Photodynamic therapy of skin cancers: sensitizers, clinical studies and future directives

Effectiveness of surgery combined with photodynamic therapy for recurrent respiratory papillomatosis

OBJECTIVE

This study aims to analyze the safety and effectiveness of a new model of surgery combined with Photodynamic therapy for treating Recurrent Respiratory Papillomatosis (RRP).

METHODS

Review the case data of patients with RRP who opted for comprehensive surgery combined with Photodynamic therapy at the Nanjing BenQ Medical Center, from January 2021 to May 2023. The efficacy of this program was evaluated by comparing the annual number of surgeries and Derkay scores before and after the surgery.

RESULTS

A total of 23 RRP patients were included in the study. After treatment, the recurrence rate was 65.2 % (15/23), with an average recurrence time of 94.3 ± 50.8 days. The average Derkay score at the time of recurrence was significantly lower than the average pre-treatment Derkay score (P < 0.001). The average annual recurrence rate before treatment was 2.2 ± 1.3, compared to 1.5 ± 1.5 after treatment, with no significant difference (P = 0.16). However, subgroup analysis revealed a significant decrease in the annual recurrence rate of adult-onset RRP after treatment (P = 0.01). The most common adverse reaction was mild pharyngeal pain (11/23). There were 3 cases of new-onset vocal cord adhesions. No patients experienced serious respiratory-related adverse reactions, anesthesia-related adverse reactions, or systemic phototoxic reactions.

CONCLUSION

In conclusion, this study indicates that surgery combined with Photodynamic therapy (PDT) might be a safe and effective option for treating RRP, especially in patients with Adult-Onset Recurrent Respiratory Papillomatosis (AORRP).

Review of the application of the most current sophisticated image processing methods for the skin cancer diagnostics purposes

This paper presents the most current and innovative solutions applying modern digital image processing methods for the purpose of skin cancer diagnostics. Skin cancer is one of the most common types of cancers. It is said that in the USA only, one in five people will develop skin cancer and this trend is constantly increasing. Implementation of new, non-invasive methods plays a crucial role in both identification and prevention of skin cancer occurrence. Early diagnosis and treatment are needed in order to decrease the number of deaths due to this disease. This paper also contains some information regarding the most common skin cancer types, mortality and epidemiological data for Poland, Europe, Canada and the USA. It also covers the most efficient and modern image recognition methods based on the artificial intelligence applied currently for diagnostics purposes. In this work, both professional, sophisticated as well as inexpensive solutions were presented. This paper is a review paper and covers the period of 2017 and 2022 when it comes to solutions and statistics. The authors decided to focus on the latest data, mostly due to the rapid technology development and increased number of new methods, which positively affects diagnosis and prognosis.

Nanocarriers in topical photodynamic therapy

INTRODUCTION

Photodynamic therapy (PDT) has gained significant attention due to its superiority over conventional treatments. In the context of skin cancers and nonmalignant skin diseases, topical application of photosensitizer formulations onto affected skin, followed by illumination, offers distinct advantages. Topical PDT simplifies therapy by providing easy access to the skin, increasing drug concentration within the target area, and confining residual photosensitivity to the treated skin. However, the effectiveness of topical PDT is often hindered by challenges such as limited skin penetration or photosensitizer instability. Additionally, the hypoxic tumor environment poses further limitations. Nanocarriers present a promising solution to address these challenges.

AREAS COVERED

The objective of this review is to comprehensively explore and highlight the role of various nanocarriers in advancing topical PDT for the treatment of skin diseases. The primary focus is to address the challenges associated with conventional topical PDT approaches and demonstrate how nanotechnology-based strategies can overcome these challenges, thereby improving the overall efficiency and efficacy of PDT.

EXPERT OPINION

Nanotechnology has revolutionized the field of PDT, offering innovative tools to combat the unfavorable features of photosensitizers and hurdles in PDT. Nanocarriers enhance skin penetration and stability of photosensitizers, provide controlled drug release, reduce needed dose, increase production of reactive oxygen species, while reducing side effects, thereby improving PDT effectiveness.

Photodynamic Therapy, Probiotics, Acetic Acid, and Essential Oil in the Treatment of Chronic Wounds Infected with Pseudomonas aeruginosa

As a prevalent medical problem that burdens millions of patients across the world, chronic wounds pose a challenge to the healthcare system. These wounds, often existing as a comorbidity, are vulnerable to infections. Consequently, infections hinder the healing process and complicate clinical management and treatment. While antibiotic drugs remain a popular treatment for infected chronic wounds, the recent rise of antibiotic-resistant strains has hastened the need for alternative treatments. Future impacts of chronic wounds are likely to increase with aging populations and growing obesity rates. With the need for more effective novel treatments, promising research into various wound therapies has seen an increased demand. This review summarizes photodynamic therapy, probiotics, acetic acid, and essential oil studies as developing antibiotic-free treatments for chronic wounds infected with Pseudomonas aeruginosa. Clinicians may find this review informative by gaining a better understanding of the state of current research into various antibiotic-free treatments. Furthermore. this review provides clinical significance, as clinicians may seek to implement photodynamic therapy, probiotics, acetic acid, or essential oils into their own practice.

Combination of Two Photosensitisers in Anticancer, Antimicrobial and Upconversion Photodynamic Therapy

Photodynamic therapy (PDT) is a special form of phototherapy in which oxygen is needed, in addition to light and a drug called a photosensitiser (PS), to create cytotoxic species that can destroy cancer cells and various pathogens. PDT is often used in combination with other antitumor and antimicrobial therapies to sensitise cells to other agents, minimise the risk of resistance and improve overall outcomes. Furthermore, the aim of combining two photosensitising agents in PDT is to overcome the shortcomings of the monotherapeutic approach and the limitations of individual agents, as well as to achieve synergistic or additive effects, which allows the administration of PSs in lower concentrations, consequently reducing dark toxicity and preventing skin photosensitivity. The most common strategies in anticancer PDT use two PSs to combine the targeting of different organelles and cell-death mechanisms and, in addition to cancer cells, simultaneously target tumour vasculature and induce immune responses. The use of PDT with upconversion nanoparticles is a promising approach to the treatment of deep tissues and the goal of using two PSs is to improve drug loading and singlet oxygen production. In antimicrobial PDT, two PSs are often combined to generate various reactive oxygen species through both Type I and Type II processes.

Advances in Liposome-Encapsulated Phthalocyanines for Photodynamic Therapy

This updated review aims to describe the current status in the development of liposome-based systems for the targeted delivery of phthalocyanines for photodynamic therapy (PDT). Although a number of other drug delivery systems (DDS) can be found in the literature and have been studied for phthalocyanines or similar photosensitizers (PSs), liposomes are by far the closest to clinical practice. PDT itself finds application not only in the selective destruction of tumour tissues or the treatment of microbial infections, but above all in aesthetic medicine. From the point of view of administration, some PSs can advantageously be delivered through the skin, but for phthalocyanines, systemic administration is more suitable. However, systemic administration places higher demands on advanced DDS, active tissue targeting and reduction of side effects. This review focuses on the already described liposomal DDS for phthalocyanines, but also describes examples of DDS used for structurally related PSs, which can be assumed to be applicable to phthalocyanines as well.

Influence of Green Synthesized Zinc Oxide Nanoparticles on Molecular Interaction and Comparative Binding of Azure Dye with Chymotrypsin: Novel Nano-Conjugate for Cancer Phototherapy

Till date, different types of conventional drugs have been used to fight tumors. However, they have significant flaws, including their usage being constrained because of their low bioavailability, poor supply, and serious side effects. The modern combination therapy has been viewed as a potent strategy for treating serious illnesses, including cancer-type feared diseases. The nanoparticles are a promising choice for cancer therapeutic and diagnostic applications because of their fascinating optoelectronic and physicochemical features. Among the metallic nanoparticles, Zinc oxide nanoparticles possess interesting physicochemical and anti-cancer characteristics, such as ROS generation, high retention, enhanced permeability etc., making them attractive candidates for the treatment and diagnosis of cancer. Zinc oxide nanoparticles showed anti-cancer property via excessive reactive oxygen species (ROS) production, and by the destruction of mitochondrial membrane. Here, we have synthesized organic/inorganic hybrid nanosystem composed of chymotrypsin protein (Chymo) with AzureC (AzC) conjugated with Zinc oxide nanoparticles (ZnONPs). The conjugation of AzureC with ZnONPs was confirmed by transmission electron microscopy (TEM), zeta potential, and dynamic light scattering (DLS) experiment. The interaction of Chymo with AzC alone and AzC-ZnONPs was investigated, and it was observed that the interaction was enhanced in the presence of ZnONPs, which was concluded by the results obtained from different spectroscopic techniques such as UV-Visible spectroscopy, fluorescence spectroscopy and circular dichroism in combination with molecular docking. UV-Visible spectroscopic studies and the corresponding binding parameters showed that the binding of AzC-ZnONPs complex with Chymo is much higher than that of AzC alone. Moreover, the fluorescence measurement showed enhancement in static quenching during titration of Chymo with AzC-ZnONPs as compared to dye alone. In addition to this, circular dichroism results show that the dye and dye-NPs conjugate do not cause much structural change in α-Chymo. The molecular docking and thermodynamic studies showed the predominance of hydrogen bonding, Van der Waal force, and hydrophobic forces during the interactions. After correlation of all the data, interaction of Chymo with AzC-ZnONPs complex showed strong interaction as compared to dye alone. The moderate binding with chymo without any alteration in the structure makes it desirable for the distribution and pharmacokinetics. In addition, the in vitro cytotoxicity of the AzC-ZnONPs was demonstrated on A-549 adenocarcinoma cell line. Our findings from physiochemical investigations suggested that the chymotrypsin coated AzC conjugated ZnONPs could be used as the novel nanoconjugates for various cancer phototherapies.

Topical methylene blue nanoformulation for the photodynamic therapy of acne vulgaris

Acne vulgaris is a common skin disease caused by multifactorial reasons involving excessive sebum secretion and inflammation by Cutibacterium acnes (C. acnes). Various conventional therapies are available for the treatment of acne vulgaris; however, topical photodynamic therapy (PDT) has attracted much attention because of its great potential for sebum-reducing, anti-inflammatory, and antimicrobial activities. Although 5-aminolevulinic acid (ALA) has been broadly used as a photosensitizer for topical PDT, it has several limitations such as long incubation time, pain, and post-inflammatory hyperpigmentation. Here, we report a biocompatible nanoformulation consisting of methylene blue and salicylic acid (MBSD), as a potent PDT and acne therapeutics, enclosed within oleic acid. Photoactivated MBSD showed antimicrobial activity against C. acnes along with long-term stability. When 24 patients with acne were treated with MBSD and light irradiation 5 times at 1-week intervals, MBSD-based PDT exhibited a remarkable reduction in acne lesions and sebum production. In addition, the therapeutic procedure was painless and safe, without any adverse events. Therefore, MBSD is a promising topical PDT agent for biocompatible, safe, and effective acne treatment.

An Analysis of the Effects of In Vitro Photodynamic Therapy on Prostate Cancer Tissue by Histopathological Examination and Magnetic Resonance Imaging

Prostate cancer can significantly shorten the lifetime of a patient, even if he is diagnosed at an early stage. The development of minimally-invasive focal therapies such as photodynamic therapy to reduce the number of neoplastic cells while sparing delicate structures is extremely advantageous for treating prostate cancer. This study investigates the effect of photodynamic therapy performed in prostate tissue samples in vitro, using quantitative magnetic resonance imaging and histopathological analysis. Prostate tissue samples were treated with oxygenated solutions of Rose Bengal (RB) or protoporphyrin IX disodium salt (PpIX), illuminated with visible light, and then analyzed for changes in morphology by microscopy and by measurement of spin–lattice and spin–spin relaxation times at 1.5 Tesla. In the treated prostate tissue samples, histopathological images revealed chromatin condensation and swelling of the stroma, and in some cases, thrombotic necrosis and swelling of the stroma accompanied by pyknotic nuclei occurred. Several samples had protein fragments in the stroma. Magnetic resonance imaging of the treated prostate tissue samples revealed differences in the spin–lattice and spin–spin relaxation times prior to and post photodynamic action.

5-Aminolevulinic Acid-Hyaluronic Acid Complexes Enhance Skin Retention of 5-Aminolevulinic Acid and Therapeutic Efficacy in the Treatment of Hypertrophic Scar

Hypertrophic scar is a serious skin disorder, which reduces the patient's quality of life. 5-aminolevulinic acid (5-ALA)-mediated photodynamic therapy has been used to treat patients with hypertrophic scar. However, the poor skin retention of 5-ALA limited the therapeutic effect. In this study, we constructed the 5-ALA-hyaluronic acid (HA) complex to potentially prolong the skin retention of 5-ALA for improving the therapeutic efficacy. HA is a polysaccharide with viscoelasticity and the carboxyl groups could conjugate with amino groups of 5-ALA via electrostatic interaction. The protoporphyrin IX (PpIX) assay revealed that 5-ALA-HA complexes markedly enhanced the skin retention, resulting in increased generation and accumulation of endogenous photosensitizer PpIX. Furthermore, 5-ALA-HA complexes allowed PpIX to be maintained at a high level for 12 h, much longer than the 3 h of 5-ALA alone. And then, the accumulative PpIX induced by 5-ALA-HA in human hypertrophic scar fibroblasts (HSF) was triggered by laser irradiation to produce sufficient reactive oxygen species, leading to efficient necrosis and apoptosis of HSF. In vivo therapeutic efficacy study indicated that 5-ALA-HA effectively reduced the appearance and scar thickness, and the scar elevation index with 5-ALA-HA treatment was significantly lower than other groups, suggesting that the 5-ALA-HA-treated scar became flattened and was closely matched to the unwounded tissues. Moreover, 5-ALA-HA treatment markedly downregulated the gene expression levels of α-SMA and TGF-β1, demonstrating attenuated the scar formation and growth. Therefore, the 5-ALA-HA complex enhancing skin retention and PpIX accumulation at the lesion site provide a promising therapeutic strategy for hypertrophic scar.

Tissue Engineering and Photodynamic Therapy: A New Frontier of Science for Clinical Application -An Up-To-Date Review

Tissue engineering (TE) connects principles of life sciences and engineering to develop biomaterials as alternatives to biological systems and substitutes that can improve and restore tissue function. The principle of TE is the incorporation of cells through a 3D matrix support (scaffold) or using scaffold-free organoid cultures to reproduce the 3D structure. In addition, 3D models developed can be used for different purposes, from studies mimicking healthy tissues and organs as well as to simulate and study different pathologies. Photodynamic therapy (PDT) is a non-invasive therapeutic modality when compared to conventional therapies. Therefore, PDT has great acceptance among patients and proves to be quite efficient due to its selectivity, versatility and therapeutic simplicity. The PDT mechanism consists of the use of three components: a molecule with higher molar extinction coefficient at UV-visible spectra denominated photosensitizer (PS), a monochromatic light source (LASER or LED) and molecular oxygen present in the microenvironment. The association of these components leads to a series of photoreactions and production of ultra-reactive singlet oxygen and reactive oxygen species (ROS). These species in contact with the pathogenic cell, leads to its target death based on necrotic and apoptosis ways. The initial objective of PDT is the production of high concentrations of ROS in order to provoke cellular damage by necrosis or apoptosis. However, recent studies have shown that by decreasing the energy density and consequently reducing the production of ROS, it enabled a specific cell response to photostimulation, tissues and/or organs. Thus, in the present review we highlight the main 3D models involved in TE and PS most used in PDT, as well as the applications, future perspectives and limitations that accompany the techniques aimed at clinical use.

Hypericin-mediated photodynamic therapy enhances gemcitabine induced Capan-2 cell apoptosis via inhibiting NADPH level

OBJECTIVES

The combination of gemcitabine (Gem) and hypericin (HY) enhances the apoptosis of Capan-2 cells, providing a promising option for the treatment of pancreatic cancer. Our study further explored the cytotoxic mechanism of HY combined with chemotherapy drugs on pancreatic cancer.

METHODS

The proliferation rate of the cells assayed with the MTT method. The ROS (reactive oxygen species) levels of each treatment were evaluated by DCFH-DA oxidisation methods. The activity of glutathione reductase and the levels of reduced glutathione (GSH) and oxidised glutathione (GSSG) were assessed using assay kits. The expression levels of apoptosis-related proteins were analysed by western blotting.

KEY FINDINGS

The activity of glucose-6-phosphate dehydrogenase (G6PDH), a key enzyme of the pentose phosphate pathway, significantly decreased in Gem + HY groups, however, the ROS level enhanced accompanying with GSH depleting, mitochondrial membrane depolarisation and cytochrome C release. Gem + HY inhibits the expression of Bcl-2 but stimulates Bax level, triggering caspase activation and PARP cleavage and thus promoted apoptosis of Capan-2 cells.

CONCLUSIONS

We demonstrated that Gem combined HY-PDT could inhibit the proliferation of Capan-2 cells and induce cell apoptosis. HY-PDT combined with Gem had a great potential on pancreatic cancer treatment clinically.

A scintillating nanoplatform with upconversion function for the synergy of radiation and photodynamic therapies for deep tumors

Collaborative therapy is regarded as an effective approach in increasing the therapeutic efficacy of cancer. In this work, we have proposed and validated the concept of upconversion lumienscence image guided synergy of photodynamic therapy (PDT) and radiotherapy (RT) for deep cancer, via a specially designed nanoplatform integrating near infrared (NIR) light activated luminescence upconversion and X-ray induced scintillation. Upon NIR light irradiation, the nanoplatform emits highly monochromatic red light solely for imaging the targeted cancer cells without triggering therapy; however, when the irradiation turns to a low dose of X-rays, scintillation will occur which induces effectively the PDT destroying the cancer cells together with X-ray induced RT. The novel theranostic nanoplatform is constructed in such a way that the interactions between the upconversion core and the outmost scintillating shell are blocked effectively by an inert layer between them. This structural design not only enables a nearly perfect excitation energy delivery (∼100% at a spectral overlapping wavelength of ∼540 nm) from the outermost scintellating layer to the surface-anchored photosensitizers and so a maximum yield of radical oxygen species, but also achieves a strong NIR induced upconversion luminescence for imaging. Since PDT and RT attack different parts of a cancer cell, this synergy is more effective in destroying cancer than a single therapy, resulting in the reduction of the X-ray irradiation dosage. As a proof of principle, the theranostic effect is validated by in vitro and in vivo experiments, exhibiting the great potential of this sort of nanoplatform in deep cancer treatment.

Current Status of Photodynamic Diagnosis for Gastric Tumors

Although the recent development and widespread use of image-enhanced endoscopy and magnifying endoscopy have improved endoscopic diagnosis of gastric cancer, it is somewhat complicated, requires a higher level of expertise, and is still subjective. Photodynamic endoscopic diagnosis (PDED) is based on the fluorescence of photosensitizers that accumulate in tumors, which enables objective evaluation independent of the endoscopist’s experience, and is useful for tumor detection. The objective of this work was to perform a narrative review of PDED for gastric tumors and to introduce our approach to PDED in gastric tumors in our hospital. In our review there have been case reports of PDED for gastric cancer, but its usefulness has not been established because no prospective studies evaluating its usefulness have been performed. In our previous study, 85.7% (42/49) of gastric tumors exhibited fluorescence in PDED. PDED may be useful in the diagnosis of early gastric cancer. Our previous studies were pilot studies in cancer patients; therefore, future prospective studies are required to verify the usefulness of PDED.

Phonosurgery: A review of current methodologies

Cold-steel has served as the gold standard modality of phonosurgery for most of its history. Surgical laser technology has revolutionized this field with its wide use of applications. Additional modalities have also been introduced such as coagulative lasers, photodynamic therapy, and cryotherapy. This review will compare the surgical modalities of cold steel, surgical lasers, phototherapy and cryotherapy. The mechanism of action, tissue effects and typical uses will be addressed for each modality.

Characterization of autofluorescence and quantitative protoporphyrin IX biomarkers for optical spectroscopy-guided glioma surgery

5-Aminolevulinic acid (5-ALA)-mediated fluorescence does not effectively depict low grade gliomas (LGG) or the infiltrative tumor portion of high-grade gliomas (HGG). While spectroscopy improves sensitivity and precision, this is currently limited by autofluorescence and a second protoporphyrin IX (PpIX) fluorescence state at 620 nm. We investigated the autofluorescence to better characterize the present spectra and thus increase PpIX quantification precision and sensitivity. This study included 128 patients undergoing surgery for malignant glioma. 5-ALA (Gliolan) was administered before anesthesia, and fluorescence was measured using a hyperspectral device. It was found that all 2692 measured spectra consisted of contributions from 620 to 634 nm PpIX, NADH, lipofuscin, and flavins. The basis spectra were characterized and their use in spectral unmixing led to 82.4% lower fitting error for weakly fluorescing areas (p < 0.001), and 92.3% fewer false positive tumor identifications in control measurements (p = 0.0065) compared to previous works. They also decreased the PpIX₆₂₀ contribution, thus halving the mean Ratio_620/634 (p < 0.001). The ratio was approximately 0 for HGGs and increasing for LGGs, as demonstrated previously. Additionally, the Ratio_620/634, the MIB-1/Ki-67 proliferation index, and the PpIX peak blue-shift were found to be significantly related to WHO grade, fluorescence visibility, and PpIX contribution (p < 0.001), and the value of these three as quantitative biomarkers is discussed.

Hypericin Enhances Paclitaxel-Induced B16-F10 Cell Apoptosis by Activating a Cytochrome c Release-Dependent Pathway

The enhanced inhibitory effect of paclitaxel (PTX) combined with hypericin (HY) on B16-F10 cells may be realized through the ROS-related cytochrome c release pathway. The apoptotic characteristics of the B16-F10 cells, such as DNA fragmentation, chromatin condensation, and apoptotic body formation, were all enhanced in the combined treatment group. Further investigation showed that the combination of paclitaxel and HY could increase the level of mitochondrial damage and the concentration of cytochrome c, causing the expression of caspase-3 and the cleavage of PARP.¹. Compared with paclitaxel or HY alone, the level of reactive oxygen species (ROS) increased significantly, while glutathione reductase (GR) activity and intracellular glutathione (GSH) levels decreased significantly in the combination group.

Micro- and Nano-Based Transdermal Delivery Systems of Photosensitizing Drugs for the Treatment of Cutaneous Malignancies

Photodynamic therapy is one of the more unique cancer treatment options available in today’s arsenal against this devastating disease. It has historically been explored in cutaneous lesions due to the possibility of focal/specific effects and minimization of adverse events. Advances in drug delivery have mostly been based on biomaterials, such as liposomal and hybrid lipoidal vesicles, nanoemulsions, microneedling, and laser-assisted photosensitizer delivery systems. This review summarizes the most promising approaches to enhancing the photosensitizers’ transdermal delivery efficacy for the photodynamic treatment for cutaneous pre-cancerous lesions and skin cancers. Additionally, discussions on strategies and advantages in these approaches, as well as summarized challenges, perspectives, and translational potential for future applications, will be discussed.

Exploring the Role of Phytochemicals as Potent Natural Photosensitizers in Photodynamic Therapy

BACKGROUND

Cancer is still considered a deadly disease worldwide due to difficulties in diagnosis, painful treatment procedures, costly therapies, side effects, and cancer relapse. Cancer treatments using conventional methods like chemotherapy and radiotherapy were not convincing due to its post-treatment toxicity in the host. In Photodynamic Therapy (PDT), three individual non-toxic components including a photosensitizer, light source and oxygen cause damage to the cells and tissues when they are combined.

OBJECTIVE

In recent years, phytochemicals are being increasingly recognized as potent complementary drugs for cancer because of its natural availability, less toxicity and therapeutic efficiency in par with commercial drugs. Hence, the idea of using phytochemicals as natural photosensitizers in PDT resulted in a multiple pool of research studies with promising results in preclinical and clinical investigations.

METHODS

In this review, the potential of phytochemicals to act as natural photosensitizers for PDT, their mode of action, drawbacks, challenges and possible solutions are discussed in detail.

RESULTS

In PDT, natural photosensitizers, when used alone or in combination with other photosensitizers, induced cell death by apoptosis and necrosis, increased oxidative stress, altered cancer cell death signaling pathways, increased cytotoxicity and DNA damage in cancer cells. The pro-oxidant nature of certain antioxidant polyphenols, hormesis phenomenon, Warburg effect and DNA damaging potential plays a significant role in the photosensitizing mechanism of phytochemicals in PDT.

CONCLUSION

This review explores the role of phytochemicals that can act as photosensitizers alone or in combination with PDT and its mechanism of action on different cancers.

Developments in Vascular-Targeted Photodynamic Therapy for Urologic Malignancies

With improved understanding of cancer biology and technical advancements in non-invasive management of urological malignancies, there is renewed interest in photodynamic therapy (PDT) as a means of focal cancer treatment. The application of PDT has also broadened as a result of development of better-tolerated and more effective photosensitizers. Vascular-targeted PDT (VTP) using padeliporfin, which is a water-soluble chlorophyll derivative, allows for tumor-specific cytotoxicity and has demonstrated efficacy in the management of urologic malignancies. Herein, we describe the evolution of photodynamic therapy in urologic oncology and the role of VTP in emerging treatment paradigms.

Key transporters leading to specific protoporphyrin IX accumulation in cancer cell following administration of aminolevulinic acid in photodynamic therapy/diagnosis

The administration of aminolevulinic acid allow the formation and accumulation of protoporphyrin IX specifically in cancer cells, which then lead to photocytotoxicity following light irradiation. This compound, when accumulated at high levels, could also be used in cancer diagnosis as it would emit red fluorescence when being light irradiated. The concentration of protoporphyrin IX is pivotal in ensuring the effectiveness of the therapy. Studies have been carried out and showed the importance of various transporters in regulating the amount of these substrates by controlling the transport of various related metabolites in and out of the cell. There are many transporters involved and their expression levels are dependent on various factors, such as oxygen availability and iron ions. It is also important to note that these transporters may also have different expression levels depending on their organ. Understanding the mechanisms and the roles of these transporters are essential to ensure maximum accumulation of protoporphyrin IX, leading to higher efficiency in photodynamic therapy/diagnosis. In this review, we would like to discuss the roles of various transporters in protoporphyrin IX accumulation and how their involvement directly affect cancerous microenvironment.

Cannabinoids in the Pathophysiology of Skin Inflammation

Cannabinoids are increasingly-used substances in the treatment of chronic pain, some neuropsychiatric disorders and more recently, skin disorders with an inflammatory component. However, various studies cite conflicting results concerning the cellular mechanisms involved, while others suggest that cannabinoids may even exert pro-inflammatory behaviors. This paper aims to detail and clarify the complex workings of cannabinoids in the molecular setting of the main dermatological inflammatory diseases, and their interactions with other substances with emerging applications in the treatment of these conditions. Also, the potential role of cannabinoids as antitumoral drugs is explored in relation to the inflammatory component of skin cancer. In vivo and in vitro studies that employed either phyto-, endo-, or synthetic cannabinoids were considered in this paper. Cannabinoids are regarded with growing interest as eligible drugs in the treatment of skin inflammatory conditions, with potential anticancer effects, and the readiness in monitoring of effects and the facility of topical application may contribute to the growing support of the use of these substances. Despite the promising early results, further controlled human studies are required to establish the definitive role of these products in the pathophysiology of skin inflammation and their usefulness in the clinical setting.

Nanocarriers in photodynamic therapy-in vitro and in vivo studies

Photodynamic therapy (PDT) is a minimally invasive technique which has proven to be successful in the treatment of several types of tumors. This relatively simple method exploits three inseparable elements: phototoxic compound (photosensitizer [PS]), light source, and oxygen. Upon irradiation by light with specified wavelength, PS generates reactive oxygen species, which starts the cascade of reactions leading to cell death. The positive therapeutic outcome of PDT may be limited due to several aspects, including low water solubility of PSs, hampering their effective administration and blood circulation, as well as low tumor specificity, inefficient cellular uptake and activation energies requiring prolonged illumination times. One of the promising approaches to overcome these obstacles involves the use of carrier systems modulating pharmacokinetics and pharmacodynamics of the PSs. In the present review, we summarized current in vitro and in vivo studies regarding the use of nanoparticles as potential delivery devices for PSs to enhance their cellular uptake and cytotoxic properties, and thus-the therapeutic outcome of PDT. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Fabrication of H2O2-driven nanoreactors for innovative cancer treatments

The increased production of hydrogen peroxide (H₂O₂) is a typical feature of cancerous cells. This feature is closely associated with elevated oxidative stress inside solid tumour microenvironments, which thus impairs either the growth of cancer cells or their sensitivity to many cancer therapeutics. To date, numerous innovative strategies that target tumour H₂O₂ have been designed for effective cancer treatment. More recently, with the rapid advancement of nanomedicine, several nanoreactors, which are highly efficient in converting endogenous H₂O₂ to more toxic reactive oxygen species, promoting in situ H₂O₂, or decomposing endogenous H₂O₂ to molecular oxygen for tumour hypoxia attenuation, have been designed and attempted for effective cancer treatment. This review focuses on the latest progress of such innovative H₂O₂-driven nanoreactor-mediated cancer treatments. Afterwards, future perspectives on the development of tumour H₂O₂-driven nanoreactor-mediated cancer treatments and their potential clinical translations will be discussed.

Investigation of PPIX-Lipo-MnO2 to enhance photodynamic therapy by improving tumor hypoxia

The efficacy of photodynamic therapy (PDT) is reduced in the context of hypoxic environments. This is problematic, considering that hypoxia is exhibited in the vast majority of malignant tumors. Thus, increasing the concentration of oxygen in malignant tumors improves PDT treatment outcomes. Studies show that MnO₂ nanoparticles can produce oxygen when it reacts with endogenous H₂O₂. Herein, we encapsulated Protoporphyrin IX (PPIX) in the liposome bilayer (PPIX-Lipo), which was then coated with MnO₂ nanoparticles to construct PPIX-Lipo-MnO₂ (PPIX-Lipo-M) in order to enhance PDT efficacy under tumor hypoxia. The PDT results show that PPIX-Lipo-M was more cytotoxic to breast cancer cells than PPIX-Lipo while under hypoxic conditions, indicating that the production of oxygen gas in hypoxic conditions improved treatment outcomes. Upon encapsulating PPIX into the liposome, the aqueous solubility of PPIX significantly improved. Consequently, the cellular uptake of both PPIX-Lipo and PPIX-Lipo-M also increased significantly compared to that of bare PPIX. Overall, PPIX-Lipo-M has the capacity to act as a therapeutic agent that relieves hypoxia and hence improve PDT efficacy.

Light-triggered release of photocaged therapeutics - Where are we now?

The current available therapeutics face several challenges such as the development of ideal drug delivery systems towards the goal of personalized treatments for patients benefit. The application of light as an exogenous activation mechanism has shown promising outcomes, owning to the spatiotemporal confinement of the treatment in the vicinity of the diseased tissue, which offers many intriguing possibilities. Engineering therapeutics with light responsive moieties have been explored to enhance the bioavailability, and drug efficacy either in vitro or in vivo. The tailor-made character turns the so-called photocaged compounds highly desirable to reduce the side effects of drugs and, therefore, have received wide research attention. Herein, we seek to highlight the potential of photocaged compounds to obtain a clear understanding of the mechanisms behind its use in therapeutic delivery. A deep overview on the progress achieved in the design, fabrication as well as current and possible future applications in therapeutics of photocaged compounds is provided, so that novel formulations for biomedical field can be designed.

A repertoire of biomedical applications of noble metal nanoparticles

The emerging properties of noble metal nanoparticles are attracting huge interest from the translational scientific community. In this feature article, we highlight recent advances in the adaptation of noble metal nanomaterials and their biomedical applications in therapeutics, diagnostics and sensing.

Photodynamic therapy in endodontics

Photodynamic therapy (PDT) is a treatment modality that was initiated in 1900; however, it was not until the last decade that PDT regained attention for its several favourable features during the treatment of microbial infections in endodontics. Recently, several papers advocated its use for root canal treatment. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near-infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components and consequently produce cell inactivation and death. Recently, PDT has been suggested as a promising effective adjunct to standard antimicrobial intracanal cleaning and shaping for the treatment of periapical lesions. Current publications tested PDT in terms of bacterial load reduction in vivo, in vitro and ex vivo, showing promising results. The purpose of this article was to review the existing literature on PDT in the endodontic field regarding its mechanism of action, photosensitizers and light sources, limitations and clinical procedures. Although positive results have been demonstrated in vitro, there are considerably fewer in vivo investigations. In conclusion, more in vivo studies are needed on the use of antimicrobial PDT in root canal treatment.

Linker chemistry dictates the delivery of a phototoxic organometallic rhenium(i) complex to human cervical cancer cells from core crosslinked star polymer nanoparticles

We have investigated core-crosslinked star polymer nanoparticles designed with tunable release chemistries as potential nanocarriers for a photoactive Re(i) organometallic complex. The nanoparticles consisted of a brush poly(oligo-ethylene glycol)methyl ether acrylate (POEGA) corona and a cross-linked core of non-biodegradable N,N'-methylenebis(acrylamide) (MBAA) and either pentafluorophenyl acrylate (PFPA), 3-vinyl benzaldehyde (VBA) or diacetone acrylamide (DAAM). Each star was modified with an amine functionalized photodynamic agent (i.e. a rhenium(i) organometallic complex) resulting in the formation of either a stable amide bond (POEGA-star-PFPA), or hydrolytically labile aldimine (POEGA-star-VBA) or ketimine bonds (POEGA-star-DAAM). These materials revealed linker dependent photo- and cytotoxicity when tested in vitro against non-cancerous lung fibroblast MRC-5 cells and HeLa human cervical cancer cells: the toxicity results correlated with final intracellular Re concentrations.

The Effect of Quorum-Sensing and Efflux Pumps Interactions in Pseudomonas aeruginosa Against Photooxidative Stress

Resistant infections essentially cause mortality in a burn unit. Several bacteria contribute to burn infections; among these, Pseudomonas aeruginosa majorly contributes to these infections revealing significant drug resistance. Similar to other bacteria, P. aeruginosa reveals various mechanisms to attain highest pathogenicity and resistance; among these, efflux pumps and quorum sensing are crucial. Quorum sensing enables effective communication between bacteria and synchronizes their gene expression resulting in optimum effect of the secreted proteins; alternatively, efflux pumps increase the bacterial resistance by pumping out the antimicrobial factors as well as the QS signals and precursors. Of recent, increasing episodes of drug resistance led to new findings and approaches for killing pathogenic bacteria without inducing the drug-resistant species. Photodynamic therapy (PDT), considered as an adjuvant and innovative method for conventional antibiotic therapy, is a photochemical reaction that includes visible light, oxygen, and a photosensitizer (PS). In this therapy, after exposure to visible light, the PS generates reactive oxygen species (ROS) that are bacteriostatic or bactericidal. Furthermore, this oxidative stress can disrupt the coordination of gene expression and alter the bacterial behavior. Considering the fact that the adaption and several gene expression patterns of microorganisms within the biofilm make them notably resistant to the recent antimicrobial treatments, this study aimed to emphasize the relationship between the efflux pump and QS under oxidative stress and their role in P. aeruginosa's reaction to PDT.

Photodynamic therapy - mechanisms, photosensitizers and combinations

Photodynamic therapy (PDT) is a modern and non-invasive form of therapy, used in the treatment of non-oncological diseases as well as cancers of various types and locations. It is based on the local or systemic application of a photosensitive compound - the photosensitizer, which is accumulated in pathological tissues. The photosensitizer molecules absorb the light of the appropriate wavelength, initiating the activation processes leading to the selective destruction of the inappropriate cells. The photocytotoxic reactions occur only within the pathological tissues, in the area of photosensitizer distribution, enabling selective destruction. Over the last decade, a significant acceleration in the development of nanotechnology has been observed. The combination of photosensitizers with nanomaterials can improve the photodynamic therapy efficiency and eliminate its side effects as well. The use of nanoparticles enables achievement a targeted method which is focused on specific receptors, and, as a result, increases the selectivity of the photodynamic therapy. The object of this review is the anticancer application of PDT, its advantages and possible modifications to potentiate its effects.

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.

Topical formulations of delta-aminolevulinic acid for the treatment of actinic keratosis: Characterization and efficacy evaluation

Actinic keratosis (AK) is a pre-cancerous disease, with worldwide increasing incidence, which consists in squamous cutaneous lesion caused by excessive exposure to ultraviolet radiation. An established treatment option is photodynamic therapy (PDT), based on light, oxygen and a photosensitizer. The most widely used is 5-aminolevulinic acid (ALA) which however, being a hydrophilic molecule, has difficultly penetrating the skin to achieve the desired therapeutic effect. To solve this limit, the present study provides for the development of three galenic gel formulations (Natrosol, Sepigel and Carbopol) containing 10% w/w of ALA for the treatment of AK with PDT and their comparison with a lipophilic cream used in the Hospital. The aim of this study is to offer an appealing topical treatment that improves patients' observance and compliance. Formulations were characterized in terms of chemical, physical and microbiological stability, viscosity and pH. An HPLC-DAD analytical method was also developed and validated. Sepigel gel resulted the best gel formulation in terms of technological characteristics and stability. A comparative study between this gel and the lipophilic cream was assessed, by evaluating the therapeutic efficacy and the compliance of the patients.

Photosensitizers in prostate cancer therapy

The search for new therapeutics for the treatment of prostate cancer is ongoing with a focus on the balance between the harms and benefits of treatment. New therapies are being constantly developed to offer treatments similar to radical therapies, with limited side effects. Photodynamic therapy (PDT) is a promising strategy in delivering focal treatment in primary as well as post radiotherapy prostate cancer. PDT involves activation of a photosensitizer (PS) by appropriate wavelength of light, generating transient levels of reactive oxygen species (ROS). Several photosensitizers have been developed with a focus on treating prostate cancer like mTHPC, motexafin lutetium, padoporfin and so on. This article will review newly developed photosensitizers under clinical trials for the treatment of prostate cancer, along with the potential advantages and disadvantages in delivering focal therapy.

Pyrazole appended quinoline-BODIPY based arene ruthenium complexes: their anticancer activity and potential applications in cellular imaging

Synthesis of four arene ruthenium complexes [Ru(η⁶-C₆H₆)(L1)Cl]PF₆, (1), [Ru(η⁶-C₁₀H₁₄)(L1)Cl]PF₆ (2), [Ru(η⁶-C₆H₆)(L2)Cl]PF₆ (3) and [Ru(η⁶-C₁₀H₁₄)(L2)Cl]PF₆ (4) based on quinoline-BODIPY were described and their photocytotoxicity was evaluated.

Investigation of Copper Cysteamine Nanoparticles as a New Type of Radiosensitiers for Colorectal Carcinoma Treatment

Copper Cysteamine (Cu-Cy) is a new photosensitizer and a novel radiosensitizer that can be activated by light, X-ray and microwave to produce singlet oxygen for cancer treatment. However, the killing mechanism of Cu-Cy nanoparticles on cancer cells is not clear yet and Cu-Cy nanoparticles as novel radiosensitizers have never been tested on colorectal cancers. Here, for the first time, we investigate the treatment efficiency of Cu-Cy nanoparticles on SW620 colorectal cells and elucidate the underlying mechanisms of the effects. The results show that X-ray activated Cu-Cy nanoparticles may kill SW620 cancerscells is in a dose-dependent manner. The JC-1 staining shows the mitochondrial membrane potential is decreased after the treatment. The observations confirm that Cu-Cy nanoparticles may improve X-ray radiotherapy on cancer treatment and X-ray activated Cu-Cy nanoparticles can be efficiently destroy colorectal cancer cells by inducing apoptosis as well as autophagy. As a new type of radiosensitizers and photosensitizers, Cu-Cy nanoparticles have a good potential for colorectal cancer treatment and the discovery of autophagy induced by X-ray irradiated Cu-Cy nanoparticles sheds a good insight to the mechanism of Cu-Cy for cancer treatment as a new radiosensitizers.

Brazilian Green Propolis Extract Synergizes with Protoporphyrin IX-mediated Photodynamic Therapy via Enhancement of Intracellular Accumulation of Protoporphyrin IX and Attenuation of NF-κB and COX-2

Brazilian green propolis (BGP) is noted for its impressive antitumor effects and has been used as a folk medicine in various cultures for many years. It has been demonstrated that BGP could enhance the cytotoxic effect of cytostatic drugs on tumor cells. Photodynamic therapy (PDT) is a therapeutic approach used against malignant cells. To assess the synergistic effect of BGP extract on protoporphyrin IX (PpIX)-mediated photocytotoxicity, MTT assays were performed using A431 and HeLa cells. TUNEL assay and Annexin V-FITC/PI staining were performed to confirm the induction of apoptosis. Western blotting analysis was performed to examine the pro-apoptotic proteins, anti-apoptotic proteins and inflammation related proteins in A431 cells. Intracellular accumulation of PpIX was examined by flow cytometry. The synergistic effect of BGP extract in PpIX-PDT was also evaluated with a xenograft model. Our findings reveal that BGP extract increased PpIX-mediated photocytotoxicity in A431 and HeLa cells. PpIX-PDT with BGP extract treatment resulted in a decrease in Bcl-xL and an increase in NOXA, Bax and caspase-3 cleavage. The protein expression levels of p-IKKα/β, NF-κB and COX-2 were upregulated by PpIX-PDT but significantly attenuated when in combination with BGP extract. BGP extract was also found to significantly enhance the intracellular accumulation of PpIX in A431 cells. BGP extract increased PpIX-mediated photocytotoxicity in a xenograft model as well. Our findings provide evidence for a synergistic effect of BGP extract in PpIX-PDT both in vitro and in vivo.

Multi-stimuli responsive block copolymers as a smart release platform for a polypyridyl ruthenium complex

An efficient protocol for the preparation of poly(N,N-dimethylaminoethyl methacrylate)(PDMAEMA)-based multi-stimuli responsive block copolymers (BCPs) with poly(methyl methacrylate) (PMMA)viaanionic polymerization protocols is presented.