Review on the Cellular Mechanisms of Low-Level Laser Therapy Use in Oncology

Opto-Laser-Responsive Smart NanoGel with Mild Hyperthermia, Vascularization, and Anti-Inflammatory Potential for Boosting Hard-to-Heal Wounds in a Diabetic Mice Model

It is well known that impaired wound healing associated with diabetes mellitus has led to a challenging problem as well as a global economic healthcare burden. Conventional wound care therapies like films, gauze, and bandages fail to cure diabetic wounds, thereby demanding a synergistic and promising wound care therapy. This investigation aimed to develop a novel, greener synthesis of a laser-responsive silver nanocolloid (LR-SNC) prepared using hyaluronic acid as a bioreductant. The prepared LR-SNC was embedded into a stimuli-responsive in situ gel (LR-SNC-in situ gel) for easy application to the wound region. The physicochemical characterization of LR-SNC revealed a nanometric hydrodynamic particle size of 25.59 ± 0.72 nm with an -31.8 ± 0.7 mV surface ζ-potential. The photothermal conversion efficiency of LR-SNC was observed up to 62.9 ± 0.1 °C. In vitro evaluation of LR-SNC with and without NIR laser irradiation exhibited >70% cell viability, confirming its cytocompatibility for human keratinocyte cells. The in vitro scratch assay showed significant wound closure of 75.50 ± 0.02%. Further, the addition of cytocompatible LR-SNC into an in situ gel followed by laser irradiation resulted in substantial in vivo wound closure (86.69 ± 2.48%) in a diabetic wound-bearing mouse. Histological evaluation demonstrated salient features of the healed wounds, such as increased neovascularization, collagen density, migration of keratinocytes, as well as growth of hair follicles. Additionally, the findings showed a decrease in the levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and enhanced angiogenesis gene expression (VEGF and CD31), thereby healing the diabetic wound efficiently. The present study confirmed the potential role of silver nanocolloids followed by laser irradiation in treating diabetic wound mouse models.

Molecular evidence for the efficacy of PBM therapy in the treatment of oral lichen planus

PURPOSE

Oral lichen planus (OLP) is a chronic inflammatory disease, in which T-Lymphocytes induce apoptosis of basal keratinocytes, leading to the formation of symptomatic lesions. It is assumed that blocking the cell death program and enhancing cell proliferation would be crucial to the healing process. The aim of the study was to verify the efficacy of Photobiomodulation (PBM) in OLP management, by evaluating the effects of laser irradiation on the processes of apoptosis and cell proliferation.

METHODS

Twenty patients with OLP underwent PBM with 810 nm diode laser (0.5 W, 30 s, 1.2 J/cm2), 3 times a week for one month. The size and clinical scores of the lesions and pain level were recorded and compared before and after therapy using Thongprasom sign scoring system and Visual Analogue Scale, respectively. Biopsies were taken before and after therapy and analyzed immunohistochemically for bcl-2 and Ki-67 expression. Tissue sections from 10 healthy volunteers were used as controls for the levels of these markers in normal oral mucosa.

RESULTS

PBM significantly reduced patients' pain intesity and improved the clinical signs of the lesions. OLP tissue sections demonstrated lower staining for bcl-2 and Ki-67 compared to healthy controls. After therapy the expression of bcl-2 increased significantly. An enhance in Ki-67 immunoreactivity was revealed predominantly in the atrophic-erosive epithelium.

CONCLUSION

PBM is an effective treatment modality for OLP patients. Erosive forms of the disease responded better to laser irradiation than keratotic subtypes. At the molecular level, PBM is likely to recover the impaired cell cycle mechanisms and keratinocyte proliferation.

Influence of Photobiomodulation Therapy Combined with Pelvic Floor Exercises on Postpartum Coccydynia: A Randomized Controlled Trial

Objective: This study was conducted to investigate whether the addition of photobiomodulation therapy (PBMT) to pelvic floor exercises (PFEs) is more effective in treating postpartum coccydynia compared with either modality alone. Background: Postpartum coccydynia is a widespread condition that significantly affects the quality of life. Inflammation as a response to childbirth trauma and weakening of the muscles and ligaments attached to the coccyx are presumed causes of postpartum coccydynia. Finding effective modalities to manage this condition will help the quality of life for most women. Methods: Sixty women aged 25-35 years with postpartum coccydynia ≥6 weeks were randomly allocated to Group A (PBMT + hot pack + PFEs), Group B (PBMT + hot pack), and Group C (placebo PBMT + hot pack + PFEs). All groups received 12 sessions over 4 weeks of hot packs plus their allocated active treatment (PBMT and/or PFEs). Outcomes were pain intensity (visual analog scale), lumbar flexion range of motion (ROM) (modified Schober test), and self-reported disability (Oswestry Disability Index). The assessors were blinded to group allocation. Results: All the measured outcomes showed significant differences (p < 0.001), with the superiority of Group A over the other groups (p < 0.001). Within groups, all groups showed statistically significant improvement from baseline across outcomes (p < 0.05). Conclusions: Adding PBMT to PFEs is recommended in the management of postpartum coccydynia as this combination resulted in greater reductions in pain and disability, along with improved lumbar flexion ROM.

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.

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.

Effect of nutritional stress and photobiomodulation protocol on in vitro viability and proliferation of murine preosteoblast cells

This study aimed to assess the impact of nutritional conditions and irradiation parameters on the viability and proliferation of murine preosteoblasts. MC3T3-E1 cells were maintained under standard culture conditions (αMEM supplemented with 10% fetal bovine serum) or nutritional deficit conditions (αMEM without serum) and irradiated or not (control) with an InGaAlP diode laser at wavelengths of 660 nm (red) or 790 nm (infrared), with doses of 1, 4, or 6 J/cm², in a single dose in continuous mode. Cell viability and proliferation were assessed 24, 48, and 72 h after irradiation using the Alamar blue reduction assay. The cell cycle and events related to cell death were evaluated via propidium iodide (PI) staining and Annexin V/PI assays, respectively, through flow cytometry. The data revealed that in cells cultured with normal nutrition (10% FBS), there was no significant difference (p > 0.05) in cell viability or proliferation among the different irradiation protocols. In contrast, in the experiments conducted under nutritional deficiency, the infrared laser at a dose of 6 J/cm² significantly increased (p < 0.05) cell viability and proliferation compared with those of the control group at 72 h. The data were confirmed by cell cycle and cell death events (Annexin V/PI) assays. These results suggest that in vitro PBM yields more consistent biostimulatory effects on pre-osteoblasts subjected to nutritional deficiency, highlighting the need for attention to simulate these conditions in studies with laser therapy in in vitro bone disease models and in in vitro experiments using PBM for bone tissue engineering.

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.

Effect of Low-Level Laser Irradiation on the Proliferation of Human Chondrocytes: An In Vitro Study

Introduction: Chondrocytes are the major cell in hyaline cartilage playing a crucial role in maintaining the mechanical resilience of the tissue. We assessed the effect of an 808nm diode laser on the proliferation of human chondrocytes. Methods: This study was conducted on human chondrocytes in vitro. The cells were divided into 5 cases and one control group. The cells were irradiated by low-level laser 808 nm, with energy levels of 1, 2, 3 J/cm2 (0.2 W, for 5, 10, and 15 seconds), 4 J/cm2 (0.3 W,13 s), and 5 J/cm2 (0.4 W,12 s). The culture was incubated for 24 hours. The MTT assay was performed to determine the cell viability. After 72 hours of incubation, the procedure was reperformed to assess the effect of incubation duration. The cell viability in terms of incubation duration and irradiation parameters were investigated by a two-way ANOVA test. Pairwise comparisons were performed using the Bonferroni test. Results: In the 72-hour incubation group, cell viability in the group that received 5 J/cm2 energy was significantly lower than that in the groups receiving 1 J/cm2, 2 J/cm2 and 4 J/cm2 irradiation. The variables of time (P=0.001) and energy level (P=0.024) had significant effects on the cell viability of the samples. In the 24-hour incubation groups, no significant difference in cell viability was observed. Conclusion: The diode 808 nm Low-level laser irradiation (LLLI) at doses of 5 J/cm2 and less did not show a significant increase in the proliferation of chondrocytes (regardless of incubation time). However, the best survival rate of chondrocytes was observed in the group of 4 J/cm2 with 72-hour incubation.

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.

Blue light-driven cell cycle arrest in thyroid cancer via Retinal-OPN3 complex

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy, with a rising incidence. Traditional treatments, such as thyroidectomy and radiotherapy, often lead to significant side effects, including impaired thyroid function. Therefore, there is an urgent need for non-invasive therapeutic approaches. This study aims to explore the potential of photobiomodulation therapy (PBMT), a non-invasive treatment using specific wavelengths of light, in the management of PTC.

METHODS

We investigated the effects of blue light PBMT on PTC cells, focusing on the Retinal-OPSIN 3 (OPN3) complex's role in mediating cellular responses. Blue light exposure was applied to PTC cells, and subsequent changes in cellular proliferation, cell cycle progression, and protein expression were analyzed. Statistical tests, including one-way ANOVA and t-tests, were used to evaluate the significance of the findings.

RESULTS

Blue light exposure led to the dissociation of 11-cis-retinal from OPN3, resulting in the accumulation of all-trans retinal. This accumulation disrupted cellular proliferation pathways and induced G0/G1 cell cycle arrest in PTC cells. The Retinal-OPN3 complex was found to be a key mediator in these processes, demonstrating that thyroid cells can respond to specific light wavelengths and utilize their photoreceptive potential for therapeutic purposes.

CONCLUSIONS

Our findings suggest that PBMT, through the modulation of the Retinal-OPN3 complex, offers a promising non-invasive approach for treating PTC. This study highlights the therapeutic potential of light signal transduction in non-ocular tissues and opens new avenues for non-invasive cancer therapies.

Comparative efficacy of low-level laser therapy (LLLT) to TENS and therapeutic ultrasound in management of TMDs: a systematic review & meta-analysis

OBJECTIVE

To assess the reduction in pain, muscle tenderness, joint clicking, and improvement in mouth opening (MO) after low-level laser therapy (LLLT) compared to transcutaneous electrical nerve stimulation (TENS) and therapeutic ultrasound (US) among temporomandibular joint disorder (TMD) patients.

METHODS

A systematic search of online sources of electronic databases was undertaken. The quality of the study was assessed using the Cochrane risk of bias assessment tool for randomized controlled trials (RCTs).

RESULTS

Twelve RCTs were included in the systematic review, and 9 were included in the meta-analysis. For reduction in pain between LLLT and TENS, LLLT was found to be better than TENS, at 95% CI. LLLT was also proven to be better in reducing pain than therapeutic US, at 81% CI.

CONCLUSION

This systematic review and meta-analysis compared the effectiveness of LLLT, TENS, and therapeutic US in TMD. LLLT provided relatively more effective pain relief and improvement in MO.

Histological Improvement and Cytokine Levels Reduction in Patients with Oral Lichen Planus after Photobiomodulation Therapy

Background: Oral lichen planus (OLP) is a mucocutaneous disease associated with the formation of symptomatic lesions in the mouth that are often refractory to treatment. An as-yet-unknown antigen triggers an inflammatory reaction in which various immune and non-immune cells release multiple cytokines that contribute to disease progression. The ability of photobiomodulation (PBM) to reduce the symptoms and signs of the disease has been shown, but little is known about its molecular and cellular effects. The aim of this study was to evaluate changes in pro-inflammatory cytokine levels and in histological findings in OLP patients treated with photobiomodulation therapy. Methods: Twenty OLP patients underwent PBM with diode laser (810 nm), (0.50 W, 30 s, 1.2 J/cm2), 3 times weekly for a month. Pain level and clinical scores of lesions were recorded before and after therapy. Salivary levels of IL-1β, IL-6, and TNF-α in OLP patients were measured before and after PBM and compared with those of 10 healthy controls. Biopsies were taken at the beginning and end of treatment to assess pathomorphological changes. Results: PBM significantly reduced the level of pain and clinical scores of the lesions. Salivary levels of IL-1β, IL-6, and TNF-α in OLP patients were significantly higher compared to those in healthy controls and decreased after therapy. 60% of the post-treatment OLP biopsies demonstrated histological improvement, characterized by inflammatory infiltrate reduction (50%), epithelial hyperplasia reduction (30%), epithelial thickening (15%), or epidermal-dermal attachment repair (5%). Conclusion: The effectiveness of PBM therapy in OLP patients was confirmed at the clinical, molecular, and histomorphological levels.

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.

Selective induction of senescence in cancer cells through near-infrared light treatment via mitochondrial modulation

Photobiomodulation, utilising non-ionising light in the visible and near-infrared (NIR) spectrum, has been suggested as a potential method for enhancing tissue repair, reducing inflammation and possibly mitigating cancer-therapy-associated side effects. NIR light is suggested to be absorbed intracellularly, mainly by chromophores within the mitochondria. This study examines the impact of 734 nm NIR light on cellular senescence. Cancer (MCF7 and A549) and non-cancer (MCF10A and IMR-90) cell populations were subjected to 63 mJ/cm2 NIR-light exposure for 6 days. Senescence levels were quantified by measuring active senescence-associated beta-galactosidase. Exposure to NIR light significantly increases senescence levels in cancer (10.0%-203.2%) but not in non-cancer cells (p > 0.05). Changes in senescence were associated with significant modulation of mitochondrial homeostasis, including increased levels of reactive oxygen species (p < 0.05) and mitochondrial membrane potential (p < 0.05) post-NIR-light treatment. These results suggest that NIR light modulates cellular chemistry, arresting the proliferation of cancer cells via senescence induction while sparing non-cancer cells.

Effectiveness of low-level laser therapy in reducing pain score and healing time of recurrent aphthous stomatitis: a systematic review and meta-analysis

BACKGROUND

Recurrent aphthous stomatitis (RAS) is a common chronic inflammatory oral disease that negatively impacts the quality of life. Current therapies aim to reduce pain and healing process yet challenges such as rapid loss due to salivary flushing in topical drugs and adverse effects due to prolonged use of systemic medications require further notice. Low-level laser therapy is reported with immediate pain relief and faster healing thus preserving the potential for optimal treatment modalities. This review critically analyses and summarizes the effectiveness of LLLT in reducing pain scores and healing time of RAS.

METHODS

A systematic search was conducted in ScienceDirect, PubMed, and Scopus using keywords of low-level laser therapy, photo-biomodulation therapy, and recurrent aphthous stomatitis. RCTs between 1967 to June 2022, presenting characteristics of the laser and reporting pain score and/or healing time of RAS after irradiation were included. Animal studies and recurrent aphthous ulcers with a history of systemic conditions were excluded. Studies were critically appraised using the RoB 2 tool. A meta-analysis was performed using inverse variance random effects.

RESULTS

Fourteen trials with a total of 664 patients were included. Reduced pain was reported in 13 studies, while shortened healing time was presented in 4. The pooling of two studies after CO2 irradiation demonstrated faster healing time compared to placebo (MD - 3.72; 95% CI - 4.18, - 3.25).

CONCLUSION

Pain score and healing time of RAS were reduced after irradiation with LLLT. RoB resulted in "some concerns" urging well-designed RCTs with larger samples to further assess each laser application for comparison.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022355737.

Enhancement of skin rejuvenation and hair growth through novel near-infrared light emitting diode (nNIR) lighting: in vitro and in vivo study

The study aimed to explore the impact of a novel near-infrared LED (nNIR) with an extended spectrum on skin enhancement and hair growth. Various LED sources, including White and nNIRs, were compared across multiple parameters: cytotoxicity, adenosine triphosphate (ATP) synthesis, reactive oxygen species (ROS) reduction, skin thickness, collagen synthesis, collagenase expression, and hair follicle growth. Experiments were conducted on human skin cells and animal models. Cytotoxicity, ATP synthesis, and ROS reduction were evaluated in human skin cells exposed to nNIRs and Whites. LED irradiation effects were also studied on a UV-induced photoaging mouse model, analyzing skin thickness, collagen synthesis, and collagenase expression. Hair growth promotion was examined as well. Results revealed both White and nNIR were non-cytotoxic to human skin cells. nNIR enhanced ATP and collagen synthesis while reducing ROS levels, outperforming the commonly used 2chip LEDs. In the UV-induced photoaging mouse model, nNIR irradiation led to reduced skin thickness, increased collagen synthesis, and lowered collagenase expression. Additionally, nNIR irradiation stimulated hair growth, augmented skin thickness, and increased hair follicle count. In conclusion, the study highlighted positive effects of White and nNIR irradiation on skin and hair growth. However, nNIR exhibited superior outcomes compared to White. Its advancements in ATP content, collagen synthesis, collagenase inhibition, and hair growth promotion imply increased ATP synthesis activity. These findings underscore nNIR therapy's potential as an innovative and effective approach for enhancing skin and promoting hair growth.

A novel investigational preclinical model to assess fluence rate for dental oral craniofacial tissues

OBJECTIVE

Photodynamic Therapy (PDT) and Photobiomodulation (PBM) are recognized for their potential in treating head and neck conditions. The heterogeneity of human tissue optical properties presents a challenge for effective dosimetry. The porcine mandible cadaver serves as an excellent model and has several similarities to human tissues of the dental oral craniofacial complex. This study aims to validate a novel modeling system that will help refine PDT and PBM dosimetry for the head and neck region.

METHODS AND MATERIALS

Light transmission was analyzed through several tissue combinations at distances of 2 mm to 10 mm. Maximum light fluence rates (mW/cm2) were compared across tissue types to reveal the effects of tissue heterogeneity.

RESULTS

The study revealed that light fluence is affected by tissue composition, with dentin/enamel showing reduced transmission and soft tissue regions exhibiting elevated values. The porcine model has proven to be efficient in mimicking human tissue responses to light, enabling the potential to optimize future protocols.

CONCLUSION

The porcine mandible cadaver is a novel model to understand the complex interactions between light and tissue. This study provides a foundation for future investigations into dosimetry optimization for PDT and PBM.

Molecular signaling and mechanisms of low-level laser-induced gene expression in cells involved in orthodontic tooth movement

BACKGROUND

The study aimed to observe molecular signaling, including reactive oxygen species (ROS) and mitochondrial membrane potential (ΔΨm), to evaluate the alteration of gene expression by low-level laser therapy (LLLT) and the correlation between its mechanisms and the NF-kB pathway in cells involved in orthodontic tooth movement.

METHODS

Osteoblast-like cells (MG63), immortalized periodontal ligament cells (iPDL), and M1 macrophage-like cells were irradiated by 980-nm LLLT with energy densities of 1 and 10 J/cm2 ΔΨm and intracellular ROS were monitored using fluorescent probes. The changes of mRNA expression were assessed using reverse transcription polymerase chain reaction (RT-PCR). NF-kB inhibitor, ROS scavenger, and ΔΨm suppressor were used to analyze signals associated with the regulation of gene expression. Finally, Western blot analysis was performed to confirm NF-kB signaling after LLLT.

RESULTS

We found the increases of ΔΨm and ROS in all three cell types after LLLT, but no significant difference was observed between 1 and 10 J/cm2 LLLT. Regarding gene expression, some target genes were upregulated in MG63 6 h, 12 h, and 1 day after LLLT and in iPDL cells 12 h and 1 day after LLLT. However, no changes occurred in M1 cells. The inhibitor that significantly reduced most changes in gene expression was NF-kB inhibitor. Western blot analysis showed the increase in p-IkBα level after LLLT in iPDL and MG63, but not in M1.

CONCLUSION

The 980-nm LLLT increased ΔΨm and ROS production in all three cell types. However, changes in gene regulation were found only in MG63 and iPDL cells, which related to the NF-kB pathway.

Effect of various photobiomodulation regimens on breast cancer-related lymphedema: A systematic review and meta-analysis

Breast cancer-related lymphedema (BCRL) is common among patients who have completed their cancer treatment. Although low-level laser therapy (LLLT) has been explored as a treatment option for BCRL, we could not find a regimen that is more effective than others. This meta-analysis aimed to organize existing research and determine the optimal combination of LLLT parameters for BCRL treatment. Studies were collected from four online databases: Embase, Ovid Medline, Cochrane, and Cinahl. The collected studies were reviewed by two of the authors. We focused on the aspects of the treatment area, treatment regimen, and total treatment sessions across the included studies. The comparisons between LLLT and non-LLLT were performed through a meta-analysis. Post-treatment QOL was significantly better in the axillary group. The group treated "three times/week with a laser density of 1.5-2 J/cm2" had significantly better outcomes in terms of swelling reduction, both immediately post-treatment and at 1-3 months follow-ups. The group with > 15 treatment sessions had significantly better post-treatment outcomes regarding reduced swelling and improved grip strength. According to these results, LLLT can relieve the symptoms of BCRL by reducing limb swelling and improving QOL. Further exploration found that a treatment approach targeting the axilla, combined with an increased treatment frequency, appropriate laser density, and extended treatment course, yielded better outcomes. However, further rigorous, large-scale studies, including long-term follow-up, are needed to substantiate this regimen.

Efficacy of Low-Level Laser Therapy for Oral Mucositis in Hematologic Patients Undergoing Transplantation: A Single-Arm Prospective Study

Oral mucositis significantly affects the quality of life in hematologic cancer patients undergoing hematopoietic stem cell transplantation. Despite global evidence supporting the efficacy of low-level laser therapy (LLLT) for mucositis prevention, its clinical adoption in Japan is limited. This study aimed to fill this gap by evaluating the safety and efficacy of LLLT in a Japanese patient population. In a single-group, non-blinded, exploratory trial, we compared 21 LLLT-treated patients against a historical control of 96 patients. The primary endpoint was the incidence of Grade ≥ 2 mucositis, based on NCI-CTCAE ver. 4.0. The LLLT group showed a significantly lower incidence of Grade ≥ 2 mucositis (23.8%) compared to the control group (64.6%) (p = 0.0006). Furthermore, Grade ≥ 2 mucositis correlated with increased oral dryness and longer hospital stays. Our study confirms the efficacy of LLLT in reducing the onset of severe oral mucositis among Japanese hematologic cancer patients, advocating for its clinical introduction as a preventive measure in Japan.

Photobiological modulation of hepatoma cell lines and hepatitis B subviral particles secretion in response to 650 nm low level laser treatment

BACKGROUND

Chronic hepatitis B virus (HBV) infection is a serious global health concern, with an increased incidence and risk of developing cirrhosis and hepatocellular carcinoma (HCC). Patients chronically infected with HBV are likely to experience chronic oxidative stress, leading to mitochondrial dysfunction. Photobiomodulation is induced by the absorption of low-level laser therapy (LLLT) with a red or infrared laser by cytochrome C oxidase enzyme, resulting in mitochondrial photoactivation. Although it is widely used in clinical practice, the use of LLL as adjuvant therapy for persistent HBV infection is uncommon. This study aimed to investigate the effect of LLLT dosage from 2 J/cm2 to 10 J/cm2 of red diode laser (650 nm) on both hepatoma cell lines (HepG2.2.15 [integrated HBV genome stable cell model] and non-integrated HepG2), with a subsequent impact on HBVsvp production.

METHODS

The present study evaluated the effects of different fluences of low-level laser therapy (LLLT) irradiation on various aspects of hepatoma cell behavior, including morphology, viability, ultrastructure, and its impact on HBVsvp synthesis.

RESULTS

In response to LLLT irradiation, we observed a considerable reduction in viability, proliferation, and HBVsvp production in both hepatoma cell lines HepG2.2.15 and HepG2. Ultrastructural modification of mitochondria and nuclear membranes: This effect was dose, cell type, and time-dependent.

CONCLUSIONS

The use of LLLT may be a promising therapy for HCC and HBV patients by reducing cell proliferation, HBVsvp production, and altering mitochondrial and nuclear structure involved in cellular death inducers. Further research is required to explore its clinical application.

Interaction of the AKT and β-catenin signalling pathways and the influence of photobiomodulation on cellular signalling proteins in diabetic wound healing

The induction of a cells destiny is a tightly controlled process that is regulated through communication between the matrix and cell signalling proteins. Cell signalling activates distinctive subsections of target genes, and different signalling pathways may be used repeatedly in different settings. A range of different signalling pathways are activated during the wound healing process, and dysregulated cellular signalling may lead to reduced cell function and the development of chronic wounds. Diabetic wounds are chronic and are characterised by the inability of skin cells to act in response to reparative inducements. Serine/threonine kinase, protein kinase B or AKT (PKB/AKT), is a central connection in cell signalling induced by growth factors, cytokines and other cellular inducements, and is one of the critical pathways that regulate cellular proliferation, survival, and quiescence. AKT interacts with a variety of other pathway proteins including glycogen synthase kinase 3 beta (GSK3β) and β-catenin. Novel methodologies based on comprehensive knowledge of activated signalling pathways and their interaction during normal or chronic wound healing can facilitate quicker and efficient diabetic wound healing. In this review, we focus on interaction of the AKT and β-catenin signalling pathways and the influence of photobiomodulation on cellular signalling proteins in diabetic wound healing.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: a systematic review and meta-analysis of split-mouth randomised clinical trials

Although several studies have evaluated the effect of low-level laser therapy (LLLT) on orthodontic movement acceleration, results are still inconsistent. Such inconsistencies may be attributed to the differences in the LLLT application protocols, especially in terms of wavelength ranges. Objective: (i) to assess the clinical effects of LLLT on the acceleration of orthodontic movement and (ii) to establish the most effective LLLT wavelength to accelerate tooth movement during orthodontic treatments. MEDLINE (PubMed), Scopus, ScienceDirect, and LILACS were searched from inception to October 2022. Inclusion criteria: Split-mouth randomised clinical trials (RCTs) on systemically healthy patients reporting the effect of LLLT in accelerating orthodontic movements, specifically retraction of canines. The risk of bias was assessed using RoB-2. A random effect model was applied. Nineteen RCTs met the inclusion criteria for qualitative synthesis, and eighteen RCTs were included in the quantitative synthesis. Seventeen studies were rated as at some concerns of bias and two studies were classified as having a low risk of bias. In general terms, this systematic review and meta-analysis presents a moderate risk of bias. Findings of this systematic review and meta-analysis point to a tendency for faster orthodontic dental movement in the groups receiving LLLT treatment during the first (OR of 0.28 95% CI (0.07 to 0.48)), second (OR of 0.52 95% CI (0.31 to 0.73)), and third (OR of 0.41 95% CI (0.03 to 0.79)) month follow-up. Wavelengths ≤ 810 nm and energy density values ≤ 5.3 J/cm2 were associated with faster orthodontic tooth movement.

Effects of photobiomodulation by low-power lasers and LEDs on the viability, migration, and invasion of breast cancer cells

Among the malignant tumors, breast cancer is the most commonly diagnosed worldwide, being the most prevalent in women. Photobiomodulation has been used for wound healing, swelling and pain reduction, and muscle repair. The application of photobiomodulation in cancer patients has been controversial. Therefore, a better understanding of radiation-induced effects involved in photobiomodulation on cancer cells is needed. Thus, this study aimed to investigate the effects of exposure to low-power lasers and LEDs on cell viability, migration, and invasion in human breast cancer cells. MCF-7 and MDA-MB-231 cells were irradiated with a low-power red laser (23, 46, and 69 J/cm2, 0.77 W/cm2) and blue LED (160, 321, and 482 J/cm2, 5.35 W/cm2), alone or in combination. Cell viability was assessed using the WST-1 assay, cell migration was evaluated using the wound healing assay, and cell invasion was performed using the Matrigel transwell assay. Viability and migration were not altered in MCF-7 and MDA-MB-231 cultures after exposure to low-power red laser and blue LED. However, there was a decrease in cell invasion from the cultures of the two cell lines evaluated. The results suggest that photobiomodulation induced by low-power red laser and blue LED does not alter cell viability and migration but decreases cell invasion in human breast cancer cells.

Photobiomodulation at molecular, cellular, and systemic levels

Since the reporting of Endre Mester's results, researchers have investigated the biological effects induced by non-ionizing radiation emitted from low-power lasers. Recently, owing to the use of light-emitting diodes (LEDs), the term photobiomodulation (PBM) has been used. However, the molecular, cellular, and systemic effects involved in PBM are still under investigation, and a better understanding of these effects could improve clinical safety and efficacy. Our aim was to review the molecular, cellular, and systemic effects involved in PBM to elucidate the levels of biological complexity. PBM occurs as a consequence of photon-photoacceptor interactions, which lead to the production of trigger molecules capable of inducing signaling, effector molecules, and transcription factors, which feature it at the molecular level. These molecules and factors are responsible for cellular effects, such as cell proliferation, migration, differentiation, and apoptosis, which feature PBM at the cellular level. Finally, molecular and cellular effects are responsible for systemic effects, such as modulation of the inflammatory process, promotion of tissue repair and wound healing, reduction of edema and pain, and improvement of muscle performance, which features PBM at the systemic level.

Suppressing cancer by damaging cancer cell DNA using LED irradiation

BACKGROUND

High-energy irradiation eliminates cancer cells by destroying their genetic components. However, there are several side effects from doing this, such as fatigue, dermatitis, and hair loss, which remain obstacles to this treatment. Here, we propose a moderate method that uses low-energy white light from a light-emitting diode (LED) to selectively inhibit cancer cell proliferation without affecting normal cells.

METHODS

The association between LED irradiation and cancer cell growth arrest was evaluated based on cell proliferation, viability, and apoptotic activity. Immunofluorescence, polymerase chain reaction, and western blotting were performed in vitro and in vivo to identify the metabolism related to the inhibition of HeLa cell proliferation.

RESULTS

LED irradiation aggravated the defective p53 signaling pathway and induced cell growth arrest in cancer cells. Consequently, cancer cell apoptosis was induced by the increased DNA damage. Additionally, LED irradiation inhibited the proliferation of cancer cells by suppressing the MAPK pathway. Furthermore, the suppression of cancer growth by the regulation of p53 and MAPK was observed in cancer-bearing mice irradiated with LED.

CONCLUSIONS

Our findings suggest that LED irradiation can suppress cancer cell activity and may contribute to preventing the proliferation of cancer cells after medical surgery without causing side effects.

Laser therapy versus pulsed electromagnetic field therapy as treatment modalities for early knee osteoarthritis: a randomized controlled trial

BACKGROUND

This randomized controlled trial aimed to compare the effects of pulsed electromagnetic field therapy (PEMFT) and low-level laser therapy (LLLT) on pain and physical function of participants with knee osteoarthritis (KOA).

METHODS

According to the Kellgren-Lawrence classification, participants with grade 2-3 KOA were randomized to receive PEMFT or LLLT for six sessions lasting 15 min/session over a 3-week period. Pain at rest and when walking, standing from a sitting position, and climbing the stairs was assessed using the visual analog scale. Functional level was measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), timed up-and-go test (TUG), and 10-m walk (10 MW) test. Measurements were obtained before and after the interventions. Significance was determined at p ≤ 0.05.

RESULTS

Forty participants were included in the study. Pain and physical function improved significantly (p < 0.0001) in both groups. PEMFT was significantly more effective in reducing pain at rest, when standing from a sitting position, and when climbing the stairs, and in improving both WOMAC scores and TUG results (p ≤ 0.0003). The improvements in pain during the activities and the WOMAC scores reached the minimal clinically important difference. No adverse events occurred.

CONCLUSION

Six sessions of PEMFT and LLLT had immediate positive effects on pain and physical function in individuals with low-grade KOA, with PEMFT resulting in significantly better results.

TRIAL REGISTRATION

ISRCTN registry trial ID: ISRCTN17001174.

Effect of femtosecond laser interaction with human fibroblasts: a preliminary study

In in vitro methods and cell culture models, femtosecond (fs) laser interaction has been employed to assess its effect on the proliferation and morphology of human skin fibroblasts. We cultured a primary human skin fibroblast cell line on a glass plate, passages 17-23. The cells were irradiated with a 90-fs laser at a wavelength of 800 nm and a repetition rate of 82 MHz. The target received an average power of 320 mW for 5, 20, and 100 s, corresponding to the radiation exposures of 22.6, 90.6, and 452.9 J/cm2, respectively. Using a laser scanning microscopy technique, the photon densities were measured to be 6.4 × 1018, 2.6 × 1019, and 1.3 × 1020 photons/cm2 in a spot area of 0.07 cm2; the recorded spectra were obtained from the laser interaction after 0.00, 1.00, 25.00, and 45.00 h. The cell count and morphological changes showed that the cultured cells were affected by laser irradiation under photon stress; some fibroblasts were killed, while others were injured and survived. We discovered evidence of the formation of several coenzyme compounds, such as flavin (500-600 nm), lipopigments (600-750 nm), and porphyrin (500-700 nm). This study is motivated by the future development of a novel, ultra-short fs laser system and the need to develop a basic in vitro understanding of photon-human cell interaction. The cell proliferation indicated that cells are partly killed or wounded. The exposure of fibroblasts to fs laser fluence up to 450 J/cm2 accelerates cell growth of the viable residual cell.

Physical Rehabilitation in Zoological Companion Animals

Animal physical rehabilitation is one of the fast-growing fields in veterinary medicine in recent years. It has become increasingly common in small animal practice and will continue to emerge as an essential aspect of veterinary medicine that plays a vital role in the care of animals with physical impairments or disabilities from surgery, injuries, or diseases.1 This is true now more than ever because of the increasing advances in lifesaving treatments, the increased lifespan of companion animals, and the growth of chronic conditions, of which many are associated with movement disorders. The American Association of Rehabilitation Veterinarians (AARV) defines APR as "the diagnosis and management of patients with painful or functionally limiting conditions, particularly those with injury or illness related to the neurologic and musculoskeletal systems." Rehabilitation not only focuses on recovery after surgical procedures but also on improving the function and quality of life in animals suffering from debilitating diseases such as arthritis or neurologic disorders. The overall goal of APR is to decrease pain, reduce edema, promote tissue healing, restore gait and mobility to its prior activity level, regain strength, prevent further injury, and promote optimal quality of life. Typically, a multimodal approach with pharmaceutical and nonpharmaceutical interventions is used by APR therapists to manage patients during their recovery. The purpose of this article aims to provide knowledge and guidance on physical rehabilitation to help veterinarians in the proper return of their patients with ZCA safely after injury and/or surgery.

Efficacy of Low-Level Laser Therapy in a Rabbit Model of Rhinosinusitis

Little is known about alternative treatment options for rhinosinusitis (RS). We aimed to evaluate the efficacy of low-level laser therapy (LLLT) for RS in experimentally induced rabbit models of RS. A total of 18 rabbits were divided into four groups: a negative control group (n = 3), an RS group without treatment (n = 5, positive control group), an RS group with natural recovery (n = 5, natural recovery group), and an RS group with laser irradiation (n = 5, laser-treated group). Computed tomography and histopathological staining were performed for each group. mRNA and protein expression levels of local cytokines (IFN-γ, IL-17, and IL-5) were also measured. Tissue inflammation revealed a significant improvement in the laser-treated group compared with the RS and natural recovery groups (p < 0.01). In addition, sinus opacification in the CT scans and cytokine expression was reduced in the laser-treated group, though without statistical significance. LLLT could be an effective option for the management of RS concerning radiological, histological, and molecular parameters.

The distinguishing electrical properties of cancer cells

In recent decades, medical research has been primarily focused on the inherited aspect of cancers, despite the reality that only 5-10% of tumours discovered are derived from genetic causes. Cancer is a broad term, and therefore it is inaccurate to address it as a purely genetic disease. Understanding cancer cells' behaviour is the first step in countering them. Behind the scenes, there is a complicated network of environmental factors, DNA errors, metabolic shifts, and electrostatic alterations that build over time and lead to the illness's development. This latter aspect has been analyzed in previous studies, but how the different electrical changes integrate and affect each other is rarely examined. Every cell in the human body possesses electrical properties that are essential for proper behaviour both within and outside of the cell itself. It is not yet clear whether these changes correlate with cell mutation in cancer cells, or only with their subsequent development. Either way, these aspects merit further investigation, especially with regards to their causes and consequences. Trying to block changes at various levels of occurrence or assisting in their prevention could be the key to stopping cells from becoming cancerous. Therefore, a comprehensive understanding of the current knowledge regarding the electrical landscape of cells is much needed. We review four essential electrical characteristics of cells, providing a deep understanding of the electrostatic changes in cancer cells compared to their normal counterparts. In particular, we provide an overview of intracellular and extracellular pH modifications, differences in ionic concentrations in the cytoplasm, transmembrane potential variations, and changes within mitochondria. New therapies targeting or exploiting the electrical properties of cells are developed and tested every year, such as pH-dependent carriers and tumour-treating fields. A brief section regarding the state-of-the-art of these therapies can be found at the end of this review. Finally, we highlight how these alterations integrate and potentially yield indications of cells' malignancy or metastatic index.

Progress of phototherapy for osteosarcoma and application prospect of blue light photobiomodulation therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor that mainly affects the pediatric and adolescent population; limb salvage treatment has become one of the most concerned and expected outcomes of OS patients recently. Phototherapy (PT), as a novel, non-invasive, and efficient antitumor therapeutic approach including photodynamic therapy (PDT), photothermal therapy (PTT), and photobiomodulation therapy (PBMT), has been widely applied in superficial skin tumor research and clinical treatment. OS is the typical deep tumor, and its phototherapy research faces great limitations and challenges. Surprisingly, pulse mode LED light can effectively improve tissue penetration and reduce skin damage caused by high light intensity and has great application potential in deep tumor research. In this review, we discussed the research progress and related molecular mechanisms of phototherapy in the treatment of OS, mainly summarized the status quo of blue light PBMT in the scientific research and clinical applications of tumor treatment, and outlooked the application prospect of pulsed blue LED light in the treatment of OS, so as to further improve clinical survival rate and prognosis of OS treatment and explore corresponding cellular mechanisms.

Iron Oxide-Au Magneto-Plasmonic Heterostructures: Advances in Their Eco-Friendly Synthesis

In recent years, nanotechnologies have attracted considerable interest, especially in the biomedical field. Among the most investigated particles, magnetic based on iron oxides and Au nanoparticles gained huge interest for their magnetic and plasmonic properties, respectively. These nanoparticles are usually produced starting from processes and reagents that can be the cause of potential human health and environmental concerns. For this reason, there is a need to develop simple, green, low-cost, and non-toxic synthesis methods and reagents. This review aims at providing an overview of the most recently developed processes to produce iron oxide magnetic nanoparticles, Au nanoparticles, and their magneto-plasmonic heterostructures using eco-friendly approaches, focusing the attention on the microorganisms and plant-assisted syntheses and showing the first results of the development of magneto-plasmonic heterostructures.

Use of Photobiomodulation Combined with Fibrin Sealant and Bone Substitute Improving the Bone Repair of Critical Defects

In this preclinical protocol, an adjunct method is used in an attempt to overcome the limitations of conventional therapeutic approaches applied to bone repair of large bone defects filled with scaffolds. Thus, we evaluate the effects of photobiomodulation therapy (PBMT) on the bone repair process on defects filled with demineralized bovine bone (B) and fibrin sealant (T). The groups were BC (blood clot), BT (B + T), BCP (BC + PBMT), and BTP (B + T + PBMT). Microtomographically, BC and BCP presented a hypodense cavity with hyperdense regions adjacent to the border of the wound, with a slight increase at 42 days. BT and BTP presented discrete hyperdensing areas at the border and around the B particles. Quantitatively, BCP and BTP (16.96 ± 4.38; 17.37 ± 4.38) showed higher mean bone density volume in relation to BC and BT (14.42 ± 3.66; 13.44 ± 3.88). Histologically, BC and BCP presented deposition of immature bone at the periphery and at 42 days new bone tissue became lamellar with organized total collagen fibers. BT and BTP showed inflammatory infiltrate along the particles, but at 42 days, it was resolved, mainly in BTP. In the birefringence analysis, BT and BTP, the percentage of red birefringence increased (9.14% to 20.98% and 7.21% to 27.57%, respectively), but green birefringence was similar in relation to 14 days (3.3% to 3.5% and 3.5% to 4.2%, respectively). The number of osteocytes in the neoformed bone matrix proportionally reduced in all evaluated groups. Immunostaining of bone morphogenetic protein (BMP—2/4), osteocalcin (OCN), and vascular endothelial growth factor (VEGF) were higher in BCP and BTP when compared to the BC and BT groups (p < 0.05). An increased number of TRAP positive cells (tartrate resistant acid phosphatase) was observed in BT and BTP. We conclude that PBMT positively influenced the repair of bone defects filled with B and T.

Viral inactivation by light

Nowadays, viral infections are one of the greatest challenges for medical sciences and human society. While antiviral compounds and chemical inactivation remain inadequate, physical approaches based on irradiation provide new potentials for prevention and treatment of viral infections, without the risk of drug resistance and other unwanted side effects. Light across the electromagnetic spectrum can inactivate the virions using ionizing and non-ionizing radiations. This review highlights the anti-viral utility of radiant methods from the aspects of ionizing radiation, including high energy ultraviolet, gamma ray, X-ray, and neutron, and non-ionizing photo-inactivation, including lasers and blue light.

Stimulatory effects of wavelength-dependent photobiomodulation on proliferation and angiogenesis of colorectal cancer

In recent decades, the laser treatment of cancer has been introduced as a promising treatment option. Because of the maldistribution of optical energy and an ambiguous boundary between the normal and tumor tissues, laser irradiation can stimulate residual cancer cells, leading to a cancer regrowth. As photobiomodulation (PBM) is involved in an extensive range of cellular responses, profound comprehension of photo-stimulated mechanisms against the cancer cells is required to establish a safety margin for PBM. Therefore, we aimed to identify the stimulant effects of PBM at various wavelengths against the tumor cells to establish a safety margin for the laser treatment. CT26 murine colon cancer cells were exposed to either 405 (BL), 635 (VIS), or 808 (NIR) nm laser lights at the fluences of 0, 10, 30, and 50 J/cm². In addition, CT26 tumor-bearing mice were irradiated with BL, VIS, or NIR at a fluence of 30 J/cm². Both the proliferation and angiogenesis potential of the CT26 cells and tumors were evaluated using the MTT assay, western blot, and immunohistochemistry (IHC) staining analyses. Although cell viability was not statistically significant, BL significantly induced p-ERK upregulation in the CT26 cells, indicating that PBM with BL can stimulate proliferation. In vivo tests showed that the NIR group exhibited the maximum relative tumor volume, and BL yielded a slight increase compared to the control. In the IHC staining and western blot analyses, both BL and NIR increased the expression of EGFR, VEGF, MMP-9, and HIF-1α, which are related to the proliferation and angiogenesis-related factors. Further investigations will be pursued to clarify the molecular pathways that depend on the cancer cell types and laser wavelengths for the establishment of safety guidelines in clinical environments.

Changes in Cell Biology under the Influence of Low-Level Laser Therapy

Low-level laser therapy (LLLT) has become an important part of the therapeutic process in various diseases. However, despite the broad use of LLLT in everyday clinical practice, the full impact of LLLT on cell life processes has not been fully understood. This paper presents the current state of knowledge concerning the mechanisms of action of LLLT on cells. A better understanding of the molecular processes occurring within the cell after laser irradiation may result in introducing numerous novel clinical applications of LLLT and potentially increases the safety profile of this therapy.

Therapeutic Effect of a Low-Level Laser on Acute Pain and Post-operative Mouth Opening After Closed Reduction of Mandibular-Condylar Fracture

Introduction: The purpose of this study was to determine the therapeutic effect of low-level laser therapy (LLLT) on acute pain and the range of mouth opening after condylar closed reduction surgery. The use of low-level lasers, especially to reduce inflammation and pain, has received more attention in recent years. The results of many studies performed in this field are contradictory, and the effectiveness of low-level lasers in the treatment of patients is still uncertain. Methods: This study was performed as a randomized, double-blinded clinical trial on 40 patients with condylar closed reduction surgery. Patients were randomly assigned to two groups of 20 patients, including the placebo and intervention groups. In the intervention group, the patients received LLLT (100 mw, 2 J/cm², 20 S/point, 14 extraoral points, 7 days). The range of jaw movements after opening the intermaxillary-fixation was measured. Patients' pain was assessed using the visual analog scale (VAS). Data were analyzed using SPSS software version 21, the chi-square test, and repeated measures ANOVA. Results: There was no significant difference between the study groups in terms of the range of jaw motions. The mean VAS score was 56.85 (SD=3.817) in the intervention group and 60.95 (SD=4.861) in the placebo group, showing a statistically significant difference between the two groups at the end of the study (P=0.007) Conclusion: The results of this study indicated the effectiveness of low-level lasers in reducing acute pain in patients undergoing closed condylar surgery. Iranian Registry of Clinical Trials (IRCT20200520047519N1).

Near-Infrared Photobiomodulation of Living Cells, Tubulin, and Microtubules In Vitro

We report the results of experimental investigations involving photobiomodulation (PBM) of living cells, tubulin, and microtubules in buffer solutions exposed to near-infrared (NIR) light emitted from an 810 nm LED with a power density of 25 mW/cm² pulsed at a frequency of 10 Hz. In the first group of experiments, we measured changes in the alternating current (AC) ionic conductivity in the 50–100 kHz range of HeLa and U251 cancer cell lines as living cells exposed to PBM for 60 min, and an increased resistance compared to the control cells was observed. In the second group of experiments, we investigated the stability and polymerization of microtubules under exposure to PBM. The protein buffer solution used was a mixture of Britton-Robinson buffer (BRB aka PEM) and microtubule cushion buffer. Exposure of Taxol-stabilized microtubules (~2 μM tubulin) to the LED for 120 min resulted in gradual disassembly of microtubules observed in fluorescence microscopy images. These results were compared to controls where microtubules remained stable. In the third group of experiments, we performed turbidity measurements throughout the tubulin polymerization process to quantify the rate and amount of polymerization for PBM-exposed tubulin vs. unexposed tubulin samples, using tubulin resuspended to final concentrations of ~ 22.7 μM and ~ 45.5 μM in the same buffer solution as before. Compared to the unexposed control samples, absorbance measurement results demonstrated a slower rate and reduced overall amount of polymerization in the less concentrated tubulin samples exposed to PBM for 30 min with the parameters mentioned above. Paradoxically, the opposite effect was observed in the 45.5 μM tubulin samples, demonstrating a remarkable increase in the polymerization rates and total polymer mass achieved after exposure to PBM. These results on the effects of PBM on living cells, tubulin, and microtubules are novel, further validating the modulating effects of PBM and contributing to designing more effective PBM parameters. Finally, potential consequences for the use of PBM in the context of neurodegenerative diseases are discussed.

A Comparative Analysis of Photobiomodulation-Mediated Biological Effects of Single Versus Double Irradiation on Dental Pulp Stem Cells: An In Vitro Study

Objective: In recent years, fractionated irradiation protocols, rather than a simple plan of exposure, have been proposed as a more effective method in the field of tissue regeneration. Thus, this study aimed at a comparative analysis of single versus double irradiation of an 808-nm diode laser, in terms of dental pulp stem cells' (DPSCs) viability and proliferation in vitro. Methods: Subcultured DPSCs were either irradiated, or not (control group), with energy densities of 3, 7, and 12 J·cm^-2 in a single- or double-session manner (24 h apart). On 0, 12, 24, 48, and 72 h postirradiation, cell viability and proliferation were evaluated through Trypan Blue and alamarBlue assays, respectively. Results: During the first 48 h postirradiation, the highest rates of DPSC proliferation were assigned to double irradiation at 3 or single exposure to 7 J⋅cm^-2, with no cytotoxic effects on cell viability. Inversely, single irradiation at 12, or a double session of exposure to 7 or 12 J⋅cm^-2, led to a significant descent in the rates of proliferation and cell viability. Conclusions: Within the limitations of this study, evidence suggests a positive impact on the biological responses of DPSCs following double session of exposure to lower energy densities as well as a single irradiation at a higher energy dosage.

Regulatory Processes of the Canonical Wnt/β-Catenin Pathway and Photobiomodulation in Diabetic Wound Repair

Skin is a biological system composed of different types of cells within a firmly structured extracellular matrix and is exposed to various external and internal insults that can break its configuration. The restoration of skin's anatomic continuity and function following injury is a multifaceted, dynamic, well-coordinated process that is highly dependent on signalling pathways, including the canonical Wnt/β catenin pathway, all aimed at restoring the skin's protective barrier. Compromised and inappropriate tissue restoration processes are often the source of wound chronicity. Diabetic patients have a high risk of developing major impediments including wound contamination and limb amputation due to chronic, non-healing wounds. Photobiomodulation (PBM) involves the application of low-powered light at specific wavelengths to influence different biological activities that incite and quicken tissue restoration. PBM has been shown to modulate cellular behaviour through a variety of signal transduction pathways, including the Wnt/β catenin pathway; however, the role of Wnt/β catenin in chronic wound healing in response to PBM has not been fully defined. This review largely focuses on the role of key signalling pathways in human skin wound repair, specifically, the canonical Wnt/β-catenin pathway, and the effects of PBM on chronic wound healing.