Biphasic dose response in low level light therapy

Comparative efficacy of minoxidil alone versus minoxidil combined with low-level laser therapy in the treatment of androgenic alopecia: a systematic review and meta-analysis

OBJECTIVE

This systematic review evaluates the efficacy of minoxidil alone versus minoxidil with low-level laser therapy (LLLT) for androgenic alopecia.

STUDY DESIGN

systematic review and meta-analysis.

METHODS

An online search of PubMed, Web of Science, and MEDLINE was conducted. Randomized clinical trials comparing minoxidil monotherapy with minoxidil and LLLT combination therapy were included based on predefined criteria. The Risk of Bias 2.0 (RoB 2.0) tool was used for quality assessment.

RESULTS

From 38 identified studies, 34 remained after excluding 4 duplicates. Further exclusions left 4 eligible studies comparing minoxidil alone with minoxidil and LLLT. The meta-analysis found no statistically significant differences in hair counts between the two groups at baseline, 12 weeks, and 8 weeks post-treatment [mean difference = -0.04, 95% CI -1.22 to 1.14, p = .95, I² = 0%]. Similarly, hair diameter showed no significant differences at the same time points [mean difference = 0.00, 95% CI -0.00 to 0.00, p = .98, I² = 38%].

CONCLUSION

The combination of minoxidil and LLLT does not significantly improve outcomes compared to minoxidil alone for treating androgenic alopecia.

Flexible, surface-lighting MicroLED skin patch for multiple human skincare

As the global population ages, concerns regarding aesthetic appearance have increased. Wearable light-emitting diode (LED) devices have received significant attention in the cosmetic fields due to their non-invasive, non-thermal, home-use characteristics. However, conventional bulk LED chips have limitations in flexibility and uniform irradiation, hindering efficient light penetration into the skin. Here, we introduce a flexible, surface-lighting microLED (FSLED) patch with uniform light-emission for various skincare applications. The FSLED was fabricated using a pick-and-place transfer technique, which allows for high-density irradiation over the large area, while maintaining outstanding mechanical flexibility. In addition, the FSLED was designed to deliver light efficiently and emit light evenly by conforming to the skin. Finally, we prove the effect of the FSLED for pore tightening and skin rejuvenation through clinical trials.

Adjuvant Effect of Photobiomodulation in the Pain Relief and Healing of Ulcerative Lesions from Mammary Tuberculosis

This case report describes the use of photobiomodulation (PBM) as a complementary therapy in a 45-year-old patient with mammary tuberculosis (TB). The patient received conventional treatment, including antibiotic therapy and analgesics. Three months after the diagnosis, breast pain persisted (Visual Analog Scale [VAS] score: 8), and the mammary lesions had not healed. Adjuvant treatment with PBM (660 nm and 808 nm lasers, 100 mW, 3,333 mW/cm2, 20 J per session) was performed over 12 sessions in 38 days. After four PBM sessions, the patient reported no pain (VAS score: 0) and stopped using analgesics. Complete healing of the mammary lesions was observed after 12 sessions. The use of PBM was associated with improvements in tissue repair, pain control, and healing of lesions resulting from mammary TB.

Evaluating the Preclinical Efficacy of Photobiomodulation in Alleviating Neuropathic Corneal Pain: A Behavioral Study

Purpose

Neuropathic corneal pain (NCP) is a debilitating condition characterized by persistent pain due to corneal nerve damage or dysfunction. Millions of individuals and their families endure the significant impact of chronic pain. Effective management strategies are crucial yet limited, prompting the exploration of innovative treatments such as photobiomodulation (PBM).

Design

In vivo preclinical therapeutics investigation in mice.

Subjects

Thy1-YFP mice.

Methods

This study evaluates the efficacy of PBM in treating NCP across 4 animal models: normal control, sham control, pulled nerve, and full transection (FT). Behavioral assessments, including the von Frey test (VFT) for mechanical sensitivity and the eye-wiping test (EWT) for chemical sensitivity, were employed to evaluate the therapeutic impact of PBM till day 56 (D-1, D1, D3, D5, D7, D14, D28, D42, and D56).

Main Outcome Measures

Advances in therapeutic approach for NCP through the potential of PBM.

Results

Photobiomodulation significantly reduced behavioral manifestations of pain in the pulled nerve model (VFT: no PBM [D1 = 0.043 ± 0.044, D56 = 0.05 ± 0.014] and PBM [D1 = 0.050 ± 0.008 {P value = 0.18}, D56 = 0.09 ± 0.014 {P value = 0.02}], EWT: no PBM [D1 = 11.96 ± 0.47, D56 = 12.11 ± 0.15] and PBM [D1 = 11.73 ± 0.18 {P value = 0.2}, D56 = 11.22 ± 0.31] [P value = 0.01]) and FT model (VFT: no PBM [D1 = 0.022 ± 0.0028, D56 = 0.023 ± 0.0047] and PBM [D1 = 0.024 ± 0.0028 {P value = 0.2}, D56 = 0.073 ± 0.0094] [P value = 0.02]), EWT: no PBM [D1 = 13.1 ± 0.14, D56 = 13.36 ± 0.30] and PBM [D1 = 12.86 ± 0.41, {P value = 0.2}, D56 = 12.53 ± 0.41] [P value = 0.04]}, suggesting an effective reduction of pain sensitivity and an increase in corneal nerve function. The temporal patterns also suggest that early intervention with PBM, initiated shortly after nerve injury, may be crucial for preventing the chronic progression of NCP.

Conclusions

These outcomes support PBM as a promising nonpharmacologic intervention for NCP; this not only reinforces the potential of PBM in NCP treatment but also provides a foundation for future clinical applications in managing corneal neuropathy.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Interfacial water engineering for enhanced pure water electrolysis

We report the development of a novel self-organized water (SOW) electrolyzer using a plasma electrolytic oxidation (PEO)-treated platinum-titanium (PEO-Pt/Ti) heterostructure electrode, demonstrating exceptional performance in the hydrogen evolution reaction (HER). Hydrophilic materials like Nafion are critical for forming interfacial water zones with distinct properties compared to bulk water. We investigated the effects of infrared (IR) light on the negatively charged SOW and positively charged protonated water (PW) near Nafion surfaces. Mid-IR irradiation for 13 min significantly expanded the SOW, enhancing its ability to facilitate the dissociation of interfacial water into hydroxide ions (OH⁻) and protons (H⁺), thus driving efficient water splitting. The PEO-Pt/Ti electrode, synergized with optimized SOW, modulates electronic states, increases active surface area, improves conductivity, and lowers activation energy barriers. This enables current densities of 100 mA cm⁻² at 3.1 V and superior H₂ production at 3.5 V, with stable operation exceeding 25 h. These findings highlight the system's durability, efficiency, and cost-effectiveness. By integrating advanced electrode engineering with SOW systems, this work introduces a scalable strategy for sustainable hydrogen production, addressing key challenges in clean energy generation and advancing renewable energy technologies.

Immunomodulatory effects of photobiomodulation: a comprehensive review

Photobiomodulation, also known as low-level light therapy (LLLT), has emerged as a promising non-invasive treatment modality with significant immunomodulatory effects. This comprehensive review examines the mechanisms underlying photobiomodulation-induced immunomodulation, its effects on specific immune cells, and its clinical applications in immune-related conditions. We explore the cellular and molecular pathways affected by photobiomodulation, including mitochondrial function, reactive oxygen species production, and key signaling cascades. The impact of photobiomodulation on macrophages, T cells, and dendritic cells is discussed, along with its potential in managing autoimmune diseases, inflammatory conditions, and wound healing. Safety considerations, optimal treatment parameters, and future directions in the field are also addressed. This review highlights the growing body of evidence supporting photobiomodulation as a valuable tool in immunomodulation and its potential to revolutionize the treatment of various immune-mediated disorders.

A Pilot Study Comparing Intraoral and Transcutaneous Photobiomodulation for Oral Mucositis in Head and Neck Cancer Patients Undergoing Radiotherapy or Chemoradiotherapy

Background: Photobiomodulation (PBM) therapy has shown potential in managing oral mucositis (OM), a frequent and painful side effect of radiotherapy or chemoradiotherapy in head and neck cancer patients. Although PBM is increasingly used in clinical settings, the optimal delivery method-transcutaneous or intraoral-remains undetermined. Methods: This prospective, single-center, randomized pilot study (clinicaltrials.gov NCT06458517) aims to compare the efficacy of transcutaneous versus intraoral PBM in preventing and managing OM in patients undergoing radiotherapy or chemoradiotherapy for cancers of the oral cavity or oropharynx. Participants will be randomized into two groups: one receiving intraoral PBM with the CareMin650™ device, and the other receiving transcutaneous PBM with the ATP38® device. Results: Primary and secondary outcomes will include the incidence and severity of OM, treatment interruptions, patient-reported pain levels, and quality of life, assessed using validated tools. Conclusions: This study will provide comparative data on two PBM modalities, contributing to the development of standardized PBM protocols in supportive oncology care and informing future multicenter trials aimed at improving patient outcomes during radiotherapy for head and neck cancer.

Comparative efficacy of low-level diode laser therapy with different wavelengths in burning mouth syndrome: a randomized, single-blind trial

Burning mouth syndrome (BMS) is a chronic condition with no effective treatment currently available. Low-level laser therapy (LLLT) shows promise for neuropathic pain management, but evidence comparing its efficacy across different wavelengths in BMS patients remains limited. This study aimed to assess the clinical efficacy of LLLT with three distinct wavelengths in BMS patients, and to determine the optimal therapeutic wavelength. This study was a single-blind randomized controlled trial, with blinding applied only to the participants. 201 participants were scheduled for enrollment, divided into three groups with 67 individuals each. Finally, 63 participants with BMS were enrolled from April 2019 to December 2022, with 53 completing the study. Randomization was performed using SPSS software to generate random numbers. Participants were sequentially assigned based on their enrollment order to the 660 nm group (n = 10, 50 mW, 1.5 J/cm2, 30 s/point), 810 nm group (n = 26, 500 mW, 3 J/cm2, 6 s/point), or 975 nm group (n = 17, 30 mW, 10 J/cm2, 33 s/point). Each participant underwent LLLT once a week for 4 sessions. Outcomes, including pain intensity, numbness, and altered taste, were assessed using the visual analogue scale (VAS). Efficacy was assessed by comparing VAS scores at baseline and after the last treatment, using the Kruskal-Wallis test for comparisons among the three groups and the Mann-Whitney U-test for pairwise analysis. Effect sizes were reported using Cohen's d. Statistically significant pain relief was observed in all groups (median reduction of 40%). The improvement of numbness in the 810 nm and 975 nm groups (median reduction of 40%) was also significant (p < 0.05). However, no significant differences in efficacy were noted among the three groups (p > 0.05). These results suggested that LLLT with three different wavelengths effectively reduced pain and that the 810 nm and 975 nm wavelengths also significantly alleviated numbness in BMS patients. However, further investigation is warranted to elucidate any potential differences in efficacy among the three groups. Clinical trial registration: ChiCTR1900021674 (March 5, 2019).

Newly Designed Organic-Inorganic Nanocomposite Membrane for Simultaneous Cr and Mn Speciation in Waters

A sol-gel approach was used to prepare a thin hydrogel membrane based on an organic-inorganic polymer matrix embedded with pre-synthesized gold nanoparticles (AuNPs). The organic polymers utilized were poly(vinyl alcohol) (PVA) and poly(ethylene oxide) 400 (PEO) while tetraethoxysilane (TEOS) served as a precursor for the inorganic silica polymer. AuNPs were synthesized using D-glucose as a reducing agent and starch as a capping agent. A mixture of PVA, PEO, pre-hydrolyzed TEOS, and AuNP dispersions was cast and dried at 50 °C to obtain the hybrid hydrogel membrane. The structure, morphology, and optical properties of the nanocomposite membrane were analyzed using TEM, SEM, XRD, and UV-Vis spectroscopy. The newly designed hybrid hydrogel membrane was utilized as an efficient sorbent for the simultaneous speciation analysis of valence species of chromium and manganese in water samples via solid-phase extraction. This study revealed that Cr(III) and Mn(II) could be simultaneously adsorbed onto the PVA/PEO/SiO2/AuNP membrane at pH 9 while Cr(VI) and Mn(VII) remained in solution due to their inability to bind under these conditions. Under optimized parameters, detection limits and relative standard deviations were determined for chromium and manganese species. The developed analytical method was successfully applied for the simultaneous speciation analysis of chromium and manganese in drinking water and wastewater samples.

Clinical and Microbiological Effectiveness of Diode Laser for Treating Patients with Stage II Grade A Periodontitis Patients: Split-Mouth Study

Objectives: This split-mouth randomized controlled clinical trial aimed to evaluate the efficacy of diode laser therapy as an adjunct to scaling and root planning (SRP) in the management of patients with stage II grade A periodontitis. Methods: Thirty participants were randomly assigned to receive either SRP alone (control group) or SRP and diode laser application (study group) on the contralateral side. Clinical parameters (plaque index, gingival index, probing depth, and clinical attachment level) and microbiological markers; Aggregatibacter actinomycetemcomitans (A actinomycetemcomitans), Porphyromonas gingivalis (P gingivalis), and Fusobacterium nucleatum (F nucleatum) were evaluated at baseline and at 4, 8, and 12 weeks post-treatment. Results: Both groups reported significant improvements in all clinical parameters over the follow-up period. The study group reported a significantly higher reduction in probing depth at 12 weeks than the SRP-alone group. Microbiological evaluation revealed significantly greater reductions in P gingivalis and F. nucleatum levels in the study group at later time points, whereas no significant alterations were observed for A actinomycetemcomitans. Conclusions: Our results suggest that the adjunctive use of diode laser therapy may improve the clinical and microbiological findings of nonsurgical periodontal management in patients with stage II grade A periodontitis.

Absorption Coefficient Estimation of Pigmented Skin Phantoms Using Colorimetric Parameters

The increasing use of light-based treatments requires a better understanding of the light tissue interaction for pigmented skin. To enhance comprehension in this area, this study proposes the use of pigmented-mimicking skin phantoms to assess the optical properties based on their tone, represented by the individual typology angle (ITA) color scale. In this study, an epoxy resin matrix alongside compact facial powder and titanium dioxide was used to mimic the absorption, scattering, and shade properties of human skins. Eight phantoms covering the skin tones, light (ITA = 45.2°), tan (ITA = 23.3°), brown (ITA = 6.9°, -5.7°, and -16.9°), and dark (ITA = -34.6°, -41.6°, and -48.6°), were crafted. The absorption and reduced scattering coefficients were obtained using integrating spheres and calibrated spectrometers in the 500-900 nm range, and tones were measured using a commercial colorimeter. The experimental fitting proposed in this study could estimate the optical properties as a function of the skin tones through ITA values, by using an exponential function with a second-order polynomial exponent. This investigation aligns with prior studies involving human skin samples, and these findings hold promise for future clinical and diagnostic applications, particularly in the realm of light-based treatments to individual dermatological corrections in pigmented skin.

Histological effects of exposure to home hair removal laser radiation in kidney and liver of Swiss albino rats

Although laser irradiation is becoming a common practice in medicine and is now considered a preferred therapy for many challenging pain management issues, there is no clear understanding of its side effects on physiological and histological parameters. The current study aimed to determine the safety of home laser irradiation on liver and kidney tissues. Male Swiss albino rats were purchased from the Department of Biology at Thi-Qar University. The rats were randomly divided into two equivalent groups, each containing six rats: a control group that was left unexposed and a second group that was exposed to six pulses of radiation per day (with a pulse duration of 2-3 milliseconds) for two weeks. The results of the current study did not show any changes in the kidney and liver tissues of the group treated with the laser. We concluded that using a home laser has no effect on kidney and liver tissues.

Assessment of the influence of 660 and 808-nm PBM treatments on mitochondrial oxygen consumption of MG-63 osteoblast: a 3D cell culture study

This study explores the dose-dependent effects of 660-nm and 808-nm photobiomodulation (PBM) on mitochondrial oxygen respiration rate activity in MG-63 osteoblast cells using an innovative 3D in vitro spheroid model. MG-63 osteoblast cells were grown to 80% confluence and seeded in fish gelatin hydrogel (LunaGel™) to form 3D spheroids within 3-7 days. Spheroids were seeded on Seahorse microplates and incubated in a LunacrossLinker™ (visible light crosslinking system) for 2 min to give hydrogel a mid-stiffness of 3.5 kPa. Cells were exposed to PBM either 660-nm or 808-nm at panel setting of 5 J/cm2 and 15 J/cm2 and then assessed immediate (15 min before analysing) and 24 h time points. Mitochondrial activity was determined using an XFe96 Seahorse analyzer. Data distribution was assessed, and parametric or non-parametric tests and compared the mitochondrial respiratory capacity across different experimental conditions. The study indicated that 660-nm and 808-nm PBM could modulate mitochondrial functions in osteoblasts. The maximal respiratory rate for the fluency assessed at 808-nm wavelength was increased when cells were assessed immediate post. Interestingly, the 660-nm PBM-treated cells showed a decrease in oxygen consumption rate (OCR) at the basal and maximal bioenergetic state at all time points (immediate and 24 h.) and fluency compared to the untreated control. The effects of 660-nm and 808-nm wavelengths on osteoblast mitochondrial function suggest that PBM demonstrates differential modulation of osteoblast metabolism and bioenergetics depending on the wavelength. These findings have practical implications in both research and clinical settings, offering insights into selecting specific wavelengths for therapeutic applications.

Photobiomodulation on vocal training and rehabilitation: Delphi consensus based on experts

PURPOSE

To develop a consensus among speech-language pathologists who are voice specialists regarding the criteria for recommending and using photobiomodulation in the context of vocal therapy and training.

METHODS

Seven speech-language pathologists, experts in voice, and with experience in using photobiomodulation in vocal therapy and training participated. The Delphi technique was used to achieve consensus from a panel of experts accessed independently in two phases of collection. In Phase 1, the experts were contacted individually and participated in an interview with 12 questions to gather opinions on the use of photobiomodulation in the investigated context. The experts' responses were used to construct a questionnaire with 55 items presented as statements. The experts were asked to analyze each item and indicate their level of agreement on a five-point Likert scale. The content validity coefficient (CVC) was used to investigate the degree of agreement among the judges and to select the final items of the consensus.

RESULTS

Consensus was reached among the experts on 34 items investigated in this study, with a CVC ≥ 0.75. It was observed that 31 items achieved an excellent CVC (≥ 0.78), 14 items with a good CVC (0.60 ≥ CVC ≤ 0.77) and 10 items with a poor CVC (≤ 0.59). The total CVC was considered excellent, with a value of 0.78.

CONCLUSION

There was a consensus among experts about the use of photobiomodulation in vocal habilitation and rehabilitation. It has the potential to improve the criteria for prescribing and using this device by speech-language pathologists. The findings may be useful to improve the criteria for prescribing and the use of this device by speech-language pathologists, in addition to subsidizing the development of future research and clinical recommendations in the area.

The Use of a Proprietary Near-Infrared Laser to Enhance Wound Healing: A Preliminary Preclinical and Clinical Study

Background

Nonthermal light energy has been used to enhance wound healing. This is known as photobiomodulation. Although preclinical evidence is largely based on laser light, light-emitting diodes (LEDs) form the mainstay of clinical studies owing to the lack of available lasers for nonclinical use. However, it is speculated the 2 technologies exhibit dissimilar biological responses.

Objectives

The influence of a new, commercially available near-infrared laser device on the gene expression profile of human skin relative to an equivalent, near-infrared LED device was evaluated. Additionally, the wound healing potential of the device was examined in practice.

Methods

Defatted human skin was exposed to the laser (3), LED (3), or negative control (3) for 5 days. On Day 6, skin samples were biopsied for ribonucleic acid extraction and gene expression assays run for 107 genes of interest. Twenty patients with chronic wounds were randomized to receive standard wound care ± laser therapy 3 times weekly for 4 weeks, and wounds were analyzed for healing.

Results

The laser altered expression of 45 genes. Highly up-regulated genes (>5-fold change) included those implicated in wound healing and antiaging, whereas highly down-regulated genes included those implicated in inflammation and extracellular matrix integrity. The LED device altered expression of only 1 gene relative to negative controls. The laser reduced mean wound area by 78% and healed 4 of 10 wounds completely. In contrast, 8 of 10 of those receiving standard care exhibited no change.

Conclusions

A proprietary near-infrared laser exhibited superior ability to influence gene expression in healthy skin than an equivalent LED device and induced the healing of chronic wounds.

Level of Evidence 2 Therapeutic

Low-Level Laser and LED Therapy in Alopecia: A Systematic Review and Meta-Analysis

BACKGROUND

Low-level laser/LED therapy (LLLT) has been described as a treatment option for alopecia, but no study has comprehensively reviewed its efficacy in multiple alopecia types.

OBJECTIVE

To review and evaluate LLLT for various alopecia types.

MATERIALS AND METHODS

A systematic search of PubMed/MEDLINE, Embase, and CENTRAL was conducted to identify studies assessing the effect of LLLT on patients diagnosed with alopecia. Prespecified outcome measure was the change in hair density. Meta-analysis was performed to calculate the standardized mean difference in hair density before and after LLLT compared with placebo.

RESULTS

Thirty-eight studies were included that described 3,098 patients with androgenetic alopecia (2,930/3,098), scarring alopecia (49/3,098), alopecia areata (50/3,098), telogen effluvium (17/3,098), and chemotherapy-induced alopecia (32/3,098). The mean change in hair density increased significantly in androgenetic alopecia patients after LLLT for 4 to 26 weeks compared with placebo (<20 weeks: SMD = 1.14; 95% CI [0.51-1.78]; p = .000; I 2 = 88.26%; >20 weeks: SMD = 1.44; 95% CI [0.97-1.91]; p = .000; I 2 = 80.81%). Change in hair density was reported in 5 studies evaluating other alopecia types; however, statistical information was insufficient for meta-analysis.

CONCLUSION

LLLT is a promising treatment option for patients with androgenetic alopecia, but future studies are needed to better understand its efficacy in other alopecia types.

Periodontal response to nonsurgical accelerated orthodontic tooth movement

Tooth movement is a complex process involving the vascularization of the tissues, remodeling of the bone cells, and periodontal ligament fibroblasts under the hormonal and neuronal regulation mechanisms in response to mechanical force application. Therefore, it will inevitably impact periodontal tissues. Prolonged treatment can lead to adverse effects on teeth and periodontal tissues, prompting the development of various methods to reduce the length of orthodontic treatment. These methods are surgical or nonsurgical interventions applied simultaneously within the orthodontic treatment. The main target of nonsurgical approaches is modulating the response of the periodontal tissues to the orthodontic force. They stimulate osteoclasts and osteoclastic bone resorption in a controlled manner to facilitate tooth movement. Among various nonsurgical methods, the most promising clinical results have been achieved with photobiomodulation (PBM) therapy. Clinical data on electric/magnetic stimulation, pharmacologic administrations, and vibration forces indicate the need for further studies to improve their efficiency. This growing field will lead to a paradigm shift as we understand the biological response to these approaches and their adoption in clinical practice. This review will specifically focus on the impact of nonsurgical methods on periodontal tissues, providing a comprehensive understanding of this significant and understudied aspect of orthodontic care.

Effects of low-level laser irradiation on canine fibroblasts

Low-level laser (LLL) therapy is a well-known noninvasive treatment that stimulates fibroblasts to improve wound healing. LLL can improve fibroblast proliferation and migration without causing toxicity. The present study aimed to evaluate the effects of two laser wavelengths at different irradiation times on canine fibroblasts. Fibroblasts were isolated from canine oral mucosa. After seeding for 24 hr, the fibroblasts were irradiated using the Erchonia® EVL dual-diode laser at wavelengths of 405 nm (5 mW) and 640 nm (7.5 mW) with irradiation times of 120, 360, and 1,800 sec. The proliferating and viability cells were evaluated 24 hr after laser irradiation. Wound closure rates were calculated at 0, 24, and 48 hr after laser irradiation. Parameters, including proliferation cell, cell viability, and cell migration, tended to be higher in the 360-sec group (405 nm) and 120-sec group (640 nm) than in other groups. Our findings suggest that LLL therapy at wavelengths of 405 and 640 nm with an irradiation time of 120-360 sec (0.26-0.51 J/cm2) can stimulate the proliferation and migration of canine fibroblasts. This finding may contribute to a better understanding of the beneficial role of LLL stimulation in canine wound healing.

810-nm Photobiomodulation Evokes Glutamate Release in Normal and Rotenone-Dysfunctional Cortical Nerve Terminals by Modulating Mitochondrial Energy Metabolism

The dysfunction of mitochondria, the primary source of cellular energy and producer of reactive oxygen species (ROS), is associated with brain aging and neurodegenerative diseases. Scientific evidence indicates that light in the visible and near-infrared spectrum can modulate mitochondrial activity, a phenomenon known in medicine as photobiomodulation therapy (PBM-t). The beneficial effects of PBM-t on dementia and neurodegeneration have been reviewed in the literature. However, the molecular mechanisms underlying these findings have yet to be fully elucidated. This study investigates the mechanism behind dose-dependent glutamate release in nerve terminals after irradiation with 810 nm, 1 W for 60 s continuous, 1 cm2, 1 W/cm2, 60 J, 60 J/cm2 (810 nm-1 W) or 810 nm, 0.1 W for 60 s continuous, 1 cm2, 0.1 W/cm2, 6 J, 6 J/cm2 (810 nm-0.1 W), focusing on mitochondrial activities. The results show that PBM modulated the mitochondrial metabolism of cortical nerve terminals and supported a power-dependent increase in oxidative phosphorylation (OxPhos) activity when stimulated with pyruvate plus malate (P/M) or succinate (succ) as respiratory substrates. The PBM-induced increase in OxPhos was sensitive to adding rotenone (Complex I inhibitor) and antimycin A (Complex III inhibitor) when synaptosomes were stimulated with P/M, but only to antimycin A when stimulated with succ. This allowed us to observe that the glutamate efflux, disrupted in the presence of rotenone, was partially restored by PBM due to the increase in the OxPhos pathway led by Complex II. This evidence suggests that PBM, acting on mitochondria, could facilitate physiological communication within the neuron-astrocyte network through vesicular glutamate release, potentially regulating healthy brain function and brain dysfunction.

How long does the biological effect of a red light-emitting diode last on adipose-derived mesenchymal stem cells?

This research investigated the duration of the influence of red light-emitting diodes (LED, 630 nm; output power: 2452.5 mW; laser beam: 163.5 cm2; irradiance: 15 mW/cm2; radiant exposure: 4 J/cm2) on different periods after irradiation (6, 12, 24, 48, and 72 h) on adipose-derived mesenchymal stem cells' (AdMSCs) metabolism and paracrine factors. AdMSCs were irradiated three times every 48 h. Twenty-four hours after the last irradiation, there was a higher MTT absorbance, followed by a decrease after 48 h. The cells' secretome showed increased levels of IL-6 and VEGF after 12 and 24 h, but this was reversed after 48 h. Additionally, LED irradiation resulted in higher levels of nitrite and did not affect oxidative stress markers. LED irradiation had significant effects on AdMSCs after 24 h compared to other groups and its control group.

In vitro and in vivo evaluation of photo-induced antileishmanial activity of indocyanine green-loaded nanomicelles

Objectives

Due to its low toxicity and high absorbance in the range of 650 to 900 nm, indocyanine green (ICG) has garnered significant attention for its applications in photodynamic therapy (PDT) and photothermal therapy (PTT). However, its tendency to aggregate in aqueous environments limits its efficacy in both in vitro and in vivo applications. Encapsulating ICG in a biocompatible nanomicelle can improve its aqueous stability and photophysical properties. The present study investigated the synergistic effect of ICG-loaded nanomicelles upon irradiation by an 808-nm laser on Leishmania major (L. major) parasites.

Materials and Methods

Initially, a nanomicelle comprised ICG was synthesized and characterized. Then, the temperature increase during irradiation and promastigote viability were evaluated in vitro. Subsequently, the prepared samples' in vitro dark toxicity and phototoxicity were assessed via the MTS assay. Finally, the in vivo antileishmanial efficacy of the ICG-loaded nanomicelles formulation was investigated in BALB/c mice.

Results

The absorbance of ICG-loaded nanomicelles at 808 nm was more than 2 times greater than Free-ICG. Also, the prepared formulation exhibited a mean diameter of ~25 nm and a zeta potential of -2.3 ± 1 mV. The combination of ICG-loaded nanomicelles and 808 nm laser with a power density of 2.5 W cm-2 led to a significant reduction in the survival rate of promastigotes and lesion size of infected mice compared to control groups.

Conclusion

The PDT/PTT mediated by ICG-loaded nanomicelles can be considered a promising and efficient therapeutic method for L. major, as it is inexpensive, safe, and easy to implement.

Comparative Efficacy of Laser Versus Conventional Method in the Success of Circumferential Supracrestal Fiberotomy in Orthodontic Patients: A Systematic Review

Introduction: The relapse of rotated teeth is a significant concern in orthodontics, and circumferential supracrestal fiberotomy (CSF) presents a potential solution. Traditionally, CSF is performed using a surgical blade; however, employing a laser may reduce complications. This study aimed to systematically review the literature comparing laser-assisted CSF with conventional methods in orthodontic patients. Methods: A comprehensive search was conducted across the PubMed, Scopus, Web of Science, and Cochrane Library databases using a specific search strategy up to June 16, 2024. Data extraction was done in accordance with the defined inclusion and exclusion criteria. Results: Initially, a total of 293 articles were identified through the search process, and ultimately, four were selected for analysis based on specific inclusion and exclusion criteria. The studies involved various types of lasers including diode (810 to 940 nm), Er:YAG, and Er,Cr:YSGG lasers, and examined the effects of low-level laser therapy (LLLT) in conjunction with surgical interventions. Regarding relapse rates, two studies reported that both laser and surgical blade techniques demonstrated comparable efficacy, while adjunctive LLLT was effective in reducing relapse. In the other two studies, the use of laser therapy was found to be effective in decreasing relapse rates compared to the control group. Pain assessment results were inconclusive; one study reported reduced pain in the laser group, while another found no significant difference in pain levels between the laser and blade techniques. Furthermore, no significant differences were observed in periodontal pocket depth or gingival recession between the two methods. Conclusion: Within the limitations of the current systematic review, our findings indicate that there is no significant difference in relapse rates between laser and blade CSF procedures. Furthermore, our results suggest that the incorporation of photobiomodulation at higher doses is correlated with a reduction in relapse rates following fiberotomy procedures.

Dorsoventral photobiomodulation therapy safely reduces inflammation and sensorimotor deficits in a mouse model of multiple sclerosis

BACKGROUND

Non-invasive photobiomodulation therapy (PBMT), employing specific infrared light wavelengths to stimulate biological tissues, has recently gained attention for its application to treat neurological disorders. Here, we aimed to uncover the cellular targets of PBMT and assess its potential as a therapeutic intervention for multiple sclerosis (MS).

METHODS

We applied daily dorsoventral PBMT in an experimental autoimmune encephalomyelitis (EAE) mouse model, which recapitulates key features of MS, and revealed a strong positive impact of PBMT on the sensorimotor deficits. To understand the cellular mechanisms underlying these striking effects, we used state-of-the-art tools and methods ranging from two-photon longitudinal imaging of triple fluorescent reporter mice to histological investigations and patch-clamp electrophysiological recordings.

RESULTS

We found that PBMT induced anti-inflammatory and neuroprotective effects in the dorsal spinal cord. PBMT prevented peripheral immune cell infiltration, glial reactivity, as well as the EAE-induced hyperexcitability of spinal interneurons, both in dorsal and ventral areas, which likely underlies the behavioral effects of the treatment. Thus, aside from confirming the safety of PBMT in healthy mice, our preclinical investigation suggests that PBMT exerts a systemic and beneficial effect on the physiopathology of EAE, primarily resulting in the modulation of the inflammatory processes.

CONCLUSION

PBMT may therefore represent a new valuable therapeutic option to treat MS symptoms.

Synergistic Effects of Photobiomodulation and Differentiation Inducers on Osteogenic Differentiation of Adipose-Derived Stem Cells in Three-Dimensional Culture

Osteoporosis, a common metabolic bone disorder, leads to increased fracture risk and significant morbidity, particularly in postmenopausal women and the elderly. Traditional treatments often fail to fully restore bone health and may cause side effects, prompting the exploration of regenerative therapies. Adipose-derived stem cells (ADSCs) offer potential for osteoporosis treatment, but their natural inclination toward adipogenic rather than osteogenic differentiation poses a challenge. This study investigates a novel approach combining differentiation inducers (DIs), three-dimensional (3D) hydrogel scaffolds, and photobiomodulation (PBM) to promote osteogenic differentiation of immortalised ADSCs. A dextran-based 3D hydrogel matrix, supplemented with a DI cocktail of dexamethasone, β-glycerophosphate disodium, and ascorbic acid, was used to foster osteogenesis. PBM was applied using near-infrared (825 nm), green (525 nm), and combined wavelengths at fluences of 3 J/cm2, 5 J/cm2, and 7 J/cm2 to enhance osteogenic potential. Flow cytometry identified osteoblast-specific markers, while inverted light microscopy evaluated cellular morphology. Reactive oxygen species assays measured oxidative stress, and quantitative polymerase chain reaction (qPCR) revealed upregulated gene expression linked to osteogenesis. The findings demonstrate that integrating DIs, 3D hydrogels, and PBM effectively drives osteogenic differentiation in immortalised ADSCs. The PBM enhanced osteogenic marker expression, induced morphological changes, and upregulated gene activity, presenting a promising framework for bone regeneration. Future research should assess the stability and functionality of these differentiated cells and explore their applicability in preclinical models of bone injury or degeneration. This integrative approach demonstrated specific efficacy in promoting the osteogenic differentiation of ADSCs, highlighting its potential application in developing targeted treatments for osteoporosis.

Immediate effects of traditional and laser acupuncture in chronic non-specific neck pain: a randomized controlled clinical trial

Neck pain is considered one of the most prevalent global public health problems. This study aimed to compare the immediate and subsequent effects of traditional acupuncture (TA) and laser acupuncture (LA) therapies in individuals with chronic non-specific neck pain. Eighty-four individuals were randomly allocated into 3 groups: TA (needle acupuncture treatment), LA (laser acupuncture treatment: 808 nm; 100 mW; 10 J per point), and S-LA (sham laser acupuncture). The participants were men and women aged between 18 and 60 years who had experienced chronic non-specific neck pain for a minimum period of 3 months. The Tianzhu, Fengchi, Jianjing, and Jianzhongshu acupuncture points were stimulated bilaterally. The primary outcomes were pain intensities at rest and during active neck movements, assessed using the Numerical Rating Scale. The secondary outcomes were Pressure Pain Threshold, Temporal Summation of pain, Conditioned Pain Modulation, and Global Perceived Effect scale. The assessments were performed immediately before and after a single treatment session. Additionally, determinations of pain intensity at rest and Global Perceived Effect were performed in a follow-up assessment one month after the interventions. The results showed that the TA and LA interventions were equally significantly superior in reducing immediate pain compared to placebo laser acupuncture (p = 0.001). Traditional acupuncture and laser acupuncture provided equally effective reductions of pain intensity in patients with chronic non-specific neck pain. Clinical Trial registration: RBR-7vbw5gd (Brazilian Registry of Clinical Trials - ReBEC).

The Role of Photobiomodulation to Modulate Ion Channels in the Nervous System: A Systematic Review

Photobiomodulation (PBM) is a safe and effective neurotherapy that modulates cellular pathways by altering cell membrane potentials, leading to beneficial biological effects such as anti-inflammatory and neuroregenerative responses. This review compiles studies from PubMed up to March 2024, investigating the impact of light at wavelengths ranging from 620 to 1270 nm on ion channels. Out of 330 articles screened, 19 met the inclusion criteria. Research indicates that PBM can directly affect various ion channels by influencing neurotransmitter synthesis in neighboring cells, impacting receptors like glutamate and acetylcholine, as well as potassium, sodium channels, and transient receptor potential channels. The diversity of studies hampers a comprehensive meta-analysis for evaluating treatment strategies effectively. This systematic review aims to explore the potential role of optoelectronic signal transduction in PBM, studying the neurobiological mechanisms and therapeutic significance of PBM on ion channels. However, the lack of uniformity in current treatment methods underscores the necessity of establishing standardized and reliable therapeutic approaches.

Red wavelength-induced photobiomodulation enhances indocyanine green-based anticancer photodynamic therapy

Cancer is a global concern worldwide. Prostate cancer has high prevalence and mortality rates among men. Photodynamic therapy (PDT) is an alternative treatment that is promising and effective with fewer side-effects than conventional therapies. However, some factors may limit its efficacy. For this, PDT can be combined with other modalities such as photobiomodulation (PBM) which is commonly used for increased cell proliferation/differentiation and wound healing. In this study, PBM pre-treatment at 655 nm of wavelength with 1, 3, and 5 J/cm2 energy densities was applied to prostate cancer cells to investigate its role in indocyanine green (ICG)-mediated PDT applications. Following PBM treatment, various analyses were assessed including cell viability, cellular uptake of ICG, ATP production, nitric oxide release, reactive oxygen species generation, and the changes in mitochondrial membrane potential. Increased cell death was observed with the PBM pre-treatment at 1 and 3 J/cm2 energy densities depending on ICG incubation time. Intracellular ROS generation and nitric oxide release by PBM had a significant impact on anticancer PDT action. An enhanced anticancer PDT effect was obtained with the PBM pre-treatment which may become a valuable modality to increase the sensitivity of the cancerous cells to PDT applications.

Photobiomodulation CME part I: Overview and mechanism of action

Photobiomodulation (PBM), previously known as low-level laser light therapy, represents a noninvasive form of phototherapy that utilizes wavelengths in the red light (RL, 620-700 nm) portion of the visible light (VL, 400-700 nm) spectrum and the near-infrared (NIR, 700-1440 nm) spectrum. PBM is a promising and increasingly used therapy for the treatment of various dermatologic and nondermatologic conditions. Photons from RL and NIR are absorbed by endogenous photoreceptors including mitochondrial cytochrome C oxidase (COX). Activation of COX leads to the following changes: modulation of mitochondrial adenosine triphosphate (ATP), generation of reactive oxygen species (ROS), and alterations in intracellular calcium levels. The associated modulation of ATP, ROS and calcium levels promotes the activation of various signaling pathways (eg, insulin-like growth factors, phosphoinositide 3-kinase pathways), which contribute to downstream effects on cellular proliferation, migration, and differentiation. Effective PBM therapy is dependent on treatment parameters (eg, fluence, treatment duration and output power). PBM is generally well-tolerated and safe with erythema being the most common and self-limiting adverse cutaneous effect.

CD8+ T-cell exhaustion: Impediment to triple-negative breast cancer (TNBC) immunotherapy

CD8+ T-cell exhaustion has been identified as a significant contributor to immunosuppression and immune escape in triple-negative breast cancer (TNBC). Dysfunction due to cell exhaustion is characterized by reduced effector capacity and sustained expression of inhibitory receptors (IRs). The factors contributing to CD8+ T-cell exhaustion are multifaceted, encompassing external influences such as the upregulation of IRs, reduction of effector cytokines, and internal changes within the immune cell, including transcriptomic alterations, epigenetic landscape remodeling, and metabolomic shifts. The impact of the altered TNBC tumor microenvironment (TME) on Tex is also a critical consideration. The production of exhausted CD8+ T-cells (CD8+ Tex) is positively correlated with poor prognosis and reduced response rates to immunotherapy in TNBC patients, underscoring the urgent need for the development of novel TNBC immunotherapeutic strategies that target the mechanisms of CD8+ T-cell exhaustion. This review delineates the dynamic trajectory of CD8+ T-cell exhaustion development in TNBC, provides an update on the latest research advancements in understanding its pathogenesis, and offers insights into potential immunotherapeutic strategies.

Monocarbonyl curcuminoids as potential photosensitizers in photodynamic therapy against skin cancer

Two monocarbonyl dimethylamino curcuminoids, one derived from acetone (C3) and the second one from cyclohexane (C6), were synthesized aiming to study their photophysical properties and anticancer photodynamic potential. Compound C6 exhibited lower absorbance and fluorescence than C3. Photobleaching studies showed that C3 and C6 photostability behavior in DMSO differ significantly. C3 was completely photoconverted into a new species absorbing at lower wavelength than the parent compound, whereas, C6, upon a 30 min irradiation at λ = 440 nm with 15 mW/cm2 reached a photostationary phase where a smaller amount of the initial compound coexists with some photoproducts of higher and lower absorbance. Both compounds were able to generate significant amounts of ROS upon irradiation in an aqueous environment and exhibited successful intracellular localization in skin cancer cells (A431 cells). After dark cytotoxicity studies the concentrations of 5 μM and 1 μM for C3 and C6, respectively, were selected for the PDT assessment. C3 presented light dose-dependent photodynamic activity against A431 cells, resulting in 40 % cell viability after 12 min of light irradiation (440 nm, 15 mW/cm2). On the other side, C6 showed a biphasic light dose PDT effect with cell viability gradually decreasing up to 50 % after 5 min of light exposure, and then increasing again after 8 and 12 min of light exposure. The photodynamic performance of C6 may provide a new insight into the development of PSs with reduced prolonged photosensitivity.

Implantable and transcutaneous photobiomodulation promote neuroregeneration and recovery of lost function after spinal cord injury

Spinal cord injury (SCI) is a cause of profound and irreversible damage, with no effective therapy to promote functional recovery. Photobiomodulation (PBM) may provide a viable therapeutic approach using red or near-infrared light to promote recovery after SCI by mitigating neuroinflammation and preventing neuronal apoptosis. Our current study aimed to optimize PBM dose regimens and develop and validate the efficacy of an invasive PBM delivery paradigm for SCI. Dose optimization studies were performed using a serum withdrawal model of injury in cultures of primary adult rat dorsal root ganglion neurons (DRGN). Implantable and transcutaneous PBM delivery protocols were developed and validated using cadaveric modeling. The efficacy of PBM in promoting recovery after SCI in vivo was studied in a dorsal column crush injury model of SCI in adult rats. Optimal neuroprotection in vitro was achieved between 4 and 22 mW/cm2. 11 mW/cm2 for 1 min per day (0.66 J/cm2) increased cell viability by 45% over 5 days (p <0.0001), increasing neurite outgrowth by 25% (p <0.01). A method for invasive application of PBM was developed using a diffusion-tipped optogenetics fiber optic. Delivery methods for PBM were developed and validated for both invasive (iPBM) and noninvasive (transcutaneous) (tcPBM) application. iPBM and tcPBM (24 mW/cm2 at spinal cord, 1 min per day (1.44 J/cm2) up to 7 days) increased activation of regeneration-associated protein at 3 days after SCI, increasing GAP43+ axons in DRGN from 18.0% (control) to 41.4% ± 10.5 (iPBM) and 45.8% ± 3.4 (tcPBM) (p <0.05). This corresponded to significant improvements at 6 weeks post-injury in functional locomotor and sensory function recovery (p <0.01), axonal regeneration (p <0.01), and reduced lesion size (p <0.01). Our results demonstrated that PBM achieved a significant therapeutic benefit after SCI, either using iPBM or tcPBM application and can potentially be developed for clinical use in SCI patients.

Prevention and reversal of neuropathic pain by near-infrared photobiomodulation therapy in male and female rats

Pathological nociception arising from peripheral nerve injury impacts quality of life. Current therapeutics are generally ineffective. However, photobiomodulation therapy (PBMT) has shown promise in addressing this issue. We aimed to assess the potential anti-allodynic effects of 2 p.m. protocols, each applied transcutaneously over the peripheral nerve injury. In addition to evaluating nociceptive behavior, we also conducted morphological analysis using electron microscopy (EM) to investigate potential ultrastructural changes at the cellular level. We sought to determine, using the chronic constriction injury (CCI) model, whether our parameters could alleviate established allodynia and/or dampen allodynia development. Adult male and female rats with CCI or sham were treated with PBMT (850-nm wavelength) for 2 min, 3 times a week over three or four weeks across three studies, where PBMT began either before or after CCI. Allodynia was assessed prior to surgery and across weeks and, at the conclusion of the third study, sciatic nerve was processed for EM and histomorphometrically evaluated. The results showed that PBMT before versus after CCI injury yielded similar behaviors, effectively decreasing allodynia. Interestingly, these positive effects of PBMT do not appear to be accounted by protection of the sciatic injury site, based on EM. CCI reliably decreased axon size and the number of myelinated axons present in both PBMT and control groups. While PBMT reduced the number of C-fibers in CCI samples, no improvement in any measure was observed in response to PBMT.

A wearable and stretchable dual-wavelength LED device for home care of chronic infected wounds

Phototherapy can offer a safe and non-invasive solution against infections, while promoting wound healing. Conventional phototherapeutic devices are bulky and limited to hospital use. To overcome these challenges, we developed a wearable, flexible red and blue LED (r&bLED) patch controlled by a mobile-connected system, enabling safe self-application at home. The patch exhibits excellent skin compatibility, flexibility, and comfort, with high safety under system supervision. Additionally, we synthesized a sprayable fibrin gel (F-gel) containing blue light-sensitive thymoquinone and red light-synergistic NADH. Combined with bLED, thymoquinone eradicated microbes and biofilms within minutes, regardless of antibiotic resistance. Furthermore, NADH and rLED synergistically improved macrophage and endothelial cell mitochondrial function, promoting wound healing, reducing inflammation, and enhancing angiogenesis, as validated in infected diabetic wounds in mice and minipigs. This innovative technology holds great promise for revolutionizing at-home phototherapy for chronic infected wounds.

The effects of fulvic acids and low-level laser therapy on orthodontic retention in rats

BACKGROUND

Shortening retention time and minimizing relapse rates are ongoing challenges in orthodontics. This study investigated the effects of natural fulvic acids (FAs) and low-level laser therapy (LLLT) on orthodontic retention in rats.

METHODS

Seventy-two male Sprague-Dawley rats underwent mesial movement of the left maxillary first molar using a 50 g force via a nickel-titanium tension spring. After three weeks of movement, the rats entered the retention phase with retainer wires and were divided into four groups: Control (no intervention), FAs (80 mg/kg orally daily), LLLT (808 nm laser twice weekly), and FAs + LLLT (both treatments). Retainers were removed on days 7, 14, and 21 for a 3-day relapse assessment. Maxillary impressions were analyzed for relapse rates using 3Shape software, alongside histological and immunohistochemical evaluations of bone morphogenetic protein-2 (BMP-2) expression in periodontal tissues, with differences among groups analyzed using an ordinary two-way analysis of variance (ANOVA).

RESULTS

The relapse rate decreased over time, particularly at 10, 17, and 24 days (p < 0.001). The FAs group did not significantly affect relapse rates compared to the control group (p = 0.084). In contrast, both the LLLT and FAs + LLLT groups significantly reduced relapse rate (p < 0.001), with no significant difference between these groups (p = 0.555). Histological examination revealed active osteoclasts on day 10, decreasing by days 17 and 24. The LLLT and FAs + LLLT groups showed less local cementum resorption and better periodontal fiber arrangement. All treatment groups significantly increased BMP-2 expression (P < 0.05) compared to controls. with LLLT and FAs + LLLT differing significantly from FAs (P < 0.001), though no difference was observed between LLLT and FAs + LLLT (P = 0.578).

CONCLUSIONS

FAs did not significantly reduce relapse rate with retainers, while LLLT effectively reduced relapse rates, showing no additional benefit from combining FAs with LLLT. Both FAs and LLLT increased BMP-2 expression in PDL fibroblasts but with no synergistic effect.

A pilot study on the potential of photobiomodulation to safely modify symptoms of an overactive bladder

Background

Photobiomodulation (PBM) may stabilize autonomic neural drive from the pontine micturition Center to the urinary bladder in individuals with overactive bladder (OAB) symptoms.

Methods

A safety profile study preceded a single-case experimental design with repeated measures across subjects to establish the safety and effect direction of PBM to modify symptoms in patients with OAB.

Results

No adverse events occurred with PBM, specifically blood pressure remained unchanged. Urinary frequency improved significantly during the intervention and at follow-up. PBM therapy was associated with a meaningful impact on OAB-related quality of life and a small to medium-to-high effect size on OAB symptom severity.

Conclusion

Nasal application of PBM is safe and may impact OAB symptoms. A controlled trial of PBM in patients with lower urinary tract symptoms is warranted.

Effectiveness of the Association of Fibrin Scaffolds, Nanohydroxyapatite, and Photobiomodulation with Simultaneous Low-Level Red and Infrared Lasers in Bone Repair

Biomaterials and biopharmaceuticals for correcting large bone defects are a potential area of translational science. A new bioproduct, purified from snake venom and fibrinogen from buffalo blood, aroused interest in the repair of venous ulcers. Expanding potential uses, it has also been used to form biocomplexes in combination with bone grafts, associated with physical therapies or used alone. The aim of this preclinical study was to evaluate low-level laser photobiomodulation (PBM) in critical defects in the calvaria of rats filled with nanohydroxyapatite (NH) associated with the heterologous fibrin biopolymer (HFB). Sixty animals were used, divided into six groups (n = 10 each): G1 (NH); G2 (HFB); G3 (NH + HFB); G4 (NH + PBM); G5 (HFB + PBM); G6 (NH + HFB + PBM). PBM simultaneously used red (R) and infrared (IR) light emission, applied intraoperatively and twice a week, until the end of the experiment at 42 days. Microtomography, bone formation can be seen initially at the margins of the defect, more evident in G5. Microscopically, bone formation demonstrated immature and disorganized trabeculation at 14 days, with remnants of grafting materials. At 42 days, the percentage of new bone formed was higher in all groups, especially in G5 (HFB, 45.4 ± 3.82), with collagen fibers at a higher degree of maturation and yellowish-green color in the birefringence analysis with Picrosirius-red. Therefore, it is concluded that the HFB + PBM combination showed greater effectiveness in the repair process and presents potential for future clinical studies.

Tailoring photobiomodulation to enhance tissue regeneration

Photobiomodulation (PBM), the use of biocompatible tissue-penetrating light to interact with intracellular chromophores to modulate the fates of cells and tissues, has emerged as a promising non-invasive approach to enhancing tissue regeneration. Unlike photodynamic or photothermal therapies that require the use of photothermal agents or photosensitizers, PBM treatment does not need external agents. With its non-harmful nature, PBM has demonstrated efficacy in enhancing molecular secretions and cellular functions relevant to tissue regeneration. The utilization of low-level light from various sources in PBM targets cytochrome c oxidase, leading to increased synthesis of adenosine triphosphate, induction of growth factor secretion, activation of signaling pathways, and promotion of direct or indirect gene expression. When integrated with stem cell populations, bioactive molecules or nanoparticles, or biomaterial scaffolds, PBM proves effective in significantly improving tissue regeneration. This review consolidates findings from in vitro, in vivo, and human clinical outcomes of both PBM alone and PBM-combined therapies in tissue regeneration applications. It encompasses the background of PBM invention, optimization of PBM parameters (such as wavelength, irradiation, and exposure time), and understanding of the mechanisms for PBM to enhance tissue regeneration. The comprehensive exploration concludes with insights into future directions and perspectives for the tissue regeneration applications of PBM.

Photobiomodulation use in ophthalmology - an overview of translational research from bench to bedside

Photobiomodulation (PBM) refers to the process in which wavelengths of light are absorbed by intracellular photoacceptors, resulting in the activation of signaling pathways that culminate in biological changes within the cell. PBM is the result of low-intensity light-induced reactions in the cell in contrast to thermal photoablation produced by high-intensity lasers. PBM has been effectively used in the clinic to enhance wound healing and mitigate pain and inflammation in musculoskeletal conditions, sports injury, and dental applications for many decades. In the past 20 years, experimental evidence has shown the benefit of PBM in increasing numbers of retinal and ophthalmic conditions. More recently, preclinical findings in ocular models have been translated to the clinic with promising results. This review discusses the preclinical and clinical evidence of the effects of PBM in ophthalmology and provides recommendations of the clinical use of PBM in the management of ocular conditions.

LLLT accelerates experimental wound healing under microgravity conditions via PI3K/AKT-CCR2 signal axis

Background and Purpose

The risk of skin injuries in space is increasing with longer space missions and a growing astronaut population. This highlights the importance of understanding the adverse effects of weightlessness on wound healing. The objective of this research was to examine the therapeutic potential of Low-Level Light Therapy (LLLT) on skin healing processes under simulated microgravity (SMG) conditions and uncover the underlying molecular mechanisms, thus providing innovative solutions and a sound theoretical basis for space skin injuries.

Methods

Hindlimb unloading (HU) mice models were used to simulate weightlessness conditions, with or without a complete management of LLLT for 14 days. A systematic testing consisting of HE, Masson and immunohistochemical staining was performed against the standardized mouse tissue specimens. In vitro assessment of cellular biological functions under SMG conditions was carried out in the rotation system of culture (RSOC) using HaCaT and NIH3T3 cell-lines.

Results

Under SMG conditions, LLLT significantly reduced skin wound area in HU mice, especially on Days 10 (p < 0.001), accompanied by increased collagen deposition and elevated levels of Ki67 and CD31. Moreover, LLLT showed impressive anti-inflammatory effects represented by the reduced in pro-inflammatory markers including LY6G, F4/80 and CD86, as well as the decreased levels of IL-1β, IL-6 and TNF-α. Conversely, an elevation in the anti-inflammatory marker CD206 was observed. By employing bioinformatics technology, we further found the PI3K/AKT signaling was prominent in the KEGG pathway analysis and CCR2 acted as a hub gene in the interaction network. Therefore, we demonstrated that LLLT could enhance the phosphorylation of PI3K/AKT and reduce CCR2 expression under SMG conditions, while CCR2 knockdown promoted the phosphorylation of PI3K/AKT, suggesting an important role of CCR2/PI3K/AKT signal axis in LLLT-accelerated wound healing under SMG conditions.

Conclusion

LLLT induced activation of the PI3K/AKT signaling pathway through suppression of CCR2 expression, which significantly enhanced skin wound healing under SMG conditions.s.

Effectiveness of Photobiomodulation in Reducing Pain and Disability in Patients With Knee Osteoarthritis: A Systematic Review With Meta-Analysis

OBJECTIVE

Photobiomodulation (PBM) is not implemented in routine clinical management for knee osteoarthritis. This study aims to systematically investigate the effects of PBM in patients with knee osteoarthritis, comparing with placebo to understand its true clinical effects.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane databases were searched up to October 2023. Randomized placebo-controlled trials applying PBM versus placebo were included. Study characteristics, intervention parameters, and patient-reported and physical examination outcome measures were collected. The risk of bias was judged using the Cochrane risk-of-bias tool for randomized trials (version 2) and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) to interpret the certainty of results.

RESULTS

Ten studies were included comprising 542 participants. All studies were judged with unclear to a high risk of bias. Meta-analysis for pain at rest (6 studies) showed that PBM significantly reduced pain at rest as compared to placebo (-0.7 [95% CI = -1.1 to -0.2]), moderate effect, very low certainty of evidence, whereas for the Timed "Up & Go" Test (three studies), no significant effect was detected. Statistically significantly within-group (PBM) mean improvement was detected for pain, Lequesne Index, and gait performance outcomes, but not always clinically relevant or significant when compared to placebo.

CONCLUSION

PBM reduces pain intensity in patients with knee osteoarthritis and may improve disability. However, the very low certainty of evidence does not allow to recommend its isolated use but may be used to complement other widely recommended therapies. More rigorous clinical trials and the revision of the recommended dosage guidelines are warranted to increase the strength of evidence.

IMPACT

The findings indicate that photobiomodulation can reduce pain and improve disability in patients with knee osteoarthritis. However, researchers should continue to investigate isolated photobiomodulation intervention versus placebo and extend the dosage guidelines to other types of light emitters.

Effect of 460 nm blue light PBM on human MeWo melanoma cells

Photobiomodulation (PBM) using 460 nm blue light has been shown to have an inhibitory effect on skin cancer cells. In this study, we used a continuous LED light source with a wavelength of 460 nm and designed various combinations of power density (ranging from 6.4 to 25.6 mW) and dose (ranging from 0.96 to 30.72 J/cm2) to conduct treatment experiments on MeWo cells to investigate the effects of blue light on MeWo melanoma cells. We are focusing on cell viability, cytotoxicity, mitochondrial function, oxidative stress, and apoptosis. We found that blue light inhibits these melanoma cells through oxidative stress and DNA damage, and this inhibition intensifies at higher irradiance levels. Although the cells initially attempt to resist the stress induced by the treatment, they eventually undergo apoptosis over time. These findings contribute to understanding melanoma's molecular response to blue light PBM, lay the groundwork for future clinical applications.

Effect of photobiomodulation on lower urinary tract dysfunction in rat cystitis model

OBJECTIVE

Photobiomodulation selectively controls the activity of the sensory nervous system associated with A-delta and C fibers. Hypersensitivity involving the afferent A-delta and C fibers occurs in cystitis and decreases urinary function. This study aimed to investigate the effect of photobiomodulation on urinary storage dysfunction and voiding functions in cystitis model rats.

METHODS

We prepared the rat cystitis model. Under anesthesia, a cannula was connected to the bladder via a ventral incision. 0.3% acetic acid or saline was injected into the bladder. Continuous cystometry was performed, measuring bladder pressure and voiding urine volume with rats freely mobile. Laser irradiation was applied to the L6 lumbosacral intervertebral foramen using an 830 nm laser. Residual urine was extracted post-cystometry.

RESULTS

In the rat cystitis model groups, there was a significant decrease in the voiding interval and volume compared to the group receiving normal saline infusion. After sham or laser irradiation, only the group with laser irradiation showed a significant increase in voiding interval (217%, p = 0.0002) and voiding volume (192%, p = 0.0012) in the parameters of storage dysfunction. The basal pressure, intravesical pressure, and residual urine volume remained unchanged in all groups before and after irradiation.

CONCLUSIONS

This study indicates that photobiomodulation may improve urine storage dysfunction without exacerbating voiding function in a rat model of cystitis. Thus, photobiomodulation may be a new treatment option for the hypersensitivity and detrusor overactivity caused by cystitis.

Biomimetic Ghost Nanomedicine-Based Optotheranostics for Cancer

Theranostic medicine combines diagnostics and therapeutics, focusing on solid tumors at minimal doses. Optically activated photosensitizers are significant examples owing to their photophysical and chemical properties. Several optotheranostics have been tested that convert light to imaging signals, therapeutic radicals, and heat. Upon light exposure, conjugated photosensitizers kill tumor cells by producing reactive oxygen species and heat or by releasing cancer antigens. Despite clinical trials, these molecularly conjugated photosensitizers require protection from their surroundings and a localized direction for site-specific delivery during blood circulation. Therefore, cell membrane biomimetic ghosts have been proposed for precise and safe delivery of these optically active large molecules, which are clinically relevant because of their biocompatibility, long circulation time, bypass of immune cell recognition, and targeting ability. This review focuses on the role of biomimetic nanoparticles in the treatment and diagnosis of tumors through light-mediated diagnostics and therapy, providing insights into their preclinical and clinical status.

Therapeutic Photobiomodulation Before Strenuous Exercise Attenuates Shoulder Muscle Fatigue

CONTEXT

Photobiomodulation therapy (PBMT) applied as a preconditioning treatment before exercise has been shown to attenuate fatigue and improve skeletal muscle contractile function during high-intensity resistance exercise. Practical implications for preconditioning muscles with PBMT before fatiguing exercise include a safe and noninvasive means to enhance performance and reduce the risk of musculoskeletal injury.

OBJECTIVE

To examine the muscle fatigue-attenuating effects of PBMT on performance of the shoulder external-rotator muscle group when applied as a preconditioning treatment before high-intensity, high-volume resistance exercise.

DESIGN

Sham-controlled, crossover design.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty healthy men (n = 8) and women (n = 12) between the ages of 18 and 30 years.

INTERVENTION(S)

Photobiomodulation therapy was administered using a near-infrared laser (λ = 810/980 N·m, 1.8 W/cm2, treatment area = 80-120 cm2) to the shoulder external-rotator muscles at a radiant exposure of 10 J/cm2. Participants performed 12 sets of isokinetic shoulder exercise. Each set consisted of 21 concentric contractions of internal and external rotation at 60°/s. The sets were subdivided into 3 blocks of exercise (block 1: sets 1-4; block 2: sets 5-8; block 3: sets 9-12).

MAIN OUTCOME MEASURE(S)

Normalized peak torque (N·m/kg), average peak torque (N·m), total work (N·m), and average power (W).

RESULTS

During the last block of exercise (sets 9-12), all performance measures for the active PBMT condition were 6.2% to 10% greater than the sham PBMT values (P < .02 to P < .001).

CONCLUSIONS

Photobiomodulation therapy attenuated fatigue and improved muscular performance of the shoulder external rotators in the latter stages of strenuous resistance exercise.

Efficacy of Photobiomodulation Therapy in Older Adults: A Systematic Review

BACKGROUND

The aim was to determine whether there is any available evidence on the efficacy of photobiomodulation therapy (PBMT) in older adults.

METHODS

A literature search was performed including all articles published up to February 2024. Studies reporting data on PBMT in older adults were included. This study was registered with PROSPERO.

RESULTS

In total, 406 studies were identified. After eliminating duplicates and irrelevant studies, 10 records were included in the final review. In all included studies, the protocols used to deliver PBMT were different in terms of type of device, wavelength, irradiation duration, and pulse frequency. In neurodegenerative diseases, two studies reported non-significant results, while two studies reported efficacy of PBMT. In wounds and ulcers, two out of three studies reported efficacy of PBMT. In macular degeneration, one study reported efficacy of PBMT. One study on hyposalivation reported efficacy of PBMT.

CONCLUSION

PBMT appears to be a promising complementary treatment. All studies reported good compliance and safety throughout the treatment. In the future, it will be essential to harmonize PBMT parameters. Further studies are warranted to define the best indications, the most effective protocols, and the right population to target for use in routine practice.

Photobiomodulation versus fractional carbon dioxide laser for stria alba in phototype III-IV: a randomized controlled study

Striae distensae are common dermatological complaint. Cold laser using low-level light/laser therapy (LLLT) offers healing and analgesic effects and was not yet compared to 'hot lasers' efficacy. Study objective: to assess the efficacy and safety of LLLT in the management of stria alba compared to fractional carbon dioxide (FCO2) laser alone and to the combined use of both devices. Thirty patients with stria alba were randomized to receive either LLLT using diode 808 nm; 8-12 sessions, 2-3 sessions weekly (Group A) or FCO2 laser; 2 monthly sessions (Group B) or combined both devices simultaneously (Group C). Follow up was at 1 month and 3 months after last session. The efficacy of LLLT was statistically comparable to FCO2, despite numerical superiority of the latter. The combined group had the least numerical values in all efficacy outcomes. Patients in LLLT group did not experience any downtime. LLLT is effective in the management of stria alba comparable to the FCO2 laser. The lack of downtime with LLLT is reflected positively on patient's satisfaction. However, this is counterbalanced by the frequent weekly visits. Although adding LLLT to FCO2 laser palliates the laser side effects but it offers the least efficacy. Trial registration number NCT04165226 (clinicaltrials.gov).

Higher percentage of CD34+ stem cells and elevated efficacy in androgenetic alopecia treatment observed in CGF prepared from 640 nm laser-pretreated blood: A preliminary study

BACKGROUND

Concentrated growth factor (CGF) injection has proven effective in treating androgenetic alopecia (AGA). The primary mechanism of CGF in treating AGA is thought to be the CD34+ stem cells and platelets-associated growth factors being injected into the scalp. CGF efficacy in treating AGA may rely on the activation level of these stem cells and platelets. The 640 nm laser is a United States Food and Drug Administration approved AGA treatment that activates follicle stem cells. Therefore, we hypothesize that pretreating CGF with a 640 nm laser may further activate CD34+ stem cells and platelets, thereby improving the efficacy of CGF in treating AGA.

OBJECTIVE

This study aims to investigate whether 640 nm laser pretreated CGF (640CGF) has a greater effect in treating AGA than 640 nm laser non-pretreated CGF (N640CGF) and evaluate whether 640 nm laser pretreatment changed CD34+ cell percentage.

METHODS

This study enrolled 10 patients (8 male, 2 female) with AGA aged 18-60 years who received CGF injections. The 640CGF group was pretreated with a 640 nm laser at an energy density of 4 J/cm2, with a 30 cm irradiation distance for 30 min. Half of the scalp was treated with 640CGF, whereas the other half was treated with N640CGF. The injection was prepared by a doctor who did not know which blood tube had been pretreated. The treatment efficacy was evaluated using a trichoscope 1 month after injection.

RESULTS

All 10 (100%) patients participated in the follow-up visit, and a higher quantity of new hairs was observed on the side injected with 640CGF than N640CGF (p = 0.019). Additionally, fewer malnourished hairs were observed on the 640CGF pretreated side (p = 0.015). No serious adverse events were reported.

CONCLUSIONS

A higher percentage of CD34+ stem cells and improved efficacy in AGA treatment could be observed with CGF prepared from 640 nm laser-pretreated blood.

Effects of photobiomodulation therapy on muscle function in individuals with multiple sclerosis

BACKGROUND

In people with multiple sclerosis (pwMS), muscle fatigue and weakness are common issues that can interfere with daily activities. Photobiomodulation therapy (PBMT), comprising light in a 600-1100 nm bandwidth, is a low-level laser therapy thought to improve muscle performance in non-disease populations, in part, by improving mitochondrial function and thus, might be beneficial in pwMS. Given this potential, we aimed to investigate the effects of PBMT on muscle performance in pwMS, both in the short-term and over an extended period.

METHODS

This study consisted of two parts with a randomized double-blind crossover design. In study I, muscle function was assessed in four sessions before and after PBMT in ambulatory pwMS (N = 17, F = 14) as follows: maximal voluntary contraction (MVC) and muscle fatigue of the right tibialis anterior (TA) muscle was compared at baseline and following a two-min submaximal fatiguing contraction. Then, PBMT was administered to the belly of TA muscle at different doses of energy of an active device (40 J, 80 J, 120 J) or placebo. The muscle function assessment was then repeated.

OUTCOME VARIABLES

muscle force recovery (%), muscle fatigue (%). Statistical tests included McNemar's exact test, Wilcoxon signed-rank test, and the Friedman test. In study II, a subgroup from study I (N = 12, F = 11) received individualized doses (i.e., best dose-effect observed in study I) of active, or placebo PBMT, which was administered on the TA muscle for two weeks. Muscle function assessments were performed pre- and post-PBMT in four sessions similar to study I.

OUTCOME VARIABLES

Baseline strength (N), endurance time (s), and muscle fatigue (%). The Wilcoxon signed-rank test was used for statistical analysis. Values are reported as mean (SD).

RESULTS

In study I, participants who received a high dose of PBMT showed significant improvement in force recovery (101.89 % (13.55 %)) compared to the placebo group (96.3 % (18.48 %); p = 0.03). Muscle fatigue did not significantly improve with either active PBMT or placebo. In study II, active PBMT resulted in a significant improvement in muscle strength compared to both the baseline (pre-PBMT = 162.70 N (37.52 N); post-PBMT = 185.56 N (33.95 N); p = 0.01) and the placebo group (active PBMT: mean-change = 22.87 N (23.67 N); placebo: mean-change = -4.12 N (31.95 N); p = 0.02). Endurance time and muscle fatigue did not show significant improvement with either active PBMT or placebo.

CONCLUSION

Our findings suggest that an individualized dose of PBMT might improve muscle performance, including force recovery and strength in individuals with mild-moderate MS. Therefore, PBMT might be a novel therapeutic modality, either as a standalone treatment or in combination with other interventions, to improve muscle performance in pwMS.

Beneficial changes in gut microbiota after phototherapy for neonatal hyperbilirubinemia

Phototherapy is the most commonly used treatment for neonatal hyperbilirubinemia (NH). Gut microbiota is involved in bilirubin metabolism; however, it is uncertain whether this is affected by phototherapy. The present study included 43 newborns with hyperbilirubinemia and collected fecal samples for high-throughput sequencing before and after phototherapy. Selection α diversity analysis was used to determine the differences in diversity and abundance between the two groups, whereas similarity was determined using β diversity analysis. Linear discriminant analysis effect size analysis was used to screen for markedly different bacteria. The structure of the gut microbiota in newborns with hyperbilirubinemia changed after phototherapy, with a significant decrease in abundance and diversity. The changes in the key bacterial species were characterized by an increase in the abundance of Streptococcus salivarius and a decrease in the abundance of Escherichia, Klebsiella pneumoniae, Rothia mucilaginosa and Streptococcus oralis. These changes mainly manifested as an increase in beneficial bacteria and a decrease in opportunistic bacteria, which may not be related to the side effects of phototherapy. These results can provide theoretical assistance for microbiological research on the later stages of NH.

Immediate effects of photobiomodulation on saliva production

PURPOSE

To verify the immediate effects of photobiomodulation on the production of salivary flow and the correlation of demographic, anthropometric and medication use data.

METHODS

The study included 100 healthy individuals, aged between 18 and 76 years (mean 27.2 years), randomly split into an experimental group and a placebo group. Assessments of anthropometric measurements, self-perception of saliva production and sialometry were performed. Next, LASER irradiation was carried out at an infrared wavelength (808 nanometers) with 100 milliwatts (mw) of power at five intraoral points: on the sublingual glands and bilaterally on the submandibular and parotid glands, at doses of 9, 18 and 24 joules (J). Sialometry was repeated after each application. The control group received the same procedures with placebo equipment.

RESULTS

There was a statistical association in the self-perception of reduced saliva in the experimental group for the 24J dose and in sialometry and in the reduction in salivary flow for the 18J and 24J doses and an increase to 9J, in both groups. There was no association when comparing the experimental and placebo groups. Multiple multinomial regression analysis revealed that the reduction or increase in salivary flow is independent of demographic, anthropometric and medication use variables.

CONCLUSION

The bioinhibitory action of photobiomodulation on healthy salivary glands occurred at a dose of 18J and 24J, while the biostimulant action happened at a dose of 9J, regardless of demographic, anthropometric variables and medication use. The self-perception of reduced salivary flow occurred at 24J.