Applications of mesenchymal stem cell-exosome components in wound infection healing: new insights

The healing process at a wound is made up of many types of cells, growth factors, the extracellular matrix, nerves and blood vessels all interacting with each other in complex and changing ways. Microbial colonization and proliferation are possible at the place of injury, which makes infection more likely. Because of this, any cut has a chance of getting an infection. Researchers have found that wound infections make patients more upset and cost the healthcare system a lot of money. Surgical site infections happen a lot to people who have recently had surgery. This study shows that such surgical infection is linked to a high rate of illness and death. This is shown by the fact that 25% of patients get serious sepsis and need to be transferred to an intensive care unit. In both animal models and people, mesenchymal stem cells (MSCs) play an active role in all stages of wound healing and have positive effects. Exosomes are one of the main things MSCs release. They have effects that are similar to those of the parent MSCs. Various effector proteins, messenger RNA and microRNAs can be transported by extracellular vesicles to control the activity of target cells. This has a big impact on the healing process. These results suggest that using MSC-exosomes as a new type of cell-free therapy could be a better and safer option than whole cell therapy. This review is mostly about how to use parts of MSC-exosomes to help wound infections heal.

Diabetes in spotlight: current knowledge and perspectives of photobiomodulation utilization

Introduction

Diabetes is a global health concern characterized by chronic hyperglycemia resulting from insulinopenia and/or insulin resistance. The rising prevalence of diabetes and its associated complications (ulcers, periodontitis, healing of bone defect, neuropathy, retinopathy, cardiopathy and nephropathy) necessitate innovative therapeutic approaches. Photobiomodulation (PBM), involves exposing tissues and cells to low-energy light radiation, leading to biological effects, largely via mitochondrial activation.

Methods

This review evaluates preclinical and clinical studies exploring the potential of PBM in diabetes and its complications, as well all clinical trials, both planned and completed, available on ClinicalTrials database.

Results

This review highlights the variability in PBM parameters across studies, hindering consensus on optimal protocols. Standardization of treatment parameters and rigorous clinical trials are needed to unlock PBM's full therapeutic potential. 87 clinical trials were identified that investigated PBM in diabetes mellitus (with 5,837 patients planned to be treated with PBM). Clinical trials assessing PBM effects on diabetic neuropathy revealed pain reduction and potential quality of life improvement. Studies focusing on wound healing indicated encouraging results, with PBM enhancing angiogenesis, fibroblast proliferation, and collagen density. PBM's impact on diabetic retinopathy remains inconclusive however, requiring further investigation. In glycemic control, PBM exhibits positive effects on metabolic parameters, including glucose tolerance and insulin resistance.

Conclusion

Clinical studies have reported PBM-induced reductions in fasting and postprandial glycemia without an increased hypoglycemic risk. This impact of PBM may be related to its effects on the beta cells and islets in the pancreas. Notwithstanding challenges, PBM emerges as a promising adjunctive therapy for managing diabetic neuropathy, wound healing, and glycemic control. Further investigation into its impact on diabetic retinopathy and muscle recovery is warranted.

Fluorescent microscopy evaluation of diode laser effect on the penetration depth of turmeric (Curcuma longa) extract cream on skin tissues of Wistar rats

The study investigates the effect of diode laser exposure on curcumin's skin penetration, using turmeric extraction as a light-sensitive chemical and various laser light sources. It uses an in vivo skin analysis method on Wistar strain mice. The lasers are utilized at wavelengths of 403 nm, 523 nm, 661 nm, and 979 nm. The energy densities of the lasers are 20.566 J/cm2, 20.572 J/cm2, 21.162 J/cm2, and 21.298 J/cm2, which are comparable to one another. The experimental animals were divided into three groups: base cream (BC), turmeric extract cream (TEC), and the combination laser (L), BC, and TEC treatment group. Combination light source (LS) with cream (C) was performed with 8 combinations namely 523 nm ((L1 + BC) and (L1 + TEC)), 661 nm ((L2 + BC) and (L2 + TEC)), 403 nm ((L3 + BC) and (L3 + TEC)), and 979 nm ((L4 + BC) and (L4 + TEC)). The study involved applying four laser types to cream-covered and turmeric extract-coated rat skin, with samples scored for analysis. The study found that both base cream and curcumin cream had consistent pH values of 7-8, within the skin's range, and curcumin extract cream had lower viscosity. The results of the statistical analysis of Kruskal-Wallis showed a significant value (p < 0.05), which means that there are at least two different laser treatments. The results of the post hoc analysis with Mann-Whitney showed that there was no significant difference in the LS treatment with the addition of BC or TEC when compared to the BC or TEC treatment alone (p > 0.05), while the treatment using BC and TEC showed a significant difference (p < 0.05). Laser treatment affects the penetration of the turmeric extract cream into the rat skin tissue.

Photobiomodulation Facilitates Rat Cutaneous Wound Healing by Promoting Epidermal Stem Cells and Hair Follicle Stem Cells Proliferation

BACKGROUND

Cutaneous wound healing represents a common fundamental phenomenon requiring the participation of cells of distinct types and a major concern for the public. Evidence has confirmed that photobiomodulation (PBM) using near-infrared (NIR) can promote wound healing, but the  cells involved and the precise molecular mechanisms remain elusive.

METHODS

Full-thickness skin defects with a diameter of 1.0 cm were made on the back of rats and randomly divided into the control group, 10 J, 15 J, and 30 J groups. The wound healing rate at days 4, 8, and 12 postoperatively was measured. HE and Masson staining was conducted to reveal the histological characteristics. Immunofluorescence staining was performed to label the epidermal stem cells (ESCs) and hair follicle stem cells (HFSCs). Western blot was performed to detect the expressions of proteins associated with ESCs and HFSCs. Cutaneous wound tissues were collected for RNA sequencing. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes analysis was performed, and the hub genes were identified using CytoHubba and validated by qRT-PCR.

RESULTS

PBM can promote reepithelialization, extracellular matrix deposition, and wound healing, increase the number of KRT14+/PCNA+ ESCs and KRT15+/PCNA+ HFSCs, and upregulate the protein expression of P63, Krt14, and PCNA. Three hundred and sixty-six differentially expressed genes (DEGs) and 7 hub genes including Sox9, Krt5, Epcam, Cdh1, Cdh3, Dsp, and Pkp3 were identified. These DEGs are enriched in skin development, cell junction, and cadherin binding involved in cell-cell adhesion etc., while these hub genes are related to skin derived stem cells and cell adhesion.

CONCLUSION

PBM accelerates wound healing by enhancing reepithelialization through promoting ESCs and HFSCs proliferation and elevating the expression of genes associated with stem cells and cell adhesion. This may provide a valuable alternative strategy to promote wound healing and reepithelialization by modulating the proliferation of skin derived stem cells and regulating genes related to cell adhesion.

The effect of photomodulation on fibroblast growth factor and the Ras/MAPK signalling pathway: a review

Objective:

Current therapies and technologies used to treat hard-to-heal diabetic wounds are limited to a 50% healing rate. The rise in the percentage of lower limb non-traumatic amputations in patients with diabetes has caused an increased demand for alternative, effective and safe treatment modalities. Photobiomodulation therapy (PBMT) utilises light to induce physiological changes and provide therapeutic benefits and has been shown to increase the healing of hard-to-heal wounds through the release of growth factors. The aim of this narrative review is to investigate the effect of photobiomodulation (PBM) on fibroblast growth factor (FGF) and the role of the Ras/MAPK signalling pathway in diabetic wound healing.

Method:

Relevant journal articles were obtained through PubMed and Google Scholar.

Results:

Experimental and clinical findings from the review show that PBM can stimulate the release of growth factors, including FGF, an essential cytokine in wound healing, and one which is present at lower concentrations in diabetic wounds. There is also activation of the Ras/MAPK signalling pathway.

Conclusion:

One mechanism through which healing may be stimulated by PBM is via the FGF-Ras/MAPK signalling pathway, although strong evidence under hyperglycaemic conditions is lacking.

Photobiomodulation-Activated Latent Transforming Growth Factor-β1: A Critical Clinical Therapeutic Pathway and an Endogenous Optogenetic Tool for Discovery

Objective: The central role of the TGF-β pathway in embryonic development, immune responses, tissue healing, and malignancies is well established. Prior attempts with small molecules, peptides, and regulatory RNAs have failed mainly due to off-target effects in clinical studies. This review outlines the evidence for selectively activating the endogenous, latent transforming growth factor (TGF)-β1 with photobiomodulation (PBM) treatments. Background: Light treatments play a central role in current-directed energy therapeutics in medicine. Therapeutic use of low-dose light treatments has been noted since the 1960s. However, the breadth of treatments and inconsistencies with clinical outcomes have led to much skepticism. This can be primarily attributed to a lack of understanding of the fundamental light-tissue interactions and optimization of clinical treatment protocols. Methods: Recent advances in molecular mechanisms and improved biophotonic device technologies have led to a resurgence of interest in this field. Results: Over the past two decades, our work has focused on outlining a direct molecular mechanism involving PBM-generated redox-mediated activation of endogenous latent TGF-β1. Conclusions: Despite its critical roles in these processes, the complexity and cross talk in this potent growth factor signaling network have prevented the development of directed targeted therapeutics. PBM treatments offer a novel therapeutic and discovery tool in this aspect, especially with the growing evidence for its roles in cancer immunotherapy and stem cell biology.

Defocused high-power diode laser accelerates skin repair in a murine model through REDOX state modulation and reepithelization and collagen deposition stimulation

Skin wounds represent a burden in healthcare. Our aim was to investigate for the first time the effects of defocused high-power diode laser (DHPL) on skin healing in an animal experimental model and compare it with gold standard low-level laser therapy. Male Wistar rats were divided into 5 groups: Negative control; Sham; 0.1 W laser (L0.1 W); DHPL Dual 1 W (DHPLD1 W); and DHPL Dual 2 W (DHPLD2 W). Rats were euthanized on days 3, 5, 10, 14 and 21. Clinical, morphological, PicroSirus, oxidative stress (MDA, SOD and GSH) and cytokines (IL-1β, IL-10 and TNF-α) analyses were performed. A faster clinical repair was observed in all laser groups at D10 and D14. DHPLD1 W exhibited lower inflammation and better reepithelization compared to other groups at D10. DHPL protocols modulated oxidative stress by decreasing MDA and increasing SOD and GSH. Collagen maturation was triggered by all protocols tested and L0.1 W modulated cytokines release (IL-1β and TNF-α) at D3. In conclusion, DHPL, especially DHPL1 W protocol, accelerated skin healing by triggering reepithelization and collagen maturation and modulating inflammation and oxidative stress.

Comparative study of an antimicrobial peptide and a neuropeptide conjugated with gold nanorods for the targeted photothermal killing of bacteria

There are certain disadvantages in treating bacterial infections through conventional methods. For this reason, the current study does focus on combating bacterial wound infections by photothermal therapy assisted by gold nanorod-peptide conjugates (GNR-peptide conjugates). Two peptides, the cationic antimicrobial peptide LL-37 and neuropeptide ANGIOPEP-2 both with specificity for targeted bacterial binding, were conjugated with GNR surface through electrostatic interactions. The GNR-peptide conjugates showed good biocompatibility, sufficient stability, enhanced targeting, potential photothermal killing of bacteria, and possible acceleration of wound healing. The photo-biomodulation properties of NIR improved the wound closure rates through enhanced cell migration. The multifunctional LL37-conjugated GNRs significantly enhanced photothermal therapeutic outcomes based on bacterial targeting with promising wound healing properties.

Red-emitting InP quantum dot micro-disk lasers epitaxially grown on (001) silicon

Direct epitaxy of InP quantum dot (QD) lasers on silicon (Si) provides an on-chip red laser source for integrated Si photonics with different applications. Here, we demonstrate the first, to the best of our knowledge, InP QD lasers directly grown on (001) Si. Combining highly emissive InP QDs and a GaAs/Si template with low defect density, continuous-wave (CW) lasing of micro-disk lasers (MDLs) on Si is achieved at room temperature. The lowest threshold of MDLs on Si is ∼500nW, without considering the micro-disk surface absorption efficiency of the pump power. The MDLs grown on the native GaAs substrate with the same growth and fabrication process are compared using statistical data analysis. Similar material characterization results and device performances on these two substrates further confirm the performance of QD lasers on Si. This demonstration paves the way for future realization of integrated photonic circuits with red and near-infrared (NIR) lasers on Si.

The Role of miR-181c in Mechanisms of Diabetes-Impaired Angiogenesis: An Emerging Therapeutic Target for Diabetic Vascular Complications

Diabetes mellitus is estimated to affect up to 700 million people by the year 2045, contributing to an immense health and economic burden. People living with diabetes have a higher risk of developing numerous debilitating vascular complications, leading to an increased need for medical care, a reduced quality of life and increased risk of early death. Current treatments are not satisfactory for many patients who suffer from impaired angiogenesis in response to ischaemia, increasing their risk of ischaemic cardiovascular conditions. These vascular pathologies are characterised by endothelial dysfunction and abnormal angiogenesis, amongst a host of impaired signaling pathways. Therapeutic stimulation of angiogenesis holds promise for the treatment of diabetic vascular complications that stem from impaired ischaemic responses. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis to improve ischaemic complications such as ischaemic heart disease and peripheral artery disease, highlighting the immense unmet need. However, despite significant effort and research, there are no established therapies that directly stimulate angiogenesis in a clinical setting, highlighting the immense unmet need. MicroRNAs (miRNAs) are emerging as powerful targets for multifaceted diseases including diabetes and cardiovascular disease. This review highlights the potential role of microRNAs as therapeutic targets for rescuing diabetes-impaired angiogenesis, with a specific focus on miR-181c, which we have previously identified as an important angiogenic regulator. Here we summarise the pathways currently known to be regulated by miR-181c, which include the classical angiogenesis pathways that are dysregulated in diabetes, mitochondrial function and axonal guidance, and describe how these relate both directly and indirectly to angiogenesis. The pleiotropic actions of miR-181c across multiple key angiogenic signaling pathways and critical cellular processes highlight its therapeutic potential as a novel target for treating diabetic vascular complications.

Photobiomodulation Response From 660 nm is Different and More Durable Than That From 980 nm

BACKGROUND AND OBJECTIVES

Photobiomodulation (PBM) therapy uses light at various wavelengths to stimulate wound healing, grow hair, relieve pain, and more-but there is no consensus about optimal wavelengths or dosimetry. PBM therapy works through putative, wavelength-dependent mechanisms including direct stimulation of mitochondrial respiration, and/or activation of transmembrane signaling channels by changes in water activity. A common wavelength used in the visible red spectrum is ~660 nm, whereas recently ~980 nm is being explored and both have been proposed to work via different mechanisms. We aimed to gain more insight into identifying treatment parameters and the putative mechanisms involved.

STUDY DESIGN/MATERIALS AND METHODS

Fluence-response curves were measured in cultured keratinocytes and fibroblasts exposed to 660 or 980 nm from LED sources. Metabolic activity was assessed using the MTT assay for reductases. ATP production, a major event triggered by PBM therapy, was assessed using a luminescence assay. To measure the role of mitochondria, we used an ELISA to measure COX-1 and SDH-A protein levels. The respective contributions of cytochrome c oxidase and ATP synthase to the PBM effects were gauged using specific inhibitors.

RESULTS

Keratinocytes and fibroblasts responded differently to exposures at 660 nm (red) and 980 nm (NIR). Although 980 nm required much lower fluence for cell stimulation, the resulting increase in ATP levels was short-term, whereas 660 nm stimulation elevated ATP levels for at least 24 hours. COX-1 protein levels were increased following 660 nm treatment but were unaffected by 980 nm. In fibroblasts, SDH-A levels were affected by both wavelengths, whereas in keratinocytes only 660 nm light impacted SDH-A levels. Inhibition of ATP synthase nearly completely abolished the effects of both wavelengths on ATP synthesis. Interestingly, inhibiting cytochrome c oxidase did not prevent the rise in ATP levels in response to PBM treatment.

CONCLUSION

To the best of our knowledge, this is the first demonstration of differing kinetics in response to PBM therapy at red versus NIR wavelength. We also found cell-type-specific differences in PBM therapy response to the two wavelengths studied. These findings confirm that different response pathways are involved after 660 and 980 nm exposures and suggest that 660 nm causes a more durable response. © 2021 Wiley Periodicals LLC.

Photobiomodulation in diabetic wound healing: A review of red and near-infrared wavelength applications

The development of a painless, non-invasive, and faster way to diabetic wound healing is at the forefront of research. The complexity associated with diabetic wounds makes it a cause for concern amongst diabetic patients and the world at large. Irradiation of cells generates a photobiomodulatory response on cells and tissues, directly causing alteration of cellular processes and inducing diabetic wound repair. Photobiomodulation therapy (PBMT) using red and near-infrared (NIR) wavelengths is being considered as a promising technique for speeding up the rate of diabetic wound healing, eradication of pain and reduction of inflammation through the alteration of diverse cellular and molecular processes. This review presents the extent to which the potential of red and NIR wavelengths have been harnessed in PBMT for diabetic wound healing. Important research challenges and gaps are identified and discussed, and future directions mapped out. This review thus provides useful insights and strategies into improvement of PBMT, including its acceptance within the global medical research community.

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.

Beneficial Effects of Near-Infrared Light Photobiomodulation in Linear Morphea: A Case Report

Background: Linear morphea is a variant of scleroderma limited to the skin and underlying tissues secondary to an autoimmune inflammation leading to excess collagen deposition and fibrosis. Apart from topical or oral medications, successful light-based treatments have been reported using phototherapy including Psoralen plus ultraviolet A, photodynamic therapy, carbon dioxide laser, pulsed dye laser, and visible/infrared light. Methods: We report a patient with biopsy-proven infraorbital linear morphea responding to 940 nm near-infrared light photobiomodulation treatments. Results: The patient had excellent cosmesis without textural changes or hypopigmentation despite her darker skin complexion (Fitzpatrick phototype III) after tri-weekly treatments for 8 months. Conclusions: Linear morphea, therefore, may be potentially amenable to home use light-based therapy by using nonthermal nonablative 940 nm photons. To our knowledge, this home-based treatment approach has not been previously reported.

Photobiomodulation therapy inhibits oral submucous fibrosis in mice

Objectives

Oral submucous fibrosis (OSMF) is a chronic inflammatory disease and a potentially malignant oral disorder. However, the best therapeutic treatment for OSMF remains uncertain. Our previous study showed that photobiomodulation (PBM) therapy and forskolin could reduce arecoline‐induced fibrosis reactions via the cAMP pathway. The present study aimed to establish an animal model of areca nut extract (ANE)‐induced OSMF and to evaluate the therapeutic potential of PBM and forskolin for ANE‐induced OSMF.

Subjects and methods

The mice were divided into five groups. The buccal tissues were harvested for histomorphological analysis and immunoblotting.

Results

Our results showed that PBM significantly reduced the development of ANE‐induced OSMF, quantified by changes in submucosal layer thickness and collagen deposition. Additionally, PBM could extensively reduce the protein expression of the fibrotic marker genes alpha‐smooth muscle actin (α‐SMA) and connective tissue growth factor (CTGF) in buccal submucous lesions. However, forskolin treatment significantly decreased the protein expression of fibrotic marker genes but slightly decreased the observed histomorphological changes.

Conclusions

We established an ANE‐induced OSMF mouse model, which also provided a model for the development of a therapeutic treatment for OSMF. The anti‐fibrotic effects of PBM and forskolin may be useful for clinical interventions.

Efficacy and Safety of Pirfenidone in Patients with Second-Degree Burns: A Proof-of-Concept Randomized Controlled Trial

OBJECTIVE

Several studies suggest that pirfenidone may have a potential off-label use for wound healing. However, the effectiveness of this medication in patients with burns remains uncertain. Accordingly, investigators sought to assess wound re-epithelialization in patients with second-degree burns after adding pirfenidone to usual care.

DESIGN AND SETTING

Single-center pilot, proof-of-concept, single-blind randomized controlled trial.

PATIENTS AND INTERVENTION

Eight patients with second-degree burns were treated with occlusive hydrocolloid dressings and were randomly allocated to receive either no additional treatment or pirfenidone.

OUTCOME MEASURES

The primary outcome of the study was to evaluate wound healing between groups based on the thickness of the re-epithelialized epidermis at day 7. Secondary outcomes were to qualitatively assess the development of fibrotic tissue in the dermis, anomalies in the basal membrane, and the development of collagen fibers by histologic analysis. Liver and renal functions were measured daily to assess the overall safety of oral pirfenidone.

MAIN RESULTS

Patients treated with pirfenidone showed a remarkable improvement in wound re-epithelialization at day 7 (148.98 ± 13.64 vs 119.27 ± 15.55 μm; P = .029; 95% confidence interval, 4.14-55.29). Histologic evaluations showed less wound fibrosis in the pirfenidone group.

CONCLUSIONS

A decrease in wound healing time by enhancing wound re-epithelialization was observed with pirfenidone. Larger clinical trials are needed to reach more reliable conclusions.

Low-frequency ultrasound enhances vascular endothelial growth factor expression, thereby promoting the wound healing in diabetic rats

Diabetes is a chronic metabolic disease with a high prevalence worldwide, which typically delays or impairs wound healing, potentially causing death. Low-frequency ultrasound treatment promotes the repair of various injuries and may promote wound healing. The aim of the present study was to determine whether low-frequency ultrasound can accelerate wound healing, as well as investigate its effects on the expression of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1, interleukin (IL)-6 and tumor necrosis factor (TNF)-α in diabetic rats. A total of 45 Wistar rats were intraperitoneally injected with 1% streptozocin following intraperitoneal injection of pentobarbital sodium anesthesia. Subsequently an incision wound was created in the skin of back. The area of the wound was recorded to calculate the rate of wound healing. The expression of VEGF and TGF-β1 was determined via immunohistochemical analysis and their mRNA and protein levels were measured via reverse transcription-quantitative PCR analysis. The results revealed that when compared with the control group, low-frequency ultrasound treatment significantly increased wound healing rate in diabetic rats and markedly increased the mRNA and protein levels of VEGF and TGF-β1. US treatment also reduced the mRNA and protein levels of TNF-α and IL-6. In conclusion, the results of the present study indicated that low-frequency ultrasound promotes the expression of VEGF and TGF-β1, and inhibits the expression of IL-6 and TNF-α, thereby promoting wound healing in diabetic rats.

Fluorescence Imaging of Mitochondrial Redox State to Assess Diabetic Wounds

Background: Diabetes is known to cause delayed wound healing, and chronic non-healing lower extremity ulcers may end with lower limb amputations and mortalities. Given the increasing prevalence of diabetes mellitus worldwide, it is critical to focus on underlying mechanisms of these debilitating wounds to find novel therapeutic strategies and thereby improve patient outcome. Methods: This study aims to design a label-free optical fluorescence imager that captures metabolic indices (NADH and FAD autofluorescence) and monitors the in vivo wound healing progress noninvasively. Furthermore, 3D optical cryo-imaging of the mitochondrial redox state was utilized to assess the volumetric redox state of the wound tissue. Results: The results from our in vivo fluorescence imager and the 3D cryo-imager quantify the differences between the redox state of wounds on diabetic mice in comparison with the control mice. These metabolic changes are associated with mitochondrial dysfunction and higher oxidative stress in diabetic wounds. A significant correlation was observed between the redox state and the area of the wounds. Conclusion: The results suggest that our developed novel optical imaging system can successfully be used as an optical indicator of the complex wound healing process noninvasively.

Photobiomodulation associated to cellular therapy improve wound healing of experimental full thickness burn wounds in rats

Adipose derived stromal vascular fraction (SVF) is a method of cell therapy potentially applicable for treatment of full thickness burns. Here we investigated if the association of photobiomodulation (PBM) with SVF therapy could improve wound healing in experimentally induced full thickness burn wounds in rats compared to the topical agent 2% silver sulfadiazine in a dose-dependent manner. Sixty-six male Wistar rats were divided in 4 groups containing 5 animals each which received the following treatments: 2% sulfadiazine (SD), SVF, SVF plus PBM at 30 mW (SVFL30), and SVF plus PBM at 100 mW (SVFL100). Two donor animals were used for each experimental series with 3, 7 and 30 days. Digital photography, microscopic analysis with Hematoxilin and Eosin (H&E), quantification of collagen type I by picrosirius red staining analysis and wound contraction evaluation were performed in order to quantify the results. At day 3 SVF alone or combined with PBM promoted increased early inflammatory response compared to SD. At day 7 SVFL30 and SVFL100 enhanced inflammatory cells infiltration, angiogenesis and fibroblast content compared to SVF and SD groups. At day 30 collagen concentration and wound contraction were higher in SVFL30 when compared to the other groups. In conclusion PBM promotes a synergistic outcome with SVF therapy with a dose dependent effect potentializing wound healing of experimental full thickness burns in rats through amplification of early inflammatory response, enhanced angiogenesis, fibroblast content, accentuated wound contraction and collagen concentration.

Role of photobiomodulation on the activation of the Smad pathway via TGF-β in wound healing

Wound healing is an essential process in which the separated or destroyed tissue attempts to restore itself into its normal state. In some instances, healing is prolonged and remains stagnant in the inflammatory phase, and is referred to as a chronic wound. At a cellular and molecular level, many factors are required during the process of successful wound healing, such as cytokines, polypeptide growth factors and components of the extracellular matrix (ECM). Transforming growth factor-beta (TGF-β) is considered as one of the essential growth factors in wound healing. Working through the Smad pathway, it is the main inducer of fibroblast differentiation which is essential for wound healing. Photobiomodulation (PBM) shows significant advantages in wound healing, and may stimulate cellular processes and tissue regeneration that results in an increase in growth factors and a decrease in inflammatory cytokines. Moreover, it leads to enhanced cell proliferation, migration, angiogenesis, and increased adenosine triphosphate (ATP) and cytochrome C oxidase (CCO) activity. In this review paper, we discuss the effects of PBM and its role on the activation of the TGF-β/Smad pathway in the process of wound healing.