Does the use of low-level laser influence wound healing in chronic venous leg ulcers?

Unlocking the Power of Light on the Skin: A Comprehensive Review on Photobiomodulation

Photobiomodulation (PBM) is a procedure that uses light to modulate cellular functions and biological processes. Over the past decades, PBM has gained considerable attention for its potential in various medical applications due to its non-invasive nature and minimal side effects. We conducted a narrative review including articles about photobiomodulation, LED light therapy or low-level laser therapy and their applications on dermatology published over the last 6 years, encompassing research studies, clinical trials, and technological developments. This review highlights the mechanisms of action underlying PBM, including the interaction with cellular chromophores and the activation of intracellular signaling pathways. The evidence from clinical trials and experimental studies to evaluate the efficacy of PBM in clinical practice is summarized with a special emphasis on dermatology. Furthermore, advancements in PBM technology, such as novel light sources and treatment protocols, are discussed in the context of optimizing therapeutic outcomes and improving patient care. This narrative review underscores the promising role of PBM as a non-invasive therapeutic approach with broad clinical applicability. Despite the need for further research to develop standard protocols, PBM holds great potential for addressing a wide range of medical conditions and enhancing patient outcomes in modern healthcare practice.

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.

Dressings and topical agents for treating venous leg ulcers

BACKGROUND

Venous leg ulcers are open skin wounds on the lower leg which can be slow to heal, and are both painful and costly. The point prevalence of open venous leg ulcers in the UK is about 3 cases per 10,000 people, and many people experience recurrent episodes of prolonged ulceration. First-line treatment for venous leg ulcers is compression therapy, but a wide range of dressings and topical treatments are also used. This diversity of treatments makes evidence-based decision-making challenging, and a clear and current overview of all the evidence is required. This review is a network meta-analysis (NMA) which assesses the probability of complete ulcer healing associated with alternative dressings and topical agents.

OBJECTIVES

To assess the effects of (1) dressings and (2) topical agents for healing venous leg ulcers in any care setting and to rank treatments in order of effectiveness, with assessment of uncertainty and evidence quality.

SEARCH METHODS

In March 2017 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also scanned reference lists of relevant included studies as well as reviews, meta-analyses, guidelines and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting. We updated this search in March 2018; as a result several studies are awaiting classification.

SELECTION CRITERIA

We included published or unpublished randomised controlled trials (RCTs) that enrolled adults with venous leg ulcers and compared the effects of at least one of the following interventions with any other intervention in the treatment of venous leg ulcers: any dressing, or any topical agent applied directly to an open venous leg ulcer and left in situ. We excluded from this review dressings attached to external devices such as negative pressure wound therapies, skin grafts, growth factors and other biological agents, larval therapy and treatments such as laser, heat or ultrasound. Studies were required to report complete wound healing to be eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment and data extraction. We conducted this NMA using frequentist meta-regression methods for the efficacy outcome; the probability of complete healing. We assumed that treatment effects were similar within dressings classes (e.g. hydrocolloid, foam). We present estimates of effect with their 95% confidence intervals (CIs) for individual treatments focusing on comparisons with widely used dressing classes, and we report ranking probabilities for each intervention (probability of being the best, second best, etc treatment). We assessed the certainty (quality) of the body of evidence using GRADE for each network comparison and for the network as whole.

MAIN RESULTS

We included 78 RCTs (7014 participants) in this review. Of these, 59 studies (5156 participants, 25 different interventions) were included in the NMA; resulting in 40 direct contrasts which informed 300 mixed-treatment contrasts.The evidence for the network as a whole was of low certainty. This judgement was based on the sparsity of the network leading to imprecision and the general high risk of bias in the included studies. Sensitivity analyses also demonstrated instability in key aspects of the network and results are reported for the extended sensitivity analysis. Evidence for individual contrasts was mainly judged to be low or very low certainty.The uncertainty was perpetuated when the results were considered by ranking the treatments in terms of the probability that they were the most effective for ulcer healing, with many treatments having similar, low, probabilities of being the best treatment. The two most highly-ranked treatments both had more than 50% probability of being the best (sucralfate and silver dressings). However, the data for sucralfate was from one small study, which means that this finding should be interpreted with caution. When exploring the data for silver and sucralfate compared with widely-used dressing classes, there was some evidence that silver dressings may increase the probability of venous leg ulcer healing, compared with nonadherent dressings: RR 2.43, 95% CI 1.58 to 3.74 (moderate-certainty evidence in the context of a low-certainty network). For all other combinations of these five interventions it was unclear whether the intervention increased the probability of healing; in each case this was low- or very low-certainty evidence as a consequence of one or more of imprecision, risk of bias and inconsistency.

AUTHORS' CONCLUSIONS

More research is needed to determine whether particular dressings or topical agents improve the probability of healing of venous leg ulcers. However, the NMA is uninformative regarding which interventions might best be included in a large trial, largely because of the low certainty of the whole network and of individual comparisons.The results of this NMA focus exclusively on complete healing; whilst this is of key importance to people living with venous leg ulcers, clinicians may wish to take into account other patient-important outcomes and factors such as patient preference and cost.

A Double-Blind, Placebo-Controlled Randomized Evaluation of the Effect of Low-Level Laser Therapy on Venous Leg Ulcers

This study aimed to determine the effect of low-level laser therapy (LLLT) on chronic venous leg ulcers (VLUs). A double-blinded prospective randomized controlled trial was conducted to compare incidence of complete wound closure, ulcer size and pain reduction in patients randomized to 24 treatments of placebo or LLLT (635 nm) over 12 weeks. Patients presented with a 6-week history of VLUs ranging in size from 5 to 20 cm2. Venous origin was confirmed by Doppler ultrasound and an ankle brachial index of 0.8 or greater. Of 24 patients, 23% of the test group (n = 13) and 18% of placebo group (n = 11) achieved complete wound closure. At 12 weeks, patients in test and placebo groups had a mean surface area reduction of 6.26 cm2 ( P < .0001) and 6.72 cm2 ( P < .005), respectively, and a mean pain score decrease of 43.54 points ( P < .0001) and 25.73 points ( P = .002) respectively. Differences between groups was not statistically significant for wound closure ( P = 1.0) or ulcer size ( P = .80). Mean ulcer pain was significantly reduced from initiation of treatment compared with 4 weeks’ follow-up after 12 weeks with LLLT ( P < .01). Within the limitations of the study, LLLT may not have early effects as an adjunctive therapy to wound healing of VLUs, but LLLT may have delayed effects on VLU healing and associated pain, which requires further study.

Collagen production in diabetic wounded fibroblasts in response to low-intensity laser irradiation at 660 nm

BACKGROUND

Collagen type I (Col-I) is a major component of the extracellular matrix and is important in wound healing processes. Several studies have shown that low-intensity laser irradiation (LILI) biostimulates Col-I synthesis both in vitro and in vivo. This study aimed to determine if LILI affects collagen production and related cellular responses in an in vitro diabetic wounded fibroblast model.

MATERIALS AND METHODS

This study was performed on isolated human skin fibroblasts. Different cell models (normal and diabetic wounded) were used. Cells were irradiated with 5 J/cm(2) at a wavelength of 660 nm and incubated for 48 or 72 h. Nonirradiated cells (0 J/cm(2)) were used as controls. Cellular viability (Trypan blue exclusion test), morphology (bright-field microscopy), proliferation [VisionBlue™ quick cell proliferation assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay], and Col-I (enzyme-linked immunoabsorbent assay) were assessed.

RESULTS

Diabetic wounded cells irradiated with 5 J/cm(2) at 660 nm showed a significant increase in cell migration, viability, proliferation, and collagen content.

CONCLUSIONS

This study shows that LILI stimulates Col-I synthesis in diabetic wound healing in vitro at 660 nm.

Low-intensity laser irradiation stimulates wound healing in diabetic wounded fibroblast cells (WS1)

BACKGROUND

Patients with diabetes suffer from slow-to-heal wounds, which often necessitate amputation. Low-intensity laser irradiation (LILI) has been shown to reduce the healing time in such patients. This study aimed to determine the effect of different wavelengths of LILI on cellular migration, viability, and proliferation in a wounded diabetic cell model.

METHODS

Diabetic wounded and unwounded human skin fibroblast cells (WS1) were irradiated at 632.8, 830, or 1,064 nm with 5 J/cm(2). Cellular morphology and migration were determined microscopically, while cellular viability was determined by ATP luminescence, and proliferation was determined by basic fibroblast growth factor expression and alkaline phosphatase activity.

RESULTS

Diabetic wounded cells irradiated at 1,064 nm showed a lesser degree of migration, viability, and proliferation compared to cells irradiated at 632.8 or 830 nm. Cells irradiated at 632.8 nm showed a higher degree of haptotaxis and migration as well as ATP luminescence compared to cells irradiated at 830 nm.

CONCLUSIONS

This study showed that LILI of diabetic wounded cells in the visible range (632.8 nm) was more beneficial to wound healing than irradiating the same cells to wavelengths in the infrared range. Cells irradiated at a longer wavelength of 1,064 nm performed worse.

The light revival: does phototherapy promote wound healing? A review

BACKGROUND

Throughout history, light has been recognised as a potential source of healing. The introduction of lasers made it possible to modify and control light for optimum therapeutic use.

AIM

This paper reviews recent clinical trials that test phototherapy on human models in order to assess the value of phototherapy in routine wound care.

METHOD

A literature search was undertaken using a variety of sources including online databases.

RESULTS

The results of numerous in vitro and animal investigations suggest that phototherapy may stimulate cell activity and promote tissue repair. Reports of human clinical trials are relatively few. There is inconsistency of selected treatment parameters amongst studies testing the effect of phototherapy on wound healing. Clinical trials using human models do not provide sufficient evidence to establish the usefulness of phototherapy as an effective tool in wound care regimes.

CONCLUSION

Further well designed research trials are required to determine the true value of phototherapy in routine wound care.

Red Light Phototherapy Alone Is Effective for Acne Vulgaris: Randomized, Single-Blinded Clinical Trial

BACKGROUND

Recently, a demand for safe and effective treatment of acne has been increasing. Although visible light has attracted attention as a new option, the effect of red light alone has not yet been evaluated.

OBJECTIVES

The objective was to assess the efficacy of red light phototherapy with a portable device in acne vulgaris.

METHODS

Twenty-eight volunteers with mild to moderate acne were treated with portable red light-emitting devices in this split-face randomized trial. The right or left side of the face was randomized to treatment side and phototherapy was performed for 15 minutes twice a day for 8 weeks. Clinical photographs, lesion counts, and a visual analog scale (VAS) were used to assess each side of the face at baseline and Weeks 1, 2, 4, and 8, and a split-face comparison was performed.

RESULTS

The percent improvement in noninflammatory and inflammatory lesion counts of the treated side was significant compared to the control side (p<.005). VAS decreased from 3.9 to 1.9 on the treatment side and the difference between the treatment and control sides was significant at Week 8 (p<.005).

CONCLUSIONS

This study shows that red light phototherapy alone can be a new therapeutic option for acne vulgaris.