Effect of LLLT on endothelial cells culture

Treatment with a red-laser-based wound therapy device exerts positive effects in models of delayed keratinocyte and fibroblast wound healing

BACKGROUND

Light therapy is widely used in medicine. Specifically, photobiomodulation has been shown to exert beneficial effects in wound healing disorders, which present a major challenge in health care. The study's aim was providing information on the effect of a novel, red-laser-based wound therapy device (WTD) on keratinocytes and fibroblasts during wound healing under optimal and non-optimal conditions.

METHODS

The scratch wound assay was employed as a wound healing model for mechanical damage with readjustment of specific cell milieus, explicitly chronic TH1 inflammation and TH2-dominant conditions. Furthermore, gene expression analysis of pro-inflammatory cytokines (IL1A, IL6, CXCL8), growth factors (TGFB1, PDGFC), transcription factors (NFKB1, TP53) and heat shock proteins (HSP90AA1, HSPA1A, HSPD1) as well as desmogleins (DSG1, DSG3) in keratinocytes and collagen (COL1A1, COL3A1) in fibroblasts was performed after WTD treatment.

RESULTS

It was shown that WTD treatment is biocompatible and supports scratch wound closure under non-optimal conditions. A distinct enhancement of desmoglein and collagen gene expression as well as induction of early growth factor gene expression was observed under chronic inflammatory conditions. Moreover, WTD increased HSPD1 transcript levels in keratinocytes and augmented collagen expression in fibroblasts during wound healing under TH2 conditions. WTD treatment also alleviated the inflammatory response in keratinocytes and induced early growth factor gene expression in fibroblasts under physiological conditions.

CONCLUSION

Positive effects described for wound treatment with WTD could be replicated in vitro and seem to be to be conferred by a direct influence on cellular processes taking place in keratinocytes and fibroblasts during wound healing.

Photobiomodulation and Vascularization in Conduit-Based Peripheral Nerve Repair: A Narrative Review

Background: Peripheral nerve injuries pose a significant clinical issue for patients, especially in the most severe cases wherein complete transection (neurotmesis) results in total loss of sensory/motor function. Nerve guidance conduits (NGCs) are a common treatment option that protects and guides regenerating axons during recovery. However, treatment outcomes remain limited and often fail to achieve full reinnervation, especially in critically sized defects (>3 cm) where a lack of vascularization leads to neural necrosis. Conclusions: A multitreatment approach is, therefore, necessary to improve the efficacy of NGCs. Stimulating angiogenesis within NGCs can help alleviate oxygen deficiency through rapid inosculation with the host vasculature, whereas photobiomodulation therapy (PBMT) has demonstrated beneficial therapeutic effects on regenerating nerve cells and neovascularization. In this review, we discuss the current trends of NGCs, vascularization, and PBMT as treatments for peripheral nerve neurotmesis and highlight the need for a combinatorial approach to improve functional and clinical outcomes.

Effects of NGF and Photobiomodulation Therapy on Crush Nerve Injury and Fracture Healing: A Stereological and Histopathological Study in an Animal Model

Study Design

A stereological and histopathological study in an animal model.

Objective

This study explores the effects of the nerve growth factor and photobiomodulation therapy on the damaged nerve tissue and fracture healing.

Methods

A total of 24 rabbits were divided into 4 groups: control group (n = 5), nerve growth factor (NGF) group (n = 7), photobiomodulation (PBMT) group (n = 6), and nerve growth factor and photobiomodulation therapy (NGF+PBMT) group (n = 6). The vertical fracture was performed between the mental foramen and the first premolar, and the mental nerve was crushed for 30 seconds with a standard serrated clamp with a force of approximately 50 N in all groups. The control group received an isotonic solution (.02 mL, .09% NaCl) to the operation site locally. The NGF group received 1 μg human NGF-β/.9% .2 mL NaCl solution for 7 days locally. The PBMT group received PBMT treatment (GaAlAs laser, 810 nm, .3 W, 18 J/cm2) every 48 hours for 14 sessions following the surgery. The NGF+PBMT group received both NGF and PBMT treatment as described above. After 28 days, the bone tissues and mental nerves from all groups were harvested and histologically and stereologically analyzed.

Results

According to the stereological results, the volume of the new vessel and the volume of the new bone were significantly higher in the PBMT group than in other groups (P < .001). According to the histopathological examinations, higher myelinated axons were observed in experimental groups than in the control group.

Conclusions

As a result, PBMT has beneficial effects on bone regeneration. Based on the light microscopic evaluation, more regenerated axon populations were observed in the NGF group than in the PBMT and PBMT + NGF groups in terms of myelinated axon content.

Enhanced periodontal tissue healing via vascular endothelial growth factor expression following low-level erbium-doped: yttrium, aluminum, and garnet laser irradiation: In vitro and in vivo studies

BACKGROUND

This study aimed to investigate the effects of low-level erbium-doped: yttrium, aluminum, and garnet (Er:YAG) laser irradiation on periodontal tissue healing and regeneration through angiogenesis in vivo and in vitro studies.

METHODS

Intrabony defects were surgically created in the bilateral maxilla molar of rats. The defects were treated by open flap debridement (OFD) with Er:YAG laser, including low-level laser irradiation (LLLI) to bone and blood clot surfaces, or conventional procedures. The mRNA expression of vascular endothelial growth factor (VEGF) in the surgical sites was quantified using real-time polymerase chain reaction. The decalcified specimens were prepared for histometric analysis. Also, LLLI was performed on human umbilical vein endothelial cells to evaluate the effects on angiogenesis. Cell proliferation, VEGF expression, and tube formation were assessed. In addition, capsazepine (CPZ), a selective inhibitor of transient receptor potential vanilloid 1 (TRPV1), treatment was performed before LLLI for the same assays.

RESULTS

OFD using Er:YAG laser did not generate thermal damage on bone or root surfaces. LLLI accelerated hemostasis by coagulation of the superficial layers of blood clots in the laser-treated group. Postoperative healing was sound in all animals in both groups. VEGF expression and bone formation were significantly increased in the laser-treated group compared to those in the conventional treatment group. In vitro, cell proliferation and VEGF expression were significantly increased in the LLLI group compared to the control group. Tube-formation assays showed that LLLI significantly promoted angiogenesis. CPZ treatment significantly suppressed VEGF expression and tube formation following LLLI.

CONCLUSIONS

This study suggests that Er:YAG laser irradiation may promote periodontal tissue healing by enhancing angiogenetic effect of endothelial cells via TRPV1.

Biomodulator of Diode Laser Irradiation on Odontoblast-Like Cells by Expression of Vascular Endothelial Growth Factor-A and Transforming Growth Factor-β1

OBJECTIVE

 This study aimed to prove that the effect of diode laser 650-nm irradiation to the expression of vascular endothelial growth factor (VEGF)-A and transforming growth factor (TGF)-β1 plays important roles in dental pulp-regulating cell proliferation, differentiation, and revascularization.

MATERIALS AND METHODS

 The research was performed by randomized posttest only control group design using Rattus norvegicus. A total of 48 samples were provided and divided into eight groups of 6 samples each with a random-sample allocation. Each group were prepared, and perforation of maxillary first molar were done. In control groups (groups 1-4), glass ionomer cement (GIC) was used to restore the teeth, while in laser groups (groups 5-8), the teeth were irradiated with diode laser 650 nm for 40 seconds before application of GIC. Half of the groups (groups 1, 2, 5, and 6) were necropsied in 7 days, and the rest (groups 3, 4, 7, and 8) were necropsied in 14 days. Immunohistochemistry (IHC) evaluation were implemented to check the expression of both VEGF-A and TGF-β1.

STATISTICAL ANALYSIS

 Both data of VEGF-A and TGF-β1 expression were analyzed using a one-way ANOVA (α = 0.05) with SPSS statistical software.

RESULTS

 The study showed that the diode laser 650-nm irradiation increased expression of VEGF-A and TGF-β1, and there was a significant difference between diode laser and control group on VEGF-A expression (p = 0.001) and TGF- β1 (p = 0.000) on days 7 and 14.

CONCLUSION

 Diode laser 650 nm with 40-second irradiation time shows increment from day 7 to day 14 reflecting increase in pulp healing by modulating VEGF-A and TGF-β1 expression since days 7 to 14.

Effects of photobiomodulation as an adjunctive treatment in chronic obstructive pulmonary disease: a narrative review

Chronic obstructive pulmonary disease (COPD) is a disease characterized by chronic airway inflammation and remodeling and lung parenchymal inflammation and destruction, which result in many pulmonary and extrapulmonary manifestations. The anti-inflammatory effect of photobiomodulation (PBM) has been reported in previous studies. This review was conducted to evaluate the direct effect of PBM on lung inflammation in COPD. The other effects of PBM on modulation of peripheral and respiratory muscle metabolism and angiogenesis in lung tissues were also discussed. The databases of PubMed, Cochrane Library, and Google Scholar were searched to find the relevant studies. Keywords included PBM and related terms, COPD-related signs, and lung inflammation. A total of 12 articles were selected and reviewed in this study. Based on the present review, PBM is helpful in reducing lung inflammation through decreasing the inflammatory cytokines and chemokines at multiple levels and increasing anti-inflammatory cytokines. In addition, PBM also improves both peripheral and respiratory muscle metabolism and promote angiogenesis. This review demonstrated that PBM is a promising adjunctive treatment modality for COPD management which merits further validation.

Low-Level Laser Therapy Induces Melanoma Tumor Growth by Promoting Angiogenesis

The effects of low-level laser therapy (LLLT) on tumor growth are inconsistent. In this study, we investigated the effects of LLLT on melanoma tumor growth and angiogenesis. C57/BL6 mice were challenged with B16F10 melanoma cells and treated with LLLT for 5 consecutive days; untreated mice were used as controls. Tumor weight, angiogenesis, immunohistochemistry, and protein levels were compared between the treated and untreated mice. In an in vitro experiment, B16F10 cells were treated with LLLT. Proteins were extracted and subjected to Western blot analysis for analyzing signaling pathways. Compared with the findings in the untreated mice, tumor weight substantially increased in the treated mice. Both immunohistochemical and Western blot analyses revealed markedly increased levels of CD31, a biomarker of vascular differentiation, in the LLLT group. In B16F10 cells, LLLT considerably induced the phosphorylation of extracellular signal-regulated kinase (ERK), which, in turn, phosphorylated p38 mitogen-activated protein kinase (MAPK). Furthermore, LLLT induced the expression of vascular endothelial growth factor, but not hypoxia-inducible factor-1α, through the ERK/p38 MAKP signaling pathways. Our findings indicate that LLLT induces melanoma tumor growth by promoting angiogenesis. Therefore, it should be avoided in patients with melanoma.

Effectiveness of Photobiomodulation Therapy on Neuropathic Pain, Nerve Conduction and Plantar Pressure Distribution in Diabetic Peripheral Neuropathy - A Systematic Review

BACKGROUND

Diabetic peripheral neuropathy is a severe complication of type 2 diabetes mellitus. The most common symptoms are neuropathic pain and altered sensorium due to damage to small nerve fibers. Altered plantar pressure distribution is also a major risk factor in diabetic peripheral neuropathy, leading to diabetic foot ulcers.

OBJECTIVE

The objective of this systematic review was to analyze the various studies involving photobiomodulation therapy on neuropathic pain and plantar pressure distribution in diabetic peripheral neuropathy.

METHODS

We conducted a systematic review (PubMed, Web of Science, CINAHL, and Cochrane) to summarise the evidence on photobiomodulation therapy for Diabetic Peripheral Neuropathy with type 2 diabetes mellitus. Randomized and non-randomized studies were included in the review.

RESULTS

This systematic review included eight studies in which photobiomodulation therapy showed improvement in neuropathic pain and nerve conduction velocity. It also reduces plantar pressure distribution, which is a high risk for developing foot ulcers.

CONCLUSION

We conclude that photobiomodulation therapy is an effective, non-invasive, and costefficient means to improve neuropathic pain and altered plantar pressure distribution in diabetic peripheral neuropathy.

Method to analyze effects of low-level laser therapy on biological cells with a digital holographic microscope

Low-level laser therapy (LLLT) is a therapeutic tool that uses the photobiochemical interaction between light and tissue. Its effectiveness is controversial due to a strong dependence on dosimetric parameters. In this work, we demonstrate that digital holographic microscopy is an effective label-free imaging technique to analyze the effects of LLLT on biological cells, and we propose the full methodology to create correct synthetic aperture phase maps for further extensive, highly accurate statistical analysis. The proposed methodology has been designed to provide a basis for many other biological experiments using quantitative phase imaging. We use SHSY-5Y and HaCaT cells irradiated with different doses of red light for the experiment. The analysis shows quantitative changes in cell dry mass density and the projected cell surface in response to different radiation doses.

Red and near infrared light-stimulated angiogenesis mediated via Ca2+ influx, VEGF production and NO synthesis in endothelial cells in macrophage or malignant environments

Irradiation with red or near-infrared (NIR) light in low level light therapy (LLLT) is found to stimulate cellular processes and bioenergetics, resulting in enhanced wound healing, pain control, neurodegenerative diseases treatment, etc. During light irradiation of tissues and organs, different cells are affected, though the connection between photostimulation of cells and their environmental conditions remains poorly understood. In this report, red/NIR light-stimulated angiogenesis is investigated using endothelial cells in vitro, with a focus on the capillary-like structure (CLS) formation and the respective biochemical processes in cells under conditions proximate to a healthy or malignant environment, which strongly defines angiogenesis. To model environmental conditions for endotheliocytes in vitro, the cell culture environment was supplemented by an augmented conditioned medium from macrophages or cancer cells. The biochemical processes in endothelial cell cultures were investigated with and without irradiation by red (650 nm) and near-infrared (808 nm) laser diodes and under normoxia or hypoxia conditions. A light-stimulated angiogenesis has been found, with a more efficient stimulation by 650 nm light compared to 808 nm light. It was shown that the irradiation with light promoted extracellular Ca²⁺ influx, fostered cell cycle progression, proliferation and NO generation in endothelial cells, and caused an increase in vascular endothelial growth factor (VEGF) production by endothelial cells and M2 macrophages under hypoxia conditions. The activation of VEGF production by macrophages was found to be associated with an increase in the number of M2 macrophages after light irradiation under hypoxia conditions. Thus, a new pathway of an activation of the endothelial cell metabolism, which is related with the extracellular Ca²⁺ influx after light irradiation, has been revealed. STATEMENT OF SIGNIFICANCE: Red/NIR light-stimulated angiogenesis has been studied using endothelial cells in vitro, with focus on CLS formation and the respective biochemical processes in cell models proximate to a healthy or malignant environment. A light-stimulated angiogenesis has been found, stimulated via extracellular Ca²⁺ influx, cell cycle progression, proliferation and NO generation, VEGF production increase by endothelial cells under hypoxia conditions.

Dosage Effects of an 810 nm Diode Laser on the Proliferation and Growth Factor Expression of Human Gingival Fibroblasts

Introduction: A substantial amount of evidence supports the positive effect of photobiomodulation on the proliferation and differentiation of various cell types. Several laser wavelengths have been used for wound healing improvement, and their actual outcome depends on the settings utilized during irradiation. However, the heterogeneous wavelengths and laser settings applied in the existing literature make it difficult to draw solid conclusions and comparison of different studies. The aim of the present study is to evaluate and compare the effects of various doses of laser energy, provided by an 810 nm diode, on human gingival fibroblasts in terms of proliferation and expression of growth factors with a pivotal role in wound healing. Methods: Human gingival fibroblasts were cultured on plastic tissue culture and irradiated with 2, 4, 6 or 12 J/cm². The effects of the low-level laser therapy (LLLT) using an 810 nm diode laser on growth factor expression (EGF, TGF and VEGF) were evaluated by qPCR at 72 hours and 7 days after irradiation. Cell proliferation was evaluated at 24, 48 and 72 hours after LLLT using MTT assay. Results: Energy density of 12 J/cm² provoked irradiated gingival fibroblasts to demonstrate significantly higher proliferation as well as higher gene expression of Col1, VEGF and EGF. LLLT positive effects were obvious up to 7 days post-irradiation. Conclusion: LLLT with 810 nm presents beneficial effects on proliferation, collagen production and growth factor expression in human gingival fibroblast cells. The application of 12 J/cm² can be suggested as the optimal energy density for the enhancement of the wound healing process.

Experimental and Clinical Applications of Red and Near-Infrared Photobiomodulation on Endothelial Dysfunction: A Review

BACKGROUND

Under physiological conditions, endothelial cells are the main regulator of arterial tone homeostasis and vascular growth, sensing and transducing signals between tissue and blood. Disease risk factors can lead to their unbalanced homeostasis, known as endothelial dysfunction. Red and near-infrared light can interact with animal cells and modulate their metabolism upon interaction with mitochondria's cytochromes, which leads to increased oxygen consumption, ATP production and ROS, as well as to regulate NO release and intracellular Ca²⁺ concentration. This medical subject is known as photobiomodulation (PBM). We present a review of the literature on the in vitro and in vivo effects of PBM on endothelial dysfunction.

METHODS

A search strategy was developed consistent with the PRISMA statement. The PubMed, Scopus, Cochrane, and Scholar electronic databases were consulted to search for in vitro and in vivo studies.

RESULTS

Fifty out of >12,000 articles were selected.

CONCLUSIONS

The PBM can modulate endothelial dysfunction, improving inflammation, angiogenesis, and vasodilatation. Among the studies, 808 nm and 18 J (0.2 W, 2.05 cm²) intracoronary irradiation can prevent restenosis as well as 645 nm and 20 J (0.25 W, 2 cm²) can stimulate angiogenesis. PBM can also support hypertension cure. However, more extensive randomised controlled trials are necessary.

Hypoxia up-regulates VEGF ligand and downregulates VEGF soluble receptor mRNA expression in bovine granulosa cells in vitro

Oxygen concentration (0₂) in antral ovarian follicles is below that found in most tissues, which is important for adequate granulosa cell function. The VEGF system is linked to angiogenesis and responds to changing 0₂ by stimulating neovascularization when levels are low. However, in the avascular granulosa cell layer of the follicle, VEGF action is directed to stimulating cell viability and steroidogenesis. The aim of this study was to examine the effect of 0₂ concentration on granulosa cell expression of the VEGF-system components. Bovine granulosa cells were isolated from medium-sized follicles (4-7 mm in diameter), placed in McCoy 5a medium supplemented with 10 ng/mL of insulin, 1 ng/mL of IGF-I, and 1 ng/mL of FSH, and cultured in four well plates (500 thousand cells per well), on three separate occasions. Culture plates were placed in gas-impermeable jars with a gas mixture containing either 2%, or 5% of O₂, or under atmospheric air condition inside an incubator (20% of 0₂). Media was replaced at 48 h of culture and cells from the plate in each oxygen concentration were pooled for RNA extraction after 96 h. The number of mRNA copies for the VEGF-system components - including ligands (VEGF120, VEGF120b, VEGF165 and VEGF165b), enzymes (cyclin-dependent like kinases-1, CLK1 and serine-arginine protein kinase 1, SRPK1), splicing factors (serine-arginine-rich splicing factors, SRSF1 and SRSF6), and the membrane-bound (VEGFR1, VEGFR2) and soluble forms of the receptors (sVEGFR1 and sVEGFR2) were quantified by qPCR. Granulosa cells cultured with low 0₂ (2%) had a higher expression of VEGF ligands (P < 0.05) when compared to cells cultured at 20% 0₂. VEGF164b mRNA was absent in granulosa cells from all culture conditions. The 2 and 5% 0₂ levels, which coincide with physiological concentrations, in the ovarian follicle, induced higher SRSF6 expression than atmospheric 0₂ concentrations (20%, P < 0.05). In contrast, mRNA copies for SRPK1, CLK1, SRSF1, VEGFR1 or VEGFR2 did not differ between 0₂ culture conditions. (P > 0.05). Nonetheless, mRNA copies for the soluble receptors, sVEGFR1 and sVEGFR2, linearly increased (P < 0.05) with 0₂ concentration. These results suggest that when cultured under hypoxic conditions, granulosa cells may develop an autocrine milieu that favors VEGF's biological effects on their survival and function.

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

Light energy is harnessed for therapeutic use in a number of ways, most recently by way of photobiomodulation (PBM). This phenomenon is a cascade of physiological events induced by the nonthermal exposure of tissue to light at the near infrared end of the visible spectrum. Therapeutic PBM has become a highly commercialized interest, marketed for everything from facial rejuvenation to fat loss, and diode-based devices are popular in both the clinic setting and for use at home. The lack of regulatory standards makes it difficult to draw clear conclusions about efficacy and safety but it is crucial that we understand the theoretical basis for PBM, so that we can engage in an honest dialogue with our patients and design better clinical studies to put claims of efficacy to the test. This article presents a summary of the science of PBM and examines the differences between laser light, on which much of the preclinical evidence is based and light from diodes, which are typically used in a clinical setting.

In Vitro Cytological Responses against Laser Photobiomodulation for Periodontal Regeneration

Periodontal disease is a chronic inflammatory disease caused by periodontal bacteria. Recently, periodontal phototherapy, treatment using various types of lasers, has attracted attention. Photobiomodulation, the biological effect of low-power laser irradiation, has been widely studied. Although many types of lasers are applied in periodontal phototherapy, molecular biological effects of laser irradiation on cells in periodontal tissues are unclear. Here, we have summarized the molecular biological effects of diode, Nd:YAG, Er:YAG, Er,Cr:YSGG, and CO₂ lasers irradiation on cells in periodontal tissues. Photobiomodulation by laser irradiation enhanced cell proliferation and calcification in osteoblasts with altering gene expression. Positive effects were observed in fibroblasts on the proliferation, migration, and secretion of chemokines/cytokines. Laser irradiation suppressed gene expression related to inflammation in osteoblasts, fibroblasts, human periodontal ligament cells (hPDLCs), and endothelial cells. Furthermore, recent studies have revealed that laser irradiation affects cell differentiation in hPDLCs and stem cells. Additionally, some studies have also investigated the effects of laser irradiation on endothelial cells, cementoblasts, epithelial cells, osteoclasts, and osteocytes. The appropriate irradiation power was different for each laser apparatus and targeted cells. Thus, through this review, we tried to shed light on basic research that would ultimately lead to clinical application of periodontal phototherapy in the future.

Phototherapy as a Rational Antioxidant Treatment Modality in COVID-19 Management; New Concept and Strategic Approach: Critical Review

The COVID-19 pandemic has taken the entire globe by storm. The pathogenesis of this virus has shown a cytokine storm release, which contributes to critical or severe multi-organ failure. Currently the ultimate treatment is palliative; however, many modalities have been introduced with effective or minimal outcomes. Meanwhile, enormous efforts are ongoing to produce safe vaccines and therapies. Phototherapy has a wide range of clinical applications against various maladies. This necessitates the exploration of the role of phototherapy, if any, for COVID-19. This critical review was conducted to understand COVID-19 disease and highlights the prevailing facts that link phototherapy utilisation as a potential treatment modality for SARS-CoV-2 viral infection. The results demonstrated phototherapy's efficacy in regulating cytokines and inflammatory mediators, increasing angiogenesis and enhancing healing in chronic pulmonary inflammatory diseases. In conclusion, this review answered the following research question. Which molecular and cellular mechanisms of action of phototherapy have demonstrated great potential in enhancing the immune response and reducing host-viral interaction in COVID-19 patients? Therefore, phototherapy is a promising treatment modality, which needs to be validated further for COVID-19 by robust and rigorous randomised, double blind, placebo-controlled, clinical trials to evaluate its impartial outcomes and safety.

Photobiomodulation alters the viability of HUVECs cells

The aim of the present study was to investigate the influence of low-level red (660 nm) and infrared (780 nm) laser with four different radiance exposures on human umbilical vein endothelial cells (HUVECs) in vitro. HUVECs (1.5 × 10⁴) were incubated in 96-well culture plates. The cells were maintained in M199 medium supplemented with 20% fetal bovine serum, 1% antibiotic (penicillin), 1% anti-mycotic (Fungizone), and 1% endothelial cell growth supplement. After centrifugation, irradiations (660/780 nm, 40 mW, 1, 5, 10, and 20 J/cm², 1 s, 5 s, 10 s, and 20 s, respectively, total energy 0.4 J, 2 J, 4 J, and 8 J, and beam spot size at target 0.04 cm²) were performed at the bottom of Falcon tubes such that the laser beam directly reached the cell without passing through the culture medium. The cells were divided into groups based on radiant exposures. Cell viability and protein concentration were verified after 1, 2, 3, 6, 8, and 10 days. Red laser increased the cell viability and protein concentration in all groups (three-way ANOVA, p < 0.05) beginning on the second day. The greatest peak compared with the control was found when the radiant exposure was 5 J/cm² and 10 J/cm². Infrared laser inhibited cell viability and modulated the protein concentration in the cells, with the highest peak protein concentration found on the second day in the group with radiant exposure of 1 J/cm² and 10 J/cm² (three-way ANOVA, p < 0.05). Red laser increased the viability and concentration of total proteins in HUVECs, whereas infrared laser had an inhibitory effect on cell viability, while maintaining the total protein concentration similar to that found in the control group.

Laser phototherapy induces angiogenesis in the periodontal tissue after delayed tooth replantation in rats

Background

Laser phototherapy (LPT) has been suggested as a new therapeutic tool to improve the repair of replanted teeth. However, its effects and mechanism of action are not yet completely understood.

Objectives

This study evaluated histologically the effect of laser phototherapy (LPT) λ808 and λ660 nm on angiogenesis in the periodontal tissue of replanted teeth in rats.

Material and Methods

Twenty maxillary right incisors were extracted from twenty Wistar rats and randomly assigned to four groups (n = 5): PN - teeth were stored in paper napkin for 45 min; WM - teeth were immersed in 20 ml of UHT whole cow milk for 45 min; PNL and WML - teeth received the same treatment described for PN and WM, respectively, plus LPT at λ808 and λ660 nm. All root canals were prepared and filled with calcium hydroxide paste. The animals were euthanized 15 days after tooth replantation and angiogenesis was scored by blood vessel counting in the area of periodontal ligament and alveolar bone, using the ImageJ software. Data were analyzed statistically by ANOVA and Tukey's test (α = 5%).

Results

LPT at λ808 and λ660 nm caused significant increased angiogenesis on irradiated groups (PNL and WML) when compared to the non-irradiated groups (PN and WM) (p<0.05). There was no statistically significant difference between PN and WM as well as between PNL and WML (p>0.05).

Conclusions

LPT is capable of stimulating angiogenesis in vivo in the periodontal tissue of replanted teeth. Key words:Angiogenesis, lasers, tooth avulsion, tooth replantation, wound healing.

Low-level laser irradiation at a high power intensity increased human endothelial cell exosome secretion via Wnt signaling

The distinct role of low-level laser irradiation (LLLI) on endothelial exosome biogenesis remains unclear. We hypothesize that laser irradiation of high dose in human endothelial cells (ECs) contributes to the modulation of exosome biogenesis via Wnt signaling pathway. When human ECs were treated with LLLI at a power density of 80 J/cm², the survival rate reduced. The potential of irradiated cells to release exosomes was increased significantly by expressing genes CD63, Alix, Rab27a, and b. This occurrence coincided with an enhanced acetylcholine esterase activity, pseudopodia formation, and reduced zeta potential value 24 h post-irradiation. Western blotting showed the induction of LC3 and reduced level of P62, confirming autophagy response. Flow cytometry and electron microscopy analyses revealed the health status of the mitochondrial function indicated by normal ΔΨ activity without any changes in the transcription level of PINK1 and Optineurin. When cells exposed to high power laser irradiation, p-Akt/Akt ratio and in vitro tubulogenesis capacity were blunted. PCR array and bioinformatics analyses showed the induction of transcription factors promoting Wnt signaling pathways and GTPase activity. Thus, LLLI at high power intensity increased exosome biogenesis by the induction of autophagy and Wnt signaling. LLLI at high power intensity increases exosome biogenesis by engaging the transcription factors related to Wnt signaling and autophagy stimulate.

Low-level laser therapy prevents endothelial cells from TNF-α/cycloheximide-induced apoptosis

Low-level laser therapy (LLLT), widely used in physiotherapy, has been known to enhance wound healing and stimulate cell proliferation, including fibroblast and endothelial cells. Applying LLLT can increase cell proliferation in many kinds of cells including fibroblasts and endothelial cells. However, the protective mechanisms of LLLT on endothelial apoptosis remain unclear. We hypothesized LLLT can protect endothelial cells from inflammation-induced apoptosis. Human endothelial cell line, EA.hy926 cells, and TNF-α/cycloheximide (TNF/CHX) were used to explore the protective effects of LLLT (660 nm) on inflammation-induced endothelial apoptosis. Cell viability, apoptosis, caspase-3/7/8/9 activity, MAPKs signaling, NF-κB activity, and inducible/endothelial nitric oxide synthase (iNOS/eNOS) expression were measured. Our results showed that LLLT increased EA.hy926 cell proliferation, attenuated the TNF/CHX-induced apoptosis, and reduced the TNF/CHX-mediated caspase-3/7/8/9 activation. In addition, LLLT increased ERK MAPK phosphorylation and suppressed the TNF/CHX-increased p38 MAPK, JNK, IKK phosphorylation, NF-κB translocation, and iNOS expression. The caspases-3 cleavage and cell death were not increased in cells treating with ERK inhibitor U0126, which implicated that ERK is not to be responsible for the protective effects of LLLT. After treating with p38 mitogen-activated protein kinase (MAPK) activator, the protection of LLLT in cell apoptosis was no longer existed, showing that LLLT protected the endothelial cells by suppressing p38 MAPK signaling. Our results provide a new insight into the possible molecular mechanisms in which LLLT protects against inflammatory-induced endothelial dysfunction.

Scattering and absorption control in biocompatible fibers towards equalized photobiomodulation

Transparent tissue scaffolds enable illumination of growing tissue to accelerate cell proliferation and improve other cell functions through photobiomodulation. The biphasic dose response of cells exposed to photobiomodulating light dictates that the illumination be evenly distributed across the scaffold such that the cells are neither under nor over exposed to light. However, equalized illumination has not been sufficiently addressed. Here we analyze and experimentally demonstrate spatially equalizing illumination by three methods, namely: engineered surface scattering, reflection by a gold mirror, and traveling-waves in a ring mesh. Our results show that nearly equalized illumination is achievable by controlling the light scattering-to-loss ratio. This demonstration furthers opportunities for dose-optimized photobiomodulation in tissue regeneration.

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

CONTEXT

Identification of factors that enhance the proliferation of human dental mesenchymal stem cells (DMSCs) is vital to facilitate tissue regeneration. The role of low-level laser irradiation (LLLI) on proliferation of human DMSCs has not been well established.

OBJECTIVE

To assess the effect of LLLI on proliferation of human DMSCs when applied in-vitro.

DATA SOURCES

Electronic search of literature was conducted (2000-2016) on PubMed, Web of Science, and Scopus databases. Search terms included low-level light therapy, low-level laser irradiation, low-level light irradiation, LLLT, humans, adolescent, adult, cells, cultured, periodontal ligament, dental pulp, stem cells, dental pulp stem cells, mesenchymal stem cells, periodontal ligament stem cell, deciduous teeth, cell proliferation, adult stem cells, radiation, and proliferation.

RESULTS

The literature search identified 165 studies with 6 being eligible for inclusion; all used diode lasers; 5 studies used InGaAIP diode lasers; 4 used 660nm, and the other two applied 810nm or 980nm wavelength LLLI. The distance between the DMSCs and the laser spot ranged between 0.5mm to 2mm. The time intervals of cell proliferation analysis ranged from 0h to 7days after LLLI. After 660nm LLLI, an increase in the DMSC's proliferation was reported [DMSCs extracted from dental pulp of deciduous teeth (two irradiations, 3J/cm(2), 20mW was more effective than 40mW), adult teeth (two irradiations, 0.5 and 1.0J/cm(2), 30mW), and from adult periodontal ligament (two irradiations, 1.0J/cm(2) was more effective than 0.5J/cm(2), 30mW)]. Similarly, an increase in the proliferation of DMSCs extracted from dental pulp of adult teeth was reported after 810nm LLLI (7 irradiations in 7days, 0.1 and 0.2J/cm(2), 60mW) or 980nm LLLI (single irradiation, 3J/cm(2), 100mW). However, 660nm LLLI in one study did not increase the proliferation of DMSCs (single irradiation, energy densities of 0.05, 0.30, 7, and 42J/cm(2), 28mW).

CONCLUSION

There is limited evidence that in-vitro LLLI (660/810/980nm, with energy densities of 0.1-3J/cm(2)) increases the proliferation of DMSCs. Considering the limited evidence and their method heterogeneity it is difficult to reach a firm conclusion. Further research is necessary to identify the optimal characteristics of the LLLI setting (wave length, energy density, power output, frequency/duration of irradiations, distance between the cells and the laser spot/probe) to increase proliferation of DMSCs, and assess its impact on replicative senescence, as well as determine feasibility of the use in the clinical setting.

Effect of the transdermal low-level laser therapy on endothelial function

The effect of low-level laser therapy (LLLT) on the cardiovascular system is not fully established. Since the endothelium is an important endocrine element, establishing the mechanisms of LLLT action is an important issue.The aim of the study was to evaluate the effect of transdermal LLLT on endothelial function.In this study, healthy volunteers (n = 40, age = 20–40 years) were enrolled. N = 30 (14 female, 16 male, mean age 30 ± 5 years) constituted the laser-irradiated group (LG). The remaining 10 subjects (6 women, 4 men, mean age 28 ± 5 years) constituted the control group (CG). Participants were subjected to LLLT once a day for three consecutive days. Blood for biochemical assessments was drawn before the first irradiation and 24 h after the last session. In the LG, transdermal illumination of radial artery was conducted (a semiconductor laser λ = 808 nm, irradiation 50 mW, energy density 1.6 W/cm² and a dose 20 J/day, a total dose of 60 J). Biochemical parameters (reflecting angiogenesis: vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), angiostatin; antioxidative status: glutathione (GSH) and the nitric oxide metabolic pathway: symmetric dimethylarginine (SDMA), asymmetric dimethylarginine (ADMA) and l-arginine) were assessed. In the LG, a significant increase in GSH levels and considerable decrease in angiostatin concentration following the LLLT were observed. No significant differences in levels of the VEGF, FGF, SDMA, ADMA were observed.LLLT modifies vascular endothelial function by increasing its antioxidant and angiogenic potential. We found no significant differences in levels of the nitric oxide pathway metabolites within 24 h following the LLLT irradiation.

Low-level laser irradiation effect on endothelial cells under conditions of hyperglycemia

Diabetes mellitus is considered to be a very serious lifestyle disease leading to cardiovascular complications and impaired wound healing observed in the diabetic foot syndrome. Chronic hyperglycemia is the source of the endothelial activation. The inflammatory process in diabetes is associated with the secretion of inflammatory cytokines by endothelial cells, e.g., tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6). The method of phototherapy using laser beam of low power (LLLT-low-level laser therapy) effectively supports the conventional treatment of diabetic vascular complications such as diabetic foot syndrome. The aim of our study was to evaluate the effect of low-power laser irradiation at two wavelengths (635 and 830 nm) on the secretion of inflammatory factors (TNF-α and IL-6) by the endothelial cell culture-HUVEC line (human umbilical vein endothelial cell)-under conditions of hyperglycemia. It is considered that adverse effects of hyperglycemia on vascular endothelial cells may be corrected by the action of LLLT, especially with the wavelength of 830 nm. It leads to the reduction of TNF-α concentration in the supernatant and enhancement of cell proliferation. Endothelial cells play an important role in the pathogenesis of diabetes; however, a small number of studies evaluate an impact of LLLT on these cells under conditions of hyperglycemia. Further work on this subject is warranted.