No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
How Does Photodynamic Therapy Work?
... PDT works through the combination of 3 key elements: a photosensitizer, a light source and oxygen. It is performed with topical application of the photosensitizer, which is selectively absorbed by neoplastic cells due to their altered metabolism [28][29][30]. The most commonly used photosensitizing agents are 5-aminolevulinic acid (5-ALA) and its ester, methyl aminolevulinate (MAL) which are both precursors of the heme biosynthetic pathway. ...
... Following the application, ALA is converted into photoactivatable porphyrins, specifically protoporphyrin IX (PpIX), in the epidermis and irradiation at pre-defined wavelengths of red, blue or broadband light source causes cytotoxicity mediated by an oxygen-dependent phototoxic reaction and reactive oxygen species (ROS). This process results in the death of the targeted cells through apoptosis, necrosis, or autophagy ( Figure 1) [29][30][31][32]. A commonly used licensed regimen consists of 2 treatment cycles of PDT, 1 week apart, usually with light curettage of BCCs before the application of the photosensitizer. ...
Introduction:
Basal cell carcinoma (BCC) is the most common skin cancer worldwide and has been reported to have a rising incidence in the last years. Multiple therapeutic modalities are approved for the treatment of BCC, making it difficult for physicians to choose the most suitable option for every patient. Photodynamic therapy (PDT) using either 5-aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) as photosensitizing agents is an established treatment option for low-risk BCC.
Objectives:
This review aims to summarize the available evidence from randomized clinical trials (RCTs) that utilize either ALA or MAL PDT and compare it with other treatment modalities. The main outcomes related to the effectiveness, adverse events, cosmetic outcomes and pain sensation, along with data from long-term follow-ups will be presented and discussed.
Methods:
Thorough literature searches were conducted through the electronic databases ClinicalTrials. gov and Pubmed/MEDLINE from inception up to 28 March 2023. Only studies in English were included. All relevant data were extracted accordingly from the eligible studies.
Results:
Eight RCTs included superficial BCC (sBCC) alone, 7 included nodular BCC (nBCC), 2 included both sBCC and nBCC and 1 included BCC of unspecified subtype. Follow-up duration ranged from 3 months to 5 years. Both ALA-PDT and MAL-PDT demonstrated acceptable efficacy, adverse events, cosmetic outcomes and pain sensation while no major differences were observed between them. PDT was less effective than surgery but with better reported cosmetic outcomes.
Conclusions:
PDT is a safe and efficacious treatment option for sBCC and to a lesser extent nBCC.
... The basic principle involves the administration of a photosensitizing agent, which accumulates in the target tissue, followed by exposure to light of a specific wavelength [5]. This activates the photosensitizer, leading to the production of reactive oxygen species (ROS) and the induction of localised cytotoxic effects [6]. ...
... Photodynamic treatment (PDT) is a type of therapy that uses a photosensitizing agent and light to target and destroy abnormal cells, including those involved in immune system diseases [1][2][3][4][5][6][7][8][9][10][11][12]. The mechanisms of PDT in immune system diseases involve several key processes. ...
Photodynamic treatment (PDT) has emerged as a promising therapeutic approach for immune system diseases due to its ability to selectively target abnormal cells while modulating the immune response. This review explores the mechanisms by which PDT activates the immune system to target diseased cells, including the induction of immunogenic cell death, activation of dendritic cells, release of tumor-associated antigens, modulation of immune checkpoints, and induction of cytokines and chemokines. Additionally, PDT can generate reactive oxygen species, induce apoptosis, and exhibit anti-inflammatory and vascular effects, all of which contribute to its therapeutic potential in immune system diseases [1]. Harnessing PDT for immune system diseases offers a unique opportunity to leverage the immune system's inherent ability to recognize and eliminate abnormal cells, providing a targeted and potentially less toxic treatment option. Further research and clinical studies are warranted to fully elucidate the potential of PDT in the management of immune system diseases and to optimize its clinical application.
... PDT employs an agent which is photosensitizing (PS) whose activation occurs through light, and then, it is transposed to the site of the tumor [186]. Particularly, the laser light of an appropriate wavelength is used for the excitation of localized PS to form a single photosensitizer (PS * ) with an excited state [187]. After which, the PS * goes through an intercrossing between systems to synthesize a triplet excited state (PS * * ), which can (i) stimulate the transfer of electrons to the neighboring area and release ROS (especially O2•− or •OH, which are free radicals) indicated as type I or II or, (ii) go through the procedure of transfer of energy with the ground state (3O2) to form singlet oxygen (O2), indicated type II [187]. ...
... Particularly, the laser light of an appropriate wavelength is used for the excitation of localized PS to form a single photosensitizer (PS * ) with an excited state [187]. After which, the PS * goes through an intercrossing between systems to synthesize a triplet excited state (PS * * ), which can (i) stimulate the transfer of electrons to the neighboring area and release ROS (especially O2•− or •OH, which are free radicals) indicated as type I or II or, (ii) go through the procedure of transfer of energy with the ground state (3O2) to form singlet oxygen (O2), indicated type II [187]. Thus, these ROS which are generated by NMs can then destruct the essential biomolecules of the tumor, which act as cytotoxic substances if especially applied to cancer cells. ...
Nanotechnology has become one of the most extensive fields of research. Nanoparticles (NPs) form the base for nanotechnology. Recently, nanomaterials (NMs) are widely used due to flexible chemical, biological, and physical characteristics with improved efficacy in comparison to bulk counterparts. The significance of each class of NMs is enhanced by identifying their properties. Day by day, there is an emergence of various applications of NMs, but the toxic effects associated with them cannot be avoided. NMs demonstrate therapeutic abilities by enhancing the drug delivery system, diagnosis, and therapeutic effects of numerous agents, but determining the benefits of NMs over other clinical applications (disease-specific) or substances is an ongoing investigation. This review is aimed at defining NMs and NPs and their types, synthesis, and pharmaceutical, biomedical, and clinical applications.
... Photodynamic therapy (PDT) is a principally new method of treating malignant tumors based on the use of photodynamical damage of tumor cells under a photochemical reaction (1)(2)(3) . During last several years, the whole range of dyes such as Photofrin (USA and Canada), Photoscan (Germany), HPD (China), Photogem (Russia), Benzoporphyrin derivative (Canada), 5-aminolevulenic acid (Europe and USA), Aspartate chlorine E6 (Japan), and others are used as photosensitizers for the wide range of malignant tumors as well as nonmalignant diseases (4)(5)(6) . ...
In order to elucidate the antitumor effect of photodynamic therapy (PDT) using the photosensitizing agent hematoporphyrin derivative (Photogem) and a diode laser, we evaluated the cell death of uterine cancer cell lines (CaSki, HT3, HeLa, and SKOV-3) and mice transplanted with TC-1 lung cancer cells. Morphological changes, MTT assay, flow cytometry, cytotoxicity, and tumor growth-inhibition study were evaluated at various time intervals after PDT. The results showed that the survival rates of each cell line decreased with time and dose–response after performing PDT. Also, PDT-induced damage of cancer cells was almost entirely confined to necrosis of the tumor cells in the early time courses. The irradiation of CaSki cells in the presence of Photogem induced plasma membrane disruption and cell shrinkage, indicating the plasma membrane as the main target for Photogem. In the experiment in vivo, the time courses of Photogem with irradiation showed significantly longer survival and a significantly smaller tumor size compared to those in the untreated control groups, and resorption of the tumor after PDT treatment was observed. Collectively, our results indicated that Photogem possesses tumor-specific affinity, and necrosis-like death with plasma membrane damage was postulated to be the principal mechanism of the antitumor effect of PDT using Photogem.
... Energy transfer from the T 1 state of the PS dye to molecular oxygen results in the generation of 1 O 2 , which is the main cytocidal agent in the destruction of tumor cells. [17,34,35] In this study, we report a study of the PACT activities of a series of indium tetraarylporphyrins (1-4-InPor) with sulfurcontaining meso-aryl rings (Scheme 1). Incorporation of a heavy atom, such as indium, is known to enhance the triplet population due to spin-orbit coupling, resulting in better singlet oxygen generation, [3,4] and the presence of an axial ligand helps to prevent aggregation. ...
In(III) tetraarylporphyrin complexes with 4‐thiomethylphenyl (1‐InPor), thien‐3‐yl (2‐InPor), thien‐2‐yl (3‐InPor) and 5‐bromothien‐2‐yl (4‐InPor) meso‐aryl rings have been synthesized and characterized. The complexes have been conjugated to gold and silver nanoparticles (AuNPs and AgNPs). The photodynamic antimicrobial chemotherapy (PACT) activities of 1–4‐InPor and their AuNP and AgNP conjugates have been investigated against both planktonic bacteria and biofilms of Gram‐(+) S. aureus and Gram‐(−) E. coli. 2.5 μg.mL⁻¹ solutions of 1–4‐InPor exhibited favorable PACT activities against planktonic S. aureus with high Log10 reduction values in the 4.28–7.69 range upon 75 min photoirradiation with a Thorlabs M625L3 LED (240 mW.cm⁻²) mounted onto the illumination chamber of a Modulight 7710 medical laser system to provide a dose at the well‐plate of 86 mJ.cm⁻².min⁻¹. In contrast, low values in the 1.4–1.9 range were obtained against E. coli with 10 μg.mL⁻¹ solutions. 1–4‐InPor exhibited relatively low PACT activity against the biofilm cells of S. aureus and E. coli. Conjugation of 1–4‐InPor to AgNPs and AuNPs significantly enhanced the PACT activities. This is demonstrated by the complete eradication of planktonic S. aureus at shorter irradiation times with high Log10 values>7.69 and moderate Log10 values>2 against planktonic E. coli for the meso‐thienylporphyrin conjugates.
... PDT consists of the activation of a photosensitizing drug by visible light. The sensitizer, when irradiated, generates reactive oxygen species, such as singlet oxygen, the hydroxyl radical, the superoxide anion and hydrogen peroxide, which have a direct cytotoxic effect, and stimulate the release of immune mediators, resulting in additional pro-inflammatory effects [29,30]. In dermatologic indications, PDT uses precursors of the heme biosynthetic pathway, particularly 5-aminolaevulinic acid (5-ALA) or its ester, methyl aminolaevulinate (MAL), as photosensitizers, which are converted within target cells into protoporphyrin IX (PpIX) and activated through a light source. ...
Bowen’s disease represents the in situ form of cutaneous squamous cell carcinoma; although it has an excellent prognosis, 3–5% of lesions progress to invasive cutaneous squamous cell carcinoma, with a higher risk in immunocompromised patients. Treatment is therefore always necessary, and conventional photodynamic therapy is a first-line option. The aim of this review is to provide an overview of the clinical response, recurrence rates, safety, and cosmetic outcome of photodynamic therapy in the treatment of Bowen’s disease, considering different protocols in terms of photosensitizers, light source, and combination treatments. Photodynamic therapy is a valuable option for tumors at sites where wound healing is poor/delayed, in the case of multiple and/or large tumors, and where surgery would be difficult or invasive. Dermoscopy and reflectance confocal microscopy can be used as valuable tools for monitoring the therapeutic response. The treatment is generally well tolerated, with mild side effects, and is associated with a good/excellent cosmetic outcome. Periodic follow-up after photodynamic therapy is essential because of the risk of recurrence and progression to cSCC. As the incidence of keratinocyte tumors increases, the therapeutic space for photodynamic therapy will further increase.
... The efficacy of PDT for cancer treatment is also influenced by factors such as the concentration and location of AuNPs within the tumor microenvironment, the intensity and wavelength of light used for illumination, the duration of illumination, the type of tumor being treated, and the level of oxygenation within the tumor. These variables must be carefully considered when designing PDT protocols to ensure optimal treatment outcomes (Dolmans et al., 2003;Dougherty et al., 1998;Henderson and Dougherty, 1992;Oleinick et al., 2002). Zhao et al. (2012) conducted a study to investigate the singlet oxygen generation efficiency of polyvinylpyrrolidone (PVP) coated AuNRs using different types and wavelengths of laser. ...
... The high prevalence of oral infections, coupled with the tolerance of oral biofilms against conventional agents, has driven research to the development of alternative and complementary strategies, such as Photodynamic Inactivation (PDI). The mechanism of PDI involves the use of a photosensitizing compound and visible light in the presence of oxygen, producing reactive oxygen species (type I) and singlet oxygen (type II) that are toxic to the target cells [22][23][24]. ...
This is a protocol for an overview to summarize the findings of Systematic Reviews (SR) dealing with Photodynamic Inactivation (PDI) for control of oral diseases. Specific variables of oral infectious will be considered as outcomes, according to dental specialty. Cochrane Database of Systematic Reviews (CDSR), MEDLINE, LILACS, Embase, and Epistemonikos will be searched, as well as reference lists. A search strategy was developed for each database using only terms related to the intervention (PDI) aiming to maximize sensitivity. After checking for duplicate entries, selection of reviews will be performed in a two-stage technique: two authors will independently screening titles and abstracts, and then full texts will be assessed for inclusion/exclusion criteria. Any disagreement will be resolved through discussion and/or consultation with a third reviewer. Data will be extracted following the recommendations in Chapter V of Cochrane Handbook and using an electronic pre-specified form. The evaluation of the methodological quality and risk of bias (RoB) of the SR included will be carried out using the AMSTAR 2 and ROBIS. Narrative summaries of relevant results from the individual SR will be carried out and displayed in tables and figures. A specific summary will focus on PDI parameters and study designs, such as the type and concentration of photosensitizer, pre-irradiation time, irradiation dosimetry, and infection or microbiological models, to identify the PDI protocols with clinical potential. We will summarize the quantitative results of the SRs narratively.
... In addition to surgical therapy and established local and systemic treatment modalities, such as chemotherapy and immunotherapy [2], there exists therapeutic modalities that are currently outside the scope of clinicians treating patients with urothelial carcinoma (UC). Despite substantial experience in other tumor entities and the wide clinical use of photodynamic diagnosis (PDD) for the transurethral resection of bladder tumor (TURBT), the potential of photodynamic therapy (PDT) for the treatment of UC has not been thoroughly investigated [3][4][5][6][7][8][9]. ...
Bladder cancer (BC) is the 10th most common cancer in the world. The therapeutic spectrum of BC is broad and is constantly expanding. Despite the wide clinical use of photodynamic diagnosis (PTD) for BC, PDT has not been sufficiently investigated in the treatment landscape of BC. We performed an online search of the PubMed database using these keywords: photodynamic therapy, bladder cancer, urothelial carcinoma, in vivo, in vitro, cell line, animal model. Reviews, case reports, and articles devoted to photodynamic diagnostics and the photodynamic therapy of tumors other than urothelial carcinoma were excluded. Of a total of 695 publications, we selected 20 articles with clinical data, 34 articles on in vivo PDT, and 106 articles on in vitro data. The results presented in animal models highlight the potential use of PDT in the neoadjuvant or adjuvant setting to reduce local recurrence in the bladder and upper urinary tracts. Possible regimens include the combination of PDT with intravesical chemotherapy for improved local tumor control or the integration of vascular-targeted PDT in combination with modern systemic drugs in order to boost local response. We summarize available evidence on the preclinical and clinical application of PDT for urothelial carcinoma in order to explain the current trends and future perspectives.
... Some of the possible biological sources of 1 O 2 generation are shown in Figure 13. Possible biological sources of O 2 ( 1 Δ g ) include (i) reactions catalyzed by peroxidases (myeloperoxidase) or oxygenases (lipoxygenases) [19,20], (ii) recombination of peroxyl radicals can lead to the release of 1 O 2 as a result of the decomposition of transient tetroxides according to Russell's concerted mechanism (Russell reaction) [6,21], (iii) oxidation with ozone of amino acids, peptides, and proteins, (iv) hydrogen peroxide reactions with hypochlorite or peroxynitrite, (v) ozone oxidation of amino acids, peptides, and proteins [22], (vi) hydrogen peroxide reactions with hypochlorite or peroxynitrite [23,24], (vii) thermolysis of endoperoxides [25][26][27][28][29][30][31][32][33][34][35], (vii) in vitro photodynamic processes involving type-II photosensitization reactions using suitable dyes [36][37][38], and (viii) UV irradiation of aromatic amino acids in proteins and immunoglobulins. ...
Reactive oxygen species (ROS) are molecules produced in living organisms, in the environment, and in various chemical reactions. The main species include, among others, singlet oxygen (1O2), the superoxide anion radical (•O2−), the hydroxyl radical (HO•), and the hydroperoxyl radical (HOO•). In general, the reactivity of 1O2 is lower than that of HO• but even higher than that of •O2−. Singlet oxygen is the lowest energy excited state of molecular oxygen, but it is also a highly reactive species, which can initiate oxidation reactions of biomolecules such as amino acids, proteins, nucleic acids, and lipids, either by a direct reaction or by the induction of ROS. Singlet oxygen is a highly reactive electrophilic species that reacts with electron-rich molecules and is related to several types of pathologies. To inhibit the oxidation of biomolecules with this species, some substances act as antioxidants by performing a quenching effect. In this chapter, aspects such as its physicochemical properties, methods of generation and detection, as well as the reactivity of this molecule are detailed.
... Both types of reactions can occur simultaneously, however, for tissue-based PS it is assumed that mechanism II is dominant and determines the effectiveness of therapy. The ROS generated is influenced by substrate and oxygen concentration, pH of the environment and dye quantum yield (Gomer and Razum, 1984;Henderson and Dougherty, 1992;Pass, 1993;Luksiene, 2003;Vrouenraets et al., 2003;Allison et al., 2006). Photodynamic therapy uses different wavelengths of visible light depending on the photosensitizer and its absorption range, as well as the desired depth of penetration of the light into the tissue. ...
Brain tumors, including glioblastoma multiforme, are currently a cause of suffering and death of tens of thousands of people worldwide. Despite advances in clinical treatment, the average patient survival time from the moment of diagnosis of glioblastoma multiforme and application of standard treatment methods such as surgical resection, radio- and chemotherapy, is less than 4 years. The continuing development of new therapeutic methods for targeting and treating brain tumors may extend life and provide greater comfort to patients. One such developing therapeutic method is photodynamic therapy. Photodynamic therapy is a progressive method of therapy used in dermatology, dentistry, ophthalmology, and has found use as an antimicrobial agent. It has also found wide application in photodiagnosis. Photodynamic therapy requires the presence of three necessary components: a clinically approved photosensitizer, oxygen and light. This paper is a review of selected literature from Pubmed and Scopus scientific databases in the field of photodynamic therapy in brain tumors with an emphasis on glioblastoma treatment.
... [6] It has shown promising results in many premalignant conditions such as oral lichen planus and carcinoma in situ. [18][19][20][21] At now, the efficacy of some PSs with different laser wavelengths on the death of malignant OSCC cells is not clear, thus this study was done to compare two PSs MB and ALA alone or with 660 nm laser on the death of malignant oral SCC cells. ...
Background
This study aimed to compare the effects of laser photodynamic therapy (PDT) with methylene blue (MB) or aminolevulinic acid (ALA) on the oral squamous cell carcinoma (OSCC) cell line.
Materials and Methods
In this in vitro experimental study, the C152 (KB) OSCC cell line was cultured in a culture medium containing 10% fetal bovine serum. The cells were exposed to 0.1, 0.2, 0.5, 1, 2, 5, and 10 mM concentrations of MB and ALA alone and combined with diode laser irradiation with 660 nm wavelength, 40 mW power, and 10 J/cm² energy density in continuous-wave mode perpendicular to the surface. Cell viability was assessed using the methyl thiazolyl tetrazolium assay and compared among the groups by the Kruskal–Wallis test.
Results
The results showed that the reduction in cell viability in the MB + laser and ALA + laser groups was greater than that in the MB and ALA groups without laser (P < 0.001). Significant differences were noted in cell viability in the presence of some different concentrations of MB and ALA (P < 0.05), such that by an increase in their concentration, cell viability decreased. Cell viability in the MB + laser group was significantly lower than that in the ALA + laser group in some photosensitizer concentrations (P < 0.05).
Conclusion
Within the limitations of this in vitro study, the results showed that laser PDT with MB (high concentrations) was more effective than laser PDT with ALA against the OSCC cell line.
... Thus, 5-ALA is a precursor of the endogenous photosensitizer PP IX. PP IX is a rather active photosensitizer due to the presence of an intense absorption band with a maximum at a wavelength of 635 nm and the ability to efficiently generate singlet oxygen and reactive oxygen species providing photo-injury of vessels, including MLVs [53][54][55]. Figure 6 clearly demonstrates the effective photo-injury of MLVs by 5-ALA-PDT in all mice. Indeed, the coverage of LYVE-1 positive vessels along the sagittal and transverse sinuses was 5.7-fold lesser (p < 0.001) in the 5-ALA + Laser (photo-ablation, n = 9) vs. the 5-ALA without Laser (control, n = 12) groups. ...
With the increase in the aging population, the global number of people with Alzheimer’s disease (AD) progressively increased worldwide. The situation is aggravated by the fact that there is no the effective pharmacological therapy of AD. Photobiomodulation (PBM) is non-pharmacological approach that has shown very promising results in the therapy of AD in pilot clinical and animal studies. However, the mechanisms of therapeutic effects of PBM for AD are poorly understood. In this study on mice, we demonstrate that photodynamic effects of 5-aminolevulenic acid and laser 635 nm cause reduction of network of the meningeal lymphatic vessels (MLVs) leading to suppression of lymphatic removal of beta-amyloid (Aβ) from the right lateral ventricle and the hippocampus. Using the original protocol of PBM under electroencephalographic monitoring of wakefulness and sleep stages in non-anesthetized mice, we discover that the 7-day course of PBM during deep sleep vs. wakefulness provides better restoration of clearance of Aβ from the ventricular system of the brain and the hippocampus. Our results shed light on the mechanism of PBM and show the stimulating effects of PBM on the brain lymphatic drainage that promotes transport of Aβ via the lymphatic pathway. The effects of PBM on the brain lymphatics in sleeping brain open a new niche in the study of restorative functions of sleep as well as it is an important informative platform for the development of innovative smart sleep technologies for the therapy of AD.
Graphical Abstract
... The recommended course of treatment includes the (systemic) administration of a light-sensitive but safe drug (photosensitizer, PS), followed by the uptake of this compound and more or less selective accumulation/retention in the target cells or tissue, and the subsequent irradiation of the photosensitizer with the light of the recommended wavelength. Reactive oxygen species (ROS) are created upon quanta absorption and oxidize intracellular molecules, leading to cell death [236][237][238][239]. Fig. 7. Photo-responsive activation and inactivation approach to regulate antibacterial activity: the antibacterial effect was disabled as soon as trans -Azo-Nor was trapped by α-CD. ...
Supramolecular chemistry introduces us to the macrocyclic host cyclodextrin, which has a hydrophobic cavity. The hydrophobic cavity has a higher affinity for hydrophobic guest molecules and forms host-guest complexation with non-covalent interaction. Three significant cyclodextrin kinds are α-cyclodextrin, β cyclodextrin, and γ-cyclodextrin. The most often utilized is β cyclodextrin (β-CD). An effective weapon against bacteria that are resistant to antibiotics is cyclodextrin. Several different kinds of cyclodextrin nanocarriers (β-CD, HP-β-CD, Meth-β-CD, cationic
CD, sugar-grafted CD) are utilized to enhance the solubility, stability, dissolution, absorption, bioavailability, and permeability of the antibiotics. Cyclodextrin also improves the effectiveness
of antibiotics, antimicrobial peptides, metallic nanoparticles, and photodynamic therapy (PDT). Again, cyclodextrin nanocarriers offer slow-release properties for sustained-release formulations
where steady-state plasma antibiotic concentration is needed for an extended time. A novel strategy to combat bacterial resistance is a stimulus (pH, ROS)-responsive antibiotics released from cyclodextrin carrier. Once again, cyclodextrin traps autoinducer (AI), a crucial part of bacterial quorum sensing, and reduces virulence factors, including biofilm formation. Cyclodextrin helps to minimize MIC in particular bacterial strains, keep antibiotic concentrations above MIC in the infection site and minimize the possibility of antibiotic and biofilm resistance. Sessile bacteria trapped in biofilms are more resistant to antibiotic therapy than bacteria in a planktonic form. Cyclodextrin also involves delivering antibiotics to biofilm and resistant bacteria to combat bacterial resistance.
... In this way, antimicrobial photodynamic therapy (aPDT) has been used as a promising antibacterial technique against cariogenic pathogens, mainly in the management of deep lesions [6,[18][19][20][21]. The aPDT reaction is based on the interaction among three components: a non-toxic molecule (photosensitizer), a light source under a wavelength that is capable of exciting the photosensitizer, and local oxygen molecules [22,23]. The absorption of photons by the photosensitizer triggers the formation of free radicals and reactive oxygen species (ROS), especially singlet oxygen [24]. ...
Novel approaches for caries lesion removal and treatment have been proposed. This study evaluates the combined use of an experimental ultrasound, aPDT (antimicrobial photodynamic therapy) and bioactive glasses on the removal, decontamination and remineralization of dentin caries lesions. A biological model created with a duo species biofilm (Streptococcus mutans and Lactobacillus acidophilus) was used for the development of a caries-like lesion over the dentin for 7 days. Bovine dentin specimens (4 × 4 × 2 mm) were randomized according to the following caries removal techniques: bur (BUR) or ultrasound (ULT), decontamination (with or without aPDT) and remineralization materials (45S5 or F18 bioactive glasses). The following different groups were investigated: caries lesion (control); sound dentin (control); BUR; BUR + aPDT; ULT; ULT + aPDT; BUR + 45S5, BUR + F18; ULT + 45S5; ULT + F18; BUR + aPDT + 45S5; BUR + aPDT + F18; ULT + aPDT + 45S5; and ULT + aPDT + F18. Transverse microradiography (TMR), cross-sectional microhardness (CSH), FT-Raman spectroscopy and confocal microscopy (CLSM) were performed. A two-way ANOVA and Tukey’s test were used (α = 0.05). (3) Results: The TMR revealed a lesion depth of 213.9 ± 49.5 μm and a mineral loss of 4929.3% vol.μm. The CSH increases as a function of depth, regardless of the group (p < 0.05). Removal with BUR (24.40–63.03 KHN) has a greater CSH than ULT (20.01–47.53 KHN; p < 0.05). aPDT did not affect the CSH (p > 0.05). No difference was observed between 45S5 or F18 (p > 0.05), but a change was observed for ULT (p > 0.05). The FT-Raman shows no differences for the phosphate (p > 0.05), but a difference is observed for the carbonate and C-H bonds. The CLSM images show that aPDT effectively inactivates residual bacteria. A combination of ULT, aPDT and bioactive glasses can be a promising minimally invasive treatment.
... 3 Although hypericin is classified as a photoactive compound, its use and clinical application is limited due to a decrease in its photosensitizing activity in the presence of serum. [4][5][6][7][8][9] However, no evidence of phototoxic potential has been found in humans after oral administration of Hypericum extract. 10 Hypericin mainly accumulates in the membranes of the endoplasmic reticulum, lysosomes, Golgi apparatus and mitochondria due to its hydrophobic nature. ...
Introduction and aim. Photodynamic therapy is a complex process involving the introduction of photosensitizers into the patient’s body and irradiation of them in order to destroy the lesion, and activate the immune system. An important role in photodynamic therapy is played by photobiochemical and physical mechanisms that affect the tumor vessels and lead to the death of the damaged cell. The aim of the study is to determine the effect of photodynamic therapy with the use of Hypericin (Hyp) on the secretion of selected cytokines by colorectal cancer cells. Material and methods. Two colorectal cancer cell lines SW480 and SW620 were used in the study. Cells treated Hypericin were exposed to visible light. Then cell viability was determined by the MTT assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium. Assays were performed for control samples without hypericin and light exposure, with Hyp without light exposure, without Hyp and irradiated with light, and test samples with Hyp and light exposure. Results. In the experiment we reveal, that Hyp- photodynamic activity does not influence the secretion of cytokines. Conclusion. The obtaining results confirming the destructive effect of Hyp- PDT on the colon cancer cells, show a possibility of extending the indication for photodynamic therapy using Hyp, qualification of precancerous changes.
Photodynamic therapy (PDT) is a rapidly growing discipline that is expected to become an encouraging noninvasive therapeutic strategy for cancer treatment. In the PDT process, an efficient intersystem crossing (ISC) process for photosensitizers from the singlet excited state (S1) to the triplet excited state (T1) is critical for the formation of cytotoxic reactive oxygen species and improvement of PDT performance. Thermally activated delayed fluorescence (TADF) molecules featuring an extremely small singlet–triplet energy gap and an efficient ISC process represent an enormous breakthrough for the PDT process. Consequently, the development of advanced TADF photosensitizers has become increasingly crucial and pressing. The most recent developments in TADF photosensitizers aimed at enhancing PDT efficiency for bio‐applications are presented in this review. TADF photosensitizers with water dispersibility, targeting ability, activatable ability, and two‐photon excitation properties are highlighted. Furthermore, the future challenges and perspectives of TADF photosensitizers in PDT are proposed.
Cancer immunotherapy has made tremendous advancements in treating various malignancies. The biggest hurdle to successful immunotherapy would be the immunosuppressive tumor microenvironment (TME) and low immunogenicity of cancer cells. To make immunotherapy successful, the ‘cold’ TME must be converted to ‘hot’ immunostimulatory status to activate residual host immune responses. To this end, the immunosuppressive equilibrium in TME should be broken, and immunogenic cancer cell death ought to be induced to stimulate tumor-killing immune cells appropriately. Photodynamic therapy (PDT) is an efficient way of inducing immunogenic cell death (ICD) of cancer cells and disrupting immune-restrictive tumor tissues. PDT would trigger a chain reaction that would make the TME ‘hot’ and have ICD-induced tumor antigens presented to immune cells. In principle, the strategic combination of PDT and immunotherapy would synergize to enhance therapeutic outcomes in many intractable tumors. Novel technologies employing nanocarriers were developed to deliver photosensitizers and immunotherapeutic to TME efficiently. New-generation nanomedicines have been developed for PDT immunotherapy in recent years, which will accelerate clinical applications.
Background
Photodynamic therapy (PDT) involves the administration of a photosensitizing agent and irradiation of light at an excitation wavelength that damages tumor cells without causing significant damage to normal tissue. We developed indocyanine green (ICG)-modified liposomes in which paclitaxel (PTX) was encapsulated (ICG-Lipo-PTX). ICG-Lipo-PTX accumulates specifically in tumors due to the characteristics of the liposomes. The thermal and photodynamic effects of ICG and the local release of PTX by irradiation are expected to induce not only antitumor effects but also cancer immunity. In this study, we investigated the antitumor effects of ICG-Lipo-PTX in breast cancer.
Methods
The antitumor effects of ICG-Lipo-PTX were examined in xenograft model mice subcutaneously implanted with KPL-1 human breast cancer cells. ICG-Lipo-PTX, ICG-Lipo, or saline was administered intraperitoneally, and the fluorescence intensity was measured with a fluorescence imaging system (IVIS). Intratumor temperature, tumor volume, and necrotic area of tumor tissue were also compared. Next, we investigated the induction of cancer immunity in an allogeneic transplantation model in which BALB-MC mouse breast cancer cells were transplanted subcutaneously in the bilateral inguinal region. ICG-Lipo-PTX was administered intraperitoneally, and PDT was performed on only one side. The fluorescence intensity measured by IVIS and the bilateral tumor volumes were compared. Cytokine secretory capacity was also evaluated by ELISPOT assay using splenocytes.
Results
In the xenograft model, the fluorescence intensity and temperature during PDT were significantly higher with ICG-Lipo-PTX and ICG-Lipo in tumor areas than in nontumor areas. The fluorescence intensity in the tumor area was reduced to the same level as that in the nonirradiated area after two times of irradiation. Tumor growth was significantly reduced and the percentage of necrotic area in the tumor was higher after PDT in the ICG-Lipo-PTX group than in the other groups. In the allograft model, tumor growth on day 14 in the ICG-Lipo-PTX group was significantly suppressed not only on the PDT side but also on the non-PDT side. In addition, the secretion of interferon-γ and interleukin-2 was enhanced, whereas that of interleukin-10 was suppressed, in the ICG-Lipo-PTX group.
Conclusion
The PDT therapy with ICG-Lipo-PTX may be an effective treatment for breast cancer.
Background: Peri-implantitis, an inflammatory condition in implant tissues, requires bacterial eradication and implant surface decontamination, with aPDT as a helpful surgical adjunct. Objective:This project was designed to investigate the effect of antibiotic therapy versus aPDT, as adjuncts to conventional mechanical debridement (MD), on the peri-implant clinical and/or radiographic parameters among patients with peri-implant diseases. Methods: A comprehensive search was conducted across electronic databases, including PubMed, Scopus, and Web of Science, up to and including April 2023, without any restriction on the language and year of publication, focusing the following research question: "Does adjunctive aPDT improve the peri-implant clinical and/or radiographic parameters in treating peri-implant diseases compared to antibiotic therapy?" Statistical analysis was performed on peri-implant clinical [plaque index (PI), probing depth (PD), and bleeding on probing (BOP)] and radiographic parameters [marginal bone loss (MBL)]. The study included six randomized controlled trials and one clinical (nonrandomized) study. Results: The systematic review findings indicate that the application of aPDT as an adjunct to MD is equally effective as adjunctive antibiotic therapy in improving peri-implant clinical parameters and radiographic parameters in patients with peri-implant diseases. Only two studies were classified as having a low risk of bias (RoB), two were assessed as having an unclear RoB, and the remaining three studies were determined to have a high RoB. However, the meta-analysis results revealed no statistically significant difference in peri-implant PI, PD, and MBL scores between patients treated with adjunct aPDT or adjunct antibiotic therapy. Notably, there was a statistically significant difference favoring adjunct aPDT in peri-implant BOP values compared to the control group. Conclusions: Despite the limited number of included studies and the significant heterogeneity among them, the findings suggest that aPDT yields comparable peri-implant clinical and radiographic outcomes to adjunctive antibiotic therapy, as adjuncts to MD, for the potential treatment of peri-implant diseases.
In recent years, some microorganisms have shown resistance to conventional treatments. Considering this increase in resistant pathogens, treatment alternatives are needed to promote greater treatment efficiency. In this sense, antimicrobial photodynamic therapy (aPDT) has been an alternative treatment. This technique uses a photosensitizer that is activated by light with a specific wavelength producing reactive species, leading to the death of pathogenic microorganisms. In this study, bacteriochlorophyll derivatives such as bacteriochlorin metoxi (Bchl-M) and bacteriochlorin trizma (Bchl-T) obtained from purple bacterium (Rhodopseudomonas faecalis), were evaluated as photosensitizers in the aPDT. Photodynamic inactivation (PDI) of the microorganisms Staphylococcus aureus, Micrococcus luteus, Candida albicans and Pseudomonas aeruginosa was investigated with both bacteriochlorins (Bchl-M and Bchl-T) at different concentrations (1, 15 and 30 µM for S. aureus; 1, 15, 30, 45, 60 and 75 µM for M. luteus; 30, 60, 90, 105, 120 and 150 µM for C. albicans; and 200 µM for P. aeruginosa) and different doses of light (20 and 30 J/cm2 for S. aureus and M. luteus; 30 and 45 J/cm2 for C. albicans; and 45 J/cm2 for P. aeruginosa) to inactivate them. Both photosensitizers showed good activation against S. aureus and for M. luteus, we observed the inactivation of these microorganisms at approximately 3 log, showing to be a good photosensitizers for these microorganisms.
Topical photodynamic therapy (PDT) is widely used as an effective and well‐tolerated treatment for field change actinic keratosis, Bowen disease and superficial basal cell carcinoma. There is a strong evidence base to support its use and guidelines, which summarise the evidence and clinical utility of this therapy. There are also standards available for guidance with respect to establishing PDT services in dermatology and emphasis is placed on the availability of PDT for practitioners affiliated with a skin cancer multi‐disciplinary team. Developments in photosensitisers and light delivery, such as through the increasing application of daylight PDT, have greatly improved the tolerance, acceptability and uptake of PDT, such that this should be widely available through dermatology services. Further refinements in photosensitiser and light delivery will be expected to continue to improve PDT outcomes and the uptake of this invaluable therapeutic approach.
Photodynamic therapy is a clinical technique employing the combination of light, oxygen and a sensitising compound to induce the photochemical destruction of unwanted tissue. Light therapy has been known for some time, but it was not until the earlier part of this century that the first clinical work was performed using sensitisers and light. More recently a sensitising compound of a complex mixture of porphyrins has been tested on various cancers, and been awarded regulatory approval for its use. In this paper the synthesis and properties of some novel and easily prepared water soluble ruthenium phthalocyanine complexes are reported. One of these complexes, JM 2929, has been extensively studied and has photosensitising properties which when used in combination with light and oxygen in vitro and in vivo during photodynamic therapy displays remarkable cytotoxic effects.
Porphyrin photosensitizers are the classic drugs in clinical photodynamic therapy (PDT), but the hypoxia of tumor environment and the rapid oxygen consumption of PDT severely weaken their therapeutic effect. A recently reported water‐dependent reversible photoacidity therapy (W‐RPAT) is O2‐independence, providing a solution for the treatment of hypoxic tumors. In this work, TPP‐O‐PEG5, a porphyrin derivative with binary properties of PDT and W‐RPAT, is designed and synthesized for the first time. The nanoparticles (NPs) of TPP‐O‐PEG5 encapsulated with DSPE‐mPEG2000, an amphiphilic polymer approved by Food and Drug Administration, can simultaneously produce reactive oxygen species and H⁺ under irradiation of a 660 nm laser, and revert the H⁺ back under darkness, presenting strong phototoxicity to multiple tumor cell lines with no obvious difference between the IC50 values tested under normoxic (≈20% O2) and hypoxic (<0.5% O2) conditions. Excitingly, in vivo experiments show that the therapeutic effect of TPP‐O‐PEG5 NPs on large hypoxic tumors is better than that of NPe6, a clinical porphin PDT drug. This work provides a novel strategy for porphyrin photosensitizers to break through the limitation of hypoxic environment, and significantly improve the phototherapeutic effect on hypoxic tumors.
Organic photosensitizer with both large two‐photon absorption (σ) and efficient intersystem crossing (ISC) offers incomparable advantages in precise two‐photon photodynamic therapy. However, the current design strategy cannot achieve efficient ISC without compromising σ. Here, very efficient ISC and ultrahigh σ in organic photosensitizer (PFBT) for precise cerebrovascular two‐photon photodynamic therapy is simultaneously achieved. A hybridized local and charge‐transfer ( ¹ HLCT) excited state in PFBT, formed by incorporating benzothiadiazole into a typical polyfluorene (PF), is the key to initiating efficient ISC while bringing substantial σ enhancement (25 000 GM vs 10 000 GM) compared to PF. Mechanism studies identify that ¹ HLCT produces large spin‐orbit coupling and tiny singlet‐triplet energy gaps, together generating efficient ISC. These properties afford PFBT nanophotosensitizer a ≈2000‐fold increase in two‐photon photodynamic therapy efficiency than clinically‐used Photofrin, enabling in vivo deep‐brain cerebrovascular imaging and closure with unprecedented precision.
The authors give their experience with intraoperative photodynamic therapy used in 79 patients with Stages IIB, IIIA, B, and C breast cancer. When its procedure was being developed, the tissue distribution of alasens-induced protoporphyrin IX (PPIX) and photosens was studied in the normal tissue and tumor of the breast. The study showed the specific features of PPIX accumulation in the tumor in relation to the performance of neoadjuvant chemotherapy. Analysis of 3-year treatment results revealed no disease progression in 17 (50%) patients; 5 (14.7%) patients were diagnosed as having a locoregional recurrence; distant metastases were detected in 12 (35.5%). Intraoperative photodynamic therapy has prospects for treating locally advanced breast cancer in order to enhance intraoperative ablastics, devitalization of cancer cells of the wound surface and to prevent a local recurrence.
Злокачественные опухоли головного мозга - это заболевания с неблагоприятным прогнозом. Несмотря на применение таких современных методов лечения, как микрохирургическое удаление, лучевая терапия и химиотерапия, выживаемость этих пациентов остается низкой из-за продолженного роста опухолей. Ведется поиск новых методов лечения, способных повысить безрецидивный период и выживаемость у таких больных. Представлен анализ данных литературы по новой методике лечения данной группы больных - фотодинамической терапии.
This chapter entitled “ROS, Redox Regulation, and Anticancer Therapy” includes all redox-regulated cancer therapy events. Here in this chapter initially conventional therapy strategies, e.g., radiation, photodynamic (PD), sonodynamic (SD), chemotherapy, and natural compounds (phytochemicals) therapy events, have been introduced at experimental/preclinical, and clinical levels. Especially, recent developments in PDT/SDT with the use of nanoparticles have been highlighted. Antioxidants in cancer therapy with success and its limitations have also been discussed.
Handling chemo-resistance with combination therapy has been highlighted. Most important and exciting is the application of nanomaterials and nanoparticles in cancer therapy and drug delivery. Results of some of these applications with success have been highlighted. Seems revolutionary but until applicable in human use because of toxicity scare. Further, in this section, the importance of targeting cancer therapy (including mitochondria/metabolism targeting) has been discussed. Various immune activation strategies have also been discussed for cancer therapy. The successful application of the inhibitors of check point kinases with specific antibodies was achieved and still being improved for more efficiency. Other alternative strategies have also been introduced. Another section, redox signaling targeting as anticancer therapy, introduces using agents to inactivate various redox regulatory signaling pathways in experimental and preclinical studies. Application of miRNA as targeting therapy has also been explained.
Next, redox regulation in CSCs targeting various cancer therapy strategies, e.g., chemical inhibitors, metabolic pathway inhibitors, and immunological approaches, has been discussed in various tumor conditions in experimental, preclinical, and clinical setup. Cancer resistance due to CSCs has also been addressed. Further, induction of various PCD pathways as cancer therapy has been discussed using chemical and natural product approaches acting at the molecular events in these death pathways. The involvement of miRNA, especially in autophagy induction, has also been explored. Similarly, various strategies for managing metastasis, including detecting redox sensors and their inactivation, have been explained. The problem of adhesion-mediated drug resistance was highlighted, and immunological targeting has been discussed.
Recently, synthetic lethality approach has also been introduced with ATR and Wee1 inhibitors in clinical trials.
Further, p53 redox regulation has been exploited in cancer therapy. Apart from the pharmacological manipulation of p53, mutant LOF and GOF are in experiments with small molecule targeting to reverse therapeutic resistance. For example, inactivation of HSPs stabilizing mutant P53 approach with success is in active consideration. Two popular successful mutant p53 reactivating chemicals in clinic at advanced stage of success have been discussed. Also, developments in metabolic inactivation have been discussed.
Further, cell cycle kinase inhibitors in clinics have been discussed as anticancer therapy. Apart from the APE1 inhibitor treatments, DDR inhibitors including PARPi and others have been in clinic with success. The use of synthetic lethality is proposed.
The development of a suitable irradiation setup is essential for in vitro experiments in photodynamic therapy (PDT). While various irradiation systems have been developed for PDT, only a few offer practical and high‐quality setups for precise and reproducible results in cell culture experiments. This report introduces a cost‐effective illumination setup designed for in vitro photodynamic treatments. The setup consists of a commercially available light‐emitting diode (LED) lamp, a cooling unit, and a specially designed 3D‐printed enclosure to accommodate a multiwell plate insert. The LED lamp is versatile, supporting various irradiation wavelengths and adjustable illumination fields, ensuring consistent and reliable performance. The study evaluates the setup through various parameters, including photon flux density, illumination uniformity, photon distribution across the multiwell plate, and temperature changes during irradiation. In addition, the effectiveness of the LED‐based illumination system is tested by treating mouse mammary breast carcinoma cells (4T1) with Rose Bengal and LED irradiation at around 525 nm. The resulting IC 50 of 5.2 ± 0.9 μM and a minimum media temperature change of ca. 1.2°C indicate a highly promising LED‐based setup that offers a cost‐effective and technically feasible solution for achieving consistent, reproducible, and uniform irradiation, enhancing research capabilities and potential applications.
As the most common and aggressive type of primary brain tumor in adults, glioblastoma is estimated to end over 10,000 lives each year in the United States alone. Stand treatment for glioblastoma, including surgery followed by radiotherapy and chemotherapy (i.e., Temozolomide), has been largely unchanged since early 2000. Cancer immunotherapy has significantly shifted the paradigm of cancer management in the past decade with various degrees of success in treating many hematopoietic cancers and some solid tumors, such as melanoma and non-small cell lung cancer (NSCLC). However, little progress has been made in the field of neuro-oncology, especially in the application of immunotherapy to glioblastoma treatment. In this review, we attempted to summarize the common drug resistance mechanisms in glioblastoma from Temozolomide to immunotherapy. Our intent is not to repeat the well-known difficulty in the area of neuro-oncology, such as the blood-brain barrier, but to provide some fresh insights into the molecular mechanisms responsible for resistance by summarizing some of the most recent literature. Through this review, we also hope to share some new ideas for improving the immunotherapy outcome of glioblastoma treatment.
Understanding the thermal isomerization mechanism of azobenzene derivatives is essential to designing photoswitches with tunable half-lives. Herein, we employ quantum chemical calculations, nonadiabatic transition state theory, and photosensitized experiments to unravel the thermal Z/E isomerization of a heteroaromatic azoswitch, the phenylazo-1,3,5-trimethylpyrazole. In contrast to the parent azobenzene, we predict two pathways to be operative at room temperature. One is a conventional ground-state reaction occurring via inversion of the aryl group, and the other is a nonadiabatic process involving intersystem crossing to the lowest-lying triplet state and back to the ground state, accompanied by a torsional motion around the azo bond. Our results illustrate that the fastest reaction rate is not controlled by the mechanism involving the lowest activation energy, but the size of the spin–orbit couplings at the crossing between the singlet and the triplet potential energy surfaces is also determinant. It is therefore mandatory to consider all of the multiple reaction pathways in azoswitches in order to predict experimental half-lives.
Photodynamic therapy (PDT) is a promising therapeutic approach for anticancer and antibacterial treatment via photoinduced reactive oxygen species (ROS) generation. Photosensitizer, the most important element of PDT, plays a decisive role in PDT treatment. BODIPY dyes, as a class of well-developed fluorescent dyes, have emerged as a new class of PDT agents over the past decade owing to their versatile and remarkable properties including high molar extinction coefficients and singlet-to-triplet intersystem crossing efficiencies, tunable absorption and emission wavelengths, good ROS-generation ability, excellent photo- and chemical- stability, and easy functionalization. Several chemical approaches have been applied to tune BODIPY fluorophores into triplet photosensitizers via converting the typical fluorescence decay into a non-radiative intersystem crossing to the triplet state. However, the poor water solubility, low tumor selectivity and limited biocompatibility still hamper their biological application. Supramolecular assembly strategies have provided a promising avenue to overcome current problems of BODIPY-based molecular photosensitizers in photodynamic anticancer and antibacterial therapy. So far, numerous types of self-assembled nano-platforms have been established for construction of BODIPY-assembled supramolecular photosensitizers. This review presents the main molecular design approaches for constructing BODIPY-based photosensitizers and systematically summarizes the research progress of BODIPY-assembled supramolecular photosensitizers for PDT treatment to provide meaningful guidance for developing highly efficient BODIPY-based photosensitizers suitable for their clinical translation and application.
Topical photodynamic therapy is widely used for the treatment of superficial non‐melanoma skin cancer and dysplasia and has been shown to be at least as effective as non‐surgical standard comparators such as topical fluorouracil and cryotherapy. British and European guidelines are available for its use, and treatment is undertaken on an out‐patient basis and is generally well tolerated, with the exception of pain during irradiation in a significant proportion of patients. Optimization of treatment regimens to improve efficacy and reduce side effects have included refinements in pro‐drug development and delivery and in the methods of light delivery, in particular using reduced irradiance regimens. The use of topical photodynamic therapy (PDT) has also been applied to a wide range of other diverse skin diseases including acne vulgaris and recalcitrant viral warts and it may have a role in some of these conditions, although further studies are required. It is important that topical PDT services are widely available in dermatology, particularly to those involved in skin cancer management, through the multidisciplinary team, and that standards and clinical governance for PDT are established.
This study reports the anticancer properties of carbazole-containing phthalonitrile/phthalocyanine-modified silver nanoparticles for the first time. In this study, a new mono-substituted phthalonitrile namely 3-[9H-carbazole-9-ethoxy]phthalonitrile and its metal phthalocyanines {M = Zn, Co, and Mn(Cl)} were synthesized by template cyclotetramerization of phthalonitrile derivatives. The newly synthesized compounds were characterized using UV-vis, FT-IR, 1H NMR, 13C NMR, and mass spectroscopy. The resultant compounds were successfully linked to the surface of silver nanoparticles. The characterization of the surficial modification was carried out by applying the TEM technique. The cytotoxic activities of the studied nanoconjugates were tested against A549, DLD-1, and Wi38 cell lines by performing a (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay with/without irradiation. Although the functionalization of silver nanoparticles increased the solubility of phthalocyanines in aqueous media, the presence of phthalonitrile/phthalocyanine derivatives on the silver nanoparticles' surface improved their biological properties. All the studied biological candidates exhibited antiproliferative activities against the cell lines. The IC50 values calculated were between 6.80 and 97.99 μM against the studied cell lines in the dark. However, the IC50 values determined were between 3.11 and 88.90 μM with irradiation. The highest IC50 values obtained were 3.11 and 3.52 μM against the DLD-1 cell line for nanoconjugates 1-AgNP and 3-AgNP, respectively. The findings indicated that the compounds may be utilized as anticancer agents after further studies.
Antibiotic resistance in bacteria is one of the most serious problems that has been battled for some time. Though bacteria are somehow evolving at a rapid pace, with complex mechanisms of evading antibiotic action now and in the future, it is expected to cost society at least $ 100 trillion between 2014 and 2050. Two-dimensional (2D) transition metal carbides and nitrides (MXene), a member of the 2D family, with several unique properties and features, have considerable potential in the health, water, and food industries. The potential held by this member of the 2D family must be harnessed for applications, especially in areas where antibiotic resistance is on the rise and many strategies have proven ineffective. These properties include excellent conductivity, outstanding photothermal effect, electromagnetic interference shielding, energy storage, and conversion ability, synergistic properties, and many more that will be revealed in the future. In this review, various mechanisms of MXene in the eradication of bacteria are presented. The effect of several distinct MXene characteristics on antibacterial activity along with other biomedically related applications is further discussed. This review concludes the assessment of the current status, a description of current mechanical and functional possibilities and challenges, and a discussion of potential future possibilities to advance this research field.
Background:
Photodynamic therapy (PDT) is approved for treatment of actinic keratoses (AKs) and field-cancerisation. Pretreatment with pharmacological compounds holds potential to improve PDT efficacy, through direct interaction with PpIX formation or through an independent response, both of which may improve PDT treatment.
Objective:
To present the currently available clinical evidence of pharmacological pretreatments prior to PDT and to associate potential clinical benefits with the pharmacological mechanisms of action of the individual compounds.
Methods:
A comprehensive search on the Embase, MEDLINE, and Web of Science databases was performed.
Results:
In total, 16 studies investigated 6 pretreatment compounds: 5-fluorouracil (5-FU), diclofenac, retinoids, salicylic acid, urea, and vitamin D. Two of these, 5-FU and vitamin D, robustly increased the efficacy of PDT across multiple studies, illustrated by mean increases in clearance rates of 21.88% and 12.4%, respectively. Regarding their mechanisms, 5-FU and vitamin D both increased PpIX accumulation, while 5-FU also induced a separate anticarcinogenic response. Pretreatment with diclofenac for four weeks improved the clearance rate in one study (24.9%), administration of retinoids had a significant effect in one of two studies (16.25%), while salicylic acid and urea did not lead to improved PDT efficacy. Diclofenac and retinoids demonstrated independent cytotoxic responses, whereas salicylic acid and urea acted as penetration enhancers to increase PpIX formation.
Conclusion:
5-FU and vitamin D are well-tested, promising candidates for pharmacological pretreatment prior to PDT. Both compounds affect the haem biosynthesis, providing a target for potential pretreatment candidates.
Background:
Sporothrix brasiliensis is a pathogenic dimorphic fungus that affects humans and animals causing sporotrichosis. The treatment of this disease with conventional antifungals commonly results in therapeutic failures and resistance. Therefore, this study aimed to evaluate the in vitro effect of curcumin (CUR) mediated by photodynamic therapy (PDT) in its pure state and incorporated into pharmaceutical formulation in gel form, on the filamentous and yeast forms of S. brasiliensis.
Methods:
Cells from both forms of the fungus were treated with pure curcumin (PDT-CUR). For this, CUR concentrations ranging from 0.09 to 50 μM were incubated for 15 minutes and then irradiated with blue LED at 15 J/cm². Similarly, it was performed with PDT-CUR-gel, at lower concentration with fungistatic action. After, a qualitative and quantitative (colony forming units (CFU)) analysis of the results was performed. Additionally, reactive oxygen species (ROS) were detected by flow cytometry. Results PDT with 0.78 μM of CUR caused a significant reduction (p < 0.05) in cells of the filamentous and yeast form, 1.38 log10 and 1.18 log10, respectively, in comparison with the control. From the concentration of 1.56 μM of CUR, there was a total reduction in the number of CFU (≥ 3 log10). The PDT-CUR-gel, in relation to its base without CUR, presented a significant reduction (p < 0.05) of 0.83 log10 for the filamentous form and for the yeast form, 0.72 log10. ROS release was detected after the PDT-CUR assay, showing that this may be an important pathway of death caused by photoinactivation. Conclusion PDT-CUR has an important in vitro antifungal action against S. brasiliensis strains in both morphologies.
Glioma is one of the most serious central nervous system diseases, with high mortality and poor prognosis. Despite the continuous development of existing treatment methods, the median survival time of glioma patients is still only 15 months. The main treatment difficulties are the invasive growth of glioma and the obstruction of the blood-brain barrier (BBB) to drugs. With rapid advancements in nanotechnology, inorganic nanoparticles (INPs) have shown favourable application prospects in the diagnosis and treatment of glioma. Due to their extraordinary intrinsic features, INPs can be easily fabricated, while doping with other elements and surface modification by biological ligands can be used to enhance BBB penetration, targeted delivery and biocompatibility. Guided glioma theranostics with INPs can improve and enhance the efficacy of traditional methods such as chemotherapy, radiotherapy and gene therapy. New strategies, such as immunotherapy, photothermal and photodynamic therapy, magnetic hyperthermia therapy, and multifunctional inorganic nanoplatforms, have also been facilitated by INPs. This review emphasizes the current state of research and clinical applications of INPs, including glioma targeting and BBB penetration enhancement methods, in vivo and in vitro biocompatibility, and diagnostic and treatment strategies. As such, it provides insights for the development of novel glioma treatment strategies.
Singlet oxygen, a metastable state of normal triplet oxygen, has been identified as the cytotoxic agent that is probably responsible for in vitro inactivation of TA-3 mouse mammary carcinoma cells following incorporation of hematoporphyrin and exposure to red light. This photodynamic inactivation can be completely inhibited by intracellular 1,3-diphenylisobenzofuran. This very efficient singlet oxygen trap is not toxic to the cells nor does it absorb the light responsible for hematoporphyrin activation. We have found that the singlet oxygen-trapping product, o-dibenzoylbenzene, is formed nearly quantitatively intracellularly when both the furan and hematoporphyrin are present during illumination but not when only the furan is present during illumination. The protective effect against photodynamic inactivation of the TA-3 cells afforded by 1,3-diphenylisobenzofuran coupled with the nearly quantitative formation of the singlet oxygen-trapping product indicates that singlet oxygen is the probable agent responsible for toxicity in this system.
The photodynamic effects of sulphonated aluminium phthalocyanine (SALPC) have been compared on cultured AR4-2J cells of a pancreatic carcinoma cell line and on exocrine cells of the normal phenotype freshly isolated from the rat pancreas; a multi-channel perifusion system was used for this kinetic study in vitro. Whereas light alone or SALPC alone was without effect on either cell type, photon activation of cellularly-bound SALPC with light greater than 570 nm permeabilised the cells and caused an increase in amylase secretion from normal acinar cells but a dose-dependent inhibition (10(-7) to 10(-5) M) of amylase release from AR4-2J cells. In contrast, direct permeabilisation of the plasma membrane with digitonin, 10 micrograms ml-1, evoked a marked release of amylase from both types of cell. Elevation of [Ca2+]i by the ionophore A23187, 10(-6) M, elicited secretion of amylase from normal cells but had little effect on AR4-2J cells. Finally, it was established that the differential photodynamic effects of SALPC on amylase release were not attributable to any topographical differences in the microanatomical organisation of normal or tumour-derived cells; furthermore, the structural integrity of normal and AR4-2J cells was maintained after the photodynamic action of SALPC. It is concluded that the generation of singlet oxygen is responsible for permeabilisation of both types of cell and that photon-activated SALPC has functionally distinct effects on the constitutive secretion of amylase of tumour cells and the regulated secretory pathway of normal cells. These observations may be important in the development of drugs with a selective photodynamic action on pancreatic tumour cells.
Images
Figure 8
Photodynamic therapy (PDT) depends on the interaction of light with an administered photosensitiser to produce a local cytotoxic effect. The most widely used photosensitiser is haematoporphyrin derivative (HpD), but newer photosensitisers such as aluminium sulphonated phthalocyanine (A1SPc) are promising. HpD and A1SPc have been compared as photosensitisers for colonic PDT in the rat. Quantitative analysis showed that following injection of a standard photosensitiser dose, A1SPc produced more damage than HpD with increasing energy (fluence). Alteration of the injected dose of photosensitiser did not produce a clear difference. There was a loss of reciprocity for photosensitiser/light combinations at low injected dose (0.5 mg kg-1), both HpD and A1SPc producing no damage. Similarly at high photosensitiser dosage (25 mg kg-1) there was no quantitative difference between A1SPc and HpD. Photosensitiser photodegradation at low photosensitiser doses, and light attenuation by high tissue concentrations of A1SPc account for these findings. PDT with either agent produced the same histological damage and full thickness necrosis produced no mechanical weakening of the colon measured by the bursting pressure. The submucosal collagen was preserved and healing was by regeneration.
Images
Figure 5
Figure 6
Figure 7
Clinical photodynamic therapy consists of the systemic administration of a derivative of hematoporphyrin (Photofrin II) followed by exposure of malignant lesions to continuous visible laser irradiation. We investigated the effects of various modifications of laser light delivery on the efficacy of photodynamic therapy in controlling R3230AC mammary tumor growth. We observed a significant delay in growth (from initial to 2 times initial volume) of tumors exposed to periodic irradiation (100 mW/cm2/0.25 h, 1-h dark interval, 100 mW/cm2/0.25 h; total fluence, 180 J/cm2), compared to untreated controls or to tumors receiving continuous irradiation at the same total fluence. Other periodic light treatment regimens, consisting of 3-, 6-, or 24-hr dark intervals, delayed tumor growth but not significantly more than continuous irradiation at the same fluence. A biochemical basis was sought by comparing continuous versus periodic irradiation for effects on mitochondrial or cytosolic enzymes in vivo. Although both cytochrome c oxidase and pyruvate kinase activities were reduced dramatically during the first 24 h by continuous or periodic irradiation schemes, recovery of enzyme activity to initial levels took longer after the periodic irradiation protocol (168 h), compared to the continuous irradiation regimen (72 h). We observed a significantly greater delay in the growth of tumors exposed to 50 mW/cm2/2 h continuously, compared to controls or to tumors exposed to the same total fluence but with light delivered at 100 or 200 mW/cm2. The data presented here indicate that the efficacy of photodynamic therapy could be significantly increased by modifications in the delivery of photoradiation.
Singlet oxygen, a metastable state of normal triplet oxygen, has been identified as the cytotoxic agent that is probably responsible for in vitro inactivation of TA-3 mouse mammary carcinoma cells following incorporation of hematoporphyrin and exposure to red light. This photodynamic inactivation can be completely inhibited by intracellular 1,3-diphenylisobenzofuran. This very efficient singlet oxygen trap is not toxic to the cells nor does it absorb the light responsible for hematoporphyrin activation. We have found that the singlet oxygen-trapping product, o-dibenzoylbenzene, is formed nearly quantitatively intracellularly when both the furan and hematoporphyrin are present during illumination but not when only the furan is present during illumination. The protective effect against photodynamic inactivation of the TA-3 cells afforded by 1,3-diphenylisobenzofuran coupled with the nearly quantitative formation of the singlet oxygen-trapping product indicates that singlet oxygen is the probable agent responsible for toxicity in this system. © 1976, American Association for Cancer Research. All rights reserved.
Results of dihematoporphyrin ether (DHE) uptake and fluorescence kinetics show that the concentration in the pancreas is on the order of 40-60 μg DHE/g of tissue at an injected dose of 40 mg/kg. Previously concentrations on this order have only been found in organs of the reticuloendothelial system. Two intrapancreatic carcinoma models, one of acinar origin (rat) and one of ductal orgin (hamster), were studied. Both showed equal or higher concentrations of DHE as compared to normal pancreas when fluorescence measurements and chemical extraction procedures were performed. Photodynamic therapy (PDT) treatment of the normal pancreas and pancreatic tumors yielded atypical results. When the normal pancreas with DHE present is exposed to 630 nm light from a dye laser (75 mW/cm2, 30 min), the normal photobleaching measurable by fluorescence decay does not occur. Yet, the pancreatic tumor responds with a relatively normal fluorescence decay pattern, with hemorrhaging and a resultant loss of measurable DHE concentration. These results represent the emergence of an entirely new modality, with substantial potential for the treatment of cancer of the pancreas.
Chloro aluminium phthalocyanine tetrasulfonate is a new photosensitizer with promising properties for use in photodynamic therapy of cancer. We examined the degree of toxicity, tissue distribution, and excretion properties of this photosensitizer in normal mice. ClAlPCS was found to be a moderately toxic agent. A dose of 200 mg/kg body weight (b.w.) caused 7 percent mortality in mice kept in complete darkness and 20 percent in the ambient light exposed group. The tissue distribution, and excretion analysis demonstrated that ClAlPCS administered intravenously is eliminated from the blood stream within one hour. An immediate massive excretion of the dye was noted in urine and a delayed slow release in feces. It has been demonstrated that the dye is accumulated mainly in reticuloendothelial rich tissues. The liver is the major site of accumulation. Maximal concentration of the dye in the organs was reached after 24-48 hr. Histologic examination showed that ClAlPCS accumulated mainly in macrophage-derived and endothelial cells. The data indicate that presently recommended therapeutic doses of ClAlPCS (less than 10 mg/kg b.w.) are safe, and that angiogenic tumors would be the primary candidates for photodynamic therapy using this photosensitizer.
The photodynamic effects of bacteriochlorophyll-a (bchl-a), a sensitizer of high light absorption at long wavelengths, are greatly influenced by its rapid degradation in vivo to also photodynamically active pheophytins and chlorophylls. This can result in overall tumor destruction and direct tumor cell kill over a wide range of different wavelengths, although tumor curability is restricted to the bchl-a wavelength of 780 nm. Tumor cures are also limited to treatment conditions where light follows drug injection after a brief interval (2 hours). The major mechanism of tumor destruction appears to be vascular. Normal tissue photosensitivity induced by 780 nm light declines rapidly with time after sensitizer injection.
The photochemotherapeutic properties of several novel benzophenothiazines were evaluated
zn-vzvo in three distinct tumor types consisting of a murine sarcoma, human carcinoma, and a rat
glioma. Subcutaneous or intravenous administration of dyes to tumor bearing animals coupled
with irradiation of the tumor area with 640 nm light resulted in substantial tumor necrosis
24h post photodynamic therapy as determined by histological evaluation. Significantly, there was
minimal concurrent damage to the surrounding normal tissue. These results offer further evidence
for the potential usefulness of benzophenothiazines in the photodynamic therapy of neoplasms.
The rate constants kdobs of 1O2 consumption were measured directly in CS2 for eight 1O2 acceptors using the time-resolved technique. The values obtained agree well with the values of k1obs in toluene and benzene which were estimated indirectly from the reactivity parameter β previously determined in self-sensitized or sensitized photo-oxygenation experiments. Only the measurements of the self-sensitized photo-oxygenation of 9,10-diphenyl-anthracene (DPA) and 9,10-dimethylanthracene (DMA) in CS2 yield values of β which are consistent with a long lifetime of 1O2 of τΔ = 34 ms in this solvent. The determination of β from measurements of the self-sensitized photo-oxygenation in CS2 results in β values which are too high for the rest of the 1O2 acceptors, indicating that the lifetime of 1O2 in CS2 is strongly reduced in these experiments. The same behaviour is observed for the self-sensitized photo-oxygenation of DPA and DMA in Freon 113.
Tetramethoxystilbene undergoes reversible trans [rlhar2] cis photoisomerization (PI). The extent of PI and the fluorescence yield vary only slightly with the temperature. Photocyclization of the cis isomer leads to two 4,4′-dihydrophenanthrene-like products (DHPs), only one of which is converted into cis by visible light. Above −100 °C a thermal equilibrium exists between the two DHPs, DHP1 [rhlar2] DHP2. UV irradiation in the presence of iodine results mainly in photocyclodehydrogenation to (OCH3)4− phenanthrene. Tetrafluoro- and tetra(t-butyl)-stilbene photoisomerize to an extent decreasing on cooling, with the flourescence yield increasing concurrently. Photocyclization of tetrafluorostilbene, though less efficient than with tetramethoxy, again leads to two coloured modifications behaving as observed with tetramethoxy. In tetramethylstilbene, the corresponding DHP undergoes a two-stage decay, providing indirect evidence for the presence of two modifications. In tetra(t-butyl)-stilbene photocyclization is very inefficient.
Chinese hamster ovary cells in exponential growth were incubated with various concentrations of hematoporphyrin derivative (HpD). Cellular porphyrin content was determined after 2 h incubation at 37°C using [3H]-hematoporphyrin derivative. Photoactivation of cell-bound HpD by red light resulted in a family of survival curves with terminal slopes proportional to cellular HpD concentration. The degree of cellular lysis, assayed 1 h after illumination using a chromium-51 labeling technique, was also found to be related to cellular HpD concentration. The amount of 51Cr released increased with post-irradiation incubation to a level parallel to cell lethality as measured by colony formation. These data suggest that lysis of the cell membrane may be largely responsible for cellular inactivation following HpD photoirradiation.
— The experimental radioprotective agentsS–2-(3-aminopropylamino) ethyl phosphorothioate(WR–2721) and 3-amino-2-hydroxypropyl phosphorothioate(WR–77913) are also protective against photosensitized oxidation. They reduce porphyrin-induced photopolymerization of lens cytosol proteins in vitro, and phototoxic damage to mouse skin in vivo. The phototoxic dose modification factor (DMF) was 1.5 which is similar to that found in ionizing radiation. Part of the mechanism by which sulfhydryls afford this protection is by accelerating photobleaching of the porphyrins.
— Zinc phthalocyanines sulfonated to different degrees are tested for their ability to sensitizeV–79 Chinese hamster cells andEMT–6 mouse mammary tumors to red light. In vitro, the lower sulfonated derivatives were the most active with the exception of the poorly water-soluble monosulfonated dye. An isomeric mixture of tetrasulfonated derivatives obtained via direct sulfonation was ten times more active than the homogeneous tetrasulfo derivative prepared via the condensation of sulfophthalic acid. In vivo, the latter dye was completely inactive, whereas the remainder of the sulfonated preparations exhibited a similar structure-activity pattern as observed with theV–79 cells in vitro. The disulfonated zinc phthalocyanine showed the best tumoricidal activity in the series and also appeared to be a more efficient photosensitizer of cell inactivation and tumor cure than the aluminum or gallium complexes as well as hematoporphyrin derivative preparations. No significant differences in skin phototoxicity were observed among the various dyes.
Abstract—The distribution and elimination of [14C]PH, the radioisotopically-labeled equivalent of the mixture of porphyrins known as Photofrin II used in the photodynamic treatment of solid tumors, were determined in tumor-free and SMT-F tumor-bearing DBA/2 Ha-DD mice. Following i.p. injection, drug was absorbed from the peritoneum with a half-life of about 1 h; elimination from plasma was rapid, declining about 1.4 logs in concentration over 48 h following i.v. administration. However, some [14C]-activity was still detectable after 75 days. Normal tissues take up the drug within about 7.5 h after administration, with peak concentrations distributed as follows: liver, adrenal gland, urinary bladder > pancreas, kidney, spleen > stomach, bone, lung, heart > muscle > brain. Only skeletal muscle, brain, and skin located contralaterally to subcutaneously implanted SMT-F tumors had peak [14C]-activities lower than tumor tissue; skin overlying SMT-F tumors showed concentrations not significantly different (P > 0.3) from tumor. After 75 days all tissues examined retained some fraction of [14C]-activity, ranging from 16% for kidney to 61% for spleen, of the initial peak tissue levels. The primary route of elimination of Photofrin II was through the bile-gut pathway, with greater than 59% of the administered [14C]-activity recovered in the feces, and only about 6% in the urine, over 192 h. HPLC analyses of fecal extracts showed that mostly monomeric and other low molecular weight porphyrin components of Photofrin II were eliminated. The higher molecular weight oligomeric fractions of Photofrin II were retained in liver and spleen up to 14 days after injection.
The triplet state properties of 1,4-dihydroxy-9,10-anthraquinone (quinizarin, QNZ), 1-amino-4-hydroxy-9,10-anthraquinone (AHAQ) and 1,4-diamino-9,10-anthraquinone (DAAQ) were investigated in cyclohexane and isopropanol solutions using nanosecond laser flash photolysis. TT absorption maxima, extinction coefficients, triplet quantum yields and kinetic parameters were measured. The corresponding properties of the neutral semiquinone radicals were also determined in isopropanol. Pulse radiolysis data were used to supplement the measurements. The possibility of dimerization in solution and its effect on the photophysics of the triplet state are discussed for these quinones.
Abstract The treatment of bladder carcinoma using dihematoporphyrin ether (DHE) and laser photodynamic therapy (PDT) is described herein. Patients selected for this study have cytology- and biopsy-proven transitional cell carcinoma, no histologic evidence of muscle invasion, and negative excretory urograms.
Sixteen patients have been treated, with follow-up from 6 to 36 months. Eleven have had a complete response, and 3 a partial response in that they required re-treatment for recurrence. Two of these patients have not recurred at this time. One of the patients who recurred had tumor extension into the prostatic urethra and has been successfully re-treated (disease-free at 6 months). There was one treatment failure and 1 patient lost to follow-up.
Photosensitivity for up to 4 weeks is a known side-effect, but unexpected morbidity included a transient but significant increase in urinary frequency, urgency, and occasionally hematuria which spontaneously resolved within 3-4 weeks. Careful placement of the fiberoptic tip in the centre of the bladder, bladder distension during treatment with saline rather than water, the instillation of the minimum volume required to “smooth out” the mucosa for complete bladder photoradiation, and delivered energy of 25 J cm’or less may have prevented the more severe complications (i.e. bladder shrinkage) reported by Dougherty and Nseyo (personal communication).
We also feel that there is some early evidence that a heightened immune response (similar to intravesical BCG) may potentially play some role in explaining the efficacy of PDT in long disease-free intervals, although this is just a histologic observation at present.
It appears the PDT offers another practical treatment modality for non-invasive transitional cell carcinoma in patients refractory to standard surgical and chemotherapeutic regimens, and has been addressed by numerous other investigators such as Benson (1985) and Hisazumi (1983). We are presently recommending to our patients in these categories to undergo a course of PDT prior to relinquishing to cystectomy.
Abstract— The dependence of photodynamic therapy (PDT) on changes in drug and light doses was determined in C3H/HeJ mice bearing the RIF tumor. Measurements of tumor clonogenicity were determined 24 h after PDT over a range of drug and light doses. Representative histological samples were prepared at each of these doses. Both the drug and light dose dependence experiments showed an exponential decrease in clonogenicity after an initial shoulder region. Reciprocity of drug and light dose was established from those clonogenicity curves. Histological examination of tumors gave information concerning the localization of gross damage within tumors. Increases of light dose in PDT were shown to extend the depth of necrosis within tumors. Increases of drug dose produced enlargements in the area of necrotic spots produced by PDT
Abstract— The plasma distribution and biodistribution of benzoporphyrin derivative were examined. Two analogs of benzoporphyrin derivative were mixed with human plasma in vitro and recovered in the lipoprotein fractions upon separation by chromatography or ultracentrifugation. The majority of both analogs was recovered with high density lipoprotein. The effect of prebinding benzoporphyrin derivative to lipoproteins on the biodistribution of the drug in vivo was studied in tumor bearing DBA/2J mice. At 3, 8 and 24 h post-injection, tumor and tissue samples were excised and analyzed for benzoporphyrin derivative content. Precomplexing benzoporphyrin derivative with low density lipoprotein or high density lipoprotein led to significantly (P < 0.05) greater tumor accumulation than in aqueous solution.
Abstract— The attenuation of light in rabbit liver and striated muscle and in pig brain has been measured in the wavelength range400–800 nrn. A variable-wavelength monochromatic light source was used to illuminate the surface of the exposed tissues in situ. Optical fibers, coupled to a single photon counter, were positioned within the tissues at different depths to determine the distribution of light flux along the central axis of the light beam. The wavelength-dependence of attenuation was measured in vivo, and changes occurring in the attenuation spectra immediately post mortem were recorded. Strong absorption bands were observed around 425 nm and 550 nm in all three tissues, both in vivo and post mortem. At longer wavelengths, the attenuation decreased slowly, and no significant structure was observed. Substantial changes occurred immediately post mortem, particularly in the absorption bands. These effects are attributed mainly to de-oxygenation of blood, and changes in blood concentration in the tissues. The implications for light dosimetry in photodynamic therapy are discussed.
Abstract— The development of an extraction procedure to quantitate dihematoporphyrin ether (DHE) concentration in tissues correlated to fluorescence measurements from instrumentation developed for in vivo fluorimetry was examined. In vivo fluorometric results from mouse mammary carcinoma (SMT-F) were calibrated against results of the chemical extraction assay quantitated spectrophotometrically. Fluorescence and drug extractable levels increase in a linear fashion with injected dose. Loss of porphyrin fluorescence (photobleaching) and intra-tumoral porphyrin level has been demonstrated both in vitro (NHIK cells) and in vivo (SMT-F tumor) during illumination with light following exposure to Hpd or DHE. This process is essentially independent of porphyrin tumor level in vivo and could lead to tumor protection at very low porphyrin levels. On the other hand, this photobleaching process which occurs concurrent with cellular inactivation and tissue damage due to the photodynamic process can be exploited to protect normal tissue during photodynamic therapy (PDT) and thus greatly enhance the therapeutic ratio. This has been demonstrated in patients undergoing PDT.
The morphologic, functional, and biochemical changes produced by hematoporphyrin and light in human platelets have been characterized. by phase microscopy the cells appeared swollen and resembled signet rings; by electron microscopy they showed considerable loss of cytoplasm and their contour was smoother than normal. irradiated platelets were not aggregable by thrombin and calcium chloride, although they contained clottable protein, and were incapable of supporting clot retraction. a linear relationship was demonstrated between the per cent depletion of serotonin from irradiated platelets and the log dose of hematoporphyrin. the depletion of serotonin from these platelets was related lineraly to the log of time of exposure to light during the initial six minutes of exposure; but thereafter continued at a constant rate. the temperature of incubation influenced directly the rate of depletion of serotonin from irradiated platelets but did not influence the movement of serotonin into these platelets. atp was diminished considerably in irradiated platelets. these changes are attributable to damage to the membrane of the platelet by hematoporphyrin and light.
These studies provide additional information about the blood platelet in terms of its response to photodynamic action.
Amelioration of dihematoporphyrin ether (DHE) induced skin photosensitivity by medications either suspected or known to influence porphyrin metabolism or inflammatory response was evaluated in 357 female athymic NCR-nude mice (308 study animals, 49 controls) in 56 separate study groups. Seventy-two hours after injection with 25 mg/kg of DHE, the study animals'abdomens were irradiated with 4.125-4.25 J/cm2 of visible light. Controls were irradiated after receiving either medication, solubilizing agent, or no injection. The abdominal surface burns were examined daily and graded as extensive, partial, or no burn. Statistical comparison was made between irradiated mice injected with DHE only and irradiated mice injected with DHE and medication. Injection of medications which influenced metabolism (hydroxychloroquine, hydrochlorothiazide) produced fewer extensive (P < 0.01) but greater frequencies of partial burns than DHE controls. Medications which block histamine effect (cimetidine and/or hydroxyzine) resulted in fewer extensive (P < 0.03) and roughly equal frequencies of partial burns compared with DHE controls. Steroids (dexamethasone, methylpred-nisolone, triamcinolone) which interfere with inflammatory response resulted in similar extensive and partial burn levels. Control animals receiving only medication, solubilizing agent, or no injection had no photosensitivity and consequently showed no burns. The results from this study suggest that inhibition of histamine effect and, to a lesser extent, increased activity of porphyrin catabolic pathways may decrease skin photosensitivity associated with DHE administration.
Abstract—Two closely related strains of mouse lymphoma L5178Y cells, LY-R and LY-S, have been found to differ in their sensitivity to the cytotoxic effects of photodynamic treatment (PDT) with chloroaluminum phthalocyanine (CAPC) and red light. Strain LY-R is more sensitive to photodynamic cell killing than strain LY-S. Differences in uptake of CAPC could not account for the differences in cytotoxic effects. There was no marked difference between the two strains in the induction of single-strand breaks (which includes frank single-strand breaks and alkali-labile lesions), but substantially more DNA-protein cross-links were formed in strain LY-R by CAPC and light. Repair of single-strand breaks proceeded with similar kinetics in both strains for the first 30 min post-irradiation, suggesting that these lesions are not responsible for the differential sensitivity of the two strains to the lethal effects of photodynamic treatment. Thereafter, alkaline elution revealed the presence of increasing DNA strand breakage in strain LY-R. DNA degradation, as measured by the conversion of prelabled [14C] DNA to acid-soluble radioactivity, was more rapid and extensive in strain LY-R.
The additional optical absorption in tissue resulting from the uptake of exogenous photosensitizers increases the effective attenuation of photoactivating light. This may be significant for the irradiation of solid tumours in photodynamic therapy, since it reduces the depth or volume of tissue treated. The effect has been studied in vitro by using dihaematoporphyrin ether (DHE) and 630 nm light in tissues representing a wide range of absorption and scattering conditions. While the attenuation may be markedly changed by small concentrations of DHE in pure scattering media, tissues with significant inherent light absorption are little affected by the additional absorption of DHE at concentrations relevant to clinical photodynamic therapy. However, it is shown that for other potential photosensitizers such as the phthalocyanines, which have substantially greater absorption at the treatment wavelength than DHE, the penetration of light in tissues may be significantly reduced.
Both bacteriochlorophyll a and bacteriopheophytin a lead to a substantial photosensitized yield of singlet oxygen in several environments. The triplet quantum yields of bacteriochlorophyll a in non-deuterated solvents are somewhat lower than those of bacteriopheophytin a but the singlet oxygen quantum yields are rather similar. Both bacterial pigments react very efficiently with singlet oxygen with second-order rate constants near the diffusion-controlled limit. These results are discussed with respect to the bacterial pigment triplet energy level and the possible use of bacterial systems as “second generation” photosensitizers for photodynamic therapy of cancer.
An aqueous suspension of hydrous cuprous oxide (Cu2O·xH2O) is found to photoreduce carbonic acid selectively to methanol, but is itself sacrificed. The high yield and selectivity is attributed to strong chemisorption of carbon dioxide, highly negative flat-band potential and multielectron transfer.
The biodistribution of a new and very potent photosensitizer, benzoporphyrin derivative—monoacid, ring A (BPD-MA), was determined in normal and P815 (mastocytoma) or M1 (rhabdomyosarcoma) tumor-bearing DBA/2J mice. A dose of 80 μg Of 3H-BPD-MA was determined at 3, 24, 48, 72, 96 and 168 h post injection. The following tissues were tested: blood, brain, heart, intestine, kidney, lung, liver, muscle, skin, stomach, spleen, thymus and tumor.The biodistribution of 3H-BPD-MA in normal and tumor-bearing mice was comparable overall. 3H-BPD-MA localized in tumors better than in other tissues except kidney, liver and spleen. The tumor to tissue ratios were in the range 1.5 – 3 at 24 h post injection and increased further during the next 72 h. The highest levels of 3H-BPD-MA were observed in all tissues at 3 h post injection and decreased rapidly during the first 24 h. After 24 h the clearance from tissues was rather slow.The preliminary clearance data obtained in a group of five normal mice indicated that the majority of the injected dose (60%) cleared from the body via the bile and feces, while only about 4% cleared via kidneys and urine. Studies in which 3H-BPD-MA was extracted from tumor, kidney and liver 3 and 24 h after injection showed that, at 3 h, all the photosensitizing activity in tumor was retained. At 24 h only 39% of the activity was retained and considerably less active material was present in liver and kidney.
Four thiol-containing compounds, WR-2721, WR-149024, WR-168643 and WR-361, were compared as photoprotectors of murine feet. The protector doses were the maximal tolerated intraperitoneal doses, administered 24 h after injection of Photofrin II and 15 min before illumination with 630-nm laser light. While all four compounds were effective, only WR-2721 demonstrated a statistically significant attenuation of phototoxicity. WR-2721 was found to protect SMT-F tumors in the same mouse strain, using tumor growth delay and short-term control as endpoints. A comparison of the dose modification factors for foot and tumor responses indicated no therapeutic advantage in using WR-2721 during photodynamic treatment of these two tissues.
Bacteriochlorophyll-a (bChla), which absorbs light of 780 nm wavelength, was tested for in vivo photodynamic activity in the SMT-F and RIF transplantable mouse tumor systems. High performance liquid chromatography (HPLC) analysis of tissue extracts showed that bChla was rapidly degraded in vivo to bacteriopheophytin-a (bPheoa) and other breakdown products. These were also photodynamically active, and tumor response could be achieved over a wavelength range of 660 to 780 nm, while tumor cure was restricted to wavelengths of 755 (bPheoa) to 780 nm. A photosensitizing product absorbing at 660 nm was also present in isolated tumor cells. Photodynamic cell kill of tumor cells isolated from tumors after bChla accumulation in vivo, using 775 or 780 nm light in vitro, was exponential up to 20-40 J cm-2. Above this light dose little or no further damage could be achieved, which is an indication of the rapid photobleaching of these sensitizers. In vivo, vascular occlusion occurred readily if light treatment was delivered shortly after sensitizer administration, but was delayed if light treatment was carried out 24 h after injection. Although up to 70% of tumor cells were lethally damaged after completion of in vivo light treatment, concurrent severe vascular destruction seemed necessary for tumor cure. Normal tissue photosensitivity totally subsided within 5 days after sensitizer administration.
Porphyrin mediated photosensitization can enhance the transcription and translation of several oxidative stress genes. In this study, we report on the enhanced expression of the gene encoding for heme oxygenase in Chinese hamster fibroblasts by; (1) incubation in Photofrin II; (2) Photofrin II mediated photosensitization; and (3) photosensitization induced by Rose Bengal. Increased expression of heme oxygenase mRNA was accompanied by a concomitant increase in the synthesis of the 34 kDa heme oxygenase protein. Western blot analysis using antibody to heme oxygenase confirmed the immunoreactivity of the 34 kDa protein induced by Photofrin II and PDT. These results demonstrate that heme oxygenase can be activated by non-metalloporphyrins as well as by photosensitization associated with singlet oxygen mediated subcellular injury.
Singlet oxygen (1O2) is thought to be the cytotoxic agent in photodynamic therapy (PDT) with current photosensitizers. Direct monitoring of 1O2 concentration in vivo would be a valuable tool in studying biological response. Attempts were made to measure 1O2 IR luminescence during PDT of cell suspensions and two murine tumour models using the photosensitizers Photofrin II and aluminium chlorosulphonated phthalocyanine. Instrumentation was virtually identical to that devised by Parker in the one positive report of in vivo luminescence detection in the literature. Despite the fact that our treatments caused cell killing and tissue necrosis, we were unable to observe 1O2 emission under any conditions. We attribute this negative result to a reduction in 1O2 lifetime in the cellular environment. Quantitative calibration of our system allowed us to estimate that the singlet oxygen lifetime in tissue is less than 0.5 microsecond. Some technical improvements are suggested which would improve detector performance and perhaps make such measurements feasible.
This preliminary study was undertaken to test for the presence of urinary cytokines whose detection would provide evidence in support of the theory that photodynamic therapy (PDT) produces an immunologic response in patients treated for bladder cancer. Gamma interferon, interleukin 1-beta, interleukin 2, and tumor necrosis factor-alpha were assayed for in the urine of 4 patients treated with photodynamic therapy for bladder cancer, in 7 control patients undergoing transurethral surgical procedures, and in 5 healthy control subjects. Quantifiable concentrations of all cytokines, except gamma interferon, were measured in urine samples from the PDT patients with the highest light energies, while no urinary cytokines were found in the PDT patient who received the lowest light energy nor in any of the control subjects. These findings suggest that a local immunologic response may occur following PDT for bladder cancer.
The biodistribution and metabolism of 14C-labeled disulfonated and trisulfonated gallium phthalocyanine (Ga-PcS) was studied in radiation-induced fibrosarcoma tumor-bearing C3H mice. The [14C]Ga-PcS compounds were prepared via the condensation of [14C]phthalic acid and sulfophthalic acid in the presence of gallium chloride and characterized by their spectroscopic and chromatographic properties. The tissue concentrations of the dyes was measured by scintillation counting of the 14C and by extraction and fluorescence measurements. Elevated dye levels were found in the liver, lungs, kidneys and spleen as well as in the tumor. Lower sulfonation of Ga-PcS favored liver and spleen uptake whereas higher dye sulfonation resulted in greater kidney uptake. Both dyes showed high tumor uptake with peak concentrations exceeding those of most tissues except for the liver in the case of Ga-PcS2. The highest tumor uptake was observed with Ga-PcS3. Both dyes were slowly excreted from the body. The liver-feces pathway was favored in the case of Ga-PcS2 with high activities persisting in the liver, even after 21 days. The Ga-PcS3 was preferentially excreted via the kidney-urine pathway. High performance liquid chromatography analysis of the liver and tumor extracts of [14C]Ga-PcS3-treated animals did not reveal desulfonation of the dye. However, urine analysis showed the presence of radioactive metabolites lacking the characteristic phthalocyanine absorption.
Purpurins are modified chlorins with photodynamic properties. Their strong absorption in the red region of the visible spectrum makes them candidates for use in photodynamic cancer therapy. A series of metal derivatives of the free base purpurins have been synthesized and shown to cause tumor necrosis in transplantable tumors when exposed to visible light. In the following set of experiments, the effects of two metallo-derivatives (tin and zinc) of two purpurins, octaethylpurpurin (NT2) and etiopurpurin (ET2), and light on the N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide transplantable tumors in Fischer CDF(F344)/CrlBr rats were studied. The photodynamic activity was assessed by a short term assay using tumor dry weight 12 days after purpurin-PDT as a criterion of response. From these experiments it appears that SnET2 greater than SnNT2 greater than ZnET2 greater than ZnNT2 in photodynamic activity. SnET2 was further characterized by attempting to determine the time interval after systemic injection at which maximum therapeutic effect occurred. These studies shown that 24 h after metallopurpurin injection was the optimum time for treatment of tumors with visible light. In a final set of experiments, the effect of solar light on the skin of hairless mice injected with SnET2 was found to be much less injurious than with hematoporphyrin derivative.
Twenty-six patients with recurrent laryngeal papillomatosis received 2.5 mg/kg of Dihematoporphyrin Ether (DHE) intravenously prior to photodynamic therapy. All patients experienced some degree of photosensitivity, the only known side effect of DHE.
Reported reactions included mild erythema and inflammation (88%), swelling (58%), blistering (23%), ocular discomfort (61.5%), pruritus (38%), and skin hyperpigmentation (46%). Length of sensitivity ranged from 4–17 weeks, with an average duration of 9 weeks. No long-term debilitating sequelae were noted.
Degree of skin reaction mainly depended on how compliant the patient was in following precaution instructions. Although restrictive precautions were often difficult to strictly adhere to, most patients felt the potential benefits of the therapy far out-weighed any inconvenience.
Among the sequence of events which occur during photodynamic therapy (PDT) are depletion of oxygen and disruption of tumor blood flow. In order to more clearly understand these phenomena we have utilized transcutaneous oxygen electrodes to monitor tissue oxygen disappearance. These results provide, for the first time, non-invasive real-time information regarding the influence of light dose on tissue oxygenation during irradiation. Measurements were conducted on transplanted VX-2 skin carcinomas grown in the ears of New Zealand white rabbits. Rabbits were treated with Photofrin II and tumors were irradiated with up to 200 kJ/m2 (500 W/m2) of 630-nm light. Substantial reductions in tumor oxygen tension were observed upon administration of as little as 20 kJ/m2. For a series of brief irradiations, oxygen tension was modulated by the appearance of laser light. Tissue oxygen reversibility appeared to be dependent upon PDT dose. Long-term, irreversible tissue hypoxia was recorded in tumors for large (200 kJ/m2) fluences. These results suggest that transcutaneous oxygen tension may be useful as a general indicator of the effectiveness of PDT and as an in situ predictor of the energy required to elicit tumor damage.
Incidence of cutaneous phototoxic reactions induced by intravenous injection of Photofrin polyporphyrin was assessed in a series of 180 patients (266 injections) undergoing photodynamic therapy (PDT) at Roswell Park Cancer Institute during the period 1986-1989. In addition to the usual verbal questions regarding phototoxic reactions solicited at follow-up, forty-two patients in this group also responded to a written questionnaire designed to solicit answers to specific questions. Photofrin doses ranged from 0.5 to 2.0 mg/kg. Overall, 20-40% of patients reported some type of phototoxic response.
Oxidative degradation of cell membrane lipids in the presence of molecular oxygen, a sensitizing agent and exciting light is termed photodynamic lipid peroxidation (photoperoxidation). Like other types of lipid peroxidation, photoperoxidation is detrimental to membrane structure and function, and could play a role in many of the toxic as well as therapeutic effects of photodynamic action. Recent advances in our understanding of photoperoxidation and its biomedical implications are reviewed in this article. Specific areas of interest include (a) reaction mechanisms; (b) methods of detection and quantitation; and (c) cellular defenses (enzymatic and non-enzymatic).
The plasma distribution and biodistribution of benzoporphyrin derivative were examined. Two analogs of benzoporphyrin derivative were mixed with human plasma in vitro and recovered in the lipoprotein fractions upon separation by chromatography or ultracentrifugation. The majority of both analogs was recovered with high density lipoprotein. The effect of prebinding benzoporphyrin derivative to lipoproteins on the biodistribution of the drug in vivo was studied in tumor bearing DBA/2J mice. At 3, 8 and 24 h post-injection, tumor and tissue samples were excised and analyzed for benzoporphyrin derivative content. Precomplexing benzoporphyrin derivative with low density lipoprotein or high density lipoprotein led to significantly (P less than 0.05) greater tumor accumulation than in aqueous solution.
Photodynamic therapy (PDT) involves the treatment of tumors in the presence of sensitizer, light, and oxygen, causing energy-dependent cytotoxicity. A vascular effect that causes hemorrhagic tumor necrosis has been described with PDT, but its basis remains undefined. To investigate the possible role of tumor necrosis factor (TNF) production in the generation of such a vascular effect and/or a direct tumor effect, we treated thioglycollate-elicited murine macrophages with PDT, and we measured the possible production of TNF using the L929 assay. An energy-dependent production of TNF by macrophage treated with PDT, stimulated or unstimulated with endotoxin, was demonstrated, and TNF production was inhibited at the highest treatment energy levels. These data represent the first description of cytokine production by PDT-treated macrophages, and may serve as another mechanism of PDT cytotoxicity in vivo, either directly by TNF-mediated tumor necrosis, or indirectly by vascular effects on tumor vessels.