilizing both the National Cancer Institute Common Toxicity Criteria, version 4.0 (NCI-CTCAE) Grade ≥3 and the World Health Organization Mucositis Grading Scale (WHO) Grade ≥3 versus historical controls; secondary outcome measures included time to onset of severe OM following therapy initiation.

Results

At baseline, all patients included in final analysis (N = 47) had OM Grade 0. Average RT and CT dose was (66.3 ± 5.1) Gy and (486.1 ± 106.8) mg/m2, respectively. Severe OM was observed in 11 of 47 patients (23%, confidence interval: 12, 38). OM toxicity grade trended upward during treatment, reaching a maximum at 7 weeks (WHO: 1.8 vs. NCI-CTCAE: 1.7). Subsequently, OM grade returned to baseline 3 months following completion of RT. The mean time to onset of severe OM was (35 ± 12) days. The mean time to resolution of severe OM was (37 ± 37) days.

Conclusions

Compared to historical outcomes, PBMT aides in decreasing severe OM in patients with locally advanced HNSCC. PBMT represents a minimally invasive, prophylactic intervention to decrease OM as a major treatment-related side effect.

Effects of photobiomodulation therapy with red LED on inflammatory cells during the healing of skin burns

The aim of this study was to evaluate the effects of red light emitting diode (LED) photobiomodulation therapy protocol on inflammatory cells during the healing of third-degree skin burns. Fifty Wistar rats were randomly divided into control group (CTRL) (n = 25) and red group (RED) (n = 25), with subgroups (n = 5) for each time of euthanasia (7, 14, 21, 28, and 32 days). Treatment animals were daily irradiated (630 nm ± 10 nm, 300 mW, 9 J/cm² per point, 30 s, continuous emission mode) at the 4 angles of the wound (total: 36 J/cm²). After specimen removal, histological sections were stained with hematoxylin and eosin for quantitative analysis of the inflammatory infiltrate (neutrophils and lymphocytes) under light microscopy. Greater number of inflammatory cells was observed in irradiated groups when compared to CTRL at 7, 14, 21, and 28 days, but with statistically significant difference only at 14 days (p = 0.02). At 32 days, higher inflammatory cell value was observed in CTRL when compared to RED, but with no statistically significant difference (p = 0.91). The results suggest that red LED, according to the protocol used, modulates the number of inflammatory cells in the early stages of the healing of third-degree skin burns. Nevertheless, this low-intensity light therapy may not, be efficient in reducing the number of neutrophils and lymphocytes in advanced stages of the repair process of skin burns. Further studies with other therapy protocols are needed to assess the effects of this type of light on the inflammatory response of skin burns.

Effect of Near-Infrared Pulsed Light on the Human Brain Using Electroencephalography

In our previous study, the low-level laser (LLL) stimulation at the palm with a stimulation frequency of 10 Hz was able to induce significant brain activation in normal subjects. The electroencephalography (EEG) changes caused by the stimulation of light-emitting diode (LED) in normal subjects have not been investigated. This study aimed at identifying the effects of LED stimulation on the human brain using EEG analysis. Moreover, the dosage has been raised 4 times than that in the previous LLL study. The LED array stimulator (6 pcs LEDs, central wavelength 850 nm, output power 30 mW, and operating frequency 10 Hz) was used as the stimulation source. The LED stimulation was found to induce significant variation in alpha activity in the occipital, parietal, and temporal regions of the brain. Compared to the previous low-level laser study, LED has similar effects on EEG in alpha (8–12 Hz) activity. Theta (4–7 Hz) power significantly increased in the posterior head region of the brain. The effect lasted for at least 15 minutes after stimulation ceased. Conversely, beta (13–35 Hz) intensity in the right parietal area increased significantly, and a biphasic dose response has been observed in this study.

Enhancing the Therapeutic Potential of Mesenchymal Stem Cells with Light-Emitting Diode: Implications and Molecular Mechanisms

This study evaluated the effects of light-emitting diode (LED) on mesenchymal stem cells (MSCs). An electronic search was conducted in PubMed/MEDLINE, Scopus, and Web of Science database for articles published from 1980 to February 2020. Ten articles met the search criteria and were included in this review. The risk of bias was evaluated to report quality, safety, and environmental standards. MSCs were derived from adipose tissue, bone marrow, dental pulp, gingiva, and umbilical cord. Protocols for cellular irradiation used red and blue light spectrum with variations of the parameters. The LED has been shown to induce greater cellular viability, proliferation, differentiation, and secretion of growth factors. The set of information available leads to proposing a complex signaling cascade for the action of photobiomodulation, including angiogenic factors, singlet oxygen, mitogen-activated protein kinase/extracellular signal-regulated protein kinase, Janus kinase/signal transducer, and reactive oxygen species. In conclusion, although our results suggest that LED can boost MSCs, a nonuniformity in the experimental protocol, bias, and the limited number of studies reduces the power of systematic review. Further research is essential to find the optimal LED irradiation parameters to boost MSCs function and evaluate its impact in the clinical setting.

Antimicrobial Blue Light versus Pathogenic Bacteria: Mechanism, Application in the Food Industry, Hurdle Technologies and Potential Resistance

Blue light primarily exhibits antimicrobial activity through the activation of endogenous photosensitizers, which leads to the formation of reactive oxygen species that attack components of bacterial cells. Current data show that blue light is innocuous on the skin, but may inflict photo-damage to the eyes. Laboratory measurements indicate that antimicrobial blue light has minimal effects on the sensorial and nutritional properties of foods, although future research using human panels is required to ascertain these findings. Food properties also affect the efficacy of antimicrobial blue light, with attenuation or enhancement of the bactericidal activity observed in the presence of absorptive materials (for example, proteins on meats) or photosensitizers (for example, riboflavin in milk), respectively. Blue light can also be coupled with other treatments, such as polyphenols, essential oils and organic acids. While complete resistance to blue light has not been reported, isolated evidence suggests that bacterial tolerance to blue light may occur over time, especially through gene mutations, although at a slower rate than antibiotic resistance. Future studies can aim at characterizing the amount and type of intracellular photosensitizers across bacterial species and at assessing the oxygen-independent mechanism of blue light-for example, the inactivation of spoilage bacteria in vacuum-packed meats.

Phototherapy on Management of Creatine Kinase Activity in General Versus Localized Exercise: A Systematic Review and Meta-Analysis

OBJECTIVE

The main focus of this systematic review was to determine the efficacy of phototherapy in the management of creatine kinase (CK) activity after exercise and furthermore to identify for which exercise model protocol phototherapy provides the best results.

DESIGN

Meta-analysis comparing phototherapy with a control condition.

SETTING

The MEDLINE, EMBASE, SPORTDiscus, PEDro, and CENTRAL databases were searched from their earliest records to October 03, 2016. Data were pooled in a meta-analysis and described as standardized mean difference (SMD) with 95% confidence intervals (CIs) using a random effects model.

PARTICIPANTS

Healthy subjects (no restrictions were applied, eg, age, sex, and exercise level).

INTERVENTION

Phototherapy (low-level laser therapy and/or light-emitting diode therapy) before or after exercise and a placebo or control condition.

MAIN OUTCOME MEASURES

Creatine kinase activity (no restriction to any analysis, eg, serum, plasma, or capillary blood).

RESULTS

Fourteen studies were included for review. The results revealed that phototherapy has a more positive effect than control condition in management of CK activity [SMD = 0.77, 95% CI (0.32 to 1.22); P = 0.0007; I = 72%]. In exploratory analysis, the results showed that phototherapy was effective only in the exercise protocol with localized exercise with large effect size [localized exercise: SMD = 0.89, 95% CI (0.26 to 1.51); P = 0.0002; I = 76%; general exercise: SMD = 0.61, 95% CI (-0.05 to 1.26); P = 0.07; I = 67%].

CONCLUSIONS

The available evidence suggest that phototherapy has beneficial effects on the management of CK activity and demonstrate a possible relationship based on damage caused by exercise, providing a greater effect in studies that used localized exercise.

The strong inhibitory effect of combining anti-cancer drugs AT406 and rocaglamide with blue LED irradiation on colorectal cancer cells

There is still no satisfying method to treat colorectal cancer (CRC) currently. Inspired by cocktail therapy, the combination of 465 nm blue LED irradiation and two multi-target anticancer agents AT406 and Rocaglamide has been investigated as an innovative way to treat colorectal cancer cells in vitro. It showed a strong inhibitory effect on colorectal cancer cells, and its side effects on human normal cells are negligible. When applied to HCT116 cells, it can achieve an apoptotic rate up to 95%. It is also seen to significantly inhibit proliferation of HT29 cells. Furthermore, little to no cell inhibition or damage of normal MRC-5 cells were seen after treatment. The combination of blue LED irradiation and two anti-cancer drugs causes apoptosis of colorectal cancer cells by activating the apoptotic pathway, inhibiting autophagy and proliferation pathways as well as the production of reactive oxygen species (ROS).

Light-triggered release of photocaged therapeutics - Where are we now?

The current available therapeutics face several challenges such as the development of ideal drug delivery systems towards the goal of personalized treatments for patients benefit. The application of light as an exogenous activation mechanism has shown promising outcomes, owning to the spatiotemporal confinement of the treatment in the vicinity of the diseased tissue, which offers many intriguing possibilities. Engineering therapeutics with light responsive moieties have been explored to enhance the bioavailability, and drug efficacy either in vitro or in vivo. The tailor-made character turns the so-called photocaged compounds highly desirable to reduce the side effects of drugs and, therefore, have received wide research attention. Herein, we seek to highlight the potential of photocaged compounds to obtain a clear understanding of the mechanisms behind its use in therapeutic delivery. A deep overview on the progress achieved in the design, fabrication as well as current and possible future applications in therapeutics of photocaged compounds is provided, so that novel formulations for biomedical field can be designed.

Efficacy of Biophysical Energies on Healing of Diabetic Skin Wounds in Cell Studies and Animal Experimental Models: A Systematic Review

We have systematically assessed published cell studies and animal experimental reports on the efficacy of selected biophysical energies (BPEs) in the treatment of diabetic foot ulcers. These BPEs include electrical stimulation (ES), pulsed electromagnetic field (PEMF), extracorporeal shockwave (ECSW), photo energies and ultrasound (US). Databases searched included CINAHL, MEDLINE and PubMed from 1966 to 2018. Studies reviewed include animal and cell studies on treatment with BPEs compared with sham, control or other BPEs. Information regarding the objective measures of tissue healing and data was extracted. Eighty-two studies were eventually selected for the critical appraisal: five on PEMF, four each on ES and ECSW, sixty-six for photo energies, and three about US. Based on the percentage of original wound size affected by the BPEs, both PEMF and low-level laser therapy (LLL) demonstrated a significant clinical benefit compared to the control or sham treatment, whereas the effect of US did not reveal a significance. Our results indicate potential benefits of selected BPEs in diabetic wound management. However, due to the heterogeneity of the current clinical trials, comprehensive studies using well-designed trials are warranted to confirm the results.

Effect of blue LED on the healing process of third-degree skin burns: clinical and histological evaluation

The aim of this study was to evaluate the effects of blue light-emitting diode (LED) on the healing process of third-degree skin burns in rats through clinical and histological parameters. Forty male Wistar rats were divided into two groups: control (CTR) (n = 20) and blue LED (BLUE) (n = 20), with subgroups (n = 5) for each time of euthanasia (7, 14, 21, and 28 days). LED (470 nm, 1 W, 12.5 J/cm² per point, 28 s) was applied at four points of the wound (total, 50 J/cm²). Feed intake was measured every other day. It was observed that there were no statistically significant differences in the Wound Retention Index (WRI) of the BLUE group in relation to CTR group (p > 0.05) at the evaluation times. After 14, 21, and 28 days, it was observed that the animals in the BLUE group consumed more feed than animals in the CTR group (p < 0.05). At 7 days, there was a statistically significant increase in the angiogenic index (AI) in BLUE (median: 6.2) when compared to CTR (median: 2.4) (p = 0.01) and all animals in BLUE had already started re-epithelialization. This study suggests that blue LED, at the dosimetry used, positively contributed in important and initial stages of the healing process of third-degree skin burns.

Photobiomodulation: lasers vs. light emitting diodes?

Photobiomodulation (PBM) is a treatment method based on research findings showing that irradiation with certain wavelengths of red or near-infrared light has been shown to produce a range of physiological effects in cells, tissues, animals and humans. Scientific research into PBM was initially started in the late 1960s by utilizing the newly invented (1960) lasers, and the therapy rapidly became known as "low-level laser therapy". It was mainly used for wound healing and reduction of pain and inflammation. Despite other light sources being available during the first 40 years of PBM research, lasers remained by far the most commonly employed device, and in fact, some authors insisted that lasers were essential to the therapeutic benefit. Collimated, coherent, highly monochromatic beams with the possibility of high power densities were considered preferable. However in recent years, non-coherent light sources such as light-emitting diodes (LEDs) and broad-band lamps have become common. Advantages of LEDs include no laser safety considerations, ease of home use, ability to irradiate a large area of tissue at once, possibility of wearable devices, and much lower cost per mW. LED photobiomodulation is here to stay.

Photobiomodulation: lasers vs. light emitting diodes?

Photobiomodulation (PBM) is a treatment method based on research findings showing that irradiation with certain wavelengths of red or near-infrared light has been shown to produce a range of physiological effects in cells, tissues, animals and humans. Scientific research into PBM was initially started in the late 1960s by utilizing the newly invented (1960) lasers, and the therapy rapidly became known as "low-level laser therapy". It was mainly used for wound healing and reduction of pain and inflammation. Despite other light sources being available during the first 40 years of PBM research, lasers remained by far the most commonly employed device, and in fact, some authors insisted that lasers were essential to the therapeutic benefit. Collimated, coherent, highly monochromatic beams with the possibility of high power densities were considered preferable. However in recent years, non-coherent light sources such as light-emitting diodes (LEDs) and broad-band lamps have become common. Advantages of LEDs include no laser safety considerations, ease of home use, ability to irradiate a large area of tissue at once, possibility of wearable devices, and much lower cost per mW. LED photobiomodulation is here to stay.

LED phototherapy in full-thickness burns induced by CO2 laser in rats skin

Many studies have been conducted on the treatment of burns because they are important in morbidity and mortality. These studies are mainly focused on improving care and quality of life of patients. The aim of this study was evaluate the LED phototherapy effects in rats skin full-thickness burns induced by CO₂ laser. The animals were divided in NT group that did not received any treatment and LED group that received LED irradiation at 685 nm, 220 mW, and 4.5 J/cm² during 40 s by burned area. Biopsies were obtained after 7, 14, and 21 days of treatment and submitted to histological and immunohistochemical analysis. The LED phototherapy shows anti-inflammatory effects, improves angiogenesis, and stimulates the migration and proliferation of fibroblasts. The T CD8+ lymphocytes were more common in burned areas compared to T CD4+ lymphocytes since statistically significant differences were observed in the LED group compared to the NT group after 7 days of treatment. These results showed that LED phototherapy performs positive influence in full-thickness burns repair from the healing process modulated by cellular immune response. The obtained results allowed inferring that burns exhibit a characteristic cell immune response and this cannot be extrapolated to other wounds such as incision and wounds induced by punch, among others.

Light-Emitting Diode treatment ameliorates allergic lung inflammation in experimental model of asthma induced by ovalbumin

Since asthma is a multifactorial disease where treatment sometimes is not effective, new therapies that improve the respiratory discomfort of patients are of great importance. Phototherapy as Light-emitting diode (LED) has emerged as a treatment that presents good results for diseases that are characterized by inflammation. Thus, our objective was to investigate the effects of LED on lung inflammation, by an evaluation of lung cell infiltration, mucus secretion, oedema, and the production of cytokines. Male Balb/c mice were or not sensitized and challenged with ovalbumin (OVA) and treated or not with LED therapy (1 h and 4 h after each OVA challenge). Twenty-four hours after the last OVA challenge, analyzes were performed. Our results showed that LED treatment in asthmatic mice reduced the lung cell infiltration, the mucus production, the oedema, and the tracheal's contractile response. It also increased the IL-10 and the IFN-gamma levels. The effects of LED treatment on lung inflammation may be modulated by IL-10, IFN-gamma, and by mast cells. This study may provide important information about the effects of LED, and in addition, it may open the possibility of a new approach for the treatment of asthma.

Application of phototherapy for the healing of the navels of neonatal dairy calves

The present work evaluated the effects of LED light irradiation on the healing of the navels of neonatal dairy calves. Fifty-seven neonatal calves were divided into two groups. Animals had their umbilical stumps immersed in 10% iodine tincture for 60 s, and this process was repeated every 24 h for three consecutive days. The 29 animals in the first group did not receive LED therapy. The 28 animals in the second group received LED light irradiation at 640 nm with 300 mW power, 46.8 J/cm² energy density, 60 s irradiation time, and 0.385 cm² spot size. The animals were irradiated at four points (46.8 J/cm² per point) evenly distributed around the insertion site of the umbilical stump every 24 h for three consecutive days. Irradiation with LED light was applied before the umbilical stumps were immersed in the iodine solution. The time after birth at which the umbilical stump fell off of each calf was noted. The umbilical stumps of all animals fell off by the 25th day of age. After the umbilical stump fell off, the healing of the remnant wound was followed up to the 30th day after birth. The area of the wound was measured on the 15th, 20th, and 25th day after birth using digital photographs and computer-assisted area measurements. A two-tailed unpaired t test was applied to analyze the falling off the umbilical stump, whereas a Kruskal-Wallis one-way ANOVA test with a Dunn's multiple comparison test was used for the wound size evolution. GraphPad Prisma 5.0® and GraphPad StatMate 2.00® were used for the statistical analysis. The results revealed that phototherapy hastened the falling off the umbilical stump, accelerated navel healing, and reduced the mortality rate in newborn calves. Therefore, this study introduced a preventive and adjuvant after birth treatment that proved to be effective in reducing the incidences of omphalitis and newborn mortality.

Photobiomodulation with LED and laser in repair of mandibular socket rabbit: clinical evaluation, histological, and histomorphometric

PURPOSE

The aim of this study was to evaluate the effects of LED and low-intensity laser on the healing of rabbit dental alveoli.

METHODS

A total of 18 rabbits were divided into three groups of six; all rabbits underwent surgical extraction of the first lower right premolar. Following surgery, group 1 received LED irradiation, group 2 received laser irradiation, and group 3 were untreated controls. The initial applications of LED and laser began 48 h after tooth extraction and were given perpendicularly to the dental alveoli. The three groups were clinically evaluated for 18 days in the postoperative period. At 90 days, the rabbits were euthanized and the mandibular fragments containing the healing alveoli were collected. These fragments initially underwent computed tomography scans and bone density was measured in Hounsfield units. Following this, the fragments were processed and stained with hematoxylin and eosin for histological and histomorphometric analysis.

RESULTS

The results were compatible between the clinical, histological, and histomorphometric parameters evaluated. There were no statistical differences between the LED and laser groups. However, the difference of the average bone density between laser and control group was not statistically significant.

CONCLUSIONS

It was found that photobiomodulation with LASER and LED presented effects. However, only the LED demonstrated a beneficial effect on the process of bone repair in the dental alveoli of rabbits.

Photobiomodulation (Laser and LED) on Sternotomy Healing in Hyperglycemic and Normoglycemic Patients Who Underwent Coronary Bypass Surgery with Internal Mammary Artery Grafts: A Randomized, Double-Blind Study with Follow-Up

BACKGROUND AND OBJECTIVE

This study aimed at analyzing the healing effects of low-level laser therapy (LLLT) (λ620 nm, 6 J/cm²) and light-emitting diode (LED) therapy (λ640 nm, 6 J/cm²) on the longitudinal sternotomy incisions of hyperglycemic and normoglycemic patients who underwent coronary artery bypass grafting (CABG).

MATERIALS AND METHODS

120 volunteers were electively submitted to CABG and were randomly allocated into four different groups of equal size (n = 30): control, placebo, laser (λ of 640 nm and spatial average energy fluency [SAEF] of 1.06 J/cm²), and LED (λ of 660 ± 20 nm and SAEF of 0.24 J/cm²). Laser and LED groups were irradiated from the second to eighth day postsurgery, and sternotomy incision was photographically registered. Then, participants were also separated into hyperglycemic and normoglycemic groups, according to their fasting blood glucose test before surgery. Three researchers blindly analyzed the incision photographs to determine hyperemia and wound closure at the first day of hospital discharge (eighth postoperative day).

RESULTS

LLLT and LED groups had similarly less hyperemia and less incision bleeding or dehiscence (p ≤ 0.005) and the outcomes were also analogous between hyperglycemic and normoglycemic patients, which indicates no difference observed in an intragroup analysis (p ≥ 0.05).

CONCLUSIONS

With the present therapy parameters, it may be assumed that both coherent light (laser) and non-coherent light (LED) are effective in promoting sternotomy and healing acceleration, which are evident on the eighth day postsurgery.

Action of AlGaInP laser and high frequency generator in cutaneous wound healing. A comparative study

PURPOSE

To evaluate in a macroscopic, histological and histomorphometric manner the healing process of cutaneous wounds in mice.

METHODS

The sample consisted of 40 male mice and was divided in four groups: 1st group (control, n=10), 2nd group (High Frequency Generator - HF, the maximum amplitude range, 120s, n=10), 3rd group (AlGaInP Laser 660 nm, 30mW power, 5 J/cm2, applying scan mode, 120s, n=10) and 4thgroup (AlGaInP Laser 660 nm, 30 mW power, 8 J/cm2, applying scan mode, n=10). The surgical incision was made with an 8 mm diameter punch perpendicularly to the back of the animal. The statistical analysis was achieved by the statistical test One Way Anova post hoc Tukey Test and significance at p<0.05 in GraphPad Prism program.

RESULTS

It was observed that in the acute phase the AlGaInP Laser at 5 J/cm2 provided a greater stimulus to healing, and both lasers were effective in the remodeling phase.

CONCLUSION

The AlGaInP lasers from 5 J/cm2 to 8 J/cm2 showed better biomodulatory results in the acute and remodeling phases respectively, however, the HF was less effective than the laser, providing significant benefits only in the acute phase of tissue repair.

Low-Level Laser and Light-Emitting Diode Therapy for Pain Control in Hyperglycemic and Normoglycemic Patients Who Underwent Coronary Bypass Surgery with Internal Mammary Artery Grafts: A Randomized, Double-Blind Study with Follow-Up

OBJECTIVE

This study aimed to evaluate the efficacy of low-level laser therapy (LLLT) and light-emitting diodes (LEDs) for reducing pain in hyperglycemic and normoglycemic patients who underwent coronary artery bypass surgery with internal mammary artery grafts.

METHODS

This study was conducted on 120 volunteers who underwent elective coronary artery bypass graft (CABG) surgery. The volunteers were randomly allocated to four different groups of equal size (n = 30): control, placebo, LLLT [λ = 640 nm and spatial average energy fluence (SAEF) = 1.06 J/cm(2)], and LED (λ = 660 ± 20 nm and SAEF = 0.24 J/cm(2)). Participants were also divided into hyperglycemic and normoglycemic subgroups, according to their fasting blood glucose test result before surgery. The outcome assessed was pain during coughing by a visual analog scale (VAS) and the McGill Pain Questionnaire.

RESULTS

The patients were followed for 1 month after the surgery. The LLLT and LED groups showed a greater decrease in pain, with similar results, as indicated by both the VAS and the McGill questionnaire (p ≤ 0.05), on the 6th and 8th postoperative day compared with the placebo and control groups. The outcomes were also similar between hyperglycemic and normoglycemic patients. One month after the surgery, almost no individual reported pain during coughing.

CONCLUSIONS

LLLT and LED had similar analgesic effects in hyperglycemic and normoglycemic patients, better than placebo and control groups.

Light-emitting diode therapy increases collagen deposition during the repair process of skeletal muscle

This study analyzed the effects of light-emitting diode (LED) therapy on the morphology of muscle tissue as well as collagen remodeling and matrix metalloproteinase 2 (MMP-2) activity in the skeletal muscle of rats following acute injury. Wistar rats were divided into four groups: (1) control, (2) sham, (3) untreated cryoinjury, and (4) cryoinjury treated with LED. Cryoinjury was induced by two applications of a metal probe cooled in liquid nitrogen directly onto the belly of the tibialis anterior muscle. For treatment, the LED equipment (wavelength 850 nm, output power 30 mW, and total energy 3.2 J) was used daily. The study periods were 1, 3, and 7 days after cryoinjury. Morphological aspects were evaluated through hematoxylin-eosin staining. The amount of collagen fibers was evaluated using Picro Sirius Red staining under polarized light. The gelatinase activity of MMP-2 was evaluated using zymography. The results showed significant reductions in inflammatory infiltrate after 3 days and an increased number of immature muscle fibers after 7 days. Furthermore, treatment induced a reduction in the gelatinolytic activity of MMP-2 after 1, 3, and 7 days in comparison to the untreated injury groups and increased the collagen deposition after 3 and 7 days in the treated groups. LED therapy at 850 nm induced a significant reduction in inflammation, decreased MMP-2 activity, and increased the amount of immature muscle and collagen fibers during the muscle repair process following acute injury.

Comparative Study of Morphometric and Fourier Transform Infrared Spectroscopy Analyses of the Collagen Fibers in the Repair Process of Cutaneous Lesions

Objective: Compare the efficacy of light-emitting diode (LED) and therapeutic ultrasound (TUS), combined with a semipermeable dressing (D), at forming collagen in skin lesions by morphometry and Fourier transform infrared spectroscopy (FT-IR). Materials and Methods: Surgical skin wounds (2.5 cm) were created on 84 male Wistar rats divided into four groups (n=21): Group I (Control), Group II (LED), Group III (LED+D), and Group IV (US+D). On days 7, 14, and 21, the tissue samples were removed and divided into two pieces, one was used for histological examination (collagen) and the other for FT-IR. Results: The histomorphometric analysis showed no significant differences among groups for collagen deposition at 7 days. However, at 14 days, more deposition of collagen was noted in the groups LED (p<0.05) and LED+D (p<0.001) than in the control. At 21 days, the groups LED, LED+D, and US+D presented significantly greater deposition of collagen when compared with the control. The FT-IR spectra, at 14 days, LED+D had greater amounts of type I collagen, a better organization of fibers, and greater difference of mean separation between the groups, not observed at 7 and 21 days. Innovation: The histomorphometric and FT-IR analyses suggest that the association of semipermeable dressing to LED therapy and to TUS modulates biological events, increasing fibroblast/collagen response and accelerating dermal maturation. Conclusion: The histomorphometric and FT-IR analyses showed that LED therapy is more efficacious than TUS, when combined with a semipermeable dressing, and induced the collagen production in skin lesions.

Effect of low-level phototherapy on delayed onset muscle soreness: a systematic review and meta-analysis

To determine the effectiveness of low-level phototherapy (i.e. light-emitting diode therapy [LEDtherapy] or light amplification by stimulated emission of radiation therapy [LASERtherapy]) on pain, skeletal muscle injury (creatine kinase [CK] levels and edema) and skeletal muscle function (range of movement and strength) in people undergoing an exercise protocol. (Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PEDro, SciELO and LILACS up to May 2014), we included randomized controlled trials, quasi-randomized controlled trials and crossover studies in which study participants were allocated to receive either low-level phototherapy or placebo treatment. Phototherapy should have been applied in a single treatment session, either before or after an exercise protocol. We identified 15 studies involving 317 participants. Meta-analyses were limited by substantial heterogeneity. Compared to the placebo group, reduction in CK levels was only observed when LASERtherapy was applied before an exercise protocol (standardized mean difference = -0.66; 95 % CI = -1.30, -0.02). No between-group difference in edema, range of movement and strength were detected when phototherapy was applied before or after exercise. Evidence from this review suggests that low-level phototherapy may not have substantial effect in the treatment of skeletal muscle injury and pain caused by exercise. Definitive conclusions are limited due to the small number of included studies in each meta-analysis, disparities across the included studies and small sample sizes.

A comparative study of red and blue light-emitting diodes and low-level laser in regeneration of the transected sciatic nerve after an end to end neurorrhaphy in rabbits

This study aimed at evaluating the effects of red and blue light-emitting diodes (LED) and low-level laser (LLL) on the regeneration of the transected sciatic nerve after an end-to-end neurorrhaphy in rabbits. Forty healthy mature male New Zealand rabbits were randomly assigned into four experimental groups: control, LLL (680 nm), red LED (650 nm), and blue LED (450 nm). All animals underwent the right sciatic nerve neurotmesis injury under general anesthesia and end-to-end anastomosis. The phototherapy was initiated on the first postoperative day and lasted for 14 consecutive days at the same time of the day. On the 30th day post-surgery, the animals whose sciatic nerves were harvested for histopathological analysis were euthanized. The nerves were analyzed and quantified the following findings: Schwann cells, large myelinic axons, and neurons. In the LLL group, as compared to other groups, an increase in the number of all analyzed aspects was observed with significance level (P < 0.05). This finding suggests that postoperative LLL irradiation was able to accelerate and potentialize the peripheral nerve regeneration process in rabbits within 14 days of irradiation.

Activity of Porophyllum ruderale leaf extract and 670-nm InGaP laser during burns repair in rats

BACKGROUND

In this study, we investigated the effects of an extract of the leaves of Porophyllum ruderale and laser irradiation on the healing of burns.

METHODS

Seventy-two rats were divided in four groups: untreated controls, treated with laser irradiation, treated with P. ruderale and treated with both P. ruderale and laser irradiation. Burns were produced with a metal plate on the backs of the animals. Wound samples were collected for structural and morphometric analyses and to quantify the expression of TGF-β1 and VEGF.

RESULTS

Laser irradiation increased the number of fibroblasts, collagen fibers and newly formed vessels and decreased the number of granulocytes at the site of the wounds. Densitometric analysis revealed a significant increase in the expression of TGFβ-1 in the wounds treated with laser irradiation and with the P. ruderale extract at the beginning of the healing process and a decreased during the experimental period. The expression of VEGF was highlighted in the lesions irradiated with laser alone.

CONCLUSION

Inspite of not showing a beneficial effect on the laser combination with the P. ruderale extract, when the laser was used separately, a positive effects to enhance the healing of second-degree burns was promoted. P. ruderale was effective in decreasing the granulocytes during the repair process indicating a possible anti-inflammatory action of this extract of native flora, widely used in folk medicine, but little studied experimentally.

Assessing the biochemical changes of tendons of rats in an experimental model of tenotomy under therapeutic ultrasound and LEDs (625 and 945 nm) by near-infrared Raman spectroscopy

Given the complexity of the tendon repair process, where the neoformed scar tissue tends to prevent or hamper the tendon from performing its normal functions, ultrasound (US) and light-emitting diode (LED) devices have been applied to modulate the tendon repair process. This study aimed to compare the anti-inflammatory and healing effects of therapeutic US and LED in an experimental model of tenotomy using histomorphometry and Raman spectroscopy. Forty Wistar rats (235 ± 8.3 g) were separated into four groups: tenotomy (TC; control), tenotomy associated with ultrasound (US; 1 MHz, 0.5 W/cm(2)), tenotomy associated with LED at 625 nm (LR; 4 J/cm(2)), and tenotomy associated with LED at 945 nm (LIR; 4 J/cm(2)), in two experimental periods of 7 and 14 days. Histomorphometry showed a decrease of inflammatory cells (macrophages and polymorphonuclear leukocytes) for the group treated with US compared to the TC group (ANOVA, p < 0.0001) and the LIR group compared to the TC group (p < 0.05) at the seventh day, indicating an anti-inflammatory effect. In relation to the LR and TC groups, there was no significant difference. Raman spectroscopy revealed that the LR group presented an increased synthesis of collagen I compared to the other treatments and the TC groups on the 14th day (p < 0.01). US therapy showed an adjuvant effect with anti-inflammatory action, and the LED therapy at 625 nm showed an increase in collagen synthesis, contributing to the process of tendon healing.

Effects of low-power light therapy on wound healing: LASER x LED

Several studies demonstrate the benefits of low-power light therapy on wound healing. However, the use of LED as a therapeutic resource remains controversial. There are questions regarding the equality or not of biological effects promoted by LED and LASER. One objective of this review was to determine the biological effects that support the use of LED on wound healing. Another objective was to identify LED´s parameters for the treatment of wounds. The biological effects and parameters of LED will be compared to those of LASER. Literature was obtained from online databases such as Medline, PubMed, Science Direct and Scielo. The search was restricted to studies published in English and Portuguese from 1992 to 2012. Sixty-eight studies in vitro and in animals were analyzed. LED and LASER promote similar biological effects, such as decrease of inflammatory cells, increased fibroblast proliferation, stimulation of angiogenesis, granulation tissue formation and increased synthesis of collagen. The irradiation parameters are also similar between LED and LASER. The biological effects are dependent on irradiation parameters, mainly wavelength and dose. This review elucidates the importance of defining parameters for the use of light devices.

Anti-inflammatory activities of light emitting diode irradiation on collagen-induced arthritis in mice (a secondary publication)

BACKGROUND AND AIMS

Rheumatoid arthritis (RA) is an auto-immune disease afflicting multiple joints of the body, where as a result of the increase in inflammatory cytokines and tissue destructive factors such as matrix metalloproteinase (MMP)-3, deterioration of the bones and cartilages of the joints occurs. The present investigation was carried out to study the anti-inflammatory activities of light emitting diode (LED) irradiation on hind paw inflammation in collagen-induced arthritis (CIA) mice models.

MATERIALS AND METHOD

RA in the CIA mouse model was induced by immunization of DBA/1J mice with intradermal injections of an emulsion of bovine type II collagen and complete Freund's adjuvant. A total of 20 CIA mice were subdivided into the following groups: control group, CIA group and 2 groups of LED irradiated CIA mice (LED groups) (n=5 per group). The mouse knee joint area in the LED groups (the 570 nm and 940 nm groups) was irradiated with LED energy, three times a week for 500 s per session over 8 weeks at a dose of 5 J/cm(2). The hind paw swelling was assessed by the increase in hind paw thickness. The serum levels of the inflammatory cytokines and arthritic factor MMP-3 were determined with an enzyme-linked immunosorbent assay (ELISA).

RESULTS

In the LED-570 and LED-940 groups at 4 weeks after arthritis induction, the swelling inhibition index was 18.1±4.9 and 29.3±4.0 respectively. Interleukin (IL)-1β, IL-6 and MMP-3 serum levels were significantly lower in the LED-940 group.

CONCLUSIONS

LED irradiation, particularly in the near-infrared was effective for inhibition of the inflammatory reactions caused by RA.

Transdentinal cell photobiomodulation using different wavelengths

OBJECTIVE

The aim of this study was to investigate the effects of transdentinal irradiation with different light-emitting diode (LED) parameters on odontoblast-like cells (MDPC-23).

METHODS AND MATERIALS

Human dentin discs (0.2 mm thick) were obtained, and cells were seeded on their pulp surfaces with complete culture medium (Dulbecco modified Eagle medium). Discs were irradiated from the occlusal surfaces with LED at different wavelengths (450, 630, and 840 nm) and energy densities (0, 4, and 25 J/cm(2)). Cell viability (methyltetrazolium assay), alkaline phosphatase activity (ALP), total protein synthesis (TP), and cell morphology (scanning electron microscopy) were evaluated. Gene expression of collagen type I (Col-I) was analyzed by quantitative polymerase chain reaction (PCR). Data were analyzed by the Mann-Whitney test with a 5% significance level.

RESULTS

Higher cell viability (21.8%) occurred when the cells were irradiated with 630 nm LED at 25 J/cm(2). Concerning TP, no statistically significant difference was observed between irradiated and control groups. A significant increase in ALP activity was observed for all tested LED parameters, except for 450 nm at 4 J/cm(2). Quantitative PCR showed a higher expression of Col-I by the cells subjected to infrared LED irradiation at 4 J/cm(2). More attached cells were observed on dentin discs subjected to irradiation at 25 J/cm(2) than at 4 J/cm(2).

CONCLUSION

The infrared LED irradiation at an energy density of 4 J/cm(2) and red LED at an energy density of 25 J/cm(2) were the most effective parameters for transdentinal photobiomodulation of cultured odontoblast-like cells.