What is better in TRAM flap survival: LLLT single or multi-irradiation?

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.

Photobiomodulation effect in tumoral necrosis factor-alpha(TNF-α) on the viability of random skin flap in rats

The aim of this study was to investigate the effect of red laser (660 nm) photobiomodulation (PBM) with different energies on tumor necrosis factor-alpha(TNF-α) expression for random skin flap viability in rats. Twenty-four Wistar rats were divided into three groups: sham group (SG), PBM laser group with an energy dose of 0.29 J (0.29G), and PBM laser group with an energy dose of 7.30 J (7.30G). A cranially based dorsal skin flap measuring 10 × 4 cm was raised and a plastic barrier was placed between the flap and its bed. PBM was applied in 3 timepoints: in the immediate postoperative period, in the 1^st and in the 2^nd postoperative days; the animals were euthanized on the 7^th postoperative day. The assessments included: TNF-α expression of 3 different flap areas (proximal, medial and distal), by immunohistochemistry; percentage of skin flap necrosis area, by the paper template method. The statistical analysis was performed through the Kruskal-Wallis and Mann-Whitney tests, the level of significance adopted was 5% (p < 0.05). TNF-α expression was significantly lower for 7.30G in the proximal area, reduced for SG in the medial point, and larger for 7.30G in the distal area. The percentage of flap necrosis area was significantly reduced for 7.30G. Higher energy doses are more efficacious than lower energy doses for modulating TNF-α expression. PBM with an energy dose of 7.30 J was effective in reducing the expression of TNF-α and increase skin flap viability.

Viability of transverse rectus abdominis musculocutaneous flap treated with photobiomodulation and therapeutic ultrasound: an experimental model

Report the effects of photobiomodulation (PBM) and therapeutic ultrasound (TUS) on the viability of TRAM in mice.

MATERIALS AND METHODS

Fifty-five mice Swiss were subjected to treatment for 5 days. Group 1, treatment was performed with the agents switched off. Groups 2 to 5 were treated with different wavelengths 660 and 830 nanometers (nm) and groups 6 to 11 with TUS of 1 and 3 MHz frequency. Macrometric analyses were performed using a specific camera and analyzed by the ImageJ® software. Thermographic analyses were performed with the Flir C2 and analyzed using the FLIR Tools software.

RESULTS

Group 9 obtained 95% of viable area on the 3rd day and 85% on the 5th day, showing the effectiveness of the TUS in the flap viability. Regarding skin temperature, there was a difference only in the immediate postoperative period in group 1, which had a lower temperature than the other groups.

CONCLUSIONS

TUS demonstrated greater efficiency in maintaining the viability of TRAM. PBM 830 nm also demonstrated good results in the viability of TRAM.

Comparison of photobiomodulation in the treatment of skin injury with an open wound in mice

This study aimed to investigate the effects of photobiomodulation at a wavelength of 660 and 830 nm at different numbers of application points in the healing of open wounds in mice. In total, 120 mice were divided into 10 groups. The animals were submitted to cutaneous lesion of the open wound type (1.5 × 1.5 cm). Photobiomodulation at a wavelength of 660 and 830 nm and total energy of 3.6 J were used, applied at 1, 4, 5, and 9 points, for 14 days. The animals were subjected to analysis of the lesion area, skin temperature, and histological analysis. Macroscopic analysis results showed a difference (p < 0.05) between the irradiated groups and the sham group at 14 days PO. There was no statistical difference in skin temperature. Histological analysis findings showed better results for the epidermis thickness. Regarding the number of blood vessels, a difference was found between the 1- and 5-point 830-nm photobiomodulation groups and between the 4-point 660-nm group and the naive group. A significant difference in the number of fibroblasts was observed between the 830- and 660-nm photobiomodulation groups and the naive and sham groups. When comparing photobiomodulation wavelength, the 830-nm groups were more effective, and we emphasize the groups irradiated at 5 points, which showed an improvement in macroscopic analysis and epidermis thickness, an increase in the number of vessels, and a lower number of fibroblasts on the 14th day after skin injury.

Effects of High-Voltage Electrical Stimulation in Improving the Viability of Musculocutaneous Flaps in Rats

BACKGROUND

The musculocutaneous flap of the transverse rectus abdominis muscle is a technique used for breast reconstruction, and one of the complications of this procedure is tissue necrosis. The objective of the study is to determine the effect of high-voltage electrical stimulation (HVES) in the transverse rectus abdominis muscle flap in rats.

METHODS

Fourteen rats underwent surgery for obtaining the flap. The rats were distributed into 2 homogeneous groups: group 1 underwent both surgery and the use of HVES, whereas group 2 underwent just the surgery (control). Electrical stimulation was applied immediately after surgery and for 2 consecutive days. The percentage of necrotic area was analyzed using the Image J software, and blood flow was assessed by infrared thermography in different regions of the flap, divided into 4 zones according to the proximity of the pedicle of the inferior epigastric artery.

RESULTS

The results were analyzed using a Student t test, where group 1 experienced a necrotic area of 26.2%, and group 2 had an area of 54.5%. Regarding the temperature, the 2 groups showed increase in the minimum and maximum temperature on the fourth postoperative day.

CONCLUSION

The HVES appeared to have a positive influence on the viability of the flap.

Laser photobiomodulation (830 and 660 nm) in mast cells, VEGF, FGF, and CD34 of the musculocutaneous flap in rats submitted to nicotine

The aim of this study was to investigate the effect of laser photobiomodulation (PBM) on the viability of the transverse rectus abdominis musculocutaneous (TRAM) flap in rats subjected to the action of nicotine. We evaluated 60 albino Wistar rats, divided into six groups of ten animals. Group 1 (saline) underwent the surgical technique to obtain a TRAM flap; group 2 (laser 830 nm) underwent the surgical technique and was irradiated with a laser 830 nm; group 3 (laser 660 nm) underwent the surgical technique and was irradiated with a laser 660 nm; group 4 was treated with nicotine subcutaneously (2 mg/kg/2×/day/4 weeks) and underwent surgery; group 5 (nicotine + laser 830 nm) was exposed to nicotine, underwent the surgical technique, and was irradiated with a laser 830 nm; group 6 (nicotine + laser 660 nm) was exposed to nicotine, underwent the surgical technique, and was irradiated with a laser 660 nm. The application of PBM occurred immediately after surgery and on the two following days. The percentage of necrosis was assessed using the AxioVision® software. The number of mast cells (toluidine blue staining) was evaluated, and immunohistochemistry was performed to detect vascular endothelial growth factor expression (anti-VEGF-A), fibroblasts (anti-basic FGF), and neoformed vessels (anti-CD34). PBM with a wavelength of 830 nm increased the viability of the TRAM flap, with a smaller area of necrosis, increased number of mast cells, and higher expression of VEGF and CD34. PBM increases the viability of musculocutaneous flaps treated with to nicotine.

Low level laser therapy reduces acute lung inflammation without impairing lung function

Acute lung injury is a condition characterized by exacerbate inflammatory reaction in distal airways and lung dysfunction. Here we investigate the treatment of acute lung injury (ALI) by low level laser therapy (LLLT), an effective therapy used for the treatment of patients with inflammatory disorders or traumatic injuries, due to its ability to reduce inflammation and promote tissue regeneration. However, studies in internal viscera remains unclear. C57BL/6 mice were treated with intratracheal lipopolysaccharide (LPS) (5 mg/kg) or phosphate buffer saline (PBS). Six hours after instillation, two groups were irradiated with laser at 660 nm and radiant exposure of 10 J/cm² . Intratracheal LPS inoculation induced a marked increase in the number of inflammatory cells in perivascular and alveolar spaces. There was also an increase in the expression and secretion of cytokines (TNF-α, IL-1β, IL-6,) and chemokine (MCP-1). The LLLT application induced a significant decrease in both inflammatory cells influx and inflammatory mediators secretion. These effects did not affect lung mechanical properties, since no change was observed in tissue resistance or elastance. In conclusion LLLT is able to reduce inflammatory reaction in lungs exposed to LPS without affecting the pulmonary function and recovery.

Low-level laser (light) therapy (LLLT) for treatment of hair loss

OBJECTIVE

Alopecia is a common disorder affecting more than half of the population worldwide. Androgenetic alopecia, the most common type, affects 50% of males over the age of 40 and 75% of females over 65. Only two drugs have been approved so far (minoxidil and finasteride) and hair transplant is the other treatment alternative. This review surveys the evidence for low-level laser therapy (LLLT) applied to the scalp as a treatment for hair loss and discusses possible mechanisms of actions.

METHODS AND MATERIALS

Searches of PubMed and Google Scholar were carried out using keywords alopecia, hair loss, LLLT, photobiomodulation.

RESULTS

Studies have shown that LLLT stimulated hair growth in mice subjected to chemotherapy-induced alopecia and also in alopecia areata. Controlled clinical trials demonstrated that LLLT stimulated hair growth in both men and women. Among various mechanisms, the main mechanism is hypothesized to be stimulation of epidermal stem cells in the hair follicle bulge and shifting the follicles into anagen phase.

CONCLUSION

LLLT for hair growth in both men and women appears to be both safe and effective. The optimum wavelength, coherence and dosimetric parameters remain to be determined.

Low-level laser therapy for fat layer reduction: a comprehensive review

BACKGROUND AND OBJECTIVE

Low-level laser (light) therapy (LLLT) is a noninvasive, nonthermal approach to disorders requiring reduction of pain and inflammation and stimulation of healing and tissue regeneration. Within the last decade, LLLT started being investigated as an adjuvant to liposuction, for noninvasive body contouring, reduction of cellulite, and improvement of blood lipid profile. LLLT may also aid autologous fat transfer procedures by enhancing the viability of adipocytes. However the underlying mechanism of actions for such effects still seems to be unclear. It is important, therefore, to understand the potential efficacy and proposed mechanism of actions of this new procedure for fat reduction.

MATERIALS AND METHODS

A review of the literature associated with applications of LLLT related to fat layer reduction was performed to evaluate the findings from pre-clinical and clinical studies with respect to the mechanism of action, efficacy, and safety.

RESULTS

The studies as of today suggest that LLLT has a potential to be used in fat and cellulite reduction as well as in improvement of blood lipid profile without any significant side effects. One of the main proposed mechanism of actions is based upon production of transient pores in adipocytes, allowing lipids to leak out. Another is through activation of the complement cascade which could cause induction of adipocyte apoptosis and subsequent release of lipids.

CONCLUSION

Although the present studies have demonstrated safety and efficacy of LLLT in fat layer reduction, studies demonstrating the efficacy of LLLT as a stand-alone procedure are still inadequate. Moreover, further studies are necessary to identify the mechanism of action.