Photobiomodulation: A review of the molecular evidence for low level light therapy

Effects of photobiomodulation therapy (660-nm laser) on median nerve function in Wistar rats

This study investigates the effects of photobiomodulation (PBM) with a 660-nm laser on nerve regeneration and muscle morphometry following median nerve axonotmesis in rats. Sixteen Wistar rats were divided into a control group and laser-treated group, with the latter receiving 10 applications of PBM (660 nm; 20 mW; 10 J/cm2; 0.4 J; and 20 s) over 2 weeks. Functional analysis was performed using the grasping test, which measures the grip strength of the forelimb digits to evaluate motor function of the median nerve. Morphometric analyses were conducted on the median nerve, flexor digitorum (FD) muscle, and flexor carpi radialis (FCR) muscle. PBM led to functional improvement, with significant differences observed on the 21st day post-injury. However, no significant differences between groups were found in nerve morphometry. Morphometric analysis of the FD muscle revealed significant improvements in the PBM group, but with no significant differences regarding the FCR muscle. These findings suggest that 660-nm laser with the parameters used produced functional improvement as well as significant improvements in the morphometry of the FD muscle, but did not have significant effects on the morphometry of the FCR muscle or nerve regeneration.

Photobiomodulation of Na,K-ATPase in native membrane fraction and reconstituted in DPPC:DPPE-liposome

Studies focusing on how photobiomodulation (PBM) can affect the structure and function of proteins are scarce in the literature. Few previous studies have shown that the enzymatic activity of Na,K-ATPAse (NKA) can be photo-modulated. However, the variability of sample preparation and light irradiation wavelengths have not allowed for an unequivocal conclusion about the PBM of NKA. Here, we investigate minimal membrane models containing NKA, namely, native membrane fraction and DPPC:DPPE proteoliposome upon laser irradiation at wavelengths 532, 650, and 780 nm. Interestingly, we show that the PBM on the NKA enzymatic activity has a bell-shaped profile with a stimulation peak (~15% increase) at around 20 J.cm-2 and 6 J.cm-2 for the membrane-bound and the proteoliposome samples, respectively, and are practically wavelength independent. Further, by normalizing the enzymatic activity by the NKA enzyme concentration, we show that the PBM response is related to the protein amount with small influence due to protein's environment. The stimulation decays over time reaching the basal level around 6 h after the irradiation for the three lasers and both NKA samples. Our results demonstrate the potential of using low-level laser therapy to modulate NKA activity, which may have therapeutic implications and benefits.

Repeated exposure to low doses of light induces retinal damage in vivo in a wavelength-dependent manner

The exposure of the general population to artificial light at night has dramatically increased in recent decades. Current standards for domestic lighting are based on acute exposure to light and consider blue wavelengths to be responsible for phototoxicity. However, meta-analyses pointed out the role of lifelong light exposure in the onset of age-related macular degeneration, suggesting a cumulative effect of light exposure. Here, we investigate the retinal phototoxicity of a repeated exposure to light emitting diodes of different spectral compositions in 6-week-old albino rats. Rats were exposed twice a day for 15 days to retinal doses that were safe in acute exposure (0.1 and 0.2 J/cm² for blue and white lights, 0.2 J/cm² for green light and 0.05 J/cm² for red light). We show that rats repeatedly exposed to blue and white lights display irreversible retinal damage, characterized by a degradation of the global retinal structure, a significant photoreceptor loss, and an increase of stress and inflammation markers. We highlight the role of green wavelengths in the phototoxicity of white light and show the protective effect of the addition of red light to mitigate the phototoxicity of blue light. All of this points out the need to rethink the current phototoxicity standards by taking into account the cumulative effect of the exposure to light and the role of the different parts of the emission spectrum.

Effect of Laser Photobiomodulation on Postoperative Pain After Single-Visit Endodontic Treatment in Children: A Randomized Control Trial

BACKGROUND

This study aimed to assess the effectiveness of laser photobiomodulation (PBM) in reducing postoperative pain following single-visit endodontic treatment in children aged 5-9 years.

METHODS

Forty children aged 5-9 years with acute irreversible pulpitis in deciduous molars requiring single-visit pulpectomy were included in the study. Pulpectomy was performed according to a standard endodontic protocol. The participants were randomly allocated to two groups: group A received laser photobiomodulation using an 810 nm diode laser applied to the periapical area of the treated tooth postoperatively, and group B received blue light LED, applied at similar points to the control teeth. This was a placebo intervention. Pain scores were measured using a 10-point Visual Analog Scale (VAS) at 4, 12, 24, and 48 h post-treatment. The Friedman test was used to compare the VAS scores within groups over time, and the Mann-Whitney U-test was used to compare the VAS scores between the two groups. The significance level was fixed at p < 0.05.

RESULT

The mean VAS scores were significantly lower in the PBM group compared to the placebo group at the 4th h, 12th h, and 24th h post-treatment (p ≤ 0.05). The pain levels remained stable over time in the PBM group, with no significant difference in pain scores from 4 h to 48 h (p = 0.57). In the placebo group, the pain gradually decreased from the 4th h to the 48th h, with a significant reduction in pain observed between the 12th h and 48th h (p = 0.05).

CONCLUSIONS

Laser photobiomodulation (PBM) was found to be effective in reducing postoperative pain following single-visit endodontic treatment in children. This non-invasive approach could offer a valuable alternative for pain management in pediatric endodontics, particularly given its effectiveness without the need for systemic medications.

Photobiomodulation for diabetes and its complications: a review of general presentation, mechanisms and efficacy

Diabetes mellitus is a metabolic disease that is marked by persistent hyperglycemia due to inadequate insulin secretion or insulin resistance. Its prevalence is increasing yearly. Diabetes mellitus can lead to serious health complications that are the primary cause of mortality and disability among diabetic patients, including diabetic retinopathy, diabetic foot ulcers, diabetic peripheral neuropathy, and diabetic periodontitis, and so on. Traditional treatments for diabetes and its complications still suffer from limited clinical efficacy and high therapeutic side effects. Photobiomodulation (PBM), which utilizes low levels of red or near-infrared laser to irradiate cells and tissues, has been shown to be efficacious for a wide range of organ damage. In this study, we focus on the application of PBM in diabetes and its complications and mechanisms, as well as the advantages, disadvantages with the aim of developing new ideas for the application of PBM.

The Impact of Low-Level Laser Therapy on Spasticity in Children with Spastic Cerebral Palsy: A Systematic Review

CONTEXT

Spastic cerebral palsy (SCP) is a condition characterized by muscle stiffness and involuntary movements, which greatly affect movement abilities and overall well-being. Low-level laser therapy (LLLT) has emerged as a treatment option for managing spasticity, though the current evidence varies.

OBJECTIVE

This systematic review seeks to assess the efficacy of LLLT on spasticity in children with cerebral palsy. We hope it will pinpoint areas where more research is needed and suggest directions for future studies.

METHOD

A search of the literature was performed across databases, such as PubMed, Google Scholar, Scopus, and Elicit. The search utilized keywords and the Medical Subject Headings (MeSH) terms. Only studies conducted in English that focused on children with cerebral palsy (CP) and explored the effects of LLLT on spasticity were considered. The quality of the selected studies was evaluated using assessment tools.

RESULTS

The search identified 534 references, out of which eight studies met the screening criteria for inclusion. All cited papers indicated reductions in spasticity with further mention of reduced pain and greater muscle strength by some authors.

CONCLUSIONS

This review indicates that LLLT shows promise in decreasing spasticity in children with cerebral palsy. Nevertheless, a lack of treatment parameters, heterogeneity in research methods, and a lack of objective outcome measures weaken the results. This review underscores the importance of standardized procedures and carefully planned randomized controlled trials to establish conclusive findings on the effectiveness of LLLT in this population.

Investigating the safety of photobiomodulation in oral carcinogenesis: insights into cell proliferation, invasion, and apoptosis via the 4NQO model

The present investigation aimed to assess the safety of photobiomodulation (PBM) on the oral carcinogenesis process induced by 4NQO, focusing on cell proliferation and apoptosis. Sixty-six Wistar rats received systemic 4NQO for 12 (n = 33) and 20 weeks (n = 33), divided into Control group, PBM 0.3 J, and PBM 1 J. Applications for PBM occurred three times a week. At weeks 12 and 20, the animals were euthanized. The immunoreactivity for anti-ROS1 and anti-p53 antibodies was also assessed. Statistical analysis was assessed by multiple t-tests, Kruskal-Wallis, and Spearman's correlation. At 12 weeks, PBM 1 J group had nodular lesions, distinct from control and PBM 0.3 J groups (p = 0.005). At 20 weeks, nodular lesions were common in control and PBM 0.3 J groups. Histopathological characteristics did not significantly differ between groups at 12 (p = 0.30) and 20 weeks (p = 0.58). Epithelial dysplasia (n = 21) was common at 12 weeks. After 20 weeks, most of the cases revealed squamous cell carcinoma (n = 24). No differences were observed in the immunostaining of p53 and ROS1 among the control and experimental groups and there was no correlation of these proteins with clinicopathological data. During the carcinogenesis process, the PBM did not modify the development of oral lesions and the expression of proliferative and apoptosis proteins.

Long-term safety of photobiomodulation exposure to beta cell line and rat islets in vitro and in vivo

This study evaluates the safety and potential benefits of PBM on pancreatic beta cells and islets. PBM was applied to insulin-secreting cell lines (MIN6) and rat pancreatic islets using a 670 nm light source, continuous output, with a power density of 2.8 mW/cm², from 5 s to several 24 h. Measure of cell viability, insulin secretion, mitochondrial function, ATP content, and cellular respiration were assessed. Additionally, a diabetic rat model is used for islet transplantation (pre-conditioning with PBM or not) experiments. Short and long-term PBM exposure did not affect beta cell islets viability, insulin secretion nor ATP content. While short-term PBM (2 h) increases superoxide ion content, this was not observed for long exposure (24 h). Mitochondrial respirations were slightly decreased after PBM. In the islet transplantation model, both pre-illuminated and non-illuminated islets improved metabolic control in diabetic rats with a safety profile regarding the post-transplantation period. In summary, for the first time, long-term PBM exhibited safety in terms of cell viability, insulin secretion, energetic profiles in vitro, and post-transplantation period in vivo. Further investigation is warranted to explore PBM's protective effects under conditions of stress, aiding in the development of innovative approaches for cellular therapy.

Impact of photobiomodulation therapy on pro-inflammation functionality of human peripheral blood mononuclear cells - a preliminary study

Research into the efficacy of photobiomodulation therapy (PBMT) in reducing inflammation has been ongoing for years, but standards for irradiation methodology still need to be developed. This study aimed to test whether PBMT stimulates in vitro human peripheral blood mononuclear cells (PBMCs) to synthesize pro-inflammatory cytokines, including chemokines. PBMCs were irradiated with laser radiation at two wavelengths simultaneously (λ = 808 nm in continuous emission and λ = 905 nm in pulsed emission). The laser radiation energy was dosed in one dose as a whole (5 J, 15 J, 20 J) or in a fractionated way (5 J + 15 J and 15 J + 5 J) with a frequency of 500, 1,500 and 2,000 Hz. The surface power densities were 177, 214 and 230 mW/cm2, respectively. A pro-inflammatory effect was observed at both the transcript and protein levels for IL-1β after PBMT at the energy doses 5 J and 20 J (ƒ=500 Hz) and only at the transcript level after application of PBMT at energy doses of 20 J (ƒ= 1,500; ƒ=2,000 Hz) and 5 + 15 J (ƒ=500 Hz). An increase in CCL2 and CCL3 mRNA expression was observed after PBMT at 5 + 15 J (ƒ=1,500 Hz) and 15 + 5 J (ƒ=2,000 Hz) and CCL3 concentration after application of an energy dose of 15 J (frequency of 500 Hz). Even though PBMT can induce mRNA synthesis and stimulate PBMCs to produce selected pro-inflammatory cytokines and chemokines, it is necessary to elucidate the impact of the simultaneous emission of two wavelengths on the inflammatory response mechanisms.

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.

Study and optimization of the photobiomodulation effects induced on mitochondrial metabolic activity of human cardiomyocytes for different radiometric and spectral conditions

Photobiomodulation (PBM) represents a promising and powerful approach for non-invasive therapeutic interventions. This emerging field of research has gained a considerable attention due to its potential for multiple disciplines, including medicine, neuroscience, and sports medicine. While PBM has shown the ability to stimulate various cellular processes in numerous medical applications, the fine-tuning of treatment parameters, such as wavelength, irradiance, treatment duration, and illumination geometry, remains an ongoing challenge. Furthermore, additional research is necessary to unveil the specific mechanisms of action and establish standardized protocols for diverse clinical applications. Given the widely accepted understanding that mitochondria play a pivotal role in the PBM mechanisms, our study delves into a multitude of PBM illumination parameters while assessing the PBM's effects on the basis of endpoints reflecting the mitochondrial metabolism of human cardiac myocytes (HCM), that are known for their high mitochondrial density. These endpoints include: i) the endogenous production of protoporphyrin IX (PpIX), ii) changes in mitochondrial potential monitored by Rhodamine 123 (Rhod 123), iii) changes in the HCM's oxygen consumption, iv) the fluorescence lifetime of Rhod 123 in mitochondria, and v) alterations of the mitochondrial morphology. The good correlation observed between these different methods to assess PBM effects underscores that monitoring the endogenous PpIX production offers interesting indirect insights into the mitochondrial metabolic activity. This conclusion is important since many approved therapeutics and cancer detection approaches are based on the use of PpIX. Finally, this correlation strongly suggests that the PBM effects mentioned above have a common "fundamental" mechanistic origin.

Outstanding user reported satisfaction for light emitting diodes under-eye rejuvenation

The under-eye region is an area of significant cosmetic concern. Photobiomodulation (PBM) has emerged as an effective, safe, inexpensive, and convenient treatment for skin rejuvenation. Herein, we aim to evaluate the safety and efficacy of a LED under-eye device for under-eye rejuvenation, as measured by objective and patient reported outcomes. Eleven participants self-administered treatment using a commercially available LED device emitting red (633 nm) and near infrared (830 nm) light for six weeks. Standardized photographs and questionnaires were administered at baseline and six weeks. Photographic digital analysis indicated an improvement in under-eye wrinkles at six weeks compared to baseline, with a reduction in wrinkle score from 20.05 to 19.72. However, this finding was not statistically significant. Participants self-reported consistent improvements in under-eye wrinkles, texture, dark circles, bags, pigmentation, and erythema. All participants reported a high degree of comfortability, ease of use, and satisfaction with the eye device. The participants noted no moderate or severe adverse events and few reports of transient expected outcomes such as mild erythema. The participants' self-reported improvements and high user satisfaction, and the device's favorable safety profile, highlights the benefits of at-home LED devices for under-eye rejuvenation. Future randomized controlled trials with larger sample sizes could further establish the safety and efficacy of at-home LED under-eye treatments.

Physical Treatments and Therapies for Androgenetic Alopecia

Androgenetic alopecia, the most common cause of hair loss affecting both men and women, is typically treated using pharmaceutical options, such as minoxidil and finasteride. While these medications work for many individuals, they are not suitable options for all. To date, the only non-pharmaceutical option that the United States Food and Drug Administration has cleared as a treatment for androgenetic alopecia is low-level laser therapy (LLLT). Numerous clinical trials utilizing LLLT devices of various types are available. However, a myriad of other physical treatments for this form of hair loss have been reported in the literature. This review evaluated the effectiveness of microneedling, pulsed electromagnetic field (PEMF) therapy, low-level laser therapy (LLLT), fractional laser therapy, and nonablative laser therapy for the treatment of androgenetic alopecia (AGA). It also explores the potential of multimodal treatments combining these physical therapies. The majority of evidence in the literature supports LLLT as a physical therapy for androgenetic alopecia. However, other physical treatments, such as nonablative laser treatments, and multimodal approaches, such as PEMF-LLLT, seem to have the potential to be equally or more promising and merit further exploration.

Photobiomodulation with laser and led on mesenchymal stem cells viability and wound closure in vitro

Mesenchymal stem cells can differentiate into specific cell lineages in the tissue repair process. Photobiomodulation with laser and LED is used to treat several comorbidities, can interfere in cell proliferation and viability, in addition to promoting responses related to the physical parameters adopted. Evaluate and compare the effects of laser and LED on mesenchymal cells, with different energy doses and different wavelengths, in addition to viability and wound closure. Mesenchymal stem cells derived from human adipocytes were irradiated with laser (energy of 0.5 J, 2 J and 4 J, wavelength of 660 nm and 830 nm), and LED (energy of 0.5 J, 2 J and 4 J, where lengths are 630 nm and 850 nm). The wound closure process was evaluated through monitoring the reduction of the lesion area in vitro. Viability was determined by analysis with Hoechst and Propidium Iodide markers, and quantification of viable and non-viable cells respectively Data distributions were analyzed using the Shapiro-Wilk test. Homogeneity was analyzed using Levene's test. The comparison between the parameters used was analyzed using the Two-way ANOVA test. The T test was applied to data relating to viability and lesion area. For LED photobiomodulation, only the 630 nm wavelength obtained a significant result in 24, 48 and 72 h (p = 0,027; p = 0,024; p = 0,009). The results related to the in vitro wound closure test indicate that both photobiomodulation with laser and LED demonstrated significant results considering the time it takes to approach the edges (p < 0.05). Considering the in vitro experimental conditions of the study, it is possible to conclude that the physical parameters of photobiomodulation, such as energy and wavelength, with laser or LED in mesenchymal stem cells, can play a potential role in cell viability and wound closure.

Protective Effect of Red Light-Emitting Diode against UV-B Radiation-Induced Skin Damage in SKH:HR-2 Hairless Mice

In this in vivo study on hairless mice, we examined the effects of light-emitting diode (LED) treatment applied prior to ultraviolet B (UVB) irradiation. We found that pre-treating with LED improved skin morphological and histopathological conditions compared to those only exposed to UVB irradiation. In our study, histological evaluation of collagen and elastic fibers after LED treatment prior to UVB irradiation showed that this pretreatment significantly enhanced the quality of fibers, which were otherwise poor in density and irregularly arranged due to UV exposure alone. This suggests that LED treatment promotes collagen and elastin production, leading to improved skin properties. Additionally, we observed an increase in Claudin-1 expression and a reduction in nuclear factor-erythroid 2-related factor 2 (Nrf-2) and heme-oxygenase 1 (HO-1) expression within the LED-treated skin tissues, suggesting that LED therapy may modulate key skin barrier proteins and oxidative stress markers. These results demonstrate that pretreatment with LED light can enhance the skin's resistance to UVB-induced damage by modulating gene regulation associated with skin protection. Further investigations are needed to explore the broader biological effects of LED therapy on other tissues such as blood vessels. This study underscores the potential of LED therapy as a non-invasive approach to enhance skin repair and counteract the effects of photoaging caused by UV exposure.

Diabetes in spotlight: current knowledge and perspectives of photobiomodulation utilization

Introduction

Diabetes is a global health concern characterized by chronic hyperglycemia resulting from insulinopenia and/or insulin resistance. The rising prevalence of diabetes and its associated complications (ulcers, periodontitis, healing of bone defect, neuropathy, retinopathy, cardiopathy and nephropathy) necessitate innovative therapeutic approaches. Photobiomodulation (PBM), involves exposing tissues and cells to low-energy light radiation, leading to biological effects, largely via mitochondrial activation.

Methods

This review evaluates preclinical and clinical studies exploring the potential of PBM in diabetes and its complications, as well all clinical trials, both planned and completed, available on ClinicalTrials database.

Results

This review highlights the variability in PBM parameters across studies, hindering consensus on optimal protocols. Standardization of treatment parameters and rigorous clinical trials are needed to unlock PBM's full therapeutic potential. 87 clinical trials were identified that investigated PBM in diabetes mellitus (with 5,837 patients planned to be treated with PBM). Clinical trials assessing PBM effects on diabetic neuropathy revealed pain reduction and potential quality of life improvement. Studies focusing on wound healing indicated encouraging results, with PBM enhancing angiogenesis, fibroblast proliferation, and collagen density. PBM's impact on diabetic retinopathy remains inconclusive however, requiring further investigation. In glycemic control, PBM exhibits positive effects on metabolic parameters, including glucose tolerance and insulin resistance.

Conclusion

Clinical studies have reported PBM-induced reductions in fasting and postprandial glycemia without an increased hypoglycemic risk. This impact of PBM may be related to its effects on the beta cells and islets in the pancreas. Notwithstanding challenges, PBM emerges as a promising adjunctive therapy for managing diabetic neuropathy, wound healing, and glycemic control. Further investigation into its impact on diabetic retinopathy and muscle recovery is warranted.

Non-lethal exposure to short-wavelength light-emitting diodes modulates tight-junction structure in human corneal epithelial cells via cAMP-dependent signaling

Light-emitting diodes (LED)-derived lights have been widely used as a medical treatment in photobiomodulation (PBM). However, the PBM effects in ophthalmology are less well investigated. Herein, we explored the effect of LED-generated light on the tight-junction (TJ) formation in human corneal epithelial cells (HCEs). The HCEs were separately exposed to monochromatic LEDs at wavelengths of 365 nm (UVA), 420 nm (violet), 470 nm (blue), 530 nm (green), 590 nm (amber), 660 nm (deep red), and 740 nm (far red) at 10 J/cm2/day for 1 and 2 days. Long-term cultivation of HCEs without LED exposure for up to 14 days was established as a control. The effects of both LED wavelength and culture duration on cell morphology, cAMP-regulated proteins, TJ-associated proteins, and cell growth-associated proteins were also analyzed. Together with the increase in cell number during prolonged cultivation, cAMP, ZO-1, ZO-2, CLDN1, and CLDN4 all increased significantly during long-term cultivation without LED exposure. There was no difference in HCE viability after exposure to all monochromatic LEDs at an accumulated dose of 20 J/cm2. As determined by immunoblotting, UVA, violet, and blue light increased intracellular cAMP, ZO-1, ZO-2, CLDN1, and CLDN4 expression, respectively. UVA and violet, but not blue, light increased PKAreg-pS77 expression. However, none of the other treatments changed the expression of PKAcat-pT197, VASP-pS157, Bax, Bcl-2, or Bcl-xL. Immunofluorescence staining confirmed the formation of TJ structures. The expressions of ZO-1, ZO-2, CLDN1, and CLDN4 as well as TJ structures 2 days following UVA, violet, and blue exposure were similar to those of control cells after 9 days of cultivation. We conclude that short-wavelength LEDs at non-lethal exposure intensities accelerated the formation of TJ structure in HCEs via a cAMP-dependent regulatory cascade.

Phototherapy for age-related brain diseases: Challenges, successes and future

Brain diseases present a significant obstacle to both global health and economic progress, owing to their elusive pathogenesis and the limited effectiveness of pharmaceutical interventions. Phototherapy has emerged as a promising non-invasive therapeutic modality for addressing age-related brain disorders, including stroke, Alzheimer's disease (AD), and Parkinson's disease (PD), among others. This review examines the recent progressions in phototherapeutic interventions. Firstly, the article elucidates the various wavelengths of visible light that possess the capability to penetrate the skin and skull, as well as the pathways of light stimulation, encompassing the eyes, skin, veins, and skull. Secondly, it deliberates on the molecular mechanisms of visible light on photosensitive proteins, within the context of brain disorders and other molecular pathways of light modulation. Lastly, the practical application of phototherapy in diverse clinical neurological disorders is indicated. Additionally, this review presents novel approaches that combine phototherapy and pharmacological interventions. Moreover, it outlines the limitations of phototherapeutics and proposes innovative strategies to improve the treatment of cerebral disorders.

The effect of adjunctive LASER application on periodontal ligament stem cells

Periodontal regeneration involves the composite action of cell, scaffolds and signaling molecules. There are numerous autologous sources of regenerative cells which are present close to the vicinity of the periodontally debilitated site, the primary one being the periodontal ligament stem cell, which is believed to have a key role in regeneration. Various methods can be harnessed to optimize and enhance the regenerative potential of PDLSCs such as the application of LASERs. In the last few years there have been various studies which have evaluated the effect of different types of LASERs on PDLSCs and the present review summarizes the photo-biomodulative activity of LASERs in general and its beneficial role in the stimulation of PDLSC specifically.

[Effect of low-intensity laser-therapy in the correction of encephalopathy in obstructive jaundice]

Hepatic encephalopathy is an early and severe complication of obstructive jaundice and is characterized by occurrence of non-focal and focal neurological manifestations. Different methods of therapy are applied for disorder correction. Low-intensity laser blood irradiation has a pronounced antioxidant and vasoactive effect.

OBJECTIVE

To analyze the results of pharmaceutical treatment and low-intensity laser therapy use in encephalopathy correction in obstructive jaundice of non-neoplastic origin.

MATERIAL AND METHODS

The study was performed at the surgery department in the S.V. Katkov Republican Clinical Hospital (Saransk). The trial included 54 patients with moderate obstructive jaundice of non-neoplastic origin with latent encephalopathy, who were divided into 2 groups: the 1st group (control) consisted of 27 patients receiving standard pharmaceutical treatment; the 2nd group (study) - 27 patients receiving standard treatment and laser therapy (low-intensity laser irradiation in red emission at the cubital vein projection for 15 minutes). A comparative group (norm) included 20 healthy volunteers. All patients underwent biochemical studies (alanine aminotransferase and total bilirubin levels in the blood were assessed) after treatment. Registration of microcirculatory disorders and psychometric testing were conducted to reveal latent hepatic encephalopathy along with the evaluation of liver functional condition.

RESULTS

Correlation analysis showed the association of psychoneurological status improvement with liver functional condition (indicators of microcirculation and biochemical blood analysis were considered) in patients receiving a comprehensive therapy with laser irradiation. Correlation coefficient amounted to 0.87-0.96 (p<0.05).

CONCLUSION

The use of above vascular laser blood irradiation in a comprehensive treatment of moderate obstructive jaundice leads to improvement of liver functional condition (the first barrier organ on the toxin pathway) and to a significant reduction of latent encephalopathy's manifestations. The conducted treatment resulted in a reduction of initially elevated levels of alanine aminotransferase and total bilirubin. Laser therapy has an ability to restore microcirculation that leads to the improvement of psychoneurological status in patients with moderate obstructive jaundice.

Shedding Light on Photobiomodulation Therapy for Age-Related Macular Degeneration: A Narrative Review

BACKGROUND

Photobiomodulation (PBM) relies on the pathophysiological mechanism whereby red to near-infrared light can target mitochondrial activity and promote ATP synthesis. Preclinical and clinical studies have shown promising results in treating intermediate age-related macular degeneration (AMD), since PBM can produce photochemical reactions in endogenous retinal chromophores. Currently, PBM is approved by the Food and Drug Administration and by the European Medicines Agency for the treatment of intermediate AMD. This narrative review aimed to evaluate the available evidence on the effectiveness and safety of PBM in treating intermediate AMD.

METHODS

A comprehensive search was conducted using the PubMed database, employing the keywords "photobiomodulation" and "age-related macular degeneration." All English-language studies published up to June 2023 were reviewed, and the search was expanded to include relevant references from selected articles. The included publications were analyzed for this review.

RESULTS

The available studies on PBM in AMD demonstrated promising but inconsistent results. PBM showed potential in improving best-corrected visual acuity (BCVA) and contrast sensitivity (CS) in patients with AMD. Some studies also suggested a reduction in AMD lesions, such as drusen volume. However, the long-term efficacy and optimal treatment parameters of PBM in AMD remained to be fully determined due to the limitations of the available studies. These included variations in irradiation techniques, wavelengths, exposure times, and treatment sessions, making it challenging to generalize the effectiveness of PBM. Furthermore, the lack of accurate classification of AMD phenotypes in the available studies hindered the understanding of which phenotypes could truly benefit from this treatment. Finally, the strength of evidence varied among studies, with limited sample sizes, unpublished results, and only three randomized sham-controlled trials.

CONCLUSIONS

Currently, the effectiveness of PBM in promoting drusen resorption or preventing progression to advanced forms of AMD, as observed in the cited studies, remains uncertain.

Male facial rejuvenation using a combination 633, 830, and 1072 nm LED face mask

Home-based photobiomodulation is a popular treatment modality for patients seeking non-invasive aesthetic treatment. Studies demonstrate that photobiomodulation is effective for skin rejuvenation, which is aimed at improving the overall appearance of the skin by reducing fine lines and wrinkles and improving skin texture, skin tone, and dyspigmentation. Most current skin rejuvenation research focuses on treatments in women. However, men's aesthetics remains an underserved market. A combined red light (RL) and near-infrared (NIR) light-emitting diode (LED) has been designed specifically to target male skin, which may have different physiological and biophysical properties compared to female skin. Herein, the safety and efficacy of a commercially available RL and NIR (633, 830, and 1072 nm) LED array designed to be worn as a face mask was assessed. Primary outcomes included adverse events and facial rejuvenation as determined by participant-reported satisfaction scales and quantitative digital skin photography and computer analysis after 6 weeks of treatment. The participants reported overall favorable results and improvements in all individual categories, were satisfied with the treatment, and would recommend the product to others. The participants perceived the greatest improvement in fine lines and wrinkles, skin texture, and youthful appearance. Photographic digital analysis demonstrated favorable improvements in wrinkles, UV spots, brown spots, pores, and porphyrins. These results support the use of RL and NIR to treat male skin. Advantages of the LED facemask include its safety, efficacy, convenient home-based use, minimal associated downtime, simple operation, non-invasiveness, and appreciable results in as few as 6 weeks.

Optogenetic Calcium Ion Influx in Myoblasts and Myotubes by Near-Infrared Light Using Upconversion Nanoparticles

Bioactuators made of cultured skeletal muscle cells are generally driven by electrical or visible light stimuli. Among these, the technology to control skeletal muscle consisting of myoblasts genetically engineered to express photoreceptor proteins with visible light is very promising, as there is no risk of cell contamination by electrodes, and the skeletal muscle bioactuator can be operated remotely. However, due to the low biopermeability of visible light, it can only be applied to thin skeletal muscle films, making it difficult to realize high-power bioactuators consisting of thick skeletal muscle. To solve this problem, it is desirable to realize thick skeletal muscle bioactuators that can be driven by near-infrared (NIR) light, to which living tissue is highly permeable. In this study, as a promising first step, upconversion nanoparticles (UCNPs) capable of converting NIR light into blue light were bound to C2C12 myoblasts expressing the photoreceptor protein channelrhodopsin-2 (ChR2), and the myoblasts calcium ion (Ca2+) influx was remotely manipulated by NIR light exposure. UCNP-bound myoblasts and UCNP-bound differentiated myotubes were exposed to NIR light, and the intracellular Ca2+ concentrations were measured and compared to myoblasts exposed to blue light. Exposure of the UCNP-bound cells to NIR light was found to be more efficient than exposure to blue light in terms of stimulating Ca2+ influx.

The mitochondrial-related effect of the 905 nm photobiomodulation therapy on 50B11 sensory neurons

Photobiomodulation therapy (PBMT) is known as a complementary tool to alleviate pain sensation in patients, nevertheless, there is still a gap of knowledge on its mechanism of action, thus limiting its clinical employment. In this study, a possible molecular mechanism of the 905 nm PBMT (0.25 W/cm2 ; 3, 6, 12, and 18 J/cm2 , 5 Hz) analgesic effect was tested on 50B11 cells, by investigating its impact on mitochondria. A decrement of adenosine triphosphate was detected, moreover, an increment of total reactive oxygen species and mitochondrial superoxide anion was found after PBMT with all protocols tested. PBMT at 18 J diminished the mitochondrial membrane potential, and influenced mitochondrial respiration, decreasing the oxygen consumption rate. Finally, a decrement of extracellular signal-regulated kinase 1/2 phosphorylation was observed with the protocol using 12 J. Taken together these findings highlighted the intracellular effects, mainly correlated to mitochondrial, induced by 905 nm PBMT in sensory neurons, indicating the central role of this organelle in the cellular response to 905 nm near-infrared laser light.

Application of combined photobiomodulation and curcumin-loaded iron oxide nanoparticles considerably enhanced repair in an infected, delayed-repair wound model in diabetic rats compared to either treatment alone

Herein, we attempted to evaluate the therapeutic potential of photobiomodulation (PBM) and curcumin-loaded iron nanoparticles (CUR), alone and in combination, on wound closure rate (WCR), microbial flora by measuring colony-forming units (CFUs), the stereological and biomechanical properties of repairing wounds in the maturation stage of the wound healing course in an ischemic infected delayed healing wound model (IIDHWM) of type I diabetic (TIDM) rats. There were four groups: group 1 was the control, group 2 received CUR, rats in group 3 were exposed to PBM (80 Hz, 890 nm, and 0.2 J/cm2), and rats in group 4 received both PBM and CUR (PBM + CUR). We found CFU was decreased in groups 2, 3, and 4 compared to group 1 (p = 0.000 for all). Groups 2, 3, and 4 showed a considerable escalation in WCR compared to group 1 (p = 0.000 for all). In terms of wound strength parameters, substantial increases in bending stiffness and high-stress load were observed in groups 2, 3, and 4 compared to group 1 (p = 0.000 for all). Stereological examinations revealed decreases in neutrophil and macrophage counts and increases in fibroblast counts in groups 2, 3, and 4compared  to group 1 (p = 0.000 for all). Blood vessel counts were more dominant in the PBM and PBM + CUR groups over group 1 (p = 0.000 for all). CFU and wound strength as well as macrophage, neutrophil, and fibroblast counts were found to be improved in the PBM + CUR and PBM groups compared to the CUR group (ranging from p = 0.000 to p < 0.05). Better results were achieved in the PBM + CUR  treatment  over the PBM therapy. We determined therapy with PBM + CUR, PBM alone, and CUR alone substantially accelerated diabetic wound healing in an IIDHWM of TIDM rats compared to control  group. Concomitantly, the PBM + CUR and PBM groups attained significantly enhanced results for WCR, stereological parameters, and wound strength than the CUR group, with the PBM + CUR results being superior to those of the PBM group.

Photobiomodulation: A Systematic Review of the Oncologic Safety of Low-Level Light Therapy for Aesthetic Skin Rejuvenation

Photobiomodulation (PBM) therapy is an increasingly popular modality for aesthetic skin rejuvenation. PBM induces genomic, proteomic, and metabolomic processes within target cells, but such manipulation of cell behavior has led to concerns about oncologic safety. This article presents a summary of the clinical and preclinical evidence for the oncologic safety of PBM for aesthetic skin rejuvenation. A focused systematic review was performed, in which safety data from clinical trials of PBM for skin rejuvenation was supplemented by analyses of in vitro data obtained from cells derived from human skin and human neoplastic cells and in vivo data of tumors of the skin, oral cavity, and breast. Within established parameters, red and near infrared light mainly enhances proliferation of healthy cells without a clear pattern of influence on cell viability. The same light parameters mainly reduce neoplastic cell proliferation and viability or else make no difference. Invasiveness potential (appraised by cell migration assays and/or differential gene expression) is equivocal. PBM does not induce dysplastic change in healthy cells. In vivo tumor models yield varied results with no clear pattern emerging. There are no relevant clinical trial data linking PBM with any significant adverse events, including the finding of a new or recurrent malignancy.Current clinical and preclinical evidence suggests that PBM is oncologically safe for skin rejuvenation, and there is no evidence to support the proposition that it should be avoided by patients who have previously undergone treatment for cancer.

LEVEL OF EVIDENCE: 4

Effectiveness of non-pharmacological therapies on cognitive function in patients with dementia-A network meta-analysis of randomized controlled trials

Objective

Non-pharmacological therapies (NPTs) have received increasing attention from researchers as a category of treatment to improve cognitive impairment in patients with dementia because of their fewer side effects. In this study, photobiomodulation (PBM), enriched environment (EE), exercise therapy (ET), computerized cognitive training (CCT), and cognitive stimulation therapy (CST) were selected to compare the effects of NPTs that improve dementia by quantifying information from randomized controlled trials (RCTs).

Methods

We did a systematic review and network meta-analysis. We searched PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), China National Knowledge Infrastructure Database, Wan Fang Database, Chinese Biomedical Literature Database, Web of Science, and VIP Database from the time of database creation to 1 August 2022. Two investigators independently screened the literature, extracted information, and assessed the RCTs' quality with the Cochrane Collaboration Network Risk of Bias 2.0. Network meta-analysis was performed using R language (X64 version 4.1.3) and STATA 17.0.

Results

We identified 1,268 citations and of these included 38 trials comprising 3,412 participants. For improving dementia, the results of the network meta-analysis showed that compared with the control group (CON), PBM (SMD = 0.90, 95% CI: 0.43-1.37), EE (SMD = 0.71, 95% CI: 0.02-1.41), ET (SMD = 0.42, 95% CI: 0.16-0.68), and CST (SMD = 0.36, 95% CI: 0.11-0.62) were significantly different (P < 0.05); There was no significant difference in CCT (SMD = 0.41, 95% CI: -0.07-0.88) (P > 0.05). The ranked results showed that PBM has more potential to be the best intervention (P = 0.90). In addition, there was a significant difference between PBM and CST in improving cognitive function (SMD = 0.54, 95% CI: 0.00; 1.08, P < 0.05).

Conclusion

In this study, NPTs have excellent potential to improve cognition in people with dementia, and PBM may have more significant benefits in improving cognition than the other four NPTs.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022363746.

Photobiomodulation Reduces Periocular Wrinkle Volume by 30%: A Randomized Controlled Trial

Objective: This study aimed to evaluate red and amber light-emitting diode protocols for facial rejuvenation at the same light dose. Background: The demand for minimally invasive cosmetic procedures to address skin aging has grown throughout the world. In vitro red and amber photobiomodulation (PBM) has been shown to improve collagen synthesis. Meanwhile, red PBM has already been studied in clinical trials; however, a comparison of the use of different wavelengths at the same light dose to reduce periocular wrinkles has not yet been performed. Methods: This split-face, randomized clinical trial recruited 137 women (40-65 years old) presenting with skin phototypes II-IV and Glogau photoaging scale types II-IV. The individuals received 10 sessions for 4 weeks of red (660 nm) and amber (590 nm) PBM (3.8 J/cm²), one at each side of the face. The outcomes, measured before and after the treatments, were the periocular wrinkle volume measured by VisioFace^® RD equipment; hydration measured by the Corneometer CM 825; skin elasticity measured by the Cutometer Dual MPA 580; and quality of life determined by adapted versions of validated questionnaires [Melasma Quality of Life Scale-Brazilian Portuguese (MelasQoL-BP) and Skindex-29]. Results: There was a significant reduction in wrinkle volume after red (31.6%) and amber (29.9%) PBM. None of the treatments improved skin hydration and viscoelasticity. Both questionnaires showed improvements in participants' quality of life. Conclusions: PBM, both at red and amber wavelengths, is an effective tool for rejuvenation, producing a 30% wrinkle volume reduction. The technique has strong potential in patients with diabetes or those presenting with keloids, conditions for which highly inflammatory rejuvenating procedures are not indicated. Clinical trial registration number: REBEC-6YFCBM.

Next-Generation Examination, Diagnosis, and Personalized Medicine in Periodontal Disease

Periodontal disease, a major cause of tooth loss, is an infectious disease caused by bacteria with the additional aspect of being a noncommunicable disease closely related to lifestyle. Tissue destruction based on chronic inflammation is influenced by host and environmental factors. The treatment of periodontal disease varies according to the condition of each individual patient. Although guidelines provide standardized treatment, optimization is difficult because of the wide range of treatment options and variations in the ideas and skills of the treating practitioner. The new medical concepts of “precision medicine” and “personalized medicine” can provide more predictive treatment than conventional methods by stratifying patients in detail and prescribing treatment methods accordingly. This requires a new diagnostic system that integrates information on individual patient backgrounds (biomarkers, genetics, environment, and lifestyle) with conventional medical examination information. Currently, various biomarkers and other new examination indices are being investigated, and studies on periodontal disease-related genes and the complexity of oral bacteria are underway. This review discusses the possibilities and future challenges of precision periodontics and describes the new generation of laboratory methods and advanced periodontal disease treatment approaches as the basis for this new field.

Control of actin polymerization via reactive oxygen species generation using light or radiation

Actin is one of the most prevalent proteins in cells, and its amino acid sequence is remarkably conserved from protozoa to humans. The polymerization-depolymerization cycle of actin immediately below the plasma membrane regulates cell function, motility, and morphology. It is known that actin and other actin-binding proteins are targets for reactive oxygen species (ROS), indicating that ROS affects cells through actin reorganization. Several researchers have attempted to control actin polymerization from outside the cell to mimic or inhibit actin reorganization. To modify the polymerization state of actin, ultraviolet, visible, and near-infrared light, ionizing radiation, and chromophore-assisted light inactivation have all been reported to induce ROS. Additionally, a combination of the fluorescent protein KillerRed and the luminescent protein luciferase can generate ROS on actin fibers and promote actin polymerization. These techniques are very useful tools for analyzing the relationship between ROS and cell function, movement, and morphology, and are also expected to be used in therapeutics. In this mini review, we offer an overview of the advancements in this field, with a particular focus on how to control intracellular actin polymerization using such optical approaches, and discuss future challenges.

Full-Body Photobiomodulation Therapy Is Associated with Reduced Sleep Durations and Augmented Cardiorespiratory Indicators of Recovery

Research is emerging on the use of Photobiomodulation therapy (PBMT) and its potential for augmenting human performance, however, relatively little research exists utilizing full-body administration methods. As such, further research supporting the efficacy of whole-body applications of PBMT for behavioral and physiological modifications in applicable, real-world settings are warranted. The purpose of this analysis was to observe cardiorespiratory and sleep patterns surrounding the use of full-body PBMT in an elite cohort of female soccer players. Members of a women’s soccer team in a “Power 5 conference” of the National Collegiate Athletic Association (NCAA) were observed across one competitive season while wearing an OURA Ring nightly and a global positioning system (GPS) sensor during training. Within-subject comparisons of cardiorespiratory physiology, sleep duration, and sleep composition were evaluated the night before and after PBMT sessions completed as a standard of care for team recovery. Compared to pre-intervention, mean heart rate (HR) was significantly lower the night after a PBMT session (p = 0.0055). Sleep durations were also reduced following PBMT, with total sleep time (TST) averaging 40 min less the night after a session (p = 0.0006), as well as significant reductions in light sleep (p = 0.0307) and rapid eye movement (REM) sleep durations (p = 0.0019). Sleep durations were still lower following PBMT, even when controlling for daily and accumulated training loads. Enhanced cardiorespiratory indicators of recovery following PBMT, despite significant reductions in sleep duration, suggest that it may be an effective modality for maintaining adequate recovery from the high stress loads experienced by elite athletes.

Therapeutic Potential of Photobiomodulation for Chronic Kidney Disease

Chronic kidney disease (CKD) is a growing global public health problem. The implementation of evidence-based clinical practices only defers the development of kidney failure. Death, transplantation, or dialysis are the consequences of kidney failure, resulting in a significant burden on the health system. Hence, innovative therapeutic strategies are urgently needed due to the limitations of current interventions. Photobiomodulation (PBM), a form of non-thermal light therapy, effectively mitigates mitochondrial dysfunction, reactive oxidative stress, inflammation, and gut microbiota dysbiosis, all of which are inherent in CKD. Preliminary studies suggest the benefits of PBM in multiple diseases, including CKD. Hence, this review will provide a concise summary of the underlying action mechanisms of PBM and its potential therapeutic effects on CKD. Based on the findings, PBM may represent a novel, non-invasive and non-pharmacological therapy for CKD, although more studies are necessary before PBM can be widely recommended.

Photobiomodulation with a 660-Nanometer Light-Emitting Diode Promotes Cell Proliferation in Astrocyte Culture

Astrocytes act as neural stem cells (NSCs) that have the potential to self-renew and differentiate into other neuronal cells. The protein expression of these astrocytes depends on the stage of differentiation, showing sequential expression of multiple proteins such as octamer-binding transcription factor 4 (Oct4), nestin, glial fibrillary acidic protein (GFAP), and aldehyde dehydrogenase 1 family member L1 (aldh1L1). Photobiomodulation (PBM) affects cell apoptosis, proliferation, migration, and adhesion. We hypothesized that astrocyte proliferation and differentiation would be modulated by PBM. We used an optimized astrocyte culture method and a 660-nanometer light-emitting diode (LED) to enhance the biological actions of many kinds of cells. We determined that the 660-nanometer LED promoted the biological actions of cultured astrocytes by increasing the reactive oxygen species levels. The overall viability of the cultured cells, which included various cells other than astrocytes, did not change after LED exposure; however, astrocyte-specific proliferation was observed by the increased co-expression of GFAP and bromodeoxyuridine (BrdU)/Ki67. Furthermore, the 660-nanometer LED provides evidence of differentiation, as shown by the decreased Oct4 and GFAP co-expression and increased nestin and aldh1L1 expression. These results demonstrate that a 660-nanometer LED can modify astrocyte proliferation, which suggests the efficacy of the therapeutic application of LED in various pathological states of the central nervous system.