Topical antimicrobial photodynamic therapy improves angiogenesis in wounds of diabetic mice

Multifunctional Nanosystem for Dual Anti-Inflammatory and Antibacterial Photodynamic Therapy in Infectious Diabetic Wounds

Infectious diabetic wounds present a substantial challenge, characterized by inflammation, infection, and delayed wound healing, leading to elevated morbidity and mortality rates. In this work, we developed a multifunctional lipid nanoemulsion containing quercetin, chlorine e6, and rosemary oil (QCRLNEs) for dual anti-inflammatory and antibacterial photodynamic therapy (APDT) for treating infectious diabetic wounds. The QCRLNEs exhibited spherical morphology with a size of 51 nm with enhanced encapsulation efficiency, skin permeation, and localized delivery at the infected wound site. QCRLNEs with NIR irradiation have shown excellent wound closure and antimicrobial properties in vitro, mitigating the nonselective cytotoxic behavior of PDT. Also, excellent biocompatibility and anti-inflammatory and wound healing responses were observed in zebrafish models. The infected wound healing properties in S. aureus-infected diabetic rat models indicated re-epithelization and collagen deposition with no signs of inflammation. This multifaceted approach using QCRLNEs with NIR irradiation holds great promise for effectively combating oxidative stress and bacterial infections commonly associated with infected diabetic wounds, facilitating enhanced wound healing and improved clinical outcomes.

Role of Photodynamic Therapy in Osteonecrosis and Osteoradionecrosis of the Jaws: A Systematic Review

Aim

Photodynamic therapy (PDT) is a minimally invasive treatment modality that has been used clinically for early stage and inoperable cancers. Successful use of this atraumatic therapy in osteoradionecrosis (ORN) and osteonecrosis of the jaws (ONJ) has been documented in the literature. The aim of this review was to systematically evaluate the role of photodynamic therapy in ORN and ONJ.

Methods

Two independent reviewers conducted an elaborate search in PubMed, Google Scholar and Cochrane's CENTRAL database for studies published on PDT as stand-alone or adjuvant therapy in ORN/ONJ until June 2022. The present study was based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Demographic data, type and stage of necrosis of the jaws, site, PDT protocol, time to heal and follow-up were evaluated. Eighteen articles were included totally based on the inclusion and exclusion criteria for final analysis.

Results

A total of 94 patients were included in the present review out of which 36 were males and 58 were females. Five studies reported the use of PDT as an adjuvant therapy in ORN. Thirteen studies reported successful outcomes with PDT in ONJ. Complete epithelialization was achieved with PDT ± other adjuvants in 86/94 (91.48%) patients. The time taken for regression of the lesion ranged between 4 days and 12 months with PDT in the present study.

Conclusion

The reviewed studies demonstrate the effectiveness of PDT, as an adjuvant therapy, in managing various stages of ORN and ONJ.

Expected role of photodynamic therapy to relieve skin damage in nuclear or radiological emergency: Review

Nuclear and radiological accidents can occur due to poor management, in transportation, radiation therapy and nuclear wards in hospitals, leading to extreme radiation exposure and serious consequences for human health. Additionally, in many of previous radiological accidents, skin damage was observed in patients and survivors due to the high radiation exposure. However, as part of a medical countermeasures in a nuclear/radiological emergency, it is critical to plan for the treatment of radiation-induced skin damage. Hence, the new, non-invasive technology of photodynamic therapy (PDT) is projected to be more effectively used for treating skin damage caused by high-dose radiation. PDT plays an important role in treating, repairing skin damage and promoting wound healing as evidenced by research. This review, highlighted and recommended potential impacts of PDT to repair and decrease radiation-induced skin tissue damage. Moreover, we have suggested some photosensitizer (PS) agent as radio-mitigator drugs to decrease radiobiological effects.

Photodynamic therapy mediated by methylene blue-loaded PEG accelerates skin mouse wound healing: an immune response

PURPOSE

Conventional approaches for enhancing wound healing may not always yield satisfactory results. Instead, we test the effectiveness of a newly developed photodynamic therapy (PDT) that uses methylene blue (MB) loaded with polyethylene glycol (PEG) (MB-PEG) hydrogel to accelerate wound healing process in mice.

METHODS

A dorsal skin incision with 6 mm punch which topically subjected to MB-PEG hydrogel and a low-level laser light of red light to assess the regeneration process of wounded skin. A total of 63 adult male CD1 mice divided into normal group (no treatment) and other wound groups received different treatments of laser (650 ± 5 nm and power intensity of 180 mW/cm2), MB-PEG, or PDT (MB-PEG followed by laser). The wound healing parameters were investigated by histological examination of the skin and measuring of proinflammatory cytokines at the early stage (48 h) and a late one on day 21.

RESULTS

at 48 h, the score of tissue granulation, inflammation, and angiogenesis process were markedly improved in wounded groups that received MB + PEG combined with laser compared to the group treated with laser alone. On day 21, a significant improvement of the inflammation was detected in the group treated with MB + PEG plus laser compared to the other groups. At 48 h, the upregulated serum levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the wound group were significantly (P < 0.001) reduced in the group treated with MB + PEG combined with laser.

CONCLUSION

MB-PEG based hydrogel improves and accelerates wound closure in the context of laser compared to either single treatment.

Evaluation of the potential of Delta-aminolevulinic acid for simultaneous detection of bioburden and anti-microbial photodynamic therapy of MRSA infected wounds in Swiss albino mice

BACKGROUND

The dramatic increase of drug-resistant bacteria necessitates urgent development of platforms to simultaneously detect and inactivate bacteria causing wound infections, but are confronted with various challenges. Delta amino levulinic acid (ALA) induced protoporphyrin IX (PpIX) can be a promising modality for simultaneous bioburden diagnostics and therapeutics. Herein, we report utility of ALA induced protoporphyrin (PpIX) based simultaneous bioburden detection, photoinactivation and therapeutic outcome assessment in methicillin resistant Staphylococcus aureus (MRSA) infected wounds of mice.

METHODS

MRSA infected wounds treated with 10% ALA were imaged with help of a blue LED (∼405 nm) based, USB powered, hand held device integrated with a modular graphic user interface (GUI). Effect of ALA application time, bacteria load, post bacteria application time points on wound fluorescence studied. PpIX fluorescence observed after excitation with blue LEDs was used to detect bioburden, start red light mediated antimicrobial photodynamic therapy (aPDT), determine aPDT effectiveness and assess selectivity of the approach.

RESULTS

ALA-PpIX fluorescence of wound bed discriminates infected from uninfected wounds and detects clinically relevant load. While wound fluorescence pattern changes as a function of ALA incubation and post infection time, intra-wound inhomogeneity in fluorescence correlates with the Gram staining data on presence of biofilms foci. Lack of red fluorescence from wound granulation tissue treated with ALA suggests selectivity of the approach. Further, significant reduction (∼50%) in red fluorescence, quantified using the GUI, relates well with bacteria load reduction observed post topical aPDT.

CONCLUSION

The potential of ALA induced PpIX for simultaneous detection of bioburden, photodynamic inactivation and "florescence-guided aPDT assessment" is demonstrated in MRSA infected wounds of mice.

Evaluation of antimicrobial photodynamic action of a pluronic and pectin based film loaded with methylene blue against methicillin resistantStaphylococcus aureus

Antimicrobial wound dressings play a crucial role in treatment of wound infections. However, existing commercial options fall short due to antibiotic resistance and the limited spectrum of activity of newly emerging antimicrobials against bacteria that are frequently encountered in wound infections. Antimicrobial photodynamic therapy (aPDT) is very promising alternative therapeutic approach against antibiotic resistant microbes such as methicillin resistantStaphylococcus aureus (MRSA). However, delivery of the photosensitizer (PS) homogeneously to the wound site is a challenge. Though polymeric wound dressings based on synthetic and biopolymers are being explored for aPDT, there is paucity of data regarding theirin vivoefficacy. Moreover, there are no studies on use of PS loaded, pluoronic (PL) and pectin (PC) based films for aPDT. We report development of a polymeric film for potential use in aPDT. The film was prepared using PL and PC via solvent casting approach and impregnated with methylene blue (MB) for photodynamic inactivation of MRSAin vitroandin vivo. Atomic force microscopic imaging of the films yielded vivid pictures of surface topography, with rough surfaces, pores, and furrows. The PL:PC ratio (2:3) was optimized that would result in an intact film but exhibit rapid release of MB in time scale suitable for aPDT. The film showed good antibacterial activity against planktonic suspension, biofilm of MRSA upon exposure to red light. Investigations on MRSA infected excisional wounds of mice reveal that topical application of MB loaded film for 30 min followed by red light exposure for 5 min (fluence; ∼30 J cm-2) or 10 min (fluence; ∼60 J cm-2) reduces ∼80% or ∼92% of bioburden, respectively. Importantly, the film elicits no significant cytotoxicity against keratinocytes and human adipose derived mesenchymal stem cells. Taken together, our data demonstrate that PS-loaded PL-PC based films are a promising new tool for treatment of MRSA infected wounds.

Laser Devices and Autologous Platelet Concentrates in Prevention and Treatment of Medication-Related Osteonecrosis of the Jaws: A Systematic Review

Background and Objectives: Medication-related osteonecrosis of the jaws (MRONJ) is a disease that affects many patients taking anti-angiogenic and antiresorptive medicines. Since the pathogenetic mechanism is still partially unknown, preventive strategies, as well as treatment alternatives, are needed. Therefore, the aim of this research is to describe the main evidence from the last 10 years of clinical trials regarding the use of auxiliary devices such as autologous platelet concentrates (APCs) and laser, other than their effects against MRONJ disease onset or therapy. Advantages in the healing process and recurrence rates were also analyzed. Materials and Methods: A systematic search of the electronic databases of PubMed and Scopus was carried out. Data from the studies were analyzed, and the risk of bias was evaluated. Results: Nineteen studies between interventional studies, observational studies, and cohort studies have been considered in this review. Conclusions: Based on the studies included, the literature analysis shows that APCs could be a beneficial alternative in preventing and treating MRONJ. Laser technology, as a surgical tool or used on the antimicrobial photodynamic or photobiomodulation side, has been becoming increasingly popular in the last few years. The latest proposal concerning the combination of both auxiliary tools suggests interesting effects, but more studies should be conducted to evaluate eventual relapses and long-term consequences.

The photosensitizer-based therapies enhance the repairing of skin wounds

Wound repair remains a clinical challenge and bacterial infection is a common complication that may significantly delay healing. Therefore, proper and effective wound management is essential. The photosensitizer-based therapies mainly stimulate the photosensitizer to generate reactive oxygen species through appropriate excitation source irradiation, thereby killing pathogenic microorganisms. Moreover, they initiate local immune responses by inducing the recruitment of immune cells as well as the production of proinflammatory cytokines. In addition, these therapies can stimulate the proliferation, migration and differentiation of skin resident cells, and improve the deposition of extracellular matrix; subsequently, they promote the re-epithelialization, angiogenesis, and tissue remodeling. Studies in multiple animal models and human skin wounds have proved that the superior sterilization property and biological effects of photosensitizer-based therapies during different stages of wound repair. In this review, we summarize the recent advances in photosensitizer-based therapies for enhancing tissue regeneration, and suggest more effective therapeutics for patients with skin wounds.

Photobiomodulation and photodynamic therapy applied after electrocauterization for skin healing optimization in rats

Photobiomodulation-PBM and Photodynamic Therapy-PDT have been used to induce healing. However, the effects of these therapies on skin-lesions induced by electrocautery are unknown, aiming at more favorable clinical and esthetic results. Electrocauterization was done in 78-female Wistar-rats using a system that includes an electrocautery and red-LED. The groups were: No injury, Injury, Injury + ALA (topical 5-aminolevulinic acid application), Injury + LED and Injury + ALA + LED (topical ALA application followed by photoactivation with LED). After 2nd, 7th and 14th days post-injury, immuno-histomorphometric analyses (inflammatory infiltrate, blood vessels, fibroblasts, eschar/epidermal thickness, IL-10 and VEGF) and biochemical assays of MPO (neutrophil), NAG (macrophage), nitrite, DCF (H₂ O₂ ), carbonyl (membrane's damage), sulfhydryl (membrane's integrity), SOD, GSH, hydroxyproline and re-epithelialization area were performed. The Injury + LED and Injury + ALA + LED groups controlled inflammation and oxidative stress, favoring angiogenesis, fibroblasts proliferation and collagen formation. Therefore, the PBM or PDT was effective in tissue formation with thinner eschar and epidermis, resulting in less scarring after electrocauterization.

Natural Photosensitizers in Antimicrobial Photodynamic Therapy

Health problems and reduced treatment effectiveness due to antimicrobial resistance have become important global problems and are important factors that negatively affect life expectancy. Antimicrobial photodynamic therapy (APDT) is constantly evolving and can minimize this antimicrobial resistance problem. Reactive oxygen species produced when nontoxic photosensitizers are exposed to light are the main functional components of APDT responsible for microbial destruction; therefore, APDT has a broad spectrum of target pathogens, such as bacteria, fungi, and viruses. Various photosensitizers, including natural extracts, compounds, and their synthetic derivatives, are being investigated. The main limitations, such as weak antimicrobial activity against Gram-negative bacteria, solubility, specificity, and cost, encourage the exploration of new photosensitizer candidates. Many additional methods, such as cell surface engineering, cotreatment with membrane-damaging agents, nanotechnology, computational simulation, and sonodynamic therapy, are also being investigated to develop novel APDT methods with improved properties. In this review, we summarize APDT research, focusing on natural photosensitizers used in in vitro and in vivo experimental models. In addition, we describe the limitations observed for natural photosensitizers and the methods developed to counter those limitations with emerging technologies.

Photodynamic Therapy Delays Cutaneous Wound Healing in Mice

BACKGROUND

Cutaneous wound healing is a complex, dynamic physiological process. Traditional methods of promoting wound healing are not always effective. Consequently, alternative modalities, such as photodynamic therapy (PDT), are needed. We examined the effectiveness and underlying mechanisms of PDT in a murine model of acute wound healing.

METHODS

Two excisional wounds were produced, one on each side of the midline, in C57bL/6J mice. Methyl 5-aminolevulinate hydrochloride (MAL) was applied to the right-side wound. After 1 to 3 hours of incubation, the wound was irradiated with red light. The left-side wound was not treated with MAL or red light. On Day 14, the wounds were excised and subjected to histological and immunohistochemical analysis.

RESULTS

During the first week, no difference was seen between the two sides. However, at week 2, PDT-treated wounds exhibited delayed re-epithelialization. On Day 14, hematoxylin and eosin (HE) staining showed a continuous epithelial lining in untreated wounds. In contrast, PDT-treated wounds partially lacked epithelium in the wound bed. Masson's Trichrome (MTC) staining showed a thicker dermis and more collagen fibers and inflammatory cells in PDT-treated wounds than in untreated wounds. Immunohistochemical analyses showed significantly fewer CD31⁺ blood vessels and greater collagen III density in PDT-treated wounds than in untreated wounds. However, treated and untreated wounds did not differ in collagen I density.

CONCLUSIONS

PDT delayed acute wound healing in a murine model of secondary intention wound healing.

Antimicrobial photodynamic and photobiomodulation adjuvant therapies for prevention and treatment of medication-related osteonecrosis of the jaws: Case series and long-term follow-up

BACKGROUND

Medication-Related Osteonecrosis of the Jaws (MRONJ) incidence are increasing among elderly. Treatment can be challenging. Prevent or treatment protocols that control evolution of the lesion are warranted.

OBJECTIVE

To observe long-term outcomes of two protocols based on photonics [antimicrobial photodynamic therapy (aPDT) and photobiomodulation (PBM)] for prevention and treatment of MRONJ lesions.

METHODS

In a prospective study, patients who needed oral surgery and had been exposed to antiresorptive drugs were long-term followed-up. For MRONJ prevention, immediately after tooth extraction aPDT was applied. For aPDT a 0.01 % methylene blue solution was applied inside socket for 5 min followed by irradiation with a diode laser [660 nm, 0.028cm², 0.1 W, 3.57 W/cm², 90 s and 9 J per point, 321 J/cm², at least at in 3 points (laser probe was placed at central, and two equidistant points) and total energy of 27J]. Irradiation was repeated weekly until total tissue repair. MRONJ treatment included preoperative aPDT sessions until signs and symptoms of infection had reduced. Then, after necrotic bone removal, aPDT was applied inside surgical wounds and re-applied weekly until healing. Antibiotics were administered pre or postoperatively for no longer than 7 days. PBM therapy was applied with 808 nm diode laser, 0.028cm², 0.1 W, 3.57 W/cm², 30 s, 107 J/cm², 3 J and total energy of 12 J until evidence of remission.

RESULTS

Eighteen patients underwent preventive protocol, and none presented signs of MRONJ after a follow-up of at least 6 months. Seventeen patients presented with MRONJ underwent aPDT protocol and sixteen of them showed total regression of lesions.

PRACTICAL IMPLICATIONS

aPDT and PBM therapy protocols appear to be effective as adjuvant approach not only for preventing MRONJ development due to tooth extraction but for treating MRONJ lesions at early stages with no adverse effects.

Antimicrobial photodynamic therapy in skin wound healing: A systematic review of animal studies

Bacterial infection is a common wound complication that can significantly delay healing. Classical local therapies for infected wounds are expensive and are frequently ineffective. One alternative therapy is photodynamic therapy (PDT). We conducted a systematic review to clarify whether PDT is useful for bacteria-infected wounds in animal models. PubMed and Medline were searched for articles on PDT in infected skin wounds in animals. The language was limited to English. Nineteen articles met the inclusion criteria. The overall study methodological quality was moderate, with a low-moderate risk of bias. The animal models were mice and rats. The wounds were excisional, burn, and abrasion wounds. Wound size ranged from 6 mm in diameter to 1.5 × 1.5 cm² . Most studies inoculated the wounds with Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus. Eleven and 17 studies showed that the PDT of infected wounds significantly decreased wound size and bacterial counts, respectively. Six, four, and two studies examined the effect of PDT on infected wound-cytokine levels, wound-healing time, and body weight, respectively. Most indicated that PDT had beneficial effects on these variables. PDT accelerated bacteria-infected wound healing in animals by promoting wound closure and killing bacteria.

Antimicrobial photodynamic therapy improves the alveolar repair process and prevents the occurrence of osteonecrosis of the jaws after tooth extraction in senile rats treated with zoledronate

This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) in the alveolar repair of rats with major risk factors for bisphosphonate-related osteonecrosis of the jaws (BRONJ). Senile rats received 0.45 ml of vehicle (VEH and VEH/aPDT) or 0.45 ml of zoledronate (ZOL and ZOL/aPDT) every three days for seven weeks. After three weeks of treatment, the first lower left molar was extracted. VEH/aPDT and ZOL/aPDT were submitted to aPDT on the extraction site at 0, 2 and 4 days postoperatively. Euthanasia was performed 28 days postoperatively and the extraction site was evaluated by clinical, histological, histometric, histochemical and immunohistochemical analysis. ZOL showed tissue repair impairment; lower percentage of newly formed bone tissue (NFBT); higher percentage of non-vital bone tissue (NVBT); fewer mature collagen fibers and increased immunolabeling for tumor necrosis factor (TNFα), interleukin (IL)-1β and IL-6. ZOL/aPDT showed clinical and histological characteristics of the extraction site, percentage of NFBT and percentage of mature collagen fiber similar to VEH. Percentage of NVBT and immunolabeling for inflammatory cytokines in ZOL/aPDT was lower than in ZOL. Immunolabeling for tartarato-resistant acid phosphatase (TRAP) was lower in ZOL and ZOL/aPDT. aPDT in the dental extraction site improves tissue repair process and prevents the occurrence of BRONJ-like lesions after tooth extraction.

Synergistic in vitro effects of indocyanine green and ethylenediamine tetraacetate-mediated antimicrobial photodynamic therapy combined with antibiotics for resistant bacterial biofilms in diabetic foot infection

BACKGROUND

Antibiotic resistance has emerged as one of the most important determinants in diabetic foot infections outcomes. Antimicrobial Photodynamic therapy(A-PDT) or Photodynamic antimicrobial chemotherapy (PACT) has been proposed as an alternative approach for inactivating bacteria, especially resistant bacterial biofilms. This research investigated the synergistic effects of PACT mediated by the photosensitizer indocyanine green (ICG) and ethylenediamine tetraacetate (EDTA) combined with antibiotics against common pathogens of diabetic foot ulcer infection, including Staphylococcus aureus and Pseudomonas aeruginosa, in vitro.

METHODS

Planktonic bacteria and biofilms of S. aureus and P. aeruginosa were incubated with ICG and EDTA, and then exposed to laser treatment. Quantitative viable counting estimates the phototoxic effects on S. aureus and P. aeruginosa. The susceptibility of methicillin-resistant S. aureus (MRSA) and multidrug-resistant P. aeruginosa (MRPA) to PACT treatment was detected by disk diffusion and micro-broth dilution methods. Confocal microscopy was used to detect the morphology of biofilms treated with PACT and antibiotics. The resazurin assay was used to quantify the metabolic activity of bacteria in biofilms.

RESULTS

PACT mediated by ICG and EDTA led to a more pronounced antibacterial effect in S. aureus and P. aeruginosa compared with ICG alone-mediated PACT. P. aeruginosa was more sensitive to ICG and EDTA-mediated PACT than S. aureus. After PACT treatment, the susceptibility of MRSA and MRPA to antibiotics increased. Furthermore, PACT combined with antibiotic treatment significantly contributed to killing bacteria in the biofilm and disrupting biofilm structure.

CONCLUSIONS

ICG and EDTA-mediated PACT combined with antibiotics synergistically enhanced the effects of sterilization and biofilm destruction.

Co-Administered Polymeric Nano-Antidotes for Improved Photo-Triggered Response in Glioblastoma

Polymer-based nanoparticles (NPs) are useful vehicles in treating glioblastoma because of their favorable characteristics such as small size and ability to cross the blood–brain barrier, as well as reduced immunogenicity and side effects. The use of a photosensitizer drug such as Verteporfin (BPD), in combination with a pan-vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI), Cediranib (CED), encapsulated in NPs will provide the medical field with new research on the possible ways to treat glioblastoma. Concomitant administration of BPD and CED NPs have the potential to induce dual photocytotoxic and cytostatic effects in U87 MG cells by (1) remotely triggering BPD through photodynamic therapy by irradiating laser at 690 nm and subsequent production of reactive oxygen species and (2) inhibiting cell proliferation by VEGFR interference and growth factor signaling mechanisms which may allow for longer progression free survival in patients and fewer systemic side effects. The specific aims of this research were to synthesize, characterize and assess cell viability and drug interactions for polyethylene-glycolated (PEGylated) polymeric based CED and BPD NPs which were less than 100 nm in size for enhanced permeation and retention effects. Synergistic effects were found using the co-administered therapies compared to the individual drugs. The major goal of this research was to investigate a new combination of photodynamic-chemotherapy drugs in nano-formulation for increased efficacy in glioblastoma treatment at reduced concentrations of therapeutics for enhanced drug delivery in vitro.

Wound healing activity of curcumin conjugated to hyaluronic acid: in vitro and in vivo evaluation

Curcumin is a promising wound healing agent but its clinical application is limited due to hydrophobicity and lack of stability. In this article, we report the results of a study on wound healing efficacy of curcumin conjugated to hyaluronic acid (HA) which is a natural polysaccharide known to influence the healing process. Studies on proliferation, antioxidant activity and scratch wound healing carried out in human keratinocyte cells revealed that HA-conjugated curcumin treatment enhanced cell proliferation, decreased oxidative damage induced by H₂O₂ and also improved migration of cells in scratch wounds as compared to treatment with native curcumin. HA conjugated curcumin exhibited bactericidal activity in dark and phototoxicity when irradiated with blue light against antibiotic resistant bacteria. Furthermore, wound healing efficacy studied in diabetic mice demonstrated that topical application of the conjugate on wounds led to better healing as compared to treatment with HA-free curcumin and HA alone. These results suggest that HA conjugation is a promising formulation of curcumin for enhancing its healing efficacy.

pH influences the biocompatibility of methylene blue solutions

OBJECTIVE

The aim of this study was to investigate the biocompatibility of methylene blue at different pH levels through the method of implantation in subcutaneous tissue.

MATERIALS AND METHODS

Eighty-four sterilized polyethylene tubes were allocated in the subcutaneous tissue of 28 rats, each one receiving four tubes, set into four groups: group tube (G-T)-empty tube, fibrin group (G-F)-tube filled with fibrin sponge, group methylene blue pH 7 (G-MB/pH 7)-tube filled with fibrin sponge soaked by methylene blue (100 μg/ml) at pH 7.0, and group methylene blue pH 1 (G-MB/pH 1)-tube filled with fibrin sponge and soaked by methylene blue (100 μg/ml) at pH 1.0. After 7, 15, and 30 days, seven animals from each group were euthanized, and the tubes involved by the surrounding tissue were removed and fixed with 4% buffered formaldehyde solution. The collected pieces were processed and histological sections (4 μm) were stained with hematoxylin and eosin and analyzed by light microscopy. Scores were assigned to analysis of histopathologic parameters. The results were statistically analyzed by the Kruskal-Wallis test (p ≤ 0.05).

RESULTS

At 7 and 30 days, the G-MB/pH 1 group showed no significant difference in the G-T control group, while G-MB/pH 7 had a significant increase on tissue reaction, also when compared to G-T. At 15 days, there was no statistical difference between the groups.

CONCLUSION

Within the limits of this study, it is concluded that methylene blue at pH 1.0 provides better biocompatibility than at pH 7.0.

The effects of photobiomodulation therapy on Staphylococcus aureus infected surgical wounds in diabetic rats. A microbiological, histopathological, and biomechanical study

PURPOSE

To evaluate the effects of photobiomodulation therapy (PBMT) at 685 nm on diabetic wound healing in rats suffering from bacterial infection induced by Staphylococcus aureus (S. aureus).

METHODS

Thirty streptozotocin-induced diabetic rats were allocated into two groups: control and PBMT. A 4-cm full-thickness linear-incision was made on the dorsal midline and was contaminated with S. aureus. The wounds in the PBMT group were irradiated daily for 5 consecutive days, starting 3 days after the induction and always in the mornings.

RESULTS

The result revealed that PBMT resulted in a significant decrease in S. aureus CFU in the PBMT group in comparison to the control group (P<0.05). The length of wounds, in the 2nd and 3rd weeks, in the PBMT group were significantly shorter compared to the control group (P<0.05). PBMT caused a significant increase in the histological parameters in comparison to the control group (P<0.05). Moreover, PBMT significantly increased the breaking strength of the surgical scars produced in the skin of the PBMT group when compared to the control group (P<0.05).

CONCLUSION

Photobiomodulation therapy may be useful in the management of wound infection through a significant bacterial growth inhibition and an acceleration of wound healing process.