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

Near-infrared light-triggered silk fibroin hydrogels integrated with polydopamine-modified nanoparticles for enhanced wound healing and infection control

This study presents the development and evaluation of a novel silk fibroin (SF)-based hydrogel composite, SiPDA/Ag-C, enhanced with polydopamine (PDA)-modified silver nanoparticles (Ag@PDA) and PDA-modified curcumin (Cur-PDA), for skin wounds treatment and infection control. Dopamine readily oxidizes and reacts with SF to form hydrogels. By in-situ synthesizing silver nanoparticles (Ag NPs) on the surface of PDA nanospheres, Ag@PDA achieves a dual antibacterial effect. It combines the photothermal antibacterial property of PDA with the ability of Ag NPs to disrupt bacterial membranes and DNA. Coating PDA on the surface of curcumin creates Cur-PDA nanoparticles, which not only enhance curcumin's bioavailability but also integrate curcumin's anti-inflammatory and antioxidant properties with PDA's antioxidant and photothermal antibacterial capabilities. Combining Ag@PDA and Cur-PDA into the SF hydrogel matrix results in the SiPDA/Ag-C hydrogel. The hydrogel leverages the photothermal properties of PDA to achieve non-invasive wound healing under near-infrared (NIR) light irradiation. The SiPDA/Ag-C hydrogel could significantly inhibit the growth of Staphylococcus aureus and Escherichia coli in vitro and in vivo, and promote wound healing by reducing inflammation, enhancing antioxidant capacity, and stimulating tissue regeneration. In vivo study shows that compare with the treatment of SiPDA/Ag-C hydrogel alone, the combined treatment with NIR irradiation could significantly inhibit bacterial growth and improve tissue repair. The hydrogel also exhibited excellent biocompatibility, biodegradability, and minimal cytotoxic effects, making it a promising candidate for advanced wound care and tissue engineering applications.

The Therapeutic and Preventive Effects of Light-Emitting Diode (LED) for Post-Inflammatory Erythema and Hyperpigmentation: A Pilot Study

Background/Purpose Photobiomodulation (PBM) using light-emitting diodes (LEDs) benefits tissue regeneration and wound healing. However, evidence regarding the efficacy of LED for post-inflammatory erythema (PIE) and post-inflammatory hyperpigmentation (PIH) is limited. The aim of this study was to explore the effect of medical LED (830 nm and 590 nm) in the prevention and treatment of PIE and PIH. Methods The in vivo PIE/PIH model was simplified to erythema and pigmentation reaction after acute UVB exposure. 308 nm LED light (225 or 270 mJ/cm2) was induced in vivo in the PIE/PIH model on the thigh of ten healthy subjects. Every subject received therapeutic and preventive irradiation (n = 10 in each group). 830 nm (60 J/cm2) and 590 nm LEDs (20 J/cm2) were irradiated, respectively. For therapeutic irradiation, the PIE/PIH model was induced on D1, and LEDs were irradiated on D0, 1, 3, 6 and 8. For preventive irradiation, LEDs were irradiated on D0, 1, 3, 6, and 8 and the PIE/PIH model was induced on D9. Erythema index (EI), melanin index (MI), transdermal water loss (TEWL), and C-Cube photography were measured during 10-day follow-up visits. Results For therapeutic irradiation, ΔEI and ΔMI in the 830 nm treatment group were significantly lower than in the control group (ΔEI: 9.30 vs. 11.52, p = 0.027; ΔMI: 7.79 vs. 9.25, p = 0.026). No significant difference was found between the 590 nm treatment group and the control group in ΔEI or ∆MI (p > 0.05). For preventive irradiation, ΔEI in the 830 nm prevention group and the 590 nm prevention group were both significantly lower than the control group (830 nm: 9.85 vs. 19.90, p = 0.001; 590 nm: 12.50 vs. 19.90, p = 0.008). No significant difference was found between the two prevention LED groups (p > 0.05). Conclusions Both 830 nm and 590 nm LEDs showed preventive effects for PIE, and 830 nm LEDs could effectively improve PIE and PIH.

Pulsed Red Photobiomodulation Boosts the Inhibition of Oxytocin-Induced Primary Dysmenorrhea in Mice by Suppressing Oxidative Stress and Inflammation

Increasing evidence has underscored the pivotal role of red photobiomodulation (R-PBM) in analgesic and anti-inflammatory processes; nonetheless, research concerning the effects of pulsed wave on primary dysmenorrhea (PD) remains sparse. This study found that pulsed R-PBM significantly diminished pain responses and levels of PGF2α/PGE2, mitigated uterine swelling, augmented antioxidant capacity, and lowered MDA concentrations, which outperformed continuous wave at the same average irradiance. Furthermore, PW treatment substantially reduced ROS levels and enhanced cell viability in PGF2α induced HUSM cells. NOS levels, especially iNOS, were markedly diminished in the uteri of PD mice, accompanied by significant alterations in inflammation-related genes (Jun, Fos, IL1rn, IL17b) and protein levels, along with pronounced downregulation of calcium ion concentrations after pulsed R-PBM intervention. These findings indicated that pulsed R-PBM may mitigate pain by modulating ROS and NO/NOS, mediated oxidative stress and inflammatory responses. Consequently, pulsed R-PBM emerges as a promising therapeutic strategy for PD.

Boosting porphyrin synthesis and ALA-mediated photoinactivation through near-infrared therapy

Photodynamic inactivation (PDI) combines the use of photosensitizers with visible light to produce reactive oxygen species that effectively eliminate pathogens. To investigate the impact of near- infrared therapy (NIRT) on heme biosynthesis and permeability of the pro-photosensitizers 5-aminolevulinic acid (ALA) and Hexyl-ALA (H-ALA) through biofilms, we applied sub-lethal conditions for both NIRT and PDI to maintain intact bacterial viability. During NIRT, the temperature remained below 37°C, permitting rapid heating (ΔT = 11°C) without causing thermal damage. NIRT potentiated the bactericidal effects of ALA-PDI by 3 logs in Staphylococcus aureus RN6390 biofilms and 4 logs in ST5-SCCmecI biofilms. With H-ALA-PDI, reductions of 4 and 6 logs, respectively, were observed. In the case of ALA, this enhancement was partly due to increased porphyrin synthesis, a result not replicated by simple heating. For H-ALA, the enhanced effect of PDI was likely due to biofilm or bacterial membrane destabilization caused by NIRT and H-ALA. Unlike biofilms, applying the same ALA-PDI conditions, the treatment was effective in planktonic S. aureus RN6390 cultures, reducing the bacteria by 3 logs, with no additional benefit from NIRT, suggesting that NIRT primarily aids in penetrating the biofilm matrix rather than the bacterial cells. Confocal fluorescence microscopy confirmed that NIRT-treated biofilms exposed to ALA exhibited higher porphyrin fluorescence than untreated biofilms. These findings support the use of NIRT in enhancing the effectiveness of PDI against bacterial biofilms.

Frailty and comorbidity in older adults with and without diabetes and chronic leg ulcer: A cross-sectional study

This descriptive, cross-sectional study aimed to identify whether having a chronic leg ulcer (CLU), in addition to diabetes, contributed to frailty in individuals ≥65 years old. It also explored the associations between frailty, pre-frailty and other factors. 125 participants aged ≥65 attending outpatient clinics in Ireland were categorised into three groups: (1) diabetes-only and no CLU, (2) CLU-only and no diabetes, and (3) diabetes and CLU. Frailty status was identified using the Groningen Frailty Indicator (GFI) and the Physical Frailty Phenotype (PFP). The mean age was 76.09 ± 7.31. Overall, 90 (72%) had diabetes, and 89 (71.2%) had CLU in the past 6 months. While 124 (99.2%) were frail according to the GFI, 122 (97.6%) were either physically frail (n = 40, 32%) or pre-frail (n = 82, 65.6%) based on the PFP. There was no difference between the three groups regarding general frailty status (p > 0.05). However, being aged ≥75, having CLU and having CLU in addition to diabetes were associated with frailty severity (p < 0.05). Slow gait, inability to go to the toilet and dress/undress independently were the common factors contributing to frailty. Age, comorbidities and CLU were associated with frailty severity. Incorporating multidimensional frailty screening into regular clinic visits for older adults with CLU is recommended.

Red light-emitting diode on skin healing: an in vitro and in vivo experimental study

BACKGROUND

The clinical advantages of light-emitting diode (LED) therapy in skin healing and its underlying mechanism remain subjects of ongoing debate.

OBJECTIVE

This study aims to explore the impact of LED therapy on normal skin keratinocytes (HaCaT) and in the repair of full-thickness dorsal wounds in Wistar rats.

METHODS

HaCaT cell viability (SRB assay) and migration (scratch assay) were assessed under LED therapy, comparing stress conditions (2.5% FBS) with sham irradiation and optimal conditions (10% FBS). In vivo, 50 rats with induced wounds were divided into Sham and LED (daily treatment) groups. Euthanasia occurred at 3, 5, 10, 14, and 21 days for clinical, morphological, oxidative stress (MDA, SOD, and GSH), and cytokine analyses (IL-1β, IL-10, TNF-α).

RESULTS

LED therapy significantly enhanced keratinocytes viability compared to sham irradiation, with minimal impact on cell migration. Clinical benefits were prominent on day 10, influencing inflammation progression and resolution on days 3 and 10. Re-epithelization remained unaffected. Reduced MDA and increased GSH levels were observed throughout, while SOD levels varied temporally. Notably, on day 10, LED significantly decreased IL-1β, IL-10, and TNF-α.

STUDY LIMITATIONS

Although translational, clinical trial confirmation of observed benefits is warranted.

CONCLUSIONS

LED therapy expedites cutaneous healing in the experimental model, primarily modulating inflammation and enhancing antioxidant activity.

NIR Laser Irradiation Promotes Osteogenic Differentiation of PDLSCs Through the Activation of TRPV1 Channels and Subsequent Calcium Signaling

Near-infrared (NIR) irradiation has shown potential to stimulate osteogenic differentiation, but the mechanisms are not fully understood. The study is to investigate the effects of NIR laser irradiation on osteoblastic differentiation. Human periodontal ligament stem cells (hPDLSCs) were cultured in osteogenic medium and exposed to 810 nm NIR laser at 0.5 J/cm2 every 48 h. The transient receptor potential vanilloid (TRPV1) channel inhibitor capsazepine (CPZ) was used to evaluate the role of calcium influx. Osteogenic differentiation was assessed by proliferation (CCK-8), alkaline phosphatase (ALP) activity, mineralization (Alizarin Red), and expression of bone markers by PCR and Western blot over 2 weeks. Intracellular calcium was measured by Fluo-4M dye and flow cytometry. Results showed that NIR irradiation enhanced hPDLSC proliferation, ALP activity, mineralization, and bone marker expression, indicating increased osteogenic differentiation. These effects were inhibited by CPZ. NIR induced a transient rise in intracellular calcium peaking at 3 min, which was blocked by CPZ. In conclusion, this study demonstrates that NIR laser irradiation promotes osteogenic differentiation of PDLSCs through the activation of TRPV1 channels and subsequent calcium signaling. Further research is warranted to optimize the treatment parameters and elucidate the detailed signaling pathways involved, paving the way for the clinical application of NIR therapy in the treatment of bone disorders and periodontal disease.

The combined treatment of gold nanoparticles associated with photobiomodulation accelerate the healing of dermonecrotic lesion

Introduction: The search for fast and efficient treatment for dermonecrotic lesions caused by the venom of the spider from the Loxosceles simillis, is a demand in health. Prednisolone is one of the most used drugs, however it has side effects. In this context, addictionally gold nanoparticles (GNPs) have anti-inflammatory, antioxidant, and antibacterial properties. The use of photobiomodulation has show to be efficient in the process of tissue repair. Therefore, the purpose of this study was to investigate the anti-inflammatory effect of photobiomodulation and GNPs associated or not with a low concentration of prednisolone in animal models of dermonecrotic lesion.Methodology: For this, rabbits with venon-induced dermonecrotic lesion were subjected to topical treatment with prednisolone + laser or GNPs + laser or Pred-GNPs + laser. The area of edema, necrosis and erythema were measured. On the last day of treatment, the animals were euthanized to remove the organs for histopathological and biochemical analysis.Results: All treatments combinations were effective in promoting the reduction of necrotic tissue and erythema.Conclusion: With this results, we suggest that the use of laser and nanoparticles, associated or not with prednisolone, should be considered for the treatment of dermonecrotic injury.

Laser Emission at 675 nm: Molecular Counteraction of the Aging Process

BACKGROUND/OBJECTIVES

Many lasers applied in skin rejuvenation protocols show emissions with wavelengths falling in the red or near-infrared (NIR) bands. To obtain further in vitro data on the potential therapeutic benefits regarding rejuvenation, we employed a 675 nm laser wavelength on cultured human dermal fibroblasts to understand the mechanisms involved in the skin rejuvenation process's signaling pathways by analyzing cytoskeletal proteins, extracellular matrix (ECM) components, and membrane integrins.

METHODS

Normal human dermal fibroblasts (NHDFs) were irradiated with a 675 nm laser 24 h after seeding, and immunofluorescence microscopy and Western blotting were applied.

RESULTS

The results demonstrate that the laser treatment induces significant changes in human dermal fibroblasts, affecting cytoskeleton organization and the production and reorganization of ECM molecules. The cell response to the treatment appears to predominantly involve paxillin-mediated signaling pathways.

CONCLUSIONS

These changes suggest that laser treatment can potentially improve the structure and function of skin tissue, with interesting implications for treating skin aging.

Dual-Responsive Antibacterial Hydrogel Patch for Chronic-Infected Wound Healing

Bacterial infections in chronic wounds, such as bedsores and diabetic ulcers, present significant healthcare challenges. Excessive antibiotic use leads to drug resistance and lacks precision for targeted wound treatment. Our study introduces an innovative solution: a near-infrared (NIR) and pH dual-responsive hydrogel patch incorporating regenerated silk fibroin (RSF) and molybdenum dioxide (MoO2) nanoparticles (NPs), offering enhanced mechanical properties, precise drug release, and superior antibacterial efficacy. The dual-responsive hydrogel patch allows for precise control over antibiotic release triggered by NIR light and pH fluctuations, enabling tailored treatment for infected wounds. First, the pH-responsive characteristic matches the alkaline environment of the infected wound, ensuring on-demand antibiotic release. Second, NIR exposure accelerates antibiotic release, enhancing wound healing and providing additional antibacterial effects. Additionally, the patch further blocks bacterial infection, promotes wound repair, and degrades in sync with the healing process, further bolstering the efficacy against wound infections.

Efficacy and safety of red and infrared light in the adjunctive treatment on diabetic foot ulcers: A systematic review and meta-analysis

BACKGROUND

The use of various adjunctive phototherapies for diabetic foot ulcers (DFUs) makes it difficult to fully understand their roles in current laser-based review studies. Red and infrared light have significant advantages for wound healing. To evaluate the impact of red and infrared light on the healing of DFUs and provide evidence-based recommendations for future clinical adjunctive treatments of DFUs.

METHODS

Multiple databases, including PubMed, EMBASE, Cochrane Library, Web of Science, CINAHL, PEDro, CNKI, CBM, Wanfang, and VIP, were systematically searched for articles published until November 2023. The focus of the search was to identify randomised controlled trials that investigated the effects of red and infrared light on the treatment of DFUs. Data extraction, literature screening, and methodological quality assessment were conducted independently by two researchers. A meta-analysis was performed using RevMan5.4 and STATA16.0 software.

RESULTS

A total of 28 studies, involving 1471 patients, were included. The meta-analysis showed that groups treated with red and infrared light had a significantly higher ulcer healing rate [risk ratio (RR) = 1.93, 95 % confidence interval (CI) (1.63, 2.28), P < 0.00001], shorter ulcer healing time [mean difference (MD) = 18.52, 95 % CI (8.58, 28.47), P < 0.00001], increased peak blood flow velocity in the dorsalis pedis artery [mean difference (MD) = 6.54, 95 % CI (4.01,9.08)], P < 0.00001), and reduced wound pain score [mean difference (MD) = -4.33, 95 % CI (-4.94, -3.71)], P < 0.00001) compared to the control group. However, there was no statistically significant difference in the incidence of adverse events [odds ratio (OR) = 0.32, 95 % CI (0.09, 1.17), P = 0.08] between the two methods.

CONCLUSION

The use of red and infrared light as an adjunctive treatment for DFUs is more beneficial than conventional wound care. However, due to limitations in the quality and sample size of the included studies, further high-quality research is needed to validate these conclusions.

Blue light-driven cell cycle arrest in thyroid cancer via Retinal-OPN3 complex

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy, with a rising incidence. Traditional treatments, such as thyroidectomy and radiotherapy, often lead to significant side effects, including impaired thyroid function. Therefore, there is an urgent need for non-invasive therapeutic approaches. This study aims to explore the potential of photobiomodulation therapy (PBMT), a non-invasive treatment using specific wavelengths of light, in the management of PTC.

METHODS

We investigated the effects of blue light PBMT on PTC cells, focusing on the Retinal-OPSIN 3 (OPN3) complex's role in mediating cellular responses. Blue light exposure was applied to PTC cells, and subsequent changes in cellular proliferation, cell cycle progression, and protein expression were analyzed. Statistical tests, including one-way ANOVA and t-tests, were used to evaluate the significance of the findings.

RESULTS

Blue light exposure led to the dissociation of 11-cis-retinal from OPN3, resulting in the accumulation of all-trans retinal. This accumulation disrupted cellular proliferation pathways and induced G0/G1 cell cycle arrest in PTC cells. The Retinal-OPN3 complex was found to be a key mediator in these processes, demonstrating that thyroid cells can respond to specific light wavelengths and utilize their photoreceptive potential for therapeutic purposes.

CONCLUSIONS

Our findings suggest that PBMT, through the modulation of the Retinal-OPN3 complex, offers a promising non-invasive approach for treating PTC. This study highlights the therapeutic potential of light signal transduction in non-ocular tissues and opens new avenues for non-invasive cancer therapies.

A wearable and stretchable dual-wavelength LED device for home care of chronic infected wounds

Phototherapy can offer a safe and non-invasive solution against infections, while promoting wound healing. Conventional phototherapeutic devices are bulky and limited to hospital use. To overcome these challenges, we developed a wearable, flexible red and blue LED (r&bLED) patch controlled by a mobile-connected system, enabling safe self-application at home. The patch exhibits excellent skin compatibility, flexibility, and comfort, with high safety under system supervision. Additionally, we synthesized a sprayable fibrin gel (F-gel) containing blue light-sensitive thymoquinone and red light-synergistic NADH. Combined with bLED, thymoquinone eradicated microbes and biofilms within minutes, regardless of antibiotic resistance. Furthermore, NADH and rLED synergistically improved macrophage and endothelial cell mitochondrial function, promoting wound healing, reducing inflammation, and enhancing angiogenesis, as validated in infected diabetic wounds in mice and minipigs. This innovative technology holds great promise for revolutionizing at-home phototherapy for chronic infected wounds.

Advancements in employing two-dimensional nanomaterials for enhancing skin wound healing: a review of current practice

The two-dimensional nanomaterials are characterized by their ultra-thin structure, diverse chemical functional groups, and remarkable anisotropic properties. Since its discovery in 2004, graphene has attracted significant scientific interest due to its potential applications in various fields, including electronics, energy systems, and biomedicine. In medicine, graphene is used for designing smart drug delivery systems, especially for antibiotics, and biosensing. Skin trauma is a prevalent dermatological condition that increasingly contributes to morbidities and mortalities, thus representing a significant health burden. During tissue damage, rapid skin repair is crucial to prevent blood loss and infection. Therefore, drugs used for skin trauma must possess antimicrobial and anti-inflammatory properties. Two-dimensional (2D) nanomaterials possess remarkable physical, chemical, optical, and biological characteristics due to their uniform shape, increased surface area, and surface charge. Graphene and its derivatives, transition-metal dichalcogenides (TMDs), black phosphorous (BP), hexagonal boron nitride (h-BN), MXene, and metal-organic frameworks (MOFs) are among the commonly used 2D nanomaterials. Moreover, they exhibit antibacterial and anti-inflammatory properties. This review presents a comprehensive discussion of the clinical approaches employed for wound healing treatment and explores the applications of commonly used 2D nanomaterials to enhance wound healing outcomes.

IL-1β Antagonist Receptor Peptide Associated with Photobiomodulation Accelerates Diabetic Wound Tissue Repair

Chronic hyperglycemia caused by diabetes mellitus (DM) slows down the healing process due to prolonged inflammation which impedes the regeneration progression. Photobiomodulation (PBM) is considered a non-pharmacological intervention and has anti-inflammatory and biostimulatory effects that accelerate the healing process. Currently found IL-1β inhibitors are difficult to implement due to their cytotoxic potential, excessive amounts, and invasive administration, and therefore, the application of this peptide in diabetic wounds represents a promising intervention to help resolve the inflammatory response. This study aimed to investigate the effect of an IL-1β inhibitor molecule associated with PBM irradiation in a model of epithelial injury in diabetic mice. After the induction of the DM model with streptozotocin (STZ), the skin lesion model was implemented through surgical excision. Sixty C57BL/6 mice divided into five experimental groups (n = 12) were used: excisional wound (EW), DM + EW, DM + EW + DAP 1-2 (inhibitor peptide), DM + EW + PBM, and DM + EW + PBM + DAP 1-2. Treatment started 12 h after wound induction and was performed daily for 5 days. Twenty-four hours after the last application, the animals were euthanized and the outer edge of the wound was removed. The results obtained demonstrate that the DM + EW + PBM + DAP 1-2 group caused a reduction in the levels of pro-inflammatory cytokines, an increase in anti-inflammatory cytokines, and an increase in TGF-β and maintenance of the cellular redox state with a consequent reduction in levels of inflammatory infiltrate and concomitant stimulation of type III collagen gene expression, as well as a decrease in the size of the wound in square centimeter 6 days after the injury. Only the combination of therapies was able to favor the process of tissue regeneration due to the development of an approach capable of acting at different stages of the regenerative process, through the mechanisms of action of interventions on the inflammatory process by avoiding its stagnation and stimulating progression of regeneration.

Dose-response and efficacy of 904 nm photobiomodulation on diabetic foot ulcers healing: a randomized controlled trial

PURPOSE

This study aimed to examine the impact of a 904 nm photobiomodulation (PBM) on diabetic ulcers using varying dosages.

METHODS

The study was a randomized, double-blind, placebo-controlled clinical trial that compared treatments using PBM (GaAs 904 nm 30w) with three different energy densities (4 J/cm2; 8 J/cm2; 10 J/cm2) in the healing process of non-infected diabetic foot ulcers. Eighty volunteers (48.75% female; 58.5 ± 11.1 years) were randomized into three intervention groups treated with PBM and one control group (PBM placebo). Volunteers performed up 20 interventions with PBM, either placebo or actual, in conjunction with conventional therapy, which involved dressing the wound with Helianthus annuus vegetable oil. The primary variable was the ulcer size reduction rate.

RESULTS

GaAs 904 nm PBM yielded a clinically and significant ulcer size rate reduction of diabetic foot ulcers, independently of energy density range (p < 0.05). However, 10 J/cm² had 60% of completely healed ulcers and the highest proportion of patients reaching 50% of ulcer reduction rate after 5 weeks of treatment. In addition, only 10 J/cm² showed a significant difference between control group after a 10-week follow-up (p < 0.05).

CONCLUSION

GaAs 904 nm PBM was effective in treating diabetic foot ulcers in this study and a dosage of 10 J/cm², after a 10-week follow-up, proved to be the most effective compared to the other groups.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04246814.

Long-Term Outcome of Photobiomodulation Therapy for Refractory Diabetic Wound After Secretory Carcinoma of the Parotid Gland Surgery: A Case Report

Objective: To evaluate the efficacy and safety of photobiomodulation therapy (PBMT) in the treatment of diabetic patients with refractory wound. Background: Refractory wound is one of the most challenging clinical complications of diabetes mellitus. Studies have shown that PBMT can promote wound healing in many ways. Methods: We reported a 55-year-old male patient with refractory diabetic wound after secretory carcinoma of the parotid gland surgery responding to 810 nm laser. Results: After PBMT, the refractory diabetic wound healed gradually without adverse events. During follow-up 5-years, the healed wound remained stable and showed no signs of recurrence. Conclusions: PBMT can be potentially considered as a therapeutic method in diabetic patients with refractory diabetic wound.

Enhancing Skin Injury Repair: Combined Application of PF-127 Hydrogel and hADSC-Exos Containing miR-148a-3p

The use of exosomes to relieve skin injuries has received considerable attention. The PluronicF-127 hydrogel (PF-127 hydrogel) is a novel biomaterial that can be used to carry biomolecules. This study sought to investigate the impact of exosomes originating from human mesenchymal stem cells (MSCs) developed from adipose tissue (hADSC-Exos) combined with a PF-127 hydrogel on tissue repair and explore the underlying mechanism using in vitro and in vivo experiments. miR-148a-3p is the most expressed microRNA (miRNA) in hADSC-Exos. We found that exosomes combined with the PF-127 hydrogel had a better efficacy than exosomes alone; moreover, miR-148a-3p knockdown lowered its efficacy. In vitro, we observed a significant increase in the tumor-like ability of HUVECs after exosome treatment, which was attenuated after miR-148a-3p knockdown. Furthermore, the effects of miR-148a-3p on hADSC-Exos were achieved through the prevention of PTEN and the triggering of phosphatidylinositol 3-kinase (PI3K)/Akt signaling. In conclusion, our results demonstrated that hADSC-Exos can promote angiogenesis and skin wound healing by delivering miR-148a-3p and have a better effect when combined with the PF-127 hydrogel, which may be an alternative strategy to promote wound healing.

Biphasic photobiomodulation of inflammation in mouse models of common wounds, infected wounds, and diabetic wounds

Bidirectional photobiomodulation (PBM) therapy is an active research area. However, most studies have focused on its dependence on optical parameters rather than on its tissue-dependent effects. We constructed mouse models of wounds in three inflammatory states (normal, low, and high levels of inflammations) to assess the bidirectional regulatory effect of PBM on inflammation. Mice were divided into three groups to prepare common wounds, diabetic wounds, and bacteria-infected wounds. The same PBM protocol was used to regularly irradiate the wounds over a 14 d period. PBM promoted healing of all three kinds of wounds, but the inflammatory manifestations in each were significantly different. In common wounds, PBM slightly increased the aggregation of inflammatory cells and expression of IL-6 but had no effect on the inflammatory score. For wounds in a high level of inflammation caused by infection, PBM significantly increased TNF-α expression in the first 3 d of treatment but quickly eliminated inflammation after the acute phase. For the diabetic wounds in a low level of inflammation, PBM intervention significantly increased inflammation scores and prevented neutrophils from falling below baseline levels at the end of the 14 d observation period. Under fixed optical conditions, PBM has a bidirectional (pro- or anti-inflammatory) effect on inflammation, depending on the immune state of the target organism and the presence of inflammatory stimulants. Our results provide a basis for the formulation of clinical guidelines for PBM application.

Insights into the mechanisms of diabetic wounds: pathophysiology, molecular targets, and treatment strategies through conventional and alternative therapies

Diabetes mellitus is a prevalent cause of mortality worldwide and can lead to several secondary issues, including DWs, which are caused by hyperglycemia, diabetic neuropathy, anemia, and ischemia. Roughly 15% of diabetic patient's experience complications related to DWs, with 25% at risk of lower limb amputations. A conventional management protocol is currently used for treating diabetic foot syndrome, which involves therapy using various substances, such as bFGF, pDGF, VEGF, EGF, IGF-I, TGF-β, skin substitutes, cytokine stimulators, cytokine inhibitors, MMPs inhibitors, gene and stem cell therapies, ECM, and angiogenesis stimulators. The protocol also includes wound cleaning, laser therapy, antibiotics, skin substitutes, HOTC therapy, and removing dead tissue. It has been observed that treatment with numerous plants and their active constituents, including Globularia Arabica, Rhus coriaria L., Neolamarckia cadamba, Olea europaea, Salvia kronenburgii, Moringa oleifera, Syzygium aromaticum, Combretum molle, and Myrtus communis, has been found to promote wound healing, reduce inflammation, stimulate angiogenesis, and cytokines production, increase growth factors production, promote keratinocyte production, and encourage fibroblast proliferation. These therapies may also reduce the need for amputations. However, there is still limited information on how to prevent and manage DWs, and further research is needed to fully understand the role of alternative treatments in managing complications of DWs. The conventional management protocol for treating diabetic foot syndrome can be expensive and may cause adverse side effects. Alternative therapies, such as medicinal plants and green synthesis of nano-formulations, may provide efficient and affordable treatments for DWs.

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.

Acceleration of a delayed healing wound repair model in diabetic rats by additive impacts of photobiomodulation plus conditioned medium of adipose-derived stem cells

Purpose

This study aimed to investigate the effects of photobiomodulation (PBM) and conditioned medium (CM) derived from human adipose-derived stem cells (h-ASCs), both individually and in combination, on the maturation stage of an ischemic infected delayed healing wound model (IIDHWM) in type I diabetic (TIDM) rats.

Methods

The study involved the extraction of h-ASCs from donated fat, assessment of their immunophenotypic markers, cell culture, and extraction and concentration of CM from cultured 1 × 10^6 h-ASCs. TIDM was induced in 24 male adult rats, divided into four groups: control, CM group, PBM group (80 Hz, 0.2 J/cm2, 890 nm), and rats receiving both CM and PBM. Clinical and laboratory evaluations were conducted on days 4, 8, and 16, and euthanasia was performed using CO2 on day 16. Tensiometrical and stereological examinations were carried out using two wound samples from each rat.

Results

Across all evaluated factors, including wound closure ratio, microbiological, tensiometrical, and stereological parameters, similar patterns were observed. The outcomes of CM + PBM, PBM, and CM treatments were significantly superior in all evaluated parameters compared to the control group (p = 0.000 for all). Both PBM and CM + PBM treatments showed better tensiometrical and stereological results than CM alone (almost all, p = 0.000), and CM + PBM outperformed PBM alone in almost all aspects (p = 0.000). Microbiologically, both CM + PBM and PBM exhibited fewer colony-forming units (CFU) than CM alone (both, p = 0.000).

Conclusion

PBM, CM, and CM + PBM interventions substantially enhanced the maturation stage of the wound healing process in IIDHWM of TIDM rats by mitigating the inflammatory response and reducing CFU count. Moreover, these treatments promoted new tissue formation in the wound bed and improved wound strength. Notably, the combined effects of CM + PBM surpassed the individual effects of CM and PBM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01285-3.

Morphological features of the photoplethysmographic signal: a new approach to characterize the microcirculatory response to photobiomodulation

Introduction and Objectives: Advanced analysis of the morphological features of the photoplethysmographic (PPG) waveform may provide greater understanding of mechanisms of action of photobiomodulation (PBM). Photobiomodulation is a non-ionizing, red to near-infrared irradiation shown to induce peripheral vasodilatation, promote wound healing, and reduce pain. Using laser Doppler flowmetry combined with thermal imaging we found previously in a clinical study that PBM stimulates microcirculatory blood flow and that baseline palm skin temperature determines, at least in part, why some individuals respond favorably to PBM while others do not. "Responders" (n = 12) had a skin temperature range of 33°C-37.5°C, while "non-responders" (n = 8) had "cold" or "hot" skin temperature (<33°C or >37.5°C respectively). The continuous PPG signals recorded from the index fingers of both hands in the original clinical study were subjected to advanced post-acquisitional analysis in the current study, aiming to identify morphological features that may improve the accuracy of discrimination between potential responders and non-responders to PBM. Methods: The PPG signals were detrended by subtracting the lower envelope from the raw signal. The Root Mean Square (RMS) and Entropy features were extracted as were two additional morphological features -- Smoothness and number of local extrema per PPG beat (#Extrema). These describe the signal jaggedness and were developed specifically for this study. The Wilcoxon test was used for paired comparisons. Correlations were determined by the Spearman correlation test (rs). Results: The PPG waveforms of responders to PBM had increased amplitude and decreased jaggedness (Baseline vs. 10' post-irradiation: Entropy, 5.0 ± 1.3 vs. 3.9 ± 1.1, p = 0.012; #Extrema, 4.0 ± 1.1 vs. 3.0 ± 1.6, p = 0.009; RMS, 1.6 ± 0.9 vs. 2.3 ± 1.2, p = 0.004; Smoothness, 0.10 ± 0.05 vs. 0.19 ± 0.16, p = 0.016). In addition, unilateral irradiation resulted in a bilateral response, although the response of the contralateral, non-irradiated hand was shorter in duration and lower in magnitude. Although subjects with 'cold,' or 'hot,' baseline skin temperature appeared to have morphologically distinct PPG waveforms, representing vasoconstriction and vasodilatation, these were not affected by PBM irradiation. Conclusion: This pilot study indicates that post-acquisitional analysis of morphological features of the PPG waveform provides new measures for the exploration of microcirculation responsiveness to PBM.

Application of combined photobiomodulation and curcumin-loaded iron oxide nanoparticles considerably enhanced repair in an infected, delayed-repair wound model in diabetic rats compared to either treatment alone

Herein, we attempted to evaluate the therapeutic potential of photobiomodulation (PBM) and curcumin-loaded iron nanoparticles (CUR), alone and in combination, on wound closure rate (WCR), microbial flora by measuring colony-forming units (CFUs), the stereological and biomechanical properties of repairing wounds in the maturation stage of the wound healing course in an ischemic infected delayed healing wound model (IIDHWM) of type I diabetic (TIDM) rats. There were four groups: group 1 was the control, group 2 received CUR, rats in group 3 were exposed to PBM (80 Hz, 890 nm, and 0.2 J/cm2), and rats in group 4 received both PBM and CUR (PBM + CUR). We found CFU was decreased in groups 2, 3, and 4 compared to group 1 (p = 0.000 for all). Groups 2, 3, and 4 showed a considerable escalation in WCR compared to group 1 (p = 0.000 for all). In terms of wound strength parameters, substantial increases in bending stiffness and high-stress load were observed in groups 2, 3, and 4 compared to group 1 (p = 0.000 for all). Stereological examinations revealed decreases in neutrophil and macrophage counts and increases in fibroblast counts in groups 2, 3, and 4compared  to group 1 (p = 0.000 for all). Blood vessel counts were more dominant in the PBM and PBM + CUR groups over group 1 (p = 0.000 for all). CFU and wound strength as well as macrophage, neutrophil, and fibroblast counts were found to be improved in the PBM + CUR and PBM groups compared to the CUR group (ranging from p = 0.000 to p < 0.05). Better results were achieved in the PBM + CUR  treatment  over the PBM therapy. We determined therapy with PBM + CUR, PBM alone, and CUR alone substantially accelerated diabetic wound healing in an IIDHWM of TIDM rats compared to control  group. Concomitantly, the PBM + CUR and PBM groups attained significantly enhanced results for WCR, stereological parameters, and wound strength than the CUR group, with the PBM + CUR results being superior to those of the PBM group.

Mild Photothermal-Stimulation Based on Injectable and Photocurable Hydrogels Orchestrates Immunomodulation and Osteogenesis for High-Performance Bone Regeneration

A photoactivated bone scaffold integrated with minimally invasive implantation and mild thermal-stimulation capability shows great promise in the repair and regeneration of irregularly damaged bone tissues. Developing multifunctional photothermal biomaterials that can simultaneously serve as both controllable thermal stimulators and biodegradable engineering scaffolds for integrated immunomodulation, infection therapy, and impaired bone repair remains an enormous challenge. Herein, an injectable and photocurable hydrogel therapeutic platform (AMAD/MP) based on alginate methacrylate, alginate-graft-dopamine, and polydopamine (PDA)-functionalized Ti3C2 MXene (MXene@PDA) nanosheets is rationally designed for near-infrared (NIR)-mediated bone regeneration synergistic immunomodulation, osteogenesis, and bacterial elimination. The optimized AMAD/MP hydrogel exhibits favorable biocompatibility, osteogenic activity, and immunomodulatory functions in vitro. The proper immune microenvironment provided by AMAD/MP could further modulate the balance of M1/M2 phenotypes of macrophages, thereby suppressing reactive oxygen species-induced inflammatory status. Significantly, this multifunctional hydrogel platform with mild thermal stimulation efficiently attenuates local immune reactions and further promotes new bone formation without the addition of exogenous cells, cytokines, or growth factors. This work highlights the potential application of an advanced multifunctional hydrogel providing photoactivated on-demand thermal cues for bone tissue engineering and regenerative medicine.

Fortifying angiogenic efficacy of conditioned media using phototoxic-free blue light for wound healing

We used a blue organic light-emitting diode (bOLED) to increase the paracrine factors secreted from human adipose-derived stem cells (hADSCs) for producing conditioned medium (CM). Our results showed that while the bOLED irradiation promotes a mild-dose reactive oxygen generation that enhances the angiogenic paracrine secretion of hADSCs, it does not induce phototoxicity. The bOLED enhances paracrine factors via a cell-signaling mechanism involving hypoxia-inducible factor 1 alpha. This study demonstrated that the CM resulting from bOLED treatment shows improved therapeutic effects on mouse wound-healing models. This method contributes to overcoming the barriers to stem-cell therapies, including the toxicity and low yields from other methods such as nanoparticles, synthetic polymers, and even cell-derived vesicles.

Current Therapeutic Modalities for the Management of Chronic Diabetic Wounds of the Foot

Impaired wound healing is common in patients with diabetes mellitus (DM). Different therapeutic modalities including wound debridement and dressing, transcutaneous electrical nerve stimulation (TENS), nanomedicine, shockwave therapy, hyperbaric (HBOT) and topical (TOT) oxygen therapy, and photobiomodulation (PBM) have been used in the management of chronic diabetic foot ulcers (DFUs). The selection of a suitable treatment method for DFUs depends on the hosts' physiological status including the intricacy and wound type. Effective wound care is considered a critical component of chronic diabetic wound management. This review discusses the causes of diabetic wounds and current therapeutic modalities for the management of DFUs, specifically wound debridement and dressing, TENS, nanomedicine, shockwave therapy, HBOT, TOT, and PBM.

Investigating the effects of low intensity visible light on human keratinocytes using a customized LED exposure system

Photobiomodulation (PBM) refers to the use of light to modulate cellular processes, and has demonstrated utility in improving wound healing outcomes, and reducing pain and inflammation. Despite the potential benefits of PBM, the precise molecular mechanisms through which it influences cell behavior are not yet well understood. Inconsistent reporting of key light parameters has created uncertainty around optimal exposure profiles. In addition, very low intensities of light, < 0.1 J/cm², have not been thoroughly examined for their use in PBM. Here, we present a custom-made compact, and modular LED-based exposure system for studying the effects of very low-intensity visible light (cell proliferation, migration, ROS production, and mitochondrial membrane potential) of three different wavelengths in a parallel manner. The device allows for six repeats of three different exposure conditions plus a non-irradiated control on a single 24-well plate. The immortalised human keratinocyte cell line, HaCaT, was selected as a major cellular component of the skin epidermal barrier. Furthermore, an in vitro wound model was developed by allowing the HaCaT to form a confluent monolayer, then scratching the cells with a pipette tip to form a wound. Cells were exposed to yellow (585 nm, 0.09 mW, ~ 3.7 mJ/cm²), orange (610 nm, 0.8 mW, ~ 31 mJ/cm²), and red (660 nm, 0.8 mW, ~ 31 mJ/cm²) light for 10 min. 48 h post-irradiation, immunohistochemistry was performed to evaluate cell viability, proliferation, ROS production, and mitochondrial membrane potential. The results demonstrate increased proliferation and decreased scratch area for all exposure conditions, however only red light increased the mitochondrial activity. Oxidative stress levels did not increase for any of the exposures. The present exposure system provides opportunities to better understand the complex cellular mechanisms driven by the irradiation of skin cells with visible light.

The combined use of photobiomodulation and curcumin-loaded iron oxide nanoparticles significantly improved wound healing in diabetic rats compared to either treatment alone

This experimental study examined the effects of curcumin-loaded iron oxide nanoparticles (CUR), photobiomodulation (PBM), and CUR + PBM treatments on mast cells (MC)s numbers and degranulation, inflammatory cells (macrophages, neutrophils), and wound strength in the last step of the diabetic wound repair process (maturation phase) in a rat model of type one diabetes mellitus (T1DM). T1DM was induced in 24 rats, and 1 month later, an excisional wound was created on each rat's back skin. The rats were then distributed into four groups: (1) untreated diabetic control group (UDCG); (2) rats treated with CUR (CUR); (3) rats exposed to PBM (890 nm, 80 Hz, 0.2 J/cm²) (PBM); (4) rats treated with CUR plus PBM (CUR + PBM). Fifteen days after surgery, skin tissue samples were taken for biomechanical and stereological evaluations. The biomechanical factor of maximum force was observed to be considerably improved in the CUR + PBM (p = 0.000), PBM (p = 0.014), and CUR (p = 0.003) groups compared to the UDCG. CUR + PBM, PBM, and CUR groups had significantly decreased total numbers of MC compared with the UDCG (all, p = 0.001). The results were significantly better in the CUR + PBM (p = 0.000) and PBM (p = 0.003) groups than in the CUR group. Inflammatory cell counts were significantly lower in the CUR + PBM, PBM, and CUR groups than in the UDCG (all, p = 0.0001). In all evaluating methods, the usage of CUR + PBM produced better results than the use of CUR or PBM alone (almost all tests, p = 0.0001). CUR + PBM, PBM, and CUR significantly improved the repair of diabetic skin wounds in type 1 DM rats through significant decreases of MC number, degranulation, and inflammatory cells as well as a noteworthy improvement in wound strength. The impact of CUR + PBM was superior to that of either PBM or CUR alone. It is suggested that CUR + PBM could be used as a MC stabilizer for the effective treatment of some related human diseases.

Impact of photobiomodulation on macrophages and their polarization during diabetic wound healing: a systematic review

This review aims to providing essential information and the current knowledge about the potential role of macrophages, especially their M2 subtypes in different diabetic wounds both in clinical and pre-clinical models under the influence of photobiomodulation (PBM). The long-term goal is to advance the macrophage-based therapies to accelerate healing of diabetic foot ulcers. We reviewed all databases provided by PubMed, Google Scholar, Scopus, Web of Science, and Cochrane precisely from their dates of inception to 25/10/2021. The keywords of Diabetes mellitus diseases, wound healing, macrophage, and photobiomodulation or low-level laser therapy were used in this systematic review.A total of 438 articles were initially identified in pubmed.ncbi.nlm.nih.gov (15 articles), Google scholar (398 articles), Scopus (18 articles), and Web of Science (7 articles). Four hundred sixteen articles that remained after duplicate studies (22 articles) were excluded. After screening abstracts and full texts, 14 articles were included in our analysis. Among them, 4 articles were about the effect of PBM on macrophages in type 2 diabetes and also found 10 articles about the impact of PBM on macrophages in type 1 diabetes. The obtained data from most of the reviewed studies affirmed that the PBM alone or combined with other agents (e.g., stem cells) could moderate the inflammatory response and accelerate the wound healing process in pre-clinical diabetic wound models. However, only very few studies conducted the detailed functions of polarized macrophages and M2 subtypes in wound healing of diabetic models under the influence of PBM. Further pre-clinical and clinical investigations are still needed to investigate the role of M2 macrophages, especially its M2c subtype, in the healing processes of diabetic foot ulcers in clinical and preclinical settings.

Photobiomodulation isolated or associated with adipose-derived stem cells allograft improves inflammatory and oxidative parameters in the delayed-healing wound in streptozotocin-induced diabetic rats

The single and associated impressions of photobiomodulation (PBM) and adipose-derived stem cells (ADS) on stereological parameters (SP), and gene expression (GE) of some antioxidant and oxidative stressors of repairing injured skin at inflammation and proliferation steps (days 4 and 8) of a delayed healing, ischemic, and infected wound model (DHIIWM) were examined in type one diabetic (DM1) rats. DM1 was induced by administration of streptozotocin (40 mg/kg) in 48 rats. The DHIIWM was infected by methicillin-resistant Staphylococcus aureus (MRSA). The study comprised 4 groups (each, n = 6): Group 1 was the control group (CG). Group 2 received allograft human (h) ADSs transplanted into the wound. In group 3, PBM (890 nm, 80 Hz, 0.2 J/cm²) was emitted, and in group 4, a combination of PBM+ADS was used. At both studied time points, PBM+ADS, PBM, and ADS significantly decreased inflammatory cell count (p < 0.05) and increased granulation tissue formation compared to CG (p < 0.05). Similarly, there were lower inflammatory cells, as well as higher granulation tissue in the PBM+ADS compared to those of alone PBM and ADS (all, p < 0.001). At both studied time points, the GE of catalase (CAT) and superoxide dismutase (SOD) was remarkably higher in all treatment groups than in CG (p < 0.05). Concomitantly, the outcomes of the PBM+ADS group were higher than the single effects of PBM and ADS (p < 0.05). On day 8, the GE of NADPH oxidase (NOX) 1 and NOX4 was substantially less in the PBM+ADS than in the other groups (p < 0.05). PBM+ADS, PBM, and ADS treatments significantly accelerated the inflammatory and proliferative stages of wound healing in a DIIWHM with MRSA in DM1 rats by decreasing the inflammatory response, and NOX1 and 4 as well; and also increasing granulation tissue formation and SOD and CAT. The associated treatment of PBM+ADS was more effective than the individual impacts of alone PBM and ADS because of the additive anti-inflammatory and proliferative effects of PBM plus ADS treatments.

Therapeutic Potential of Photobiomodulation for Chronic Kidney Disease

Chronic kidney disease (CKD) is a growing global public health problem. The implementation of evidence-based clinical practices only defers the development of kidney failure. Death, transplantation, or dialysis are the consequences of kidney failure, resulting in a significant burden on the health system. Hence, innovative therapeutic strategies are urgently needed due to the limitations of current interventions. Photobiomodulation (PBM), a form of non-thermal light therapy, effectively mitigates mitochondrial dysfunction, reactive oxidative stress, inflammation, and gut microbiota dysbiosis, all of which are inherent in CKD. Preliminary studies suggest the benefits of PBM in multiple diseases, including CKD. Hence, this review will provide a concise summary of the underlying action mechanisms of PBM and its potential therapeutic effects on CKD. Based on the findings, PBM may represent a novel, non-invasive and non-pharmacological therapy for CKD, although more studies are necessary before PBM can be widely recommended.

Combinatorial wound healing therapy using adhesive nanofibrous membrane equipped with wearable LED patches for photobiomodulation

Wound healing is the dynamic tissue regeneration process replacing devitalized and missing tissue layers. With the development of photomedicine techniques in wound healing, safe and noninvasive photobiomodulation therapy is receiving attention. Effective wound management in photobiomodulation is challenged, however, by limited control of the geometrical mismatches on the injured skin surface. Here, adhesive hyaluronic acid-based gelatin nanofibrous membranes integrated with multiple light-emitting diode (LED) arrays are developed as a skin-attachable patch. The nanofibrous wound dressing is expected to mimic the three-dimensional structure of the extracellular matrix, and its adhesiveness allows tight coupling between the wound sites and the flexible LED patch. Experimental results demonstrate that our medical device accelerates the initial wound healing process by the synergetic effects of the wound dressing and LED irradiation. Our proposed technology promises progress for wound healing management and other biomedical applications.

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.

Stimulatory responses in α- and β-cells by near-infrared (810 nm) photobiomodulation

Significant efforts have been committed to better understand and regulate insulin secretion as it has direct implications on diabetes. The first phase of biphasic insulin secretion in response to glucose lasts about 10 minutes, followed by a more sustained release persisting several hours. Attenuated insulin release in the first phase is typically associated with abnormal β-cells. While near-infrared photobiomodulation (PBM) demonstrates potential for multiple therapeutic applications, photostimulatory effects on α- and β-cells remain to be further elucidated. Herein, we demonstrate that 810 nm PBM exposure at fluence of 9 J/cm² can elevate the intracellular reactive oxygen species within 15 minutes following photostimulation. In addition, calcium spiking showed an approximately 3-fold increase in both ATC1 (α-cells) and BTC6 (β-cells) and correlates with hormone secretion in response to PBM stimulation. Our findings could lay a foundation for the development of non-biologic therapeutics that can augment islet transplantation.

Photobiomodulation at 830 nm Stimulates Migration, Survival and Proliferation of Fibroblast Cells

PURPOSE

Photobiomodulation (PBM) promotes diabetic wound healing by favoring cell survival and proliferation. This study aimed to investigate the potential of PBM in stimulating cellular migration, viability, and proliferation using the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway.

METHODS

The study explored the in vitro effects of near infrared (NIR) light on cell viability (survival) and proliferation as well as the presence of TGF-β1, phosphorylated TGF-β receptor type I (pTGF-βR1) and phosphorylated mothers against decapentaplegic-homolog (Smad)-2/3 (p-Smad2/3) in different fibroblast cell models.

RESULTS

Results show a significant increase in cellular migration in wounded models, and increased viability and proliferation in irradiated cells compared to their respective controls. An increase in the presence of TGF-β1 in the culture media, a reduction in pTGF-βR1 and a slight presence of p-Smad2/3 was observed in the cells.

CONCLUSION

These findings show that PBM at 830 nm using a fluence of 5 J/cm² could induce cell viability, migration and proliferation to favor successful healing of diabetic wounds. This study contributes to the growing body of knowledge on the molecular and cellular effect of PBM and showcases the suitability of PBM at 830 nm in managing diabetic wounds.

Novel therapeutic targets for diabetes-related wounds or ulcers: an update on preclinical and clinical research

INTRODUCTION

Diabetes-related wounds, particularly diabetes-related foot ulcers, are mainly caused by lack of foot sensation and high plantar tissue stress secondary to peripheral neuropathy, ischemia secondary to peripheral artery disease, and dysfunctional wound healing. Current management of diabetes-related wounds involves the offloading of high foot pressures and the treatment of ischemia through revascularization. Despite these treatments, the global burden of diabetes-related wounds is growing, and thus, novel therapies are needed. The normal wound healing process is a coordinated remodeling process orchestrated by fibroblasts, endothelial cells, phagocytes, and platelets, controlled by an array of growth factors. In diabetes-related wounds, these coordinated processes are dysfunctional. The past animal model and human research suggest that prolonged wound inflammation, failure to adequately correct ischemia, and impaired wound maturation are key therapeutic targets to improve diabetes-related wound healing.

AREAS COVERED

This review summarizes recent preclinical and clinical research on novel diabetes-related wound treatments. Animal models of diabetes-related wounds and recent studies testing novel therapeutic agents in these models are described. Findings from clinical trials are also discussed. Finally, challenges to identifying and implementing novel therapies are described.

EXPERT OPINION

Given the growing volume of promising drug therapies currently under investigation, it is expected within the next decade, that diabetes-related wound treatment will be transformed.

Wound Healing Activities and Potential of Selected African Medicinal Plants and Their Synthesized Biogenic Nanoparticles

In Africa, medicinal plants have been traditionally used as a source of medicine for centuries. To date, African medicinal plants continue to play a significant role in the treatment of wounds. Chronic wounds are associated with severe healthcare and socio-economic burdens despite the use of conventional therapies. Emergence of novel wound healing strategies using medicinal plants in conjunction with nanotechnology has the potential to develop efficacious wound healing therapeutics with enhanced wound repair mechanisms. This review identified African medicinal plants and biogenic nanoparticles used to promote wound healing through various mechanisms including improved wound contraction and epithelialization as well as antibacterial, antioxidant and anti-inflammatory activities. To achieve this, electronic databases such as PubMed, Scifinder^® and Google Scholar were used to search for medicinal plants used by the African populace that were scientifically evaluated for their wound healing activities in both in vitro and in vivo models from 2004 to 2021. Additionally, data on the wound healing mechanisms of biogenic nanoparticles synthesized using African medicinal plants is included herein. The continued scientific evaluation of wound healing African medicinal plants and the development of novel nanomaterials using these plants is imperative in a bid to alleviate the detrimental effects of chronic wounds.

Photobiomodulation therapy for the prevention of acute radiation dermatitis in breast cancer patients undergoing hypofractioned whole-breast irradiation (LABRA trial)

OBJECTIVES

To evaluate the efficacy of photobiomodulation therapy in breast cancer patients post-lumpectomy undergoing hypofractionated whole-breast irradiation (HF-WBI) for the prevention and management of acute radiodermatitis (ARD).

MATERIALS AND METHODS

A randomized, multicentric clinical trial (LABRA trial, NCT03924011) was set up at the Limburg Oncology Center, including the Jessa Hospital (Hasselt, BE) and Ziekenhuis Oost-Limburg (Genk, BE). A total of 71 breast cancer patients planned to undergo HF-WBI were randomized to one of the two study arms: the control group (n = 32) or the PBM group (n = 39). The PBM group received the standard institutional skincare combined with PBM (2×/week) during the complete radiotherapy (RT) course. Patients in the control group received the standard skincare combined with placebo treatment (2x/week). Patients' skin reactions were evaluated weekly during the RT treatment by using the modified version of the Radiation Therapy Oncology Group (RTOG) criteria.

RESULTS

At week 3 of RT, one patient presented a grade 2 and one patient a grade 3 skin reaction in the control group, while in the PBM group, all patients still presented grade 1 ARD. At the final RT session 28% of the patients presenting grade 2-3 ARD, while in the PBM group 10% presented grade 2 and no grade 3 ARD. PBM reduced the incidence of severe ARD by 18%. However, the difference was not significant (p = 0.053).

CONCLUSION

Based on the LABRA trial results, PBM seems not able to reduce the incidence of severe ARD in breast cancer patients undergoing HF-WBI. Research in a larger patient population is recommended.