Low-dose Photodynamic Therapy Research Articles

Skin wound healing in diabetic rat model using low-dose photodynamic therapy.

Chronic wound is one of the major challenges in medicine and imposes a heavy financial burden on the healthcare of different countries. Diabetic foot ulcers as one of the important examples for chronic wounds can lead to lower limb amputation, disability, and death in diabetics. In this regard, novel technology with low side effects got attention in recent years. Low-dose photodynamic therapy (LDPDT) is one of the noninvasive techniques that can be considered for wound healing in diabetic wounds. In this experiment, we aim to study the effect of LDPDT on diabetic rats' wound healing and compare it to healthy rats. In this in vitro experimental study, 32 male rats were used. Rats in both normal and diabetic (streptozotocin injection) groups after being wounded (two wounds [0.8×0.8cm]) on the back of each rat were randomly divided into four groups, including the control group (without treatment), radiation-only (660nm-1 J/cm2 ) group, 5-ALA-only (1µg/mL) group, and LDPDT-recipient group. The procedure has been done for 2days, and at the end of Days 3, 7, 14, and 21, the wound sample was sent to the histopathology laboratory, and the wound size and tissue indices in these groups were evaluated by histology and microscopy techniques. The impact of low concentrations of 5-ALA and low irradiation energy density in both normal and diabetic rats were positive, which accelerated the wound-healing process as seen in the histology study. In diabetic rats treated with only radiation and LDPDT, the process of epithelial regeneration, collagen production, reduction of mast cells, and production of follicles was more as compared to the normal group. The results suggest that LDPDT can have a positive impact on the diabetic rat model wound healing.

Combination of verteporfin-photodynamic therapy with 5-aza-2'-deoxycytidine enhances the anti-tumour immune response in triple negative breast cancer.

Triple negative breast cancer (TNBC) is a subtype of breast cancer characterised by its high tumourigenic, invasive, and immunosuppressive nature. Photodynamic therapy (PDT) is a focal therapy that uses light to activate a photosensitizing agent and induce a cytotoxic effect. 5-aza-2'-deoxycytidine (5-ADC) is a clinically approved immunomodulatory chemotherapy agent. The mechanism of the combination therapy using PDT and 5-ADC in evoking an anti-tumour response is not fully understood. The present study examined whether a single dose of 5-ADC enhances the cytotoxic and anti-tumour immune effect of low dose PDT with verteporfin as the photosensitiser in a TNBC orthotopic syngeneic murine model, using the triple negative murine mammary tumour cell line 4T1. Histopathology analysis, digital pathology and immunohistochemistry of treated tumours and distant sites were assessed. Flow cytometry of splenic and breast tissue was used to identify T cell populations. Bioinformatics were used to identify tumour immune microenvironments related to TNBC patients. Functional experiments showed that PDT was most effective when used in combination with 5-ADC to optimize its efficacy. 5-ADC/PDT combination therapy elicited a synergistic effect in vitro and was significantly more cytotoxic than monotherapies on 4T1 tumour cells. For tumour therapy, all types of treatments demonstrated histopathologically defined margins of necrosis, increased T cell expression in the spleen with absence of metastases or distant tissue destruction. Flow cytometry and digital pathology results showed significant increases in CD8 expressing cells with all treatments, whereas only the 5-ADC/PDT combination therapy showed increase in CD4 expression. Bioinformatics analysis of in silico publicly available TNBC data identified BCL3 and BCL2 as well as the following anti-tumour immune response biomarkers as significantly altered in TNBC compared to other breast cancer subtypes: GZMA, PRF1, CXCL1, CCL2, CCL4, and CCL5. Interestingly, molecular biomarker assays showed increase in anti-tumour response genes after treatment. The results showed concomitant increase in BCL3, with decrease in BCL2 expression in TNBC treatment. In addition, the treatments showed decrease in PRF1, CCL2, CCL4, and CCL5 genes with 5-ADC and 5-ADC/PDT treatment in both spleen and breast tissue, with the latter showing the most decrease. To our knowledge, this is the first study that shows which of the innate and adaptive immune biomarkers are activated during PDT related treatment of the TNBC 4T1 mouse models. The results also indicate that some of the immune response biomarkers can be used to monitor the effectiveness of PDT treatment in TNBC murine model warranting further investigation in human subjects.

Preliminary study of low-dose photodynamic therapy on the oxidative stress response of Cutibacterium acnes

PurposeThe objective of this study was to investigate the influence of photodynamic therapy (PDT) employing different, lower 5-aminolevulinic acid (ALA) dosages on the proliferative activity of Cutibacterium acnes (C. acnes). MethodsIn this in vitro bacterial experiment, we examined the effects of PDT using different doses of ALA (0.05 mmol/L; 0.1 mmol/L; 0.5 mmol/L; 1.0 mmol/L; 2.5 mmol/L). To elucidate the underlying mechanisms, we assessed colony-forming units (CFUs), bacterial staining for live/dead, antioxidant enzyme activity, and gene expression of oxidative stress markers following treatment with different doses of ALA-PDT. ResultsOur findings demonstrate that CFU, bacterial staining for live/dead, as well as the activity and gene expression of superoxide dismutase (SOD) and catalase (CAT), all exhibited significant increases when the ALA concentration was 0.1/0.5 mmol/L. However, both CFU and cell growth of C. acnes decreased when the ALA concentration reached 1.0 mmol/L. ConclusionLower concentration of ALA-PDT (0.1/0.5 mmol/L) appears to promote the growth of C.acnes while higher doses (1.0 /2.5 mmol/L) are associated with eradication. The procedure is possibly mediated by the activation of antioxidant-related genes and enzyme expression in cells.

Bisbenzothieno[b]-fused BODIPYs as efficient near-infrared heavy-atom-free photosensitizers

Fusion thiophene to BODIPY endows the chromophore with more fundamental and special functions. Herein, novel symmetric bisbenzothieno[b]-fused BODIPYs (BTBs) were synthesized and developed. These newly prepared BTB dyes possessed absorption maxima in the range of 643–665 nm, and many outstanding properties including large molar extinction coefficients, and high singlet oxygen generation. Theoretical calculations affirmed that the smaller singlet-triplet energy gap and larger spin−orbit coupling result in efficient intersystem crossing, thus increasing the singlet oxygen generation yield. Notably, Me2NPh-substituted BTB displayed good reactive oxygen species generation efficiency up to 0.41, and a remarkable photo-cytotoxicity (IC50 = 83.5 nM) in HeLa cells, which shows potential in low-dose photodynamic therapy.

A novel chlorin e6 derivative-mediated photodynamic therapy STBF-PDT reverses photoaging via the TGF-β pathway.

Photoaging is characterized by wrinkles in the skin and the deterioration of the skin barrier function, mainly caused by long-term exposure to ultraviolet (UV) radiation. Photodynamic therapy (PDT) has been shown to treat photoaging. The novel photosensitizer ShengTaiBuFen(STBF) is a derived substance of Chlorin e6(Ce6) that can exert photodynamic effects directly. In this study, we investigated the availability and the mechanism of STBF-PDT in the treatment of photoaging. Fluorophotometer was used to determine therapeutic parameters for in vivo experiments. Camera photographs, dermoscopy, HE and Masson staining, skin pH, trans epidermal water loss (TEWL), epidermal water content, and sebum testing were used together to evaluate the results of the treatment. Dark toxicity and therapeutic parameters for in vitro experiments were determined by CCK8 analysis. Scratch assay was used to identify the cell migration of STBF-PDT on HaCaT cells. qPCR and Western blot were used to evaluate the TGF-β/Smad signaling pathway in human dermal fibroblast (HDF) cells. We investigated the optimal STBF concentration and time of incubation in vivo and in vitro experiments. STBF-PDT improved the skin phenotype of photoaged mice. The skin of photoaged mice treated with 80J/cm2 STBF-PDT became smooth, while skin flakes were reduced. The epidermis of STBF-PDT-treated mice was thinner, and the cells were neatly arranged, with increased dermal collagen. In vitro, STBF-PDT promoted the migration of HaCaT cells below a light dose of 0.1J/cm2. HDF cells co-cultured with HaCaT cells treated with low-dose STBF-PDT showed activation of the TGF-β pathway. As a novel photosensitizer, STBF-mediated low-dose PDT could reverse photoaging via the TGF-β pathway.

Quantitative Assessment of Low-Dose Photodynamic Therapy Effects on Diabetic Wound Healing Using Raman Spectroscopy

One of challenges that faces diabetes is the wound healing process. The delayed diabetic wound healing is caused by a complicated molecular mechanism involving numerous physiological variables. Low-dose photodynamic therapy (LDPDT) provides excellent results in rejuvenation and wound healing. In this study, the LDPDT effect on diabetic wounds in mice was studied using two photosensitizers, 5-aminolevulinic acid and methylene blue, and two laser dose expositions of 1 J/cm2 and 4 J/cm2 by Raman spectroscopy (RS). The latter was used as a noninvasive method, providing specific information about tissue state based on the fundamental vibrational modes of its molecular components. RS allows high spatial resolution acquisition of biochemical and structural information through the generation of point spectra or spectral images. An approach to in vivo quantitative assessment of diabetic wound healing state was developed. This approach is based on an application of the principal component analysis combined with the Mahalanobis metrics to skin Raman spectra, in particular, intensities of the amide I and CH2 bands.

Positive effects of low-dose photodynamic therapy with aminolevulinic acid or its methyl ester in skin rejuvenation and wound healing: An update.

In dermatology, photodynamic therapy (PDT) is widely used in skin tumors, infections, etc., because of the killing effect triggered by toxic reactive oxygen species (ROS). However, the ROS concentration is determined by various photosensitizer concentrations and formulations, as well as various irradiation parameters. Low-dose PDT leads to sufficiently low ROS level, which results in biological effects that are the exact opposite of the killing potency. Therefore, in recent years, low-dose PDT has been exploited in improving aging and wound. Low-dose ALA/MAL PDT might improve aging through promoting the proliferation of fibroblasts, blocking DNA damage, counteracting oxidative stress, inhibiting melanogenesis, and remodeling lymphatic vessels in aged skin. Promoting fibroblasts and epidermal stem cells proliferation and migration, promoting granulation tissue formation and angiogenesis and regulating the inflammatory process might be the mechanisms of low-dose ALA/MAL PDT in wound healing. Nevertheless, the positive effects of low-dose PDT have not been thoroughly investigated in dermatology, and high-quality studies are still needed to fill the relevant vacancy.

Nanofibrillar peptide hydrogels for self-delivery of lonidamine and synergistic photodynamic therapy

The use of lonidamine (LND) in photodynamic therapy (PDT) provides a viable approach to develop low-dose PDT modules with high efficacy, for LND potentiates cytotoxicity of photosensitizers through dysregulation of mitochondrial function. Yet, the efficacy of LND is restricted by its low accumulation in cancer cells, especially in the mitochondrial compartments. To address the problem, we design an LND-derived self-assembling peptide molecule (LND-K) that dually targets integrin receptors and mitochondria of cancer cells. The targeted cellular delivery of LND-K gives higher efficacy in ablation of mitochondrial function in melanoma cells A375, as compared to free LND or the control molecule that lacks mitochondria-targeting moieties. To integrate LND-K in a typical PDT module, we develop a nanofibrillar hydrogel system through co-assembly of LND-K and TPPS4, an anionic photosensitizer that forms tight electrostatic interactions with cationic residues of LND-K. Notably, hydrogel formulation of LND-K/TPPS4 facilitates slow release of TPPS4 over 14 days in vitro, and displays a longer retention time than aqueous solution of TPPS4in vivo. By integrating a mitochondria-targeted molecule (LND-K) in a typical PDT module, we achieve synergistic killing of A375 cells with dual drugs, where LND-K not only serves as a chemotherapeutic drug, but also potentiates the cytotoxicities of TPPS4 toward A375 cells in vitro and in vivo. The peptide-based drug self-delivery system promises the development of efficacious combination treatments against cancer, that integrate cell sensitization with existing anticancer modules (e.g., chemotherapy and PDT) for enhanced therapeutic efficacy. Statement of significanceThis study reports the design and synthesis of a lonidamine (LND)-derived self-assembling peptide (LND-K) that dually targets integrin receptors and mitochondria of cancer cells. Under the precision guidance of a mitochondria-targeting sequence, LND-K-containing nanofibers target mitochondria and ablate mitochondrial functions. On one hand, the targeted delivery of LND-K reduces cell viabilities through a chemotherapy route; on the other hand, LND-K sensitizes cancer cells for subsequent PDT treatment with enhanced efficacy, which is mediated by induction of ROS, loss of mitochondrial membrane potential, and decrease of cellular ATP level. We believe that the design of mitochondria-targeted drug delivery systems with a self-assembling molecule provides a new approach to potentiate cytotoxicity of photosensitizers in a low-dose PDT module.

Effects of low-dose photodynamic therapy on the function of human adipose mesenchymal stem cells and its mechanism

Objective: To investigate the effects of low-dose photodynamic therapy on the proliferation, regulation, and secretion functions of human adipose mesenchymal stem cells (ADSCs) and the related mechanism, so as to explore a new method for the repair of chronic wounds. Methods: The experimental research methods were adopted. From February to April 2021, 10 patients (5 males and 5 females, aged 23 to 47 years) who underwent cutaneous surgery in the Department of Dermatology of the First Affiliated Hospital of Army Medical University (the Third Military Medical University) donated postoperative waste adipose tissue. The cells were extracted from the adipose tissue and the phenotype was identified. Three batches of ADSCs were taken, with each batch of cells being divided into normal control group with conventional culture only, photosensitizer alone group with conventional culture after being treated with Hemoporfin, irradiation alone group with conventional culture after being treated with red light irradiation, and photosensitizer+irradiation group with conventional culture after being treated with Hemoporfin and red light irradiation, with sample number of 3 in each group. At culture hour of 24 after the treatment of the first and second batches of cells, the ADSC proliferation level was evaluated by 5-ethynyl-2'-deoxyuridine staining method and the migration percentage of HaCaT cells cocultured with ADSCs was detected by Transwell experiment, respectively. On culture day of 7 after the treatment of the third batch of cells, the extracellular matrix protein expression of ADSCs was detected by immunofluorescence method. The ADSCs were divided into 0 min post-photodynamic therapy group, 15 min post-photodynamic therapy group, 30 min post-photodynamic therapy group, and 60 min post-photodynamic therapy group, with 3 wells in each group. Western blotting was used to detect the protein expressions and calculate the phosphorylated mammalian target of rapamycin complex (p-mTOR)/mammalian target of rapamycin (mTOR), phosphorylated p70 ribosomal protein S6 kinase (p-p70 S6K)/p70 ribosomal protein S6 kinase (p70 S6K) ratio at the corresponding time points after photodynamic therapy. Two batches of ADSCs were taken, and each batch was divided into normal control group, photodynamic therapy alone group, and photodynamic therapy+rapamycin group, with 3 wells in each group. At culture minute of 15 after the treatment, p-mTOR/mTOR and p-p70 S6K/p70 S6K ratios of cells from the first batch were calculated and detected as before. On culture day of 7 after the treatment, extracellular matrix protein expression of cells from the second batch was detected as before. Data were statistically analyzed with one-way analysis of variance and least significant difference test. Results: After 12 d of culture, the cells were verified as ADSCs. At culture hour of 24 after the treatment, the ADSC proliferation level ((4.0±1.0)% and (4.1±0.4)%, respectively) and HaCaT cell migration percentages (1.17±0.14 and 1.13±0.12, respectively) in photosensitizer alone group and irradiation alone group were similar to those of normal control group ((3.7±0.6)% and 1.00±0.16, respectively, P>0.05), and were significantly lower than those of photosensitizer+irradiation group ((34.2±7.0)% and 2.55±0.13, respectively, P<0.01). On culture day of 7 after the treatment, compared with those in normal control group, the expression of collagen Ⅲ in ADSCs of photosensitizer alone group was significantly increased (P<0.05), and the expressions of collagen Ⅰ and collagen Ⅲ in ADSCs of irradiation alone group were significantly increased (P<0.01). Compared with those in photosensitizer alone group and irradiation alone group, the expressions of collagen Ⅰ, collagen Ⅲ, and fibronectin of ADSCs in photosensitizer+irradiation group were significantly increased (P<0.01). Compared with those in 0 min post-photodynamic therapy group, the ratios of p-mTOR/mTOR and p-p70 S6K/p70 S6K of ADSCs in 15 min post-photodynamic therapy group were significantly increased (P<0.01), the ratios of p-p70 S6K/p70 S6K of ADSCs in 30 min post-photodynamic therapy group and 60 min post-photodynamic therapy group were both significantly increased (P<0.01). At culture minute of 15 after the treatment, compared with those in normal control group, the ratios of p-mTOR/mTOR and p-p70 S6K/p70 S6K of ADSCs in photodynamic therapy alone group were significantly increased (P<0.05 or P<0.01). Compared with those in photodynamic therapy alone group, the ratios of p-mTOR/mTOR and p-p70 S6K/p70 S6K of ADSCs in photodynamic therapy+rapamycin group were significantly decreased (P<0.05). On culture day of 7 after the treatment, compared with those in normal control group, the expressions of collagen Ⅰ, collagen Ⅲ, and fibronectin of ADSCs in photodynamic therapy alone group were significantly increased (P<0.01). Compared with those in photodynamic therapy alone group, the expressions of collagen Ⅰ, collagen Ⅲ, and fibronectin of ADSCs in photodynamic therapy+rapamycin group were significantly decreased (P<0.01). Conclusions: Low-dose photodynamic therapy can promote the proliferation of ADSCs, improve the ability of ADSCs to regulate the migration of HaCaT cells, and enhance the secretion of extracellular matrix protein by rapidly activating mTOR signaling pathway.

Fotobiyomodülasyon ve Düşük Doz Fotodinamik Terapinin HUVEC Hücrelerindeki Anjiyogenez'e Yönelik Olası Terapötik Etkileri: Karşılaştırmalı İn Vitro Analiz

Photobiomodulation (PBM) is a non-ionizing therapy that promotes faster wound healing and cell proliferation/differentiation. It is recently understood that photodynamic therapy (PDT) may act as PBM when applied at low-level. In this study, a comparative analysis between PBM and low-dose PDT was performed on HUVECs to increase angiogenesis. HUVECs were irradiated at 808-nm of wavelength. Indocyanine green was used as a photosensitizer in PDT applications. Single and triple treatments were employed for both modalities. Their effects were analyzed with cell viability, intracellular ROS, MMP change, NO release, and morphological analysis. The expressions of vascularization-related proteins (VEGF, PECAM-1, and vWf) were determined through immunofluorescence staining and qRT-PCR. Temperature changes during applications were monitored to determine any thermal damages. It was observed that triple PDT application was more successful at increasing cell proliferation and tube-like structure formation with a 20% rate. The level of ROS did not significantly change in all applications. However, the amount of NO release in triple PDT application was nearly 5 times that of the control group, which showed it acted as a key molecule. The vascularization-related proteins were more strongly expressed in PDT applications. It was understood that low-dose PDT can exert a photobiomodulation effect to accelerate vascularization through NO release.

Photodynamique therapy relieves tumor vascular anergy and promotes immune cell trafficking in an orthotopic mouse model of malignant pleural mesothelioma

Abstract Objective Malignant pleural mesothelioma (MPM) is a deadly disease with limited treatment options. Recently, dual immune checkpoint inhibition therapy (ICI) showed improved patient survival. However, only a fraction of patients were responsive to immunotherapy. One potential mechanism of MPM resistance to ICIs could be their endothelial anergy that hampers leukocyte trafficking to the tumor bulk. Here, we hypothesized that vascular-targeted low dose photodynamic therapy (L-PDT), treatment of MPM could relieve tumor endothelial anergy and improve immunotherapy efficacy. Methods Using an orthotopic syngeneic MPM murine model (AB12 cells injected in the pleura of BALB/c mice), we determined the impact of L-PDT on the endothelial expression of E-Selectin, a key molecule involved in leukocyte diapedesis by immunohistochemistry. Furthermore, to confirm the role of E-selectin, we determined the extravasation of effector T cells (CD8+/CD4+) by immunostaining in L-PDT treated tumors in the presence or absence of an E-selectin blocking antibody. Finally, we assessed tumor growth/survival of our MPM murine model treated with L-PDT alone or combined to ICIs. Results L-PDT pre-treatment enhanced MPM endothelial E-Selectin expression in vivo. The latter was associated with increased CD4+ and CD8+ lymphocyte infiltration of MPM following L-PDT which did not occur after E-Selectin blockade. Also, L-PDT pre-treatment of MPM influenced favorably tumor control, mouse survival and the impact of ICIs compared to controls. Conclusion L-PDT pre-treatment relieves endothelial anergy in MPM which improves antitumor immunity and response to ICI. This approach could constitute a promising pre-treatment option, in combination with ICIs, for the management of this deadly disease.

Synergistic treatment of doxorubicin-resistant breast cancer by the combination of chemotherapy and photodynamic therapy

Drug resistance is the main challenge in cancer treatment by chemotherapy. To overcome the problems, photodynamic therapy (PDT) can be introduced to increase the internalization of chemotherapeutics. Herein, we design and fabricate core-shell nanostructures for the increased therapy effect of drug resistant cancers. Human serum albumin (HSA) is conjugated with Rose Bengal (RB) (HSA-RB) to improve the endocytosis efficiency of the photosensitizer. Then we fabricated a core-shell nanostructure by coating with doxorubicin (DOX)-loaded CaCO3 (CaCO3@DOX) with HSA-RB and dialdehyde carboxymethyl cellulose (DCMC) via a layer-by-layer technique. The formed CaCO3@DOX@(HSA-RB/DCMC)n nanostructures can be easily endocytosed by DOX resistant cancer cells (MCF-7/ADR) in the presence of low dose PDT, and greatly prevent the proliferation of cancer cells by the synergistic effect of PDT and chemotherapy. The nanostructures present efficient methods to solve drug resistance problems in the cure of cancers.

Preliminary low-dose photodynamic exposure to skin cancer with chlorin e6 photosensitizer

BackgroundThe study aimed to investigate the chlorin e6 photosensitizer distribution in the tumor and tumor border (5 mm) during low-dose photodynamic treatment and to increase the effectiveness of the therapy for skin neoplasms. MethodsSensitized boundaries of neoplasms were evaluated by video fluorescence imaging. The study of changes in the chlorin e6 distribution before/after photodynamic therapy and in the process of low-dose photodynamic exposure was carried out by the method of spectral fluorescence diagnostics. ResultsAll 19 patients with basal-cell skin cancer had a contrast of chlorin e6 accumulation compared to normal tissues. 3 hours after intravenous administration of the photosensitizer at a dose of 1 mg/kg, the chlorin e6 concentration was: in normal tissues - 0.18 mg/kg, in the tumor - 1.26 mg/kg, in the tumor border - 0.63 mg/kg. In most cases, the fluorescence indices of chlorin e6 in tumor tissues after low-dose photodynamic therapy increased and exceeded the values before light exposure. ConclusionLow-dose photodynamic therapy seems to be an optimal method for treating select skin neoplasms, which does not cause severe pain in patients during the light exposure and allows for local increase of the photosensitizer concentration in tumor tissues. This method of photodynamic therapy can improve the effectiveness of thе treatment.

The In Vivo Quantitative Assessment of the Effectiveness of Low-Dose Photodynamic Therapy on Wound Healing Using Optical Coherence Tomography.

The effect of low-dose photodynamic therapy on in vivo wound healing was investigated using optical coherence tomography. This work aims to develop an approach to quantitative assessment of the wound’s state during wound healing including the effect of low-dose photodynamic therapy using topical application of two different photosensitizers, 5-aminolevulinic acid and methylene blue, and two laser doses of 1 J/cm2 and 4 J/cm2. It was concluded that the laser dose of 4 J/cm2 was better compared to 1 J/cm2 and allowed the wound healing process to accelerate.

In Vivo Quantification of the Effectiveness of Topical Low-Dose Photodynamic Therapy in Wound Healing Using Two-Photon Microscopy.

The effect of low-dose photodynamic therapy on in vivo wound healing with topical application of 5-aminolevulinic acid and methylene blue was investigated using an animal model for two laser radiation doses (1 and 4 J/cm2). A second-harmonic-generation-to-auto-fluorescence aging index of the dermis (SAAID) was analyzed by two-photon microscopy. SAAID measured at 60–80 μm depths was shown to be a suitable quantitative parameter to monitor wound healing. A comparison of SAAID in healthy and wound tissues during phototherapy showed that both light doses were effective for wound healing; however, healing was better at a dose of 4 J/cm2.

Mechanistic approaches to the light-induced neural cell differentiation: Photobiomodulation vs Low-Dose Photodynamic Therapy

BackgroundNeurodegenerative diseases are the result of irreversible damage in the neuronal cells by effecting vital functions temporarily or even permanently. The use of light for the treatment of these diseases is an emerging promising innovative method. Photobiomodulation (PBM) and Photodynamic Therapy (PDT) are the modalities that have a wide range of use in medicine and have opposite purposes, biostimulation and cell death respectively. MethodsIn this study, we aimed to compare these two modalities (PDT and PBM) at low-level intensities and create a stimulatory effect on the differentiation of PC12 cells. Three different energy densities (1, 3, and 5 J/cm2) were used in PBM and Chlorin e6-mediated PDT applications upon irradiation with 655-nm laser light. The light-induced differentiation profile of PC12 cells was analyzed by morphological examinations, qRT-PCR, cell viability assay, and some mechanistic approaches such as; the analysis of intracellular ROS production, NO release, and mitochondrial membrane potential change. ResultsIt has been observed that both of these modalities were successful at neural cell differentiation. PBM at 1 J/cm2 and low-dose PDT at 3 J/cm2 energy densities provided the best differentiation profiles which were proved by the over-expressions of SYN-1 and GAP43 genes. It was also observed that intracellular ROS production and NO release had pivotal roles in these mechanisms with more cell differentiation obtained especially in low-dose PDT application. ConclusionIt can be concluded that light-induced mechanisms with properly optimized light parameters have the capacity for neural cell regeneration and thus, can be a successful treatment for incurable neurodegenerative diseases.

Effect of low-dose PDT on perfusion of the choriocapillaris in cCSCR : An OCT-angiography-based study

In patients with chronic central serous chorioretinopathy (cCSCR) it is assumed that low-dose photodynamic therapy (PDT) induces short-term hypoperfusion of the choriocapillaris, which leads to long-term choroidal vascular remodeling and subsequent reduction of vascular hyperpermeability and leakage; however, it remains unclear whether the hypoperfusion completely returns to normal. The main aim of the retrospective study was to analyze the choroidal flow signal after treatment with low-dose PDT by optical coherence tomography-angiography (OCT‑A). In this study 16eyes with atotal of 19treated areas were included. Aside from visual acuity and metamorphopsia checks, all patients underwent enhanced depth imaging-OCT (EDI-OCT) and OCT‑A in the areas treated with low-dose PDT. In the present study, the flow signal in the choriocapillaris and choroidal thickness were measured retrospectively both in the PDT-treated area and in anon-treated reference area located in close proximity with similar eccentricity to the center of the fovea. The study found amean reduction of 33% (p < 0.001) of the choroidal flow signal in the treated area compared to the reference area and an average decrease in choroidal thickness of 71 µm (p = 0.001). In the long term 7out of 10patients suffered from metamorphopsia despite the low-dose PDT; however, visual acuity was improved in almost half of the patients by the treatment. Using OCT‑A it could be shown that at the choriocapillaris level, hypoperfusion persists in spite of low-dose PDT. Thus, the choroidal vascular remodeling is not able to completely compensate for the hypoperfusion induced by thrombosis.

Inhibiting autophagy increases the efficacy of low-dose photodynamic therapy

Rupture and permeabilization of endocytic vesicles can be triggered by various causes, such as pathogenic invasions, amyloid proteins, and silica crystals leading to cell death and degeneration. A cellular quality control process, called lysophagy was recently described to target damaged lysosomes for autophagic sequestration within isolation membranes in order to protect the cell from the consequences of lysosomal leakage. This protective process, however, might interfere with treatment conditions, such as photodynamic therapy (PDT) and the intracellular drug delivery method photochemical internalization (PCI). PCI-induced permeabilization of endosomes and lysosomes is purposely triggered to release drugs that are sequestered in these organelles into the cytosol in order to synergistically kill cancer cells. Here, we show that photochemical treatment with the PCI-photosensitizer TPCS2a/fimaporfin results in both induction of autophagy and inhibition of the autophagic flux. The autophagic response is accompanied by recruitment of ubiquitin (Ubq), p62, and microtubule-associated protein 1A/1B-light chain 3 (LC3) to damaged vesicles, marked by Galectin 3 (Gal3). Furthermore, ultrastructural analysis revealed a homogenously thick p62-positive layer surrounding these permeabilized vesicles. Although p62 seems to be important during the selective autophagic sequestration, we show that its presence is not essential for the effective removal of damaged vesicles or the recovery of the lysosomal content. An active autophagic response and the presence of p62, however, is important for cancer cells to survive low-dose TPCS2a-PDT. Thus, targeting both p62 and autophagy together and independently, in a light-controlled/PCI based delivery of cancer therapeutics could increase the effectiveness of the treatment regime.

Abstracts from the World Federation for Laser Dentistry—Asia Pacific Division Virtual Conference July 16–17, 2021

Abstracts from the World Federation for Laser Dentistry—Asia Pacific Division Virtual Conference July 16–17, 2021

Low-dose photodynamic therapy effect on closure of scratch wounds of normal and diabetic fibroblast cells: An in vitro study.

Chronic wounds such as diabetic ulcers are a serious public health problem. Extensive research is needed to find new alternatives for wound treatment. Photodynamic therapy (PDT) is a non-invasive method, which has been studied for several decades to treat cancer, infections, and other diseases. PDT involves the administration of a photosensitizer compound followed by irradiation with using light at specific wavelength to produce reactive oxygen species (ROS) using molecular oxygen. It is possible that low dose photodynamic therapy (LDPDT) could improve wound healing and stimulates the cell repair process. This study we explored the effect of LDPDT on wound healing in vitro using normal and diabetic cellular wound models. The effects of different concentrations of 5-ALA and different energy densities (dark or light) on the cell viability of human fibroblast cells were studied using the MTT assay. After ascertaining the optimum parameters, a scratch wound assay was performed on both normal and diabetic cells and then cells treated with 1 and 5μg/mL of 5-ALA at 1J/cm2 energy density. ROS production and morphological alteration of the cells were studied. The mortality of normal fibroblast cells increased with increasing 5-ALA concentration and also increasing energy density (up to 3J/cm2 ). However, in diabetic cells, the mortality rate did not decrease. Diabetic cells showed increased migration and closure of the scratch compared to normal cells under similar conditions. A low concentration of 5-ALA (5μg/mL) and low energy density of 1J/cm2 in both normal and diabetic cells gave a small increase in ROS levels compared to controls. This may explain the positive effects of LDPDT on wound healing. The findings of this study suggest that LDPDT may have a potential effect on the wound healing of diabetic wounds.