Photobiomodulation at 660 nm promotes collagen synthesis via downregulation of HIF-1α expression without photodamage in human scleral fibroblasts in vitro in a hypoxic environment.

PURPOSE: The increasing prevalence of myopia is a global public health issue. Because of the complexity of myopia pathogenesis, current control methods for myopia have great limitations. The aim of this study was to explore the effect of photobiomodulation (PBM) on human sclera fibroblasts (HSFs) under hypoxia, in the hope of providing new ideas for myopia prevention and control. METHODS: Hypoxic cell model was established at 0, 6, 12, and 24 h time points to simulate myopia microenvironment and explore the optimal time point. Control, hypoxia, hypoxia plus light, and normal plus light cell models were set up for the experiments, and cells were incubated for 24 or 48 h after PBM (660 nm, 5 J/cm2), followed by evaluation of hypoxia-inducible factor 1α (HIF-1α) and collagen I a1 (COL1A1) proteins using Western blotting and immunofluorescence, and photo damage was detected by CCK-8, scratch test, and flow cytometry assays. We also used transfection technology to further elucidate the regulatory mechanism. RESULTS: The change of target proteins is most obvious when hypoxia lasts for 24 h (p < 0.01). PBM at 660 nm increased extracellular collagen content (p < 0.001) and downregulated expression of HIF-1α (p < 0.05). This treatment did not affect the migration and proliferation of cells (p > 0.05), and effectively inhibited apoptosis under hypoxia (p < 0.0001). After overexpression of HIF-1α, the effect of PBM was attenuated (p > 0.05). CONCLUSIONS: Photobiomodulation at 660 nm promotes collagen synthesis via downregulation of HIF-1α expression without photodamage.

Chronic red laser treatment induces hypotensive effect in two-kidney one-clip model of renovascular hypertension in rat.

To evaluate whether the chronic effect of photobiomodulation therapy (PBM) on systolic arterial pressure (SAP) from two kidneys one clip (2 K-1C) hypertension animal models can cause a hypotensive effect. Serum levels of nitric oxide were also analyzed and the assessment of lipid peroxidation of the thoracic aorta artery. Male Wistar rats were used. Hypertensive animals (2 K-1C) with Systolic arterial pressure (SAP) greater than or equal to 160 mmHg were used. Systolic arterial pressure (SAP) was determined by the tail plethysmography technique. Normotensive (2 K) and hypertensive (2 K-1C) rats were treated to PBM for 4 weeks using a laser whose irradiation parameters were: red wavelength (λ) = 660 nm: operating continuously; 56 s per point (3 points) spot size = 0.0295 cm2; average optical power of 100 mW; energy of 5.6 J per point; irradiance of 3.40 W/cm2; fluency of 190 J/cm2 per point. The application was on the animals tails, at 3 different points simultaneously, in contact with the skin. To assess serum nitrite and nitrate (NOx) levels, blood collection was performed after chronic PBM treatment, 24 h after the last laser application. The evaluation of the lipid peroxidation of the thoracic aorta artery was performed by measuring the concentration of hydroperoxide by the FOX method. Chronic photobiomodulation therapy (PBM) by red laser (660 nm) can induce a hypotensive effect in 64% of 2 K-1C hypertensive animals, which we say responsive animals. There was no difference in serum NO levels 24 h after the last red laser application, between treated and non-treated groups. Aortic rings from 2 K-1C hypertensive animals present a higher lipid peroxidation. The chronic PBM treatment by red laser decreased aortic rings lipid peroxidation in hypertensive responsive groups, compared to control. our results indicate that chronic PBM made by red laser has an important hypotensive effect in renovascular hypertensive models, by a mechanism that involves decrease in oxidative stress from vascular beds.

Photobiomodulation Response From 660 nm is Different and More Durable Than That From 980 nm.

BACKGROUND AND OBJECTIVES: Photobiomodulation (PBM) therapy uses light at various wavelengths to stimulate wound healing, grow hair, relieve pain, and more-but there is no consensus about optimal wavelengths or dosimetry. PBM therapy works through putative, wavelength-dependent mechanisms including direct stimulation of mitochondrial respiration, and/or activation of transmembrane signaling channels by changes in water activity. A common wavelength used in the visible red spectrum is ~660 nm, whereas recently ~980 nm is being explored and both have been proposed to work via different mechanisms. We aimed to gain more insight into identifying treatment parameters and the putative mechanisms involved. STUDY DESIGN/MATERIALS AND METHODS: Fluence-response curves were measured in cultured keratinocytes and fibroblasts exposed to 660 or 980 nm from LED sources. Metabolic activity was assessed using the MTT assay for reductases. ATP production, a major event triggered by PBM therapy, was assessed using a luminescence assay. To measure the role of mitochondria, we used an ELISA to measure COX-1 and SDH-A protein levels. The respective contributions of cytochrome c oxidase and ATP synthase to the PBM effects were gauged using specific inhibitors. RESULTS: Keratinocytes and fibroblasts responded differently to exposures at 660 nm (red) and 980 nm (NIR). Although 980 nm required much lower fluence for cell stimulation, the resulting increase in ATP levels was short-term, whereas 660 nm stimulation elevated ATP levels for at least 24 hours. COX-1 protein levels were increased following 660 nm treatment but were unaffected by 980 nm. In fibroblasts, SDH-A levels were affected by both wavelengths, whereas in keratinocytes only 660 nm light impacted SDH-A levels. Inhibition of ATP synthase nearly completely abolished the effects of both wavelengths on ATP synthesis. Interestingly, inhibiting cytochrome c oxidase did not prevent the rise in ATP levels in response to PBM treatment. CONCLUSION: To the best of our knowledge, this is the first demonstration of differing kinetics in response to PBM therapy at red versus NIR wavelength. We also found cell-type-specific differences in PBM therapy response to the two wavelengths studied. These findings confirm that different response pathways are involved after 660 and 980 nm exposures and suggest that 660 nm causes a more durable response. © 2021 Wiley Periodicals LLC.

Consequences of 660 nm Diode Laser Following Postsurgical Exodontia in Patients under Contraceptive Pills: A Randomized Double-blinded Clinical Trial.

AIM: The photobiomodulation (PBM) effect of 660 nm diode laser in reducing pain, edema, trismus and promote healing subsequently to the transalveolar extraction of mandibular third molars in female patients taking contraceptive pills were evaluated. MATERIALS AND METHODS: Fifty female patients participated in our study. The 660 nm diode laser was applied immediately on randomly selected patients of the study group (n = 25) over the surgical site for 1 minute with continuous laser beam application. For the control group (n = 25), the same extraction procedure was performed without the application of 660 nm diode laser. Pain intensity, swelling, trismus, and healing was evaluated before extraction and during recall visits 24 hours, 48 hours, and 7 days postoperatively. RESULTS: The values of pain, swelling, and trismus were significantly inferior in the study group compared to the control group (p < 0.05) at T2 and T3; while the values of the healing index were significantly superior in the study group compared to the control group (p < 0.001) at T1, T2, and T3. CONCLUSION: Using 660 nm diode laser reduced the postsurgical discomforts (pain, edema, and trismus) and promote healing associated following transalveolar extraction of the lower third molar. CLINICAL SIGNIFICANCE: To develop a framework based on the results regarding the PBM effect of 660 nm diode laser following transalveolar extraction of lower third molar in a female patient taking oral contraceptive pills, which may help to improve the treatment services provided to the community.

Inhibitory effect of 660-nm LED on melanin synthesis in in vitro and in vivo.

BACKGROUND: Skin hyperpigmentary disorders including postinflammatory hyperpigmentation, melasma, solar lentigines, and conditions like freckles are common. The light-emitting diodes (LEDs) are the latest category of nonthermal and noninvasive phototherapy to be considered in skin pigmentation disorder treatment. PURPOSE: The purpose of this study was to investigate the effects of 660-nm LED on inhibition of melanogenesis. We investigated whether a 660-nm LED affected melanin synthesis in in vitro and in vivo models, and we explored the mechanisms involved. METHODS: The inhibitory effect of 660-nm LED on melanin synthesis was evaluated in B16F10 cells and HRM-2 melanin-possessing hairless mice were used to evaluate the antimelanogenic effects of 660-nm LED. RESULTS: Interestingly, 660-nm LED inhibited alpha-melanocyte-stimulating hormone-induced tyrosinase activity in B16F10 cells. We also found that 660-nm LED decreased MITF and tyrosinase expression and induced the activation of ERK. These findings suggest that the depigmenting effects of 660-nm LED result from downregulation of MITF and tyrosinase expression due to increased ERK activity. The 660-nm LED reduced UVB-induced melanogenesis in the skin of HRM-2 via downregulation of tyrosinase and MITF. CONCLUSION: These findings suggest 660-nm LED is a potentially depigmentation strategy.

Enhanced quantification of chlorophyll a and its degradation products in olive oil using time-resolved laser-induced fluorescence fingerprint analysis.

Potential errors in the fluorescence analysis of chlorophylls and their degradation products, primarily due to spectral overlap and inner filter, are widely acknowledged. This study aimed to devise a sensitivity-enhanced technique for the concurrent quantification of chlorophyll a and its degradation products while minimizing effects from type-B chlorophylls. Initially, a time-resolved laser-induced fluorescence spectroscopic system was designed and tested on stardard chlorophyll samples. The origins, implications, and mitigation strategies of spectral overlap and the inner filter effect on the measured fluorescence intensity were thoroughly examined. Then, this methodology was proved to be efficacious within complex liquid matrices derived from olive oil. The experimental outcomes not only shed additional light on the mechanisms of chlorophyll fluorescence overlap and the inner filter effect, but also establish a general framework for developing spectrally and timely resolved fluorescence fingerprint analysis for the simultaneous quantification of chlorophylls and their degradation products at high concentrations.

In vitro study on the effects of photodynamic inactivation using methyl pheophorbide a, PhotoMed, PhotoCure, and 660 nm diode laser on Candida albicans.

BACKGROUND: Candida albicans (C. albicans) is the most common fungal pathogen that causes clinical infections in humans. This study aimed to evaluate the effects of photodynamic inactivation (PDI) using a 660 nm diode laser along with methyl pheophorbide a, PhotoMed, and PhotoCure as photosensitizer for analyzing the viability of in vitro inactivation of C. albicans Methods: In the PDI group, 20 µL of C. albicans suspension and 20 µL of photosensitizer were inoculated in a 90 mm petri dish (63.6 cm2). The samples were placed in an incubator at 37 °C for 30 min, and then they were irradiated with light (660 nm diode laser, 3 J/cm2). After laser irradiation, the cells were stored for 48 h at 37 °C in an incubator with 5% CO2, and the number of colonies was counted. RESULTS: The highest reduction in the number of colony-forming units per milliliter (CFU/mL) after PDI was observed in the presence of methyl pheophorbide a and PhotoMed, followed by PhotoCure. One-way analysis of variance (ANOVA) demonstrated a significant inhibition (F = 384.717; P < 0.05) for each PDI. CONCLUSIONS: In this study, we demonstrated that the application of PDI to C. albicans using methyl pheophorbide a and PhotoMed resulted in 100% death rates. PDI could be a treatment method because conventional antifungals have limited effects, and they may not eliminate C. albicans completely.

TB@PLGA Nanoparticles for Photodynamic/Photothermal Combined Cancer Therapy with Single Near-Infrared Irradiation.

BACKGROUND: Phototherapy has significant potential as an effective treatment for cancer. However, the application of a multifunctional nanoplatform for photodynamic therapy (PDT) and photothermal therapy (PTT) at a single excitation wavelength remains a challenge. MATERIALS AND METHODS: The double emulsion solvent evaporation method was used to prepare toluidine blue@poly lactic-co-glycolic acid (TB@PLGA) nanoparticles (NPs). The biocompatibility of TB@PLGA NPs was evaluated, and a 660 nm luminescence was used as the light source. The photothermal effect, photothermal stability, and singlet oxygen yield of NPs in an aqueous solution verified the feasibility of NPs as a PTT/PDT synergistic therapy drug. RESULTS: TB@PLGA NPs were successfully prepared and characterized. In vitro experiments demonstrated that TB@PLGA NPs can cause massive necrosis of tumor cells and induce apoptosis through a photodynamic mechanism under 660 nm laser irradiation. The TB@PLGA NPs also achieved optimal tumor inhibition effect in vivo. CONCLUSION: The TB@PLGA NPs prepared in this study were applied as a dual-mode phototherapeutic agent under single laser irradiation. Both in vitro and in vivo experiments demonstrated the good potential of PTT/PDT for tumor inhibitors.

Synergistic effects of using novel home-use 660- and 850-nm light-emitting diode mask in combination with hyaluronic acid ampoule on photoaged Asian skin: A prospective, controlled study.

BACKGROUND: Recently, light-emitting diode (LED) devices are among those mostly preferred for esthetic application because they improve the appearance of photoaged skin characterized by wrinkles, sagginess, pigmented lesions, and others. In addition, the use of hyaluronic acid (HA) for skin rejuvenation is already well proven. AIMS: This study aims to evaluate the synergistic effects of using home-use LED mask device with HA ampoule. METHODS: The total number of recruited subjects was 48:24 in Group A treated with both home-use LED mask device and HA ampoule and 24 in Group B treated with HA ampoule only, for 4 weeks. To assess the efficacy of the treatment, the following were used: Antera 3D CS, EOS 800D with Image-Pro Plus, DUB-USB, VisioFace Quick, and Visioscan VC98. RESULTS: After treatment, the volume measurement (mm3 ) for prejowl sulci and nasolabial fold flattening as well as the area measurement (pixel) for lower chin firmness improvement was significantly reduced, and the number of pores (ea) for enlarged pores as well as the desquamation index (%) for the amount of corneocytes significantly decreased in both Group A and Group B. Moreover, the percentage of skin density significantly improved. Furthermore, Group A showed a significantly faster and higher rate of improvement than Group B. CONCLUSION: The use of 660- and 850-nm home-use LED mask device can generate synergistic effects on home-use topical applications like HA on photoaged face, and such device can be safely and efficiently used daily in personal environments.

Effect of Photobiomodulation Therapy (660 nm) on Wound Healing of Rat Skin Infected by Staphylococcus.

Objective: To assess the impact of photobiomodulation (PBM) therapy on healing of infected wounds and document the microscopic findings throughout the recovery process. Background: Previous studies have suggested that PBM accelerates wound healing and reduces inflammation and pain. However, the ideal protocol and ultimate value of PBM treatment for infected wounds are controversial. Materials and methods: Eight-month-old male rats were randomly divided into the control group, the nonirradiation group, or the irradiation group. A 1 cm diameter skin excision was made. The wounds of the nonirradiated and irradiated rats were inoculated with a suspension of Staphylococcus aureus. We then performed 7 days of PBM therapy at a wavelength of 660 nm for 35 min/day. On day 8, the rats were sacrificed for histological assessment. Sections were stained with hematoxylin and eosin, Masson trichrome, and a proliferating cell nuclear antigen (PCNA) kit. Defect diameter was calculated using the Visus Image Analysis System. Results: The irradiated group had more epithelial cells and richer granulation tissue compared to those in the other groups. The irradiation group had a significantly smaller defect size than the nonirradiation group (p < 0.01) and the control group (p < 0.05). The amount of collagen was highest in the irradiation group and was graded as 3, 2, and 3+ in the control, nonirradiation, and irradiation groups, respectively. The percentage of PCNA in the control group was significantly lower than that in the other two groups (p < 0.05). Conclusions: PBM therapy (660 nm) promoted cell proliferation and collagen synthesis, thereby improving the wound healing response to an S. aureus infection.

Effect of antimicrobial photodynamic therapy with Radachlorin and a 660 nm diode laser on Pseudomonas aeruginosa: An in vitro study.

BACKGROUND: Pseudomonas aeruginosa is one of the most life-threatening pathogens in nosocomial environments. This study aimed to explore whether photodynamic therapy using a 660 nm diode laser and Radachlorin is an effective in vitro inhibitor of P. aeruginosa and determine what energy density and rate of delivery are the most impactful. METHODS: Suspensions ofP. aeruginosa were obtained, inoculated in petri dishes with Radachlorin, and incubated for 30 min. Then, the laser light of a 660 nm diode laser was irradiated at varying energy densities and rates of delivery. Cell viability was evaluated after culturing. RESULTS: The combination of Radachlorin and the laser was more effective than Radachlorin or the laser alone (P < 0.05) in reducingP. aeruginosa and showed a killing rate of 95.8 % at an energy density of 5 J/cm2. In addition, the low rate of photodynamic therapy delivery group was more effective in inhibiting P. aeruginosa compared to the high rate of photodynamic therapy delivery group (P < 0.05). CONCLUSIONS: Within the limitations of thisin vitro study, we found that photodynamic therapy using a 660 nm diode laser and Radachlorin was effective for the inhibition of P. aeruginosa. In addition, energy density and rate of delivery are important factors to consider when using a 660 nm diode laser and Radachlorin to inhibit the growth of this organism.

Clinical Evaluation of 660 nm Diode Laser Therapy on the Pain, Size and Functional Disorders of Recurrent Aphthous Stomatitis.

BACKGROUND: Minor recurrent aphthous stomatitis (MiRAS) is one of the most common, recurrent, and painful mucosal pathological condition. It is characterised by round or shallow oval ulcers, less than 10 mm in diameter, surrounded by a thin erythematous halo. It involves non-keratinized mucosa such as the labial and buccal mucosa, the ventral surface or borders of the tongue and the floor of the mouth, but it is uncommon to occur on the keratinised mucosa. It heals spontaneously within 10-14 days without scarring. There is no curative remedy to prevent its recurrence; also, available modalities only reduce the symptoms and severity of the lesion. AIM: Since these lesions may be extremely painful, we decided to estimate the pain-relieving and healing properties of low energy level laser therapy using diode laser 660 nm on MiRAS. MATERIAL AND METHODS: Twenty healthy patients suffering from minor aphthous ulcers were randomly selected from the Out-Patient Clinic of Oral Medicine Department, Faculty of Dentistry, Alexandria University. They were equally divided into two groups, study group who received 660 nm diode laser irradiation while the control group received placebo (sodium bicarbonate rinse). The visual analogue scale, size reduction, effectiveness indices and functional disorders were compared between the groups. RESULTS: Both groups presented a statistically significant difference from baseline to follow up periods. But, diode laser 660 nm treatment showed more remarkable improvements in reduction of healing time, pain and lesion size. CONCLUSION: We concluded that diode laser 660 nm should be further considered as an effective alternative therapeutic regimen to patients who suffer from recurrent aphthous stomatitis.

Effect of low-level laser irradiation on proliferation of human dental mesenchymal stem cells; a systemic review.

CONTEXT: Identification of factors that enhance the proliferation of human dental mesenchymal stem cells (DMSCs) is vital to facilitate tissue regeneration. The role of low-level laser irradiation (LLLI) on proliferation of human DMSCs has not been well established. OBJECTIVE: To assess the effect of LLLI on proliferation of human DMSCs when applied in-vitro. DATA SOURCES: Electronic search of literature was conducted (2000-2016) on PubMed, Web of Science, and Scopus databases. Search terms included low-level light therapy, low-level laser irradiation, low-level light irradiation, LLLT, humans, adolescent, adult, cells, cultured, periodontal ligament, dental pulp, stem cells, dental pulp stem cells, mesenchymal stem cells, periodontal ligament stem cell, deciduous teeth, cell proliferation, adult stem cells, radiation, and proliferation. RESULTS: The literature search identified 165 studies with 6 being eligible for inclusion; all used diode lasers; 5 studies used InGaAIP diode lasers; 4 used 660nm, and the other two applied 810nm or 980nm wavelength LLLI. The distance between the DMSCs and the laser spot ranged between 0.5mm to 2mm. The time intervals of cell proliferation analysis ranged from 0h to 7days after LLLI. After 660nm LLLI, an increase in the DMSC's proliferation was reported [DMSCs extracted from dental pulp of deciduous teeth (two irradiations, 3J/cm(2), 20mW was more effective than 40mW), adult teeth (two irradiations, 0.5 and 1.0J/cm(2), 30mW), and from adult periodontal ligament (two irradiations, 1.0J/cm(2) was more effective than 0.5J/cm(2), 30mW)]. Similarly, an increase in the proliferation of DMSCs extracted from dental pulp of adult teeth was reported after 810nm LLLI (7 irradiations in 7days, 0.1 and 0.2J/cm(2), 60mW) or 980nm LLLI (single irradiation, 3J/cm(2), 100mW). However, 660nm LLLI in one study did not increase the proliferation of DMSCs (single irradiation, energy densities of 0.05, 0.30, 7, and 42J/cm(2), 28mW). CONCLUSION: There is limited evidence that in-vitro LLLI (660/810/980nm, with energy densities of 0.1-3J/cm(2)) increases the proliferation of DMSCs. Considering the limited evidence and their method heterogeneity it is difficult to reach a firm conclusion. Further research is necessary to identify the optimal characteristics of the LLLI setting (wave length, energy density, power output, frequency/duration of irradiations, distance between the cells and the laser spot/probe) to increase proliferation of DMSCs, and assess its impact on replicative senescence, as well as determine feasibility of the use in the clinical setting.