Aminolevulinic Acid (ALA) as a Prodrug in Photodynamic Therapy of Cancer

The abscopal effects of sonodynamic therapy in cancer

The abscopal effect is a phenomenon wherein localised therapy on the primary tumour leads to regression of distal metastatic growths. Interestingly, various pre-clinical studies utilising sonodynamic therapy (SDT) have reported significant abscopal effects, however, the mechanism remains largely enigmatic. SDT is an emerging non-invasive cancer treatment that uses focussed ultrasound (FUS) and a sonosensitiser to induce tumour cell death. To expand our understanding of abscopal effects of SDT, we have summarised the preclinical studies that have found SDT-induced abscopal responses across various cancer models, using diverse combination strategies with nanomaterials, microbubbles, chemotherapy, and immune checkpoint inhibitors. Additionally, we shed light on the molecular and immunological mechanisms underpinning SDT-induced primary and metastatic tumour cell death, as well as the role and efficacy of different sonosensitisers. Notably, the observed abscopal effects underscore the need for continued investigation into the SDT-induced 'vaccine-effect' as a potential strategy for enhancing systemic anti-tumour immunity and combating metastatic disease. The results of the first SDT human clinical trials are much awaited and are hoped to enable the further evaluation of the safety and efficacy of SDT, paving the way for future studies specifically designed to explore the potential of translating SDT-induced abscopal effects into clinical reality.

Demystifying the management of cancer through smart nano-biomedicine via regulation of reactive oxygen species

Advancements in therapeutic strategies and combinatorial approaches for cancer management have led to the majority of cancers in the initial stages to be regarded as treatable and curable. However, certain high-grade cancers in the initial stages are still regarded as chronic and difficult to manage, requiring novel therapeutic strategies. In this era of targeted and precision therapy, novel strategies for targeted delivery of drug and synergistic therapies, integrating nanotherapeutics, polymeric materials, and modulation of the tumor microenvironment are being developed. One such strategy is the study and utilization of smart-nano biomedicine, which refers to stimuli-responsive polymeric materials integrated with the anti-cancer drug that can modulate the reactive oxygen species (ROS) in the tumor microenvironment or can be ROS responsive for the mitigation as well as management of various cancers. The article explores in detail the ROS, its types, and sources; the antioxidant system, including scavengers and their role in cancer; the ROS-responsive targeted polymeric materials, including synergistic therapies for the treatment of cancer via modulating the ROS in the tumor microenvironment, involving therapeutic strategies promoting cancer cell death; and the current landscape and future prospects.

Efficacy of photodynamic therapy using 5-aminolevulinic acid-induced photosensitization is enhanced in pancreatic cancer cells with acquired drug resistance

The use of 5-aminolevulinic acid (ALA) as a precursor for protoporphyrin IX (PpIX) is an established photosensitization strategy for photodynamic therapy (PDT) and fluorescence guided surgery. Ongoing studies are focused on identifying approaches to enhance PpIX accumulation as well as to identify tumor sub-types associated with high PpIX accumulation. In this study, we investigated PpIX accumulation and PDT treatment response with respect to nodule size in 3D cultures of pancreatic cancer cells (Panc1) and a derivative subline (Panc1OR), which has acquired drug resistance and exhibits increased epithelial mesenchymal transition. In monolayer and 3D culture dose response studies the Panc1OR cells exhibit significantly a higher level of photokilling at lower light doses than the drug naïve cells. Panc1OR also exhibits increased PpIX accumulation. Further analysis of cell killing efficiency per molecule of intracellular PpIX indicates that the drug resistant cells are intrinsically more responsive to PDT. Additional investigation using exogenous delivery of PpIX also shows higher cell killing in drug resistant cells, under conditions which achieve approximately the same intracellular PpIX. Overall these results are significant as they demonstrate that this example of drug-resistant cells associated with aggressive disease progression and poor clinical outcomes, show increased sensitivity to ALA-PDT.

Enhancing Phototoxicity in BODIPY-Perylene Charge Transfer Dyads by Combined Iodination and Mesylation

The uptake and phototoxicity of a family of BODIPY-perylene charge transfer dyads are compared in live cancer and non-cancer cell lines to evaluate their performance in imaging and photodynamic therapy (PDT). The impact of iodination and mesylation of the meso position of the compounds on their optical properties, cell uptake and toxicity are compared. Notably, across all derivatives the probes were minimally dark toxic up to 50 μM, (the maximum concentration tested), but exhibited outstanding phototoxicity with nanomolar IC50 values and impressive phototoxic indices (PI, ratio of dark IC50 to light IC50), with best performance for the mesylated iodinated derivative MB2PI, which had a PI of >218 and >8.9 in MCF-7 cells and tumour spheroids respectively. This is significantly higher than non-iodinated analogue MB2P in MCF-7 cells with an observed PI of >109 and slightly higher than MB2PI in spheroids with a PI of >8. This compound also showed interesting emission spectral variation with localisation that responded to stimulation of inflammation. Additional studies confirmed efficient singlet oxygen generation by the BODIPYs, suggesting a Type II mechanism of phototoxicity. Overall, the data indicates that combining charge transfer and iodination is an effective strategy for enhancing phototherapeutic capacity of BODIPY PS.

Photodynamic Therapy: A Novel Approach for Head and Neck Cancer Treatment with Focusing on Oral Cavity

Oral cancers, specifically oral squamous cell carcinoma (OSCC), pose a significant global health challenge, with high incidence and mortality rates. Conventional treatments such as surgery, radiotherapy, and chemotherapy have limited effectiveness and can result in adverse reactions. However, as an alternative, photodynamic therapy (PDT) has emerged as a promising option for treating oral cancers. PDT involves using photosensitizing agents in conjunction with specific light to target and destroy cancer cells selectively. The photosensitizers accumulate in the cancer cells and generate reactive oxygen species (ROS) upon exposure to the activating light, leading to cellular damage and ultimately cell death. PDT offers several advantages, including its non-invasive nature, absence of known long-term side effects when administered correctly, and cost-effectiveness. It can be employed as a primary treatment for early-stage oral cancers or in combination with other therapies for more advanced cases. Nonetheless, it is important to note that PDT is most effective for superficial or localized cancers and may not be suitable for larger or deeply infiltrating tumors. Light sensitivity and temporary side effects may occur but can be managed with appropriate care. Ongoing research endeavors aim to expand the applications of PDT and develop novel photosensitizers to further enhance its efficacy in oral cancer treatment. This review aims to evaluate the effectiveness of PDT in treating oral cancers by analyzing a combination of preclinical and clinical studies.

Secondary hyperparathyroidism in chronic kidney disease: pathophysiology, current treatments and investigational drugs

INTRODUCTION

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD). It begins as an adaptive increase in parathyroid hormone levels to prevent calcium and phosphate derangements. Over time, this condition becomes maladaptive and is associated with increased morbidity and mortality. Current therapies encompass phosphate-lowering strategies, vitamin D analogues, calcimimetics and parathyroidectomy. These approaches harbor inherent limitations, stimulating interest in the development of new drugs for SHPT to overcome these limitations and improve survival and quality of life among CKD patients.

AREAS COVERED

This review delves into the main pathophysiological mechanisms involved in SHPT, alongside the treatment options that are currently available and under active investigation. Data presented herein stem from a comprehensive search conducted across PubMed, Web of Science, ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) spanning from 2000 onwards.

EXPERT OPINION

The advancements in investigational drugs for SHPT hold significant promise for enhancing treatment efficacy while minimizing side effects associated with conventional therapies. Although several challenges still hinder their adoption in clinical practice, ongoing research will likely continue to expand the available therapeutic options, refine treatment strategies, and tailor them to individual patient profiles.

A novel chlorin derivative Shengtaibufen (STBF) mediated photodynamic therapy combined with iodophor for the treatment of chronic superficial leg wounds infected with methicillin-resistant Staphylococcus aureus: A retrospective clinical study

OBJECTIVE

Chronic wounds are costly and difficult to treat, resulting in morbidity and even mortality in some cases due to a high methicillin-resistant Staphylococcus aureus (MRSA) burden contributing to chronicity. We aimed to observe the antimicrobial activity and healing-promoting effect of a novel photosensitizer Shengtaibufen (STBF)-mediated antibacterial photodynamic therapy (PDT) on MRSA-infected chronic leg ulcers.

PATIENTS AND METHODS

This was a retrospective, comparative, single-center clinical study. A total of 32 patients with chronic lower limb wounds infected with MRSA from January 2022 to December 2023 were finally included in this study by searching the electronic medical records of the dermatology department of Huadong Hospital, including a group of red light combined with iodophor (control+iodophor, n=16, receiving red light once a week for 8 weeks and routine dressing change with iodophor once a day) and a group of STBF-mediated PDT (STBF-PDT) combined with iodophor (STBF-PDT+iodophor, n=16, receiving STBF-PDT and routine dressing change with iodophor once a day). STBF-PDT was performed once a week (1 mg/ml STBF, 1 h incubation, 630 nm red light, 80 J/cm2) for 8 weeks. The primary endpoints included wound clinical signs, wound size, wound-related pain, re-epithelialization score, MRSA load and wound-related quality of life (wound-QoL). Any adverse events were also recorded.

RESULTS

We found that STBF-PDT+iodophor could effectively alleviate clinical infection symptoms, accelerate wound closure, reduce average biological burden and improve wound-QoL without severe adverse events in comparison to the control+iodophor group. The STBF-PDT+iodophor group obtained a mean percentage reduction of 65.22% in wound size (from 18.96±11.18 cm2 to 6.59±7.94 cm2) and excellent re-epithelialization scores, as compared with a decrease of 30.17% (from 19.23±9.80 cm2 to 13.43±9.32 cm2) for the control+iodophor group. Significant differences in wound area were observed at week 6 (p=0.028*) and week 8 (p=0.002**). The bacterial load decreased by 99.86% (from 6.45 × 107±2.69 × 107 to 8.94 × 104±1.92 × 105 CFU/cm2, p<0.0001) in the STBF-PDT+iodophor group and 1.82% (from 6.61 × 107±2.13 × 107 to 6.49 × 107±2.01 × 107 CFU/cm2, p=0.029) in the control+iodophor group. The wound-QoL in STBF-PDT+iodophor group had a 51.62% decrease in overall score (from 29.65±9.33 at the initial to 14.34±5.17 at week 8, p<0.0001) compared to those receiving red light and routine wound care (from 30.73±17.16 to 29.32±15.89 at week 8, p=0.003). Moreover, patients undergoing STBF-PDT+iodophor exhibited great improvements in all domains of wound-QoL (physical, psychological and everyday-life), whereas the control+iodophor group ameliorated in only one field (everyday-life).

CONCLUSION

Our data confirmed that a novel photosensitizer, STBF-mediated PDT, when combined with iodophor, served as a potential modality for MRSA infection and a possible therapy for other drug-resistant microorganisms, and as a promising alternative for chronic cutaneous infectious diseases.

Hemin enhances the 5-aminolevulinic acid-photodynamic therapy effect through the changes of cellular iron homeostasis

BACKGROUND

Photodynamic therapy (PDT) has been utilized as a promising alternative cancer treatment due to its minimum invasiveness over the years. Exogenous 5-aminolevulinic acid (ALA) triggers protoporphyrin IX (PpIX) accumulation, which happens in cancer cells. However, certain types of cancer exhibit reduced effectiveness in the PpIX accumulation mechanism. This study aimed to determine the effect of ALA-PDT combination with hemin on gastric carcinoma TMK-1 cells.

METHODS

This study utilized TMK-1 gastric cancer cell line to evaluate PpIX, ROS, and Fe2+ accumulation following the administration of ALA, hemin, and a combination of ALA and hemin PDT. We also evaluate the mRNA expressions related to iron homeostasis and treatment impacts on cell viability.

RESULTS

The co-addition of ALA and hemin PDT for 4 h of treatment resulted in a significant decrease in cell viability by up to 18 %. While ALA-PDT enhanced PpIX metabolism, the addition of hemin influenced both the production of reactive oxygen species (ROS) and cellular iron homeostasis by inducing Fe2+ accumulation and affecting mRNA levels of IRP, Tfr1, Ferritin, NFS1, and SDHB.

CONCLUSION

These findings suggest that the addition of ALA and hemin enhances phototoxicity in TMK-1 cells. The combination of ALA and hemin with PDT induces cell death, evidenced by increased cytotoxicity properties such as PpIX and ROS, along with significant changes in TMK-1 gastric cancer iron homeostasis. Therefore, the combination of ALA and hemin could be one of the alternatives in photodynamic therapy for cancer in the future.

Photodynamic Therapeutic Effect during 5-Aminolevulinic Acid-Mediated Photodynamic Diagnosis-Assisted Transurethral Resection of Bladder Tumors

Background

Photodynamic diagnosis-assisted transurethral resection of bladder tumors (PDD-TURBT) enhances detection of elusive lesions compared to standard white light-transurethral resection of bladder tumors (WL-TURBT). If minimal light exposure during PDD-TURBT induces the accumulation of reactive oxygen species (ROS), potentially resulting in phototoxicity in small lesions, apoptosis may be triggered in residual small tumors, allowing them to escape resection. We investigated the hypothesis of a potential photodynamic therapeutic effect during PDD-TURBT.

Methods and Materials

Our study, conducted between January 2016 and December 2020 at Nara Medical University Hospital, focused on a specific emphasis on ROS production. Immunohistochemical analysis for thymidine glycol and N ε -hexanoyl-lysine was performed on 69 patients who underwent 5-aminolevulinic acid-mediated PDD-TURBT and 28 patients who underwent WL-TURBT. Additionally, we incrementally applied the minimal irradiation energy to T24 and UM-UC-3 cells treated with 5-aminolevulinic acid using instruments similar to those used in PDD-TURBT and evaluated intracellular ROS production and phototoxicity.

Results

Immunohistochemical analysis revealed a significant increase in production of thymidine glycol and N ε -hexanoyl-lysine within the PDD-TURBT group. In T24 and UM-UC-3 cells treated with 5-aminolevulinic acid and light exposure, immunofluorescent staining demonstrated a dose-dependent increase in intracellular ROS production. In addition, higher irradiation energy levels were associated with a greater increase in ROS production and phototoxicity, as well as more significant decrease in mitochondrial membrane potential.

Conclusion

Although the irradiation energy used in PDD-TURBT did not reach the levels commonly used in photodynamic therapy, our findings support the presence of a potential cytotoxic effect on bladder lesions during PDD-TURBT.

Fluorescence in neurosurgery: its therapeutic and diagnostic significance - a comprehensive review

This review provides a comprehensive overview of the therapeutic and diagnostic implications of fluorescence imaging in neurosurgery. Fluorescence imaging has become a valuable intraoperative visualization and guidance tool, facilitating precise surgical interventions. The therapeutic role of fluorescence is examined, including its application in photodynamic therapy and tumor-targeted therapy. It also explores its diagnostic capabilities in tumor detection, margin assessment, and blood-brain barrier evaluation. Drawing from clinical and preclinical studies, the review underscores the growing evidence supporting the efficacy of fluorescence imaging in neurosurgical practice. Furthermore, it discusses current limitations and future directions, emphasizing the potential for emerging technologies to enhance the utility and accessibility of fluorescence imaging, ultimately improving patient outcomes in neurosurgery.

Description of mitochondrial oxygen tension and its variability in healthy volunteers

OBJECTIVES

Describing mitochondrial oxygenation (mitoPO2) and its within- and between-subject variability over time after 5-aminolevulinic acid (ALA) plaster application in healthy volunteers.

DESIGN

Prospective cohort study.

SETTING

Measurements were performed in Leiden University Medical Center, the Netherlands.

PARTICIPANTS

Healthy volunteers enrolled from July to September 2020.

INTERVENTIONS

Two ALA plasters were placed parasternal left and right, with a 3-hour time interval, to examine the influence of the calendar time on the value of mitoPO2. We measured mitoPO2 at 4, 5, 7, 10, 28, and 31 hours after ALA plaster 1 application, and at 4, 5, 7, 25, and 28 hours after ALA plaster 2 application.

PRIMARY AND SECONDARY OUTCOME MEASURES

At each time point, five mitoPO2 measurements were performed. Within-subject variability was defined as the standard deviation (SD) of the mean of five measurements per timepoint of a study participant. The between-subject variability was the SD of the mean mitoPO2 value of the study population per timepoint.

RESULTS

In 16 completed inclusions, median mitoPO2 values and within-subject variability were relatively similar over time at all time points for both plasters. An increase in overall between-subject variability was seen after 25 hours ALA plaster time (19.6 mm Hg vs 23.9 mm Hg after respectively 10 and 25 hours ALA plaster time).

CONCLUSIONS

The mitoPO2 values and within-subject variability remained relatively stable over time in healthy volunteers. An increase in between-subject variability was seen after 25 hours ALA plaster time warranting replacement of the ALA plaster one day after its application.

TRIAL REGISTRATION

ClinicalTrials.gov with trial number NCT04626661.

The eEF1A protein in cancer: Clinical significance, oncogenic mechanisms, and targeted therapeutic strategies

Eukaryotic elongation factor 1A (eEF1A) is among the most abundant proteins in eukaryotic cells. Evolutionarily conserved across species, eEF1A is in charge of translation elongation for protein biosynthesis as well as a plethora of non-translational moonlighting functions for cellular homeostasis. In malignant cells, however, eEF1A becomes a pleiotropic driver of cancer progression via a broad diversity of pathways, which are not limited to hyperactive translational output. In the past decades, mounting studies have demonstrated the causal link between eEF1A and carcinogenesis, gaining deeper insights into its multifaceted mechanisms and corroborating its value as a prognostic marker in various cancers. On the other hand, an increasing number of natural and synthetic compounds were discovered as anticancer eEF1A-targeting inhibitors. Among them, plitidepsin was approved for the treatment of multiple myeloma whereas metarrestin was currently under clinical development. Despite significant achievements in these two interrelated fields, hitherto there lacks a systematic examination of the eEF1A protein in the context of cancer research. Therefore, the present work aims to delineate its clinical implications, molecular oncogenic mechanisms, and targeted therapeutic strategies as reflected in the ever expanding body of literature, so as to deepen mechanistic understanding of eEF1A-involved tumorigenesis and inspire the development of eEF1A-targeted chemotherapeutics and biologics.

5-ALA localises to the autophagy compartment and increases its fluorescence upon autophagy enhancement through caloric restriction and spermidine treatment in human glioblastoma

Glioblastoma Multiforme (GBM) is the most invasive and prevalent Central Nervous System (CNS) malignancy. It is characterised by diffuse infiltrative growth and metabolic dysregulation that impairs the extent of surgical resection (EoR), contributing to its poor prognosis. 5-Aminolevulinic acid (5-ALA) fluorescence-guided surgical resection (FGR) takes advantage of the preferential generation of 5-ALA-derived fluorescence signal in glioma cells, thereby improving visualisation and enhancing the EoR. However, despite 5-ALA FGR is a widely used technique in the surgical management of malignant gliomas, the infiltrative tumour margins usually show only vague or no visible fluorescence and thus a significant amount of residual tumour tissue may hence remain in the resection cavity, subsequently driving tumour recurrence. To investigate the molecular mechanisms that govern the preferential accumulation of 5-ALA in glioma cells, we investigated the precise subcellular localisation of 5-ALA signal using Correlative Light and Electron Microscopy (CLEM) and colocalisation analyses in U118MG glioma cells. Our results revealed strong 5-ALA signal localisation in the autophagy compartment - specifically autolysosomes and lysosomes. Flow cytometry was employed to investigate whether autophagy enhancement through spermidine treatment (SPD) or nutrient deprivation/caloric restriction (CR) would enhance 5-ALA fluorescence signal generation. Indeed, SPD, CR and a combination of SPD/CR treatment significantly increased 5-ALA signal intensity, with a most robust increase in signal intensity observed in the combination treatment of SPD/CR. When using 3-D glioma spheroids to assess the effect of 5-ALA on cellular ultrastructure, we demonstrate that 5-ALA exposure leads to cytoplasmic disruption, vacuolarisation and large-scale mitophagy induction. These findings not only suggest a critical role for the autophagy compartment in 5-ALA engagement and signal generation but also point towards a novel and practically feasible approach to enhance 5-ALA fluorescence signal intensity. The findings may highlight that indeed autophagy control may serve as a promising avenue to promote an improved resection and GBM prognosis.

Current Photodynamic Therapy for Glioma Treatment: An Update

Research on the development of photodynamic therapy for the treatment of brain tumors has shown promise in the treatment of this highly aggressive form of brain cancer. Analysis of both in vivo studies and clinical studies shows that photodynamic therapy can provide significant benefits, such as an improved median rate of survival. The use of photodynamic therapy is characterized by relatively few side effects, which is a significant advantage compared to conventional treatment methods such as often-used brain tumor surgery, advanced radiotherapy, and classic chemotherapy. Continued research in this area could bring significant advances, influencing future standards of treatment for this difficult and deadly disease.

Modifications of DAMPs levels in extracellular environment induced by aminolevulinic acid-based photodynamic therapy of esophageal cancer cells

PURPOSE

Immunogenic cell death plays an important role in anticancer treatment because it combines cell death with appearance of damage associated molecular patterns that have the potential to activate anticancer immunity. Effects of damage associated molecular patterns induced by aminolevulinic acid-based photodynamic therapy were studied mainly on dendritic cells. They have not been deeply studied on macrophages that constitute the essential component of the tumor microenvironment. The aim of this study was to analyze features of esophageal cancer cell death in relation to release capacity of damage associated molecular pattern species, and to test the effect of related extracellular environmental alterations on macrophages.

MATERIAL AND METHODS

Esophageal Kyse 450 carcinoma cells were subjected to aminolevulinic acid-based photodynamic therapy at different concentrations of aminolevulinic acid. Resting, IFN/LPS and IL-4 macrophage subtypes were prepared from monocytic THP-1 cell line. Cell death features and macrophage modifications were analyzed by fluorescence-based live cell imaging. ATP and HMGB1 levels in cell culture media were determined by ELISA assays. The presence of lipid peroxidation products in culture media was assessed by spectrophotometric detection of thiobarbituric acid reactive substances.

RESULTS

Aminolevulinic acid-based photodynamic therapy induced various death pathways in Kyse 450 cells that included features of apoptosis, necrosis and ferroptosis. ATP amounts in extracellular environment of treated Kyse 450 cells increased with increasing aminolevulinic acid concentration. Levels of HMGB1, detectable by ELISA assay in culture media, were decreased after the treatment. Aminolevulinic acid-based photodynamic therapy induced lipid peroxidation of cellular structures and increased levels of extracellular lipid peroxidation products. Incubation of resting and IL-4 macrophages in conditioned medium from Kyse 450 cells treated by aminolevulinic acid-based photodynamic therapy induced morphological changes in macrophages, however, comparable alterations were induced also by conditioned medium from untreated cancer cells.

CONCLUSION

Aminolevulinic acid-based photodynamic therapy leads to alterations in local extracellular levels of damage associated molecular patterns, however, comprehensive studies are needed to find whether they can be responsible for macrophage phenotype modifications.

In vitro evaluation of the efficacy of photodynamic therapy using 5-ALA on homologous feline mammary tumors in 2D and 3D culture conditions and a mouse subcutaneous model with 3D cultured cells

BACKGROUND

Numerous studies have shown that photodynamic therapy (PDT) has a therapeutic effect on mammary tumor cells, with 5-aminolevulinic acid (5-ALA-HCL) being a commonly used photosensitizer for PDT. Feline mammary tumors (FMTs) are relatively common. However, the cytotoxic and antitumor effects of 5-ALA-PDT on FMTs have not been clarified. To this end, we evaluated the therapeutic effect of 5-ALA-PDT on FMTs through in vitro experiments using an FMT FKR cell line established for this study.

METHODS

We performed 5-ALA-PDT in 2D-cultured FKR-A (adherent cells) and 3D-cultured FKR-S (spheroid cells) cells and performed a series of studies to evaluate the cell viability and determine the protoporphyrin IX (PpIX) content in the cells as well as the expression levels of mRNAs associated with PpIX production and release. An in vivo study was performed to assess the effectiveness of 5-ALA-PDT.

RESULTS

There was a significant difference in the concentration of PpIX in FMT cells under different incubation culture modes (2D versus 3D culture). The concentration of PpIX in FMT cells was correlated with the differences in cell culture (2D and 3D) as well as the expression levels of genes such as PEPT1, PEPT2, FECH, and HO-1.

CONCLUSIONS

In the in vitro study, 5-ALA-PDT had a stronger inhibitory effect on 3D-cultured FKR-S cells, which resemble the internal environment of organisms more closely. We also observed a significant inhibitory effect of 5-ALA-PDT on FMT cells in vivo. To our knowledge, this is the first study on 5-ALA-PDT for FMTs under both 2D and 3D conditions.

What Is the Impact of Antimicrobial Photodynamic Therapy on Oral Candidiasis? An In Vitro Study

This study aimed to evaluate the ability of photodynamic therapy, based on the use of a gel containing 5% delta aminolaevulinic acid (ALAD) for 45' followed by irradiation with 630 nm LED (PDT) for 7', to eradicate Candida albicans strains without damaging the gingiva. C. albicans oral strains and gingival fibroblasts (hGFs) were used to achieve these goals. The potential antifungal effects on a clinical resistant C. albicans S5 strain were evaluated in terms of biofilm biomass, colony forming units (CFU/mL) count, cell viability by live/dead analysis, and fluidity membrane changes. Concerning the hGFs, viability assays, morphological analysis (optical, scanning electronic (SEM), and confocal laser scanning (CLSM) microscopes), and assays for reactive oxygen species (ROS) and collagen production were performed. ALAD-mediated aPDT (ALAD-aPDT) treatment showed significant anti-biofilm activity against C. albicans S5, as confirmed by a reduction in both the biofilm biomass and CFUs/mL. The cell viability was strongly affected by the treatment, while on the contrary, the fluidity of the membrane remained unchanged. The results for the hGFs showed an absence of cytotoxicity and no morphological differences in cells subjected to ALAD-aPDT expected for CLSM results that exhibited an increase in the thickening of actin filaments. ROS production was augmented only at 0 h and 3 h, while the collagen appeared enhanced 7 days after the treatment.

Optimizing the administrated light dose during 5-ALA-mediated photodynamic therapy: Murine 4T1 breast cancer model

Photodynamic therapy (PDT) is already used to treat many cancers, including breast cancer, the most common cancer in women worldwide. The destruction basis of this method is on produced singlet oxygen which is extremely reactive and is a major agent of tumor cell killing. The measurement of singlet oxygen produced within PDT is essential in predicting treatment outcomes and their optimization. This study aims to determine the optimal total light dose administered during PDT by calculating the singlet oxygen to facilitate the prediction of the treatment outcome in mice bearing 4T1 cell breast cancer. Monitoring the changes in photosensitizer fluorescence signals during PDT due to photobleaching can be one of the methods of determination of singlet oxygen generation in the PDT process. This study determined the oxygen singlet as a photodynamic dose from the three-dimensional Monte Carlo method and the photobleaching empirical dose constant. The photobleaching dose constant was established non-invasively by monitoring the in vivo protoporphyrin IX (PpIX) fluorescence and photobleaching during PDT. The photobleaching dose constant (β) in J/cm2 was calculated using empirical fluorescence data. The in vivo photobleaching dose constant of aminolevulinic acid was found to be 11.6 J/cm2 and based on this value, the optimal treatment light dose was estimated at 120 J/cm2 in mice bearing 4T1 breast cancer. It is concluded that information can be obtained regarding optimal treatment parameters by monitoring the in vivo PpIX fluorescence and photobleaching during PDT.

Photodynamic Therapy in Treating a Subset of Basal Cell Carcinoma: Strengths, Shortcomings, Comparisons with Surgical Modalities, and Potential Role as Adjunctive Therapy

Basal cell carcinoma (BCC) is the most common skin cancer, for which there are multiple treatment options, including the gold standard Mohs micrographic surgery (MMS), surgical excision, electrodesiccation and curettage, radiation therapy, cryosurgery, and photodynamic therapy (PDT). While PDT is currently approved for treating actinic keratosis, it has been used off-label to treat BCC patients who may not tolerate surgery or other treatment modalities. We present a review of the efficacy of these modalities and describe important considerations that affect the usage of PDT and MMS. ALA-PDT and MAL-PDT are both efficacious treatment options for lower-risk BCC that can serve as non-invasive alternatives to surgical excision with favorable cosmetic outcomes in patients unsuitable to undergo surgery. In particular, PDT may be considered an adjuvant for the prevention and treatment of BCC lesions in patients with some genetic syndromes such as Gorlin syndrome, and in combination with surgical excision in lesions presenting in certain locations. Limitations to PDT include lack of margin control to prevent recurrence, pain, and cost of certain photosensitizers. Future studies should investigate the role of PDT as adjunctive therapy, standardization of protocols, and causes and ways to address recurrence following PDT treatment.

Multimodal OCT Control for Early Histological Signs of Vulvar Lichen Sclerosus Recurrence after Systemic PDT: Pilot Study

Photodynamic therapy (PDT) is a modern treatment for severe or treatment-resistant vulvar lichen sclerosus (VLS). The chronic and recurrent nature of VLS requires control of recurrences at an early stage. In this paper, a non-invasive multimodal optical coherence tomography (OCT) method was used to control for early histological signs of VLS recurrence after systemic PDT using Photodithazine®. To interpret the OCT data, a histological examination was performed before PDT and 3 months after PDT. Two groups of patients were identified: with early histological signs of VLS recurrence (Group I, n = 5) and without histological signs of VLS recurrence (Group II, n = 6). We use structural OCT, OCT angiography, and OCT lymphangiography throughout 6 months after PDT to visually assess the skin components and to quantitatively assess the dermis by calculating the depth-resolved attenuation coefficient and the density of blood and lymphatic vessels. The OCT data assessment showed a statistically significant difference between the patient groups 3 months after PDT. In Group II, all the studied OCT parameters reached maximum values by the 3rd month after PDT, which indicated recovery of the skin structure. At the same time, in Group I, the values of OCT parameters did not approach the values those in Group II even after 6 months. The obtained results of multimodal OCT can be used for non-invasive control of early histological recurrence of VLS after systemic PDT and for adjusting treatment tactics in advance, without waiting for new clinical manifestations of the disease.

Beyond traditional therapy: Mucoadhesive polymers as a new frontier in oral cancer management

In recent times mucoadhesive drug delivery systems are gaining popularity in oral cancer. It is a malignancy with high global prevalence. Despite significant advances in cancer therapeutics, improving the prognosis of late-stage oral cancer remains challenging. Targeted therapy using mucoadhesive polymers can improve oral cancer patients' overall outcome by offering enhanced oral mucosa bioavailability, better drug distribution and tissue targeting, and minimizing systemic side effects. Mucoadhesive polymers can also be delivered via different formulations such as tablets, films, patches, gels, and nanoparticles. These polymers can deliver an array of medicines, making them an adaptable drug delivery approach. Drug delivery techniques based on these mucoadhesive polymers are gaining traction and have immense potential as a prospective treatment for late-stage oral cancer. This review examines leading research in mucoadhesive polymers and discusses their potential applications in treating oral cancer.

The in vitro anti-cancer synergy of neurokinin-1 receptor antagonist, aprepitant, and 5-aminolevulinic acid in glioblastoma

Glioblastoma multiforme (GBM) is the most malignant type of cerebral neoplasm in adults with a poor prognosis. Currently, combination therapy with different anti-cancer agents is at the forefront of GBM research. Hence, this study aims to evaluate the potential anti-cancer synergy of a clinically approved neurokinin-1 receptor antagonist, aprepitant, and 5-aminolevulinic acid (5-ALA), a prodrug that elicits fluorescent porphyrins in gliomas on U-87 human GBM cells. We found that aprepitant and 5-ALA effectively inhibited GBM cell viability. The combinatorial treatment of these drugs exerted potent synergistic growth inhibitory effects on GBM cells. Moreover, aprepitant and 5-ALA induced apoptosis and altered the levels of apoptotic genes (up-regulation of Bax and P53 along with downregulation of Bcl-2). Furthermore, aprepitant and 5-ALA increased the accumulation of protoporphyrin IX, a highly pro-apoptotic and fluorescent photosensitizer. Aprepitant and 5-ALA significantly inhibited GBM cell migration and reduced matrix metalloproteinases (MMP-2 and MMP-9) activities. Importantly, all these effects were more prominent following aprepitant-5-ALA combination treatment than either drug alone. Collectively, the combination of aprepitant and 5-ALA leads to considerable synergistic anti-proliferative, pro-apoptotic, and anti-migratory effects on GBM cells and provides a firm basis for further evaluation of this combination as a novel therapeutic approach for GBM.

Photodynamic Therapy for Glioblastoma: Illuminating the Path toward Clinical Applicability

Glioblastoma (GBM) is the most common adult brain cancer. Despite extensive treatment protocols comprised of maximal surgical resection and adjuvant chemo-radiation, all glioblastomas recur and are eventually fatal. Emerging as a novel investigation for GBM treatment, photodynamic therapy (PDT) is a light-based modality that offers spatially and temporally specific delivery of anti-cancer therapy with limited systemic toxicity, making it an attractive option to target GBM cells remaining beyond the margins of surgical resection. Prior PDT approaches in GBM have been predominantly based on 5-aminolevulinic acid (5-ALA), a systemically administered drug that is metabolized only in cancer cells, prompting the release of reactive oxygen species (ROS), inducing tumor cell death via apoptosis. Hence, this review sets out to provide an overview of current PDT strategies, specifically addressing both the potential and shortcomings of 5-ALA as the most implemented photosensitizer. Subsequently, the challenges that impede the clinical translation of PDT are thoroughly analyzed, considering relevant gaps in the current PDT literature, such as variable uptake of 5-ALA by tumor cells, insufficient tissue penetrance of visible light, and poor oxygen recovery in 5-ALA-based PDT. Finally, novel investigations with the potential to improve the clinical applicability of PDT are highlighted, including longitudinal PDT delivery, photoimmunotherapy, nanoparticle-linked photosensitizers, and near-infrared radiation. The review concludes with commentary on clinical trials currently furthering the field of PDT for GBM. Ultimately, through addressing barriers to clinical translation of PDT and proposing solutions, this review provides a path for optimizing PDT as a paradigm-shifting treatment for GBM.

ALA/Ag2S/MnO2 Hybrid Nanoparticles for Near-Infrared Image-Guided Long-Wavelength Phototherapy of Breast Cancer

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) based on temperature increase and the formation of reactive oxygen species (ROS), respectively, is an exciting avenue to provide local and improved therapy of tumors with minimal off-site toxicity. 5-Aminolevulinic acid (ALA) is one of the most popular PDT pro-drugs, and its efficiency improves significantly when delivered to tumors with nanoparticles (NPs). But the tumor site's hypoxic environment is a handicap for the oxygen-consuming PDT process. In this work, highly stable, small, theranostic NPs composed of Ag₂S quantum dots and MnO₂, electrostatically loaded with ALA, were developed for enhanced PDT/PTT combination of tumors. MnO₂ catalyzes endogenous H₂O₂ to O₂ conversion and glutathione depletion, enhancing ROS generation and ALA-PDT efficiency. Ag₂S quantum dots (AS QDs) conjugated with bovine serum albumin (BSA) support MnO₂ formation and stabilization around Ag₂S. AS-BSA-MnO₂ provided a strong intracellular near-infrared (NIR) signal and increased the solution temperature by 15 °C upon laser irradiation at 808 nm (215 mW, 10 mg/mL), proving the hybrid NP as an optically trackable, long-wavelength PTT agent. In the in vitro studies, no significant cytotoxicity was observed in the absence of laser irradiation in healthy (C2C12) or breast cancer cell lines (SKBR3 and MDA-MB-231). The most effective phototoxicity was observed when AS-BSA-MnO₂-ALA-treated cells were co-irradiated for 5 min with 640 nm (300 mW) and 808 nm (700 mW) due to enhanced ALA-PDT combined with PTT. The viability of cancer cells decreased to approximately 5-10% at 50 μg/mL [Ag], corresponding to 1.6 mM [ALA], whereas at the same concentration, individual PTT and PDT treatments decreased the viability to 55-35%, respectively. The late apoptotic death of the treated cells was mostly correlated with high ROS levels and lactate dehydrogenase. Overall, these hybrid NPs overcome tumor hypoxia, deliver ALA to tumor cells, and provide both NIR tracking and enhanced PDT + PTT combination therapy upon short, low-dose co-irradiation at long wavelengths. These agents that may be utilized for treating other cancer types are also highly suitable for in vivo investigations.

Reactive Oxygen Species Produced by 5-Aminolevulinic Acid Photodynamic Therapy in the Treatment of Cancer

Cancer is the leading cause of death worldwide and several anticancer therapies take advantage of the ability of reactive oxygen species to kill cancer cells. Added to this is the ancient hypothesis that light alone can be used to kill cancer cells. 5-aminolevulinic acid-photodynamic therapy (5-ALA-PDT) is a therapeutic option for a variety of cutaneous and internal malignancies. PDT uses a photosensitizer that, activated by light in the presence of molecule oxygen, forms ROS, which are responsible for the apoptotic activity of the malignant tissues. 5-ALA is usually used as an endogenous pro-photosensitizer because it is converted to Protoporphyrin IX (PpIX), which enters into the process of heme synthesis and contextually becomes a photosensitizer, radiating a red fluorescent light. In cancer cells, the lack of the ferrochelatase enzyme leads to an accumulation of PpIX and consequently to an increased production of ROS. PDT has the benefit of being administered before or after chemotherapy, radiation, or surgery, without impairing the efficacy of these treatment techniques. Furthermore, sensitivity to PDT is unaffected by the negative effects of chemotherapy or radiation. This review focuses on the studies done so far on 5-ALA-PDT and its efficacy in the treatment of various cancer pathologies.

Suppression of angiotensin converting enzyme 2, a host receptor for SARS-CoV-2 infection, using 5-aminolevulinic acid in vitro

Angiotensin converting enzyme 2 (ACE2), an entry receptor found on the surface of host cells, is believed to be detrimental to the infectious capability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Scientists have been working on finding a cure since its outbreak with limited success. In this study, we evaluated the potential of 5-aminolevulinic acid hydrochloride (ALA) in suppressing ACE2 expression of host cells. ACE2 expression and the production of intracellular porphyrins following ALA administration were carried out. We observed the reduction of ACE2 expression and intracellular porphyrins following ALA administration. ALA suppressed the ACE2 expression in host cells which might prevent binding of SARS-CoV-2 to host cells. Co-administration of ALA and sodium ferrous citrate (SFC) resulted in a further decrease in ACE2 expression and increase in intracellular heme level. This suggests that the suppression of ACE2 expression by ALA might occur through heme production. We found that the inhibition of heme oxygenase-1 (HO-1), which is involved in heme degradation, also resulted in decrease in ACE2 expression, suggesting a potential role of HO-1 in suppressing ACE2 as well. In conclusion, we speculate that ALA, together with SFC administration, might serve as a potential therapeutic approach in reducing SARS-CoV-2 infectivity through suppression of ACE2 expression.

Immunogenic analysis of epitope-based vaccine candidate induced by photodynamic therapy in MDA-MB-231 triple-negative breast cancer cells

BACKGROUND

Photodynamic therapy (PDT) is used to treat tumors through selective cytotoxic effects. PDT induces damage-associated molecular patterns (DAMPs) expression, which can cause an immunogenic death cell (IDC). In this study we identified potential immunogenic epitopes generated by PDT on triple-negative breast cancer cell line (MDA-MB-231).

METHODS

MDA-MB-231 cells were exposed to PDT using ALA (160 µg/mL)/630 nm at 8 J/cm². Membrane proteins were extracted and separated by 2D PAGE. Proteins overexpressed were identified by LC-MS/MS and analyzed in silico through a peptide-HLA docking in order to identify the epitopes with more immunogenicity and antigenicity properties, as well as lower allergenicity and toxicity activity. The selected peptides were evaluated in response to macrophage activation and cytokine release by flow cytometry.

RESULTS

Differential proteins were overexpressed in the cells treated with PDT. A group of 16 peptides were identified from them, established in a rigorous selection by measuring antigenicity, immunogenicity, allergenicity, and toxicity in silico. The final selection was based on molecular dynamics, where 2 peptides showed the highest stability regarding to the RMSD value. These peptides were obtained from the proteins calreticulin and HSP90. The cytokine analysis evidenced macrophage activation by the releasing of TNF.

CONCLUSION

Two peptides were identified from calreticulin and HSP90; proteins induced by PDT in MDA-MB-231 cells. Both epitopes showed immunogenic potential as a peptide-based vaccine for triple-negative breast cancer.

5-Aminolevulinic Acid and Red Led in Endodontics: A Narrative Review and Case Report

The present study aims to discuss the main factors involving the use of 5-aminolevulinic acid together with red LED light and its application in endodontic treatment through a narrative review and a case report. Persistence of microorganisms remaining on chemical-mechanical preparation or intracanal dressing is reported as the leading cause of failure in endodontics. Photodynamic therapy has become a promising antimicrobial strategy as an aid to endodontic treatment. Being easy and quick to apply, it can be used both in a single session and in several sessions, as well as not allowing forms of microbial resistance. 5-aminolevulinic acid in combination with red LED light has recently been studied in many branches of medicine, with good results against numerous types of bacteria including Enterococuss faecalis. The case report showed how bacterial count of CFU decreased by half (210 CFU/mL), after 45 min of irrigation with a gel containing 5% of 5-aminolevulinic acid compared to the sample before irrigation (420 CFU/mL). The subsequent irradiation of red LED light for 7 min, the bacterial count was equal to 0. Thus, it is concluded that the use of 5-aminolevulinic acid together with red LED light is effective in endodontic treatment.

Photodynamic Therapy by Mean of 5-Aminolevulinic Acid for the Management of Periodontitis and Peri-Implantitis: A Retrospective Analysis of 20 Patients

Periodontitis and peri-implantitis are common in the population worldwide. Periodontal diseases affect approximately 50% of adults, while mucositis affects 80% of patients with implants, turning into peri-implantitis at a rate varying from 28 to 58%. If standardized treatments for all degrees and variety of periodontal diseases are known and codified, a consensus on the treatment of peri-implantitis still has to be found. Photodynamic therapy (PDT) has been used successfully in the medical field and was recently introduced as supportive therapy in dentistry. This paper reviews the results on 20 patients, 10 affected by periodontal disease (grades II to III) and 10 by peri-implantitis. Application of 5% 5-aminolevulinic acid gel (ALAD), as a support of causal therapy, in periodontal pockets and areas of peri-implantitis favored the maintenance of severely compromised teeth and significantly improved compromised implant conditions. Between baseline and 6 months, all teeth and implants remained functional. All patients confirmed that the scaling and root planning (SRP)+ALAD-PDT was not painful, and all perceived a benefit after the treatment at all timing points. For periodontal patients, a significant decrease in PPD after 3 (p < 0.001) and 6 months after SRP+ALAD-PDT respect baseline values were observed. For the implant patients, the SRP+ALAD-PDT was correlated to a decrease in PPD and BOP, and a slight increase in the number of exposed threads. However, the results were statistically significant only for PPD (p < 0.001).

An Update on Photodynamic Therapy of Psoriasis—Current Strategies and Nanotechnology as a Future Perspective

Psoriasis (PS) is an immune-mediated skin disease with substantial negative effects on patient quality of life. Despite significant progress in the development of novel treatment options over the past few decades, a high percentage of patients with psoriasis remain undertreated and require new medications with superior long-term efficacy and safety. One of the most promising treatment options against psoriatic lesions is a form of phototherapy known as photodynamic therapy (PDT), which involves either the systemic or local application of a cell-targeting photosensitizing compound, followed by selective illumination of the lesion with visible light. However, the effectiveness of clinically incorporated photosensitizers in psoriasis treatment is limited, and adverse effects such as pain or burning sensations are frequently reported. In this study, we performed a literature review and attempted to provide a pooled estimate of the efficacy and short-term safety of targeted PDT in the treatment of psoriasis. Despite some encouraging results, PDT remains clinically underutilized. This highlights the need for further studies that will aim to evaluate the efficacy of a wider spectrum of photosensitizers and the potential of nanotechnology in psoriasis treatment.

Suppression of resistance to aminolevulinic acid-based photodynamic therapy in esophageal cell lines by administration of iron chelators in collagen type I matrices

PURPOSE

Photodynamic therapy (PDT) utilizes visible light to activate the cytotoxic effects of photosensitizing drugs. PDT protocols require optimization to overcome treatment resistance and induce a beneficial anti-tumor immune response. The aim of this study was to examine the possibility to suppress the resistance of esophageal cell lines to aminolevulinic acid (ALA)-PDT by administration of iron chelators to induce sufficient cell cytotoxicity under pathophysiologically relevant conditions, mimicking the advanced stages of cancer.

MATERIALS AND METHODS

Effects of ALA-PDT in combination with iron chelators were compared in three esophageal cell lines in conventional monolayers and in 3 D cultures based on collagen type I. Modified colony assay and fluorescence-based live cell imaging, respectively were applied. The latter was used also to test the capability of pre-polarized macrophages to interact with cancer cells subjected to ALA-PDT with or without iron chelators.

RESULTS

Iron chelators were effective in the enhancement of ALA-PDT in all cell lines under both culture conditions. Fluorescence evaluation of cell viability in 3 D cultures indicated the contribution of apoptotic cell death after ALA-PDT, both with and without iron chelators. Engulfment of remnants of dead cancer cells by macrophages in 2 D cultures was indicated, however, the interaction between macrophages and cancer cells in 3 D cultures subjected to ALA-PDT with or without iron chelators was not present.

CONCLUSIONS

The potential of iron chelators to enhance ALA-PDT was maintained in 3 D collagen matrices. Although PDT dose (ALA concentration, light exposure time) required modification in a cell line-dependent manner to achieve a comparable effect of PDT alone in conventional monolayers and in collagen matrices, the potential of iron chelators to suppress the resistance of esophageal cells to ALA-PDT was not influenced by a fibrillar collagen matrix.

Purification and biofabrication of 5-aminolevulinic acid for photodynamic therapy against pathogens and cancer cells

5-Aminolevulinic acid (5-ALA) is a non-proteinogenic amino acid which has involved in heme metabolism of organisms, and has been widely applied in agriculture, and medical fields nowadays. 5-ALA is used in the elimination of pathogens or cancer cells by photodynamic therapy (PDT) owing to the photosensitizer reaction which releases the reactive oxygen species (ROS). Currently, biofabrication of 5-ALA is regarded as the most efficient and eco-friendly approach, but the complicated ingredient of medium causes the nuisance process of purification, resulting in low recovery and high producing cost. In this study, hydrogen chloride, sodium acetate, and ammonia were examined to maximize the recovery of 5-ALA from ion-exchange chromatography (IEC), thus a 92% recovery in 1 M ammonia at pH 9.5 was obtained. Afterward, the activated carbon was used for decolorization to further remove the pigments from the eluent. Four organic solvents, i.e., diethyl ether, methanol, ethanol, and acetone were compared to extract and form 5-ALA precipitation. The purified 5-ALA was verified to eliminate 74% of A549 human lung cancer and 83% of A375 melanoma skin cancer cell. Moreover, Proteus hauseri, Aeromonas hydrophila, Bacillus cereus, and Staphylococcus aureus were killed via anti-microbial PDT with 1% 5-ALA and reached 100% killing rate at optimal condition. With the addition of 0.05% 5-ALA during the culture, the growth of microalgae Chlorella sorokiniana was improved to against a common aquatic pathogen, A. hydrophila. The broad application of 5-ALA was demonstrated in this study for the first time.

Mechanisms of Resistance to Photodynamic Therapy (PDT) in Vulvar Cancer

Photodynamic therapy (PDT) is a valuable treatment method for vulvar intraepithelial neoplasia (VIN). It allows for the treatment of a multifocal disease with minimal tissue destruction. 5-Aminolevulinic acid (5-ALA) is the most commonly used prodrug, which is converted in the heme pathway to protoporphyrin IX (PpIX), an actual photosensitizer (PS). Unfortunately, not all patients treated with PDT undergo complete remission. The main cause of their failure is resistance to anticancer therapy. In many cancers, resistance to various anticancer treatments is correlated with increased activity of the DNA repair protein apurinic/apyrimidinic endonuclease 1 (APE1). Enhanced activity of drug pumps may also affect the effectiveness of therapy. To investigate whether multidrug resistance mechanisms underlie PDT resistance in VIN, porphyrins were isolated from sensitive and resistant vulvar cancer cells and their culture media. APE1 activity was measured, and survival assay after PDT combined with APE1 inhibitor was performed. Our results revealed that resistant cells accumulated and effluxed less porphyrins than sensitive cells, and in response to PDT, resistant cells increased APE1 activity. Moreover, PDT combined with inhibition of APE1 significantly decreased the survival of PDT-resistant cells. This means that resistance to PDT in vulvar cancer may be the result of alterations in the heme synthesis pathway. Moreover, increased APE1 activity may be essential for the repair of PDT-mediated DNA damage, and inhibition of APE1 activity may increase the efficacy of PDT.

Photodynamic Therapy Using 5-Aminolevulinic Acid (Ala) for the Treatment of Chronic Periodontitis: A Prospective Case Series

Aim: The objective of this study was to compare the efficacy of supportive periodontal therapy (i.e., scaling and root planning, SRP) alone versus ALADENT medical device used in association with SRP in the treatment of chronic periodontitis in adult patients. Materials and Methods: A total of 20 patients with a diagnosis of chronic periodontitis (40 localized chronic periodontitis sites) aged between 35 and 55 were selected. None of these patients previously received any surgical or non-surgical periodontal therapy, and they presented radiographic evidence of moderate bone loss. Two non-adjacent sites in different quadrants were identified and observed in each patient, analyzing treatment effectiveness (split-mouth design). Clinical pocket depth, clinical attachment loss, and bleeding on probing were evaluated at time 0 and after 6 months, while microbial analysis (MA) was conducted at baseline and after 15 days. Significant differences were calculated using SPSS program and paired simple statistic t-test. Results: Total bacteria loadings had a statistically significant reduction before and after treatment with SRP (left site) (total average decrease of 27%). The sites treated with SRP plus ALADENT (right) showed a significantly reduced total bacterial loading compared to the untreated sites (right) (total average decrease of 75%). Mean values of CAL/PD and percentages data of BOP, recorded after SRP + ALADENT therapy, showed a higher reduction (CAL = 2.42, PD = 2.87 mm, 90% of sites with no bleeding) than those obtained after SRP treatment (CAL = 4.08 mm, PD = 4.73 mm, 70% of sites with no bleeding). Conclusion: The treatment of moderate and severe chronic periodontitis should include, beside SRP, the use of ALADENT medical device, which has been proved to be a useful adjuvant therapy.

Mesoporous Silica-Coated Upconversion Nanoparticles Assisted Photodynamic Therapy Using 5-Aminolevulinic Acid: Mechanistic and In Vivo Studies

Exclusively red-emitting upconversion nanoparticles (UCNPs) with the composition NaErF₄:0.5%Tm as a core and NaYF₄ as a shell were synthesized for performing photodynamic therapy (PDT). A possible mechanism was proposed for core-shell UCNPs formation. For loading a maximum amount of 5-aminolevulinic acid (5-ALA), mesoporous silica coating was performed on UCNPs. Studies under dark conditions confirmed the biocompatibility of 5-ALA-loaded UCNPs formulation (UCNPs-5-ALA) with MCF-7 cells. Meanwhile, studies under light-exposed conditions exhibited effective cytotoxicity against MCF-7 cells. Studies employing D₂O-based cell cultured media and addition of DABCO in cell culture established that the cell death was due to oxidation of cellular components by reactive oxygen species (ROS) triggering the apoptosis. The formation of ROS was confirmed by DCF(H)DA-based ROS analysis via fluorescence microscopy to demonstrate the ROS production, which mediates the programmed cell death. Additionally, we have validated the apoptosis in MCF-7 cells with flow cytometry analyses. This was further confirmed by an electrophoretic mobility shift assay on nuclear extract and measurement of mitochondrial membrane potential. In the case of animal model studies, the formulation UCNPs-5-ALA without irradiation (980 nm) did not possess any in vivo cytotoxicity on tumor-induced SCID mice and there was a minimum migration of UCNPs-5-ALA to the vital organs but maximum retention at the tumor site only. Meanwhile, only the mice treated with UCNPs-5-ALA and irradiated on the tumor region with 980 nm laser (500 mW) for 20 min possessed a tumor with a size reduced to about 75% as compared with the corresponding control groups. To the best of our knowledge, this type of study was conducted for the first time employing exclusively red-emitting phosphors for effective PDT.

Stimulation and homogenization of the protoporphyrin IX endogenous production by photobiomodulation to increase the potency of photodynamic therapy

Protoporphyrin IX (PpIX) is produced in the mitochondria and used as fluorescent contrast agent or photosensitizer after exogenous 5-aminolevulinic acid (ALA) delivery in cancer photodynamic detection and therapy (PDT). Although routinely used in the clinics, the stimulated production of PpIX is often insufficient and/or heterogeneous within the lesions, thereby limiting the PDT performances. Since photobiomodulation, which is based on the illumination of the tissues with sub-thermal radiometric conditions in the red or near-infrared, is known to stimulate the cell metabolism, we have optimized these conditions in vitro. Some of them lead to the homogenization and strong stimulation of the PpIX endogenous production. Interestingly, combined sequentially, PBM enhanced significantly the potency of PpIX-based PDT in vitro and in vivo in tumors grown on the chicken embryo chorioallantoic membrane. These results are in excellent agreement with other assays based on measurements of the cell survival/death, the production of reactive oxygen species, including singlet oxygen, and the mitochondrial membrane potential.

5-Aminolevulinic Acid Triggered by Ultrasound Halts Tumor Proliferation in a Syngeneic Model of Breast Cancer

Sonodynamic therapy is a bimodal therapeutic approach in which a chemical compound and ultrasound (US) synergistically act to elicit oxidative damage, triggering cancer cell death. Despite encouraging results, mainly for anticancer treatment, sonodynamics is still far from having a clinical application. Therefore, to close the gap between the bench and bedside, more in vivo studies are needed. In this investigation, the combined effect of 5-aminolevulinic acid (Ala), a natural porphyrin precursor, plus exposure to US, was investigated in vivo on a syngeneic breast cancer model. Real-time RT-PCR, Western blotting, and immunohistochemistry assays were performed to evaluate the effect of sonodynamic treatment on the main cancer hallmarks. The sonodynamic-treated group had a significant reduction (p ≤ 0.0001) in tumor size compared to the untreated group, and the Ala- and US-only treated groups, where a strong decrease (p ≤ 0.0001) in Ki67 protein expression was the most relevant feature of sonodynamic-treated cancer tissues. Moreover, oxidative stress was confirmed as the pivotal driver of the anticancer effect through cell cycle arrest, apoptosis, and autophagy; thus, sonodynamics should be explored further for cancer treatment.

Simultaneous exposure to intracellular and extracellular photosensitizers for the treatment of Staphylococcus aureus infections

Staphylococcus aureus is a serious threat to public health due to the rise of antibiotic resistance in this organism, which can prolong or exacerbate skin and soft tissue infections (SSTIs). Methicillin-resistant S. aureus is a Gram-positive bacterium and a leading cause of SSTIs. As such, many efforts are underway to develop therapies that target essential biological processes in S. aureus. Antimicrobial photodynamic therapy is effective alternative to antibiotics, therefore we developed an approach to simultaneously expose S. aureus to intracellular and extracellular photoactivators. A near infrared photosensitizer was conjugated to human monoclonal antibodies (mAbs) that target the S. aureus Isd heme acquisition proteins. Additionally, the compound VU0038882 was developed to increase photoactivatable porphyrins within the cell. Combinatorial PDT treatment of drug-resistant S. aureus exposed to VU0038882 and conjugated anti-Isd mAbs proved to be an effective antibacterial strategy in vitro and in a murine model of SSTIs.

Photodynamic Therapy: A Compendium of Latest Reviews

Photodynamic therapy (PDT) is a promising therapy against cancer. Even though it has been investigated for more than 100 years, scientific publications have grown exponentially in the last two decades. For this reason, we present a brief compendium of reviews of the last two decades classified under different topics, namely, overviews, reviews about specific cancers, and meta-analyses of photosensitisers, PDT mechanisms, dosimetry, and light sources. The key issues and main conclusions are summarized, including ways and means to improve therapy and outcomes. Due to the broad scope of this work and it being the first time that a compendium of the latest reviews has been performed for PDT, it may be of interest to a wide audience.

Mechanism of Differential Susceptibility of Two (Canine Lung Adenocarcinoma) Cell Lines to 5-Aminolevulinic Acid-Mediated Photodynamic Therapy

Photodynamic therapy (PDT) is a clinically approved, minimally invasive treatment for malignant tumors. Protoporphyrin IX (PpIX), derived from 5-aminolevulinic acid (5-ALA) as the prodrug, is one of the photosensitizers used in PDT. Recently, we reported a significant difference in response to 5-ALA-mediated PDT treatment in two canine primary lung adenocarcinoma cell lines (sensitive to PDT: HDC cells, resistant to PDT: LuBi cells). This study aimed to examine the difference in cytotoxicity of 5-ALA-mediated PDT in these cells. Although intracellular PpIX levels before irradiation were similar between HDC and LuBi cells, the percentage of ROS-positive cells and apoptotic cells in LuBi cells treated with 5-ALA-mediated PDT was significantly lower than that in HDC cells treated with 5-ALA-mediated PDT. A high dosage of the NO donor, DETA NONOate, significantly increased the cytotoxicity of 5-ALA-mediated PDT against LuBi cells. These results suggest that the sensitivity of 5-ALA-mediated PDT might be correlated with NO.

Investigation of the therapeutic effect of 5-aminolevulinic acid based photodynamic therapy on hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a heterogeneous type of cancer and current treatment options limit successful therapy outcomes. Photodynamic therapy (PDT) has attracted attention as an alternative approach in the treatment of different types of cancer. However, there is no study in the literature regarding the effect of PDT on HCC, in vitro. Therefore, the aim of this study was to determine the cytotoxic and apoptotic effects of 5-aminolevulinic acid (5-ALA)/PDT on two different HCC cell lines in terms of hepatitis B virus (HBV) infection. The therapeutic effects of 5-ALA-based PDT on HCC cell lines (Huh-7 and SNU-449) were evaluated by PpIX-fluorescence accumulation, WST-1 analysis, Annexin V analysis, and acridine orange/ethidium bromide staining after irradiation with different light doses through diode laser. The results showed that 1 mM 5-ALA displayed higher PpIX fluorescence in the SNU-449 cell line than the Huh-7 cell line after 4 h of incubation. After irradiation with different light doses (3, 6, 9, and 12 J/cm²), 5-ALA significantly reduced the proliferation of HCC cells and induced apoptotic cell death (p < 0.01). Furthermore, SNU-449 cells were more responsive to 5-ALA-based PDT than Huh-7 cells due to possibly its molecular features as well as viral HBV status. Our preliminary data obtained from this study may contribute to the development of 5-ALA/PDT-based treatment strategies in the treatment of HCC. However, this study could be improved by the elucidation of the molecular mechanisms of cell death induced by 5-ALA/PDT in HCC cells, the use of different photosensitizer, light sources, and in vivo experiments.

Nanocarriers for Photodynamic Therapy Intended to Cutaneous Tumors

Photodynamic Therapy (PDT) is a therapeutic modality used for several malignant and premalignant skin disorders, including Bowen's disease skin cancers and Superficial Basal Cell Carcinoma (BCC). Several photosensitizers (PSs) have been explored for tumor destruction of skin cancers, after their activation by a light source of appropriate wavelength. Topical release of PSs avoids prolonged photosensitization reactions associated with systemic administration; however, its clinical usefulness is influenced by its poor tissue penetration and the stability of the active agent. Nanotechnology-based drug delivery systems are promising tool to enhance the efficiency for PDT of cancer. This review focuses on PSs encapsulated in nanocarriers explored for PDT of skin tumors.

Using a Hybrid Radioenhancer to Discover Tumor Cell-targeted Treatment for Osteosarcoma: An In Vitro Study

Osteosarcoma is insensitive to radiation. High-dose radiation is often used as a treatment but causes side effects in patients. Hence, it is important to develop tumor cell-- targeted radiotherapy that could improve radiotherapy efficiency on tumor cells and reduce the toxic effect on normal cells during radiation treatment. In this study, we developed an innovative method for treating osteosarcoma by using a novel radiation-enhancer (i.e., carboxymethyl-hexanoyl chitosan-coated self-assembled Au@Fe3O4 nanoparticles; CSAF NPs). CSAF NPs were employed together with 5-aminolevulinic acid (5- ALA) to achieve tumor cell-targeted radiotherapy. In this study, osteosarcoma cells (MG63) and normal cells (MC3T3-E1) were used for an in vitro investigation, in which reactive oxygen species (ROS) assay, cell viability assay, clonogenic assay, and western blot were used to confirm the treatment efficiency. The ROS assay showed that the combination of CSAF NPs and 5-ALA enhanced radiation-induced ROS production in tumor cells (MG63); however, this was not observed in normal cells (MC3T3-E1). The cell viability ratio of normal cells to tumor cells after treatment with CSAF NPs and 5-ALA reached 2.79. Moreover, the clonogenic assay showed that the radiosensitivity of MG63 cells was increased by the combination use of CSAF NPs and 5-ALA. This was supported by performing a western blot that confirmed the expression of cytochrome c (a marker of cell mitochondria damage) and caspase-3 (a marker of cell apoptosis). The results provide an essential basis for developing tumor-cell targeted radiotherapy by means of low-- dose radiation.

The heme synthesis-export system regulates the tricarboxylic acid cycle flux and oxidative phosphorylation

Heme is an iron-containing porphyrin of vital importance for cell energetic metabolism. High rates of heme synthesis are commonly observed in proliferating cells. Moreover, the cell-surface heme exporter feline leukemia virus subgroup C receptor 1a (FLVCR1a) is overexpressed in several tumor types. However, the reasons why heme synthesis and export are enhanced in highly proliferating cells remain unknown. Here, we illustrate a functional axis between heme synthesis and heme export: heme efflux through the plasma membrane sustains heme synthesis, and implementation of the two processes down-modulates the tricarboxylic acid (TCA) cycle flux and oxidative phosphorylation. Conversely, inhibition of heme export reduces heme synthesis and promotes the TCA cycle fueling and flux as well as oxidative phosphorylation. These data indicate that the heme synthesis-export system modulates the TCA cycle and oxidative metabolism and provide a mechanistic basis for the observation that both processes are enhanced in cells with high-energy demand.

Photodynamic viral inactivation: Recent advances and potential applications

Antibiotic-resistant bacteria, which are growing at a frightening rate worldwide, has put the world on a long-standing alert. The COVID-19 health crisis reinforced the pressing need to address a fast-developing pandemic. To mitigate these health emergencies and prevent economic collapse, cheap, practical, and easily applicable infection control techniques are essential worldwide. Application of light in the form of photodynamic action on microorganisms and viruses has been growing and is now successfully applied in several areas. The efficacy of this approach has been demonstrated in the fight against viruses, prompting additional efforts to advance the technique, including safety use protocols. In particular, its application to suppress respiratory tract infections and to provide decontamination of fluids, such as blood plasma and others, can become an inexpensive alternative strategy in the fight against viral and bacterial infections. Diverse early treatment methods based on photodynamic action enable an accelerated response to emerging threats prior to the availability of preventative drugs. In this review, we evaluate a vast number of photodynamic demonstrations and first-principle proofs carried out on viral control, revealing its potential and encouraging its rapid development toward safe clinical practice. This review highlights the main research trends and, as a futuristic exercise, anticipates potential situations where photodynamic treatment can provide a readily available solution.

Increased DNA repair capacity augments resistance of glioblastoma cells to photodynamic therapy

Photodynamic therapy (PDT) is a clinically approved cancer therapy of low invasiveness. The therapeutic procedure involves administering a photosensitizing drug (PS), which is then activated with monochromatic light of a specific wavelength. The photochemical reaction produces highly toxic oxygen species. The development of resistance to PDT in some cancer cells is its main limitation. Several mechanisms are known to be involved in the development of cellular defense against cytotoxic effects of PDT, including activation of antioxidant enzymes, drug efflux pumps, degradation of PS, and overexpression of protein chaperons. Another putative factor that plays an important role in the development of resistance of cancer cells to PDT seems to be DNA repair; however, it has not been well studied so far. To explore the role of DNA repair and other potential novel mechanisms associated with the resistance to PDT in the glioblastoma cells, cells stably resistant to PDT were isolated from PDT sensitive cells following repetitive PDT cycles. Duly characterization of isolated PDT-resistant glioblastoma revealed that the resistance to PDT might be a consequence of several mechanisms, including higher repair efficiency of oxidative DNA damage and repair of DNA breaks. Higher activity of APE1 endonuclease and increased expression and activation of DNA damage kinase ATM was demonstrated in the U-87 MGR cell line, suggesting and proving that they are good targets for sensitization of resistant cells to PDT.