Preemptive treatment with photobiomodulation therapy in skin flap viability

Photobiomodulation in promoting increased Skin Flap Viability: a systematic review of animal studies

Necrosis is common in skin flap surgeries. Photobiomodulation, a noninvasive and effective technique, holds the potential to enhance microcirculation and neovascularization. As such, it has emerged as a viable approach for mitigating the occurrence of skin flap necrosis. The aim of this systematic review was to examine the scientific literature considering the use of photobiomodulation to increase skin-flap viability. The preferred reporting items for systematic reviews and meta-analyses (PRISMA), was used to conducted systematic literature search in the databases PubMed, SCOPUS, Elsevier and, Scielo on June 2023. Included studies investigated skin-flap necrosis employing PBMT irradiation as a treatment and, at least one quantitative measure of skin-flap necrosis in any animal model. Twenty-five studies were selected from 54 original articles that addressed PBMT with low-level laser (LLL) or light-emitting diode (LED) in agreement with the qualifying requirements. Laser parameters varied markedly across studies. In the selected studies, the low-level laser in the visible red spectrum was the most frequently utilized PBMT, although the LED PBMT showed a similar improvement in skin-flap necrosis. Ninety percent of the studies assessing the outcomes of the effects of PBMT reported smaller areas of necrosis in skin flap. Studies have consistently demonstrated the ability of PBMT to improve skin flap viability in animal models. Evidence suggests that PBMT, through enhancing angiogenesis, vascular density, mast cells, and VEGF, is an effective therapy for decrease necrotic tissue in skin flap surgery.

Edaravone promotes viability of random skin flaps via activating PI3K/Akt/mTOR signalling pathway-mediated enhancement of autophagy

Random skin flap transplantation is a commonly used technique. However, ischemia and ischemia-reperfusion injury always impair its therapeutic effectiveness through acclerating oxidative stress, apoptosis and suppressing angiogenesis. To survive, cells rely on mediating autophagy, DNA repair, immunoregulation to resist these cellular injuries. Thus, mediating autophagy may affect the survival of random skin flaps. The edaravone (EDA), a oxygen radicals scavenger, also possesses autophagy mediator potential, we investigated the effects of EDA on skin flap survival and its autophagy-related mechanisms. In vivo, mice were administered EDA or saline intraperitoneally for 7 days postoperatively. We found that EDA ameliorated the viability of random skin flaps, promoted autophagy and angiogenesis, attenuated apoptosis and oxidative stress. In vitro, mouse umbilical vascular endothelial cells (MUVECs) were administered EDA or 3-methyladenine (3-MA, an autophagy inhibitor) or rapacymin (Rapa, an autophagy activator) at the beginning of oxygen glucose deprivation (OGD). We found that EDA promoted cell viability, activated autophagy, enhanced angiogenesis, alleviated apoptosis and oxidative stress. On one hand, 3-MA reversed the effects of EDA on cell viability, oxidative stress and apoptosis via inhibiting autophagy. On the other hand, Rapa had the similar effects of EDA. Furthermore, EDA-induced autophagy was mediated through downregulating PI3K/Akt/mTOR signalling pathway. The findings showed that EDA ameliorated viability of random skin flaps by promoting angiogenesis, suppressing oxidative stress and apoptosis, which may be mediated by autophagic activation through downregulating PI3K/AKT/mTOR signalling pathway.

Activation of aldehyde dehydrogenase-2 improves ischemic random skin flap survival in rats

Objective

Random skin flaps have many applications in plastic and reconstructive surgeries. However, distal flap necrosis restricts wider clinical utility. Mitophagy, a vital form of autophagy for damaged mitochondria, is excessively activated in flap ischemia/reperfusion (I/R) injury, thus inducing cell death. Aldehyde dehydrogenase-2 (ALDH2), an allosteric tetrameric enzyme, plays an important role in regulating mitophagy. We explored whether ALDH2 activated by N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1) could reduce the risk of ischemic random skin flap necrosis, and the possible mechanism of action.

Methods

Modified McFarlane flap models were established in 36 male Sprague-Dawley rats assigned randomly to three groups: a low-dose Alda-1 group (10 mg/kg/day), a high-dose Alda-1 group (20 mg/kg/day) and a control group. The percentage surviving skin flap area, neutrophil density and microvessel density (MVD) were evaluated on day 7. Oxidative stress was quantitated by measuring the superoxide dismutase (SOD) and malondialdehyde (MDA) levels. Blood perfusion and skin flap angiogenesis were assessed via laser Doppler flow imaging and lead oxide-gelatin angiography, respectively. The expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α), vascular endothelial growth factor (VEGF), ALDH2, PTEN-induced kinase 1 (PINK1), and E3 ubiquitin ligase (Parkin) were immunohistochemically detected. Indicators of mitophagy such as Beclin-1, p62, and microtubule-associated protein light chain 3 (LC3) were evaluated by immunofluorescence.

Results

Alda-1 significantly enhanced the survival area of random skin flaps. The SOD activity increased and the MDA level decreased, suggesting that Alda-1 reduced oxidative stress. ALDH2 was upregulated, and mitophagy-related proteins (PINK1, Parkin, Beclin-1, p62, and LC3) were downregulated, indicating that ALDH2 inhibited mitophagy through the PINK1/Parkin signaling pathway. Treatment with Alda-1 reduced neutrophil infiltration and expressions of inflammatory cytokines. Alda-1 significantly upregulated VEGF expression, increased the MVD, promoted angiogenesis, and enhanced blood perfusion.

Conclusion

ALDH2 activation can effectively enhance random skin flap viability via inhibiting PINK1/Parkin-dependent mitophagy. Moreover, enhancement of ALDH2 activity also exerts anti-inflammatory and angiogenic properties.

The Combined Effects of a Methacrylate Powder Dressing (Altrazeal Powder) and Photobiomodulation Therapy on the Healing of a Severe Diabetic Foot Ulcer in a Diabetic Patient: A Case Report

Weakened wound healing is a popular, severe complication of patients with diabetes which poses a risk for foot infection and amputation. Researchers have searched for new treatments for treating diabetic foot ulcers (DFUs) in recent years. In this case report, for the first time, we applied photobiomodulation therapy (PBMT) and Altrazeal powder together to treat a severe case of DFU in a 47-year-old woman who was suffering from type 1 diabetes. Along with the progress of combination therapy, we observed that the ulcer area was significantly reduced, and the wound healed within 16 weeks. Furthermore, dermatitis and purulent secretion were treated, and the pain was reduced. This reported case study indicated the beneficial effect of the combination of PBMT and Altrazeal powder for the healing of a severe DFU in a patient with type one diabetes. The combined application of PBMT plus Altrazeal powder demonstrated an additive effect. Further clinical trials in the clinical setting are suggested to validate the results further. Besides, more studies in preclinical models are suggested to find the mechanism of the action of combination therapy.

Photobiomodulation therapy combined with radiotherapy in the treatment of triple-negative breast cancer-bearing mice

This work investigated the effect of photobiomodulation therapy (PBM) combined with radiotherapy (RT) on triple-negative breast cancer (TNBC)-bearing mice. Female BALB/c mice received 4 T1 cells into a mammary fat pad. Local RT was performed with a total dose of 60 Gy divided into 4 consecutive sessions of 15 Gy. For PBM, a red laser was used in three different protocols: i-) single exposure delivering 150 J.cm^-2 (24 h after the last RT session), and ii-) radiant exposure of 150 J.cm^-2 or iii-) fractionated radiant exposure of 37.5 J.cm^-2 (after each RT session). Tumor volume, complete blood cell count, clinical condition, metastasis, and survival of animals were monitored during 3 weeks post-RT. Our results demonstrated that regardless of the protocol, PBM arrested the tumor growth, improved the clinical condition, and prevented hemolytic anemia. Besides, although PBM groups have exhibited a high neutrophil:lymphocyte ratio (NLR), they decreased the number of lung metastases and enhanced mouse survival. Worthy of note, PBM should be used along with the RT sessions in higher radiant exposures, since PBM at 150 J.cm^-2 per session significantly extended the survival rate. Together, these data suggest PBM could be a potential ally to RT to fight TNBC.

Postconditioning With Red-Blue Light Therapy Improves Survival of Random Skin Flaps in a Rat Model

BACKGROUND

Random skin flap ischemic necrosis is a serious challenge in reconstructive surgery. Photobiomodulation is a noninvasive effective technique to improve microcirculation and neovascularization. Photobiomodulation with red or blue light has been separately proven to partially prevent skin flap necrosis, but the synergistic effect of red and blue light not been elucidated. Our experiment evaluated the impact of postconditioning with red-blue light therapy on the viability of random flaps.

METHODS

Thirty Sprague-Dawley male rats (male, 12 weeks) with a cranially based random pattern skin flap (3 × 8 cm) were divided into 3 groups: control group, red light group, and red-blue light group. On postoperative day 7, flap survival was observed and recorded using transparent graph paper, flaps were obtained and stained with hematoxylin and eosin, and microvessel density was measured. Micro-computed tomography was used to measure vascular volume and vascular length. On days 0, 3, and 7 after surgery, blood flow was measured by laser Doppler. To investigate the underlying mechanisms, the amount of nitric oxide (NO) metabolites in the flap tissue was assessed on days 3, 5, and 7 after surgery.

RESULTS

The mean percentage of skin flap survival was 59 ± 10% for the control group, 69 ± 7% for the red light group, and 79 ± 9% for the red-blue light group (P < 0.01). The microvessel density was 12.3 ± 1.2/mm2 for the control group, 31.3 ± 1.3/mm2 for the red light group, and 36.5 ± 1.4/mm2 for the red-blue light group (P < 0.01). Both vascular volume and total length in the red-blue light group showed significantly increased compared with the red light and control group (P < 0.01). Blood flow in the red-blue light treated flap showed significantly increased at postsurgery days 3 and 7 compared with the red light and control group (P < 0.01). The level of the NO metabolites was significantly increased in flap tissues belonging to the red-blue light group compared with the other 2 groups (P < 0.01).

CONCLUSIONS

This study showed that postconditioning with red-blue light therapy can enhance the survival of random skin flap by improving angiogenesis and NO releasing.

Photobiomodulation therapy was more effective than photobiomodulation plus arginine on accelerating wound healing in an animal model of delayed healing wound

The combined and individual influences of photobiomodulation therapy (PBMT) and arginine on wound strength, stereological parameters, and gene expressions of some related growth factors in ischemic and delayed healing wounds in rats were analyzed. We divided 108 rats into six groups: control, lower energy density (LOW)-PBMT, 2% arginine ointment (Arg 2%), LOW-PBMT + Arg 2%, high energy density (HIGH)-PBMT, and HIGH-PBMT + Arg 2%. First, we generated an ischemic and delayed healing wound model in each rat. We examined wound strength, stereological parameters, and gene expressions of basic fibroblast growth factor (bFGF), vascular endothelial growth factor A (VEGF-A), and stromal cell-derived factor 1 (SDF-1) by quantitative real-time polymerase chain reaction (qRT-PCR). PBMT alone and PBMT + Arg 2% considerably increased wound strength compared to the control and Arg 2% groups during the inflammatory and proliferative steps of wound healing (p < 0.05). In these steps, PBMT alone significantly induced an anti-inflammatory effect and increased fibroblast counts; Arg 2% alone induced an inflammatory response (p < 0.05). Concurrently, PBMT and PBMT + Arg 2% significantly increased keratinocyte counts and volume of the new dermis (p < 0.05). At the remodeling step, the Arg 2% groups had significantly better wound strength than the other groups (p < 0.05). In this step, PBMT and PBMT + Arg 2% significantly decreased inflammation, and increased fibroblast counts, vascular length, and the volume of new epidermis and dermis compared to the control and Arg 2% groups (p < 0.05). In all cases of gene analysis, there were statistically better results in the PBMT and PBMT + Arg 2% groups compared with the Arg 2% and control groups (p < 0.05). The anti-inflammatory and repairing effects of PBMT on an ischemic and delayed healing wound model in rats were shown by significant improvements in wound strength, stereological parameters, and gene expressions of bFGF, VEGF-A, and SDF-1α.

Red and near-infrared light evokes Ca2+ influx, endoplasmic reticulum release and membrane depolarization in neurons and cancer cells

Low level light therapy uses light of specific wavelengths in red and near-infrared spectral range to treat various pathological conditions. This light is able to modulate biochemical cascade reactions in cells that can have important health implications. In this study, the effect of low intensity light at 650, 808 and 1064 nm on neurons and two types of cancer cells (neuroblastoma and HeLa) is reported, with focus on the photoinduced change of intracellular level of Ca²⁺ ions and corresponding signaling pathways. The obtained results show that 650 and 808 nm light promotes intracellular Ca²⁺ elevation regardless of cell type, but with different dynamics due to the specificities of Ca²⁺ regulation in neurons and cancer cells. Two origins responsible for Ca²⁺ elevation are determined to be: influx of exogenous Ca²⁺ ions into cells and Ca²⁺ release from endoplasmic reticulum. Our investigation of the related cellular processes shows that light-induced membrane depolarization is distinctly involved in the mechanism of Ca²⁺ influx. Ca²⁺ release from endoplasmic reticulum activated by reactive oxygen species generation is considered as a possible light-dependent signaling pathway. In contrast to the irradiation with 650 and 808 nm light, no effects are observed under 1064 nm irradiation. We believe that the obtained insights are of high significance and can be useful for the development of drug-free phototherapy.

Effect of photobiomodulation therapy on radiodermatitis in a mouse model: an experimental animal study

This study aimed to evaluate the effect of photobiomodulation (PBM) for prevention of radiodermatitis in an irradiated mouse model and compare the efficacy of PBM using 633- or 830-nm wavelengths. Irradiated mice were randomly distributed into three groups: A (633 nm), B (830 nm), and C (without PBM). On post-irradiation days 7 and 21, we compared acute damage and recovery in treated skin samples to non-irradiated skin using H&E, Masson's trichrome, anti-CD45 and PCNA immunohistochemistry, and a TUNEL assay. Grade 3 radiodermatitis was evident only in group C. Compared with that in group C, the skin in groups A and B had significantly less epidermal hyperplasia, inflammatory cell infiltration, and thinner dermis on day 7 and less inflammatory cell infiltration, fewer apoptotic cells, and thinner dermis on day 21. However, there was no significant difference between groups A and B. This study indicates PBM could prevent severe radiodermatitis by reducing epidermal and dermal damage, inflammation, and apoptosis. There was no difference in PBM efficacy between the 633- and 830-nm wavelengths.