The influence of photodynamic therapy on the wound healing process in rats

Treatment of Aphthous Ulcers with Photodynamic Therapy: A Randomized Controlled Clinical Study

BACKGROUND

This study aims to assess whether photodynamic therapy (PDT) offers a clinically effective alternative for treating oral aphthous ulcers, contributing to the ongoing quest for methods to expedite their treatment process amidst the limited understanding of their etiology.

MATERIALS AND METHOD

The study involved thirty volunteers with aphthous ulcers, split equally between a control group and a PDT group. Patients in the PDT group received laser treatment using Indocyanine green upon admission, while the control group received no intervention. Lesion diameter was measured at presentation and on the 3rd, 5th, and 7th days for all patients, with wound healing assessed on the 7th day. Additionally, pain levels were evaluated using the Visual Analog Scale (VAS) preoperatively and on the 1st, 3rd, 5th, and 7th days for the PDT group, and on the corresponding days for the control group.

RESULTS

Lesion diameters in the PDT group showed a significant reduction over time (p=0.001), particularly from preoperative to final measurements. The control group also exhibited a decrease, albeit slower (p=0.001). The 7th-day healing scores favored the PDT group significantly (p=0.012). VAS scores in the PDT group decreased significantly over time (p=0.001), indicating pain reduction. A similar trend was observed in the control group, albeit slower. Between-group differences in healing data and pain data were statistically significant.

CONCLUSION

PDT proves effective in reducing aphthous ulcer diameters and pain intensity, facilitating faster healing than the control group. These results advocate for PDT as a viable treatment option for aphthous lesions.

A new perspective on quantitative assessment of photodynamic therapy mediated hydrogel nanocomposite in wound healing using objective biospeckle and morphological local-gradient

Skin wounding is a serious public health issue, especially when considering factors that accelerate tissue recovery. Consequently, the use of photodynamic therapy (PDT) as an effective wound-healing treatment has attracted more scientific attention. Although assessing the wound healing rate is crucial for appropriate monitoring of the probability of wound healing and evaluating the treatment efficiency, the currently used techniques lack the ability to provide such information. Therefore, this study has two aims, first, it contributes to the development of a new image-guided biospeckle system for quantitative monitoring of skin wound healing rate. Second, it evaluates the potential of using a novel synthesized PDT-mediated polyethylene glycol fabric with methylene blue (PEG-MB) hydrogel nanocomposite in accelerating wound healing. The proposed imaging system initially acquires raw biospeckle images from the wound regions of adult healthy albino mice treated with the synthesized hydrogel nanocomposite. Each raw biospeckle image is then converted into maps of morphological local-gradient matrices implemented from the combination of dilation and erosion operations at different radii up to 25 pixels. Subsequently, their intensity histogram statistics are computed, taking central moments as the feature set. Final characterization is achieved via a linear combination of the biospeckle statistics maintaining as much variance as possible using principal component analysis (PCA). The results confirmed by cytokine concentration measurement and histological investigation demonstrate that the innovative biospeckle image-guided system is ideal for investigating wound healing and suggest the potential of the hydrogel nanocomposite as an active dressing.

5-Aminolevulinic Acid-Mediated Photodynamic Therapy Improves Vocal Fold Wound Healing in Rats

OBJECTIVE

Studies showed that photodynamic therapy (PDT) might be able to prevent vocal fold scar formation when treating laryngeal lesions. We aim to investigate if PDT improves vocal wound healing and reduces scar formation in both prophylactic and remodeling procedures performed in vivo.

STUDY DESIGN

In vivo.

METHODS

Vocal fold stripping was performed in Sprague-Dawley rats. PDT was performed with intraperitoneal injection of 100 mg/kg 5-Aminolevulinic Acid (5-ALA) and 635 nm laser irradiation of 20, 40, and 60 J/cm² . PDT was performed immediately after surgery to study the prophylactic effect and 4 weeks after surgery to study the remodeling effect. Gene expression was evaluated with real-time PCR at 1 week after PDT. Histologic evaluations were performed 12 weeks after PDT, including hematoxylin-eosin, Masson, Alcian blue staining, and immunohistochemical staining of collagen I and III.

RESULTS

PDT induced similar effects on the vocal fold wound healing outcomes in both prophylactic and remodeling procedures. Expression of MMP8, MMP13, HAS2, and TGFβ1 was significantly elevated. Histologic evaluation revealed significantly increased thickness, decreased density of collagen, and increased deposition of hyaluronic acid in the lamina propria. Immunohistochemistry also revealed better distribution and reduced density of collagen I and III. The most obvious changes were seen in the 60 J/cm² PDT group.

CONCLUSION

PDT could significantly improve vocal wound healing by providing both prophylactic effects and remodeling effects. It may be a minimally invasive treatment for vocal fold lesions with slight vocal scarring, and may be used to treat acute or chronic vocal injury to reduce vocal scarring.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:1943-1951, 2023.

Dehydrated Human Amnion/Chorion Membrane Allografts as an Adjunct Wound Healing Therapy in Diabetic Rats

Chronic, non-healing wounds pose a serious public health issue and the need for new treatment methods is paramount. Dehydrated human amnion/chorion membrane has potential wound healing properties, due to the enrichment of growth factors and anti-inflammatory properties. However, its auxiliary advantage on diabetic wounds with demonstrated safety and efficacy in animal models has not been extensively documented. This study aimed at evincing the wound-healing property of dehydrated human amnion chorion membrane in diabetic and non-diabetic rats. An excisional wound model was developed in 36 male Sprague-Dawley rats that were randomly classified into six groups for two experiments. The non-diabetic rat group included non-diabetic control (G1), dHACM treatment (G2), and dHACM dressing + saline-treatment (G3); (n = 6). Similarly, the diabetic group included diabetic control (G4), dHACM treatment (G5), and dHACM dressing + saline-treatment (G6); (n = 6). The results of wound contractility rate, re-epithelialization, grading of granulation tissue, and collagen deposition from histopathological observation demonstrated that in comparison with the other groups (G1, G2, G4, and G5), the animal groups treated with dHACM dressing + saline-treatment (G3 and G6) had superior regenerative effects in excisional wound model. Also, in the animals of G5 and G6 of the diabetic group, there was no statistically significant difference (P > 0.05) in the levels of glucose, urea, creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphate (ALP), when compared to G4 animals during the experiment. It is evident from this study that dHACM could be applied as a potential wound healing biomaterial, especially in diabetic conditions.

Effect of ALA-PDT on inhibition of oral precancerous cell growth and its related mechanisms

BACKROUND

Early treatment of oral precancerous lesions is considered as a key strategy for in oral carcinogenesis prevention. Increasing evidence has suggested that the transforming growth factor beta (TGF-β) signaling pathway is tightly involved in the process of oral-carcinogenesis. In this study, we investigated the inhibition effect and potential mechanism of 5-aminolaevulinic acid photodynamic therapy (ALA-PDT) in human oral precancerous cells via TGF-β pathway.

MATERIALS AND METHODS

Here, the dysplastic oral keratinocyte (DOK) cells were incubated with ALA concentration of 1 mM/mL for 4 h and then irradiated with a Helium-Neon (He-Ne) ion laser at 633 nm (200 mW/cm²). The control cells were cultured in Dulbecco's modified Eagle's medium (DMEM) medium. We analyzed the differentially expressed genes and correlated pathways in oral precancerous cells following ALA-PDT using Affymetrix microarrays. TGF-β pathway was analyzed by quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting. Bioinformatics analysis was performed to evaluate the expression of TGF-β1 in human oral cancer samples and adjacent normal samples. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), flow cytometry, 2'-7'-dichlorodihydrofluorescein diacetate (DCFH-DA), and wound healing assay were used to assess the effects of ALA-PDT plus TGF-β receptor inhibitor (LY2109761) in DOK cells.

RESULTS

The TGF-β signaling could exert in suppressive effects on DOK cells after ALA-PDT. The cell proliferation and migration rate of DOK cells was significantly reduced and apoptosis and ROS generation induced more effectively by ALA-PDT combined with LY2109761. Furthermore, cell cycle analysis revealed that the combined treatment resulted in G0/G1 phase arrest.

CONCLUSIONS

ALA-PDT suppresses the growth of oral precancerous cells by regulating the TGF-β signaling pathway, and its suppressive effect was enhanced using LY2109761. These results indicate that it could be a promising alternative treatment against oral precancerous lesions.

The Effects of Photobiomodulation on Bone Defect Repairing in a Diabetic Rat Model

The purpose of this study is to examine the prospective therapeutic effects of photobiomodulation on the healing of bone defects in diabetic mellitus (DM) using rat models to provide basic knowledge of photobiomodulation therapy (PBMT) during bone defect repair. For in vitro study, an Alizzarin red stain assay was used to evaluate the effect of PBMT on osteogenic differentiation. For in vivo study, micro-computed tomography (microCT) scan, H&E and IHC stain analysis were used to investigate the effect of PBMT on the healing of the experimental calvarial defect (3 mm in diameter) of a diabetic rat model. For in vitro study, the high glucose groups showed lower osteogenic differentiation in both irradiated and non-irradiated with PBMT when compared to the control groups. With the PBMT, all groups (control, osmotic control and high glucose) showed higher osteogenic differentiation when compared to the non-irradiated groups. For in vivo study, the hyperglycemic group showed significantly lower bone regeneration when compared to the control group. With the PBMT, the volume of bone regeneration was increasing and back to the similar level of the control group. The treatment of PBMT in 660 nm could improve the bone defect healing on a diabetic rat calvarial defect model.

The Role of Porphyrinoid Photosensitizers for Skin Wound Healing

Microorganisms, usually bacteria and fungi, grow and spread in skin wounds, causing infections. These infections trigger the immune system and cause inflammation and tissue damage within the skin or wound, slowing down the healing process. The use of photodynamic therapy (PDT) to eradicate microorganisms has been regarded as a promising alternative to anti-infective therapies, such as those based on antibiotics, and more recently, is being considered for skin wound-healing, namely for infected wounds. Among the several molecules exploited as photosensitizers (PS), porphyrinoids exhibit suitable features for achieving those goals efficiently. The capability that these macrocycles display to generate reactive oxygen species (ROS) gives a significant contribution to the regenerative process. ROS are responsible for avoiding the development of infections by inactivating microorganisms such as bacteria but also by promoting cell proliferation through the activation of stem cells which regulates inflammatory factors and collagen remodeling. The PS can act solo or combined with several materials, such as polymers, hydrogels, nanotubes, or metal-organic frameworks (MOF), keeping both the microbial photoinactivation and healing/regenerative processes' effectiveness. This review highlights the developments on the combination of PDT approach and skin wound healing using natural and synthetic porphyrinoids, such as porphyrins, chlorins and phthalocyanines, as PS, as well as the prodrug 5-aminolevulinic acid (5-ALA), the natural precursor of protoporphyrin-IX (PP-IX).

The effect of indocyanine green-mediated photodynamic therapy in healing of experimentally induced oral mucosal traumatic ulcer in rat

Photodynamic therapy (PDT) is a promising approach for the healing of ulcerative lesions. This study aimed to investigate the effect of PDT using indocyanine green (ICG) in the healing of the experimentally induced oral mucosal traumatic ulcer in rat. Sixty adult male Sprague-Dawley rats were recruited in this experimental study. The ulceration was surgically made in the left cheek mucosa, and the rats were randomly assigned into four equal groups (n = 15). Oral ulcers in groups 1 and 2 were treated with the sterile saline solution (0.9%) and ICG (1 mg/ml). In group 3, laser irradiation was applied using the 810 nm diode laser in the continuous-wave mode for 30 s (light dose: 55 J/cm2, power: 300 mW, spot size: 4.5 mm). Following the topical application of ICG (1 mg/ml) in group 4, laser irradiation was performed in the same way as the previous group. After 24 h, treatments were repeated once more in all groups. The healing process was histopathologically assessed at the 3rd, 7th, and 14th days after ulceration. Wound healing was significantly accelerated in the ICG-mediated PDT group in comparison to the control group at all sampling time points (p < 0.005). However, the other groups displayed a similar healing rate (p > 0.05). Data suggest that ICG-mediated PDT has the potential to accelerate wound healing and prevent clinical infection in oral mucosal traumatic ulcers. However, further studies are required to confirm whether our results can be generalized to other wounds.

A massive mandibular keloid with severe infection: What is your treatment?

A case report of massive mandibular keloid with severe infection induced by acne achieved resolution of skin lesions after combined treatment with surgery and high concentration single-dose 5-aminolevulinic acid photodynamic therapy (5-ALA PDT). The patient achieved satisfactory effects, after receiving combined treatment with radiotherapy, secondary healing, intralesional injection of glucocorticoids, and other treatments. The scar didn't exhibit growth in a follow-up check after a year. This case provides evidence that photodynamic therapy is effective in the treatment of massive mandibular keloid with severe infection.

Photodynamic antimicrobial chemotherapy using indocyanine green in experimentally induced intraoral ulcers in rats

BACKGROUND

Photodynamic antimicrobial chemotherapy (PACT) is a promising modality for eradication of microorganisms from the wound. This study aimed to investigate the effectiveness of PACT using indocyanine green (ICG) for reduction of bacterial load of oral ulcers in rats and its impact on the healing process.

METHODS

In this experimental study, 50 adult male Sprague Dawley rats were recruited. Oral ulcers were surgically made on the left cheek mucosa, and animals were randomly assigned into five groups (n = 10). Wound site in groups 1, 2, and 3 was irrigated with the sterile saline (0.9%), chlorhexidine (CHX; 0.2%), and ICG solutions (1 mg/mL), respectively. Group 4 was exposed to laser irradiation using 810 nm diode laser on continuous-wave mode for 30 seconds (fluence: 55 J/cm² , power: 300 mW, spot size: 4.5 mm). In group 5, PACT was performed using topical application of ICG followed by laser irradiation in the same way as the previous group. Bacterial load of oral ulcers was assessed before and after each treatment modality. Besides, rats were sacrificed on the 5th day post ulceration and histological features of healing were evaluated.

RESULTS

Bacterial load was significantly reduced merely in the PACT-ICG-treated group by one log (P < .0001). Animals in the PACT-ICG-treated group also showed an accelerated healing in comparison with others on the 5th day of an experiment.

CONCLUSION

Photodynamic antimicrobial chemotherapy using topical application of ICG has a potential to reduce the bacterial load of oral ulcers and accelerate wound repair. Therefore, it can be considered as an alternative to currently available modalities for wound management.

Photo biostimulatory effect of low dose photodynamic therapy on human mesenchymal stem cells

BACKGROUND

Tissue engineering is one treatment to regenerate bone . Stem cell proliferation or differentiation can be stimulated by adjunctive approaches like photobiomodulation. Some studies suggested that, photodynamic therapy with low concentration of photosensitizers can stimulate cell differentiation as a photobiomodulation approach.

METHODS

Human bone marrow mesenchymal stem cell was isolated and then cultured in sterile medium. Two photosensitizer drugs as 5- aminolevulenic acid (1 mM) (5-ALA) and Methylene blue (1μM) (MB) were used in incubation culture media. In order to activate the photosensitizers, 630 and 660 nm wavelengths were irradiated with 1 J/cm2 energy density, respectively. Cell viability was assessed using MTT assay before and after laser irradiation, and also Alizarin red histologic test was used for calcium nodule formation.

RESULTS

performing the MTT test before irradiation showed that, the optimum concentrations were 1 mM for 5-ALA and 1μM for MB that were optimized. After laser irradiation, ALA group showed no osseous differentiation. In contrast, there was a significant calcium nodule formation in MB group compared with the control one.

CONCLUSIONS

Photodynamic therapy with low photosensitizer concentration and low doses of laser energy density may improve osteogenic differentiation. Accordingly, MB had stimulatory effect on bone marrow derived mesenchymal stem cells. However, 5-ALA did not show this effect.

Effect of photodynamic therapy on the morphological changes of periapical inflammation: An experimental study in rats

AIM

We aimed to explore the morphological changes with photodynamic therapy (PDT) in experimentally produced periapical lesions in rats, and to investigate if PDT used as an adjunct to conventional root canal debridement helps to enhance healing the inflammatory response around root apex of rats.

MATERIALS AND METHODS

Sixty adult Sprague-Dawley male rats (70-90 days/140-160 g) were experimented. Pulp was removed from the mesial root of the first maxillary molar and left open to oral environment to allow the formation of periapical lesion. The rats were numbered and randomly divided into two groups: (i) PDT group (n = 30) received a single session of PDT with conventional debridement and, (ii) Control group (n = 30) received conventional debridement but with no PDT. PDT application involved the use of methylene blue photosensitizer for 5 min inside the root canals and irradiated with diode laser of 805 nm and 20 W power output for 90 s and sealed. After 4 weeks, the experimental rats were sacrificed by cervical dislocation. The maxillary first molar was then collected along with the surrounding tissue for further processing. Hematoxylin and eosin and immunohistochemical staining were used to observe the morphological effects. Proliferating Cell Nuclear Antigen (PCNA), STRO-1 and CD-44 were used as the primary antibodies for the immunohistochemical study.

RESULTS

A reduction in inflammatory cells, which were mainly composed of lymphocytes, was observed in the periapical lesions after PDT. The number of PCNA-positive cells increased to approximately twice in the PDT as compared to the control group. These PCNA-positive cells included STRO-1 and CD-44 positive cells, indicating enhancement of wound healing and reduction in inflammatory cells.

CONCLUSION

The findings of the present experimental study indicate that PDT application induced proliferation of PCNA-positive cells, which included STRO-1 and CD44-positive cells. This suggests that PDT may help to enhance healing periapical lesion, indicating the potential of PDT in the treatment of periapical periodontitis.

An effective zinc phthalocyanine derivative against multidrug-resistant bacterial infection

Bacterial skin and soft tissue infections are abundant worldwide. The rise in the incidence of multidrug-resistant (MDR) bacterial infections has made the need for alternative means of treatment more pressing. We herein report a zinc phthalocyanine derivative, pentalysine [Formula: see text]-carbonylphthalocyanine zinc (ZnPc-(Lys)[Formula: see text] and its strong capability of killing nosocomial MDR bacteria, including MDR-Escherichia coli and MDR-Acinetobacter baumannii. In vitro studies, we observed that ZnPc-(Lys)5 in micromolar concentrations killed above MDR bacteria in 6~6.5 log10 orders with only 5-min illumination of red light at a dosage of 12.75 J/cm[Formula: see text]. Further in vivo studies on a mouse infection model demonstrated that ZnPc-(Lys)5 efficiently inhibited the MDR bacterial growth after one-time photodynamic antibacterial therapy and, interestingly, significantly accelerated the wound healing. Putting together, our findings establish ZnPc-(Lys)5 as a potent antimicrobial candidate for the clinical test on localized infection.

An ex vivo study of photobiostimulation in the treatment of skin pathologies

Photodynamic therapy (PDT) and low level laser therapy (LLLT) may mutually improve the outcomes on the healing process of chronic wounds and other skin pathologies, through processes known to stimulate the proliferation of dermal cellular structures, as well as antimicrobial application. This study proposes the use of nanoemulsion containing aluminium phthalocyanine chloride (ClAlPc) as photosensitizer (PS), to establish the most appropriate protocol for photostimulation in human skin biopsies, associated to type I collagen and elastin production. The combined effect of PS and light (diode laser at 670 nm) at three different doses is compared to the effect of light itself at doses of 70, 140 and 700 mJ ċ cm^-2 , 7 and 14 days after irradiation. Histological analysis reveals the increase in collagen and elastin, higher than 20%, 14 days after treatment with PS and light at 140 mJ ċ cm^-2 . Higher doses of light promote an inhibitory effect, leading to tissue degradation. In addition, the expression levels of the enzymes MMP-2 and MMP-9 (Gelatinases A and B - participant in various processes including tumoral progression and wound healing) are detected by gelatin zymography, reinforcing the efficacy of the combined treatment with PS and light at the intermediate dose.

Animal models for photodynamic therapy (PDT)

Photodynamic therapy (PDT) combines visible light and photosensitizing dyes. Different animal models have been used to test PDT for cancer, infectious disease and cardiovascular disease. Mouse models of tumours include subcutaneous, orthotopic, syngeneic, xenograft, autochthonous and genetically modified.

Photodynamic therapy (PDT) employs non-toxic dyes called photosensitizers (PSs), which absorb visible light to give the excited singlet state, followed by the long-lived triplet state that can undergo photochemistry. In the presence of ambient oxygen, reactive oxygen species (ROS), such as singlet oxygen and hydroxyl radicals are formed that are able to kill cancer cells, inactivate microbial pathogens and destroy unwanted tissue. Although there are already several clinically approved PSs for various disease indications, many studies around the world are using animal models to investigate the further utility of PDT. The present review will cover the main groups of animal models that have been described in the literature. Cancer comprises the single biggest group of models including syngeneic mouse/rat tumours that can either be subcutaneous or orthotopic and allow the study of anti-tumour immune response; human tumours that need to be implanted in immunosuppressed hosts; carcinogen-induced tumours; and mice that have been genetically engineered to develop cancer (often by pathways similar to those in patients). Infections are the second biggest class of animal models and the anatomical sites include wounds, burns, oral cavity, ears, eyes, nose etc. Responsible pathogens can include Gram-positive and Gram-negative bacteria, fungi, viruses and parasites. A smaller and diverse group of miscellaneous animal models have been reported that allow PDT to be tested in ophthalmology, atherosclerosis, atrial fibrillation, dermatology and wound healing. Successful studies using animal models of PDT are blazing the trail for tomorrow's clinical approvals.

Photodynamic therapy relieves colitis and prevents colitis-associated carcinogenesis in mice

BACKGROUND

Inflammatory bowel diseases are incurable illnesses of the gastrointestinal tract, which substantially enhance the risk of developing colorectal carcinogenesis. Conventional photodynamic therapy is a clinically approved therapeutic modality used in the treatment of neoplastic diseases. Recent preclinical and clinical studies have shown that photodynamic therapy with low doses of photosensitizer and/or light improves inflammatory conditions, including colitis. This study aims therefore at investigating the therapeutic potential of low-dose photodynamic therapy (LDPDT) with a liposomal formulation of meta-tetra(hydroxyphenyl)chlorin (namely Foslip) in the prevention of colitis-associated cancer in mice.

METHODS

LDPDT efficacy was evaluated by endoscopic, macroscopic, and histological analysis. Myeloperoxidase levels were quantified by enzyme linked immunosorbent assay and cytokines expression by quantitative RT-PCR analysis. The integrity of the intestinal barrier was evaluated by immunostaining, and bacterial composition of the fecal microbiota was determined by 454 pyrosequencing of V3-V4 region of bacterial 16S rRNA genes.

RESULTS

LDPDT reduced intestinal tumor growth by decreasing the expression of a wide range of inflammatory mediators and by lowering neutrophil influx. LDPDT treatment prevents onset of a dysbiotic microbiota in the colitis-associated cancer model.

CONCLUSIONS

LDPDT with Foslip could be considered as a novel treatment modality to prevent colorectal carcinogenesis in patients with inflammatory bowel disease.

Effect of low-level laser therapy (LLLT) on peripheral nerve regeneration using fibrin glue derived from snake venom

OBJECTIVES

The purpose of this study was to assess whether the adhesive permits the collateral repair of axons originating from a vagus nerve to the interior of a sural nerve graft, and whether low-level laser therapy (LLLT) assists in the regeneration process.

MATERIALS AND METHODS

Study sample consisted of 32 rats randomly separated into three groups: Control Group (CG; n=8), from which the intact sural nerve was collected; Experimental Group (EG; n=12), in which one of the ends of the sural nerve graft was coapted to the vagus nerve using the fibrin glue; and Experimental Group Laser (EGL; n=12), in which the animals underwent the same procedures as those in EG with the addition of LLLT. Ten weeks after surgery, the animals were euthanized. Morphological analysis by means of optical and electron microscopy, and morphometry of the regenerated fibers were employed to evaluate the results.

RESULTS

Collateral regeneration of axons was observed from the vagus nerve to the interior of the autologous graft in EG and EGL, and in CG all dimensions measured were greater and presented a significant difference in relation to EG and EGL, except for the area and thickness of the myelin sheath, that showed significant difference only in relation to the EG.

CONCLUSIONS

The present study demonstrated that the fibrin glue makes axonal regeneration feasible and is an efficient method to recover injured peripheral nerves, and the use of low-level laser therapy enhances nerve regeneration.

Specific features of early stage of the wound healing process occurring against the background of photodynamic therapy using fotoditazin photosensitizer-amphiphilic polymer complexes

There is a growing demand on the studies of the wound healing potentials of photodynamic therapy. Here we analyze the effects of Fotoditazin, an e6 chlorine derivative, and its complexes with amphiphilic polymers, on the early stage of wound healing in a rat model. A skin excision wound model with prevented contraction was developed in male albino rats divided into eight groups according to the treatment mode. All animals received injections of one of the studied compositions into their wound beds and underwent low-intensity laser irradiation or stayed un-irradiated. The clinical monitoring and histological examination of the wounds were performed. It has been found that all the Fotoditazin formulations have significant effects on the early stage of wound healing. The superposition of the inflammation and regeneration was the main difference between groups. The aqueous solution of Fotoditazin alone induced a significant capillary hemorrhage, while its combinations with amphiphilic polymers did not. The best clinical and morphological results were obtained for the Fotoditazin-Pluronic F127 composition. Compositions of Fotoditazin and amphiphilic polymers, especially Pluronic F127, probably, have a great potential for therapy of wounds. Their effects can be attributed to the increased regeneration and suppressed reactions changes at the early stages of repair.

The effectiveness of photodynamic therapy on planktonic cells and biofilms and its role in wound healing

ABSTRACT 

Photodynamic therapy (PDT) is the application of a photoactive dye followed by irradiation that leads to the death of microbial cells in the presence of oxygen. Its use for controlling biofilms has been documented in many areas, particularly oral care. However, the potential use of PDT in the treatment of chronic wound-associated microbial biofilms has sparked much interest in the field of wound care. The aim of this article is to provide an overview on the effectiveness of PDT on in vitro and in vivo biofilms, their potential application in both the prevention and management of wound biofilm infections and their prospective role in the enhancement of wound healing.

Topical photodynamic therapy following excisional wounding of human skin increases production of transforming growth factor-β3 and matrix metalloproteinases 1 and 9, with associated improvement in dermal matrix organization

BACKGROUND

Animal studies report photodynamic therapy (PDT) to improve healing of excisional wounds; the mechanism is uncertain and equivalent human studies are lacking.

OBJECTIVES

To explore the impact of methyl aminolaevulinate (MAL)-PDT on clinical and microscopic parameters of human cutaneous excisional wound healing, examining potential modulation through production of transforming growth factor (TGF)-β isoforms.

METHODS

In 27 healthy older men (60-77 years), a 4-mm punch biopsy wound was created in skin of the upper inner arm and treated with MAL-PDT three times over 5 days. An identical control wound to the contralateral arm was untreated and both wounds left to heal by secondary intention. Wounds were re-excised during the inflammatory phase (7 days, n = 10), matrix remodelling (3 weeks, n = 8) and cosmetic outcome/dermal structure (9 months, n = 9). Production of TGF-β1, TGF-β3 and matrix metalloproteinases (MMPs) was assessed by immunohistochemistry alongside microscopic measurement of wound size/area and clinical assessment of wound appearance.

RESULTS

MAL-PDT delayed re-epithelialization at 7 days, associated with increased inflammation. However, 3 weeks postwounding, treated wounds were smaller with higher production of MMP-1 (P = 0·01), MMP-9 (P = 0·04) and TGF-β3 (P = 0·03). TGF-β1 was lower than control at 7 days and higher at 3 weeks (both P = 0·03). At 9 months, MAL-PDT-treated wounds showed greater, more ordered deposition of collagen I, collagen III and elastin (all P < 0·05).

CONCLUSIONS

MAL-PDT increases MMP-1, MMP-9 and TGF-β3 production during matrix remodelling, ultimately producing scars with improved dermal matrix architecture.

Effect of poly-L-lysine-chlorin P6-mediated antimicrobial photodynamic treatment on collagen restoration in bacteria-infected wounds

OBJECTIVE

The purpose of this work was to study the effect of poly-L-lysine-conjugated chlorin P6 (pl-cp6)-mediated antimicrobial photodynamic treatment (APDT) on collagen remodeling of murine excisional wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO).

BACKGROUND DATA

Bacterial infection of wounds leads to compromised collagen remodelling. APDT-induced inactivation of bacteria and bacterial proteases are expected to restore collagen remodeling in wounds. However, published reports on the effect of PDT on wound healing are somewhat contradictory. One of the reasons for these observations could be the random sampling of wound repair outcomes by invasive technques such as histology.

METHODS

Post-wounding time-dependent changes in collagen restoration were monitored noninvasively using polarization sensitive optical coherence tomography (PSOCT) and compared with histology and hydroxyproline level. Immunoblotting was performed to study matrix metalloproteinase (MMP) level.

RESULTS

As indicated by retardance measurements from PSOCT images and immunoblotting, bacteria-infected wounds showed slower collagen restoration and higher MMP-8, 9 expression, than did uninfected wounds. In contrast, in infected wounds treated with pl-cp6 and light, retardance was higher (approximately twofold) compared with wounds treated with pl-cp6 alone. These results were consistent with lower MMP-8, 9 level on day 5, more ordered collagen matrix, and higher hydroxyproline content (approximately threefold) on day 18, observed in photodynamically treated wounds, compared with that of untreated infected wounds.

CONCLUSIONS

APDT expedites healing in bacteria-infected wounds in mice by attenuating collagen degradation and by enhancing epithelialization, hydroxyproline content, and collagen remodelling.

Foslip®-based photodynamic therapy as a means to improve wound healing

BACKGROUND

Collagen matrices as substitution for connective tissue are known to promote wound healing. Photodynamic therapy has been anecdotally associated with improved wound healing and reduced scarring. The present study investigates the impact of collagen based scaffolding material, embedded with a liposomal formulation of meta-tetra (hydroxyphenyl) chlorin (mTHPC, Foslip(®)) and photodynamic therapy on wound healing in mice.

METHODS

After incision in the neck region, two different types of collagen material, previously incubated with Foslip(®) at different concentrations, were implanted followed by illumination at 652nm (10J/cm(2), 100mW/cm(2)). Mice were imaged daily up to two weeks, whereafter excision was performed and pathological analysis.

RESULTS

Scab detachment was observed at day seven for controls whereas it occurred as early as three days for PDT at the lowest concentrations. In the latter conditions, final matrix remodelling could be observed as evidenced by elastin neosynthesis.

CONCLUSIONS

Topical application of low dose Foslip(®) in a collagen matrix followed by illumination considerably accelerates wound healing.

Laser-induced alveolar bone changes during orthodontic movement: a histological study on rodents

OBJECTIVE

The aim of this study was to assess by light microscopy changes in alveolar bone during orthodontic movement in rats.

BACKGROUND

Orthodontic movement causes both removal and deposition of bone tissue. The use of laser phototherapy (LPT) is considered an enhancement factor for bone repair.

METHODS

Thirty Wistar rats were divided into two groups (n = 15) and subdivided according to animal death (7,13, and 19 days). Half of the animals in each group were treated with LPT during orthodontic movement. After animal death, specimens were processed and underwent histological and semi-quantitative analyses (HE and Sirius red).

RESULTS

LPT-irradiated specimens showed significantly higher numbers of osteoclasts when compared with controls at both 7 (p = 0.015) and 19 (p = 0.007) days, as well as significant increases in the number of osteoblasts (p = 0.015) between days 7 and 13. The amount of collagen matrix was significantly reduced between days 7 and 13 at both pressure and tension sites in controls (p = 0.015) but not in LPT-treated animals. LPT-treated subjects showed significantly greater deposition of collagen matrix at the pressure site at both the thirteenth (p = 0.007) and nineteenth days (p = 0.001). At the tension site, a significant increase in the amount of collagen matrix was observed in non-irradiated specimens (p = 0.048) between days 7 and 19.

CONCLUSIONS

LPT caused significant histological changes in the alveolar bone during induced tooth movement, including alterations in the number of both osteoclasts and osteoblasts and in collagen deposition in both pressure and tension areas.

Efeitos da terapia fotodinâmica e de uma única aplicação de laser de baixa potência em bactérias in vitro

O laser de baixa potência vem sendo usado para acelerar a cicatrização em úlceras de pressão devido a seus efeitos cicatrizante, antiinflamatório, antiedematoso e analgésico. No entanto, não há consenso quanto a seu efeito em úlceras infectadas. O objetivo deste estudo foi verificar o efeito bactericida da laserterapia e da terapia fotodinâmica (TFD) com laser de baixa potência, InGaP, 670 nm, em doses de 2, 4 e 6 J/cm², em bactérias gram-positivas e gram-negativas in vitro. Foram preparadas 32 placas de Petri com bactérias, 16 com Pseudomonas aeruginosa e 16 com Staphilococcus aureus. Aleatoriamente dividiu-se cada grupo em oito subgrupos (duas placas cada): três subgrupos tratados só com laserterapia, em doses de 2 J/cm², 4 J/cm² e 6 J/cm²; três subgrupos tratados com TFD, em doses de 2 J/cm², 4 J/cm² e 6 J/cm²; um tratado apenas com fotossensibilizante (azul de metileno a 0,1 µg/ml); e um subgrupo não tratado (controle). Os subgrupos laser e TFD foram irradiados uma única vez e incubados por 24 horas. Os outros dois subgrupos não receberam irradiação. As culturas foram analisadas visualmente para verificação ou não do halo de inibição. Em todos os subgrupos, de ambas as bactérias, não foi observado qualquer halo de inibição nem de crescimento. Conclui-se que a terapia a laser e a fotodinâmica de baixa potência (InGaP, 670 nm) não produziram efeitos bactericidas e/ou bacteriostáticos, tampouco tendo havido efeito bioestimulante sobre as bactérias.

Photodynamic therapy for Staphylococcus aureus infected burn wounds in mice

The rise of multiply antibiotic resistant bacteria has led to searches for novel antimicrobial therapies to treat infections. Photodynamic therapy (PDT) is a potential candidate; it uses the combination of a photosensitizer with visible light to produce reactive oxygen species that lead to cell death. We used PDT mediated by meso-mono-phenyl-tri(N-methyl-4-pyridyl)-porphyrin (PTMPP) to treat burn wounds in mice with established Staphylococcus aureus infections The third degree burn wounds were infected with bioluminescent S. aureus. PDT was applied after one day of bacterial growth by adding a 25% DMSO/500 microM PTMPP solution to the wound followed by illumination with red light and periodic imaging of the mice using a sensitive camera to detect the bioluminescence. More than 98% of the bacteria were eradicated after a light dose of 210 J cm(-2) in the presence of PTMPP. However, bacterial re-growth was observed. Light alone or PDT both delayed the wound healing. These data suggest that PDT has the potential to rapidly reduce the bacterial load in infected burns. The treatment needs to be optimized to reduce wound damage and prevent recurrence.

Evaluation of the use of low level laser and photosensitizer drugs in healing

BACKGROUND AND OBJECTIVES

In the last decade, many different kinds of therapies have emerged as a consequence of advances in the field of applied technology. It is known that low level laser therapy contributes to tissue healing; however, the use of photodynamic therapy (PDT) in healing and the scar formation processes has not been fully explored. The present study analyses the effect of low level laser InGaAIP (685 nm), radiation, either alone or combined with a phthalocyanine-derived photosensitizer (PS) in a gel base delivery (GB) system, on the healing process of cutaneous wounds in rats.

STUDY DESIGN/MATERIALS AND METHODS

The rats were divided into six groups: control (untreated) (CG), gel base (GB), photosensitizer (PS), laser (LG), laser+photosensitizer (LPS), and laser+photosensitizer in a GB (LPSG). Standardized circular wounds were made on the dorsum of each rat with a skin punch biopsy instrument. After wounding, treatment was performed once daily and the animals were killed at day 8. Tissue specimens containing the whole wound area were removed and processed for histological analysis using conventional techniques. Serial cross-sections were analyzed to evaluate the organization of the dermis and epidermis as well as collagen deposition.

RESULTS

The animals of groups LG, PS, LPS, and LPSG presented higher collagen content and enhanced re-epithelialization as compared to CG (control) and GB rats. Connective tissue remodeling was more evident in groups LPS and LPSG.

CONCLUSIONS

The results clearly indicated a synergetic effect of light+photosensitizer+delivery drug on tissue healing. PDT did not cause any healing inhibition or tissue damage during the healing process.

Rapid control of wound infections by targeted photodynamic therapy monitored by in vivo bioluminescence imaging

The worldwide rise in antibiotic resistance necessitates the development of novel antimicrobial strategies. In this study we report on the first use of a photochemical approach to destroy bacteria infecting a wound in an animal model. Following topical application, a targeted polycationic photosensitizer conjugate between poly-L-lysine and chlorin(e6) penetrated the gram (-) outer bacterial membrane, and subsequent activation with 660 nm laser light rapidly killed Escherichia coli infecting excisional wounds in mice. To facilitate real-time monitoring of infection, we used bacteria that expressed the lux operon from Photorhabdus luminescens; these cells emitted a bioluminescent signal that allowed the infection to be rapidly quantified, using a low-light imaging system. There was a light-dose dependent loss of luminescence in the wound treated with conjugate and light, not seen in untreated wounds. Treated wounds healed as well as control wounds, showing that the photodynamic treatment did not damage the host tissue. Our study points to the possible use of this methodology in the rapid control of wounds and other localized infections.