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Oxygen Dependence of the Photosensitizing Effect of Hematoporphyrin Derivative in NHIK 3025 Cells1
Abstract
Cells of the established line NHIK 3025 were incubated with hematoporphyrin derivative and exposed to light at different concentrations of oxygen. The efficiency of photoinactivation of the sensitized cells decreased with decreasing oxygen concentration. No photoinactivation was observed when the atmosphere above the medium overlying the cells was pure N2 gas. With 1% O2 in the atmosphere, the quantum yield of photoinactivation was reduced by 50% compared to the yield in air-saturated medium. It is hardly possible to inactivate cells in anoxic regions of a tumor by means of porphyrin sensitized photochemotherapy. In spite of this, the therapy seems to be efficient in several cases. Thus, it seems that anoxic tumor cells are inactivated in secondary reactions, probably due to breakdown of the circulatory system in the tumor.
... The general mechanism of PDT involves three primary elements, namely light with a specific wavelength, a photosensitizer (PS), and molecular oxygen [20][21][22][23] . Presently, most PDT processes occur only when oxygen is present [24][25][26] . Nonetheless, PDT can also occur in hypoxic environments even without oxygen [27] . ...
... We know that, in the absence of oxygen, type II-PDT can no longer function to produce ROS for tumor destruction. Additionally, as tumors progress rapidly, continuous oxygen consumption increases tumor hypoxia; therefore, PDT is significantly less effective against tumors [25] . Tumor hypoxia is usually classified as chronic or acute. ...
... As a non-oxygen-dependent cancer treatment, photothermal therapy (PTT) has been developed to improve antitumor effects via the use of photothermal agents to convert optical energy into thermal energy and thus cause irreversible cell damage [25,[41][42][43] . An increase in local temperature (mild heating) was shown to increase the tumor blood flow and O 2 content [44][45][46] . ...
As an emerging strategy in antitumor therapy, photodynamic therapy (PDT) has garnered significant attention in recent years for the treatment of various malignant tumors. This is due to its low side effects, superior spatial selectivity, and maximum preservation of normal tissue function. However, the hypoxic nature of tumors, continuous oxygen consumption, and microvascular damage associated with PDT treatment have impeded its development. Therefore, the focus of antitumor therapy has shifted towards enhancing the efficacy of PDT by addressing tumor hypoxia. The objective of this review is to assess and summarize the recent advancements in tumor treatment using synergistic therapy strategies (PDT+X, where X represents photothermal therapy, chemodynamic therapy, chemotherapy, immunotherapy, Photoacoustic therapy, etc .) that overcome hypoxia. Additionally, this review aims to outline the advantages and disadvantages of various collaborative methods for improving tumor hypoxia, while also discussing the challenges that lie ahead for future research.
... In this case oxygen may or may not, be involved in PDT, since the generated free radicals can be produced and act without any participation of oxygen [24,28]. Therefore, a great deal of work was done by us [29,30] and others [31][32][33][34][35][36] in the early days of PDT to elucidate the oxygen effect. It turned out that the singlet oxygen mechanism (also called type II mechanism or photodynamic action) was the main one and that PDT was inefficient in anoxia [30,[33][34][35]. ...
... Therefore, a great deal of work was done by us [29,30] and others [31][32][33][34][35][36] in the early days of PDT to elucidate the oxygen effect. It turned out that the singlet oxygen mechanism (also called type II mechanism or photodynamic action) was the main one and that PDT was inefficient in anoxia [30,[33][34][35]. However, this is only one of the routes by which oxygen influence the outcome of PDT, and there are several other routes of influence, as will be discussed in this chapter. ...
... It was, therefore, early realized that the oxygen dependency of PDT in cells was a crucial factor. Lee See et al. [36] measured this using sodium dithionite to reduce the oxygen concentration, while we did it at about the same time by flushing the cell culture with known oxygen concentration [30]. The singlet oxygen yield is constant from 100% to 20% and to 5% oxygen but is halved at 1% oxygen [30]. ...
The sections in this article areIntroductionThe Role of Oxygen in Photodynamic Therapy: 1O2 GenerationDependence of the Photosensitizing Effect on O2 ConcentrationThe Oxygenation Status in Tumors and Normal TissuesPDT-Induced Reduction of Tumor OxygenationO2 Consumption (Primary Reduction)Vascular Damage (Secondary Reactions)Photosensitizer Photobleaching (Secondary Reactions)Methods to Reduce Tumor Deoxygenation During PDTLow Fluence RatesFractionated Light ExposureOther Methods
Changes of Quantum Yields Related to Photosensitizer RelocalizationChanges of Optical Penetration Caused by Changes in O2 ConcentrationConclusion
Keywords:photodynamic therapy;oxygen;photosensitization;oxygenation;tumor deoxygenation;cancer
... to limited diffusion.Price et al. (2013) andMoan and Sommer (1985) have explored the effect of oxygen levels on PDT in monolayer cultures using various photosensitisers(232,233). The requirement of lower PDT dose for PCI also limits photochemical consumption of oxygen. ...
... to limited diffusion.Price et al. (2013) andMoan and Sommer (1985) have explored the effect of oxygen levels on PDT in monolayer cultures using various photosensitisers(232,233). The requirement of lower PDT dose for PCI also limits photochemical consumption of oxygen. ...
Photochemical internalisation (PCI) is a method for enhancing delivery of drugs such as cytotoxins to their intracellular target sites of action through the use of low dose photodynamic therapy (PDT). One of the main applications of PCI is local treatment of solid cancerous tumours. The use of three-dimensional (3D) tissue culture cancer models can provide more physiologically relevant information compared to standard monolayer culture owing to the present of an extracellular matrix. The aim of this study was to examine the effect of PDT and PCI in 3D compressed collagen cancer constructs of breast and ovarian cancer. The use of plastically compressed collagen confers near physiological densities of collagen unlike standard hydrogels. In the first set of PCI studies, a disulfonated porphyrin (TPPS2a) was used as the photosensitiser together with a cytotoxic macromolecule, a ribosome inactivating protein (saporin) to investigate the efficacy of the treatment in spheroid and non-spheroid compressed collagen 3D constructs of breast and ovarian cancer versus conventional 2D culture. Three human cell lines were investigated, a breast cancer cell line (MCF-7) and two ovarian cancer cell lines (SKOV3 and HEY). Using a range of assays including optical imaging, the treatment resulted in significant and synergistic reduction in viability of cells in the 2D and non-spheroid constructs of all 3 cell lines when measured at 48 or 96 hours post-illumination. In a further set of experiments, PCI-induced enhancement in cytotoxicity was observed when Dactinomycin was used as the cytotoxic agent. This is the first time that PCI with Dactinomycin has been investigated. In the larger spheroid constructs of ovarian cancer cells, PCI was still effective but required higher saporin and photosensitiser doses compared to 2D and non-spheroid cultures. PCI treatment was observed to induce death principally by apoptosis in the non-spheroid constructs of ovarian cancer compared to the mostly necrotic cell death caused by PDT. At low oxygen levels (1%) both PDT and PCI were significantly less effective in the constructs compared to 2D models. Using the 3D tumouroid model, where a central cancer mass is surrounded by the collagen matrix populated by fibroblasts to simulate the stroma, PCI was found to be able to both kill ovarian cancer cells within the cancer mass and inhibit their migration to the stroma. In conclusion, the use of 3D cancer models provides a useful means to assess the efficacy of PCI for the minimally invasive treatment of breast and ovarian cancer prior to in vivo studies and could help reduce the number of animals used in animal experimentation.
... -Photosensitizers excited by light can directly interact with various molecules, or interact with oxygen ; the latter is greatly favoured in most cases (Foote, 1968), and it has been shown that the presence of oxygen is an absolute requirement for photoinactivation of cells incubated with a porphyrin derivative (Moan & Sommer, 1985). The method used here to reduce oxygen did not lead to noticeable results, but according to Moan & Sommer (1985) incubation in a 1% O 2 atmosphere is sufficient for 50% of the photoinactivation effect to occur. ...
... -Photosensitizers excited by light can directly interact with various molecules, or interact with oxygen ; the latter is greatly favoured in most cases (Foote, 1968), and it has been shown that the presence of oxygen is an absolute requirement for photoinactivation of cells incubated with a porphyrin derivative (Moan & Sommer, 1985). The method used here to reduce oxygen did not lead to noticeable results, but according to Moan & Sommer (1985) incubation in a 1% O 2 atmosphere is sufficient for 50% of the photoinactivation effect to occur. It is therefore very possible that the reduction in oxygen concentration which was achieved was insufficient. ...
The acquisition of a spatial structure during embryo development involves the differentiation of cells, often according to positional information. The complexity of the molecular networks regulating differentiation and of the mechanisms generating positional information makes it necessary to study them by means of mathematical modeling. Vertebrate embryos also acquire a segmented structure during somitogenesis; this requires spatial and temporal variations in gene expression, which mathematical modeling can also help understand.
A molecular mechanism for the somitogenesis clock is proposed, which accounts for inter-cellular synchronisation, and is based on positive feedback, even though it is compatible with all experimental data interpreted as showing that the clock is based on negative feedback. Experiments proposed to test this model involve real-time clock reporters, as well as inducible systems to induce spatially-controlled perturbations.
Theoretical and experimental results have led to conflicting ideas as to how useful positional information can be established. In particular, it has been pointed out that some models of extracellular diffusion of morphogen exhibit inadequate traveling waves of receptor saturation. Two alternative (but not mutually exclusive) models are proposed, which are based on recent experimental results highlighting the roles of extracellular glycoproteins and morphogen oligomerization.
The readout of positional information is translated to a discrete set of gene expression patterns. Intriguingly, it has been observed in numerous contexts that genes regulating differentiation are initially co-expressed in progenitors despite their antagonism. We characterise conditions under which three classes of generic "master regulatory networks" can behave as a "multi-switch", directing differentiation in an all-or-none fashion to a specific cell-type chosen among more than two possible outcomes. bHLH dimerisation networks can readily display coexistence of many antagonistic factors when competition is low. Decision-making can be forced by a transient increase in competition, which could correspond to some unexplained experimental observations related to Id proteins.
... Singlet oxygen plays a crucial role in the therapeutic application of PDT. 174,175 In this process, photoactive materials generally absorb photon energy and generate reactive oxygen species (ROS). These generated ROS are used for therapeutic applications. ...
Graphitic carbon nitride (g-CN) based nanostructures are distinctive materials with unique compositional, structural, optical, and electronic properties with exceptional band structure, moderate surface area, and exceptional thermal and chemical stability. Because of these properties, g-CN based nanomaterials have shown promising applications and higher performance in the biological avenue. This review covers the state-of-the-art synthetic strategies used for the preparation of the materials, the basic structure, and a panorama of different optimization strategies leading to improved physicochemical properties responsible for the biological application. The following sections include the recent progress in the use of g-CN based nanobiomaterials for biosensors, bioimaging, photodynamic therapy, drug delivery, chemotherapy, and the antimicrobial segment. Furthermore, we have summarized the role and evaluation of biosafety and biocompatibility of the material. Finally, the unresolved issues, plausible challenges, current status, and future perspectives for the development and design of g-CN have been summarized and are expected to promote a clinical path for the medical sector and human well-being.
... However, this can be improved by coupling PDT to optical fibers or intraluminal/interstitial settled multi light sources [17]. Moreover, hypoxia, the major barrier of PDT efficiency and the main reason for PDT resistance, can be counteracted by PS dosimetry [18][19][20][21]. In addition to the improvement of irradiation light equipment and optimization of oxygen ratio in the tumor, there is a need for further optimization of PSs. ...
Photodynamic therapy (PDT), in which a light source is used in combination with a photosensitizer to induce local cell death, has shown great promise in therapeutically targeting primary tumors with negligible toxicity and minimal invasiveness. However, numerous studies have shown that noninvasive PDT alone is not sufficient to completely ablate tumors in deep tissues, due to its inherent shortcomings. Therefore, depending on the characteristics and type of tumor, PDT can be combined with surgery, radiotherapy, immunomodulators, chemotherapy, and/or targeted therapy, preferably in a patient-tailored manner. Nanoparticles are attractive delivery vehicles that can overcome the shortcomings of traditional photosensitizers, as well as enable the codelivery of multiple therapeutic drugs in a spatiotemporally controlled manner. Nanotechnology-based combination strategies have provided inspiration to improve the anticancer effects of PDT. Here, we briefly introduce the mechanism of PDT and summarize the photosensitizers that have been tested preclinically for various cancer types and clinically approved for cancer treatment. Moreover, we discuss the current challenges facing the combination of PDT and multiple cancer treatment options, and we highlight the opportunities of nanoparticle-based PDT in cancer therapies.
... The non-eliminated phylloerythrin accumulates in the systemic circulation and, under the action of sunlight it absorbs certain wavelengths of ultraviolet rays and becomes active [29]. Activated, its molecules react with oxygen causing free radicals with cytotoxic action [15] that can result cellular lesions, intense inflammatory response, and eventually death [21,29]. ...
Background: Although the etiology of hepatogenous photosensitization has not yet been fully elucidated, it is known
that hepatotoxic substances (saponins) present in grasses of the genus Brachiaria spp. are responsible for intoxication of
ruminants and horses, causing great economic losses in the whole world. Since this grass is the source of food for the herd
in Brazil, and other countries of the world, the aim of this paper is to describe the epidemiological, clinical, laboratory and
anatomopathological aspects of a steer with this disease.
Case: A 3-year-old Nellore steer was referred to veterinary care at a property in Bahia, with a 3-week history of swelling,
loss of cutaneous tissue in the ear and scrotum region, and dry faeces. The animal was raised in pasture with Brachiaria
decumbens along with five animals of different age and sex; however, it was the only one to present symptoms. Although
the animal had been treated at the farm, there was no clinical improvement. On clinical examination, the steer was apathetic
with jaundiced mucous membranes, nasal and ocular discharge, epiphora, and ulcers on the labial and gum commissure.
The steer had leukocytosis with neutrophilia, anemia, and hyperfibrinogemia. The body condition score (BCS) was 2 (BCS
ranges from 1 to 5), and the skin lesions observed were bedsores, necrosis and scabs in several regions. The increase in liver
enzymes (GGT, AST) indicated hepatic impairment, suggesting a case of hepatogenous photosensitization. The therapeutic
protocol instituted was enteral hydration, electrolyte replacement, topical application of ointment in the injured areas. In
addition, it was recommended to maintain the animal in the shade, supply of good quality grass, and a new clinical evaluation
in seven days. On new examination, it was observed that there was no satisfactory clinical improvement of the animal, and
persistence of laboratory changes. Despite the poor prognosis, treatment was continued for another month with the same
recommendations. However, in view of the severe clinical condition and unfavorable prognosis, the animal was submitted
euthanasia. Necropsy revealed extensive areas of bedsores, erythema, severe jaundice in the mucous membranes, eyeballs
and opaque corneas. The liver had an enlarged volume with bulging edges and a greenish color. The kidneys had a pale
brownish color, with an irregular and mottled subcapsular surface, with blackened and depressed spots. Histologically, the
cytoplasm of the hepatocytes was finely vacuolated, sometimes refringent and with an abundant presence of bile pigment. It
was also observed in the middle of the liver parenchyma, multiple foci of accumulation of macrophages filled with vacuoles
of different sizes containing saponins and crystals of saponins inside bile ducts. Furthermore, it was possible to observe
hypertrophy and hyperplasia of Kupffer cells, disarrangement of hepatocytes with individual necrosis of hepatocytes.
Discussion: The diagnosis of hepatogenous photosensitization was based on history, clinical, laboratory and anatomopathological findings. Serum biochemistry was important to measure hepatic impairment and possible secondary lesions,
which were confirmed by the necropsy. Although hepatogenous photosensitization is less common in adult cattle, it must
be considered in the differential diagnosis of skin lesions, reduced appetite, and jaundice. Since it was a sporadic case,
individual predisposition is probably a preponderant factor.
... As another component, oxygen is very important for PDT efficacy. Studies showed that: a) performing PDT under anoxic conditions has no effect on tumor growth rate; b) response of a skin-implanted tumor in mice to PDT with Photofrin ® requires an oxygen tension of about 5 kPa, while the PDT efficacy is reduced by 50% at 1 kPa.59, 60 The oxygen-dependent nature of PDT limits its effective use against hypoxic tumors. ...
A series of water-soluble anthrancene (Ant) endoperoxides (EPOs) have been synthesized and their oxygen release kinetics were investigated. From Singlet Oxygen Sensor Green (SOSG) assay and trapping of singlet oxygen with fufuryl alcohol, we could derive that there was more than 39% singlet oxygen release during the thermolyses of our new Ant EPOs in water at 37 °C, which is significantly higher than the known compound EPO 18 that was used to promote cell survival under anoxic conditions. Therefore, applying new EPOs to rescue anoxic tissues was not evaluated. Instead, the activity of new Ant EPOs against a wide range of bacteria (M. smegmatis, M. tuberculosis, E. coli, S. aureus, S. epidermis) was investigated. Some pyridinium modified Ant EPOs displayed good antibacterial activity, mainly based on the membrane binding and disruption by pyridinium moiety and toxic singlet oxygen release in situ from EPO moiety. By adjusting the charge distance and substitution patterns, the oxygen release kinetics as well as antibacterial activity can be tuned. These results showed that the combination of bis-pyridinium quaternary ammonium compounds (QACs) with EPO moiety is a good strategy for the development of new antibiotics.
A couple of trehalose-photosensizer conjugates were synthesized and their photo-toxicity against mycobacteria was investigated. Most of these trehalose-photosensizer conjugates displayed better activity than non-conjugated photosensizers (including protoporphyrin, BODIPY and methylene blue) against M. smegmatis and M. abscessus. The activity of some trehalose-photosensizer conjugates is comparable to some clinical drugs, such as rifampicin, ciprofloxacin, amikacin and SQ109. Applying trehalose led to accumulation of photosensizers in the mycomembrane, and upon irradiation, pathogens can be selectively destroyed. This strategy is promising to treat mycobacteria-caused infections and trehalose-photosensitizer conjugates represent an exciting new class of antimycobacterial agents.
... The yield of singlet oxygen is most likely linked to the efficacy of PDT with photosensitizers that localize in tumor tissue (1O2) in the tumor [3]. The yield of 1 O 2 , in turn, depending on the tissue's oxygen concentration [4]. Some tumors may have oxygen concentrations that are very low for PDT to be effective [5]. ...
Abstract— The term “cancer” covers more than a hundred
diseases that assign one trait: the abandoned growth of
abnormal cells that abolish healthy tissues and have the
potential to spread outside its site of origin. When a malignant
tumor originates in the breast, it is called breast cancer. Gold
nano particles display potential for both the imaging and cure
of breast cancer. From a logistical standpoint, most breast
tumors arise near the skin's surface, where they may possibly
be extracted and handled despite the NIR laser's minimal
tissue penetration.Photodynamic therapy is a fairly new
treatment option for both cancer and non-cancer diseases that
involves the activation of certain dyes with light in the
existence of molecular oxygen (photosensitizers) that the target
tissue has absorbed in a very selective manner. The
combination of hyperthermia and photoelectric dose
improvement of radiation therapy could be effectively treat
superficial positioned inflammatory breast
cancersorrecurrenceinthepost-mastectomychestwall.Inthis
review paper, the novel work in photothermal therapy is
debated, as well as the combined effects of gold nanoparticles
and photothermal heating on breast cancer cells are studied in
details.
... Such effects might be because of PDT cytotoxicity and PDT damage to tumor vasculature (Star et al., 1986;Chen et al., 1996). The therapeutic action of PDT depends on the efficient generation of singlet oxygen from the triplet oxygen ( 3 O 2 ); therefore, tissue oxygenation seems to be extremely important for the efficacy of PDT (Lee See et al., 1984;Moan and Sommer, 1985). In conclusion, the choice of optimal combinations of PS dose, light sources, and treatment parameters are very important in order to achieve successful results in PDT (Henderson et al., 2006). ...
Photodynamic therapy (PDT) mostly relies on the generation of singlet oxygen, via the excitation of a photosensitizer, so that target tumor cells can be destroyed. PDT can be applied in the settings of several malignant diseases. In fact, the earliest preclinical applications date back to 1900’s. Dougherty reported the treatment of skin tumors by PDT in 1978. Several further studies around 1980 demonstrated the effectiveness of PDT. Thus, the technique has attracted the attention of numerous researchers since then. Hematoporphyrin derivative received the FDA approval as a clinical application of PDT in 1995. We have indeed witnessed a considerable progress in the field over the last century. Given the fact that PDT has a favorable adverse event profile and can enhance anti-tumor immune responses as well as demonstrating minimally invasive characteristics, it is disappointing that PDT is not broadly utilized in the clinical setting for the treatment of malignant and/or non-malignant diseases. Several issues still hinder the development of PDT, such as those related with light, tissue oxygenation and inherent properties of the photosensitizers. Various photosensitizers have been designed/synthesized in order to overcome the limitations. In this Review, we provide a general overview of the mechanisms of action in terms of PDT in cancer, including the effects on immune system and vasculature as well as mechanisms related with tumor cell destruction. We will also briefly mention the application of PDT for non-malignant diseases. The current limitations of PDT utilization in cancer will be reviewed, since identifying problems associated with design/synthesis of photosensitizers as well as application of light and tissue oxygenation might pave the way for more effective PDT approaches. Furthermore, novel promising approaches to improve outcome in PDT such as selectivity, bioengineering, subcellular/organelle targeting, etc. will also be discussed in detail, since the potential of pioneering and exceptional approaches that aim to overcome the limitations and reveal the full potential of PDT in terms of clinical translation are undoubtedly exciting. A better understanding of novel concepts in the field (e.g. enhanced, two-stage, fractional PDT) will most likely prove to be very useful for pursuing and improving effective PDT strategies.
... PpIX production is maximal at pH 7.4 and could be negatively affected by the acidic environment in which tumor cells reside [66]. Additionally, the photosensitizing effect of porphyrin derivatives in cancer cells has been shown to be oxygen dependent, an effect associated with reduced photodynamic therapy efficacy in hypoxic conditions [80,81]. Hypoxia is a hallmark of the tumor microenvironment for low-and high-grade gliomas alike. ...
Simple Summary
5-aminolevulinic acid (5-ALA) is a medication that produces fluorescence in certain cancers, which enables surgeons to visualize tumor margins during surgery. Gliomas are brain tumors that can be difficult to fully resect due to their infiltrative nature. In this review we explored what is known about the mechanism of 5-ALA, recent discoveries that increase our understanding of that mechanism, and potential targets to increase fluorescence in lower grade gliomas.
Abstract
5-aminolevulinic acid (5-ALA) is a porphyrin precursor in the heme synthesis pathway. When supplied exogenously, certain cancers consume 5-ALA and convert it to the fluorogenic metabolite protoporphyrin IX (PpIX), causing tumor-specific tissue fluorescence. Preoperative administration of 5-ALA is used to aid neurosurgical resection of high-grade gliomas such as glioblastoma, allowing for increased extent of resection and progression free survival for these patients. A subset of gliomas, especially low-grade tumors, do not accumulate PpIX intracellularly or readily fluoresce upon 5-ALA administration, making gross total resection difficult to achieve in diffuse lesions. We review existing literature on 5-ALA metabolism and PpIX accumulation to explore potential mechanisms of 5-ALA-induced glioma tissue fluorescence. Targeting the heme synthesis pathway and understanding its dysregulation in malignant tissues could aid the development of adjunct therapies to increase intraoperative fluorescence after 5-ALA treatment.
... producing hydroxyl radicals and superoxide anions or with oxygen (type II reaction) to produce a highly reactive singlet oxygen species which has a lifespan measured in microseconds (Foote, 1968). Oxygen has been shown to be important both in vitro (Moan and Sommer, 1985) and in vivo (Bown et al, 1986). ...
Atherosclerosis is the commonest aetiology in deaths arising from cardiovascular disease. It is characterised by the build up of an intraluminal plaque leading to arterial stenosis. Balloon angioplasty offers a minimally invasive method of dilating such stenoses in both peripheral and coronary arteries. However, despite very favourable immediate results, 15-40% of arteries restenose within 3-6 months following angioplasty with obvious clinical and resource implications. Restenosis is caused by a combination of neointimal hyperplasia (NIH) and negative geometric remodelling, the combined effect of which results in luminal narrowing. The aim of this thesis was to investigate a method of inhibiting restenosis using photodynamic therapy (PDT). PDT involves the interaction of light of a specific wavelength with a pre-administered photosensitiser to produce cell death by oxygen-dependent cytotoxic mediators. Experimental project Preliminary studies established the pharmacokinetics of the chosen photosensitiser 5-aminolaevulinic acid (ALA) in a swine model. From these experiments the optimum drug-light interval was calculated and in a second study, PDT was applied to normal porcine iliac and coronary arteries using an endovascular light source. Depletion of medial vascular smooth muscle cells (VSMC) was seen at 3 and 14 days and was found to be partially dependent on the drug-light interval. Finally, iliac and coronary arteries were balloon injured and then treated with PDT or sham illumination. Histomorphometric studies following harvest at 28 days showed less NIH and less negative remodelling in the group treated with PDT. Clinical project A clinical pilot study of angioplasty with adjuvant PDT was commenced. Patients deemed to be at high risk of restenosis underwent femoral angioplasty followed by endovascular PDT and were followed up by duplex and digital subtraction angiography at 6 months. The results of this small study would suggest that PDT is successful in inhibiting restenosis, but this now needs to be confirmed in a randomised controlled trial.
... This approach is dominating in humans due to the high level of oxygen [29]. However, as the oxygen runs out, the mechanism of type I begins to prevail [3], and in general, photodynamic toxicity is reduced [30][31][32][33]. Because hypoxia is a characteristic of most solid cancerous tumors [34], we also investigated the significance of oxygen in PDT utilizing ZnTPPS 4 and ZnPcS 2 . ...
Photodynamic therapy (PDT) is gradually becoming an alternative method in the treatment of several diseases. Here, we investigated the role of oxygen in photodynamically treated cervical cancer cells (HeLa). The effect of PDT on HeLa cells was assessed by exposing cultured cells to disulphonated zinc phthalocyanine (ZnPcS2) and tetrasulphonated zinc tetraphenylporphyrin (ZnTPPS4). Fluorescence microscopy revealed their different localizations within the cells. ZnTPPS4 seems to be mostly limited to the cytosol and lysosomes, whereas ZnPcS2 is most likely predominantly attached to membrane structures, including plasmalemma and the mitochondrial membrane. Phototoxicity assays of PDT-treated cells carried out under different partial pressures of oxygen showed dose-dependent responses. Interestingly, ZnPcS2 was also photodynamically effective at a minimal level of oxygen, under a nitrogen atmosphere. On the other hand, hyperbaric oxygenation did not lead to a higher PDT efficiency of either photosensitizer. Although both photosensitizers can induce a significant drop in mitochondrial membrane potential, ZnPcS2 has a markedly higher effect on mitochondrial respiration that was completely blocked after two short light cycles. In conclusion, our observations suggest that PDT can be effective even in hypoxic conditions if a suitable sensitizer is chosen, such as ZnPcS2, which can inhibit mitochondrial respiration.
... En solution aqueuse, sa durée de vie est d'environ 5µs et son rayon de diffusion est estimé à 5 nm [6,7]. L'efficacité de la PTD est dépendante de la présence en quantité suffisante (>2%) d'oxygène dans les tissus [8,9]. Les cellules cancéreuses ont une tendance à l'hypoxie. ...
L’objectif de cette thèse était de mettre au point une analyse critique de vecteurs polymères utilisés pour la thérapie photodynamique (PDT) et de faire le lien avec l’efficacité thérapeutique observée. Pour cela, une analyse complète des vecteurs a été réalisée par des techniques classiques comme la diffusion dynamique de la lumière ou la microscopie électronique, mais aussi grâce au fractionnement flux-force, technique peu utilisée jusqu’à présent dans le domaine des auto-assemblages polymères. Dans un deuxième temps, les auto-assemblages ont été utilisés comme vecteurs d’un photosensibilisateur, le Phéophorbide a, et l’efficacité thérapeutique évaluée en travaillant sur culture cellulaire 2D et 3D de lignées HCT116 (cancer du colon) ou FaDu (cancer tête et cou). Différents vecteurs polymères simples ont tout d’abord été examinés, à savoir des micelles ou des polymersomes à base de copolymères diblocs amphiphiles comme le poly(oxyde d’éthylène-b--caprolactone), le poly(oxyde d’éthylène-b-lactide) ou le poly(oxyde d’éthylène-b-styrène). Ceci a permis d’obtenir des vecteurs présentant des tailles et des morphologies variables. Les résultats en PDT ont montré des comportements différents et une meilleure efficacité en 3D pour les systèmes à base de PEO-PDLLA. La technique de fractionnement flux-force asymétrique (AsFlFFF) a particulièrement été utilisée pour ces vecteurs afin de démontrer la pureté des auto-assemblages. Les connaissances acquises dans cette première partie ont permis de caractériser des vecteurs faits à base de mélanges d’auto-assemblages micelles/vésicules. Ceux-ci ont révélé des phénomènes d’antagonisme ou de synergie dans l’efficacité en PDT, démontrant l’existence de processus complexes au niveau de la réponse cellulaire.Des auto-assemblages figés par réticulation ont aussi été développés, caractérisés et examinés en PDT. Ils se sont avérés extrêmement intéressants pour la PDT sur les cultures cellulaires en 3D, démontrant une efficacité accrue comparée aux systèmes simples. La comparaison de ces résultats avec ceux obtenus en culture 2D pour les mêmes objets a de plus permis de mettre en évidence la différence entre ces deux modèles biologiques. Enfin, des auto-assemblages à base de complexes poly-ioniques ont aussi été formés et caractérisés. Le fractionnement flux-force s’est là encore avéré efficace, mais a nécessité l’utilisation d’une injection spéciale par Frit-inlet. Leur efficacité en PDT s’est avérée faible.
... The evidence for the requirement of oxygen for PDT cytotoxicity has been widely investigated. Many groups have shown that in anoxic conditions, PDT effects are suppressed (Gomer & Razum, 1984;Lee See et al., 1984;Moan & Sommer, 1985). ...
Photodynamic therapy (PDT) involves the activation of a previously administered photosensitising agent by light resulting in the formation of cytotoxic oxygen species capable of tissue necrosis. The aim of this thesis was to evaluate the role of PDT in the treatment of tumours of the head and neck region both preclinically and clinically. Preclinical studies were carried out on a rabbit model to determine the effect of PDT on normal bone using tumouricidal doses of drug and light. Minimal effects were seen on normal bone using three photosensitisers; Photofrin , aminolaevulinic acid (ALA) and meta tetrahydroxyphenyl chlorin (mTHPC). PDT is an attractive option for the management of nasopharyngeal carcinoma (NPC). Initial pharmacokinetic and PDT studies were carried out on normal rabbits using two photosensitisers, mTHPC and phthalocyanine (AlS2Pc) prior to embarking on clinical therapy. The concern with PDT in the nasopharynx is the close proximity of the brain. Both sensitisers were taken up in the nasopharyngeal mucosa, with no detectable levels in the brain. Using light doses that produced mucosal necrosis in the nasopharynx, no neurological deficit Nor histological damage was observed. Light transmission studies through the skull base confirmed that little light reached the brain from the nasopharynx. The clinical role of PDT was evaluated in patients with oral cancer and dysplasia, using three photosensitisers; Photofrin, ALA and mTHPC. Encouraging results were observed in patients with field cancerization following Photofrin PDT, although the prolonged skin photosensitivity was a major disadvantage. ALA PDT was found to be very effective in superficial epithelial disease (dysplasia). For early invasive disease the best results were seen using mTHPC. Seventeen out of twenty-one T1 and T2 cancers showed complete local responses along with much lower light doses than required for other photosensitisers. With an appropriate choice of photosensitiser, PDT is developing an important role in the management of premalignant and early invasive disease of the mouth.
... Certainly in tissue culture where oxygen is present at higher saturation than in vivo, a considerable reduction in oxygen level is needed to inhibit cell death after PDT. Moan and Sommer (1985) found that if the oxygen tension in the cell culture medium was reduced below 10 mmHg, then there was a 50% inhibition of photodynamic cell kill. This is of some concern in the treatment of larger tumours which are likely to contain a hypoxic cell fraction, unlikely to be sensitive to the direct effects of PDT. ...
Lasers techniques are able to produce precise and sometimes unique tissue effects. These promise an improvement over the conventional techniques for treating both superficial and early muscle invasive bladder cancer. Photodynamic Therapy (PDT) is an experimental treatment that shows great promise for treating superficial bladder cancer, especially resistant carcinoma in situ (Cis). Some clinical studies though have reported serious side effects, mainly in producing an irreversible functional impairment in many bladders due to fibrosis. This thesis presents a study of the effect of changes in dosimetry variables on the normal rat bladder using a new photosensitiser, aluminium chlorosulphonated phthalocyanine. The uptake of this drug into the different layers of the bladder wall has also been investigated using sensitive fluorescence microscopy techniques. The maximum concentration gradient of photosensitiser between the superficial and the deep layers of the bladder wall was reached after 24 h following administration and was increased by the photobleaching observed at low sensitiser concentrations. Morphological and functional changes (bladder capacity and compliance) were also studied and it was found that if PDT damage was restricted to the superficial layers of the bladder, the resulting functional disturbance was less severe and recovered more fully than when the muscle layers were also involved. At low concentrations of photo-sensitiser a selective, superficial necrosis was achieved across a wide range of light doses. If these experimental results can be achieved in clinical practice then PDT should provide an effective and bladder preserving treatment for Cis without the complications that have been seen previously. The possible role of the flashlamp pulsed-dye laser for PDT was studied using cultured human bladder carcinoma cells (MGH-U1) sensitised with dihaematoporphyrin ether. It was found that this clinical laser was of a comparable efficacy to the more complex systems currently used for PDT. The morphology of the coagulation produced by the neodymium:YAG laser on the pig bladder has been compared with conventional electrocautery. A marked qualitative difference was seen between these two modalities in that the laser produced a more even coagulation with little disruption of the tissue architecture. A major attraction for urologists is that, in conjunction with flexible cystoscopy, superficial bladder tumours may be laser coagulated on an outpatient basis using only topical urethral anaesthesia. A study of 33 patients with recurrent tumours treated in this way shows the convenience and economy of this technique though no reduction in the incidence of recurrences was seen after laser therapy.
... We investigated if the lack of enhanced cytotoxicity of sunitinib-PCI ("light after") could be explained by ROS mediated photodamage of sunitinib. Singlet oxygen ( 1 O 2 ) is considered as the most important ROS formed during photochemical treatment as applied in this work [23,24]. The short half-life (<0.04 µs) and diffusion distance (10-20 nm) of singlet oxygen in cellular membranes [25] implicate that TPCS 2a should be in close intracellular vicinity of sunitinib in order to induce photochemical damage of the TKI. ...
Lysosomal accumulation of sunitinib has been suggested as an underlying mechanism of resistance. Here, we investigated if photochemical internalization (PCI), a technology for cytosolic release of drugs entrapped in endosomes and lysosomes, would activate lysosomal sequestered sunitinib. By super-resolution fluorescence microscopy, sunitinib was found to accumulate in the membrane of endo/lysosomal compartments together with the photosensitizer disulfonated tetraphenylchlorin (TPCS2a). Furthermore, the treatment effect was potentiated by PCI in the human HT-29 and the mouse CT26.WT colon cancer cell lines. The cytotoxic outcome of sunitinib-PCI was, however, highly dependent on the treatment protocol. Thus, neoadjuvant PCI inhibited lysosomal accumulation of sunitinib. PCI also inhibited lysosomal sequestering of sunitinib in HT29/SR cells with acquired sunitinib resistance, but did not reverse the resistance. The mechanism of acquired sunitinib resistance in HT29/SR cells was therefore not related to lysosomal sequestering. Sunitinib-PCI was further evaluated on HT-29 xenografts in athymic mice, but was found to induce only a minor effect on tumor growth delay. In immunocompetent mice sunitinib-PCI enhanced areas of treatment-induced necrosis compared to the monotherapy groups. However, the tumor growth was not delayed, and decreased infiltration of CD3-positive T cells was indicated as a possible mechanism behind the failed overall response.
... The efficacy of the treatment is dependent on many factors that dynamically interact during treatment. Ground state oxygen is needed for formation of singlet oxygen, which means that tissue oxygenation strongly influences treatment efficacy [2]. Illumination with high fluence rates can deplete oxygen levels in both tumor and normal tissue, limiting efficacy [3,4]. ...
Targeted photodynamic therapy (PDT) has the potential to improve the therapeutic effect of PDT due to significantly better tumor responses and less normal tissue damage. Here we investigated if the efficacy of epidermal growth factor receptor (EGFR) targeted PDT using cetuximab-IRDye700DX is fluence rate dependent. Cell survival after treatment with different fluence rates was investigated in three cell lines. Singlet oxygen formation was investigated using the singlet oxygen quencher sodium azide and singlet oxygen sensor green (SOSG). The long-term response (to 90 days) of solid OSC-19-luc2-cGFP tumors in mice was determined after illumination with 20, 50, or 150 mW·cm−2. Reflectance and fluorescence spectroscopy were used to monitor therapy. Singlet oxygen was formed during illumination as shown by the increase in SOSG fluorescence and the decreased response in the presence of sodium azide. Significantly more cell death and more cures were observed after reducing the fluence rate from 150 mW·cm−2 to 20 mW·cm−2 both in-vitro and in-vivo. Photobleaching of IRDye700DX increased with lower fluence rates and correlated with efficacy. The response in EGFR targeted PDT is strongly dependent on fluence rate used. The effectiveness of targeted PDT is, like PDT, dependent on the generation of singlet oxygen and thus the availability of intracellular oxygen.
... The singlet oxygen ( 1 O 2 ) produced by the reaction of photoexcited porphyrin molecules with oxygen molecules in tumor cells 43 involves the oxygen dependence of the photosensitizing effect of photosensitizers. Moan and Sommer 44 reported the quantum yield of sodium porfimer to be about 0.9 relative unit at oxygen concentrations of 0.07 mM. However, the study was performed on sodium porfimer at lower concentrations than those used for clinical applications, and the drug dosages given are far in excess of the levels required for maximal singlet oxygen generation. ...
The goal of our study was to determine the susceptibility of different pancreatic cell lines to clinically applicable photodynamic therapy (PDT). The efficacy of PDT of two different commercially available photosensitizers, verteporfin and sodium porfimer, was compared using a panel of four different pancreatic cancer cell lines, PANC-1, BxPC-3, CAPAN-2, and MIA PaCa-2, and an immortalized non-neoplastic pancreatic ductal epithelium cell line, HPNE. The minimum effective concentrations and dose-dependent curves of verteporfin and sodium porfimer on PANC-1 were determined. Since pancreatic cancer is known to have significant stromal components, the effect of PDT on stromal cells was also assessed. To mimic tumor-stroma interaction, a co-culture of primary human fibroblasts or human pancreatic stellate cell (HPSCs) line with PANC-1 was used to test verteporfin-PDT-mediated cell death of PANC-1. Two cytokines (TNF-α and IL-1β) were used for stimulation of primary fibroblasts (derived from human esophageal biopsies) or HPSCs. The increased expression of smooth muscle actin (α-SMA) confirmed the activation of fibroblasts or HPSC upon treatment with TNF-α and IL-1β. Cell death assays showed that both sodium porfimer- and verteporfin-mediated PDT-induced cell death in a dose-dependent manner. However, verteporfin-PDT treatment had a greater efficiency with 60 × lower concentration than sodium porfimer-PDT in the PANC-1 incubated with stimulated fibroblasts or HPSC. Moreover, activation of stromal cells did not affect the treatment of the pancreatic cancer cell lines, suggesting that the effects of PDT are independent of the inflammatory microenvironment found in this two-dimensional culture model of cancers.
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... Effects of oxygenation of levels on PDT been explored previously in 2D culture with different photosensitisers [63,64] and our 2D data showing partial inhibition at 1% hypoxia are in agreement with the data shown in these studies. However, in 2D culture oxygen can freely diffuse from the surrounding medium to counteract photochemical consumption effects and replenish intracellular oxygen levels, and much smaller oxygen concentrations are needed to fully abrogate PDT in 2D culture, as can be achieved using chemical methods of oxygen depletion [65,66]. ...
Photochemical internalisation (PCI) is a method for enhancing delivery of drugs to their intracellular target sites of action. In this study we investigated the efficacy of PCI using a porphyrin photosensitiser and a cytotoxic agent on spheroid and non-spheroid compressed collagen 3D constructs of ovarian cancer versus conventional 2D culture. The therapeutic responses of two human carcinoma cell lines (SKOV3 and HEY) were compared using a range of assays including optical imaging. The treatment was shown to be effective in non-spheroid constructs of both cell lines causing a significant and synergistic reduction in cell viability measured at 48 or 96 hours post-illumination. In the larger spheroid constructs, PCI was still effective but required higher saporin and photosensitiser doses. Moreover, in contrast to the 2D and non-spheroid experiments, where comparable efficacy was found for the two cell lines, HEY spheroid constructs were found to be more susceptible to PCI and a lower dose of saporin could be used. PCI treatment was observed to induce death principally by apoptosis in the 3D constructs compared to the mostly necrotic cell death caused by PDT. At low oxygen levels (1%) both PDT and PCI were significantly less effective in the constructs.
... 2 Nonradiative dissipation of the excitation energy of both PS and singlet oxygen reduces PDT efficacy. Besides, malignant tissues commonly have a deficit of free molecular oxygen 3,4 which makes PDT treatment less effective. These facts stimulate the search for oxygen independent mechanisms of photo-chemotherapy based on the formation of non-excited and active species, such as free radicals. ...
The cytotoxicity of Nitrofurantoin (NFT) in the dark and after light exposure (UVA irradiation, λ = 385 nm) is evaluated in murine melanoma B16F10 cells. NFT induces both cell proliferation and inhibition of the cell viability. The dominance of one or the other effect depends on the drug concentration, incubation time (tinc) and irradiation dose. The uptake of NFT in these cells, as well as its photocytotoxicity, reaches the saturation after 24 hours of incubation. The mechanism of cell death in the dark is associated with the enzymatic release of nitric oxide (NO). The increase of NFT cytotoxicity under light irradiation is associated with the increase of NO concentration due to photorelease. NO photorelease by NFT in solution was confirmed by chemiluminescence, while NO formation in cells was confirmed by fluorescence microscopy using DAF-2DA, a specific indicator of NO in living cells. The NFT does not enter nuclei, distributing preferentially in the cell cytoplasm, as shown by fluorescence microscopy.
... Another reason is the importance of oxygen for the therapeutic effect of for instance radiotherapy and certain chemotherapies [103,104]. In PDT, the formation of singlet oxygen needs ground state oxygen, therefore tissue oxygenation heavily influences PDT efficacy [105,106]. Some PSs precursors such as aminolevulinic acid (ALA), are more effectively metabolized to the active PS, protoporphyrin IX (PpIX), in oxygen rich environments [107]. ...
Photodynamic therapy (PDT) is a clinically approved cancer therapy, based on a photochemical reaction between a light activatable molecule or photosensitizer, light, and molecular oxygen. When these three harmless components are present together, reactive oxygen species are formed. These can directly damage cells and/or vasculature, and induce inflammatory and immune responses. PDT is a two-stage procedure, which starts with photosensitizer administration followed by a locally directed light exposure, with the aim of confined tumor destruction. Since its regulatory approval, over 30 years ago, PDT has been the subject of numerous studies and has proven to be an effective form of cancer therapy. This review provides an overview of the clinical trials conducted over the last 10 years, illustrating how PDT is applied in the clinic today. Furthermore, examples from ongoing clinical trials and the most recent preclinical studies are presented, to show the directions, in which PDT is headed, in the near and distant future. Despite the clinical success reported, PDT is still currently underutilized in the clinic. We also discuss the factors that hamper the exploration of this effective therapy and what should be changed to render it a more effective and more widely available option for patients.
... With most photosensitizers under investigation, in addition to amounts of photosensitizer and light, PDT effi-cacy is also oxygen dependent. [222][223][224][225][226][227][228][229] It is generally accepted that the oxygen dependence is based on the requirement to form the active species, singlet oxygen from interaction of the excited photosensitizer with molecular oxygen dissolved in the tissue. This concept was mostly based on extrapolation from solution chemistry because the detection of singlet oxygen in vivo was not possible until very recently. ...
... The tumor is irradiated with light matching the absorption of PpIX, which initiates the photochemical reaction, in which reactive singlet oxygen is formed. The singlet oxygen is generally believed to be one of the key factors for the desired therapeutic effect of PDT (Weishaupt et al 1976;Moan and Sommer 1985). Consequently, the presence of appropriate concentration of sensitizer, light matching the absorption of the sensitizer and molecular oxygen in the tissue, is crucial for the effi ciency of PDT. ...
The number of non-melanoma skin cancers is increasing worldwide, and so also the demand for effective treatment modalities. Topical photodynamic therapy (PDT) using aminolaevulinic acid or its methyl ester has recently become good treatment options for actinic keratosis and basal cell carcinoma; especielly when treating large areas and areas with field cancerization. The cure rates are usually good, and the cosmetic outcomes excellent. The only major side effect reported is the pain experienced by the patients during treatment. This review covers the fundamental aspects of topical PDT and its application for treatment of actinic keratosis and basal cell carcinoma. Both potentials and limitations will be reviewed, as well as some recent development within the field.
... It has been reported that low oxygen concentration can reduce the 1 O 2 yield and compromise the PDT efficacy. [50][51][52] Alternatively, studies on PDT of human tumor xenogras with meta-tetrahydroxyphenylchlorin have shown that photochemical process leading to radical formation can work better under hypoxic condition. 52 Several recent studies also showed that PS which act via type I photochemical mechanism induce better PDT efficacy under hypoxia. ...
We report the synthesis of a new iodinated Chlorin p6 copper complex (ICp6–Cu) and its efficacy for photodynamic treatment (PDT) of cancer cells. The metal complex is obtained by reacting Chlorin p6 (Cp6) with copper iodide (CuI). The complex formation results in a shift in the Q absorption band of Cp6 from 663 nm to 634 nm and X-ray fluorescence of the complex showed the presence of both copper and iodine. FTIR and EPR spectroscopy suggests that the copper is attached to Cp6 at the two adjacent carboxylic groups. Studies on the photochemical generation of singlet oxygen (1O2) and other reactive oxygen species (ROS) using fluorescence probes revealed that ICp6–Cu acts predominantly through the type I process. PDT of oral cancer cells with ICp6–Cu (10 μM, 3 h) and red light (630 ± 20 nm, ∼12 J cm−2) led to ∼90% phototoxicity. Furthermore, in contrast to Cp6, the phototoxicity induced by ICp6–Cu is not significantly affected under hypoxic conditions.
... It involves the administration of a photosensitizing agent and its subsequent activation by light. This reaction is strongly dependent on oxygen concentration (120)(121)(122)(123). Cell killing by PDT appears to be complete at normal oxygen levels and above, but decreases as the oxygen concentration drops below 5% (123). ...
Poor microenvironmental conditions are a characteristic feature of solid tumors. Such conditions occur because the tumor vascular supply, which develops from the normal host vasculature by the process of angiogenesis, is generally inadequate in meeting the oxygen and nutrient demands of the growing tumor mass. Regions of low oxygenation (hypoxia) is believed to be the most critical deficiency, since it has been well documented to play a significant role in influencing the response to conventional radiation and chemotherapy treatments, as well as influencing malignant progression in terms of aggressive growth and recurrence of the primary tumor and its metastatic spread. As a result, significant emphasis has been placed on finding clinically applicable approaches to identify those tumors that contain hypoxia and realistic methods to target this hypoxia. However, most studies consider hypoxia as a single entity, yet we now know that it is multifactorial. Furthermore, hypoxia is often associated with other microenvironmental parameters, such as elevated interstitial fluid pressure, glycolysis, low pH, and reduced bioenergetic status, and these can also influence the effects of hypoxia. Here, we review the various aspects of hypoxia, but also discuss the role of the other microenvironmental parameters associated with hypoxia.
... c.1 O 2 in PDT.1 O 2 is the main cytotoxic agent in PDT53,56,60,61 . There exist two low-lying excited states of 1 Δ g and 1 g 62, 63 . ...
Heteroatom-substituted dioxetanes are one subclass of dioxetanes that have at least one heteroatom (such as O, S, N) at its two carbons of dioxetane structures. These are readily formed from the [2+2] cycloaddition reaction of heteroatom-substituted alkenes and singlet oxygen (1O2). Due to their unique characteristics, such as chemiluminescence and spontaneous cleavage, heteroatom-substituted dioxetanes have been used for a number of biomedical applications, for example biomedical analyses and light-controlled drug release. A number of review papers and book chapters have been published for the biomedical analyses of chemiluminescence. However, no comprehensive review or book chapter for the applications to light-controlled drug release have yet been published, although there have been very significant and interesting advances in the field in the last couple of years. In this chapter, we focus mainly on a new and exciting application of dioxetanes for light-controlled drug release. In the latter part of this section, we also introduce briefly another new interesting application of dioxetane chemistry for hydrogen peroxide (H2O2) imaging.
Keywords: heteroatom-substitued dioxetanes; visible and near infrared; drug delivery; photodynamic;singlet oxygen;alkenes; biomedical applications; drug release; light-controlled; hydrogen peroxide imaging
Many IONPs-based nanoplatforms have been created to use for successful cancer treatment. Both traditional chemotherapies based on drug delivery and alternative treatment techniques like photothermal therapy have made use of these nanoplatforms.
Photodynamic therapy (PDT) elicits cell death, vascular damage, or/and anti-tumor host immune response upon activating the administered photosensitive drug by an appropriate light source. Because PDT is heavily dependent on tissue oxygen (O2) in essence, the concentration-dependent impact of O2 on tailoring cellular response to PDT remains an in-depth investigation. As a multifaceted modality, optimal combinations of photosensitizer (PS) concentration, light dose, and O2 delivery are critical to achieve ideal therapeutic outcomes. We herein present a fully integrated all-in-one device for the in vitro assessment of PDT efficacy synchronizing the quantitative control of three PDT disciplines simultaneously, aiming at 1) identifying the influence of varying gaseous microenvironments on PDT; and 2) determining the contribution of each PDT factor and estimating the strength of their synergic effect. The gas-gradient-generating unit for contactless headspace O2 delivery and spatial light control filtering layer in our device could either work as a stand-alone module or combine to screen a range of experimental PDT parameters. By sweeping a total of 128 conditions over four 5-aminolevulinic acid (5-ALA) concentrations, four light dosages, and eight O2 levels in one single experiment, we determined the main effects of the three key PDT agents and highlighted the interactive effect between 5-ALA and light after full-factorial statistical analysis. Our device is not only a versatile tool for predicting PDT efficacy during the translational study but also provides valuable multidimensional information for the interrelation between key PDT factors, which may expedite clinical PDT dosimetry and furnish new insights for the fundamental understanding of photobiological processes.
Over the past 30 years, photodynamic therapy (PDT) has shown great development. In the clinical setting the few approved molecules belong almost exclusively to the porphyrin family; but in the scientific field, in recent years many researchers have been interested in other families of photosensitizers, among which BODIPY has shown particular interest. BODIPY is the acronym for 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene, and is a family of molecules well-known for their properties in the field of imaging. In order for these molecules to be used in PDT, a structural modification is necessary which involves the introduction of heavy atoms, such as bromine and iodine, in the beta positions of the pyrrole ring; this change favors the intersystem crossing, and increases the 1O2 yield. This mini review focused on a series of structural changes made to BODIPYs to further increase 1O2 production and bioavailability by improving cell targeting or photoactivity efficiency.
In vivo data are rare but essential for establishing the clinical potential of ruthenium-based photoactivated chemotherapy (PACT) compounds, a new family of phototherapeutic drugs that are activated via ligand photosubstitution. Here a novel trisheteroleptic ruthenium complex [Ru(dpp)(bpy)(mtmp)](PF6)2 ([2](PF6)2, dpp = 4,7-diphenyl-1,10-phenanthroline, bpy = 2,2’-bipyridine, mtmp = 2-methylthiomethylpyridine) was synthesized and its light-activated anticancer properties were validated in cancer cell monolayers, 3D tumor spheroids, and in embryonic zebrafish cancer models. Upon green light irradiation, the non-toxic mtmp ligand is selectively cleaved off, thereby releasing a phototoxic ruthenium-based photoproduct capable notably of binding to nuclear DNA and triggering DNA damage and apoptosis within 24-48 h. In vitro, fifteen minutes of green light irradiation (21 mW.cm-2, 19 J.cm-2, 520 nm) of this compound were sufficient to generate high phototherapeutic indexes (PI) in a range of cancer cell lines including lung (A549), prostate (PC3Pro4), conjunctival melanoma (CRMM1, CRMM2, CM2005.1) and uveal melanoma (OMM1, OMM2.5, Mel270) cancer cell lines. The therapeutic potential of [2](PF6)2 was further evaluated in zebrafish embryo ectopic (PC3Pro4) or orthotopic (CRMM1, CRMM2) tumour models. The ectopic model consisted of red fluorescent PC3Pro4-mCherry cells injected intravenously (IV) into zebrafish, that formed perivascular metastatic lesions at the posterior ventral end of caudal hematopoietic tissue (CHT). By contrast, in the orthotopic model, CRMM1- and CRMM2-mCherry cells were injected behind the eye where they developed metastatic lesions. The maximally-tolerated dose (MTD) of [2](PF6)2 was first determined for three different modes of compound administration: i) incubating the fish in prodrug-containing water (WA); ii) injecting the prodrug intravenously (IV) into the fish; or iii) injecting the prodrug retro-orbitally (RO) into the fish. To test the anticancer efficiency of [2](PF6)2, the embryos were treated 24 h after engraftment at the MTD. Optimally, four consecutive PACT treatments were performed on engrafted embryos using 60 min drug-to-light intervals and 90 min green light irradiation (21 mW.cm-2, 114 J.cm-2, 520 nm). Most importantly, this PACT protocol was not toxic to the zebrafish. In the ectopic prostate tumour models, where [2](PF6)2 showed the highest photoindex in vitro (PI >31), the PACT treatment did not significantly diminish the formation of metastatic lesions, while in both conjunctival melanoma orthotopic tumour models, where [2](PF6)2 showed more modest photoindexes (PI ~ 9), retro-orbitally administered PACT treatment significantly inhibited growth of the engrafted cells. Overall, this study represents the first demonstration in zebrafish cancer models of the clinical potential of ruthenium-based PACT, here against conjunctival melanoma.
Objective:
The macroscopic singlet oxygen (MSO) model for quantifying the light-induced singlet oxygen (1O2) always contain a set of nonlinear dynamic equations and therefore are generally difficult to be applied. This work was devoted to analyze and simplify this dynamic model.
Methods:
Firstly, the nonlinearity of the MSO model was analyzed. The conditions, under which it can be simplified to a linear one, were derived. Secondly, in the case of ample triplet oxygen concentration, a closed-form exact solution of the 1O2 model was further derived, in a nonlinear algebraic form with only four parameters that can be easily fitted to experimental data. Finally, in vitro experiments of antifungal light therapies were conducted, where the fungi, Candida albicans, were irradiated respectively by the 385, 405, 415, and 450nm wavelength light. The singlet oxygen concentration levels in the fungi were measured, and then used to fit the developed models.
Results:
The parameters of the closed-form exact solution were estimated from both the simulated and the measured experimental data. Based on this model, a functional relationship between the photon energy, fluence rate and singlet oxygen concentration was also established. The fitting accuracy of this model to the data was satisfactory, which therefore demonstrates the effectiveness of the proposed modeling techniques.
Conclusion:
The results from simulating the proposed closed-form model indicate that the photon energy within the range of either 2.7-2.8 eV or 3.0-3.2 eV (388-413nm or 443-459nm in wavelength) is more effective in generating singlet oxygen in the fungi studied in this work.
Significance:
It is the first attempt of applying control theory to analyze the photochemical reaction dynamics of light therapies in terms of their nonlinearity. The proposed modeling techniques also offer opportunities for determining the light dosages in treating fungal infection diseases, especially those on the surface tissues of human body.
In recent years, there has been a steady increase in patients with Hepatocellular Carcinoma (HCC) mainly in the north of France. Despite a large number of therapeutic options, HCC has a high cancer-related mortality. Hence there is a need to develop novel therapeutic strategies for HCC treatment which could augment the efficacy of existing options and at the same time provide longer tumor free survival for the patients.Photodynamic Therapy (PDT) is a local anti-tumoral modality relying on systemic administration of a non-toxic dye, called Photosensitizer (PS), and subsequent illumination by light of appropriate wavelength and energy to elicit tumor cell death. Initially used for treatment of dematological ailments, PDT has shown motivating results as a possible anti-tumoral therapy in last few decades.Using 5-Aminolevulinic acid (5-ALA), the US-FDA approved oral pro-drug of Protoporphyrin IX, the actual PS, we investigated the in-vitro impact of PDT over HCC cell lines, along with patient tumoral hepatocytes, healthy donor liver myofibroblasts and human immune system. At last, we validated our results on an in-vivo model of HCC. The overall aim is to establish 5-ALA PDT as an adjuvant to partial hepatectomy through intra-operative procedures.When the HCC cell lines were treated with varying 5-ALA concentration and light doses, we observed a dose-dependent decrease of cellular viability. We also observed varying sensitivity for 5-ALA PDT between the three HCC cell lines used (HuH7, Hep3B, HepG2), highlighting the role of p53 for underlying cell death mechanism. Thereafter, an IC50 dose for each of the cell line was obtained which induced decreased cellular proliferation and increased cell death with respect to non-treated control. These results confirm that 5-ALA PDT induce cell death to the HCC cell lines.Furthermore, in order to validate the ex vivo efficacy of 5- ALA-PDT we studied the impact of this therapy on tumor hepatocytes from four patients with HCC, showing that cell viability decreased continuously up to 4 times, from day 3 after illumination, compared to the untreated control. In addition, we have studied the safety of 5-ALA-PDT in liver myofibroblasts from healthy donors. Our results show that 5-ALA-PDT does not induce any change in terms of viability and proliferation of healthy myofibroblasts and that the levels of expression of the mRNA of the markers of fibrosis, namely collagen-1, HSP47, αSMA, TIMP1 and MMP2 are not modified. In addition, no modulation of the levels of collagen secretion was observed.Most interestingly, when we cultured human activated Peripheral Blood Mononuclear Cells (PBMCs), with conditioned media obtained from 5-ALA PDT treated HCC cell lines, we observed increased cellular proliferation with respect to non-treated control. This highlights clonogenic expansion and possible anti-tumor immune response activation by 5-ALA PDT. This conditioned media have further inhibit the proliferation of respective cancer cell lines, reflecting secretion of anti-proliferation factors by cells due to PDT.At last, our in-vivo results demonstrated that PpIX has higher accumulation in the tumor with respect to non-tumoral tissues and a decrease in the rate of tumor growth for humanized SCID mice treated by 5-ALA PDT, with respect to Non-Treated control group.To date, no other study has evaluated the impact of 5-ALA PDT on primary patient and healthy donor samples. We are also the first to assess the impact of 5-ALA PDT treated conditioned media on PBMCs and cancer cell line proliferation. Our study strengthens the notion of the application of intra-operative 5-ALA PDT for treatment of HCC patients. Further studies will aim to understand the role of p53 in the cell death mechanism, identify the immune population activated by PDT, evaluate the efficacy of the therapy in a humanized SCID mice model and establish a standard treatment protocol to be utilized in a clinical set-up.
Cancer is a long-known incurable disease, and the medical use of cisplatin has been a significant discovery. However, the side-effects of cisplatin necessitate the development of new and improved drug. Therefore, in this study, we focused on the photoactivatable Pt(IV) compounds Pt[(X1)(X2)(Y1)(Y2)(N3)2], which have a completely novel mechanism of action. Pt(IV) can efficiently overcome the side-effects of cisplatin and other drugs. Here, we have demonstrated, summarized and discussed the effects and mechanism of these compounds. Compared to the relevant articles in the literature, we have provided a more detailed introduction and a made comprehensive classification of these compounds. We believe that our results can effectively provide a reference for the development of these drugs.
Cancer of the pancreas is the fifth commonest cause of cancer death and even with treatment, 80-90% of patients die within a year of diagnosis. Photodynamic therapy (PDT) is a non-thermal technique for inducing tissue necrosis. Cytotoxic oxygen species are produced from the interaction between light of a specific wavelength and a photosensitising agent in an oxygenated tissue. Experimental studies using the photosensitisers mTHPC and ALA have shown PDT to have a substantial therapeutic potential for the treatment of pancreatic cancer. mTHPC gave the largest volume of necrosis around treatment sites but clinically causes skin photosensitisation for up to a month. ALA photosensitivity only lasts 1-2 days, but clinical studies show that at the maximum tolerated dose (60mg/kg) the effect is too superficial. The aims of this thesis were: 1. To assess the safety and feasibility of interstitial PDT using mTHPC for the treatment of inoperable pancreatic cancer. To undertake animal studies to investigate a method of enhancing ALA PDT by the addition of the hydroxypyridinone iron chelator, CP94, to slow down the conversion of PPIX (the photoactive derivative of ALA) to haem. The pilot clinical study on 16 patients with localised but inoperable pancreatic cancers (2-6cm in diameter) showed that PDT could produce tumour necrosis with no treatment related mortality and a median survival of 12.5 months. Major complications included bleeding and duodenal stenosis but these were manageable. Experiments on hamsters with cancer transplanted into their pancreas showed significantly higher tissue levels of PPIX and significantly larger volumes of PDT produced tumour necrosis in those given ALA and CP94 compared with ALA alone. This thesis has shown that clinical, interstitial PDT with mTHPC for pancreatic cancer is technically feasible and could produce some survival benefit. This should now be tested in a randomised, controlled trial. The animal experiments showed that adding an iron chelator may enhance ALA PDT. This could now be tested clinically. These encouraging results justify further studies of the possible role of PDT in the management of cancer of the pancreas.
Melanoma is the rarest skin tumor. Nevertheless, it is related with an extremely high mortality rate and abundant therapeutic difficulties concerning the current strategies applied in its treatment and remission, including those of pharmacological and surgical nature. Because of this, new treatments are required to allow a higher efficacy than the previously demonstrated therapies.
The present project emerges as an attempt to solve this problem through the framework of previous studies in this particular combination of pathology and photodynamic therapy.
Therefore, merging the previous experience of the present research group in this field of knowledge, four new photosensitizer molecules, chemically of the chlorine type were studied, NAMP 103A, NAMP 103B, NAMP 263A, NAMP 263B.
The studies performed were only achieved in vitro, with the cytotoxicity of each of the photosensitizers first being ascertained as well as the concentration which in each case inhibited cell proliferation by 50 %. To ascertain the selectivity of each photosensitizer to melanoma cells, each molecule was applied to HFF1 human fibroblast cell line (non-tumor cell line) and results showed that there was no significant difference. Through the application of these compounds, the tumor cells demonstrated significant decreases in their metabolic activities as well as viability, being such facts dependent on the concentration of each photosensitizer and it has been shown that these occurrences are a consequence of the type of cell death, cell cycle phase, variation of mitochondrial homeostasis, and generation of reactive oxygen species at intracellular level.
From the obtained results, it is possible to infer that photodynamic therapy constitutes a
therapeutic opportunity whose effects may be differentiating with respect to the therapeutic results in the mentioned pathology.
Background
Ablative fractional photothermolysis (aFP) using a CO2 laser generates multiple small diameter tissue lesions within the irradiation field. aFP is commonly used for a wide variety of dermatological indications, including treatment of photodamaged skin and dyschromia, drug delivery and modification of scars due to acne, surgical procedures and burns. In this study we explore the utility of aFP for treating oncological indications, including induction of local tumor regression and inducing anti-tumor immunity, which is in marked contrast to current indications of aFP.
Methodology/Principal findings
We used a fractional CO2 laser to treat a tumor established by BALB/c colon carcinoma cell line (CT26.CL25), which expressed a tumor antigen, beta-galactosidase (beta-gal). aFP treated tumors grew significantly slower as compared to untreated controls. Complete remission after a single aFP treatment was observed in 47% of the mice. All survival mice from the tumor inoculation rejected re-inoculation of the CT26.CL25 colon carcinoma cells and moreover 80% of the survival mice rejected CT26 wild type colon carcinoma cells, which are parental cells of CT26.CL25 cells. Histologic section of the FP-treated tumors showed infiltrating neutrophil in the tumor early after aFP treatment. Flow cytometric analysis of tumor-infiltrating lymphocytes showed aFP treatment abrogated the increase in regulatory T lymphocyte (Treg), which suppresses anti-tumor immunity and elicited the expansion of epitope-specific CD8⁺ T lymphocytes, which were required to mediate the tumor-suppressing effect of aFP.
Conclusion
We have demonstrated that aFP is able to induce a systemic anti-tumor adaptive immunity preventing tumor recurrence in a murine colon carcinoma in a mouse model. This study demonstrates a potential role of aFP treatments in oncology and further studies should be performed.
Background:
The most fundamental problem in cancer biology research is to understand the mechanisms of cancer cell resistance to oncological therapies. Literature reports emphasize the important role of adhesion molecules: intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 (ICAM-1 and VCAM-1) in cancer progression and resistance to treatment. Photodynamic therapy (PDT) could become the component of a personalized approach to colorectal cancer, therefore we examined the effects of ALA (δ-aminolevulinic) acid PDT in normoxia and under cobalt chloride (CoCl2)-induced hypoxia on ICAM-1 and VCAM-1 secretion by colorectal cancer cells.
Methods:
Human colorectal cancer cells of different malignant potential SW480 and SW620 were used in the experiment. Cell lines were treated ALA, in order to achieve conditions comparable to in vivo hypoxia, CoCl2 was added, then cells were irradiated both in normoxia and in hypoxia-like conditions. Cell viability was assessed using the LDH and MTT assays and apoptosis. ICAM-1 and VCAM-1 concentrations were determined with the Bio - Plex ProTM Assay and System.
Results:
The experiment revealed that ALA PDT under normoxia and CoCl2-induced hypoxia had no significant effect on ICAM-1 and VCAM-1-dependent adhesion of colorectal cancer cells. The secretion of ICAM-1 by SW480 ell line was more pronounced compared to ICAM-1 secretion by SW620 cells.
Conclusion:
Determination of tumor marker levels and especially adhesion molecules involved in metastatic spread is necessary. Our experiment reveals, that ALA PDT in normoxia and CoCl2-induced hypoxia has no effect on adhesion molecules secretion by colon cancer cells in vitro.
Most nonviral gene transfection vectors deliver transfecting DNA into cells through the endocytic pathway (1,2). Poor escape from endocytic vesicles in many cases constitutes a major barrier for delivery of a functional gene, since the endocytosed transfecting DNA is unable to reach the cytosol and be further transported to the nucleus, but rather is trapped in endocytic vesicles and finally degraded in lysosomes (3). Therefore, the development of endosome-disruptive strategies is of great importance for the further progress of gene transfection. We have developed a new technology, termed photochemical internalization (PCI), to achieve light-inducible permeabilization of endocytic vesicles (4–8). The technology is based on photochemical reactions initiated by photosensitizers localized in endocytic vesicles and inducing rupture of these vesicles upon light exposure (4). This leads to the release of endocytosed macromolecules such as transfecting DNA from endocytic vesicles into the cytosol (Fig. 1). As a light-dependent treatment, PCI-mediated transfection (photochemical transfection) allows the possibility of directing the gene delivery to a desired site, e.g., achieving tumor-specific expression of a therapeutic gene in gene therapy in vivo. Fig. 1. Principle of photochemical internalization (PCI). I, endocytosis of the pho-tosensitizer (S) and the transfecting gene (G); II, localization of the photosensitizer and the transgene in the same endocytic vesicles; III, rupture of endosomal membrane upon light exposure and subsequent release of the transfecting gene into the cytosol.
Die Prüfung der Ersetzbarkeit von blitzlampengepumpten Farbstofflasern mit Pulslängen in der Größenordnung von µs im Vergleich zu kontinuierlich arbeitenden Lasern für die PDT erscheint aufgrund folgender Punkte sinnvoll:
1.
Es kann mit geringerem technischen Aufwand eine höhere Leistung erreicht werden (ca.10 W im Gegensatz zu ca. 3 W mit dem Argon-Laser gepumpten Farbstofflaser).
2.
Durch den wesentlich höheren physikalischen Wirkungsgrad ist der Energieverbrauch deutlich geringer (ca. 0,1% im Gegensatz zu 0,01%).
3.
Die einfachere Technik ermöglicht eine leichtere Handhabung und geringere Kosten bei der Anschaffung und Wartung (z.B. ist nur ein Laser zu justieren).
4.
In einigen Kliniken befinden sich blitzlampengepumpte Farbstoff-Laser bereits in der klinischen Anwendung (z.B. Lithotripsie und Angioplastie); der zusätzliche Einsatz für die PDT wäre also z.B. in der Urologie für die Behandlung multifokal wachsender Harnblasenkarzinome denkbar.
The evaluation of a new modality of cancer treatment requires quantitative measurements of tumor- as well as normal tissue response. Since photoradiation therapy (PDT) also involves injection of a photosensitizinq druq, it is important to obtain information about the pharmacoloqy of the druq: blood transport, retention in different tissues, rates and pathways of excretion etc.
Die photodynamische Therapie (PDT) ist ein neues Verfahren zur lokalen Behandlung von Karzinomen. Dem Patienten wird ein Photosensibilisator verabreicht, der bei fehlendem Lichteinfall nicht toxisch ist. Der Photosensibilisator reichert sich bis zu einem gewissen Grad im Tumorgewebe an. Wird das Gewebe mit Licht geeigneter Wellenlänge bestrahlt, entstehen hochreaktive, aber kurzlebige chemische Substanzen, die schließlich den Zelttod herbeiführen. Die kurze Lebensdauer dieser toxischen Substanzen stellt sicher, daß der zytotoxische Effekt nur auf das Gewebe beschränkt ist, das dem Licht ausgesetzt ist. Auf diese Weise wird eine systemische Toxizität vermieden.
Photodynamic therapy (PDT) is a new approach to the local treatment of cancers. A photosensitizer, non-toxic in the dark, is administered to a patient. The photosensitizer is retained with some degree of selectivity by tumor tissue. On exposure to light of the appropriate wavelength, highly reactive but very short lived chemical species are produced which cause cell death. The short half life of these toxic species ensures that the cytotoxic effect is confined to the tissue exposed to the therapeutic light, thus avoiding systemic toxicity.
Background: Photodynamic therapy (PDT) is an effective laser treatment for locally advanced carcinoma and is promising as neoadjuvant chemotherapy before surgery. The aim of this study was to clarify the adverse effects of PDT using a photosensitizer, talaporfin sodium (Laserphyrin®), for wound healing. Methodology: For PDT, a laser light with a wavelength of 660 nm and a frequency of 10 Hz with a total energy fluency of 60 J/cm2 was used. Macroscopic and histological findings of wound healing after PDT were examined in vivo (4-week-old male BALB/c mice). Results: In Model 1, in which skin was cut at 0, 3, 7 days after PDT (n=3, each), wounds were similarly healed 7 days after cutting in all groups, and regenerating epithelium and the number of fibroblasts on histological findings were not different. In Model 2, in which skin defects were created before or after PDT, the size of the defects was larger at day 7 in the groups with skin defects before or after PDT in comparison with groups with no PDT. However, macroscopic wound healing at day 14 was complete in all groups and there were no significant differences among the groups by this point. Histological findings of skin defects at day 14 showed no significant difference in terms of regenerating epithelium and number of fibroblasts in each group with or without PDT. Conclusions: PDT did not influence wound healing and can be safely applied before surgical therapy.
Background and Objective
In an attempt to develop a new therapeutic approach for highly localized thermal destruction of tissue targets that lack natural pigmentation, the potential of in-vivo dye-enhanced photothermal therapy (PTT) was investigated. PTT involves the application of an exogenous absorber, which accumulates in metabolically active tissues, followed by non-invasive light irradiation, using appropriate wavelengths, exposure durations, and irradiances. The chromophore used, palladium(II) octabutoxynaphthalocyanine (PdNc(OBu)8), strongly absorbs in the near infrared wavelength range which thus permits good penetration depth of the exciting light. The predominant de-excitation routes of the chromophore are radiationless thermal processes.Materials and Methods
Using a BALB/c mouse model with a subcutaneously implanted syngeneic EMT6 adenocarcinoma, 96–100 hours after intraperitoneal application of PdNc(OBu)8, tumor, and surrounding tissue were irradiated with a 830 nm continuous wave diode laser applying 30 Wcm−2 for 10–20 seconds. Treatment parameters were based on theoretical calculations.ResultsHistological evaluation of thermal effects on tumor and normal tissue showed that after PdNc(OBu)8-enhanced photothermal treatment, highly localized and selective thermal damage of the tumors was achieved. The necrotic tumor area was invaded by inflammatory cells, including neutrophils, macrophages, mast cells, and lymphocytes, thus reflecting a prominent host immune response. In tumors treated with PTT for 15 or 20 seconds, respectively, only few surviving tumor cells were detected underneath the epidermis. Adjacent peripheral normal tissue including skin and muscle remained completely unaffected.Conclusion
This study highlights the potential of achieving irreversible thermal tissue damage closely localized to the target tissue when PdNc(OBu)8 is used in combination with continuous-wave light. Lasers Surg. Med. © 2015 Wiley Periodicals, Inc.
The photosensitizing effect of haematoporphyrin (HP) on human cells of the established line NHIK 3025 has been studied. Fluorescence measurements show that HP is bound to these cells. Serum proteins also bind HP, and the presence of 10% human serum during incubation with HP (3 X 10(-4)M) reduces the cellular uptake of HP by 75% or more. The photosensitized inactivation is enhanced when the cells are suspended in D2O-buffer during irradiation. This indicates that singlet oxygen is involved in the inactivation. Two findings indicate that the photoinduced damage is repairable: firstly, the fraction of cells surviving a given light dose decreases with decreasing irradiation temperature, and secondly, the survival curves have a shoulder at low exposures of light.
Images
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Fig. 5
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 solubilities of He, Ne, Ar, N2, O2, CO and CO2 in olive oil have been determined in the temperature range 24–56 C. The gas solubility apparatus was a considerably improved
version of the one reported by Morrison and Billett and gave a precision, depending on the gas solvent system of ±0.2% to
±1.0%. Plots of log L, the Ostwald coefficient, and log α, the Bunsen coefficient, against 1/TK were linear and showed a small
temperature dependence for CO2. The enthalpy and entropy changes corresponding to the solution process were calculated. The partition coefficients of the
gases between olive oil and water were calculated using reported values for the solubility of the gases in water. These results
have been used to test and extend the Meyer-Overton theory of transport through the cell membrane.
Hematoporphyrin derivative (HpD) photoradiation therapy (PRT) has been reported as an effective treatment for a variety of tumors (1,2). This technique relys on the tumor localizing and photosensitization potential of HpD to selectively destroy tumors.
Nanosecond laser flash photolysis has been used to generate and characterise the triplet state of haematoporphyrin in a number of homogeneous and microheterogeneous environments. First-order triplet decay rate constants lie in the range (1–3)× 104 s–1 in detergents and homogeneous environments but are higher [(4–6)× 104 s–1] in liposomal and cellular environments. Values of the singlet–triplet extinction coefficients reflect the degree of aggregation of the haematoporphyrin in the various environments and imply that aggregation is extensive in phosphate buffers, liposomal and cellular environments but is small in detergents and homogeneous solution. Quantum yields for triplet formation are near unity for all the systems studied.
Abstract— Aqueous solutions of hematoporphyrin and hematoporphyrin derivatives were exposed to light. When present in such solutions tryptophan is degraded by a singlet oxygen mechanism. This is true for excitation at 396 nm, where porphyrin monomers have their absorption maximum, as well as for excitation at 360 nm, where porphyrin aggregates seem to absorb strongly. The quantum yield of singlet oxygen production is similar within 25% for excitation at 396 and 360 nm while the fluorescence quantum yield is more than a factor 2 lower for excitation at 360 nm than for excitation at 396 nm. Photoexcitation of the clinically used hematopotophyrin derivatives photofrin I and photofrin II produces singlet oxygen with significantly smaller yields than photoexcitation of hematoporphyrin. Thus, the aggregates present in solutions of photofrin I and photofrin II are of a different nature than those present in aqueous solutions of hematoporphyrin.
Administration of hematoporphyrin derivative i.v. followed by local exposure to red light has resulted in complete or partial response in 111 of 113 cutaneous or s.c. malignant lesions. Tumors treated have included carcinomas of the breast, colon, prostate, squamous cell, basal cell, and endometrium; malignant melanoma; mycosis fungoides; chondrosarcoma; and angiosarcoma. No type has been found to be unresponsive. In several cases complete clearing of chest wall metastatis has been achieved in treated areas. Deep-seated and pigmented tumors required a higher dose of drug for effective treatment than did the more superficial and nonpigmented lesions. A high therapeutic ratio between tumor and skin response has been obtained by allowing at least 3 days between drug injection and exposure to the therapeutic light for 2,5-mg/kg doses and at least a 4-day interval for 5.0-mg/kg doses.
— Exposure of Raji cells to haematoporphyrin derivative (HPD) and red light caused marked cytotoxicity. This was completely inhibited under anaerobic conditions. By using sodium dithionite in aqueous solutions, precise and graded oxygen concentrations could be achieved. Cytotoxicity was directly proportional to the oxygen concentration of the medium until a maximum was reached at a pO2 of 90 mm Hg. Sodium dithionite did not affect the viability of test cells and did not alter the chromatographic profile of HPD. Dithionite did not interfere with the uptake of HPD by cells. Dependency of phototoxicity upon aerobic conditions suggests that the cytotoxic agent is derived from oxygen and is consistent with the hypothesis that singlet oxygen and/or oxygen-derived free radicals play an important role in photochemotherapy with HPD.
Acute normal skin toxicity induced by porphyrin photosensitization has been examined using albino mice. Oxic and anoxic (clamped) skin was exposed to red light (630 nm) 24 h following administration of hematoporphyrin derivative (HpD) or Photofrin II (the active component of HpD). Experiments were also performed to determine the effect of sodium pentobarbital anesthesia on HpD and Photofrin II photosensitization of normal skin. Results from this study demonstrated that comparable levels of acute skin damage were induced by HpD and Photofrin II under oxic conditions but neither porphyrin produced any apparent phototoxicity under anoxic conditions. In addition, the level of skin damage induced by porphyrin photosensitization was not affected by sodium pentobarbital anesthesia.
We conducted a trial of photoradiation therapy of cancer at the University of California at Irvine. The basis of this technique is a photochemical reaction between an i.v.-injected material, hematoporphyrin derivative, and red light (wavelength, 630 nm). Hematoporphyrin derivative localized in malignant tissue, resulting in selective destruction of cancer cells upon illumination with red light. One hundred twenty-eight sites of recurrent cancer or premalignant lesions were treated in 37 patients. Of this group, 35 patients had recurrent cancer refractory to conventional therapy, and two had premalignant lesions. Favorable responses were achieved in 67% of the sites treated. The dose of hematoporphyrin derivative used in this study ranged from 2 to 5 mg/kg with the majority of patients receiving 3 mg/kg. Total light dose administered appeared to be the most critical parameter evaluated. Light doses in excess of 20 J/sq cm generally resulted in blistering and necrosis of intact skin, while no appreciable increase in response was observed. Photoradiation therapy has demonstrable efficacy in cancer therapy and avoids much of the morbidity of current conventional techniques.
The lysis of phosphatidylcholine (PC) liposomes was sensitized to visible light (>500nm) by hematoporphyrin (HP) incorporated in the liposomes (0.09-1.5%, wt/wt) or in the external buffer (1-15 μM). The lytic mechanism changed from the Type II pathway mediated by singlet oxygen (1O2) at low HP concentrations to the anoxic, Type I pathway at high HP concentrations. Spectral measurements of HP in aqueous and organic solvents indicate that the HP was not aggregated (monomers and/or dimers) for Type II sensitization and aggregated for Type I conditions. High concentrations of azide (>0.1 M) or DABCO (>0.5 M) were protective with high HP concentration under oxic and anoxic conditions, which cannot involve the scavenging of 1O2. Feasible protective mechanisms are quenching of the HP triplet state by high azide and repair of the damaged membrane by DABCO via an electron transfer process. There was significant protection against lysis under Type I conditions by low concentrations of ferricyanide (>1 mM), indicative of an electron transfer mechanism. The incorporation of 22 mol % cholesterol in PC liposomes with 1% HP had no effect on the lytic efficiency for oxic and anoxic conditions. Dipalmitoylphosphatidylcholine liposomes incorporating 1% HP showed negligible photosensitized lysis at 50°C compared with PC liposomes with 1% HP at 25°C. The promotion of photosensitized lysis by hydrodynamic agitation observed in prior work with methylene blue (Grossweiner and Grossweiner, 1982) was significant with HP sensitization for both Type I and Type II conditions. Actinometry with PC liposomes incorporating 1% HP indicated that photosensitized lysis was very inefficient, requiring many absorbed quanta per lysed liposome. Preliminary experiments with crude hematoporphyrin derivative (Hpd) showed similar concentration effects on lytic efficiency, where PC liposomes incorporating 0.1% (wt/wt) Hpd were strongly sensitized by oxygen, whereas sensitization by oxygen was insignificant with 3.1% Hpd. The results with HP and crude Hpd indicate that lytic damage in a biomembrane does not necessarily require oxygenation.
Photoradiation therapy (phototherapy) is a recently introduced treatment for malignant tumours, which depends on the activation of a photoreactive drug selectively localized to tumours. An experience in 27 patients with haematoporphyrin derivative is described. The haematoporphyrin derivative was activated by light of 630-nm wavelength, which was delivered to cutaneous tumours from a specially designed incandescent lamp and to deep tumours through a quartz fibre from a laser system. Tumours were eradicated in five patients and incomplete tumour destruction was observed in 14 others. The only significant side effect was temporary cutaneous photosensitivity. This form of treatment has considerable potential, particularly when other treatments have either failed or cannot be applied. However, it is premature to formulate indications for its use. Rapid technological developments can be anticipated which will greatly enhance the efficacy of photodynamic destruction of tumours.
The use of hematoporphyrin derivative to detect and delineate extent of malignant lesions is based upon its tendency to accumulate and be retained in malignant tissue to a greater degree than in many normal tissues. Its presence can be readily observed by its characteristic red fluorescence.
Hematoporphyrin therapy of endobronchial lung cancer
- D R Doiron
- O Bafchum
Doiron. D. R., and Bafchum, O. Hematoporphyrin therapy of endobronchial lung cancer. In: A. Andreoni and R. Cubeddu (eds.), Porphyrins in Tumor Phototherapy,pp. 395-403. Corp., 1984
Studies on mechanism of tumor destruction by photoradiation therapy In: Clayton Symposium on Porphyrin Localization and Treatment of Tumors
- B W Henderson
- T J Dougherty
Henderson, B. W., and Dougherty, T. J. Studies on mechanism of tumor
destruction by photoradiation therapy. In: Clayton Symposium on Porphyrin
Localization and Treatment of Tumors. New York: Alan R. Liss. Inc., in press,
1985.