Improvement of full-thickness rat skin wounds by photobiomodulation therapy (PBMT): A dosimetric study

Photobiomodulation, Transmucosal Laser Irradiation of Blood, or B complex as alternatives to treat Covid-19 Related Long-Term Taste Impairment: double-blind randomized clinical trial

COVID-19 Related Long-Term Taste Impairment (CRLTTI) is a condition that can be expressed after COVID-19 contagion, lasting for months or even years, affecting the routine and quality of life of individuals. Participants expressing CRLTTI, with a minimum of 2 months, attested by PCR-RT test were assessed for taste and smell, and underwent experimental treatments in 6 distinct groups: Photobiomodulation (PBM) in tongue dorsum and lateral (660 nm, 808 nm, association of 660 and 808 nm), Transmucosal Laser Irradiation of Blood (TLIB)-ventral surface of tongue (660 nm), B complex supplementation, and Sham laser. No intergroup statistical differences were observed at the final evaluation, despite the tendencies of better results with PBM and TLIB observed. PBM, TLIB, and B complex might be treatment options in the management of CRLTTI, despite the lack of total remission of taste and smell perception after 8 sessions (PBM and TLIB) or 30 days of B complex supplementation.

Does Photobiomodulation Affects CK10 and CK14 in Oral Mucositis Radioinduced Repair?

The mechanisms of action of photobiomodulation (PBM) in oral mucositis (OM) are not completely elucidated. To enlighten the role of PBM in the evolution of epithelial maturity in OM ulcers, the present study evaluated the effect of PBM with red (λ) wavelength of 660 nanometers (nm) and infrared of 780 nm in radio-induced OM wounds on the tongue of rats, eight and twenty days after irradiation with single dose of 20 Gy. The percentage area corresponding to positive staining for cytokeratin 10 (CK10) and 14 (CK14) proteins was evaluated in the epithelial area of the lesions, using an immunohistochemical technique (IHC), 8 and 20 days after the induction of lesions, and compared with an untreated control group. CK10 was significantly more expressed in the group treated with 660 nm PBM. CK14 did not show quantitative differences between the groups evaluated. However, whereas in the groups treated with PBM, CK14 was already restricted to the basal layer of the epithelium, as expected in healthy epithelia, in control group it was also expressed in upper layers of the epithelium. In this work, PBM was able to improve epithelial maturity of the repaired OM wound, especially in the 660 nm group.

Designing Deferoxamine-Loaded Flaxseed Gum and Carrageenan-Based Controlled Release Biocomposite Hydrogel Films for Wound Healing

In this study, biocomposite hydrogel films made from flaxseed gum (FSG)/kappa carrageenan (CGN) were fabricated, using potassium chloride as a crosslinker and glycerol as a plasticizer. The composite films were loaded with deferoxamine (DFX), an iron chelator that promotes neovascularization and angiogenesis for the healing of wounds. The properties of the biocomposite hydrogel films, including swelling, solubility, water vapor transmission rate, tensile strength, elongation at break, and Young’s modulus studies, were tested. The films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). In addition, drug release studies in PBS at pH 7.2 were investigated. In vivo analysis was performed by assessing the wound contraction in a full-thickness excisional wound rat model. Hematoxylin & eosin (H & E) and Masson’s trichome staining were performed to evaluate the effect of the films on wound healing progress. The visual and micro-morphological analysis revealed the homogenous structure of the films; however, the elongation at break property decreased within the crosslinked film but increased for the drug-loaded film. The FTIR analysis confirmed the crosslinking due to potassium chloride. A superior resistance towards thermal degradation was confirmed by TGA for the crosslinked and drug-loaded films. Drug release from the optimum film was sustained for up to 24 h. In vivo testing demonstrated 100% wound contraction for the drug-loaded film group compared to 72% for the pure drug solution group. In light of the obtained results, the higher potential of the optimized biocomposite hydrogel film for wound healing applications was corroborated.

5G Electromagnetic Radiation Attenuates Skin Melanogenesis In Vitro by Suppressing ROS Generation

Recently, the impacts of 5G electromagnetic radiation (EMR) with 28 GHz on human health have been attracting public attention with the advent of 5G wireless communication. Here, we report that 5G (28 GHz) EMR can attenuate the skin pigmentation in murine melanoma cells (B16F10) and a 3D pigmented human epidermis model (Melanoderm™). B16 cells were exposed to 5G (28 GHz) with or without α-MSH for 4 h per day. Interestingly, 5G attenuated α-MSH-induced melanin synthesis. Fontana-Masson staining confirmed that the dendritic formation of α-MSH stimulated B16 cells was diminished by 5G exposure. To confirm the anti-melanogenic effect of 5G EMR, MelanoDerm™ was irradiated with 5G at a power intensity of 10 W/m² for 4 h a day for 16 days and melanin distribution was detected with Fontana-Masson staining, which supported the anti-melanogenic effect of 5G EMR. Consistently, 5G EMR suppressed α-MSH induced upregulation of melanogenic enzymes; tyrosinase, TRP-1, and TRP-2. Of note, 5G EMR attenuated ROS production stimulated by α-MSH and H₂O₂, suggesting that 5G EMR may dissipate ROS generation, which is pivotal for the melanin synthesis. Collectively, we demonstrated that 5G EMR can attenuate skin pigmentation by attenuating ROS generation.

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

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

Assessment of wound area reduction on chronic wounds in dogs with photobiomodulation therapy: A randomized controlled clinical trial

Background and Aim

Chronic wounds are a clinical problem and require intensive standard wound care. However, this is sometimes insufficient to promote healing. Photobiomodulation therapy (PBMT) can be used as an adjunctive therapy to improve wound healing. Various PBMT devices with different properties and parameter settings as well as different animal species can influence a variety of clinical outcomes. This study aims to assess the use of 830 nm PBMT or simultaneous superpulsed and multiple wavelengths (SPMW; 660, 875, and 905 nm) PBMT on chronic wounds in client-owned dogs.

Materials and Methods

This study included 21 client-owned dogs with chronic wounds allocated into three groups: (1) Control group (C) treated with irrigated saline and without PBMT (n=7); (2) L1 group treated with irrigated saline together with the radiation of 830 nm PBMT (n=7); and (3) L2 group treated with irrigated saline together with the radiation of simultaneous SPMW-PBMT (n=7). Wound healing was assessed on the basis of wound size reduction as a percentage of wound area every 2^nd day for 15 days using image analysis software (ImageJ software^®, National Institutes of Health, Rockville, Maryland, USA).

Results

A significant difference in the percentage of wound area reduction was noted between the C and PBMT groups (L1 and L2; p<0.05). The average percentages of wound area reduction at the end of the study (15 days) were 42.39±20.58, 56.98±24.82, and 61.81±27.18 in the C, L1, and L2 groups, respectively. A steady decrease in wound size was noted in both PBMT and non-PBMT groups, and coefficients were 7.77, 8.95, and 10.01 in the C, L1, and L2 groups, respectively. The percentage of wound area reduction was found to be significantly different between the PBMT and non-BPMT groups on day 7 (p<0.05).

Conclusion

Based on the results of the current study, using either 830 nm PBMT or simultaneous SPMW-PBMT can accelerate the chronic wound healing process in dogs with a significant reduction in wound area. Therefore, it can be used as an adjunctive therapy to improve wound healing in dogs with reduced treatment duration.

Wound healing process with different photobiomodulation therapy protocols to treat 5-FU-induced oral mucositis in hamsters

OBJECTIVES

The aim of this study was to analyze the effects of three different Photobiomodulation Therapy (PBMT) protocols in the treatment of 5-fluorouracil-induced oral mucositis in hamsters.

DESIGN

60 hamsters were divided into five groups: group "C", which did not receive oral mucosa scratching, 5-fluorouracil (5-FU) or PBMT; group "Ch", which received anesthesia, superficial oral mucosa scratching and 5-FU (oral mucositis induction); and three groups that received oral mucositis induction and a PBMT protocol: groups ChLI, ChLII and ChLIII that received 0.24 J (one point), 1 J (one point) and 1.2 J (five points of 0.24 J) of energy, respectively. The laser equipment used had λ = 660 nm and 0.04 cm² of spot area (0.226 cm diameter). The animals were euthanized on days 7 and 10 of the experiment, and their oral mucosas were removed for histological (light microscopy and collagen staining), immunohistochemical (NF-kB and TNF-α), and biochemical (TNF-α, NF-kB and hydroxyproline) analysis.

RESULTS

Group ChLI (less energy), showed the most accelerated repair rates and a lower concentration of inflammatory biomarkers than group Ch. Comparing the three PBMT protocols for treatment of 5-FU-induced oral mucositis in hamsters, the one with low energy (0.24 J) showed better results, regarding reduction of inflammatory biomarkers and tissue repair, than the ones with higher energy (1 and 1.2 J).

Evaluation of antimicrobial photodynamic therapy on wounds infected by Staphylococcus aureus in animal models

BACKGROUND

Antibiotic-resistant Staphylococcus aureus bacteria are one of the expanding challenges. The purpose of current study is to evaluate the antimicrobial effect of photodynamic therapy (aPDT) on wounds infected to Staphylococcus aureus.

METHODS

In this study, 40 six-month-old rats were divided into 4 groups: control, photosensitizer (PS), laser, and aPDT. A full-thickness wound was created on their skin and it was infected by Staphylococcus aureus. For aPDT, the Indocyanine Green (Germany, Nürnberg, A.R.C. Laser, EmunDo) photosensitive agent and laser diod 810 nm (Germany, Nürnberg, A.R.C. Laser) was utilized. The wound healing procedure was monitored every 24 h until the 12th day with photography. The number of the bacteria was counted on the 12th day also. All results were compared using ANOVA and Tukey post hoc tests. Significance level was considered P-Value < 0.05.

RESULTS

The average area of wound reduced in days 5-11th in photosensitizer, laser, and aPDT, respectively. The absolute colonization rate of bacteria in the wounds showed a significant decrease in two groups laser and aPDT compared to the control group. However, the lowest value was for the aPDT.

CONCLUSION

In the conditions of this study, it emerged that aPDT and laser have an antimicrobial effect against antibiotic-resistant bacteria (particularly Staphylococcus aureus) and improve wound healing.