Photobiomodulation of Human Fibroblasts and Keratinocytes with Blue Light: Implications in Wound Healing

The effect of continuous long-term illumination with visible light in different spectral ranges on mammalian cells

One of the biggest challenges in tissue engineering and regenerative medicine is to ensure oxygen supply of cells in the (temporary) absence of vasculature. With the vision to exploit photosynthetic oxygen production by microalgae, co-cultivated in close vicinity to oxygen-consuming mammalian cells, we are searching for culture conditions that are compatible for both sides. Herein, we investigated the impact of long-term illumination on mammalian cells which is essential to enable photosynthesis by microalgae: four different cell types-primary human fibroblasts, dental pulp stem cells, and osteoblasts as well as the murine beta-cell line INS-1-were continuously exposed to warm white light, red or blue light over seven days. We observed that illumination with red light has no adverse effects on viability, metabolic activity and growth of the cells whereas exposure to white light has deleterious effects that can be attributed to its blue light portion. Quantification of intracellular glutathione did not reveal a clear correlation of this effect with an enhanced production of reactive oxygen species. Finally, our data indicate that the cytotoxic effect of short-wavelength light is predominantly a direct effect of cell illumination; photo-induced changes in the cell culture media play only a minor role.

Photobiomodulation CME part II: Clinical applications in dermatology

Photobiomodulation (PBM) is an emerging treatment modality in dermatology with increasing office and home-based use. PBM is the use of various light sources in the red light (620-700 nm) and near-infrared (700-1440 nm) spectrum as a form of light therapy. PBM is often administered through low-level lasers or light-emitting diodes. Studies show that PBM can be used effectively to treat conditions secondary to cancer therapies, alopecia, ulcers, herpes simplex virus, acne, skin rejuvenation, wounds, and scars. PBM offers patients many benefits compared to other treatments. It is noninvasive, cost-effective, convenient for patients, and offers a favorable safety profile. PBM can be used as an alternative or adjuvant to other treatment modalities including pharmacotherapy. It is important for dermatologists to gain a better clinical understanding of PBM for in-office administration and to counsel patients on proper application for home-use devices to best manage safety and expectations as this technology develops. PBM wavelengths can induce varied biological effects in diverse skin types, races, and ethnicities; therefore, it is also important for dermatologists to properly counsel their skin of color patients who undergo PBM treatments. Future clinical trials are necessary to produce standardized recommendations across conditions and skin types.

Effects of photobiomodulation with blue Light Emitting Diode (LED) on the healing of skin burns

The management of skin burns is still challenging. Among the therapeutic methods used, there are topical treatments with pharmacological and herbal agents, low-intensity therapeutic ultrasound, use of biomaterials, reconstructive techniques and photobiomodulation therapy. The aim of this study was to evaluate the effects of photobiomodulation with blue Light Emitting Diode (LED) on burn healing. Fifty Wistar rats were divided into control (CTRL) (n = 25) and blue LED (LED) (n = 25), with subgroups (n = 5) for each time of euthanasia (7, 14, 21, 28 and 32 days). Treated animals were daily irradiated (470 nm, 1W, 0.44 W/cm2, 50 J/cm2). Clinical evaluations were performed and the Wound Retraction Index (WRI) was determined. Histological sections were submitted to hematoxylin-eosin, toluidine blue and the immunohistochemical technique, with anti-α-SMA and anti-TGF-β1 antibodies. All data were directly collected by previously calibrated evaluators in a blind manner. The values were included in a statistical program. For all statistical tests used, 5% significance level (p < 0.05) was considered. No statistically significant differences in WRI between groups were observed (p > 0.05). Re-epithelialization was higher using LED at 7 and 14 days (p < 0.05) and greater amount of inflammatory cells was observed at 7 days (p = 0.01). With LED at 21 and 32 days, greater number of mast cells were observed (p < 0.05), as well as smaller number of myofibroblasts at 14, 21, 28 and 32 days (p < 0.05) and lower percentage of TGF-β1 positive cells in the conjunctiva at 7, 14 and 21 days (p < 0.05). Negative correlations were observed in LED between the percentage of TGF-β1 in the epithelium and the mean number of inflammatory cells and number of myofibroblasts (p < 0.05). The results suggest that, depending on the period, blue LED can modulate the healing processes of third-degree skin burns, such as re-epithelialization, inflammatory response, mast cell concentration, myofibroblast differentiation and TGF-β1 immunoexpression. Despite these effects, this therapy does not seem to have significant influence on the retraction of these wounds. Future studies, using different protocols, should be carried out to expand the knowledge about the photobiomodulatory mechanisms of this type of light in the healing process.

The implication of blue light-emitting diode on mesenchymal stem cells: a systematic review

The application of blue light (400-480 nm) in photobiotherapy remains controversial. This systematic review aimed to collect and analyze the biological effects of blue light-emitting diode (LED) on mesenchymal stem cells (MSCs). Inclusion and exclusion criteria were formulated, and relevant English articles from January 1982 to September 2022 were searched in PubMed, Scopus, and Web of Science. Nine articles with a medium (n = 4) to low (n = 5) risk of bias were included. Most of the MSCs reported were derived from human tissue; only one article used MSCs derived from mouse. The wavelength of the LED used was in the 400-480 nm range, and the irradiation modes were continuous (n = 8) and pulse waves (n = 1). A chiral polarizer was used in one such study in which the irradiance was 14 mW/cm2 and the irradiation time was 24 h. The energy densities used in other studies were between 0.378 and 72 J/cm2, and the irradiation times were between 10 and 3600 s. Blue LED light can inhibit proliferation and promote differentiation of MSCs in an appropriate energy density range, which may be related to the activation of transient receptor potential vanilloid 1 (TRPV1). Additionally, polarized light may reduce the toxic effects of blue light on MSCs. However, the heterogeneity of the design schemes and LED parameters, as well as the small number of studies, limited the conclusiveness of the review. Therefore, further studies are needed to determine the optimal irradiation strategy for promoting MSC function.

Ear keloids: An innovative 3-steps combined treatment

INTRODUCTION

An excessive proliferation of fibroblasts and collagen synthesis after an injury may lead to a benign fibrous tumor, known as keloid, which does not regress spontaneously. Earlobes are a very frequent site of onset, since after a trauma (i.e., piercing) keloids may develop either on the helix and on the anterior or posterior lobe, from a few months up to several years after the injury.

OBJECTIVES

To report the effectiveness of a combined protocol of CO2 laser + Dye laser + a portable Blue LED Light medical device for Photobiomodulation Therapy (EmoLED®).

METHODS

Fifty-two patients with a total of 56 ear keloids have been treated in the same session with a single CO2 laser procedure + a pulsed Dye laser procedure with an adjunctive EmoLED® procedure for 3 up to 6 min. A monthly follow-up has been performed with an adjunctive EmoLED® session in case of signs of inflammation.

RESULTS

Among 56 treated keloids, 89.3% of them (50/56) did not recur during a follow-up period (from 6 up to 24 months, mean 16.3 months) while six keloids recurred (6/56, 10.7%) with mild thickening of the scar, thus requiring further treatments.

CONCLUSIONS

Even if an excellent outcome obtained by the synergistic effect of combined laser treatments has already been described (i.e., CO2 laser + Dye Laser), the present study showed the adjuvant procedure with EmoLED® can reduce significantly the risk of keloids recurrences.

Effect of blue light on the cell viability of A549 lung cancer cells and investigations into its possible mechanism

Blue light has attracted extensive attention as a new potential cancer therapy. Recent studies have indicated that blue light has a significant inhibition effect on A459 cells. However, the effect of light parameters on the treatment of A549 cells and the mechanism of how blue light made the effect was still unclear. This study aimed to investigate A549 cells responses to blue light with varying irradiance and dose-dense, and tried to find out the mechanism of the effects blue light made. The results suggested that the responses of A549 cells to blue light with different irradiance and dose-dense were different and the decrease of cell viability reached saturation when the irradiance reached 3 mW/cm2 and the dose-dense reached 3.6 J/cm2 . It was assumed that blue light suppressed PI3K/AKT pathway and promoted the expression of JNK and p53 to affect the proliferation of A549 cells.

Photodynamic Therapy with Aminolevulinic Acid Enhances the Cellular Activity of Cells Cultured on Porcine Acellular Dermal Matrix Membranes Used in Periodontology

This study aims to test a photodynamic protocol based on a gel containing aminolevulinic acid followed by red-LED (ALAD-PDT) irradiation on human gingival fibroblasts (hGFs) and osteoblasts (hOBs) cultured on a porcine acellular dermal matrix membrane (PADMM). In the previous literature, ALAD-PDT showed solid antibacterial activity and proliferative induction on HGFs cultured on plates and HOBs cultured on a cortical lamina. PADMMs are used in dentistry and periodontology to treat gingival recessions and to increase the tissue thickness in the case of a thin biotype without the risks or postoperative discomfort associated with connective tissue grafts. However, one of the possible complications in this type of surgery is represented by bacterial invasion and membrane exposition during the healing period. We hypothesized that the addition of ALAD-PDT to PADMMs could enhance more rapid healing and decrease the risks connected with bacterial invasion. In periodontal surgery, PADMMs are inserted after a full-thickness flap elevation between the bone and the flap. Consequently, all procedures were performed in parallel on hOBs and hGFs obtained by dental patients. The group control (CTRL) was represented by the unexposed cells cultured on the membranes, group LED (PDT) were the cells subjected to 7 min of red LED irradiation, and ALAD-PDT were the cells subjected to 45 min of ALAD incubation and then to 7 min of red LED irradiation. After treatments, all groups were analyzed for MTT assay and subjected to histological examination at 3 and 7 days and to the SEM observations at 3, 7, and 14 days. Different bone mineralization assays were performed to quantify the effects of ALAD-PDT on hOBs: ALP activity, ALP gene expression, osteocalcin, and alizarin red. The effects of ALAD-PDT on hGFs were evaluated by quantifying collagen 1, fibronectin, and MMP-8. Results showed that ALAD-PDT promoted cellular induction, forming a dense cellular network on hOBs and hGFs, and the assays performed showed statistically significantly higher values for ALAD-PDT with respect to LED alone and CTRLs. In conclusion, ALAD-PDT could represent a promising aid for enhancing the healing of gingival tissues after PADMM applications.

Photobiomodulation with Blue Light on Wound Healing: A Scoping Review

BACKGROUND

Photobiomodulation consists of inducing healing by irradiating light. This scoping review investigates the effect of blue light on the healing process.

METHODS

The MEDLINE, Web of Science, Scopus, and CINAHL databases were searched. Two reviewers independently examined the search results and extracted data from the included studies. A descriptive analysis was performed.

RESULTS

Twenty-two articles were included. Studies were categorized as in vitro/mixed, preclinical, and clinical. The power density used was 10-680 mW/cm² in most of the in vitro/preclinical studies, the irradiation time ranged from 5 s to 10 min, and different wavelengths and energy densities were used. In clinical studies, the wavelength ranged from 405 to 470 nm, and the energy density varied from 1.5 to 30 J/cm².

CONCLUSIONS

A low energy density (<20 J/cm²) was able to stimulate the different cell types and proteins involved in healing, while a high energy density, 20.6-50 J/cm², significantly reduced cell proliferation, migration, and metabolism. There is a great variety of device parameters among studies, and this makes it difficult to conclude what the best technical specifications are. Thus, further studies should be performed in order to define the appropriate parameters of light to be used.

Antimicrobial Formulation of a Bacterial Nanocellulose/Propolis-Containing Photosensitizer for Biomedical Applications

With the aim of contributing to the development of more efficient materials for wound care, new topical formulations based on bacterial nanocellulose (BNC) hydrogels containing propolis were produced. Characterizations confirmed the incorporation of propolis into the BNC matrix, maintaining its structure and properties. Rheological analysis confirmed that the hydrogels showed thixotropic behavior appropriate for topical application. Chromatographic profiles showed sustained release of propolis biomarkers for at least 20 h. The formulations did not present mutagenicity. For application in photodynamic inactivation (PDI), BNC/propolis hydrogels were prepared with the photosensitizers methylene blue (MB). Spectroscopy and confocal fluorescence microscopy confirmed the interaction of MB and propolis in BNC hydrogels, as well as the formation of a new composite material. In the antibacterial assays, formulations containing MB and propolis significantly reduced Staphylococcus aureus growth. In the presence of light, BNC/MB hydrogels completely inhibited the microorganism. Therefore, the results suggest potential materials for the prevention or treatment of Staphylococcus aureus infections in wounds.

Low-Dose Blue Light (420 nm) Reduces Metabolic Activity and Inhibits Proliferation of Human Dermal Fibroblasts

Hypertrophic scarring in burn wounds is caused by overactive fibroblasts and myofibroblasts. Blue light reveals wavelength- and dose-dependent antibacterial and antiproliferative effects and may serve as a therapeutic option against wound infection and fibrotic conditions. Therefore, we evaluated in this study the effects of single and multiple irradiations with blue light at 420 nm (BL₄₂₀) on the intracellular ATP concentration, and on the viability and proliferation of the human skin fibroblast (HDFs). In addition, possible BL₄₂₀-induced effects on the catalase expression and differentiation were assessed by immunocytochemical staining and western blot analyses. Furthermore, we used RNA-seq analyses to identify BL₄₂₀-affected genes. We found that BL₄₂₀ induced toxicity in HDFs (up to 83%; 180 J/cm²). A low dose of 20 J/cm² reduced the ATP concentration by ~50%. Multiple irradiations (4 × 20 J/cm²) inhibited proliferation without visible toxicity and reduced catalase protein expression by ~37% without affecting differentiation. The expression of about 300 genes was significantly altered. Many downregulated genes have functions in cell division/mitosis. BL₄₂₀ can strongly influence the fibroblast physiology and has potential in wound therapy. However, it is important to consider the possible toxic and antiproliferative effects, which could potentially lead to impaired wound healing and reduced scar breaking strength.

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.

Blue-LED-Light Photobiomodulation of Inflammatory Responses and New Tissue Formation in Mouse-Skin Wounds

Background: Recent studies evidence that blue-LED-light irradiation can modulate cell responses in the wound healing process within 24 h from treatment. This study aims to investigate blue-light (410-430 nm) photobiomodulation used in a murine wound model within six days post-treatment. Methods: A superficial wound was made in 30 CD1 male mice. The injuries were treated with a blue LED light (20.6 J/cm²), and biopsies were collected at 24, 72, and 144 h. Histology, fluorescence analysis, and advanced microscopy techniques were used. Results: We can observe an increase in the cellular infiltrate response, and in mast-cell density and their degranulation index correlated to the expression of the major histocompatibility complex after 24 h. Furthermore, after six days, the vessel density increases with the expression of the platelet-derived growth factor in the mast cells. Finally, collagen deposition and morphology in the treated wounds appear more similar to unwounded skin. Conclusions: Blue-light photobiomodulation stimulates several cellular processes that are finely coordinated by mast cells, leading to more rapid wound healing and a better-recovered skin morphology.

The Effects of Blue Light on Human Fibroblasts and Diabetic Wound Healing

Diabetes is a serious threat to global health and is among the top 10 causes of death. The Diabetic foot ulcer (DFU) is among the most common and severe complications of the disease. Bacterial infections are common; therefore, timely aggressive management, using multidisciplinary management approaches is needed to prevent complications, morbidity, and mortality, particularly in view of the growing cases of antibiotic-resistant bacteria. Photobiomodulation (PBM) involves the application of low-level light at specific wavelengths to induce cellular photochemical and photophysical responses. Red and near-infrared (NIR) wavelengths have been shown to be beneficial, and recent studies indicate that other wavelengths within the visible spectrum could be helpful as well, including blue light (400–500 nm). Reports of the antimicrobial activity and susceptibility of blue light on several strains of the same bacterium show that many bacteria are less likely to develop resistance to blue light treatment, meaning it is a viable alternative to antibiotic therapy. However, not all studies have shown positive results for wound healing and fibroblast proliferation. This paper presents a critical review of the literature concerning the use of PBM, with a focus on blue light, for tissue healing and diabetic ulcer care, identifies the pros and cons of PBM intervention, and recommends the potential role of PBM for diabetic ulcer care.

Evaluation of the red & blue LED effects on cutaneous refractory wound healing in male Sprague-Dawley rat using 3 different multi-drug resistant bacteria

OBJECTIVES

Photobiomodulation (PBM) is widely used in clinical therapy, and is an effective approach to resist the bacterial infection of the cutaneous wound and modulate the wound healing process. Due to the several detriments of lasers, Red & Blue LED light (RBLL) may be a more viable light source. This study is aimed to evaluate and compare the therapeutic effect of RBLL light on different multi-drug resistant (MDR) bacteria in vitro and male Sprague-Dawley (SD) rat refractory MDR infection wound model in vivo.

MATERIALS AND METHODS

Methicillin-resistant Staphylococcus aureus (MRSA), Extended-spectrum β-lactamases -producing Escherichia coli (ESBLs-Eco), and the MDR Pseudomonas aeruginosa (MDR-Pae) were employed to evaluate the antibacterial effects of the Blue LED light in vitro. Effects of RBLL on in vivo wound healing were evaluated by analyzing time to closure, wound score, semi-quantitative test for bacterial culture, histopathological examination and Masson staining of skin tissue, immunohistochemical (IHC) staining, and western blot analysis (WB) of wound tissue.

RESULTS

Blue LED light inhibited MRSA, ESBLs-Eco, and MDR-Pae in vitro study. In vivo, RBLL accelerated wound healing, reduced levels of pathogenic bacteria on the wound surface while increasing the blood supply to the wound surface and inhibiting the excessive inflammatory response.

CONCLUSION

RBLL showed a great potential gain for the treatment of MDR bacterial infected wounds, suggesting PBM therapy is an inexpensive, convenient, pain-free, and safe therapeutic intervention for refractory MDR infection wounds.

Photobiomodulation Therapy: A New Light in the Treatment of Systemic Sclerosis Skin Ulcers

INTRODUCTION

Skin ulcers (SU) represent one of the most frequent manifestations of systemic sclerosis (SSc), occurring in almost 50% of scleroderma patients. SSc-SU are often particularly difficult to treat with conventional systemic and local therapies. In this study, a preliminary evaluation of the role and effectiveness of blue light photobiomodulation (PBM) therapy with EmoLED^® in the treatment of scleroderma skin ulcers (SSc-SU) was performed.

METHODS

We retrospectively analyzed 12 consecutive SSc patients with a total of 15 SU on finger hands. All patients were treated with adequate systemic therapy and local treatment for SU; after a standard skin ulcer bed preparation with debridement of all lesions, EmoLED^® was performed. All patients were locally treated every week during 2 months of follow-up; SU data were collected after 4 weeks (T4) and 8 weeks (T8). Eight SSc patients with comparable SU were also evaluated as controls.

RESULTS

The application of EmoLED^® in addition to debridement apparently produced faster healing of SU. Complete healing of SU was recorded in 41.6% cases during EmoLED^® treatment. Significant improvements in SU area, length, and width, wound bed, and related pain were observed in EmoLED^® patients from T0 to T8. Control subjects treated with standard systemic/local therapies merely showed an amelioration of SU area and width at the end of the follow-up. No procedural or post-procedural adverse events were reported.

CONCLUSIONS

The positive clinical results and the absence of side effects suggest that EmoLED^® could be a promising tool in the management of SSc-SU, with an interesting role to play in the healing process in addition to conventional systemic and local treatments.

Metagenomic, Metabolomic, and Functional Evaluation of Kimchi Broth Treated with Light-Emitting Diodes (LEDs)

The light-emitting diode (LED) has been widely used in the food industry, and its application has been focused on microbial sterilization, specifically using blue-LED. The investigation has been recently extended to characterize the biotic and abiotic (photodynamic) effects of different wavelengths. Here, we investigated LED effects on kimchi fermentation. Kimchi broths were treated with three different colored-LEDs (red, green, and blue) or kept in the dark as a control. Multiomics was applied to evaluate the microbial taxonomic composition using 16S rRNA gene amplicon sequencing, and the metabolomic profiles were determined using liquid chromatography–Orbitrap mass spectrometry. Cell viability was tested to determine the potential cytotoxicity of the LED-treated kimchi broths. First, the amplicon sequencing data showed substantial changes in taxonomic composition at the family and genus levels according to incubation (initial condition vs. all other groups). The differences among the treated groups (red-LED (RLED), green-LED (GLED), blue-LED (BLED), and dark condition) were marginal. The relative abundance of Weissella was decreased in all treated groups compared to that of the initial condition, which coincided with the decreased composition of Lactobacillus. Compositional changes were relatively high in the GLED group. Subsequent metabolomic analysis indicated a unique metabolic phenotype instigated by different LED treatments, which led to the identification of the LED treatment-specific and common compounds (e.g., luteolin, 6-methylquinoline, 2-hydroxycinnamic acid, and 9-HODE). These results indicate that different LED wavelengths induce characteristic alterations in the microbial composition and metabolomic content, which may have applications in food processing and storage with the aim of improving nutritional quality and the safety of food.