A review of progress in clinical photodynamic therapy

Comparison of high and low molecular weight chitosan as in-vitro boosting agent for photodynamic therapy against Helicobacter pylori using methylene blue and endoscopic light

BACKGROUND

We reported in a previous study that photodynamic therapy (PDT) of Helicobacter pylori(H. pylori) could potentiate bactericidal effect by adding chitosan. As a next step, we compared the bactericidal effects of low molecular weight (LMW) combined with Photodynamic Therapy to high molecular weight (HMW) chitosan.

METHOD

To perform PDT to kill H. pylori, we used endoscopic light as light source, methylene blue (MB) as a photosensitizer and chitosan (310-375, 50-190 kDa). We evaluated bacterial removal rate and its membrane damage by ethidium bromide monoazide PCR method (EMA q-PCR). 8-oxo-2'-dexoyguanosine by ELISA was measured for oxidative stress.

RESULTS

At a chitosan concentration of ≤0.05%, the killing effect did not differ between the two molecular weights, and 100% bacterial removal rate was observed at a light energy ≥ 6.23 mJ/cm² powers under 0.02% MB. After 15 min irradiation, LMW chitosan with high concentration of MB (0.004%) showed highest killing effects, which were consistent with the results of EMA q-PCR but not with the level of 8-OHdG. Bactericidal effects of LMW chitosan plus PDT using 0.002 and 0.004% MB for 15 min irradiation were significantly higher than those using HMW chitosan plus PDT.

CONCLUSION

We found that PDT using methylene blue with LMW chitosan to kill H. pylori exerted greater bactericidal effects through bacterial membrane damage than PDT with HMW chitosan. These results suggest that it would be better to choose LMW chitosan to enhance the effect of PDT for clinical application, even at a very low concentration of PS.

Nanoparticles to mediate X-ray-induced photodynamic therapy and Cherenkov radiation photodynamic therapy

Photodynamic therapy (PDT) has emerged as an attractive option for cancer treatment. However, conventional PDT is activated by light that has poor tissue penetration depths, limiting its applicability in the clinic. Recently the idea of using X-ray sources to activate PDT and overcome the shallow penetration issue has garnered significant interest. This can be achieved by external beam irradiation and using a nanoparticle scintillator as transducer. Alternatively, research on exploiting Cherenkov radiation from radioisotopes to activate PDT has also begun to flourish. In either approach, the most auspicious success is achieved using nanoparticles as either a scintillator or a photosensitizer to mediate energy transfer and radical production. Both X-ray induced PDT (X-PDT) and Cherenkov radiation PDT (CR-PDT) contain a significant radiation therapy (RT) component and are essentially PDT and RT combination. Unlike the conventional combination, however, in X-PDT and CR-PDT, one energy source simultaneously activates both processes, making the combination always in synchronism and the synergy potential maximized. While still in early stage of development, X-PDT and CR-PDT address important issues in the clinic and hold great potential in translation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Validation of combined Monte Carlo and photokinetic simulations for the outcome correlation analysis of benzoporphyrin derivative-mediated photodynamic therapy on mice

We compare previously reported benzoporphyrin derivative (BPD)-mediated photodynamic therapy (PDT) results for reactive singlet oxygen concentration (also called singlet oxygen dose) on mice with simulations using a computational device, Dosie™, that calculates light transport and photokinetics for PDT in near real-time. The two sets of results are consistent and validate the use of the device in PDT treatment planning to predict BPD-mediated PDT outcomes in mice animal studies based on singlet oxygen dose, which showed a much better correlation with the cure index than the conventional light dose.

Applications of SNAP-tag technology in skin cancer therapy

BACKGROUND

Cancer treatment in the 21st century has seen immense advances in optical imaging and immunotherapy. Significant progress has been made in the bioengineering and production of immunoconjugates to achieve the goal of specifically targeting tumors.

DISCUSSION

In the 21st century, antibody drug conjugates (ADCs) have been the focus of immunotherapeutic strategies in cancer. ADCs combine the unique targeting of monoclonal antibodies (mAbs) with the cancer killing ability of cytotoxic drugs. However, due to random conjugation methods of drug to antibody, ADCs are associated with poor antigen specificity and low cytotoxicity, resulting in a drug to antibody ratio (DAR) >1. This means that the cytotoxic drugs in ADCs are conjugated randomly to antibodies, by cysteine or lysine residues. This generates heterogeneous ADC populations with 0 to 8 drugs per an antibody, each with distinct pharmacokinetic, efficacy, and toxicity properties. Additionally, heterogeneity is created not only by different antibody to ligand ratios but also by different sites of conjugation. Hence, much effort has been made to find and establish antibody conjugation strategies that enable us to better control stoichiometry and site-specificity. This includes utilizing protein self-labeling tags as fusion partners to the original protein. Site-specific conjugation is a significant characteristic of these engineered proteins. SNAP-tag is one such engineered self-labeling protein tag shown to have promising potential in cancer treatment. The SNAP-tag is fused to an antibody of choice and covalently reacts specifically in a 1:1 ratio with benzylguanine (BG) substrates, eg, fluorophores or photosensitizers, to target skin cancer. This makes SNAP-tag a versatile technique in optical imaging and photoimmunotherapy of skin cancer.

CONCLUSION

SNAP-tag technology has the potential to contribute greatly to a broad range of molecular oncological applications because it combines efficacious tumor targeting, minimized local and systemic toxicity, and noninvasive assessment of diagnostic/prognostic molecular biomarkers of cancer.

Hypoxia-Triggered Transforming Immunomodulator for Cancer Immunotherapy via Photodynamically Enhanced Antigen Presentation of Dendritic Cell

A key factor for successful cancer immunotherapy (CIT) is the extent of antigen presentation by dendritic cells (DCs) that phagocytize tumor-associated antigens (TAA) in the tumor site and migrate to tumor draining lymph nodes (TDLN) for the activation of T cells. Although various types of adjuvant delivery have been studied to enhance the activity of the DCs, poor delivery efficiency and depleted population of tumor infiltrating DCs have limited the efficacy of CIT. Herein, we report a hypoxia-responsive mesoporous silica nanocarrier (denoted as CAGE) for an enhanced CIT assisted by photodynamic therapy (PDT). In this study, CAGE was designed as a hypoxia-responsive transforming carrier to improve the intracellular uptake of nanocarriers and the delivery of adjuvants to DCs. Furthermore, PDT was exploited for the generation of immunogenic debris and recruitment of DCs in a tumor site, followed by enhanced antigen presentation. Finally, a significant inhibition of tumor growth was observed in vivo, signifying that the PDT would be a promising solution for DC-based immunotherapy.

Elucidating the mode of action for thiophene-based organic D-π-A sensitizers for use in photodynamic therapy

Photodynamic therapy (PDT) is a non-invasive, selective, and cost-effective cancer therapy. The development of readily accessible templates that allow rapid structural modification for further improvement of PDT remains important. We previously reported thiophene-based organic D-π-A sensitizers consisted of an electron-donating (D) moiety, a π-conjugated bridge (π) moiety, and an electron-accepting (A) moiety as valuable templates for a photosensitizer that can be used in PDT. Our preliminary structure-activity relationship study revealed that the structure of the A moiety significantly influences its phototoxicity. In this study, we evaluated the photoabsorptive, cellular uptake, and photo-oxidizing abilities of D-π-A sensitizers that contained different A moieties. The level of phototoxicity of the D-π-A sensitizers was rationalized by considering those three abilities. In addition, we observed the ability of amphiphilic sensitizers containing either a carboxylic acid or an amide in an A moiety to form aggregates that penetrate cells mainly via endocytosis.

Encapsulation of tDodSNO generates a photoactivated nitric oxide releasing nanoparticle for localized control of vasodilation and vascular hyperpermeability

We report the synthesis and characterization of a photoactive nitric oxide (NO) releasing nanoparticle (NP) by encapsulation of the NO donor tert-dodecane S-nitrosothiol (tDodSNO) into a co-polymer of styrene and maleic anhydride (SMA) to afford SMA-tDodSNO. Encapsulation did not affect tDodSNO's stability or NO release profile, but imparted water solubility and protection from degradation reactions with glutathione. Under photoactivation the NP acted as a potent NO donor, with photoactivation acting as a switch to induce localized vasodilation in aortic rings (EC₅₀^* 660 nM at 2700 W/m²) and cause vascular hyperpermeability in mesenteric beds (8-fold increase in dye uptake at 1 µM SMA-tDodSNO with 460 W/m² photoactivation). The NP was markedly superior as a photoactive NO donor in comparison to the S-nitrosothiols GSNO and SNAP, which are commonly used in experimental studies, as well as sodium nitroprusside, a clinically used vasodilator. Future development of this NP may find wide ranging therapeutic applications for treating cardiovascular disease and other disorders related to NO signaling, as well as enhancing macromolecular drug delivery to target organs through selective hyperpermeability. Supporting information describing the biophysical characterization of SMA-tDodSNO is supplied in an accompanying Data in Brief article (Alimoradi et al., doi: 10.1016/j.dib.2018.10.149).

Imaging and therapeutic applications of persistent luminescence nanomaterials

The development of probes for biomolecular imaging and diagnostics is a very active research area. Among the different imaging modalities, optics emerged since it is a noninvasive and cheap imaging technique allowing real time imaging. In vitro, this technique is very useful however in vivo, fluorescence suffers from low signal-to-noise ratio due to tissue autofluorescence under constant excitation. To address this limitation, novel types of optical nanoprobes are actually being developed and among them, persistent luminescence nanoparticles (PLNPs), with long lasting near-infrared (NIR) luminescence capability, allows doing optical imaging without constant excitation and so without autofluorescence. This review will begin by introducing the physical phenomenon associated to the long luminescence decay of such nanoprobes, from minutes to hours after ceasing the excitation. Then we will show how this property can be used to develop in vivo imaging probes and also more recently nanotheranostic agents. Finally, preliminary data on their biocompatibility will be mentioned and we will conclude by envisioning on the future applications and improvements of such nanomaterials.

Two-photon absorption properties of BODIPY-like compounds based on BF2–naphthyridine complexes

High two-photon absorption cross-sections of BODIPY-like compounds were obtained for simple structures.

External stimulus responsive inorganic nanomaterials for cancer theranostics

Cancer is a highly intelligent system of cells, that works together with the body to thrive and subsequently overwhelm the host in order for its survival. Therefore, treatment regimens should be equally competent to outsmart these cells. Unfortunately, it is not the case with current therapeutic practices, the reason why it is still one of the most deadly adversaries and an imposing challenge to healthcare practitioners and researchers alike. With rapid nanotechnological interventions in the medical arena, the amalgamation of diagnostic and therapeutic functionalities into a single platform, theranostics provides a never before experienced hope of enhancing diagnostic accuracy and therapeutic efficiency. Additionally, the ability of these nanotheranostic agents to perform their actions on-demand, i.e. can be controlled by external stimulus such as light, magnetic field, sound waves and radiation has cemented their position as next generation anti-cancer candidates. Numerous reports exist of such stimuli-responsive theranostic nanomaterials against cancer, but few have broken through to clinical trials, let alone clinical practice. This review sheds light on the pros and cons of a few such theranostic nanomaterials, especially inorganic nanomaterials which do not require any additional chemical moieties to initiate the stimulus. The review will primarily focus on preclinical and clinical trial approved theranostic agents alone, describing their success or failure in the respective stages.

A H₂O₂-Responsive Boron Dipyrromethene-Based Photosensitizer for Imaging-Guided Photodynamic Therapy

In this study, we demonstrate a novel H₂O₂ activatable photosensitizer (compound 7) which contains a diiodo distyryl boron dipyrromethene (BODIPY) core and an arylboronate group that quenches the excited state of the BODIPY dye by photoinduced electron transfer (PET). The BODIPY-based photosensitizer is highly soluble and remains nonaggregated in dimethyl sulfoxide (DMSO) as shown by the intense and sharp Q-band absorption (707 nm). As expected, compound 7 exhibits negligible fluorescence emission and singlet oxygen generation efficiency. However, upon interaction with H₂O₂, both the fluorescence emission and singlet oxygen production of the photosensitizer can be restored in phosphate buffered saline (PBS) solution and PBS buffer solution containing 20% DMSO as a result of the cleavage of the arylboronate group. Due to the higher concentration of H₂O₂ in cancer cells, compound 7 even with low concentration is particularly sensitive to human cervical carcinoma (HeLa) cells (IC50 = 0.95 μM) but hardly damage human embryonic lung fibroblast (HELF) cells. The results above suggest that this novel BODIPY derivative is a promising candidate for fluorescence imaging-guided photodynamic cancer therapy.

Effects of nanoparticles of hydroxy-aluminum phthalocyanine on markers of liver injury and glucose metabolism in diabetic mice

Photodynamic therapy, by reducing pain and inflammation and promoting the proliferation of healthy cells, can be used to treat recurrent lesions, such as diabetic foot ulcers. Studies using the photosensitizer phthalocyanine, together with the nanostructured copolymeric matrix of Pluronic® and Carbopol® for the treatment of diabetic foot ulcers and leishmaniosis lesions, are showing promising outcomes. Despite their topical or subcutaneous administration, these molecules are absorbed and their systemic effects are unknown. Therefore, we investigated the effect of the subcutaneous administration of the hydroxy-aluminum phthalocyanine hydrogel without illumination on systemic parameters, markers of liver injury, and liver energy metabolism in type 1 diabetic Swiss mice. Both the hydrogel and the different doses of phthalocyanine changed the levels of injury markers and the liver glucose release, sometimes aggravating the alterations caused by the diabetic condition itself. However, the dose of 2.23 µg/mL caused less marked plasmatic and metabolic changes and did not change glucose tolerance or insulin sensitivity of the diabetic mice. These results are indicative that the use of hydroxy-aluminum phthalocyanine hydrogel for the treatment of cutaneous ulcers in diabetic patients is systemically safe.

Transferrin/aptamer conjugated mesoporous ruthenium nanosystem for redox-controlled and targeted chemo-photodynamic therapy of glioma

The blood-brain barrier (BBB) and low targeting are major obstacles for the treatment of gliomas. Accordingly, overcoming the BBB and enhancing the targeting of drugs to the glioma area are key to achieving a good therapeutic effect. Here, we have developed the mesoporous ruthenium nanosystem RBT@MRN-SS-Tf/Apt with dual targeting function. Transferrin (Tf) and aptamer AS1411 (Apt) are grafted on the surfaces of mesoporous ruthenium nanoparticles (MRN) with high loading capacity. This is achieved via redox-cleavable disulfide bonds, serving as both a capping agent and a targeting ligand, enabling the effective penetration of the blood-brain barrier and targeting the glioma. In addition, RBT@MRN-SS-Tf/Apt can specifically kill glioma cells in vitro and in vivo. Moreover, anti-tumor drugs [Ru(bpy)₂(tip)]²⁺ (RBT) will produce reactive oxygen species and induce apoptosis of tumor cells under laser irradiation, providing photodynamic therapy (PDT) for the treatment of gliomas, and further prolonging the median survival period. The study shows that this chemical photodynamic therapy nanosystem can be used as an efficient and powerful synergistic system for the treatment of brain tumors and other brain diseases of the central nervous system. STATEMENT OF SIGNIFICANCE: In order to overcome the blood-brain barrier and low targeting, and enhance the anti-glioma activities of nanodrugs. We have developed RBT@MRN-SS-Tf/Apt with dual targeting function. It is achieved release drug via redox-cleavable disulfide bonds, and enable the effective penetration of the blood-brain barrier and targeting the glioma. Moreover, anti-tumor drugs RBT will produce reactive oxygen species and induce apoptosis of tumor cells under laser irradiation, providing photodynamic therapy (PDT) for the treatment of gliomas, and further prolonging the median survival period. Therefore, this chemical photodynamic therapy nanosystem can be used as an efficient and powerful synergistic system for the treatment of brain tumors and other brain diseases of the central nervous system.

Assessing Configurational Sampling in the Quantum Mechanics/Molecular Mechanics Calculation of Temoporfin Absorption Spectrum and Triplet Density of States

The absorption properties of Temoporfin, a second-generation photosensitizer employed in photodynamic therapy, are calculated with an electrostatic-embedding quantum mechanics/molecular mechanics (QM/MM) scheme in methanol. The suitability of several ensembles of geometries generated by different sampling techniques, namely classical-molecular-dynamics (MD) and QM/MM-MD thermal sampling, Wigner quantum sampling and a hybrid protocol, which combines the thermal and quantum approaches, is assessed. It is found that a QM description of the chromophore during the sampling is needed in order to achieve a good agreement with respect to the experimental spectrum. Such a good agreement is obtained with both QM/MM-MD and Wigner samplings, demonstrating that a proper description of the anharmonic motions of the chromophore is not relevant in the computation of the absorption properties. In addition, it is also found that solvent organization is a rather fast process and a long sampling is not required. Finally, it is also demonstrated that the same exchange-correlation functional should be employed in the sampling and in the computation of the excited states properties to avoid unphysical triplet states with relative energies close or below 0 eV.

Exogenous imaging contrast and therapeutic agents for intravascular photoacoustic imaging and image-guided therapy

Intravascular photoacoustic (IVPA) imaging has been developed in recent years as a viable imaging modality for the assessment of atherosclerotic plaques. Exogenous imaging contrast and therapeutic agents further enhance this imaging modality and provide significant benefits. Imaging contrast agents can significantly increase photoacoustic signal, resulting in enhanced plaque detection and characterization. The ability to use these particles to molecularly target markers of disease progression makes it possible to determine patient-specific levels of risk and plan treatments accordingly. With improved diagnosis, clinicians will be able to use therapeutic agents that are synergistic with IVPA imaging to treat atherosclerotic patients. Pre-clinical and clinical studies with relevance to IVPA imaging have shown promise in the area of diagnosis and therapeutics. In this review, we present a variety of imaging contrast agents that are either designed for or are compatible with IVPA imaging, cover uses of therapeutic agents that compliment this imaging modality, and discuss future directions of research in the field.

Synthesis of fluorine-containing phthalocyanines and investigation of the photophysical and photochemical properties of the metal-free and zinc phthalocyanines

4-(3-(Trifluoromethyl)benzylthio)phthalonitrile (1) was synthesized. Metal-free phthalocyanine 2, zinc(II) phthalocyanine 3 and cobalt(II) phthalocyanine 4 were synthesized starting with dinitrile compound 1. Photodynamic therapy properties of 2 and 3 were studied.

The design, synthesis, and evaluation of organic dithienopyrrole-based D-π-A dyes for use as sensitizers in photodynamic therapy

Dithienopyrrole-based organic dyes that combine an electron-donating moiety (D), a π-conjugated bridge moiety (π), and an electron-accepting moiety (A) were designed and synthesized in short steps by previously developed one-pot Suzuki-Miyaura coupling approach. Absorption wavelengths of the dyes were readily tuned by altering the D and A moieties. The use of a strongly electron-withdrawing cyanopyridone acceptor enabled NIR absorption. A synthesized sensitizer, 2j, exerted potent phototoxicity mainly via a Type I mechanism in cells. A nitrogen atom in the dithienopyrrole ring serves as a connecting point for the introduction of functional building blocks that can improve the properties of sensitizers, which makes this D-π-A sensitizer a valuable template for the further development of sensitizers.

Light-activatable cannabinoid prodrug for combined and target-specific photodynamic and cannabinoid therapy

Cannabinoids are emerging as promising antitumor drugs. However, complete tumor eradication solely by cannabinoid therapy remains challenging. In this study, we developed a far-red light activatable cannabinoid prodrug, which allows for tumor-specific and combinatory cannabinoid and photodynamic therapy. This prodrug consists of a phthalocyanine photosensitizer (PS), reactive oxygen species (ROS)-sensitive linker, and cannabinoid. It targets the type-2 cannabinoid receptor (CB2R) overexpressed in various types of cancers. Upon the 690-nm light irradiation, the PS produces cytotoxic ROS, which simultaneously cleaves the ROS-sensitive linker and subsequently releases the cannabinoid drug. We found that this unique multifunctional prodrug design offered dramatically improved therapeutic efficacy, and therefore provided a new strategy for targeted, controlled, and effective antitumor cannabinoid therapy.

Highly efficient and biocompatible nanoparticle-based photosensitizer for treatment of acne vulgaris

Aim: Nanoparticle-based photosensitizers containing silver core and mesoporous silica shell with hematoporphyrin IX embedded were developed to treat vulgaris photodynamically. Materials & methods: The hybrid photosensitizers were dispersed in 30% polyethylene glycol (PEG-200) solution and used for the photodynamic treatment of Staphylococcus epidermidis and Propionibacterium acnes under the illumination of a portable LED (∼410 nm). Results: After a 5 min illumination by the LED, the hybrid photosensitizers of 50 μg/ml displayed killing efficacy of approximately 5-log for S. epidermidis and approximately 4-log for P. acnes. Results indicated that hybrid photosensitizers in PEG-200 matrix perform better than in deionized (DI) water (∼1-log increase in killing efficacy).Conclusion: Under short illumination of a portable LED, hybrid photosensitizers demonstrated immense potential for treatment of acne vulgaris without involving antibiotics.

Photodynamic therapy reduces the inhibitory effect of osteosarcoma cells on dendritic cells by upregulating HSP70

Osteosarcoma is the most common primary bone tumor and predominantly affects children and adolescents. The prognosis for patients with osteosarcoma is poor. Therefore, the development of novel treatments for osteosarcoma is required. Photodynamic therapy (PDT) is a disease site-specific treatment that utilizes a photosensitizing agent along with light to kill cancer cells. This agent only works following activation by certain wavelengths of light. After the agent is absorbed by the cancer cells, light is then applied to the area to be treated. The light causes the drug to react with oxygen, which produces radical and reactive oxygen species that kill the cells. However, the immune reaction that occurs following PDT remains unknown. The present study demonstrated that the necrosis of osteosarcoma cells inhibited the function of dendritic cells. However, treatment of osteosarcoma cells with PDT restored the function of dendritic cells by upregulating heat shock protein 70. Taken together, the results of the present study provided insight into the subsequent molecular reaction following PDT treatment of osteosarcoma at the molecular level.

Recent Progress in Metal-Based Nanoparticles Mediated Photodynamic Therapy

Photodynamic therapy (PDT) is able to non-invasively treat and diagnose various cancers and nonmalignant diseases by combining light, oxygen, and photosensitizers (PSs). However, the application of PDT is hindered by poor water solubility and limited light-penetration depth of the currently available photosensitizers (PSs). Water solubility of PSs is crucial for designing pharmaceutical formulation and administration routes. Wavelength of light source at visible range normally has therapeutic depth less than 1 mm. In this review, focus is on the recent research progress of metal-based nanoparticles being applied in PDT. The potential toxicity of these nanoscales and future directions are further discussed.

Pollen-Structured Gold Nanoclusters for X-ray Induced Photodynamic Therapy

Photodynamic therapy (PDT) is a cancer treatment that employs the production of cytotoxic reactive oxygen species (ROS), subsequently triggering tumor apoptosis and tumor size reduction. However, this approach suffers from insufficient light penetration depth. In order to mitigate this issue, pollen-structured gold clusters (PSGCs) were designed for mediating X-ray-induced PDT for radiotherapy enhancement. The structure of PSGCs provides a large surface area that is able to generate ROS upon X-ray irradiation. The synthesized PSGCs were exposed to different X-ray doses and the generated ROS was then quantified by dihydroethidium (DHE) assay. Furthermore, at the cellular level, the PDT efficacy of PSGCs was evaluated via immunofluorescence staining with γ-H2AX and comet assay. The results demonstrated that PSGCs possess a significantly high ROS-generating capacity and a remarkable PDT efficacy in the treatment of breast cancer cells, thus showing potential clinical uses in deep-tissue cancer treatment.

Enhanced sterilization and healing of cutaneous pseudomonas infection using 5-aminolevulinic acid as a photosensitizer with 410-nm LED light

BACKGROUND

Pseudomonas aeruginosa (PA) frequently develops antibiotic-resistant characteristics, which is clinically problematic. The main reason behind the rise of antibiotic-resistant PA is the extensive use of antibiotics. Therefore, a novel technique is needed to treat PA infections. Photodynamic therapy (PDT) is thought to have the potential to be a non-antibiotic treatment for infections. 5-Aminolevulinic acid (ALA), which works as a photosensitizer after being metabolized into protoporphyrin IX (PpIX) in the heme synthetic pathway, is used for PDT. Thus far, the in vivo effectiveness of PDT using ALA against PA is unknown.

OBJECTIVE

In this study, we investigated PDT using ALA both in vitro and in vivo.

METHODS AND RESULTS

Although PDT with ALA alone did not show a bactericidal effect on PA, PDT with both ALA and EDTA-2Na had a bactericidal effect in vitro. In in vivo experiments, wounds healed faster in PA-infected mice treated with PDT using both EDTA-2Na and ALA compared to non-PDT.

CONCLUSION

These results suggest that PDT with EDTA-2Na and ALA is a potential novel treatment option for PA-infected wounds.

Near-Infrared-Light-Activatable Nanomaterial-Mediated Phototheranostic Nanomedicines: An Emerging Paradigm for Cancer Treatment

Cancer is one of the most deadly diseases threatening the lives of humans. Although many treatment methods have been developed to tackle cancer, each modality of cancer treatment has its own limitations and drawbacks. The development of minimally invasive treatment modalities for cancers remains a great challenge. Near-infrared (NIR) light-activated nanomaterial-mediated phototherapies, including photothermal and photodynamic therapies, provide an alternative means for spatially and temporally controlled minimally invasive treatments of cancers. Nanomaterials can serve as nanocargoes for the delivery of chemo-drugs, diagnostic contrast reagents, and organic photosensitizers, and can be used to directly generate heat or reactive oxygen species for the treatment of tumors without the need for organic photosensitizers with NIR-light irradiation. Here, current progress in NIR-light-activated nanomaterial-mediated photothermal therapy and photodynamic therapy is summarized. Furthermore, the effects of size, shape, and surface functionalities of nanomaterials on intracellular uptake, macrophage clearance, biodistribution, cytotoxicities, and biomedical efficacies are discussed. The use of various types of nanomaterials, such as gold nanoparticles, carbon nanotubes, graphene, and many other inorganic nanostructures, in combination with diagnostic and therapeutic modalities for solid tumors, is briefly reviewed.

Pore forming channels as a drug delivery system for photodynamic therapy in cancer associated with nanoscintillators

According to the World Health Organization (WHO), cancer is one of main causes of death worldwide, with 8.2 million people dying from this disease in 2012. Because of this, new forms of treatments or improvement of current treatments are crucial. In this regard, Photodynamic therapy (PDT) has been used to successfully treat cancers that can be easily accessed externally or by fibre-optic endoscopes, such as skin, bladder and esophagus cancers. In addition, this therapy can used alongside radiotherapy and chemotherapy in order to kill cancer cells. The main problem in implementing PDT is penetration of visible light deeper than 10 mm in tissues, due to scattering and absorption by tissue chromophores. Unfortunately, this excludes several internal organs affected by cancer. Another issue in this regard is the use of a selective cancer cell-photosensitizing compound. Nevertheless, several groups have recently developed scintillation nanoparticles, which can be stimulated by X-rays, thereby making this a possible solution for light production in deeper tissues. Alternative approaches have also been developed, such as photosensitizer structure modifications and cell membrane permeabilizing agents. In this context, certain channels lead to transitory plasma membrane permeability changes, such as pannexin, connexin hemmichannels, TRPV1-4 and P2×7, which allow for the non-selective passage of molecules up to 1,000 Da. Herein, we discuss the particular case of the P2×7 receptor-associated pore as a drug delivery system for hydrophilic substances to be applied in PDT, which could also be carried out with other channels. Methylene blue (MB) is a low cost dye used as a prototype photosensitizer, approved for clinical use in several other clinical conditions, as well as photodynamic therapy for fungi infections.

Emerging intravesical drugs for the treatment of non muscle-invasive bladder cancer

INTRODUCTION

Bladder cancer (BC) is a severe health burden: and has high recurrence and progression rates. Standard treatment starts with TURB followed by intravesical chemotherapy with Mitomycin C or immunotherapy with BCG. However, successful management still remains a challenge, because approximately 30% of patients have recurrence or progression within 5 years, and treatment has considerable side effects. Anticipating on the upcoming BCG shortage emphasizes, moreover, the necessity to develop and study novel treatments. This review explores emerging and novel salvage treatments as well as approaches of current treatments with decrease side-effects for non muscle-invasive bladder cancer (NMIBC). Areas covered: In this review, the authors provide an overview of the novel and emerging therapies for NMIBC. They also provide the currently available data and ongoing trials. Expert opinion: Key findings in the field of research on emerging intravesical drugs for the treatment of NMIBC are the promising results for device assisted treatments, treatment with intravesical immunotherapy, and treatments to expedite the immunotherapy checkpoint inhibitors. Other novel therapies are still in an experimental stage and have to make the transition towards the clinical setting to determine the benefit in terms of reduced side-effects, recurrence and progression rates.

Recent advances in nanoparticle carriers for photodynamic therapy

This review summarizes recent advances in the development of nanoparticles (NPs) for efficient photodynamic therapy (PDT), particularly the development and application of various NPs based on organic and inorganic materials. PubMed database was used for literature search with the terms including NP, nanomedicine, PDT, photosensitizer (PSs), and drug delivery. For successful PDT, it is essential to deliver PSs to target disease sites. A number of NPs have been developed and tested as the carriers for both imaging and therapy, an approach termed "nanomedicine". Many studies of NP carriers showed increased water solubility and stability of PSs for in vivo injection, and these NP carriers provided benefits including longer circulation in blood and higher accumulation of PSs at disease sites. This review describes new techniques in PDT such as aggregation-induced emission (AIE) and luminescence-based PDT, and provides insights on NPs and PDT for biomedical researchers working to develop or apply NPs in efficient PDT.

Effect of photodynamic therapy combined with Celecoxib on expression of cyclooxygenase-2 protein in HeLa cells

The present study assessed the effect of photodynamic therapy (PDT) combined with Celecoxib (Cel) on cervical cancer HeLa cells. An MTT assay was performed to detect the inhibitory effects of Cel with different concentrations (10, 50, 100, 150, 200, 250 and 300 µg/ml) on the proliferation of HeLa cells. Subsequently, HeLa cells were divided into control group (group H), 50 g/ml Celecoxib group (group C), PDT group (group P), 50 g/ml Cel + PDT group (group P + C) and western blotting and immunohistochemistry were performed to detect the expression of cyclooxygenase-2 (COX-2) protein in the different groups. Cel inhibited HeLa cells proliferation 24 h following administration, among which 200 µg/ml induced a 50% inhibition rate; the relative expression level of COX-2 protein in group P + C was significantly decreased compared with that in either group C or group P (P<0.05). Cel inhibited the proliferation of human cervical cancer cells in a concentration-dependent manner, and combined PDT therapy may improve treatment outcomes.

Synthesis and in vitro PDT evaluation of new porphyrins containing meso-epoxymethylaryl cationic groups

OBJECTIVES

Photodynamic therapy (PDT) is an effective cancer treatment that uses photosensitizers, light, and oxygen to destroy malignant cells. Porphyrins, and in particular the cationic derivatives, are the most investigated photosensitizers for PDT. In this context, it is important to study new methodologies to develop efficient cationic photosensitizers for use in PDT.

MATERIALS AND METHODS

New porphyrins bearing cationic epoxymethylaryl groups were synthesized and characterized. Their cellular uptake, intracellular localization, and phototoxicity were evaluated in human HEp2 cells, and compared with their methylated analogs.

RESULTS

All cationic porphyrins were efficient generators of singlet oxygen, with quantum yields in the range 0.35-0.61. The two methylated derivatives (3 and 4) accumulated the most within cells at all times investigated, up to 24 hours. Of these two porphyrins, 4 was the most phototoxic to the cells (LD₅₀  = 2.4 μM at 1.5 J/cm² ); however, porphyrin 3 also showed high phototoxicity (LD₅₀  = 7.4 μM at 1.5 J/cm² ). The epoxymethyl-containing porphyrins were found to be less phototoxic than the methylated derivatives, with LD₅₀ > 38 μM. The neutral porphyrins showed no phototoxicity up to the 100 μM concentrations investigated, and had the lowest singlet oxygen quantum yields. All cationic porphyrins localized mainly in the cell ER, Golgi apparatus, and lysosomes.

CONCLUSION

Our results suggest that cationic methylated porphyrin derivatives are promising PDT photosensitizing agents. The epoxymethyl-containing derivatives showed increased efficacy relative to the neutral analogs, and are good candidates for further investigation. Lasers Surg. Med. 50:566-575, 2018. © 2018 Wiley Periodicals, Inc.

Intratumoral depletion of regulatory T cells using CD25-targeted photodynamic therapy in a mouse melanoma model induces antitumoral immune responses

Tumor immunotherapy aims to overcome the immunosuppressive microenvironment within tumors, and various approaches have been developed. Tumor-associated T regulatory cells (Tregs) suppress the activation and expansion of tumor antigen-specific effector T cells, thus, providing a permissive environment for tumor growth. Therefore, optimal strategies need to be established to deplete tumor-infiltrated Tregs because systemic depletion of Tregs can result in reduced anti-tumor effector cells and autoimmunity. Here, to selectively deplete Tregs in tumors, we intratumorally injected anti-CD25 antibodies conjugated to Chlorin e6 (Ce6), a photosensitizer that absorbs light to generate reactive oxygen species. Local depletion of tumor-associated Tregs with photodynamic therapy (PDT) inhibited tumor growth, which was likely due to the altered tumor immune microenvironment that was characterized by increased infiltration of CD8+ effector T cells and the expression of IFN-γ and CD107a, which is a cytolytic granule exocytosis marker in tumor tissues. Furthermore, PDT-induced intratumoral Treg depletion did not influence adaptive immune responses in a murine influenza infection model. Thus, our results show that intratumoral Treg-targeted PDT could specifically modulate tumor microenvironments by depleting Tregs and could be used as a novel cancer immunotherapy technique.

Protoporphyrin IX (PpIX)-Coated Superparamagnetic Iron Oxide Nanoparticle (SPION) Nanoclusters for Magnetic Resonance Imaging and Photodynamic Therapy

The ability to produce nanotherapeutics at large-scale with high drug loading efficiency, high drug loading capacity, high stability, and high potency is critical for clinical translation. However, many nanoparticle-based therapeutics under investigation suffer from complicated synthesis, poor reproducibility, low stability, and high cost. In this work, a simple method for preparing multifunctional nanoparticles is utilized that act as both a contrast agent for magnetic resonance imaging and a photosensitizer for photodynamic therapy for the treatment of cancer. In particular, the photosensitizer protoporphyrin IX (PpIX) is used to solubilize small nanoclusters of superparamagnetic iron oxide nanoparticles (SPIONs) without the use of any additional carrier materials. These nanoclusters are characterized with a high PpIX loading efficiency; a high loading capacity, stable behavior; high potency; and a synthetic approach that is amenable to large-scale production. In vivo studies of photodynamic therapy (PDT) efficacy show that the PpIX-coated SPION nanoclusters lead to a significant reduction in the growth rate of tumors in a syngeneic murine tumor model compared to both free PpIX and PpIX-loaded poly(ethylene glycol)-polycaprolactone micelles, even when injected at 1/8th the dose. These results suggest that the nanoclusters developed in this work can be a promising nanotherapeutic for clinical translation.

Preparation of a chlorophyll derivative and investigation of its photodynamic activities against cholangiocarcinoma

Photodynamic therapy (PDT) is emerging as a promising method for the treatment of various cancer diseases. However, the clinical application of PDT is limited due to the lack of effective photosensitizers. In this study, a novel chlorophyll derivative, N,N-bis(2-carboxyethyl)pyropheophorbide a (BPPA), had been synthesized and characterized. BPPA had a characteristic long wavelength absorption peak at 669nm and a singlet oxygen quantum yield of 0.54. To investigate the photodynamic ability of BPPA against cholangiocarcinoma (CCA), cellular uptake, subcellular location and bio-distribution, in vitro and in vivo PDT efficacy of BPPA were studied. The results showed that BPPA could rapidly accumulate in QBC-939 cells and localize in the cytoplasm. BPPA- PDT was effective in reducing the cell viability in a drug dose- and light dose-dependent manner in vitro. In CCA xenograft nude mouse model, the concentration of BPPA in the plasma lowered rapidly, and the fluorescence signal peaked at 0.5h and 2h after injection in the skin and tumor, respectively. Significant quantities could be observed in the tumor. BPPA followed by irradiation could significantly inhibit growth of tumors, and histological examination revealed necrotic damage in PDT-treated tumors. These results suggested that BPPA could be a promising drug candidate for photodynamic therapy in cholangiocarcinoma.

A next-generation bifunctional photosensitizer with improved water-solubility for photodynamic therapy and diagnosis

Photodynamic therapy (PDT) exploits light interactions and photosensitizers to induce cytotoxic reactive oxygen species. Photodynamic diagnosis (PDD) uses the phenomenon of photosensitizer emitting fluorescence to distinguish some tumors from normal tissue. The standard photosensitizer used for PDD is 5-aminolevulinic acid (5-ALA), although it is not entirely satisfactory. We previously reported glucose-conjugated chlorin (G-chlorin) as a more effective photosensitizer than another widely used photosensitizer, talaporfin sodium (TS); however, G-chlorin is hydrophobic. We synthesized oligosaccharide-conjugated chlorin (O-chlorin) with improved water-solubility. We report herein on its accumulation and cytotoxicity. O-chlorin was synthesized and examined for solubility. Flow cytometric analysis was performed to evaluate O-chlorin accumulation in cancer cells. To evaluate the intracellular localization of photosensitizer, cells were stained with O-chlorin and organelle-specific fluorescent probes. We then measured the in vitro fluorescence of various photosensitizers and the half-maximal inhibitory concentrations to evaluate effects in PDD and PDT, respectively. Xenograft tumor models were established, and antitumor and visibility effects were analyzed. O-chlorin was first shown to be hydrophilic. Flow cytometry then revealed a 20- to 40-times higher accumulation of O-chlorin in cancer cells than of TS, and a 7- to 23-times greater fluorescence than 5-ALA. In vitro, the cytotoxicity of O-chlorin PDT was stronger than that of TS PDT, and O-chlorin tended to accumulate in lysosomes. In vivo, O-chlorin showed the best effect in PDT and PDD compared to other photosensitizers.

O-chlorin was hydrophilic and showed excellent tumor accumulation and fluorescence. O-chlorin is promising as a next-generation bifunctional photosensitizer candidate for both PDT and PDD.

Folate-modified PLGA nanoparticles for tumor-targeted delivery of pheophorbide a in vivo

Targeted drug delivery has been an important issue for tumor therapy including photodynamic therapy (PDT). The purpose of our study is to increase the targeting efficiency of photosensitizer (PS) using folate-modified nanoparticles (NPs) to tumor site in vivo. Folate receptor is over-expressed on the surface of many human cancer cells. We prepared poly (lactic-co-glycolic acid) (PLGA) NPs containing pheophorbide a (Pba), a PS that is used in PDT and generates free radical for killing cancer cells. The surface of NPs was composed of phospholipids modified with polyethylene glycol (PEG) and folate (FA). The size of the resulting FA-PLGA-Pba NPs was about 200 nm in PBS at pH 7.4 and they were stable for long time. They showed faster cellular uptake to MKN28 human gastric cancer cell line than control PLGA-Pba NPs by high-affinity binding with folate receptors on cell surface. In MTT assay, FA-PLGA-Pba NPs also showed enhanced tumor cell killing compared to control PLGA-Pba NPs. In vivo and ex vivo imaging showed high accumulation of FA-PLGA-Pba NPs in tumor site during 24 h after intravenous injection to MKN28 tumor-bearing mice model. These results demonstrate that our FA-PLGA-Pba NPs are useful for tumor-targeted delivery of PS for cancer treatment by PDT.