Methylene blue-mediated photodynamic therapy enhances apoptosis in lung cancer cells

One-pot synthesis and covalent conjugation of methylene blue in mesoporous silica nanoparticles - A platform for enhanced photodynamic therapy

Photodynamic therapy (PDT) is an emerging clinical modality for diverse disease conditions, including cancer. This technique involves, the generation of cytotoxic reactive oxygen species by a photosensitizer in the presence of light and oxygen. Methylene blue (MB) is a cationic dye with an ability to act as photosensitizing and bioimaging agent. The direct utilization of MB as photosensitizer for biological applications has often been impeded by its poor photostability and unwanted tissue interactions. Nanocarriers such as mesoporous silica nanoparticles (MSNs) provide an effective means of overcoming these limitations. However, the mere physical adsorption of the dye within the MSN can result in leakage, compromising the effectiveness of PDT. Therefore, in this work, we report the conjugation of MB into MSNs using novel MB-silane derivatives, namely MBS1 and MBS2, to create dye-doped and amine-functionalized MSNs (MBS1-AMSN and MBS2-AMSN). The PDT efficacy and bioimaging capability of these nanoparticles were compared with those of MSNs in which MB was non-covalently encapsulated (MB@AMSN). The synthesized nanoparticles, ultra-small in size (≤ 35 ± 4 nm) with monodispersity, exhibited enhanced fluorescence quantum yields. MBS1-AMSN demonstrated 70-fold increase, while MBS2-AMSN showed 33-fold improvement in fluorescence quantum yields compared to MB@AMSN at the same concentration. Covalent conjugation resulted in a 2-fold enhancement in the singlet oxygen quantum yield of the dye in MBS1-AMSN and 1.2-fold improvement in MBS2-AMSN, compared to non-covalent encapsulation. Assessment on RAW 264.7 macrophages revealed superior fluorescence in cell imaging for MBS1-AMSN, establishing it as a more efficient PDT agent compared to MBS2-AMSN and MB@AMSN. These findings suggest that MBS1-AMSN holds significant potential as a theranostic nanoplatform for image-guided PDT.

Mucoadhesive liquid crystal precursor system for photodynamic therapy of oral cancer mediated by methylene blue

Oral cancer is one of the most prevalent types of cancer head and neck cancers worldwide. Photodynamic therapy (PDT) has demonstrated great potential against cancers, reducing long-term morbidity. In this study, we investigated the incorporation of methylene blue (MB) in a mucoadhesive liquid crystal precursor system (LCPS) for oral cancer treatment. The photostability and the in vitro release, permeation, and retention profile of MB-loaded LCPS (MB-LCPS) were investigated, as well as its in vitro PDT activity against normal (HaCaT) and tumoral (HSC-3) cell lines. LCPS increased the photostability of MB and exhibited a prolonged release profile of MB. In addition, LCPS increased the retention of MB in the porcine esophageal mucosa by around 3 times higher than the MB solution. The retention of MB in LCPS was around 2 times greater than its permeability, which is suitable for guaranteeing the maintenance of the therapy in the oral cavity. In vitro cytotoxicity assay indicated that MB-LCPS increased the antitumoral activity of MB after 20 min of irradiation at 660 nm and 12.5 J/cm2. The results obtained suggest that the developed formulation is an interesting strategy for the potential application in the treatment of oral cancer by PDT.

Photodynamic therapy reduces cell viability, migration and triggers necroptosis in prostate tumor cells

Prostate cancer is the most common cancer in American men, aside from skin cancer. As an alternative cancer treatment, photodynamic laser therapy (PDT) can be used to induce cell death. We evaluated the PDT effect, using methylene blue as a photosensitizer, in human prostate tumor cells (PC3). PC3 were subjected to four different conditions: DMEM (control); laser treatment (L-660 nm, 100 mW, 100 J.cm^-2); methylene blue treatment (MB-25 μM, 30 min), and MB treatment followed by low-level red laser irradiation (MB-PDT). Groups were evaluated after 24 h. MB-PDT treatment reduced cell viability and migration. However, because MB-PDT did not significantly increase the levels of active caspase-3 and BCL-2, apoptosis was not the primary mode of cell death. MB-PDT, on the other hand, increased the acid compartment by 100% and the LC3 immunofluorescence (an autophagy marker) by 254%. Active MLKL level, a necroptosis marker, was higher in PC3 cells after MB-PDT treatment. Furthermore, MB-PDT resulted in oxidative stress due to a decrease in total antioxidant potential, catalase levels, and increased lipid peroxidation. According to these findings, MB-PDT therapy is effective at inducing oxidative stress and reducing PC3 cell viability. In such therapy, necroptosis is also an important mechanism of cell death triggered by autophagy.

Phototherapeutic Induction of Immunogenic Cell Death and CD8+ T Cell-Granzyme B Mediated Cytolysis in Human Lung Cancer Cells and Organoids

Augmenting T cell mediated tumor killing via immunogenic cancer cell death (ICD) is the cornerstone of emerging immunotherapeutic approaches. We investigated the potential of methylene blue photodynamic therapy (MB-PDT) to induce ICD in human lung cancer. Non-Small Cell Lung Cancer (NSCLC) cell lines and primary human lung cancer organoids were evaluated in co-culture killing assays with MB-PDT and light emitting diodes (LEDs). ICD was characterised using immunoblotting, immunofluorescence, flow cytometry and confocal microscopy. Phototherapy with MB treatment and low energy LEDs decreased the proliferation of NSCLC cell lines inducing early necrosis associated with reduced expression of the anti-apoptotic protein, Bcl2 and increased expression of ICD markers, calreticulin (CRT), intercellular cell-adhesion molecule-1 (ICAM-1) and major histocompatibility complex I (MHC-I) in NSCLC cells. MB-PDT also potentiated CD8+ T cell-mediated cytolysis of lung cancer via granzyme B in lung cancer cells and primary human lung cancer organoids.

Evaluation of photodynamic therapy against Leishmania tropica promastigotes using different photosensitizers

BACKGROUND

Photodynamic therapy is a two-step procedure, involving the use of photosensitizing agents followed by selective illumination of the target lesion with visible light. Photodynamic therapy has been described recently as a promising strategy for treatment of leishmaniasis. This study aims to evaluate the in vitro phototoxic, morphological, and apoptotic effect of methylene blue, toluidine blue, chloro-aluminum phthalocyanine, and pheophorbide a-mediated photodynamic therapy on the viability of Leishmania tropica promastigotes.

METHODS

Parasites were treated with methylene blue, toluidine blue, chloro-aluminum phthalocyanine, and pheophorbide a or/and methylene blue, toluidine blue, chloro-aluminum phthalocyanine, and pheophorbide a-mediated photodynamic therapy, and cell proliferation, morphological changes, and apoptosis were evaluated by XTT, giemsa staining, DAPI staining, and DNA fragmentation, respectively.

RESULTS

Parasite viability was significantly different in between the groups treated with methylene blue, toluidine blue, and pheophorbide a, with or without irradiation. chloro-aluminum phthalocyanine treatment did not lead to any alterations in cell viability in Leishmania tropica promastigotes with or without irradiation. DAPI staining results indicated that apoptotic bodies and nucleus fragmentation started to be visible in methylene blue, chloro-aluminum phthalocyanine, and pheophorbide a-mediated photodynamic therapy groups. DNA ladder pattern which is used to define apoptosis was observed in irradiated methylene blue, chloro-aluminum phthalocyanine, and pheophorbide a groups.

CONCLUSIONS

The results revealed that apoptosis-induced cell death was observed in Leishmania tropica promastigotes after the application of photosensitizers in combination with light irradiation.

The Potentials of Methylene Blue as an Anti-Aging Drug

Methylene blue (MB), as the first fully man-made medicine, has a wide range of clinical applications. Apart from its well-known applications in surgical staining, malaria, and methemoglobinemia, the anti-oxidative properties of MB recently brought new attention to this century-old drug. Mitochondrial dysfunction has been observed in systematic aging that affects many different tissues, including the brain and skin. This leads to increaseding oxidative stress and results in downstream phenotypes under age-related conditions. MB can bypass Complex I/III activity in mitochondria and diminish oxidative stress to some degree. This review summarizes the recent studies on the applications of MB in treating age-related conditions, including neurodegeneration, memory loss, skin aging, and a premature aging disease, progeria.

Methylene blue and photodynamic therapy for melanomas: Inducing different rates of cell death (necrosis and apoptosis) in B16-F10 melanoma cells according to methylene blue concentration and energy dose

BACKGROUND

Photodynamic therapy (PDT) is a cancer treatment based on the interaction between the photosensitizing agent methylene blue (MB), light, and molecular oxygen. MB has antibacterial properties and can to bind to melanin. Here, we investigated whether MB combined with PDT (MB-PDT) could decrease viability and induce death of murine melanoma B16-F10 cells.

METHODS

B16-F10 cells were incubated with different concentrations of MB (0, 1, or 2 µg/mL) and exposed to a diode red laser with a wavelength of 660 nm and power output of 100 mW/cm². The energy dose and density varied from 0 J and 0 J/cm² to 100.8 J and 720 J/cm². Cell viability was measured using the trypan blue exclusion assay of cell viability and confirmed by performing an MTT assay. The morphological type and cell death rates were determined using fluorescence microscopy with acridine orange and ethidium bromide. The presence and rate of apoptosis were evaluated via Annexin V-Alexa Fluor/propidium iodide staining and flow cytometry analysis.

RESULTS

MB-PDT decreased cell viability and increased cell death (necrosis and apoptosis) in a drug- and light-dose dependent manner. Morphological characteristics of necrosis were observed immediately after treatment, and apoptotic characteristics were observed after 3 h. The apoptosis and necrosis rates varied with the drug and light doses, with 2 µg/mL MB and a 100.8 J energy dose inducing the highest rates.

CONCLUSIONS

We demonstrated that MB-PDT reduced murine melanoma B16-F10 cell viability and induced cell death in a drug- and light-dose dependent manner.

Methylene Blue-Based Nano and Microparticles: Fabrication and Applications in Photodynamic Therapy

Methylene blue (MB) has been used in the textile industry since it was first extracted by the German chemist Heinrich Caro. Its pharmacological properties have also been applied toward the treatment of certain diseases such as methemoglobinemia, ifosfamide-induced encephalopathy, and thyroid conditions requiring surgery. Recently, the utilization of MB as a safe photosensitizer in photodynamic therapy (PDT) has received attention. Recent findings demonstrate that photoactivated MB exhibits not only anticancer activity but also antibacterial activity both in vitro and in vivo. However, due to the hydrophilic nature of MB, it is difficult to create MB-embedded nano- or microparticles capable of increasing the clinical efficacy of the PDT. This review aims to summarize fabrication techniques for MB-embedded nano and microparticles and to provide both in vitro and in vivo examples of MB-mediated PDT, thereby offering a future perspective on improving this promising clinical treatment modality. We also address examples of MB-mediated PDT in both cancer and infection treatments. Both in-vitro and in-vivo studies are summarized here to document recent trends in utilizing MB as an effective photosensitizer in PDT. Lastly, we discuss how developing efficient MB-carrying nano- and microparticle platforms would be able to increase the benefits of PDT.

Catalytically Active CoFe2O4 Nanoflowers for Augmented Sonodynamic and Chemodynamic Combination Therapy with Elicitation of Robust Immune Response

A hypoxic and acidic tumor microenvironment (TME) plays a significant role in cancer development through complex cellular signaling networks, and it is thus challenging to completely eradicate tumors via monotherapy. Here, PEGylated CoFe₂O₄ nanoflowers (CFP) with multiple enzymatic activities, serving as bioreactors responsive to TME cues, were synthesized via a typical solvothermal method for augmented sonodynamic therapy (SDT) and chemodynamic therapy (CDT) with elicitation of robust immune response. The CFP occupying multivalent elements (Co^2+/3+, Fe^2+/3+) exhibited strong Fenton-like and catalase-like activity. In another aspect, CFP itself is a brand-new sonosensitizer for high-performance SDT based on ultrasound-triggered electron (e^-)/hole (h⁺) pair separation from the energy band with promptness and high efficiency. With efficient enrichment in tumorous tissue as revealed by magnetic resonance imaging, CPF could generate ^•OH for CDT relying on Fenton-like reactions. Moreover, catalase-mimicking CFP could react with endogenous H₂O₂ to generate molecular oxygen, and high O₂ level may promote the production of ¹O₂ for SDT. What's more, the reactive oxygen species obtained from combined SDT/CDT could efficiently trigger immunogenic cell death through a synergistic therapy based on the elicitation of antitumor immunity with the aid of an immune checkpoint blockade for the sake of suppressing primary and distant tumors as well as lung metastasis. Taken together, this paradigm delivers useful insights for developing in-coming nanocomposites based on cobalt ferrite for cancer theranostics.

Graphene-based nanomaterials for breast cancer treatment: promising therapeutic strategies

Breast cancer is the most common malignancy in women, and its incidence increases annually. Traditional therapies have several side effects, leading to the urgent need to explore new smart drug-delivery systems and find new therapeutic strategies. Graphene-based nanomaterials (GBNs) are potential drug carriers due to their target selectivity, easy functionalization, chemosensitization and high drug-loading capacity. Previous studies have revealed that GBNs play an important role in fighting breast cancer. Here, we have summarized the superior properties of GBNs and modifications to shape GBNs for improved function. Then, we focus on the applications of GBNs in breast cancer treatment, including drug delivery, gene therapy, phototherapy, and magnetothermal therapy (MTT), and as a platform to combine multiple therapies. Their advantages in enhancing therapeutic effects, reducing the toxicity of chemotherapeutic drugs, overcoming multidrug resistance (MDR) and inhibiting tumor metastasis are highlighted. This review aims to help evaluate GBNs as therapeutic strategies and provide additional novel ideas for their application in breast cancer therapy.

Co-Encapsulation of Methylene Blue and PARP-Inhibitor into Poly(Lactic-Co-Glycolic Acid) Nanoparticles for Enhanced PDT of Cancer

The development of resistance against photodamage triggered by photodynamic therapy (PDT) is ascribed mainly to the cellular redox defenses and repair. If the tumor tissue is not promptly eliminated by the first few PDT sessions, PDT-resistance can be favored, challenging the efficacy of the treatment. Although the mechanism of PDT resistance is still unclear, in vitro assays have evidenced that it can be developed through the PARP damage-repair signaling pathway. Therefore, inhibition of poly(adenosine diphosphate (ADP)-ribose) polymerase (PARP) has the potential to increase PDT efficacy. This work reports on the synthesis of a controlled release system of a photosensitizer, methylene blue (MB) and a PARP-inhibitor, the veliparib. MB and veliparib were co-encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (VMB-NPs). A colloidal stable aqueous suspension of nanoparticles was obtained. The average hydrodynamic diameter was 90 nm and a narrow size distribution was obtained, with a polydispersity index (PDI) of 0.08. The release kinetics of MB and veliparib from VMB-NPs showed an initial burst of 8.7% and 58.3% release of the total amounts of MB and veliparib respectively, in the first 6 h, and a delayed release of up to 11.3% and 70%, in 19 days, for MB and veliparib, respectively. The VMB-NPs showed no cytotoxicity in the dark but the viability of B16F10-Nex2 cells decreased by 36% when the cells were irradiated (102 J/cm², 660 nm) and treated with VMB-NPs containing 1.0 µM of MB and 8.3 µM of veliparib. Considering the increased photoactivity even at low MB and veliparib concentrations and the absence of cytotoxicity in dark, the co-encapsulation of MB and veliparib was shown to be a promising strategy to improve the PDT efficacy.

The photosensitiser azure A disrupts mitochondrial bioenergetics through intrinsic and photodynamic effects

Azure A (AA) is a cationic molecule of the class of phenothiazines that has been applied in vitro as a photosensitising agent in photodynamic antimicrobial chemotherapy. It is a di-demethylated analogue of methylene blue (MB), which has been demonstrated to be intrinsically and photodynamically highly active on mitochondrial bioenergetics. However, as far as we know, there are no studies about the photodynamic effects of AA on mammalian mitochondria. Therefore, this investigation aimed to characterise the intrinsic and photodynamic acute effects of AA (0.540 μM) on isolated rat liver mitochondria, isolated hepatocytes, and isolated perfused rat liver. The effects of AA were assessed by evaluating several parameters of mitochondrial bioenergetics, oxidative stress, cell viability, and hepatic energy metabolism. The photodynamic effects of AA were assessed under simulated hypoxic conditions, a suitable way for mimicking the microenvironment of hypoxic solid tumour cells. AA interacted with the mitochondria and, upon photostimulation (10 min of light exposure), produced toxic amounts of reactive oxygen species (ROS), which damaged the organelle, as demonstrated by the high levels of lipid peroxidation and protein carbonylation. The photostimulated AA also depleted the GSH pool, which could compromise the mitochondrial antioxidant defence. Bioenergetically, AA photoinactivated the complexes I, II, and IV of the mitochondrial respiratory chain and the F1FO-ATP synthase complex, sharply inhibiting the oxidative phosphorylation. Upon photostimulation (10 min of light exposure), AA reduced the efficiency of mitochondrial energy transduction and oxidatively damaged lipids in isolated hepatocytes but did not decrease the viability of cells. Despite the useful photobiological properties, AA presented noticeable dark toxicity on mitochondrial bioenergetics, functioning predominantly as an uncoupler of oxidative phosphorylation. This harmful effect of AA was evidenced in isolated hepatocytes, in which AA diminished the cellular ATP content. In this case, the cells exhibited signs of cell viability reduction in the presence of high AA concentrations, but only after a long time of incubation (at least 90 min). The impairments on mitochondrial bioenergetics were also clearly manifested in intact perfused rat liver, in which AA diminished the cellular ATP content and stimulated the oxygen uptake. Consequently, gluconeogenesis and ureogenesis were strongly inhibited, whereas glycogenolysis and glycolysis were stimulated. AA also promoted the release of cytosolic and mitochondrial enzymes into the perfusate concomitantly with inhibition of oxygen consumption. In general, the intrinsic and photodynamic effects of AA were similar to those of MB, but AA caused some distinct effects such as the photoinactivation of the complex IV of the mitochondrial respiratory chain and a diminution of the ATP levels in the liver. It is evident that AA has the potential to be used in mitochondria-targeted photodynamic therapy, even under low oxygen concentrations. However, the fact that AA directly disrupts mitochondrial bioenergetics and affects several hepatic pathways that are linked to ATP metabolism, along with its ability to perturb cellular membranes and its little potential to reduce cell viability, could result in significant adverse effects especially in long-term treatments.

Effect of photodynamic therapy on expression of HRAS, NRAS and caspase 3 genes at mRNA levels, apoptosis of head and neck squamous cell carcinoma cell line

OBJECTIVES

This study aimed to assess the effect of photodynamic therapy (PDT) on expression of CASP3, NRAS and HRAS genes at mRNA levels, and apoptosis of head and neck squamous cell carcinoma (HNSCC) cell line.

MATERIALS AND METHODS

In order to complete the present in vitro study, HNSCC cell line (NCBI C196 HN5) purchased from Pasteur Institute. Cells were divided into four groups; Group 1: photodynamic treatment (laser + methylene blue (MB) as photosensitizer), group 2: MB, group 3: laser (with 660 nm wavelength), and group 4: control (without any treatment). To determine the optimal concentration of MB, in a pilot study, toxicity of MB in different concentration was assessed using MTT assay. Cells in group 1, 2 and 3 was treated at optimal concentration of MB (1.6 μg/mL). Gene expression at mRNA levels was assessed after 24 h incubation, using real-time (qRT)-PCR. The expression of BAX and BCL2 genes at the mRNA levels was analyzed to evaluate apoptosis. 2^-ΔΔCt values of BCL2, BAX, CASP3, NRAS, and HRAS in groups was analyzed using ANOVA. Tukey's HSD and Games Howell test was used to compare between two groups.

RESULTS

Over-expression of BAX (p < 0.001), CASP3 (p < 0.001) and down-regulation of BCL2 (p = 0.004), HRAS (p = 0.023) and NRAS (p = 0.045) were noted in group 1 (PDT), compared with the control group. Treatment by laser alone induce down-regulation of CASP3 (p < 0.05), BAX (p < 0.05), BCL2 (p > 0.05), HRAS (p > 0.05) and NRAS (p > 0.05).

CONCLUSION

PDT caused down-regulation of NRAS, HRAS and BCL2 and over-expression of CASP3 and BAX genes at mRNA levels in HNSCC cell line. The present study raises the possibility that the role of MB on BCL2 down-regulation and BAX and CASP3 over-expression was higher than laser alone while it seems that laser alone was more effective than MB in HRAS and NRAS down-regulation.

A decision process for drug discovery in retinoblastoma

Intraocular retinoblastoma treatment has changed radically over the last decade, leading to a notable improvement in ocular survival. However, eyes that relapse remain difficult to treat, as few alternative active drugs are available. More challenging is the scenario of central nervous system (CNS) metastasis, in which almost no advancements have been made. Both clinical scenarios represent an urgent need for new drugs. Using an integrated multidisciplinary approach, we developed a decision process for prioritizing drug selection for local (intravitreal [IVi], intrathecal/intraventricular [IT/IVt]), systemic, or intra-arterial chemotherapy (IAC) treatment by means of high-throughput pharmacological screening of primary cells from two patients with intraocular tumor and CNS metastasis and a thorough database search to identify clinical and biopharmaceutical data. This process identified 169 compounds to be cytotoxic; only 8 are FDA-approved, lack serious toxicities and available for IVi administration. Four of these agents could also be delivered by IT/IVt. Twelve FDA-approved drugs were identified for systemic delivery as they are able to cross the blood-brain barrier and lack serious adverse events; four drugs are of oral usage and six compounds that lack vesicant or neurotoxicity could be delivered by IAC. We also identified promising compounds in preliminary phases of drug development including inhibitors of survivin, antiapoptotic Bcl-2 family proteins, methyltransferase, and kinesin proteins. This systematic approach may be applied more broadly to prioritize drugs to be repurposed or to identify novel hits for use in retinoblastoma treatment.

Molecular interaction and cellular studies on combination photodynamic therapy with rutoside for melanoma A375 cancer cells: an in vitro study

Background

Melanoma as a type of skin cancer, is associated with a high mortality rate. Therefore, early diagnosis and efficient surgical treatment of this disease is very important. Photodynamic therapy (PDT) involves the activation of a photosensitizer by light at specific wavelength that interacts with oxygen and creates singlet oxygen molecules or reactive oxygen species (ROS), which can lead to tumor cell death. Furthermore, one of the main approches in the prevention and treatment of various cancers is plant compounds application. Phenolic compounds are essential class of natural antioxidants, which play crucial biological roles such as anticancer effects. It was previously suggested that flavonoid such as rutoside could acts as pro-oxidant or antioxidant. Hence, in this study, we aimed to investigate the effect of rutoside on the combination therapy with methylene blue (MB) assisted by photodynamic treatment (PDT) using red light source (660 nm; power density: 30 mW/cm²) on A375 human melanoma cancer cells.

Methods

For this purpose, the A375 human melanoma cancer cell lines were treated by MB-PDT and rutoside. Clonogenic cell survival, MTT assay, and cell death mechanisms were also determined after performing the treatment. Subsequently, after the rutoside treatment and photodynamic therapy (PDT), cell cycle and intracellular reactive oxygen species (ROS) generation were measured.

Results

The obtained results showed that, MB-PDT and rutoside had better cytotoxic and antiprolifrative effects on A375 melanoma cancer cells compared to each free drug, whereas the cytotoxic effect on HDF human dermal fibroblast cell was not significant. MB-PDT and rutoside combination induced apoptosis and cell cycle arrest in the human melanoma cancer cell line. Intracellular ROS increased in A375 cancer cell line after the treatment with MB-PDT and rutoside.

Conclusion

The results suggest that, MB-PDT and rutoside could be considered as novel approaches as the combination treatment of melanoma cancer.

The photodynamic and direct actions of methylene blue on mitochondrial energy metabolism: A balance of the useful and harmful effects of this photosensitizer

According to the literature, methylene blue (MB) is a photosensitizer (PS) with a high affinity for mitochondria. Therefore, several studies have explored this feature to evaluate its photodynamic effects on the mitochondrial apoptotic pathway under normoxic conditions. We are aware only of limited reports regarding MB's photodynamic effects on mitochondrial energy metabolism, especially under hypoxic conditions. Thus, the purposes of this study were to determine the direct and photodynamic acute effects of MB on the energy metabolism of rat liver mitochondria under hypoxic conditions and its direct acute effects on several parameters linked to energy metabolism in the isolated perfused rat liver. MB presented a high affinity for mitochondria, irrespective of photostimulation or proton gradient formation. Upon photostimulation, MB demonstrated high in vitro oxidizing species generation ability. Consequently, MB damaged the mitochondrial macromolecules, as could be evidenced by the elevated levels of lipid peroxidation and protein carbonyls. In addition to generating a pro-oxidant environment, MB also led to a deficient antioxidant defence system, as indicated by the reduced glutathione (GSH) depletion. Bioenergetically, MB caused uncoupling of oxidative phosphorylation and led to photodynamic inactivation of complex I, complex II, and F₁F_O-ATP synthase complex, thus decreasing mitochondrial ATP generation. Contrary to what is expected for an ideal PS, MB displayed appreciable dark toxicity on mitochondrial energy metabolism. The results indicated that MB acted via at least three mechanisms: direct damage to the inner mitochondrial membrane; uncoupling of oxidative phosphorylation; and inhibition of electron transfer. Confirming the impairment of mitochondrial energy metabolism, MB also strongly inhibited mitochondrial ATP production. In the perfused rat liver, MB stimulated oxygen consumption, decreased the ATP/ADP ratio, inhibited gluconeogenesis and ureogenesis, and stimulated glycogenolysis, glycolysis, and ammoniagenesis, fully corroborating its uncoupling action in intact cells, as well. It can be concluded that even under hypoxic conditions, MB is a PS with potential for photodynamic effect-induced mitochondrial dysfunction. However, MB disrupts the mitochondrial energy metabolism even in the dark, causing energy-linked liver metabolic changes that could be harmful in specific circumstances.

Overcoming the diverse mechanisms of multidrug resistance in lung cancer cells by photodynamic therapy using pTHPP-loaded PLGA-lipid hybrid nanoparticles

Multidrug resistance (MDR) and the spread of cancer cells (metastasis) are major causes leading to failure of cancer treatment. MDR can develop in two main ways, with differences in their mechanisms for drug resistance, first drug-selected MDR developing after chemotherapeutic treatment, and metastasis-associated MDR acquired by cellular adaptation to microenvironmental changes during metastasis. This study aims to use a nanoparticle-mediated photodynamic therapy (NPs/PDT) approach to overcome both types of MDR. A photosensitizer, 5,10,15,20-Tetrakis(4-hydroxy-phenyl)-21H,23H-porphine (pTHPP) was loaded into poly(D,L-lactide-co-glycolide) (PLGA)-lipid hybrid nanoparticles. The photocytotoxic effect of the nanoparticles was evaluated using two different MDR models established from one cell line, A549 human lung adenocarcinoma, including (1) A549RT-eto, a MDR cell line derived from A549 cells by drug-selection, and (2) detachment-induced MDR acquired by A549 cells when cultured as floating cells under non-adherent conditions, which mimic metastasizing cancer cells in the blood/lymphatic circulation. In the drug-selected MDR model, A549RT-eto cells displayed 17.4- and 1.8-fold resistance to Etoposide and Paclitaxel, respectively, compared to the A549 parental cells. In contrast to treatment with anticancer drugs, NPs/PDT with pTHPP-loaded nanoparticles resulted in equal photocytotoxic effect in A549RT-eto and parental cells. Intracellular pTHPP accumulation and light-induced superoxide anion generation were observed at similar levels in the two cell lines. The NPs/PDT killed A549RT-eto and parental cells through apoptosis as revealed by flow cytometry. In the metastasis-associated MDR model, A549 floating cells exhibited resistance to Etoposide (11.6-fold) and Paclitaxel (57.8-fold) compared to A549 attached cells, but the floating cells failed to show resistance against the photocytotoxic effect of the NPs/PDT. The MDR overcoming activity of NPs/PDT is mainly due to delivery ability of the PLGA-lipid hybrid nanoparticles. In conclusion, this work suggests that PLGA-lipid hybrid nanoparticles have potential in delivering photosensitizer or chemotherapeutic drug for treating both drug-selected and metastasis-associated MDR lung cancer cells.

Anticancer Photodynamic Therapy Properties of Sulfur-Doped Graphene Quantum Dot and Methylene Blue Preparations in MCF-7 Breast Cancer Cell Culture

Photodynamic therapy (PDT) is a field with many applications including chemotherapy. Graphene quantum dots (GQDs) exhibit a variety of unique properties and can be used in PDT to generate singlet oxygen that destroys pathogenic bacteria and cancer cells. The PDT agent, methylene blue (MB), like GQDs, has been successfully exploited to destroy bacteria and cancer cells by increasing reactive oxygen species generation. Recently, combinations of GQDs and MB have been shown to destroy pathogenic bacteria via increased singlet oxygen generation. Here, we performed a spectrophotometric assay to detect and measure the uptake of GQDs, MB and several GQD-MB combinations in MCF-7 breast cancer cells. Then, we used a cell counting method to evaluate the cytotoxicity of GQDs, MB and a 1:1 GQD:MB preparation. Singlet oxygen generation in cells was then detected and measured using singlet oxygen sensor green. The dye, H₂ DCFDA, was used to measure reactive oxygen species production. We found that GQD and MB uptake into MCF-7 cells occurred, but that MB, followed by 1:1 GQD:MB, caused superior cytotoxicity and singlet oxygen and reactive oxygen species generation. Our results suggest that methylene blue's effect against MCF-7 cells is not potentiated by GQDs, either in light or dark conditions.

Imaging Dynamic Peroxynitrite Fluxes in Epileptic Brains with a Near-Infrared Fluorescent Probe

Epilepsy is a chronic neurodegenerative disease, and accumulating evidence suggests its pathological progression is closely associated with peroxynitrite (ONOO-). However, understanding the function remains challenging due to a lack of in vivo imaging probes for ONOO- determination in epileptic brains. Here, the first near-infrared imaging probe (named ONP) is presented for tracking endogenous ONOO- in brains of kainate-induced epileptic seizures with high sensitivity and selectivity. Using this probe, the dynamic changes of endogenous ONOO- fluxes in epileptic brains are effectively monitored with excellent temporal and spatial resolution. In vivo visualization and in situ imaging of hippocampal regions clearly reveal that a higher concentration of ONOO- in the epileptic brains associates with severe neuronal damage and epileptogenesis; curcumin administration can eliminate excessively increased ONOO-, further effectively protecting neuronal cells. Moreover, by combining high-content analysis and ONP, a high-throughput screening method for antiepileptic inhibitors is constructed, which provides a rapid imaging/screening approach for understanding epilepsy pathology and accelerating antiseizure therapeutic discovery.

Transmission electron microscopy revealing the mechanism of action of photodynamic therapy on Trichomonas vaginalis

Trichomonas vaginalis is an amitochondrial parasite that causes human trichomoniasis. Despite metronidazole effectiveness, resistant cases are becoming more frequent. This scenario reveals the need to develop new therapeutic options. Photodynamic Therapy (PDT) is an experimental treatment that involves the activation of photosensitive substances and the generation of cytotoxic oxygen species and free radicals to promote the selective destruction of target tissues. In previous work, we identified an excellent in vitro PDT activity using methylene blue and light emitting diode against metronidazole sensitive and resistant strains of T. vaginalis. Here, we evaluated the efficacy of PDT in vivo and its high trichomonicidal activity was assessed through transmission electron microscopy. Female Balb/c mice were infected intravaginally with T. vaginalis trophozoites. On the third day of infection, methylene blue was introduced into the vaginal canal, which then received 68.1 J/cm² of radiation for 35.6 s. Twenty-four hours after treatment the vaginal canal of the animals was scraped and the samples processed by the immunocytochemistry technique. Besides that, in vitro photodynamic treatment was performed and T. vaginalis trophozoites were processed by transmission electron microscopy. PDT significantly reduced infection in animals treated, compared to control groups, being as efficient as metronidazole. Morphological changes observed have suggested that PDT activity on T. vaginalis was due to necrosis. These results, added to the high trichomonicidal activity of PDT confirm its feasibility for trichomoniasis treatment.

Parallel damage in mitochondria and lysosomes is an efficient way to photoinduce cell death

Cells challenged by photosensitized oxidations face strong redox stresses and rely on autophagy to either survive or die. However, the use of macroautophagy/autophagy to improve the efficiency of photosensitizers, in terms of inducing cell death, remains unexplored. Here, we addressed the concept that a parallel damage in the membranes of mitochondria and lysosomes leads to a scenario of autophagy malfunction that can greatly improve the efficiency of the photosensitizer to cause cell death. Specific damage to these organelles was induced by irradiation of cells pretreated with 2 phenothiazinium salts, methylene blue (MB) and 1,9-dimethyl methylene blue (DMMB). At a low concentration level (10 nM), only DMMB could induce mitochondrial damage, leading to mitophagy activation, which did not progress to completion because of the parallel damage in lysosome, triggering cell death. MB-induced photodamage was perceived almost instantaneously after irradiation, in response to a massive and nonspecific oxidative stress at a higher concentration range (2 µM). We showed that the parallel damage in mitochondria and lysosomes activates and inhibits mitophagy, leading to a late and more efficient cell death, offering significant advantage (2 orders of magnitude) over photosensitizers that cause unspecific oxidative stress. We are confident that this concept can be used to develop better light-activated drugs. Abbreviations: ΔΨm: mitochondrial transmembrane inner potential; AAU: autophagy arbitrary units; ATG5, autophagy related 5; ATG7: autophagy related 7; BAF: bafilomycin A1; BSA: bovine serum albumin; CASP3: caspase 3; CF: carboxyfluorescein; CTSB: cathepsin B; CVS: crystal violet staining; DCF: dichlorofluorescein; DCFH2: 2',7'-dichlorodihydrofluorescein; DMMB: 1,9-dimethyl methylene blue; ER: endoplasmic reticulum; HaCaT: non-malignant immortal keratinocyte cell line from adult human skin; HP: hydrogen peroxide; LC3B-II: microtubule associated protein 1 light chain 3 beta-II; LMP: lysosomal membrane permeabilization; LTG: LysoTracker™ Green DND-26; LTR: LysoTracker™ Red DND-99; 3-MA: 3-methyladenine; MB: methylene blue; mtDNA: mitochondrial DNA; MitoSOX™: red mitochondrial superoxide probe; MTDR: MitoTracker™ Deep Red FM; MTO: MitoTracker™ Orange CMTMRos; MT-ND1: mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1; MTT: methylthiazolyldiphenyl-tetrazolium bromide; 1O2: singlet oxygen; OH. hydroxil radical; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase; PBS: phosphate-buffered saline; PI: propidium iodide; PDT: photodynamic therapy; PS: photosensitizer; QPCR: gene-specific quantitative PCR-based; Rh123: rhodamine 123; ROS: reactive oxygen species RTN: rotenone; SQSTM1/p62: sequestosome 1; SUVs: small unilamellar vesicles; TBS: Tris-buffered saline.

Photo-Crosslinked Polymeric Matrix with Antimicrobial Functions for Excisional Wound Healing in Mice

Wound infection extends the duration of wound healing and also causes systemic infections such as sepsis, and, in severe cases, may lead to death. Early prevention of wound infection and its appropriate treatment are important. A photoreactive modified gelatin (GE-BTHE) was synthesized by gelatin and a conjugate formed from the 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and the 2-hydroxyethyl methacrylate (HEMA). Herein, we investigated the photocurable polymer solution (GE-BTHE mixture) containing GE-BTHE, poly(ethylene glycol) diacrylate (PEGDA), chitosan, and methylene blue (MB), with antimicrobial functions and photodynamic antimicrobial chemotherapy for wound dressing. This photocurable polymer solution was found to have fast film-forming property attributed to the photochemical reaction between GE-BTHE and PEGDA, as well as the antibacterial activity in vitro attributed to the ingredients of chitosan and MB. Our in vivo results also demonstrated that untreated wounds after 3 days had the same scab level as the GE-BTHE mixture-treated wounds after 20 s of irradiation, which indicates that the irradiated GE-BTHE mixture can be quickly transferred into artificial scabs to protect wounds from an infection that can serve as a convenient excisional wound dressing with antibacterial efficacy. Therefore, it has the potential to treat nonhealing wounds, deep burns, diabetic ulcers and a variety of mucosal wounds.

Superstructure-Dependent Loading of DNA Origami Nanostructures with a Groove-Binding Drug

DNA origami nanostructures are regarded as powerful and versatile vehicles for targeted drug delivery. So far, DNA origami-based drug delivery strategies mostly use intercalation of the therapeutic molecules between the base pairs of the DNA origami's double helices for drug loading. The binding of nonintercalating drugs to DNA origami nanostructures, however, is less studied. Therefore, in this work, we investigate the interaction of the drug methylene blue (MB) with different DNA origami nanostructures under conditions that result in minor groove binding. We observe a noticeable effect of DNA origami superstructure on the binding affinity of MB. In particular, non-B topologies as for instance found in designs using the square lattice with 10.67 bp/turn may result in reduced binding affinity because groove binding efficiency depends on groove dimensions. Also, mechanically flexible DNA origami shapes that are prone to structural fluctuations may exhibit reduced groove binding, even though they are based on the honeycomb lattice with 10.5 bp/turn. This can be attributed to the induction of transient over- and underwound DNA topologies by thermal fluctuations. These issues should thus be considered when designing DNA origami nanostructures for drug delivery applications that employ groove-binding drugs.

Molecular Dynamics Modeling of Methylene Blue-DOPC Lipid Bilayer Interactions

We present a coarse-grained MARTINI model for methylene blue (MB) and investigate the interactions of MB with dioleylphosphatidylcholine (DOPC) lipid bilayers by molecular dynamics simulations. Our results show that the charge state of MB and the oxidation degree of the DOPC bilayer play critical roles on membrane properties. Oxidation of the DOPC bilayer significantly increases permeability of water and MB molecules, irrespective of the charge state of MB. The most significant changes in membrane properties are obtained for peroxidized lipid bilayers in the presence of cationic MB, with ∼11% increase in the membrane area per lipid head group and ∼7 and 44% reduction in membrane thickness and lateral diffusivity, respectively.

Photodynamic Effect of Methylene Blue and Low Level Laser Radiation in Head and Neck Squamous Cell Carcinoma Cell Lines

Photodynamic therapy (PDT) is suggested to have an impact on the treatment of early stage head and neck cancers (HNSCC). We investigated the effect of PDT with methylene blue (MB) and a diode laser (660 nm) as the laser source on HNSCC cell lines as an in vitro model of surface oral squamous cell carcinoma. Cell-cultures were exposed to 160 µM MB for 4 min and to laser light for 8 min. Viability was proven via cell viability assay and clonogenic survival via clone counting assay. The combination of MB and diode laser evidenced high efficient loss of cell viability by 5% of the control, while treatment with the same concentration of MB for 4 min alone showed a viability of 46% of the control. In both SCC-25 and Detroit 562 HNSCC cells, MB combined with the laser allowed a significant abrogation of clonogenic growth (p < 0.01), especially in the case of Detroit 562 cells less than 1% of the suspension plated cells were able to grow tumor cell nests. Multiresistant (Detroit 562) HNSCC cells expressing cancer stem cell markers are sensitive to MB/red laser combined PDT.

3D lung spheroid cultures for evaluation of photodynamic therapy (PDT) procedures in microfluidic Lab-on-a-Chip system

The purpose of this paper is to present a fully integrated microchip for the evaluation of PDT procedures efficiency on 3D lung spheroid cultures. Human lung carcinoma A549 and non-malignant MRC-5 spheroids were utilized as culture models. Spheroid viability was evaluated 24 h after PDT treatment, in which 5-aminolevulinic acid (ALA) had been used as a precursor of a photosensitizer (protoporphyrin IX - PpIX). Moreover, spheroid viability over a long-term (10-day) culture was also examined. We showed that the proposed PDT treatment was toxic only for cancer spheroids. This could be because of a much-favoured enzymatic conversion of ALA to PpIX in cancer as opposed normal cells. Moreover, we showed that to obtain high effectiveness of ALA-PDT on lung cancer spheroids additional time of spheroid after light exposure was required. It was found that PDT had been effective 5 days after PDT treatment with 3 mM ALA. To the best of our knowledge this has been the first presentation of such research performed on a 3D lung spheroids culture in a microfluidic system.

Enhancing Photodynamic Therapy through Resonance Energy Transfer Constructed Near-Infrared Photosensitized Nanoparticles

Photodynamic therapy (PDT) is an important cancer treatment modality due to its minimally invasive nature. However, the efficiency of existing PDT drug molecules in the deep-tissue-penetrable near-infrared (NIR) region has been the major hurdle that has hindered further development and clinical usage of PDT. Thus, herein a strategy is presented to utilize a resonance energy transfer (RET) mechanism to construct a novel dyad photosensitizer which is able to dramatically boost NIR photon utility and enhance singlet oxygen generation. In this work, the energy donor moiety (distyryl-BODIPY) is connected to a photosensitizer (i.e., diiodo-distyryl-BODIPY) to form a dyad molecule (RET-BDP). The resulting RET-BDP shows significantly enhanced absorption and singlet oxygen efficiency relative to that of the acceptor moiety of the photosensitizer alone in the NIR range. After being encapsulated with biodegradable copolymer pluronic F-127-folic acid (F-127-FA), RET-BDP molecules can form uniform and small organic nanoparticles that are water soluble and tumor targetable. Used in conjunction with an exceptionally low-power NIR LED light irradiation (10 mW cm-2 ), these nanoparticles show superior tumor-targeted therapeutic PDT effects against cancer cells both in vitro and in vivo relative to unmodified photosensitizers. This study offers a new method to expand the options for designing NIR-absorbing photosensitizers for future clinical cancer treatments.

Methylene blue photodynamic therapy induces selective and massive cell death in human breast cancer cells

BACKGROUND

Breast cancer is the main cause of mortality among women. The disease presents high recurrence mainly due to incomplete efficacy of primary treatment in killing all cancer cells. Photodynamic therapy (PDT), an approach that causes tissue destruction by visible light in the presence of a photosensitizer (Ps) and oxygen, appears as a promising alternative therapy that could be used adjunct to chemotherapy and surgery for curing cancer. However, the efficacy of PDT to treat breast tumours as well as the molecular mechanisms that lead to cell death remain unclear.

METHODS

In this study, we assessed the cell-killing potential of PDT using methylene blue (MB-PDT) in three breast epithelial cell lines that represent non-malignant conditions and different molecular subtypes of breast tumours. Cells were incubated in the absence or presence of MB and irradiated or not at 640 nm with 4.5 J/cm2. We used a combination of imaging and biochemistry approaches to assess the involvement of classical autophagic and apoptotic pathways in mediating the cell-deletion induced by MB-PDT. The role of these pathways was investigated using specific inhibitors, activators and gene silencing.

RESULTS

We observed that MB-PDT differentially induces massive cell death of tumour cells. Non-malignant cells were significantly more resistant to the therapy compared to malignant cells. Morphological and biochemical analysis of dying cells pointed to alternative mechanisms rather than classical apoptosis. MB-PDT-induced autophagy modulated cell viability depending on the cell model used. However, impairment of one of these pathways did not prevent the fatal destination of MB-PDT treated cells. Additionally, when using a physiological 3D culture model that recapitulates relevant features of normal and tumorous breast tissue morphology, we found that MB-PDT differential action in killing tumour cells was even higher than what was detected in 2D cultures.

CONCLUSIONS

Finally, our observations underscore the potential of MB-PDT as a highly efficient strategy which could use as a powerful adjunct therapy to surgery of breast tumours, and possibly other types of tumours, to safely increase the eradication rate of microscopic residual disease and thus minimizing the chance of both local and metastatic recurrence.

Complexing Methylene Blue with Phosphorus Dendrimers to Increase Photodynamic Activity

The efficiency of photodynamic therapy is limited mainly due to low selectivity, unfavorable biodistribution of photosensitizers, and long-lasting skin sensitivity to light. However, drug delivery systems based on nanoparticles may overcome the limitations mentioned above. Among others, dendrimers are particularly attractive as carriers, because of their globular architecture and high loading capacity. The goal of the study was to check whether an anionic phosphorus dendrimer is suitable as a carrier of a photosensitizer-methylene blue (MB). As a biological model, basal cell carcinoma cell lines were used. We checked the influence of the MB complexation on its singlet oxygen production ability using a commercial fluorescence probe. Next, cellular uptake, phototoxicity, reactive oxygen species (ROS) generation, and cell death were investigated. The MB-anionic dendrimer complex (MB-1an) was found to generate less singlet oxygen; however, the complex showed higher cellular uptake and phototoxicity against basal cell carcinoma cell lines, which was accompanied with enhanced ROS production. Owing to the obtained results, we conclude that the photodynamic activity of MB complexed with an anionic dendrimer is higher than free MB against basal cell carcinoma cell lines.

Polypyrrole–methylene blue nanoparticles as a single multifunctional nanoplatform for near-infrared photo-induced therapy and photoacoustic imaging

A novel contrast agent with broad NIR absorbing properties for combined photo-induced therapy and photoacoustic imaging.

DNA photo-cleaving agents in the far-red to near-infrared range – a review

Ideal photonucleases for clinical applications cleave DNA upon activation with deeply penetrating far-red to near-infrared light.

Photodynamic Efficiency: From Molecular Photochemistry to Cell Death

Photodynamic therapy (PDT) is a clinical modality used to treat cancer and infectious diseases. The main agent is the photosensitizer (PS), which is excited by light and converted to a triplet excited state. This latter species leads to the formation of singlet oxygen and radicals that oxidize biomolecules. The main motivation for this review is to suggest alternatives for achieving high-efficiency PDT protocols, by taking advantage of knowledge on the chemical and biological processes taking place during and after photosensitization. We defend that in order to obtain specific mechanisms of cell death and maximize PDT efficiency, PSes should oxidize specific molecular targets. We consider the role of subcellular localization, how PS photochemistry and photophysics can change according to its nanoenvironment, and how can all these trigger specific cell death mechanisms. We propose that in order to develop PSes that will cause a breakthrough enhancement in the efficiency of PDT, researchers should first consider tissue and intracellular localization, instead of trying to maximize singlet oxygen quantum yields in in vitro tests. In addition to this, we also indicate many open questions and challenges remaining in this field, hoping to encourage future research.

Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals

Antimicrobial photodynamic therapy (APDT) combined with endodontic treatment has been recognized as an alternative approach to complement conventional root canal disinfection methods on bacterial biofilms. We developed an in  vitro model of bioluminescent Candida albicans biofilm inside curved dental root canals and investigated the microbial reduction produced when different light delivery methods are employed. Each light delivery method was evaluated in respect to the light distribution provided inside curved root canals. After conventional endodontic preparation, teeth were sterilized before canals were contaminated by a bioluminescent strain of C. albicans (CEC789). Methylene blue (90 μM) was introduced into the canals and then irradiated (λ = 660 nm, P = 100 mW, beam diameter = 2 mm) with laser tip either in contact with pulp chamber or within the canal using an optical diffuser fiber. Light distribution was evaluated by CCD camera, and microbial reduction was monitored through bioluminescence imaging. Our findings demonstrated that the bioluminescent C. albicans biofilm model had good reproducibility and uniformity. Light distribution in dental tissue was markedly dependent on the light delivery system, and this strategy was directly related to microbial destruction. Both light delivery systems performed significant fungal inactivation. However, when irradiation was performed with optical diffuser fiber, microbial burden reduction was nearly 100 times more effective. Bioluminescence is an interesting real-time analysis to endodontic C. albicans biofilm inactivation. APDT showed to be an effective way to inactivate C. albicans biofilms. Diffuser fibers provided optimized light distribution inside curved root canals and significantly increased APDT efficiency.

Preparation and evaluation of hypocrellin A loaded poly(lactic-co-glycolic acid) nanoparticles for photodynamic therapy

The PLGA/HA NPs showed improved dispersibility and enhanced photostability, while maintaining high phototoxicity and ROS production ability.