The effects of low-level laser irradiation on cellular viability and proliferation of human skin fibroblasts cultured in high glucose mediums

Investigation of healing strategies in a rat corneal opacity model with polychromatic light and stem cells injection

Corneal opacities are a major cause of vision loss worldwide. However, the current therapies are suboptimal to manage the corneal wound healing process. Therefore, there is an obvious need to develop new treatment strategies that are efficient in promoting wound healing in patients with severe corneal disorders. In this study, we investigated and compared the efficacy of adipose-derived mesenchymal stem cells (ADMSCs) and photobiomodulation (PBM) with polychromatic light in the NIR (600-1200 nm) alone and in combination, on corneal opacity, inflammatory response, and tissue architecture in a rat corneal opacity model created by mechanical injury. All animals were divided into four groups randomly following the injury: injury only (no treatment), ADMSCs treatment, PBM treatment and combined (ADMSCs+PBM) treatment (n = 12 eyes per group). At the 10th and 30th day following injury, corneal opacity formation, neovascularization, and corneal thickness were assessed. On the 30th day the harvested corneas were analyzed by transmission electron microscopy (TEM), histological evaluation, immunohistochemical (IHC) staining and real-time polymerase chain reaction (RT-PCR). On day 30, the corneal opacity score, neovascularization grade, and corneal thickness in all treatment groups were significantly lower in comparison with the untreated injured corneas. The TEM imaging and H&E staining together clearly revealed a significant enhancement in corneal regeneration with improved corneal microenvironment and reduced vascularization in the combined administration of PBM and ADMSCs compared to treatment of PBM and ADMSCs alone. In addition, the IHC staining, and RT-PCR analysis supported our hypothesis that combining ADMSCs therapy with PBM alleviated the inflammatory response, and significantly decreased scar formation compared to either ADMSCs or PBM alone during the corneal wound healing.

Effect of photobiomodulation therapy on the morphology, intracellular calcium concentration, free radical generation, apoptosis and necrosis of human mesenchymal stem cells-an in vitro study

The aim of the study was to investigate the impact of multiwave locked system (MLS M1) emitting synchronized laser radiation at 2 wavelength simultaneous (λ = 808 nm, λ = 905 nm) on the mesenchymal stem cells (MSCs). Human MSCs were exposed to MLS M1 system laser radiation with the power density 195-318 mW/cm2 and doses of energy 3-20 J, in continuous wave emission (CW) or pulsed emission (PE). After irradiation exposure in doses of energy 3 J, 10 J (CW, ƒ = 1000 Hz), and 20 J (ƒ = 2000 Hz), increased proliferation of MSCs was observed. Significant reduction of Fluo-4 Direct™ Ca2+ indicator fluorescence over controls after CW and PE with 3 J, 10 J, and 20 J was noticed. A decrease in fluorescence intensity after the application of radiation with a frequency of 2000 Hz in doses of 3 J, 10 J, and 20 J was observed. In contrary, an increase in DCF fluorescence intensity after irradiation with laser radiation of 3 J, 10 J, and 20 J (CW, ƒ = 1000 Hz and ƒ = 2000 Hz) was also shown. Laser irradiation at a dose of 20 J, emitted at 1000 Hz and 2000 Hz, and 3 J emitted at a frequency of 2000 Hz caused a statistically significant loss of MSC viability. The applied photobiomodulation therapy induced a strong pro-apoptotic effect dependent on the laser irradiation exposure time, while the application of a sufficiently high-energy dose and frequency with a sufficiently long exposure time significantly increased intracellular calcium ion concentration and free radical production by MSCs.

An evaluation of photobiomodulation effects on human gingival fibroblast cells under hyperglycemic condition: an in vitro study

An in vitro study was designed to evaluate the effects of photobiomodulation (PBM) with 915-nm diode laser on human gingival fibroblast (HGF) cells under hyperglycemic condition. The HGF cells were cultured in Dulbecco's modified eagle medium (DMEM) medium containing 30 mM glucose concentration for 48 h to mimic the hyperglycemic condition. Subsequently, the cells received three sessions of PBM (915 nm, continuous emission mode, 200 mW, energy density values of 3.2, 6, and 9.2 J/cm2). Twenty-four hours post-irradiation, cell proliferation, expression of interleukin 6 (IL-6), and vascular endothelial growth factor (VEGF) were assessed with MTT and real-time polymerase chain reaction (PCR) tests, respectively. Also, reactive oxygen species (ROS) production was measured using CM-H2DCFDA fluorimetry. No changes were detected in the cell proliferation rate between the high glucose control group and laser-treated cells, while VEGF and IL-6 gene expression levels increased significantly after PBM in the high glucose-treated cells group. ROS level was significantly decreased in the irradiated cells in high-glucose medium compared with the high glucose control group. Our study revealed the inductive role of 915-nm-mediated PBM on VEGF and the inflammatory response while concurrently reducing reactive oxygen species production in HGF cells in hyperglycemic conditions.

The effects of polarized photobiomodulation on cellular viability, proliferation, mitochondrial membrane potential and apoptosis in human fibroblasts: Potential applications to wound healing

Photobiomodulation (PBM) is a widely used therapeutic intervention used to treat several chronic conditions. Despite this, fundamental research underpinning its effectiveness is lacking, highlighted by the lack of a definitive mechanism of action. Additionally, there are many treatment variables which remain underexplored, one of those being the effect of polarization the property of light that specifies the direction of the oscillating electric field. When applied to PBM, using linearly polarized light, when compared to otherwise identical non-polarized light, may enhance its biological efficacy. As such, we investigated the potential biological effects of polarized PBM when compared to non-polarized and non-irradiated controls in the domains of cellular viability, proliferation, apoptosis and mitochondrial membrane potential (ΔΨ) within cells exposed to oxidative stress. It was noted that polarized PBM, when compared to non-polarized PBM and non-irradiated controls, demonstrated mostly increased levels of cellular proliferation and ΔΨ, whilst decreasing the amount of cellular apoptosis. These results indicate that polarization may have utility in the clinical application of PBM. Future research is needed to further elucidate the underpinning mechanisms of PBM and polarization.

The Effects of Photobiomodulation on Bone Defect Repairing in a Diabetic Rat Model

The purpose of this study is to examine the prospective therapeutic effects of photobiomodulation on the healing of bone defects in diabetic mellitus (DM) using rat models to provide basic knowledge of photobiomodulation therapy (PBMT) during bone defect repair. For in vitro study, an Alizzarin red stain assay was used to evaluate the effect of PBMT on osteogenic differentiation. For in vivo study, micro-computed tomography (microCT) scan, H&E and IHC stain analysis were used to investigate the effect of PBMT on the healing of the experimental calvarial defect (3 mm in diameter) of a diabetic rat model. For in vitro study, the high glucose groups showed lower osteogenic differentiation in both irradiated and non-irradiated with PBMT when compared to the control groups. With the PBMT, all groups (control, osmotic control and high glucose) showed higher osteogenic differentiation when compared to the non-irradiated groups. For in vivo study, the hyperglycemic group showed significantly lower bone regeneration when compared to the control group. With the PBMT, the volume of bone regeneration was increasing and back to the similar level of the control group. The treatment of PBMT in 660 nm could improve the bone defect healing on a diabetic rat calvarial defect model.

Biological Responses of Stem Cells to Photobiomodulation Therapy

BACKGROUND

Stem cells have attracted the researchers interest, due to their applications in regenerative medicine. Their self-renewal capacity for multipotent differentiation, and immunomodulatory properties make them unique to significantly contribute to tissue repair and regeneration applications. Recently, stem cells have shown increased proliferation when irradiated with low-level laser therapy or Photobiomodulation Therapy (PBMT), which induces the activation of intracellular and extracellular chromophores and the initiation of cellular signaling. The purpose of this study was to evaluate this phenomenon in the literature.

METHODS

The literature investigated the articles written in English in four electronic databases of PubMed, Scopus, Google Scholar and Cochrane up to April 2019. Stem cell was searched by combining the search keyword of "low-level laser therapy" OR "low power laser therapy" OR "low-intensity laser therapy" OR "photobiomodulation therapy" OR "photo biostimulation therapy" OR "LED". In total, 46 articles were eligible for evaluation.

RESULTS

Studies demonstrated that red to near-infrared light is absorbed by the mitochondrial respiratory chain. Mitochondria are significant sources of reactive oxygen species (ROS). Mitochondria play an important role in metabolism, energy generation, and are also involved in mediating the effects induced by PBMT. PBMT may result in the increased production of (ROS), nitric oxide (NO), adenosine triphosphate (ATP), and cyclic adenosine monophosphate (cAMP). These changes, in turn, initiate cell proliferation and induce the signal cascade effect.

CONCLUSION

The findings of this review suggest that PBMT-based regenerative medicine could be a useful tool for future advances in tissue engineering and cell therapy.

In Vitro Evidences of Different Fibroblast Morpho-Functional Responses to Red, Near-Infrared and Violet-Blue Photobiomodulation: Clues for Addressing Wound Healing

Although photobiomodulation (PBM) has proven promising to treat wounds, the lack of univocal guidelines and of a thorough understanding of light–tissue interactions hampers its mainstream adoption for wound healing promotion. This study compared murine and human fibroblast responses to PBM by red (635 ± 5 nm), near-infrared (NIR, 808 ± 1 nm), and violet-blue (405 ± 5 nm) light (0.4 J/cm2 energy density, 13 mW/cm2 power density). Cell viability was not altered by PBM treatments. Light and confocal laser scanning microscopy and biochemical analyses showed, in red PBM irradiated cells: F-actin assembly reduction, up-regulated expression of Ki67 proliferation marker and of vinculin in focal adhesions, type-1 collagen down-regulation, matrix metalloproteinase-2 and metalloproteinase-9 expression/functionality increase concomitant to their inhibitors (TIMP-1 and TIMP-2) decrease. Violet-blue and even more NIR PBM stimulated collagen expression/deposition and, likely, cell differentiation towards (proto)myofibroblast phenotype. Indeed, these cells exhibited a higher polygonal surface area, stress fiber-like structures, increased vinculin- and phospho-focal adhesion kinase-rich clusters and α-smooth muscle actin. This study may provide the experimental groundwork to support red, NIR, and violet-blue PBM as potential options to promote proliferative and matrix remodeling/maturation phases of wound healing, targeting fibroblasts, and to suggest the use of combined PBM treatments in the wound management setting.

Photobiomodulation with 808-nm diode laser enhances gingival wound healing by promoting migration of human gingival mesenchymal stem cells via ROS/JNK/NF-κB/MMP-1 pathway

Photobiomodulation (PBM) has been shown to improve wound healing by promoting mesenchymal stem cell migration and proliferation. However, it remains unknown whether an 808-nm diode laser can influence human gingival mesenchymal stem cells (HGMSCs), and which dose this works well. In the present study, it was found that PBM could promote the migration of HGMSCs but not the proliferation. Furthermore, PBM could activate mitochondrial ROS, which could elevate the phosphorylation levels of JNK and IKB in HGMSCs, and further activate NF-κB as the nuclear translocation of p65 is elevated. Taken together, these present results indicate that PBM might promote cell migration via the ROS/JNK/NF-κB pathway.

Efficacy of Biophysical Energies on Healing of Diabetic Skin Wounds in Cell Studies and Animal Experimental Models: A Systematic Review

We have systematically assessed published cell studies and animal experimental reports on the efficacy of selected biophysical energies (BPEs) in the treatment of diabetic foot ulcers. These BPEs include electrical stimulation (ES), pulsed electromagnetic field (PEMF), extracorporeal shockwave (ECSW), photo energies and ultrasound (US). Databases searched included CINAHL, MEDLINE and PubMed from 1966 to 2018. Studies reviewed include animal and cell studies on treatment with BPEs compared with sham, control or other BPEs. Information regarding the objective measures of tissue healing and data was extracted. Eighty-two studies were eventually selected for the critical appraisal: five on PEMF, four each on ES and ECSW, sixty-six for photo energies, and three about US. Based on the percentage of original wound size affected by the BPEs, both PEMF and low-level laser therapy (LLL) demonstrated a significant clinical benefit compared to the control or sham treatment, whereas the effect of US did not reveal a significance. Our results indicate potential benefits of selected BPEs in diabetic wound management. However, due to the heterogeneity of the current clinical trials, comprehensive studies using well-designed trials are warranted to confirm the results.

Photobiomodulation of a flowable matrix in a human skin ex vivo model demonstrates energy-based enhancement of engraftment integration and remodeling

The use of dermal substitutes to treat skin defects such as ulcers has shown promising results, suggesting a potential role for skin substitutes for treating acute and chronic wounds. One of the main drawbacks with the use of dermal substitutes is the length of time from engraftment to graft take, plus the risk of contamination and failure due to this prolonged integration. Therefore, the use of adjuvant energy-based therapeutic modalities to augment and accelerate the rate of biointegration by dermal substitute engraftments is a desirable outcome. The photobiomodulation (PBM) therapy modulates the repair process, by stimulating cellular proliferation and angiogenesis. Here, we evaluated the effect of PBM on a collagen-glycosaminoglycan flowable wound matrix (FWM) in an ex vivo human skin wound model. PBM resulted in accelerated rate of re-epithelialization and organization of matrix as seen by structural arrangement of collagen fibers, and a subsequent increased expression of alpha-smooth muscle actin (α-SMA) and vascular endothelial growth factor A (VEGF-A) leading to an overall improved healing process. The use of PBM promoted a beneficial effect on the rate of integration and healing of FWM. We therefore propose that the adjuvant use of PBM may have utility in enhancing engraftment and tissue repair and be of value in clinical practice.

Laser parameters for efficient biomedical stimulation: A study to increase cognitive response rate

BACKGROUND:

The laser is able to irradiate the exact amount of stimulation to an area by a non contact method, and has the advantage of being able to stimulate the local target area.

OBJECTIVE:

This study examined an efficient method of laser tactile stimulation using laser parameter combinations.

METHODS:

The laser parameters that could cause an increase in the cognitive response rate of human subjects were examined without increasing the amount of total laser energy.

RESULTS:

As a result, the appropriate matching parameters such as duty ratio, pulse frequency, and exposure time of laser pulses showed a dominant influence in effectively increasing the tactile response rate of subjects with limited amount of total laser energy.

CONCLUSIONS:

This study can be applied to neurophysiology, cognitive research, and clinical laser application.

Cell Adhesion Molecules are Mediated by Photobiomodulation at 660 nm in Diabetic Wounded Fibroblast Cells

Diabetes affects extracellular matrix (ECM) metabolism, contributing to delayed wound healing and lower limb amputation. Application of light (photobiomodulation, PBM) has been shown to improve wound healing. This study aimed to evaluate the influence of PBM on cell adhesion molecules (CAMs) in diabetic wound healing. Isolated human skin fibroblasts were grouped into a diabetic wounded model. A diode laser at 660 nm with a fluence of 5 J/cm² was used for irradiation and cells were analysed 48 h post-irradiation. Controls consisted of sham-irradiated (0 J/cm²) cells. Real-time reverse transcription (RT) quantitative polymerase chain reaction (qPCR) was used to determine the expression of CAM-related genes. Ten genes were up-regulated in diabetic wounded cells, while 25 genes were down-regulated. Genes were related to transmembrane molecules, cell–cell adhesion, and cell–matrix adhesion, and also included genes related to other CAM molecules. PBM at 660 nm modulated gene expression of various CAMs contributing to the increased healing seen in clinical practice. There is a need for new therapies to improve diabetic wound healing. The application of PBM alongside other clinical therapies may be very beneficial in treatment.

Photobiomodulation alters matrix protein activity in stressed fibroblast cells in vitro

A balance is maintained between matrix synthesis and degradation, and a prolonged increase in matrix metalloproteinases (MMPs) affects healing. Photobiomodulation (PBM) speeds up healing and alters wound environment. The study aimed to determine changes in protein and gene expression of collagen type 1 (Col-I), MMP-3 and -9 and TIMP-1 in fibroblasts irradiated at 660 or 830 nm. Commercially purchased human skin fibroblast cells were modeled into five groups namely, normal, normal wounded, diabetic wounded, hypoxic wounded and diabetic hypoxic wounded. Control cells were sham irradiated. Laser irradiation was conducted at 660 or 830 nm (108/or 94 mW, 9.1 cm² , 420/or 483 s) with 5 J/cm² . Forty-eight hours post-irradiation, protein expression of TIMP-1, MMP-3, -9 and Col-I was determined by flow cytometry and immunofluorescence, and gene expression by real-time RT-PCR. There was an increase in TIMP-1 and Col-I, and a decrease in MMP-3 and -9, as well as an alteration in mRNA expression of MMP3, MMP9, TIMP1 and COL1A1 in irradiated cells. Due to the responsiveness of the diabetic hypoxic wounded model, the findings propose this model as appropriate for wound healing studies and suggest that PBM promotes the remodeling phase of wound healing by decreasing matrix degradation and upregulating synthesis.

A Low-Level Carbon Dioxide Laser Promotes Fibroblast Proliferation and Migration through Activation of Akt, ERK, and JNK

BACKGROUND

Low-level laser therapy (LLLT) with various types of lasers promotes fibroblast proliferation and migration during the process of wound healing. Although LLLT with a carbon dioxide (CO2) laser was also reported to promote wound healing, the underlying mechanisms at the cellular level have not been previously described. Herein, we investigated the effect of LLLT with a CO2 laser on fibroblast proliferation and migration.

MATERIALS AND METHODS

Cultured human dermal fibroblasts were prepared. MTS and cell migration assays were performed with fibroblasts after LLLT with a CO2 laser at various doses (0.1, 0.5, 1.0, 2.0, or 5.0 J/cm2) to observe the effects of LLLT with a CO2 laser on the proliferation and migration of fibroblasts. The non-irradiated group served as the control. Moreover, western blot analysis was performed using fibroblasts after LLLT with a CO2 laser to analyze changes in the activities of Akt, extracellular signal-regulated kinase (ERK), and Jun N-terminal kinase (JNK), which are signaling molecules associated with cell proliferation and migration. Finally, the MTS assay, a cell migration assay, and western blot analysis were performed using fibroblasts treated with inhibitors of Akt, ERK, or JNK before LLLT with a CO2 laser.

RESULTS

In MTS and cell migration assays, fibroblast proliferation and migration were promoted after LLLT with a CO2 laser at 1.0 J/cm2. Western blot analysis revealed that Akt, ERK, and JNK activities were promoted in fibroblasts after LLLT with a CO2 laser at 1.0 J/cm2. Moreover, inhibition of Akt, ERK, or JNK significantly blocked fibroblast proliferation and migration.

CONCLUSIONS

These findings suggested that LLLT with a CO2 laser would accelerate wound healing by promoting the proliferation and migration of fibroblasts. Activation of Akt, ERK, and JNK was essential for CO2 laser-induced proliferation and migration of fibroblasts.

Low-level laser therapy with helium-neon laser improved viability of osteoporotic bone marrow-derived mesenchymal stem cells from ovariectomy-induced osteoporotic rats

The purpose of this study was to evaluate the influences of helium–neon (He–Ne) and infrared (IR) lasers on the viability and proliferation rate of healthy and ovariectomy-induced osteoporotic (OVX) bone marrow mesenchymal stem cells (BMMSCs) in vitro. MSCs harvested from the BM of healthy and OVX rats were culture expanded. He–Ne and IR lasers were applied three times at energy densities of 0.6, 1.2, and 2.4??J/cm2 for BMMSCs. BMMSCs viability and proliferation rate were evaluated by MTT assay on days 2, 4, 6, 14, and 21. The results showed that healthy BMMSCs responded optimally to 0.6??J/cm2 using an IR laser after three times of laser radiation. Moreover, it was found that OVX-BMMSCs responded optimally to 0.6??J/cm2 with He–Ne laser and one-time laser radiation. It is concluded that the low-level laser therapy (LLLT) effect depends on the physiological state of the BMMSCs, type of the laser, wavelength, and number of laser sessions. The biostimulation efficiency of LLLT also depends on the delivered energy density. LLLT can enhance the viability and proliferation rate of healthy and especially osteoporotic autologous BMMSCs, which could be very useful in regenerative medicine.

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.

Photobiomodulation devices for hair regrowth and wound healing: a therapy full of promise but a literature full of confusion

Photobiomodulation is reported to positively influence hair regrowth, wound healing, skin rejuvenation and psoriasis. Despite rapid translation of this science to commercial therapeutic solutions, significant gaps in our understanding of the underlying processes remain. The aim of this review was to seek greater clarity and rationality specifically for the selection of optical parameters for studies on hair regrowth and wound healing. Our investigation of 90 reports published between 1985 and 2015 revealed major inconsistencies in optical parameters selected for clinical applications. Moreover, poorly understood photoreceptors expressed in skin such as cytochrome c oxidase, cryptochromes, opsins etc. may trigger different molecular mechanisms. All this could explain the plethora of reported physiological effects of light. To derive parameters for optimal clinical efficacy of photobiomodulation, we recommend a more rational approach to underpin clinical studies, with research on molecular targets and pathways using well-defined biological model systems to enable translation of optical parameters from in vitro to in vivo. Furthermore, special attention needs to be paid when conducting studies for hair regrowth, aiming for double-blind, placebo-controlled randomized clinical trials as the gold standard for quantifying hair growth.

Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy

Photobiomodulation (PBM) also known as low-level laser (or light) therapy (LLLT), has been known for almost 50 years but still has not gained widespread acceptance, largely due to uncertainty about the molecular, cellular, and tissular mechanisms of action. However, in recent years, much knowledge has been gained in this area, which will be summarized in this review. One of the most important chromophores is cytochrome c oxidase (unit IV in the mitochondrial respiratory chain), which contains both heme and copper centers and absorbs light into the near-infra-red region. The leading hypothesis is that the photons dissociate inhibitory nitric oxide from the enzyme, leading to an increase in electron transport, mitochondrial membrane potential and ATP production. Another hypothesis concerns light-sensitive ion channels that can be activated allowing calcium to enter the cell. After the initial photon absorption events, numerous signaling pathways are activated via reactive oxygen species, cyclic AMP, NO and Ca2+, leading to activation of transcription factors. These transcription factors can lead to increased expression of genes related to protein synthesis, cell migration and proliferation, anti-inflammatory signaling, anti-apoptotic proteins, antioxidant enzymes. Stem cells and progenitor cells appear to be particularly susceptible to LLLT.

Combined effects of low-level laser therapy and human bone marrow mesenchymal stem cell conditioned medium on viability of human dermal fibroblasts cultured in a high-glucose medium

Low-level laser therapy (LLLT) exhibited biostimulatory effects on fibroblasts viability. Secretomes can be administered to culture mediums by using bone marrow mesenchymal stem cells conditioned medium (BM-MSCs CM). This study investigated the combined effects of LLLT and human bone marrow mesenchymal stem cell conditioned medium (hBM-MSCs CM) on the cellular viability of human dermal fibroblasts (HDFs), which was cultured in a high-glucose (HG) concentration medium. The HDFs were cultured either in a concentration of physiologic (normal) glucose (NG; 5.5 mM/l) or in HG media (15 mM/l) for 4 days. LLLT was performed with a continuous-wave helium-neon laser (632.8 nm, power density of 0.00185 W/cm(2) and energy densities of 0.5, 1, and 2 J/cm(2)). About 10% of hBM-MSCs CM was added to the HG HDF culture medium. The viability of HDFs was evaluated using dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. A significantly higher cell viability was observed when laser of either 0.5 or 1 J/cm(2) was used to treat HG HDFs, compared to the control groups. The cellular viability of HG-treated HDFs was significantly lower compared to the LLLT + HG HDFs, hBM-MSCs CM-treated HG HDFs, and LLLT + hBM-MSCs CM-treated HG HDFs. In conclusion, hBM-MSCs CM or LLLT alone increased the survival of HG HDFs cells. However, the combination of hBM-MSCs CM and LLLT improved these results in comparison to the conditioned medium.

Short-term effects of extremely low-frequency pulsed electromagnetic field and pulsed low-level laser therapy on rabbit model of corneal alkali burn

This study was conducted to investigate the effect of combining extremely low frequency-pulsed electromagnetic field (ELF-PEMF) and low-level laser therapy (LLLT) on alkali-burned rabbit corneas. Fifty alkali-burned corneas of 50 rabbits were categorized into five groups: ELF-PEMF therapy with 2 mT intensity (ELF 2) for 2 h daily; LLLT for 30 min twice daily; combined ELF-PEMF and LLLT (ELF + LLLT); medical therapy (MT); and control (i.e., no treatment). Clinical examination and digital photography of the corneas were performed on days 0, 2, 7, and 14. After euthanizing the rabbits, the affected eyes were evaluated by histopathology. The clinical and histopathologic results were compared between the groups. On days 7 and 14, no significant difference in the corneal defect area was evident between the ELF, LLLT, ELF + LLLT, and MT groups. Excluding the controls, none of the study groups demonstrated a significant corneal neovascularization in both routine histopathology and immunohistochemistry for CD31. Keratocyte loss was significantly higher in the MT group than in the ELF, LLLT, and ELF + LLLT groups. Moderate to severe stromal inflammation in the LLLT group was comparable with that in the MT group and was significantly lower than that in the other groups. In conclusion, combining LLLT and ELF was not superior to ELF alone or LLLT alone in healing corneal alkali burns. However, given the lower intensity of corneal inflammation and the lower rate of keratocytes loss with LLLT, this treatment may be superior to other proposed treatment modalities for healing alkali-burned corneas.

Effects of low-level laser irradiation on proliferation and functional protein expression in human RPE cells

Low-level laser irradiation (LLLI) modulates a set of biological effects in many cell types such as fibroblasts, keratinocytes, and stem cells. However, no study to date has reported the effects of LLLI on retinal pigment epithelia (RPE) cells. The aim of this study was to investigate whether LLLI could enhance the proliferation of RPE cells and increase the expression of RPE functional genes/proteins. Human ARPE-19 cells were seeded overnight and treated with 8 J/cm(2) of LLLI. Cell proliferation was measured by CCK8 assay and cell cycle distribution was evaluated by FACS. The transcription of cell cycle-specific genes and RPE functional genes was quantified by RT-PCR. Moreover, the expression of ZO-1 and CRALBP were evaluated by immunostaining. A dose of 8 J/cm(2) of LLLI significantly increased proliferation and promoted cell cycle progression while upregulating the transcription of CDK4 and CCND1 and decreasing the transcription of CDKN2A, CDKN2C, and CDKN1B in human ARPE-19 cells. Additionally, LLLI enhanced the expression of ZO-1 and CRALBP in human ARPE-19 cells. In conclusion, LLLI could enhance the proliferative ability of human ARPE-19 cells by modulating cyclin D1, CDK4, and a group of cyclin-dependent kinase inhibitors. It also could increase the expression of RPE-specific proteins. Thus, LLLI may be a potential approach for the treatment of RPE degenerative diseases.

Organic light emitting diode improves diabetic cutaneous wound healing in rats

A major complication for diabetic patients is chronic wounds due to impaired wound healing. It is well documented that visible red wavelengths can accelerate wound healing in diabetic animal models and patients. In vitro and in vivo diabetic models were used to investigate the effects of organic light emitting diode (OLED) irradiation on cellular function and cutaneous wound healing. Human dermal fibroblasts were cultured in hyperglycemic medium (glucose concentration 180 mM) and irradiated with an OLED (623 nm wavelength peak, range from 560 to 770 nm, power density 7 or 10 mW/cm2 at 0.2, 1, or 5 J/cm2). The OLED significantly increased total adenosine triphosphate concentration, metabolic activity, and cell proliferation compared with untreated controls in most parameters tested. For the in vivo experiment, OLED and laser (635 ± 5 nm wavelength) treatments (10 mW/cm2 , 5 J/cm2 daily for a total of seven consecutive days) for cutaneous wound healing were compared using a genetic, diabetic rat model. Both treatments had significantly higher percentage of wound closure on day 6 postinjury and higher total histological scores on day 13 postinjury compared with control. No statistical difference was found between the two treatments. OLED irradiation significantly increased fibroblast growth factor-2 expression at 36-hour postinjury and enhanced macrophage activation during initial stages of wound healing. In conclusion, the OLED and laser had comparative effects on enhancing diabetic wound healing.

Shedding light on a new treatment for diabetic wound healing: a review on phototherapy

Impaired wound healing is a common complication associated with diabetes with complex pathophysiological underlying mechanisms and often necessitates amputation. With the advancement in laser technology, irradiation of these wounds with low-intensity laser irradiation (LILI) or phototherapy, has shown a vast improvement in wound healing. At the correct laser parameters, LILI has shown to increase migration, viability, and proliferation of diabetic cells in vitro; there is a stimulatory effect on the mitochondria with a resulting increase in adenosine triphosphate (ATP). In addition, LILI also has an anti-inflammatory and protective effect on these cells. In light of the ever present threat of diabetic foot ulcers, infection, and amputation, new improved therapies and the fortification of wound healing research deserves better prioritization. In this review we look at the complications associated with diabetic wound healing and the effect of laser irradiation both in vitro and in vivo in diabetic wound healing.