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Effect of NASA Light-Emitting Diode Irradiation on Wound Healing
Abstract
The purpose of this study was to assess the effects of hyperbaric oxygen (HBO) and near-infrared light therapy on wound healing.
Light-emitting diodes (LED), originally developed for NASA plant growth experiments in space show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper, we review and present our new data of LED treatment on cells grown in culture, on ischemic and diabetic wounds in rat models, and on acute and chronic wounds in humans.
In vitro and in vivo (animal and human) studies utilized a variety of LED wavelength, power intensity, and energy density parameters to begin to identify conditions for each biological tissue that are optimal for biostimulation. Results: LED produced in vitro increases of cell growth of 140-200% in mouse-derived fibroblasts, rat-derived osteoblasts, and rat-derived skeletal muscle cells, and increases in growth of 155-171% of normal human epithelial cells. Wound size decreased up to 36% in conjunction with HBO in ischemic rat models. LED produced improvement of greater than 40% in musculoskeletal training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis.
We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program.
... due to their unique characteristics [18,19]. Also, numerous studies have demonstrated that LED-based PBM has a positive effect on the natural process of wound healing [18,26,[33][34][35]. In vitro studies have shown that tissue repair is accelerated and there is an increase in the proliferation of fibroblast cells [35,36], as indicated by some of the studies currently reviewed [24,25,35]. ...
... Also, numerous studies have demonstrated that LED-based PBM has a positive effect on the natural process of wound healing [18,26,[33][34][35]. In vitro studies have shown that tissue repair is accelerated and there is an increase in the proliferation of fibroblast cells [35,36], as indicated by some of the studies currently reviewed [24,25,35]. In addition to reducing wound healing time, in vivo studies have demonstrated that LED-based PBM can significantly reduce pain [28-31, 34, 35]. ...
... Also, numerous studies have demonstrated that LED-based PBM has a positive effect on the natural process of wound healing [18,26,[33][34][35]. In vitro studies have shown that tissue repair is accelerated and there is an increase in the proliferation of fibroblast cells [35,36], as indicated by some of the studies currently reviewed [24,25,35]. In addition to reducing wound healing time, in vivo studies have demonstrated that LED-based PBM can significantly reduce pain [28-31, 34, 35]. ...
Purpose
The aim of the present systematic review was to collect and synthesize the literature concerning the effects of photobiomodulation (PBM) with light-emitting diode (LED) on the prevention and treatment of oral mucositis (OM).
Methods
A systematic review was conducted based on PRISMA 2020 statement. The searches were undertaken in four electronic databases and gray literature, according to the following question: “Is LED-based PBM effective as a preventive and therapeutic treatment for oral mucositis induced by anticancer treatments?”. Inclusion criteria were preclinical studies or clinical trials of LED therapy for subjects with OM induced by antineoplastic treatment.
Results
Eleven studies published between 2002 and 2022 were analyzed. The findings indicate that LED proved to be feasible and safe (3 clinical trials); effective in reducing inflammation (1 pre-clinical), severity (4 pre-clinical and 2 clinical trials), and analgesic and anti-inflammatory prescription requirements (1 clinical trial); in accelerating wound healing (2 pre-clinical and 1 clinical trial); preventing OM (1 pre-clinical and 2 clinical trials); and controlling pain (5 clinical trials). In addition, LED proved to have similar effects to low level laser therapy (LLLT) (2 pre-clinical studies and 2 clinical trials).
Conclusions
The current study adds to our understanding of how PBM with LED could play a significant role in the management of OM and reports promising results of this resource for managing a debilitating complication of cancer therapy.
... The three wavelengths of light that have demonstrated several therapeutic applications are blue (415 nm), red (633 nm), and nearinfrared (830 nm) [1]. Clinical studies demonstrated LEDs had beneficial effects on wound healing [2,3]. Clinical use of photobiomodulation (PBM) therapy, promotes surgical wound closure [4]. ...
... Various PBM parameters have been examined in these studies including wavelengths (ranging from 660 nm to near-infrared 904 nm), pulsing (0-80 Hz) and doses (2-25 J/cm 2 ). Several reviews have published evidence on the effectiveness of PBM treatments in mitigating inflammation and promoting wound healing [2]. Recent studies with blue light (470 nm) showed significant improvement in release of nitric oxide from nitrosyl complexes. ...
... However, infrared illumination activates enzymes and probably also Ca+ channels in the membranes [26]. In vitro studies using infra-/red light have not shown any useful impact on wound healing by activating cells located in deeper skin layers such as fibroblasts or stem cells [2]. ...
The development of light-emitting diodes (LEDs) has led to an increase in the use of lighting regimes within medicine particularly as a treatment for dermatological conditions. New devices have demonstrated significant results for the treatment of medical conditions, including mild-to-moderate acne vulgaris, wound healing, psoriasis, squamous cell carcinoma in situ (Bowen’s disease), basal cell carcinoma, actinic keratosis, and cosmetic applications. The three wavelengths of light that have demonstrated several therapeutic applications are blue (415 nm), red (633 nm), and near-infrared (830 nm). This review shows their potential for treating dermatological conditions. Phototherapy has also been shown to be an effective treatment for allergenic rhinitis in children and adults. In a double-anonymized randomized study it was found that there was 70% improvement of clinical symptoms of allergic rhinitis after intranasal illumination by low-energy narrow-band phototherapy at a wavelength of 660 nm three times a day for 14 consecutive days. Improvement of oedema in many patients with an age range of 7–17 were also observed. These light treatments can now be self-administered by sufferers using devices such as the Allergy Reliever phototherapy device. The device emits visible light (mUV/VIS) and infra-red light (660 nm and 940 nm) wavelengths directly on to the skin in the nasal cavity for a 3 min period. Several phototherapy devices emitting a range of wavelengths have recently become available for use and which give good outcomes for some dermatological conditions.
... Regarding phototherapy, light-emitting diode (LED) studies showed an increase in cell growth in vitro, for example in mouse-derived fibroblasts and normal human epithelial cells, and in vivo wound healing time decreased in crew members aboard a submarine (WHELAN et al., 2001). LED phototherapy with combined 660 and 890 nm lights promoted healing of diabetic ulcers in human patients that had been subject to other treatments without success (MINATEL et al., 2009). ...
... There are several light sources that can be used in PDT and/or phototherapy, including lasers, filtered xenon arc, fluorescent lamps and LEDs (WHELAN et al., 2001;BAROLET, 2008;MORTON et al., 2008;SAMPAIO and LOPES, 2015). In the present cases, red LEDs were used. ...
... Wide-field illumination was important in dogs 1 and 3 that had large area wounds, since the equipment had irradiance of 6 LEDs with 130 mW/ cm². The biological effects of LEDs depend on parameters such as dose, intensity, irradiation time, continuous wave or pulsed mode, and pulse patterns (WHELAN et al., 2001;BAROLET, 2008). ...
The evolution of cutaneous open wounds was evaluated in five client-owned dogs treated with photodynamic therapy (PDT), mediated by methylene blue and phototherapy with light-emitting diodes (LED) as the light source. On the first day of treatment, the wound was irrigated with sterile 0.9% sodium chloride solution, the surface was dried, and 3% solution of hydrogen peroxide soaked for 1 minute. The hydrogen peroxide was mechanically removed and, immediately after, 0.01% methylene blue was used in the wound for five minutes, after which a cluster of red LEDs (650 - 670 nm wavelength, 350 mW power, and irradiance of 200 mW/cm2) was used. Subsequently, single phototherapy sessions, every 48 hours or more, were applied until wound healing. In general, 24J was used for PDT and 12J for phototherapy. In all cases, the cutaneous open wounds treated with PDT associated with phototherapy healed without complications, and it may be considered as a treatment option, especially for extensive lesions.
... HILT generates immediate analgesic and muscle relaxant effects on pulsed emissions and has thermal effect when applied in continuous emission. This is valuable for treating acné [41], scars [42,43,44,45,46] and superficial muscles [47]. There are two useful basic high-intensity laser technologies in the fields of PMR and sports medicine: modified invasive NdYAG laser and highintensity diode laser. ...
... Laser therapy is also useful in other disorders such as temporomandibular degenerative processes [26], shoulder impingement síndrome [32], tendinopathies [17,18,66], fibromyalgia [67], peripheral nerve disorders [12,68,69], and in the healing of wounds [24,41,42,43,44,45,70]. Laser therapy has promising results for the treatment of cold sores [71] and onychomycosis [72,73]. ...
Low-level laser therapy (LLLT) and high-intensity laser therapy (HILT) have emerged as a therapeutic alternative suitable for a wide range of medical conditions. The main advantage of high-intensity laser over LLLT is its ability to deliver a much higher dose in a shorter time while achieving deeper penetration into the affected tissue and producing a thermal effect. Although HILT, provides very satisfactory clinical results, more clinical research is require to justify its massive use. Keywords: Low-level laser therapy, High-level laser therapy, Biostimulation, Phototherapy.
... In addition, LLLT differs from photodynamic therapy, which is based on the effect of light to excite exogenously delivered photosensitizers to produce toxic reactive oxygen species (ROS) [2]. Whelan et al. conducted in vitro and in vivo studies to assess the effects of hyperbaric oxygen and near-infrared (NIR) light therapy on wound healing using various wavelengths, power intensities, and energy density parameters of diode lasers to identify the conditions optimal for biostimulation [3]. These studies found that using diode laser LLLT for light therapy alone or in conjunction with hyperbaric oxygen significantly improves natural wound healing and quickly returns the patient to pre-injury or pre-illness levels. ...
... Furthermore, Whelan et al. conducted in vitro and in vivo studies using a variety of light-emitting diode (LED) wavelength, power intensity, and energy density parameters to identify conditions optimal for biostimulation. In later research, they demonstrated that NIR LED treatment heals poisoned neurons through the stimulation of cytochrome oxidase activity, which protects against retinal damage and improves the retinal function in a rodent model of mitochondrial poison-induced blindness; furthermore, it promotes retinal healing and improves visual function following high-intensity laser-induced retinal injury in adult non-human primates [3][4][5]. Moreover, Desmet et al. studied the use of NIR light treatment in various in vitro and in vivo models to determine the effect of NIR LED light treatment on physiologic and pathologic processes [6]. ...
Our objective was to assess the effect of low-level laser therapy (LLLT) administered using a diode laser on the growth processes of human fibroblast cells involved in wound healing. Initially, studies were conducted using a diode laser at wavelengths of 633, 520, and 450 nm with an irradiance of 3 mW/cm2. The distance between the light source and culture plate was 3 cm. The mechanism(s) of action of the diode laser illumination on human fibroblast cells were studied by examining different wavelengths to determine the relevant light parameters for optimal treatment. In addition, the percentages of fibroblast-mediated procollagen and matrix metallopeptidase (MMP)-1, -2, and -9 production were compared. In the clinical study, the changes in basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and fibroblast collagen production were assessed in 60 patients with complicated wounds who received LLLT (633 nm). No statistically significant difference was observed between red light versus green and blue light in the viability analysis. In addition, the effects of LLLT on the cell cultures of fibroblast cells in vitro demonstrated a decrease in the relative expression of MMP-1, -2, and -9 while using light with a wavelength of 633 nm. In the clinical study, 633 nm diode laser LLLT at 2–8 J/cm2 was administered to 60 patients with complicated wounds; all patients showed increased levels of bFGF and VEGF and the occurrence of collagen synthesis. Our studies demonstrated that LLLT might affect fibroblast cell growth processes involved in wound healing.
... These inconsistencies have led to mixed results and conclusions, underscoring the need for more standardized research protocols. [5][6][7][8][9][10][11][12][13] Moreover, there is a notable lack of comparative studies that specifically evaluate the effects of LLLT and LED therapy on osteoblastic and osteoclastic activities, which are vital processes in bone remodeling and the osseointegration of dental implants. [14][15][16][17][18][19][20][21] Given these gaps in the literature, there is an urgent need for further research to establish standardized PBMT protocols and to thoroughly investigate their efficacy in enhancing the osseointegration and long-term stability of dental implants. ...
Aim: To evaluate and compare the osteogenic potential of two different photobiomodulation therapies—low-level laser therapy (LLLT) and light-emitting diode therapy (LED)—on MG-63 cells cultured on titanium disks.
Materials and methods: A total of 42 titanium disk samples were placed into MG-63 cell-cultured well plates. The samples were divided into three groups: control group, low-level laser diode group (experimental group I), and light-emitting diode group (experimental group II). After the placement of titanium disks, both experimental groups were exposed to their respective radiations for three different durations (2 minutes, 4 minutes, and 6 minutes). Cell viability was evaluated at 24 and 48 hours, while cell growth, attachment, and proliferation were assessed using the MTT assay at 72, 96, and 120 hours.
Results: Both experimental groups demonstrated a positive effect on osteogenic potential. The light-emitting diode group was statistically more significant in promoting osteogenesis compared to the low-level laser diode group and the control group.
Conclusion: LED therapy showed superior osteogenic potential on titanium disks when compared to LLLT. However, further long-term trials on a larger scale are necessary to validate these results.
Clinical significance: This study highlights the potential of LED therapy as a more effective adjunct to dental implant procedures, which could lead to improved osteogenesis and higher success rates in dental implants, especially in challenging clinical conditions.
Keywords: Dental implants, Light emitting diode therapy, Low-level laser therapy, Osteogenesis, Photobiomodulation therapy.
... PBM is emerging as a promising prophylactic and therapeutic approach for managing radiodermatitis. In vivo and in vitro studies indicate that PBM with specific pulse duration and LED fluence positively regulates the synthesis of procollagen and negatively regulates the expression of dermal matrix metalloproteinases, promoting wound healing through antiinflammatory action and reducing apoptosis and cellular necrosis (Weiss et al., 2004;Whelan et al., 2001). The beneficial role of PBM as a supportive modality in treating post-mastectomy lymphedema is well established based on robust evidence (Omar et al., 2012;Smoot et al., 2015), and recent data suggest its efficacy in radiation-induced oral mucositis (Bjordal et al., 2011;Bensadoun et al., 1999). ...
This study reviews the effects of photobiomodulation (PBM) in the prevention of radiodermatitis in breast cancer patients undergoing radiotherapy. Cancer is a major global health challenge and a leading cause of mortality, with approximately 19.3 million new cases reported worldwide in 2020. Breast cancer accounted for 11.6% of these cases and was the second most common cancer in Brazil in 2022, with 2.3 million new cases. Early detection and effective treatments are vital for improving clinical outcomes and patient quality of life. Radiotherapy, commonly used for treating breast cancer, often results in radiation dermatitis (RD), which significantly affects skin health and quality of life. Photobiomodulation (PBM) has emerged as a promising therapy to mitigate radiotherapy’s adverse effects, promoting healing and reducing inflammation. Clinical studies show that PBM can reduce RD severity, enhance skin healing, and relieve pain, with similar benefits observed for radiation-induced oral mucositis. Although preliminary results are promising, further research is needed to optimize PBM protocols and validate its effectiveness as a standard clinical practice. PBM offers a non-invasive and safe approach with potential to significantly improve the management of radiotherapy-related side effects in breast cancer patients.
... Several studies used both sexes [74,75] , while several others used only females [76,77] . Various studies did not state the sexes of their rats [40,78] . Also few articles provided rationales for their selections of strains or sexes of rats used. ...
Wound is defined as the loss of breaking cellular and functional continuity of the living tissues and management of wounds is frequently encountered with different problems. Drug resistance and toxicity hindered the development of synthetic antimicrobial agents with wound healing activity. Many factors should be considered before selecting a wound healing model for a specific study. A wide variety of models have been developed for examining different aspects of the repair response thus many animal models are used for the evaluation of wound healing activities. Rats and mice have been widely used in the study of skin wound healing and efficacy of different treatment modalities. These particular species are mostly selected because of its availability, low cost and small size. In this review, we discussed about the wound and types of wound models that can be used along with the topics like wound location, where it is feasible to create the wound, wound size, strain and sex of rat, weight and age range as well as anaesthetics and analgesics and analytical measures that are used in wound healing studies. The present review will be helpful for the evaluation of drugs having potential for wound healing activity.
... Notably, photobiomodulation therapy, including the use of LED, has garnered significant attention, particularly for its potential in promoting wound healing [7,14,30,31]. Our investigation revealed that our device employing multispectral wavelengths exhibited a favorable impact on both epidermal thickness and the basement membrane, aligning with findings from prior research [32][33][34][35]. This treatment was also recognized for its capacity to augment collagen generation within the skin while concurrently suppressing the synthesis of matrix metalloproteinase [36]. ...
Purpose
The management of pressure ulcers (PUs) poses challenges due to their chronic nature and the lack of established conservative treatment methods. In this clinical trial, our objective was to examine the validity and safety of using a light-emitting diode device contained four wavelengths in the treatment of grade 2 sacral PUs.
Method
A total of 38 patients were randomly assigned to two groups: sham device (Sham) and experimental device (LED) group. The treatment sessions were conducted over a period of four weeks, with a frequency of three times per week. The study was conducted in a double-blinded manner. The study assessed the primary validity by measuring wound size and re-epithelialization after 0 and 4 weeks. Secondary evaluations included epidermal regeneration, collagen density, and immunological markers. Safety was evaluated by monitoring adverse reactions throughout the trial.
Result
The presence of eschar was found to have a significant impact on wound healing. Sham consisted of 15 wounds without eschar, while LED had nine. After treatment in without eschar situation, the post-treatment size of wounds in Sham was 13.80 ± 20.29%, while it was 3.52 ± 6.68% in LED. However, there was no significant difference (p = 0.070). And analysis of epidermal thickness showed a significant increase in LED (495.62 ± 327.09 μm) compared to Sham (195.36 ± 263.04 μm) (p < 0.0001).
Conclusion
While LED treatment had a potential for wound reduction in PUs without eschar, we could not uncover evidence to support the efficacy of LED treatment in grade 2 PUs.
... Since the 1960s, studies on the biological effects of light have been reported [11]. In the 1990s, NASA confirmed the skin treatment effects of Near-Infrared (NIR) light, leading to the commercialization of skin regeneration devices utilizing infrared radiation [12]. This effect became widely known as Low-Level Laser Therapy (LLLT) or Photobiomodulation (PBM). ...
The study aimed to explore the impact of a novel near-infrared LED (nNIR) with an extended spectrum on skin enhancement and hair growth. Various LED sources, including White and nNIRs, were compared across multiple parameters: cytotoxicity, adenosine triphosphate (ATP) synthesis, reactive oxygen species (ROS) reduction, skin thickness, collagen synthesis, collagenase expression, and hair follicle growth. Experiments were conducted on human skin cells and animal models. Cytotoxicity, ATP synthesis, and ROS reduction were evaluated in human skin cells exposed to nNIRs and Whites. LED irradiation effects were also studied on a UV-induced photoaging mouse model, analyzing skin thickness, collagen synthesis, and collagenase expression. Hair growth promotion was examined as well. Results revealed both White and nNIR were non-cytotoxic to human skin cells. nNIR enhanced ATP and collagen synthesis while reducing ROS levels, outperforming the commonly used 2chip LEDs. In the UV-induced photoaging mouse model, nNIR irradiation led to reduced skin thickness, increased collagen synthesis, and lowered collagenase expression. Additionally, nNIR irradiation stimulated hair growth, augmented skin thickness, and increased hair follicle count. In conclusion, the study highlighted positive effects of White and nNIR irradiation on skin and hair growth. However, nNIR exhibited superior outcomes compared to White. Its advancements in ATP content, collagen synthesis, collagenase inhibition, and hair growth promotion imply increased ATP synthesis activity. These findings underscore nNIR therapy’s potential as an innovative and effective approach for enhancing skin and promoting hair growth.
... Previous studies showed that LED and lasers at the same wavelengths have similar histological effects such as angiogenesis, collagen stimulation, tissue repair, and analgesia. [51][52][53] It seems that there is a recent trend to use LED as a low-cost and safe alternative to laser systems. Added to this is the ease of home use and the ability to irradiate a large area of tissue at once. ...
Background: Given the suffering experienced by cancer patients, effective solutions must be found to prevent the most painful and debilitating side effects of anticancer treatment. The use of photobiomodulation (PBM) with specific parameters has been proposed to prevent oral mucositis in adults undergoing hematopoietic stem cell transplantation as well as in head and neck cancer patients receiving radiotherapy alone without chemotherapy. No recommendations were possible for patients undergoing chemotherapy alone. This systematic review aims to analyze the effectiveness of preconditioning by PBM in preventing chemotherapy-induced oral mucositis.
Methods: This study was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, PRISMA, Checklist and registered at the International Prospective Register of Systematic Reviews (PROSPERO). We searched and identified articles of the subsequent bibliographic databases: PubMed and Cochrane. Revised Cochrane risk-of-bias tool for randomized trials (RoB 2.0) was used to assess the risk of bias of studies included in this review.
Results: There were only six clinical trials examining the efficacy of PBM therapy in the primary prevention of chemotherapy-induced oral mucositis. All of the studies used lasers, except for one study that compared lasers with light-emitting diodes. The wavelength ranges from 630 to 830 nm. Irradiation parameters varied among the included studies. All studies showed good results for the use of PBM in the prevention of oral mucositis except for one study that found no benefit for the laser application.
Conclusions: PBM has been shown to be effective in preventing oral mucositis when applied to healthy tissues. Finding the optimal protocol has been difficult due to the variability between studies, and therefore, further well-designed, controlled, blinded studies are recommended to precisely determine irradiation parameters and the number of sessions. This review has been registered at the International Prospective Register of Systematic Reviews (PROSPERO) under number CRD42023397771
... Early LEDs produced low and unstable light with a broad wavelength until the National Aeronautics and Space Administration developed a quasimonochromatic LED that produces a very narrow spectrum of light and has a significant effect on wound healing. 1,2 At present, the evolution of LED technology has produced devices that emit light at wavelengths ranging from ultraviolet to near-infrared (247-1300 nm). 3 The variety of wavelengths produced by LEDs has allowed for the expansion of its clinical applications and LEDs have been effective in both therapeutic and aesthetic fields. Blue LED light (400-470 nm), which penetrates up to 1 mm of skin, has been proven to treat skin conditions such as acne, actinic keratosis, and psoriasis. ...
Light-emitting diode (LED) lights produce a variety of wavelengths that have demonstrable efficacy in therapeutic and aesthetic fields. However, a repetitive treatment regimen is required to produce treatment outcomes, which has created a need for portable LED devices. In this study, we aimed to develop a portable therapeutic LED device and investigate its healing effect on excisional wounds in a rat model. The 35 × 35 mm-sized LED device was used on a total of 30 rats with full-thickness wounds that were divided into two groups depending on radiation intensity (11.1 and 22.2 mW/cm2 group). LED irradiation was performed every 24 h for 30 min, over 14 days, in direct contact with the wound. Percentage wound closure was measured by photographic quantification and was assessed histologically using haematoxylin and eosin (H&E) and Masson's Trichrome staining, and immunohistochemistry for Vascular endothelial growth factor (VEGF) and CD31. Percentage wound closure was significantly higher in 22.2 mW/cm2 irradiated wounds than that in the control wounds on days 7 and 10. The area of collagen deposition was remarkably larger in 22.2 mW/cm2 irradiated wounds than that in the control, with more horizontally organized fibres. CD31 immunostaining confirmed a significant increase in the number of microvessels in 22.2 mW/cm2 irradiated wounds than that in the control wounds, although there was no difference in VEGF immunostaining. Our novel portable LED device accelerates wound healing in a rat model, raising the possibility that portable LED devices can combine convenience with accessibility to play an innovative role in wound dressing.
... The semiconductor lasers used in medical applications have the advantage of penetrating biological tissues to great depths when operated in the near-infrared region of wavelengths from 700 to 900 nm, and thus, semiconductor lasers are often used in LLLT research. However, studies examining the effects of LED light on wound healing promotion and cell proliferation indicate potential usefulness in the treatment of stomatitis, a secondary complication in head and neck cancer radiation/chemotherapy patients, and in treating oral mucositis symptoms caused by graft-versus-host disease, which can occur after hematopoietic stem cell transplantation [18][19][20] . It has been reported that in addition to laser light, the beneficial effects of photomedicine can be obtained using a variety of other light sources, such as LED light 8) . ...
Recently, low level laser therapy (LLLT) has been reported to promote wound healing of fractures, tooth extraction sockets and bone-dental implants osseointegration. In this study, we investigated the effects of LLLT on cell proliferation, differentiation and calcification of rat bone marrow-derived osteoblast-like cells using blue LED light irradiation at a wavelength of 455 nm. The irradiation conditions were as follows; LED with a wavelength of 455 nm, 510 mW output power (measured value in the irradiated field: 100 mW/cm²), distance: 20.8 mm, and irradiation for 14 seconds every 1.5 hours at an energy of 5.6 joules/cm² (up to 4.5 hours). The experimental groups were divided into 4 groups; control group, LED light-irradiation group, FGF-containing media group and LED light-irradiation and FGF-containing media group (n=3). The cell proliferative ability was determined using Cell Counting Kit-8 immediately after the first LED irradiation, after 1.5, 3.0, 4.5 and 12 hours by ELISA. Lab assay ALP was used to search for cell differentiation potential, and ALP activity levels in the samples were determined after 3 and 7 days. And the ALP staining was also performed after 7 days, and the ALP staining positive was determined by analyzing the percentage of stained area in each well. For the search of cellular calcification activity, Alizarin Red staining was used to determine its positivity rate by analyzing the stained area fraction of each well after 14 and 28 days. In all the searched results, both the cell proliferation and differentiation abilities were highest in the LED group. And the calcification ability was significantly higher in the LED, FGF and LED▪FGF groups than that in the control group. The results of this study suggested that LLLT with blue LED light irradiation was useful for bone tissue regeneration.
... The wound in the animal bodies specially Cutaneous wound most common wound, and wound healing that depend on many factors, and delay wound promote neo-collagensis, in present study was showed early wound healing compare with control group and collagen group (24,25,26). The combination two therapies at one time in third group (collagen-laser ) therapy , in this idea combine the characteristics therapy of collagen and laser therapies, the effect of Gentamicin in wound healing didn't accelerate but to kill the bacteria or inhibit bacteria in infected wound had inhibition properties to process of wound healing (27). ...
The present study used 24 adult rabbits divided into 4 group, each group had 6 rabbits, all group were incised on dorsal surface (rabbits back), first group were treated by Gentamicin cream as a control group while second group were treated by collagen cream, third group were treated by laser therapy while fourth group were treated by collagen-laser therapy. 2 nd and 3 rd groups were showed significant results compare with 1 st group while 4 th group also excellent significant result, this method can applicant safely and simply and can applicant with other injury .
... NASA have previously reported on accelerated wound healing in singular atmospheric conditions and submarine conditions using PBMT. 3 The reason for the tissue response to PBMT is the energy absorption by certain photo-accepting molecules. Various molecules have been considered to play this role, including melanin, water, as well as chromophores in microorganisms present on the skin. ...
Background
This case-report explores the effects of photobiomodulation therapy (PBMT) on the healing of scar tissue. The patient was a 32-year old female two years post cholecystectomy resulting in a 15 cm linear scar that was causing severe pain.
Methods
Treatment was initiated using the BIOFLEX® therapist device which consists of LED arrays and laser probes of a specific wavelength, power and frequency applied directly on the skin overlying the scar. The frequency and duration of treatment was every other day for six weeks in a clinic setting, followed by three times a week for two months at home. Then the patient continued to use the BIOFLEX® therapist home device on an as-needed basis.
Findings
The final result of this patient's treatment was significant flattening and decreased redness of her scar. Her self-reported pain decreased to a 6/10. At the one year follow up, the patient reported that she stopped taking her opioids, antidepressant and sleeping pills and that her pain decreased to a 4/10. At the last review her pain score was 1/10; and she had returned to work and took Tylenol (acetaminophen) occasionally for breakthrough pain.
Conclusions
We attribute the patient's improvement in scar appearance and pain symptoms to PBMT. Since pain is often associated with depressed mood and sleep disturbances, it cannot be determined whether PBMT was the direct or indirect cause of this patient's improved mood. For future studies, we propose the use of control subjects with similar scars treated with sham treatment compared to those who will receive the PBMT and observed for the same duration of time and compare the overall results.
Lay Summary
Dermatological applications, especially wound healing; are accepted indications for photobiomodulation therapy (PBMT). The expansion into other clinical applications, particularly neurological ones show potential benefit. We present a case of a patient with a hypertrophic scar associated with severe neuropathic pain and concurrent depression, all of which improved directly or indirectly with PBMT. Although the original focus of treatment was dermatological the improvement in pain plus the discontinuation of therapy (opioids, antidepressants and benzodiazepines) were considered to be due to the PBMT.
... LEDs can increase ATP production, mitochondrial membrane potential and the activity of cytochrome C oxidase in melanoma cells, thereby promoting cell proliferation [20]. In addition, LEDs have shown the capability to promote skin activation and wound healing [21,22]. LED-based PBM has also been widely reported in the modulation of neurological disorders, including Alzheimer's and Parkinson's diseases [23,24]. ...
Mammalian cardiomyocytes (CMs) maintain a low capacity for self-renewal in adulthood, therefore the induction of CMs cycle re-entry is an important approach to promote myocardial repair after injury. Recently, photobiomodulation (PBM) has been used to manipulate physiological activities of various tissues and organs by non-invasive means. Here, we demonstrate that conditioned PBM using light-emitting diodes with a wavelength of 630 nm (LED-Red) was capable of promoting the proliferation of neonatal CMs. Further studies showed that low-power LED-Red affected the expression of miR-877-3p and promoted the proliferation of CMs. In contrast, silencing of miR-877-3p partially abolished the pro-proliferative actions of LED-Red irradiation on CMs. Mechanistically, GADD45g was identified as a downstream target gene of miR-877-3p. Conditioned LED-Red irradiation also inhibited the expression of GADD45g in neonatal CMs. Moreover, GADD45g siRNA reversed the positive effect of LED-Red on the proliferation of neonatal CMs. Taken together, conditioned LED-Red irradiation increased miR-877-3p expression and promoted the proliferation of neonatal CMs by targeting GADD45g. This finding provides a new insight into the role of LED-Red irradiation in neonatal CMs biology and suggests its potential application in myocardial injury repair.
... Photobiomodulation (PBM), also known as low-level light therapy (LLLT), has been studied and used for over 50 years (19)(20)(21)(22)(23)(24)(25)(26) to protect cells from dying (22,24,(27)(28)(29)(30) and to target and treat inflammation in organs (31,32). It consists of the application of a narrow spectral bandwidth light from red to near-infrared light (600-1000 nm wavelength) with a power density of 1-5000 mW/ cm 2 to modulate cell metabolism, signal transduction, and secretion in the body (33)(34)(35). ...
Background
Because the major event in COVID-19 is the release of pre- and inflammatory cytokines, finding a reliable therapeutic strategy to inhibit this release, help patients manage organ damage and avoid ICU admission or severe disease progression is of paramount importance. Photobiomodulation (PBM), based on numerous studies, may help in this regard, and the present study sought to evaluate the effects of said technology on cytokine reduction.
Methods
This study was conducted in the 2nd half of 2021. The current study included 52 mild-to-moderately ill COVID-19, hospitalized patients. They were divided in two groups: a Placebo group and a PBM group, treated with PBM (620-635 nm light via 8 LEDs that provide an energy density of 45.40 J/cm² and a power density of 0.12 W/cm²), twice daily for three days, along with classical approved treatment. 28 patients were in Placebo group and 24 in PBM group. In both groups, blood samples were taken four times in three days and serum IL-6, IL-8, IL-10, and TNF-α levels were determined.
Results
During the study period, in PBM group, there was a significant decrease in serum levels of IL-6 (-82.5% +/- 4, P<0.001), IL-8 (-54.4% ± 8, P<0.001), and TNF-α (-82.4% ± 8, P<0.001), although we did not detect a significant change in IL-10 during the study. The IL-6/IL-10 Ratio also improved in PBM group. The Placebo group showed no decrease or even an increase in these parameters. There were no reported complications or sequelae due to PBM therapy throughout the study.
Conclusion
The major cytokines in COVID-19 pathophysiology, including IL-6, IL-8, and TNF-α, responded positively to PBM therapy and opened a new window for inhibiting and managing a cytokine storm within only 3-10 days.
... Green light (peaked at 560 nm) is thought to have a positive effect on the migratory movement of stem cells [23]. And red light (peaked at 630 nm) is mostly used for tissue wound healing, skin inflammation and arthritis treatment [24][25][26][27]. Red light induces differential alterations in 76 genes in wounds treatment [28]. ...
Photobiomodulation (PBM) has emerged as an alternative therapy involved in modulating a variety of biological effects. In this study, we verified whether PBM can affect cardiac physiological activity in mice through noninvasive irradiation using light-emitting diodes at a wavelength of 630 nm (LED-Red). We found that the PBM involved in regulating the repair of injured myocardium is wavelength-limited. LED-Red caused cardiomyocytes (CMs) that had exited the cell cycle to divide and proliferate again, and the cell proliferation ratio increased significantly with the accumulation of intracellular photopower. In addition, LED-Red promoted myocardial revascularization and myocardial regeneration, reduced the area of fibrosis in mice with myocardial infarction (MI), and thus improved cardiac contractile function. In regard to the mechanism, miRNA sequencing analysis showed that low-power LED-Red irradiation could induce differential changes in miRNAs in CMs. Among them, miR-136-5p was identified as a cardiac photo-sensitive miRNA and was obviously inhibited after stimulation, which produced a proliferation-promoting effect on CMs. Subsequent luciferase reporter assays confirmed the involvement of Ino80 as a binding target of miR-136-5p in the regulatory process of CM proliferation. Similarly, LED-Red irradiation elevated intracellular Ino80 expression. After knockdown of Ino80, the proliferation-promoting effect of LED-Red on CMs was inhibited. Collectively, this study demonstrates that LED-Red can promote CM proliferation by inhibiting cardiac photo-sensitive miRNA- miR-136-5p expression through targeting Ino80. The findings provided a new potential strategy for the treatment of ischemic cardiomyopathy (ICD).
... FR/NIR light is produced from a laser or a lightemitting diode (LED), and its therapeutic qualities have been confirmed [121]. FR/NIR light therapy has been widely used over the years, including for increasing cerebral blood flow (CBF) [122,123], augmenting brain energy metabolism [124,125], improving the antioxidant capacity [126], promoting cell growth [127], and improving the reparative ability of cells [128]. In the ophthalmic field, FR/NIR also had uneventful grades. ...
Introduction:
The aim of this article was to comprehensively review the relationship between light exposure and myopia with a focus on the effects of the light wavelength, illuminance, and contrast on the occurrence and progression of myopia.
Methods:
This review was performed by searching PubMed data sets including research articles and reviews utilizing the terms "light", "myopia", "refractive error", and "illuminance", and the review was concluded in November 2021. Myopia onset and progression were closely linked with emmetropization and hyperopia. To better elucidate the mechanism of myopia, some of the articles that focused on this topic were included. This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.
Results:
The pathogenesis and prevention of myopia are not completely clear. Studies have provided evidence supporting the idea that light could affect eye growth in three ways. Changing the corresponding conditions will cause changes in the growth rate and mode of the eyes, and preliminary results have shown that FR/NIR (far red/near-infrared) light is effective for myopia in juveniles.
Conclusion:
This review discusses the results of studies on the effects of light exposure on myopia with the aims of providing clues and a theoretical basis for the use of light to control the development of myopia and offering new ideas for subsequent studies.
... An additional device for clinicians to consider is the photonic stimulator, which has been used by NASA and sports teams to speed healing and diminish infection (e.g., Whelan, Smits, Buchmann, Whelan, & Turner, 2001). It may also be useful in clinical settings to potentiate stuck somatic or affective processing (U. ...
Neuroaffective Embodied Self Therapy (NEST): An Integrative Approach to Case Formulation and EMDR Treatment Planning for Complex Cases
... 8,9 Photobiomodulation (PBM), also known as lowlevel laser therapy, is a noninvasive treatment and has been widely used in clinics to accelerate the repair of tissues in human beings. [10][11][12] Many studies have reported that PBM mediated by laser plays a positive role in wound healing of DFU patients through promoting cell proliferation of keratinocyte and¯broblasts, neovascularization, and a reduction of in°ammation. 13 In recent years, the lightemitting diodes (LEDs)-mediated PBM is going to provide DFU patients with a more feasible and lower-cost therapeutic option. ...
Photobiomodulation (PBM) promoting wound healing has been demonstrated by many studies. Currently, 630 nm and 810 nm light-emitting diodes (LEDs), as light sources, are frequently used in the treatment of diabetic foot ulcers (DFUs) in clinics. However, the dose–effect relationship of LED-mediated PBM is not fully understood. Furthermore, among the 630nm and 810nm LEDs, which one gets a better effect on accelerating the wound healing of diabetic ulcers is not clear. The aim of this study is to evaluate and compare the effects of 630nm and 810nm LED-mediated PBM in wound healing both in vitro and in vivo. Our results showed that both 630nm and 810nm LED irradiation significantly promoted the proliferation of mouse fibroblast cells (L929) at different light irradiances (1, 5, and 10mW/cm2). The cell proliferation rate increased with the extension of irradiation time (100, 200, and 500s), but it decreased when the irradiation time was over 500s. Both 630nm and 810nm LED irradiation (5mW/cm2) significantly improved the migration capability of L929 cells. No difference between 630nm and 810nm LED-mediated PBM in promoting cell proliferation and migration was detected. In vivo results presented that both 630nm and 810nm LED irradiation promoted the wound healing and the expression of the vascular endothelial growth factor (VEGF) and transforming growth factor (TGF) in the wounded skin of type 2 diabetic mice. Overall, these results suggested that LED-mediated PBM promotes wound healing of diabetic mice through promoting fibroblast cell proliferation, migration, and the expression of growth factors in the wounded skin. LEDs (630nm and 810nm) have a similar outcome in promoting wound healing of type 2 diabetic mice.
... The levels of growth factors did not show a significant difference in the comparison between control and irradiated membranes. However, some studies have shown that laser therapy is able to promote the increase or biomodulation of growth factors, such as VEGF, FGF-2, EGF, PDGF, and TNFα, and TGF-ß [28][29][30] . However, in rat calvarial defects filled with xenograft and covered with the collagen membrane, the photobiomodulation provided a greater amount of bone volume only during the first 14 days after surgery 14 . ...
Purpose:
To evaluate the low-level laser therapy (LLLT) on the membrane induced by the Masquelet technique in rabbits.
Methods:
Twelve Norfolk rabbits at approximately 3 months of age were used. A 1-cm segmental defect was induced in both radii, which were filled with polymethylmethacrylate cylinder. LLLT was used postoperatively in the bone defect of one of the forelimbs every 48 hours for 15 days. Six rabbits were euthanatized on third and sixth postoperative weeks.
Results:
In both forelimbs, radiographs showed new bone growth from radius cut ends on the third postoperative week and more advanced stage on the sixth postoperative week. Ultrasound showed induced membrane one week after the surgery. Histologically, there were no significant differences in the semi-quantitative score of inflammation intensity, total number of blood vessels, bone metaplasia, and collagen. The average thicknesses were 2,050.17 and 1,451.96 μm for control membranes and 2,724.26 and 2,081.03 μm for irradiated membranes, respectively, on third and sixth postoperative weeks. Vascular endothelial growth factor A (VEGF-A) and platelet derived growth factor (PDGF) expression were present in the induced membranes of control and irradiated forelimbs, but there was no significant difference.
Conclusions:
Based on assessment methods, it was not possible to demonstrate the effect of LLLT on the induced membrane.
... Laser bio-stimulation largely influences the cell proliferation phase of the wound healing process [24]. Mitochondria are sensitive to monochromatic near-infrared light, and laser light appears to boost respiratory metabolism in some cells [25,26]. ...
... There is a nonsignificant difference between two of the control conditions: light alone and photosensitizers alone, which is a common phenotype in an in vivo model. This is likely due to the application of light alone accelerating wound healing and increasing the host immune response resulting in a minor decrease in bacterial burdens (25,38,39). There is great potential to further refine this animal model and to explore the use of this therapeutic regimen for other Gram-positive pathogen derived SSTIs. ...
Staphylococcus aureus is a serious threat to public health due to the rise of antibiotic resistance in this organism, which can prolong or exacerbate skin and soft tissue infections (SSTIs). Methicillin-resistant S. aureus is a Gram-positive bacterium and a leading cause of SSTIs. As such, many efforts are underway to develop therapies that target essential biological processes in S. aureus . Antimicrobial photodynamic therapy is effective alternative to antibiotics, therefore we developed an approach to simultaneously expose S. aureus to intracellular and extracellular photoactivators. A near infrared photosensitizer was conjugated to human monoclonal antibodies (mAbs) that target the S. aureus Isd heme acquisition proteins. Additionally, the compound VU0038882 was developed to increase photoactivatable porphyrins within the cell. Combinatorial PDT treatment of drug-resistant S. aureus exposed to VU0038882 and conjugated anti-Isd mAbs proved to be an effective antibacterial strategy in vitro and in a murine model of SSTIs.
... In this study, we used DCFH probe to detect ROS, and the green fluorescence value was proportional to the level of ROS [6]. ROS is the normal metabolite of redox reactions in the cell, mainly coming from the mitochondrial respiratory chain, ROS is related to mitochondrial oxidative phosphorylation, apoptosis, immunity, and inflammation [25][26][27][28][29][30]. In this study, HGFs were stimulated by 16 µg/mL LPS, the production of intracellular ROS increased. ...
Periodontal disease is the most common oral chronic inflammatory disease in humans. Recent studies have indicated that red light Photobiomodulation (PBM) could inhibit cell inflammation effectively, but the effect of different doses of PBM on the treatment of inflammation has to be improved. Thus, this study was aimed to investigate the effects of various doses of PBM (630 ± 30 nm, (1) 5 mW/cm2, 1 J/cm2, 200 s; (2) 5 mW/cm2, 3 J/cm2, 600 s; (3) 5 mW/cm2, 9 J/cm2, 1800 s; (4) 5 mW/cm2, 18 J/cm2, 3600 s; (5) 5 mW/cm2,36 J/cm2, 7200 s) on the anti-inflammatory response of human gingival fibroblasts. Our results suggested that PBM (630 ± 30 nm) with doses of 18 J/cm2 and 36 J/cm2 could significantly inhibit the production of inflammatory cytokines such as Prostaglandin E2 (PGE2) and IL-8, presumably due to the fact that a high dose of PBM treatment could reduce intracellular Reactive oxygen species (ROS) in human gingival fibroblasts, thus reducing the expression of COX-2 enzyme. In addition, it was found that treatment with different doses of PBM (630 ± 30 nm) did not result in reduced mitochondrial membrane potential and mitochondrial dysfunction in human gingival fibroblasts. Our study provides a theoretical reference for the selection of PBM parameters and the application of PBM in the clinical treatment of periodontitis.
... For phototherapy, there are several active response bands in the red and far-red regions: i) 613-623 nm; ii) 667-683 nm; iii) 750-772 nm [4,5]. It is reported that exposure to 670 or 726 nm LEDs can shorten the healing time of chronic ischemic ulcers in rats [6,7]. Therefore, the achievement of novel red/ Far-infrared sources would significantly promote the development of plant cultivation and phototherapy. ...
Recently, Far-infrared Light Emitting Diodes have attracted considerable interest in the research field worldwide. Emerging light therapy requires effective red/far-infrared light resources in clinical and plant photomorphogenesis to target or promote the interaction of light with living organisms. Here, Gd 3 Al 4 GaO 12 :Cr ³⁺ (hereinafter referred to as: GAGG:Cr ³⁺ ) phosphor was synthesized by high-temperature solid-phase method, and the crystal structure, morphology, and luminescence properties of this series of phosphor samples were studied. Through X-ray powder diffraction to obtain pure phase GAGG:Cr ³⁺ series phosphor. Under the excitation of 420nm blue light, a broad band emission from 640 to 850nm is obtained, which is the result of the transition of Cr ³⁺ ⁴ T 2 → ⁴ A 2 level. A sharp emission peak at 693nm is the R line belonging to Cr ³⁺ in Gd 3 Al 4 GaO 12 garnet. R line is assigned to the spin-forbidden ² E→ ⁴ A 2 transitions of Cr ³⁺ ions that occupy the ideal octahedral sites. As the Cr ³⁺ doping concentration increases, the luminous intensity of the sample increases first and then decreases. When the doping concentration of Cr ³⁺ is 0.1mol phosphor,the luminous intensity is strongest at one single broad peak at about 712nm. At 440k, the R sharp line (693nm) and broad band (712nm) emission intensity maintained 78.6% and 71.8% , compared to room temperature intensity, respectively. The change of fluorescence lifetime at different temperatures gives the mechanism of fluorescence change with temperature. The current exploration will pave a promising way to engineer GAGG:Cr ³⁺ activated optoelectronic devices for all kinds of photobiological applications.
... 5 Next through their NASA LED wound healing studies, Whelan et al. showed that useful bio-reactions could be achieved by the use of LEDs without any heat or damage through their ability of cellular photoactivation. 10 LPT is a relatively new phenomenon and started appearing regularly in the literature only since 2001, where focus was on the redand near-infrared radiation and their various effects at the physiological levels. 5 FDA deemed NIR -LED light therapy to be a nonsignificant risk for approved use in humans 11 and US photobiologist, Kendric C Smith renamed low level laser therapy as 'Low level light therapy' (LLLT) to encompass LED energy. ...
BACKGROUND Photobiomodulation is an emerging area of medical and dental science that has gained attention in numerous clinical fields with the advent of new generational light - emitting diodes (LEDs), as evident in the extent of published scientific literature in recent years. The rationale behind LED - mediated photobiomodulation therapy (LPT) is that at certain biologically active wavelengths, LEDs have shown to have therapeutic effects at the cellular and subcellular levels and are an efficient alternative photon source after lasers, along with their numerous benefits. Subsequent to favourable in-vitro, animal and recently human clinical trials, considerable attention has been garnered towards the promising applications and the integration of LPT with traditional therapeutic protocols, including in orthodontics. Originally started and accepted as a modality in acceleration of tooth movement, pain management and increasing the bone remodelling rate and quality, the advancements in this therapeutic technology have created new avenues in the treatment of temporomandibular disorders, root resorption, bone consolidation during maxillary expansion and distraction osteogenesis, as well as for improvement in miniscrew stability. Since it is non-invasive, easy to perform and user friendly with reported efficacy, an established consensus of wavelengths and parameters with respect to guidance for clinical use will go a long way in enabling the successful achievement of numerous objectives. This review article of published research intends to evaluate the adjunctive applications of LPT within orthodontic treatment at several levels along with the underlying mechanism, parameters and reported outcomes. KEY WORDS Photobiomodulation Therapy, Light Emitting Diodes, LED - Mediated Phototherapy, Low Level Light Therapy, NIR-LED, Light Accelerated Orthodontics
... The fluorescent technology of the LumiHeal gel is based on the ability of particular molecules (chromophores) to capture light emitted by a blue LED lamp and then to convert it into a different and wider emission spectrum in the visible spectrum (fluorescence) with a longer wavelength and therefore with lower energy 2 (wavelength range emitted: 532-615 nm). Several studies have shown that the most effective wavelengths in penetrating the skin and promoting healing are those of blue, green, yellow, and orange; each wavelength corresponds to a precise biological effect (Table 1) [13][14][15] ; the main feature of the LumiHeal system is precisely that of maximizing the therapeutic effect of photobiomodulation by causing the wound to be irradiated simultaneously by several different wavelengths. The progression of the process is visually controllable, thanks to the color variations of the gel in the various phases: at the time of application, the gel appears orange; the activated gel appears intense yellow and once exhausted it turns pink transparent. ...
Background:
Chronic ulcers represent a challenge for healthcare professionals and a large expense for national health care systems for their difficulty in achieving complete healing and for their high incidence of recurrence. With the progressive aging of the general population, the incidence of these injuries will only increase, further affecting the public health budget, hence the need to find new strategies for their management. The purpose of this study was to share the experience of the Complex Operational Unit of Plastic Surgery of the University Hospital of Padua with fluorescent light energy therapy, outlining its role in the treatment of chronic ulcers in the daily use outside the previous EUREKA study.
Methods:
In this case series study, we enrolled 15 patients with chronic ulcers of any etiology between January 2018 and July 2019 and we treated them using fluorescence light energy. We evaluated efficacy and safety endpoints reporting data in excel files completed by medical staff during the study.
Results:
The study confirms the effectiveness of fluorescent light energy inducing chronic ulcer healing, regardless of etiology, or at least preparing the lesions for a skin graft closure surgery. The system showed a low rate of complications established by patient adherence to treatment. Patients also reported a reduction in pain both at home and during outpatient dressings.
Conclusion:
Based on our experience, fluorescent light energy shows an excellent safety and efficacy profile in chronic ulcers no more responsive to traditional dressings and/or surgery.
Purpose
The aim of this integrative review was to analyze existing studies in the literature on the effects of LLL for hyposalivation and xerostomia in SS to establish parameters for safe use of LLL, using the guiding question “What is the effectiveness of Low-Level Laser in reducing xerostomia and hyposalivation in patients with Sjogren’s Syndrome?“.
Methods
Specific descriptors were applied to the Web of Science, Pub Med, Embase and LILACS databases and 31 articles were found, remaining 23 after removing duplicates. After reading the titles and abstracts only 5 were selected for reading the full text and 2 were included in this review. The data were arranged in tables and analyzed comparatively.
Results
The studies presented distinct results that made it difficult to develop a suggestive treatment plan. However, analyzing the literature and the known characteristics of LLL, distinct elements among them may be related to the results found, such as irradiation time, tissue pathology, and skin color of the patients.
Conclusion
It was concluded that the scarcity of studies and the discordance of the results found made it impossible to establish a plan for the application of LLL for xerostomia and hyposalivation in individuals with SS.
Das Angebot an therapeutischen Laser- und LED-Geräten ist groß und unübersichtlich. Doch welches ist für welche Zwecke am besten geeignet und vor allem: Wie und warum wirkt es? Um sich im Dschungel an unterschiedlichen Informationen und Angeboten zurechtzufinden, ist es hilfreich, auf ein fundiertes Verständnis der physikalischen Grundlagen sowie Kenntnisse über die aktuelle Evidenzlage zurückgreifen zu können. Damit legt man eine solide Basis für informierte Entscheidungen. Der nachfolgende „Kompass“ erklärt die wichtigsten Parameter und Hintergründe.
Repeated low-level red-light (RLRL), characterized by increased energy supply and cellular metabolism, thus enhancing metabolic repair processes, has gained persistent worldwide attention in recent years as a new novel scientific approach for therapeutic application in myopia. This therapeutic revolution led by RLRL therapy is due to significant advances in bioenergetics and photobiology, for instance, enormous progresses in photobiomodulation regulated by cytochrome c oxidase, the primary photoreceptor of the light in the red to near infrared regions of the electromagnetic spectrum, as the primary mechanism of action in RLRL therapy. This oxidase is also a key mitochondrial enzyme for cellular bioenergetics, especially for the nerve cells in the retina and brain. In addition, dopamine (DA)-enhanced release of nitric oxide may also be involved in controlling myopia by activation of nitric oxide synthase, enhancing cGMP signaling. Recent evidence has also suggested that RLRL may inhibit myopia progression by inhibiting spherical equivalent refraction (SER) progression and axial elongation without adverse effects.
In this review, we provide scientific evidence for RLRL therapy as a unique paradigm to control myopia and support the theory that targeting neuronal energy metabolism may constitute a major target for the neurotherapeutics of myopia, with emphasis on its molecular, cellular, and nervous tissue levels, and the potential benefits of RLRL therapy for myopia.
Background:
Numerous mechanisms, mostly molecular, have been tested and proposed for photobiomodulation. Photobiomodulation is finding a niche in the treatment of conditions that have no gold-standard treatment or only partially effective pharmacological treatment. Many chronic conditions are characterised by symptoms for which there is no cure or control and for which pharmaceuticals may add to the disease burden through side effects. To add quality to life, alternate methods of symptom management need to be identified.
Objective:
To demonstrate how photobiomodulation, through its numerous mechanisms, may offer an adjunctive therapy in inflammatory bowel disease. Rather than considering only molecular mechanisms, we take an overarching biopsychosocial approach to propose how existing evidence gleaned from other studies may underpin a treatment strategy of potential benefit to people with Crohn's disease and ulcerative colitis.
Main findings:
In this paper, the authors have proposed the perspective that photobiomodulation, through an integrated effect on the neuroimmune and microbiome-gut-brain axis, has the potential to be effective in managing the fatigue, pain, and depressive symptoms of people with inflammatory bowel disease.
Recent studies showed that green wavelength light-emitting diodes (LEDs) were effective for wound healing in various animal models, including olive flounder. However, determining the optimal light intensity for phototherapy is very important for accelerating wound healing and safety. Therefore, the purpose of this study was to investigate the optimal intensity of green LEDs (520 nm) for accelerating wound healing using olive flounder Paralichthys olivaceus (Temminck et Schlegel). In vitro studies, A Paralichthys olivaceus-derived embryo cell line (Hirame natural embryo cells; HINAE) was used to verify the proliferative effects of various intensities (20, 40, 80, and 120 μmol·m−2·s−1) of green LED (520 nm) light in 24-h light for seven days. In vivo studies, artificial wounds (4 mm in diameter) were made in flounders using a biopsy punch, and the wounds were exposed to green LED (520 nm) light at 20, 40, and 60 μmol·m−2·s−1, as well as ambient light as a control, in 12-h light/ dark cycles for 28 days. The results showed that 520 nm LED treatment at 40 μmol·m−2·s−1 significantly stimulated HINAE cell proliferation relative to ambient light (3±1 μmol·m-2·s-1) and the 20, 80 and 120 μmol·m−2·s−1 LED intensity groups. The relative wound healing rate of fish exposed to 40 μmol·m−2·s−1 of green LED (520 nm) light was significantly higher than that of the other groups and showed a high expression of wound healing-related genes such as matrix metalloproteinase (mmp)-9, mmp-13, epidermal growth factor (egf), and vascular endothelial growth factor (vegf)-. After the injuries, the survival rate of fish exposed to 520 nm LED light at an intensity of 60 μmol·m−2·s−1 was markedly lower (82%) than those of the control and 20 and 40 μmol·m−2·s−1-treated groups (over 95%). Stress-related factors such as catalase and superoxide dismutase (SOD) in the fish wound areas and serum glucose levels were significantly increased in the 60 μmol·m−2·s−1 exposure group, showing that prolonged exposure to strong light intensity could negatively affect physiology and wound healing. Therefore, the results showed that 40 μmol·m−2·s−1 intensity green LED (520 nm) light was the most effective light condition for accelerating wound healing in olive flounder.
The aim of this study was to examine the inhibitory effect of blue light (BL) on the proliferation of metastatic cancer cells and synergistic properties with chemo‐drugs. BL significantly inhibited the proliferation of B cell lymphoma (A20 and RAMOS) cells in a dose‐dependent manner. Anti‐proliferative effect of BL irradiation was identified to be associated with the inhibition of proliferating‐cell nuclear antigen expression and cell cycle by decreasing S‐phase cells. Consistent with its inhibitory effects, BL irradiation at 20 J/cm2 daily for 10 days inhibited metastasis of cancer cells which were distributed and invaded to other organs including bone marrow, liver, kidney, etc., and induced paraplegia, thereby leading to an increased survival rate of tumor‐bearing mice. Anti‐proliferative activity of BL was expanded in solid tumor cells including pancreatic carcinoma (Mia PaCa‐2, PANC‐1), lung carcinoma A549, and colorectal carcinoma HCT116 cells. Additionally, combination with chemo‐drugs such as 5‐FU and gemcitabine resulted in an increase in the anti‐proliferative activity after BL irradiation accompanied by regulating mRNA translational process via inhibition of p70S6K, 4EBP‐1, and eIF4E phosphorylation during cellular proliferation. These results indicate the anti‐metastatic and photo‐biogoverning abilities of BL irradiation as a potent therapeutic potential for repressing the progression of tumor cells.
The dynamic nature of the wound healing is a well-studied process. With the rapid evolution of healthcare science, efforts are being made to design newer therapies, along with advancement in the available technologies. In this regard, a detailed knowledge about the molecular mechanisms underlying the healing process is necessary to develop a more effective and targeted therapeutic method. In addition to improve the therapeutic techniques, various wound healing models also need to be designed and studied for understanding the associated molecular intricacies of each phase of the healing process. Novel technologies are being combined with the long-practiced traditional therapeutic methods with the object of achieving a synergistic effect for faster healing with minimal scarring. With technological development, non-invasive wound assessment methods are being implemented by utilizing various imaging techniques and electromagnetic radiations, to minimize painful invasive wound analysis. Smart devices are also been developed with an aim to monitor the healing process in real time, which provides the ability to modulate treatment procedures according to the rate of healing. This chapter aims to give a brief overview on the emerging therapeutic methods which are being developed to aid in wound management strategies. An overview of the different invasive and non-invasive wound assessment and monitoring methods along with mathematically designed wound assessment models is also discussed in a nutshell. This would provide an idea about the possible areas for development on the currently available strategies for improving the healthcare and well-being of individuals.
In an era of global warming knowledge of the effects of solar radiation on humans is of great importance and the latest discoveries in environmental photobiology are presented in this book. The Editor has brought together a wide range of world class contributors to provide the reader with information on the clinical effects of solar radiation, such as inflammation, pigmentation, immune-suppression, cancer and aging, with emphasis on the ethnic or genetic background. The book also offers updates on the biochemical mechanisms involved in the generation of damage to DNA, lipids and proteins and on their removal. Each chapter has been written to provide a "historical" description of the phenomenology followed by the description of the state of the art. In this way, non-specialized and specialised readers alike can be updated in the essential aspects of the field. Key topics include: - Damages from acute versus chronic sun exposure - Skin Color, Melanin, Race/Ethnicity and UV-Induced DNA Damage - The effects of solar radiation on the immune response in humans - Genetic background and UV-induced skin cancer - The photochemistry of indirect damages: Lipid and Protein Damage provoked by UV radiation - DNA repair therapy This title will become an indispensable resource for students and professional at all levels working in fields relating to photochemistry, environmental science, biochemistry and biotechnology.
Near-infrared (NIR) phosphor have attracted great attention due to its promising applications in bioimaging, night vision, medical diagnosis and food safety. However, the development of NIR phosphors with excellent sensing properties still remains a challenge. In this study, NIR phosphor LaGaO3: Nd/Cr has been successfully synthesized. Excitation at 460 nm the phosphor can exhibit excellent temperature sensing performance with the maximum absolute sensitivity 0.6043% K⁻¹. The NIR phosphor also displays distinguished anti-thermal quenching performance with the emission intensity at 573 K retaining 78.34% of that at room temperature. In addition, there is a linear fitting relationship between the luminescence intensity ratio and applying stress. More importantly, NIR phosphor-converted light-emitting diode (pc-LED) has been fabricated by combining LaGaO3: Nd/Cr phosphors with blue LED chips, which shows a NIR output power of 979 mW and a photoelectric conversion efficiency up to 7.79% at 280 mA. Utilizing the prepared NIR pc-LED as a light source, the distribution of blood vessels and bones in human palms can be clearly observed with the assistance of infrared camera. These results indicate that the produced NIR phosphors have a wide range of optical sensing applications.
Significance:
The method of photobiomodulation (PBM) has been used in medicine for a long time to promote anti-inflammation and pain-resolving processes in different organs and tissues. PBM triggers numerous cellular pathways including stimulation of the mitochondrial respiratory chain, alteration of the cytoskeleton, cell death prevention, increasing proliferative activity, and directing cell differentiation. The most effective wavelengths for PBM are found within the optical window (750 to 1100 nm), in which light can permeate tissues and other water-containing structures to depths of up to a few cm. PBM already finds its applications in the developing fields of tissue engineering and regenerative medicine. However, the diversity of three-dimensional (3D) systems, irradiation sources, and protocols intricate the PBM applications.
Aim:
We aim to discuss the PBM and 3D tissue engineered constructs to define the fields of interest for PBM applications in tissue engineering.
Approach:
First, we provide a brief overview of PBM and the timeline of its development. Then, we discuss the optical properties of 3D cultivation systems and important points of light dosimetry. Finally, we analyze the cellular pathways induced by PBM and outcomes observed in various 3D tissue-engineered constructs: hydrogels, scaffolds, spheroids, cell sheets, bioprinted structures, and organoids.
Results:
Our summarized results demonstrate the great potential of PBM in the stimulation of the cell survival and viability in 3D conditions. The strategies to achieve different cell physiology states with particular PBM parameters are outlined.
Conclusions:
PBM has already proved itself as a convenient and effective tool to prevent drastic cellular events in the stress conditions. Because of the poor viability of cells in scaffolds and the convenience of PBM devices, 3D tissue engineering is a perspective field for PBM applications.
Widespread in nature ability of biological objects to emit photons (biophotons) made it possible to create devices for non-invasive and continuous monitoring of the metabolism of organs and tissues, used as a powerful clinical diagnostic tool, as well as for visualisation and spatio-temporal analysis of functioning organs and, in particular, the brain. Numerous experimental data indicating the participation of biophotons in the processes of inter- and intracellular communication served as a theoretical basis for the medical use of low-intensity light therapy for the effective treatment of a wide range of diseases, including delayed wound healing, pain in arthritis, and acute stroke.
The aim of this study was to evaluate the effectiveness of pain modulation following Laser or LED phototherapies during the process of tooth separation. This was a longitudinal randomized controlled clinical trial in four observational times carried out in 60 patients (15 males, 45 females, average 24.1 years old) who were randomly divided into three groups: G1 (LED, AsGaAl, λ850 ± 10 nm, 150 mW, 17 J/cm², 57 s per session), G2 (Laser, AsGaAl, λ780 nm, 70 mW, 20.0 J/cm², 240 s per session) and G3 (Non-irradiated Control). All patients were submitted to tooth separation using elastomeric separators. The pain level was measured by using a visual analogue scale (VAS) immediately after insertion (T1) of the elastic, at 48 (T2), 96 (T3) hours and 6 days (T4). It was observed an increase of the pain on the Control group from T1 to T2, with statistical significance. Pain levels in the LED and Laser groups were always significantly lower (<0.001), except for T1. According with the results of the present study it may be concluded that, either LED or Laser phototherapies, were effective in reducing the pain level after dental separation process when compared to the control group.
To explore the safety and feasibility of low fluence intense pulsed light (IPL) for treating pediatric patients with moderate-to-severe blepharitis and to analyze potential factors associated with the recovery of meibomian glands (MG) dropout, a retrospective, noncomparative study, including 17 blepharitis patients (33 eyes) aged between 5 and 16 years old was conducted. All of the participants were given 4 continuous sessions of low-fluence (9–12 J/cm2) IPL at 3–4 week intervals. Corneal fluorescein staining (CFS), tear breakup time (BUT), inferior tear meniscus height, Demodex presence, and MG morphology were examined before and after the treatment. Results indicated that CFS, BUT and MG morphology (central/total gland area ratio and gland signal index) had significantly improved (p < 0.05). Symptoms and signs such as severe corneal neovascularization, limbal pannus and conjunctival congestion also subsided. Among age, gender, presence of Demodex and interval before diagnosis, age initiating the formal treatment was confirmed as a negatively correlated factor of the recovery of MG dropout (p = 0.032, B = −1.755). No notable adverse events were reported. In conclusion, low fluence IPL seems to be a safe and effective alternative for moderate-to-severe pediatric blepharitis, and MG dropout is prone to recover in younger patients.
Gallium is a soft, silvery metal with an atomic number of 31. Gallium compounds are used in semiconductor materials, optoelectronic devices (e.g., laser diodes, light-emitting diodes photodetectors, and solar cells), cancer and malaria chemotherapy, antimicrobial, and dental materials. The production of gallium continues to increase due to the demand for high-powered radio frequency smartphones. Analytical methods for gallium include atomic absorption/emission spectrometry, X-ray fluorescence, and, more recently, inductively coupled plasma mass spectrometry. The main health concerns for gallium have been centered on workers in the semiconductor industry engaged in the production of gallium-based devices; however, monitoring of workers is sparse. Gallium is transported in the circulation bound to transferrin. Its competition with iron for transferrin-binding might account for its being an anticancer, antimicrobial agent, antifungal agent, or antiparasitic agent. Toxicity studies in experimental animal systems have shown gallium nitrate, gallium arsenide, and gallium oxide to produce toxicity to the lungs, immune system, kidneys, and hematopoietic systems. The International Agency for Research on Cancer has classified gallium arsenide as a human carcinogen. Studies of semiconductor workers are limited, but clinical trials in humans treated with gallium nitrate for various cancers have demonstrated renal toxicity as the primary side effect.
Purpose: To investigate the efficacy of intense pulsed light (IPL) treatment in patients with meibomian gland dysfunction (MGD) associated with Sjögren’s syndrome.Methods: This study included 43 patients with MGD and Sjögren’s syndrome. Patients received either IPL with meibomian gland expression (IPL/MGX) (n = 22) or MGX only (n = 21). Treatments were administered three times at a 3-week interval. Patients were followed up 6 weeks after the end of the treatment. Ocular Surface Disease Index (OSDI), tear film breakup time with fluorescein dye (FBUT), non-invasive tear breakup time, tear meniscus height (TMH), Schirmer test, SICCA ocular surface staining score, meibum quality score (MQS), and meibum expression score (MES) were evaluated at each visit. Meibomian gland dropouts (meiboscore) and tear film lipid layer grade were measured using keratography.Results: OSDI, FBUT, corneal surface staining score, MQS, meiboscore, and tear film lipid layer grade improved after IPL/MGX treatment (p < 0.05). In both treatment groups, MES significantly improved (p < 0.01 and p < 0.05 for IPL/MGX and MGX groups, respectively). The Schirmer test score, conjunctival surface staining score, and TMH after treatment were not significantly different between the groups. After treatment, the IPL/MGX group had significantly lower OSDI, FBUT, corneal staining score, MQS, and MES, but higher FBUT, compared with the MGX group (p < 0.05).Conclusions: IPL treatment effectively improved tear film, ocular surface parameters, meibomian gland function, and lipid layer grade in patients with Sjögren’s syndrome and MGD.
This work is supported and managed through the NASA Marshall Space
Flight Center-SBIR Program. Studies on cells exposed to microgravity and
hypergravity indicate that human cells need gravity to stimulate cell
growth. As the gravitational force increases or decreases, the cell
function responds in a linear fashion. This poses significant health
risks for astronauts in long termspace flight. LED-technology developed
for NASA plant growth experiments in space shows promise for delivering
light deep into tissues of the body to promote wound healing and human
tissue growth. This LED-technology is also biologically optimal for
photodynamic therapy of cancer. .
Different types of osteoblast behavior result from external stimulation in the early and in the late stages of cell differentiation. The purpose of this study was to investigate the influence of a diode laser on osteoblasts and to compare any effects between the proliferating and the differentiating phases. In the proliferating phases, the numbers of cells greatly increased in the laser irradiated group as compared with that of the control group. The increases in the numbers of cells in the differentiating phase were no greater than were those in the proliferating phase. The alkaline phosphatase activity of cells in the proliferating phase was highest 5 days after the laser irradiation, however, the activity in the differentiating phase increased day by day. Although osteopontin mRNA levels in the proliferating phase increased in the first 3 days of culture and then decreased in both groups, this decrease of osteopontin mRNA was small in the irradiated group. In contrast, osteopontin mRNA expression in the differentiating phase increased at day 1 and then decreased in the control group, while osteopontin mRNA levels in the irradiated group did not decrease.
Space light-emitting diode
(LED) technology has provided medicine with a new tool capable of delivering light deep into tissues of the body, at wavelengths which are biologically optimal for cancer treatment and wound healing. This LED technology has already flown on Space Shuttle missions, and shows promise for wound healing applications of benefit to Space Station astronauts.
The acceleration of bone regeneration by low-intensity laser irradiation may hold potential benefits in clinical therapy in orthopedics and dentistry. The purpose of this study is to compare the effects of light-emitting diode (LED) and laser on pre-osteoblast MC3T3 proliferation and differentiation. Cells were irradiated with red, infrared, and LED (3 and 5 J/cm(2)). Lasers had a power density of 1 W/cm(2) and irradiation time of 2 and 5 s. LED had a power density of 60 mW/cm(2) and irradiation time of 50 and 83 s. Control group did not receive irradiation. Cell growth was assessed by a colorimetric test (MTT) (24, 48, 72, and 96 h), and cell differentiation was evaluated by alkaline phosphatase (ALP) quantification after growth in osteogenic medium (72 and 96 h and 7 and 14 days). At 24 h, the cell growth was enhanced 3.6 times by LED (5 J/cm(2)), 6.8 times by red laser (3 J/cm(2)), and 10.1 times by red laser (5 J/cm(2)) in relation to control group (p < 0.05). At the other periods, there was no influence of irradiation on cell growth (p > 0.05). The production of ALP was not influenced by irradiation at any period of time (p > 0.05). Low-intensity laser and LED have similar effects on stimulation of cell growth, but no effect on cell differentiation.
Iron deficiency impairs the formation of hemoglobin, red blood cells, as well the transport of oxygen. The wound healing process involves numerous functions, many of which are dependent on the presence of oxygen. Laser has been shown to improve angiogenesis, increases blood supply, cell proliferation and function. We aimed to study the effect of λ660 nm laser and λ700 nm light-emitting diode (LED) on fibroblastic proliferation on cutaneous wounds on iron-deficient rodents. Induction of iron anemia was carried out by feeding 105 newborn rats with a special iron-free diet. A 1 × 1 cm wound was created on the dorsum of each animal that were randomly distributed into seven groups: I, control anemic; II, anemic no treatment; III, anemic + L; IV, anemic + LED; V, healthy no treatment; VI, healthy + laser; VII, healthy + LED (n = 15 each). Phototherapy was carried out using either a diode laser (λ660 nm, 40 mW, 10 J/cm(2)) or a prototype LED device (λ700 ± 20 nm, 15 mW, 10 J/cm(2)). Treatment started immediately after surgery and was repeated at 48-h interval during 7, 14, and 21 days. After animal death, specimens were taken, routinely processed, cut, stained with hematoxylin-eosin, and underwent histological analysis and fibroblast counting. Significant difference between healthy and anemic subjects on regards the number of fibroblast between treatments was seen (p < 0.008, p < 0.001). On healthy animals, significant higher count was seen when laser was used (p < 0.008). Anemic subjects irradiated with LED showed significantly higher count (p < 0.001). It is concluded that the use of LED light caused a significant positive biomodulation of fibroblastic proliferation on anemic animals and laser was more effective on increasing proliferation on non-anemics.
The purpose of this was to evaluate the neuroprotective effects of near-infrared (NIR) light using an in-vivo rodent model of traumatic brain injury (TBI), controlled cortical impact (CCI), and to characterize changes at the behavioral and biochemical levels.
NIR upregulates mitochondrial function, and decreases oxidative stress. Mitochondrial oxidative stress and apoptosis are important in TBI. NIR enhanced cell viability and mitochondrial function in previous in-vitro TBI models, supporting potential NIR in-vivo benefits.
Sprague-Dawley rats were divided into three groups: severe TBI, sham surgery, and anesthetization only (behavioral response only). Cohorts in each group were administered either no NIR or NIR. They received two 670 nm LED treatments (5 min, 50 mW/cm(2), 15 J/cm(2)) per day for 72 h (chemical analysis) or 10 days (behavioral). During the recovery period, animals were tested for locomotor and behavioral activities using a TruScan device. Frozen brain tissue was obtained at 72 h and evaluated for apoptotic markers and reduced glutathione (GSH) levels.
Significant differences were seen in the TBI plus and minus NIR (TBI+/-) and sham plus and minus NIR (S+/-) comparisons for some of the TruScan nose poke parameters. A statistically significant decrease was found in the Bax pro-apoptotic marker attributable to NIR exposure, along with lesser increases in Bcl-2 anti-apoptotic marker and GSH levels.
These results show statistically significant, preclinical outcomes that support the use of NIR treatment after TBI in effecting changes at the behavioral, cellular, and chemical levels.
The aim of this study was to examine the reactive oxygen species (ROS) that are dissipated by 635 nm irradiation, and the effect of 635 nm irradiation on ROS scavenging system.
Intracellular ROS are produced in the form of superoxide anion by either nicotinamide adenine dinucleotide phosphate (NADPH) oxidase or xanthine oxidase in response to a number of stimuli. Low-level light irradiation decreases the intracellular ROS level and has been used in clinical situations for reducing the level of oxidative stress.
Human epithelial cells were exposed to exogenous and endogenous oxidizing agents that promote the generation of harmful ROS. These were then irradiated with 635 nm LED light, 5 mW/cm(2) for 1 h, 18 J/cm(2) or by 470 nm LED light, also 5 mW/cm(2) for 1 h, 18 J/cm(2) on a 9 cm cell culture dish. After irradiation, the MTT reduction method and malondialdehyde (MDA) colorimetric assay were performed in xanthine/xanthine oxidase (XXO)- or hydrogen peroxide (H(2)O(2))-treated HaCaT cells. The superoxide anion was detected by an electron spin resonance (ESR) spectrometer using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin trap and H(2)O(2) was assayed by flow cytometry using 2',7'-dichlorodihydrofluorescein diacetate (H(2)DCF-DA).
Irradiation at 635 nm enhanced cell viability in the XXO-treated HaCaT cells. Also, irradiation had a much lesser effect on cell viability in the HaCaT cells treated with exogenous H(2)O(2) as compared with that in cells treated with N-acetyl-L-cysteine. The level of the superoxide anion increased in response to XXO treatment, and then decreased after 635 nm irradiation. Irradiation with 635 nm led to a decrease in superoxide anion and lipid peroxidation levels in the presence or absence of diethyldithiocarbamate.
These results highlight the potential role of 635 nm irradiation in protection against oxidative stress by scavenging superoxide anions. Also, a pathway that is independent of the activities of intracellular enzymatic ROS scavengers, such as superoxide dismutase, glutathione peroxidase and catalase might be involved in its mechanism of action.
Background and Objective
Low-level laser irradiation at certain fluences and wavelengths can enhance the release of growth factors from fibroblasts and stimulate cell proliferation in vitro. We evaluated whether low-level laser irradiation can improve wound healing in diabetes mellitus.Study Design/Materials and Methods
Genetically diabetic mice (C57BL/Ksj/db/db) were used as the animal model for this wound healing study. The experimental animals were divided among four groups: negative control, positive control (topical basic fibroblast growth factor [bFGF] on wound), laser therapy group; and a combination group of laser therapy and topical bFGF. An argon dye laser (Lexel Auora Model 600) at a wavelength of 630 nm and an output of 20 mW/cm2 was used as the light source. The speed of wound closure and histological evaluation were used to analyze the experimental results.ResultsLaser irradiation enhanced the percentage of wound closure over time as compared to the negative control group (58.4 ± 2.6 vs. 40.8 ± 3.4 at day 10 and 95.7 ± 2 vs. 82.3 ± 3.6 at day 20, P < .01). Histological evaluation showed that laser irradiation improved wound epithelialization, cellular content, granulation tissue formation, and collagen deposition in laser-treated wounds as compared to the negative control group (6.4 ± 0.16 vs. 3.8 ± 0.13 at day 10 and 12 ± 0.21 vs. 8.2 ± 0.31, P < .01).Conclusion
This study of laser biostimulation on wound healing in diabetic mice suggests that such therapy may be of great benefit in the treatment of chronic wounds that occur as a complication of diabetes mellitus. Lasers Surg Med 20:56–63, 1997. © 1997 Wiley-Liss, Inc.
The aim of this study was to compare the effects of Low-intensity Laser Therapy (LILT) and Light Emitting Diode Therapy (LEDT)
of low intensity on the treatment of lesioned Achilles tendon of rats. The experimental model consisted of a partial mechanical
lesion on the right Achilles tendon deep portion of 90 rats. One hour after the lesion, the injured animals received applications
of laser/LED (685, 830/630, 880 nm), and the same procedure was repeated at 24-h intervals, for 10 days. The healing process
and deposition of collagen were evaluated based on a polarization microscopy analysis of the alignment and organization of
collagen bundles, through the birefringence (optical retardation-OR). The results showed a real efficiency of treatments based
on LEDT and confirmed that LILT seems to be effective on healing process. Although absence of coherence of LED light, tendon
healing treatment with this feature was satisfactory and can certainly replace treatments based on laser light applications.
Applications of infrared laser at 830 nm and LED 880 nm were more efficient when the aim is a good organization, aggregation,
and alignment of the collagen bundles on tendon healing. However, more research is needed for a safety and more efficient
determination of a protocol with LED.
The purpose of this study was to evaluate the clinical effectiveness of a LED phototherapy prototype apparatus in the healing of nipple trauma in breastfeeding women.
There is no scientific evidence of an effective treatment for nipple trauma.
The experimental group was treated with orientation on nipple care and adequate breastfeeding techniques in addition to active LED phototherapy. The control group was treated with orientation on nipple care and adequate breastfeeding techniques in addition to placebo LED phototherapy. Participants were treated twice a week, for a total of eight sessions. Healing of the nipple lesions was measured by a reduction in their area, and decrease in pain intensity was measured in accordance with an 11-point Pain Intensity Numerical Rating Scale and a standard 7-point patient global impression of change.
Statistically significant reductions in measured nipple lesion area (p<0.001) were observed for both the experimental and control groups with an increase in the number of treatment sessions. A significant difference between the experimental and control groups was observed for the healing of nipple lesions (p<0.001). The pain intensity was significantly reduced only in the experimental group (p<0.001).
Preliminary results demonstrated the prototype apparatus for LED phototherapy to be an effective tool in accelerating the healing of nipple trauma.
This work carried out a histological analysis on bone defects grafted (MTA) treated or not with LED, BMPs, and membrane (GBR). Benefits of their isolated or combined usage on bone repair were reported, but not their association. Ninety rats were divided into ten groups and each subdivided into three. Defects on G II and I were filled with the blood clot. G II was further LED irradiated. G III and IV were filled with MTA; G IV was further LED irradiated. In G V and VI, the defects were filled with MTA and covered with a membrane (GBR). G VI was further LED irradiated. In G VII and VIII, BMPs were added to the MTA and group VIII was further LED irradiated. In G IX and X, the MTA + BMP graft was covered with a membrane (GBR). G X was further LED irradiated. LED was applied over the defect at 48-h intervals and repeated for 15 days. Specimens were processed, cut, and stained with H&E and Sirius red and underwent histological analysis. The use of LED light alone dramatically reduced inflammation. However, its use on MTA associated with BMP and/or GBR increased the severity of the inflammatory reaction. Regarding bone reabsorption, the poorest result was seen when the LED light was associated with the MTA + BMP graft. In the groups Clot and MTA + GBR, no bone reabsorption was detectable. Increased collagen deposition was observed when the LED light was associated with the use of the MTA associated with BMP and/or GBR. Increased new bone formation was observed when the LED light was used alone or associated with the use of MTA + GBR, MTA + BMP, on association of MTA + BMP + GBR and when BMP was added to the MTA. Our results indicate that the use of LED light alone or in association with MTA, MTA + BMP, MTA + GBR, and MTA + BMP + GBR caused less inflammation, and an increase of both collagen deposition and bone deposition as seen on both histological and morphometric analysis.
According to earlier in vitro low level laser therapy (LLLT) studies, wavelengths in the red and near infrared range, that are absorbed by cytochrome oxidase, stimulate cell growth and hence wound healing. Wavelengths in the blue region that are absorbed by flavins were found to exert a bactericidal effect that is very important for treating infected wounds. However, as far as therapeutic application of light is concerned, penetration into the tissue must be considered. For this purpose we estimated the penetration depth as a function of the relevant wavelengths, using the formulae of the photon migration model for skin tissue.
We use the photon diffusion model, which is an analytical model for describing light transfer in biological tissues. We refer to the most common chromophores in human tissue and evaluate their volume fraction and concentration in skin cells. These empirically estimated mean wavelength-dependent absorption coefficients are then substituted in the theoretical expressions for the optical penetration depth in the tissue. The wavelengths, for which the penetration depth is the highest, are the optimal wavelengths to be used in wound healing treatments.
Our model suggests that the optimal wavelengths for therapeutic treatments are in the red region with a local maximum at 730 nm. As to the blue region, a local maximum at 480 nm was found.
Light at 480 nm should be used for treating infected wounds followed by 730 nm light for enhancing wound closure.
An alternative approach in the treatment of acne vulgaris is photodynamic therapy (PDT) that uses light and aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) production to eradicate Propionibacterium acnes found in acne lesions. PpIX formation is dependent on ALA percutaneaous penetration. In this study, to enhance ALA penetration and subsequent accumulation of PpIX, skin temperature was increased with radiant infrared (IR) prior to ALA-PDT application and compared to ALA-PDT alone in the treatment of inflammatory acne.
Ten patients exhibiting inflammatory acne with a lesion count of > or =10 were assigned to a split face or split back group. One side was pre-treated for 15 minutes with radiant IR light emitting diode (LED) (970 nm), while the other side was used as control. ALA was then applied after which PDT LED (630 nm) was performed on the entire face or back surface. Blinded lesion counts and clinical global assessment of severity were performed based on digital photographs before and 4 weeks after the PDT procedure.
This randomized, controlled, and rater-blinded trial revealed a significant difference in median reduction of inflammatory lesions on the IR pre-treated (73%, 95% confidence interval (CI) 51-81%) versus the control side (38%, 95% CI 8-55%) 1 month after PDT (P<0.0001). Clinical assessment of severity was also significantly lower on the IR-treated side than on the control side (median 1, 95% CI 0.74-1.34 vs. 2, 95% CI 1.17-1.72). No unusual treatment-related adverse effects were observed.
The reported therapeutic effects may be due to enhanced induction of alterations in transcutaneous diffusion kinetics of the photosensitizer at higher skin temperature and/or conversion of ALA to PpIX. Pre-PDT radiant IR LED exposure appears to be a promising method to enhance PDT efficacy for the treatment of acne lesions.
This paper reviews studies on the basic principles of biostimulation of wound healing by various low-energy lasers. It looks at the mechanism of action of biostimulation as well as the lasers effect on cell proliferation, collagen synthesis, and would healing.
Aim of the study was to compare different wavelength laser immunological reactions.
The mechanism of wound healing was studied with 35S, 14C labelled amino acids during the early proliferative phase, following artificial incision. The measurements show that 4 joule laser energy applied at the earliest time favourably influences wound healing; the production of collagen in the cicatricial tissue treated with laser exceeds that of the control by about 30-50 per cent.
Introduction: Light-emitting diode (LED) therapy uses different wavelengths of light and has been reported to accelerate cutaneous wound healing. Carnosic acid is an antioxidant that is also thought to be photoprotective. We designed an in vitro study to examine the effects of LED and carnosic acid on the proliferation and migration of human keratinocytes.
Materials and Methods: Clinically normal human keratinocytes were cultured and exposed to two wavelengths: 620 nm and 660 nm LED at different ß uences. In the second part of this study, a different batch of human keratinocytes was grown in culture, and different concentrations of carnosic acid were added.
Results: At the two wavelengths that were used, LED did not appear to have any therapeutic effect and was not effective in stimulating keratinocyte proliferation. Exposure to greater energy levels (increased fluence) produced increased cell damage that was directly proportional to the increase in energy. On the other hand, treatment of the cell cultures with the antioxidant carnosic acid resulted in an increase of keratinocyte cell proliferation, and this increase was also proportional to the concentration of carnosic acid.
Conclusions: This study did not support the hypothesis that LED treatment results in keratinocyte proliferation; however, carnosic acid, a potent antioxidant, stimulated keratinocyte production and could be implicated in wound healing and rejuvenation.
IntroductionLED light therapy with magnetostimulation (magnetoledtherapy) has a vast range of applications in the treatment of neurological, rheumatic and orthopedic illnesses. In some cases it serves as an alternative procedure to pharmacological treatment, in particular to nonsteroidal anti-inflammatory drugs.AimThe aim of this study was to discuss the use of magnetoledtherapy in the rehabilitation of children.Materials and methodsThis article is a review of selected literature and other available source materials.DiscussionDue to biological hysteresis, therapeutic outcomes of magnetoledtherapy appear later than in the case of other physical therapy methods; they last longer, even up to several months after the exposure, thus leading to more beneficial treatment effects. Therapeutic methods available for very young people are limited due to various contraindications. When exposure conditions are carefully considered and accounted for, magnetoledtherapy can be applied even in infants, serving as a beneficial complement to kinesiotherapy. Children willingly participate in such treatment because magnetoledtherapy produces few side effects and has a positive effect on a patient's well-being following the application. Selected indications for the use of this method in children include neuralgias, juvenile rheumatoid arthritis, collagenoses, aseptic necrosis, osteoporosis, tendinitis, tendovaginitis, bursitis, injuries without a disruption in tissue continuity including sprains, bruises and fractures, improvement in the quality and time of healing, burns, effects of exposure to sunlight and laser light, neonatal physiological jaundice, dermatoses including dermatitises, acne, herpes, vitiligo, psoriasis, central nervous system lesions, dental periapical lesions, cerebral palsy, peripheral nerve lesions, especially perinatal brachial plexus palsy, polyneuropathies, amyotrophic lateral sclerosis, spinal muscular atrophy, muscular dystrophies, congenital bone deformations, neuroses, sleep disorders, stress, Attention Deficit Hyperactivity Disorder (ADHD), speech impairment therapy and therapy for children with Down's syndrome. Therefore, this therapy is widely applicable. In the treatment of children, it is indispensible to strictly follow application parameters and observe specifications concerning the size of the area that is exposed to treatment.Conclusions
Magnetoledtherapy is a valuable complement to the comprehensive rehabilitation of children and should be recommended for a wider application.
A monolayer of HeLa cells in plateau-phase of growth was exposed to He-Ne laser radiation either 5 min, 60 min or 180 min before (gamma) -irradiation. It has been shown that in the case of a 5-min interval between the two types of irradiations the survival curve was practically identical to the survival curve of the cells after (gamma) -irradiation only. In the case of He-Ne laser exposure 60 min before (gamma) -irradiation with doses of over 5 Gy, a fraction of more resistant cells was revealed: their D0 was twice as high as the D0 of the min population. A preexposure of cells to He-Ne laser 60 or 180 min before (gamma) - irradiation also changed the shape of the growth curves as compared to (gamma) -irradiated cells. It is proposed that the preexposure of cells to He-Ne laser radiation activates, in a subpopulation of cells, processes which speed up the repair of (gamma) -radiation damage. The possibility that the described phenomenon is an adaptive response of cells is discussed.
We report a 59-year-old Japanese male with diabetic ulcer successfully treated with xenon ray irradiation. The patient, having diabetes mellitus and heart disease, presented with a 1-month history of an unhealed cutaneous ulcer on his left foot. No treatment with topical application was effective. Therefore, xenon ray irradiation was administered. After irradiation was performed with a total dose of 142.7 J/cm2 over a treatment course of 10 weeks, the cutaneous ulcer improved. Xenon ray irradiation has a light source ranging from an ultra-violet wavelength to a near-infrared ray with a peak at 800-900 nm. Xenon ray treatment cutting off the ultra-violet wavelength has been introduced for the control of pain and the rehabilitation of patients with motor disturbances. Near-infrared irradiation is used to promote wound healing. This result indicates that xenon ray irradiation can be valuable for the treatment of cutaneous ulcer in patients with diabetes mellitus.
This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program. LED-technology developed for NASA plant growth experiments in space shows promise for delivering light deep into tissues of the body to promote wound healing and human tissue
growth. We present the results of LED-treatment of cells
grown in culture and the effects of LEDs on patients’ chronic and acute wounds. LED-technology is also biologically optimal for photodynamic therapy of cancer and we discuss our successes using LEDs in conjunction with light-activated chemotherapeutic drugs.
We have developed flexible ZnS:ErF3 alternating current thin film electroluminescent devices on molybdenum foils, and quantified the effect of insulator properties for the case of alumina (Al2O3) and barium tantalate (BaTa2O6) on the device electrical characteristics, and infrared emission. The inverted, full-stack structures could be flexed in tension and compression without mechanical failure or deterioration of optical output, and flex radii of a few centimeters are routinely achieved. Thus, the feasibility of a flexible, inorganic, large area electroluminescent emitter has been demonstrated. Compared to the Al2O3 devices, the numbers for structures employing BaTa2O6 represent a 29% increase in flux density at 980 nm, a 36% increase at 1540 nm, an 18% increase in conduction charge, a 10% increase in phosphor field and a 14% increase in threshold voltage. Our interpretation of the data is as follows: in the case of BaTa2O6, the interface states from which electrons are sourced into the phosphor are deeper, requiring a higher voltage for field emission. As a consequence, electrons are injected into the phosphor when the phosphor field is higher, resulting in better excitation efficiency and improved optical generation. The increase in conduction charge is interpreted as a higher density of interface states, which appear to have a narrower energy distribution based on the more abrupt threshold behavior observed.
The purpose of this study was to evaluate the biological response and gene expression of New Zealand White Rabbit anterior cruciate ligament (ACL) fibroblasts for different wave lengths of light-emitting diode (LED) irradiation. In other words, this study was undertaken to evaluate the effects of different wavelengths of LED irradiation on cell growth, expression of extracellular matrix and growth factors, migration, and expression of actin and integrin. Proliferation assay showed that red (630 nm, 9.5 J/cm(2)) and green LED (530 nm, 9.8 J/cm(2)) irradiated cells were more increased than control group but there was no difference between the control group and the blue LED (460 nm, 27 J/cm(2)) irradiated group. Moreover, the expression of insulin-like growth factor, transforming growth factor-beta (TGF-β1), and collagen I were significantly increased in the red and green LED-irradiated group, but the expression of collagen was decreased in the blue LED-irradiated group. The results of staining showed that collagen and TGF-β1 were weaker in the control group and blue LED-irradiated cells, but stronger in the red and green LED-irradiated cells. Also, in the red and green LED-irradiated group, the expression of actin and integrin was not changed compared to the control group, but the expression of actin and integrin was decreased in the blue irradiated group. This study revealed that irradiation with a wavelength of 460 nm (blue LED) is cytotoxic to ACL cells, but irradiation with nontoxic fluencies of 530 (green LED) and 630 nm (red LED) wavelengths induced cell growth in cultured ACL cells.
Background:
The most common side effects of fractional carbon dioxide (CO2 ) laser resurfacing are erythema and edema of the treated skin. Light-emitting diode (LED) devices have been shown to stimulate fibroblast activity and hasten wound healing. The current study was designed to evaluate the efficacy of such LED devices in treating post-laser therapy erythema.
Objectives:
To evaluate the clinical efficacy of LED photomodulation in reducing erythema resulting from ablative fractional CO2 laser resurfacing.
Materials and methods:
Randomly selected facial halves of 10 Korean subjects (Fitzpatrick skin type III-IV) were treated using a 635-nm wavelength LED array immediately after full-face fractional laser skin resurfacing. Each participant was subsequently treated with LED daily for the following 7 days. Clinical photographs, subjective physician assessment, and chromometer erythema index were used to track the results, with clinical improvement assessed using a 5-point grading scale.
Results:
The postlaser erythema resolved faster on the experimental side than the control side, with improvements noted according to physician assessment and chromometer erythema index. Statistically significant improvements between the two sides were first noted on day 4.
Conclusion:
Treatment using a 635-nm-wavelength LED array decreases the intensity and duration of post-fractional CO2 laser treatment erythema.
Angiogenesis is a key process for wound healing. There are few reports of LED phototherapy on angiogenesis, mainly in vivo. The aim of the present investigation was to evaluate histologically the angiogenesis on dorsal cutaneous wounds treated with laser (660 and 790 nm) or LEDs (700, 530, and 460 nm) in a rodent model. Twenty-four young adult male Wistar rats weighting between 200 and 250 g were used on the present study. Under general anesthesia, one excisional wound was created on the dorsum of each animal that were then randomly distributed into six groups with four animals each: G0-control; G1-laser λ660 nm (60 mW, ϕ ∼2 mm, 10 J/cm(2)); G2-laser λ790 nm (50 mW, ϕ ∼2 mm, 10 J/cm(2)); G3-LED λ700 ± 20 nm (15 mW, ϕ ∼16 mm, 10 J/cm(2)); G4-LED λ530 ± 20 nm (8 mW, ϕ ∼16 mm, 10 J/cm(2)); G5-LED λ460 ± 20 nm (22 mW, ϕ ∼16 mm, 10 J/cm(2)). Irradiation started immediately after surgery and was repeated every other day for 7 days. Animal death occurred at the eighth day after surgery. The specimens were removed, routinely processed to wax, cut and stained with HE. Angiogenesis was scored by blood vessel counting in the wounded area. Quantitative results showed that green LED (λ530 ± 20 nm), red LED (λ700 ± 20 nm), λ790 nm laser and λ660 nm laser caused significant increased angiogenesis when compared to the control group. It is concluded that both laser and LED light are capable of stimulating angiogenesis in vivo on cutaneous wounds and that coherence was not decisive on the outcome of the treatment.
Photobiomodulation with near infrared light (NIR) provides cellular protection in various disease models. Previously, infrared light emitted by a low-energy laser has been shown to significantly improve recovery from ischemic injury of the canine heart. The goal of this investigation was to test the hypothesis that NIR (670 nm) from light emitting diodes produces cellular protection against hypoxia and reoxygenation-induced cardiomyocyte injury. Additionally, nitric oxide (NO) was investigated as a potential cellular mediator of NIR. Our results demonstrate that exposure to NIR at the time of reoxygenation protects neonatal rat cardiomyocytes and HL-1 cells from injury, as assessed by lactate dehydrogenase release and MTT assay. Similarly, indices of apoptosis, including caspase 3 activity, annexin binding and the release of cytochrome c from mitochondria into the cytosol, were decreased after NIR treatment. NIR increased NO in cardiomyocytes, and the protective effect of NIR was completely reversed by the NO scavengers carboxy-PTIO and oxyhemoglobin, but only partially blocked by the NO synthase (NOS) inhibitor L-NMMA. Mitochondrial metabolism, measured by ATP synthase activity, was increased by NIR, and NO-induced inhibition of oxygen consumption with substrates for complex I or complex IV was reversed by exposure to NIR. Taken together these data provide evidence for protection against hypoxia and reoxygenation injury in cardiomyocytes by NIR in a manner that is dependent upon NO derived from NOS and non-NOS sources.
Background:
It is known that while denervated skeletal muscles have the ability to regenerate, maturation of regenerated myofibres does not take place under these conditions. Denervation also causes elevation of "invasive" and satellite cells, but the role of these cells in the regeneration process after injury to the denervated muscle is still unknown. Low energy lasers have recently been found to modulate and accelerate physiological processes in cells. The aim of the present study was to compare regeneration in denervated and innervated amphibian muscles and to investigate whether this process in denervated muscles can be stimulated by low energy laser irradiation prior to injury in these muscles.
Methods:
Denervated gastrocnemius muscles of toads were irradiated with He-Ne laser (6.0 mW, 31.2 J/cm2) 7 days postdenervation (control muscle received red light irradiation at the same wavelength). Nine days after denervation cold injury was performed on the site of irradiation of both groups of muscles. At 14 days postinjury all muscles were removed and processed for histology and histomorphometric analysis of mononucleated cells, myotubes, and young myofibres in the regenerated zone.
Results:
The volume fraction (percent of total injured zone) of the various histological structures in the injured zones 14 days after cold injury in the denervated (9 days prior to injury) muscles did not differ from innervated injured muscles at the same time interval postinjury. The mononucleated cells and myotubes in the laser irradiated muscles comprised 49 +/- 4% and 6 +/- 1% of the injured area, respectively, which was significantly lower than their volume fraction (67 +/- 2% and 11 +/- 2%, respectively) in the control muscles. The young myofibres populated 34 +/- 4% of the total injured area in the denervated and laser irradiated muscles which was significantly higher than their volume fraction (12 +/- 2%) in control denervated muscles.
Conclusions:
It is concluded that initial stages of regeneration can also take place in skeletal denervated and injured muscles of amphibians. The kinetics of the regeneration process are identical in denervated and innervated muscles. The process of regeneration in denervated muscles can be markedly enhanced if the muscle is irradiated by low energy laser prior to injury, probably by activation (stimulation of proliferation and/or differentiation) cells in the muscles that are "recruited" and participate in the process of regeneration.
Background and Objectives
Inhibition of cyclooxygenase (COX) and prostaglandin E2 (PGE2) protects cells against cell injury in specific pathophysiological situations: inflammation and oxidative stress. Although the anti-inflammatory effects have been reported in clinical fields for specific wavelength irradiation during wound healing, the physiological mechanism has not been clarified yet. The aim of the present study is to investigate the anti-inflammatory mechanism of 635 nm light-emitting-diode (LED) irradiation compared with existing COX inhibitors.Study Design/Materials and Methods
The present study investigated anti-inflammatory effects of 635 nm irradiation on PGE2 release, COX and phospholipase A2 (PLA2) expression, and reactive oxygen species (ROS) dissociation in arachidonic acid (AA)-treated human gingival fibroblast (hGF). These results were compared with their existing COX inhibitors: indomethacin and ibuprofen. The PGE2 release was measured by enzyme immunoassay, the COX expression was measured by western blot and reverse transcriptase polymerase chain reaction (RT-PCR), and ROS level was measured by flow cytometry, laser scanning confocal microscope and RT-PCR.ResultsResults showed that 635 nm irradiation and existing COX inhibitors inhibit expression of COX and PGE2 release. Unlike indomethacin and ibuprofen, 635 nm irradiation leads to a decrease of ROS levels and mRNA expression of cytosolic phospholipase A2 (cPLA2) and secretary phospholipase A2 (sPLA2).Conclusion
Taken together, 635 nm irradiation, unlike indomethacin and ibuprofen, can directly dissociate the ROS. This inhibits cPLA2, sPLA2, and COX expression, and results in the inhibition of PGE2 release. Thus, we suggest that 635 nm irradiation inhibits PGE2 synthesis like COX inhibitor and appears to be useful as an anti-inflammatory tool. Lesers Surg. Med. 39:614–621, 2007. © 2007 Wiley-Liss, Inc.
We previously reported that 710 nm Light-emitting Diode (LED) has a protective effect through cellular immunity activation in the stroke animal model. However, whether LED directly protects neurons suffering from neurodegeneration was entirely unknown. Therefore, we sought to determine the effects of 710 nm visible light irradiation on neuronal protection and neuronal outgrowth in an in vitro stroke model.
Primary cultured rat cortical neurons were exposed to oxygen-glucose deprivation (OGD) and reoxygenation and normal conditions. An LED array with a peak wavelength of 710 nm was placed beneath the covered culture dishes with the room light turned off and were irradiated accordingly. LED treatments (4 min at 4 J/cm(2) and 50 mW/cm(2)) were given once to four times within 8h at 2h intervals for 7 days. Mean neurite density, mean neurite diameter, and total fiber length were also measured after microtubule associated protein 2 (MAP2) immunostaining using the Axio Vision program. Synaptic marker expression and MAPK activation were confirmed by Western blotting.
Images captured after MAP2 immunocytochemistry showed significant (p<0.05) enhancement of post-ischemic neurite outgrowth with LED treatment once and twice a day. MAPK activation was enhanced by LED treatment in both OGD-exposed and normal cells. The levels of synaptic markers such as PSD 95, GAP 43, and synaptophysin significantly increased with LED treatment in both OGD-exposed and normal cells (p<0.05).
Our data suggest that LED treatment may promote synaptogenesis through MAPK activation and subsequently protect cell death in the in vitro stroke model.