Photodynamic therapy in head and neck cancer

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

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

Progress and trends in photodynamic therapy research in oral science: A bibliometric analysis

BACKGROUND

Photodynamic therapy is garnering increasing attention in oral science. Despite its promising potential, further exploration is warranted to delve into the research paradigms and evolving trends within oral science. Therefore, this study aimed to conduct a comprehensive bibliometric analysis of photodynamic therapy in oral science (PDTOS), investigating research landscapes, identifying key contributors, analyzing collaborative networks, pinpointing emerging research directions, and exploring factors influencing high citations.

METHODS

Research and review articles in PDTOS were retrieved from the Web of Science Core Collection database up to December 31, 2023. The R package "bibliometrix" and VOSviewer were utilized for visualizing collaboration networks and keyword co-occurrence, alongside trend analysis. Negative binomial regression was used to model factors affecting citation counts.

RESULTS

A total of 2784 articles with significant international collaboration (23.14 %) were analyzed. Brazil, China, the USA, Iran, and Italy led in publications, with predominant USA-European collaborations. The University of Sao Paulo in Brazil was the most published institution in the field. Photodiagnosis and Photodynamic Therapy was the core journal in the field and has the highest number of publications. The main research fields included photodynamic therapy, antibacterial and anticancer treatment, management, and peri‑implant periodontitis, with a recent focus on peri‑implantitis. Factors such as international cooperation, funding, article age, type, author count, and references significantly influenced citations.

CONCLUSIONS

This research provided valuable insights into PDTOS trends and knowledge structures. These findings underscored a significant increase in the number of PDTOS publications, urging strengthened international cooperation. Emerging research has focused on peri‑implantitis and nano-photosensitizer materials. Authors should consider various citation-related factors in their research endeavors.

Photodynamic Therapy for Eye, Ear, Laryngeal Area, and Nasal and Oral Cavity Diseases: A Review

Photodynamic therapy (PDT) has emerged as a promising modality for the treatment of various diseases. This non-invasive approach utilizes photosensitizing agents and light to selectively target and destroy abnormal cells, providing a valuable alternative to traditional treatments. Research studies have explored the application of PDT in different areas of the head. Research is focusing on a growing number of new developments and treatments for cancer. One of these methods is PDT. Photodynamic therapy is now a revolutionary, progressive method of cancer therapy. A very important feature of PDT is that cells cannot become immune to singlet oxygen. With this therapy, patients can avoid lengthy and costly surgeries. PDT therapy is referred to as a safe and highly selective therapy. These studies collectively highlight the potential of PDT as a valuable therapeutic option in treating the head area. As research in this field progresses, PDT may become increasingly integrated into the clinical management of these conditions, offering a balance between effectiveness and minimal invasiveness.

Emerging potential of phototherapy in management of symptomatic oral lichen planus: A systematic review of randomised controlled clinical trials

Phototherapy incorporating photobiomodulation therapy and antimicrobial photodynamic therapy has been utilised as antioxidants in symptomatic oral lichen planus (OLP) management; however, its role of intervention remains controversial. The aim of this systematic review of CRD42021227788 PROSPERO (an international prospective register of systematic reviews in health and social care) registration number was to oversee and determine phototherapy efficacy in patients with symptomatic OLP, identifying and bridging the literature gaps by proposing recommendations for future studies. A search strategy was developed in consistent with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Various electronic databases were exercised to search for randomised controlled clinical trials (RCTs). Several search engines were employed to analyse a total of 177 studies of which nine included. A wide range of utilised laser and light-emitted diode wavelengths between 630 and 808 nm and irradiance ranged between 10 and 13 mW/cm² were noted. 67% of studies reported a high risk of bias and a high heterogeneity obtained from numerical data for quantitative analysis, therefore meta-analysis was impossible to conduct. Despite inconsistency and diversity in phototherapy parameters, treatment protocols, photosensitiser (type, concentration and method of application) and outcome assessment tools, the majority of the studies showed positive results compared with standard care treatments. Hence, a necessity to perform well-designed RCTs with robust methodology is warranted, after acknowledging the current drawbacks and addressing the suggested recommendations highlighted in our review. Moreover, advanced knowledge in understanding further phototherapy-antioxidants molecular mechanistic in symptomatic OLP is required.

Biodistribution of the photosensitizer temoporfin after in vivo topical application of temoporfin-loaded invasomes in mice bearing subcutaneously implanted HT29 tumor

Temoporfin (mTHPC) has a great potential for the topical photodynamic therapy. However, it presents a highly hydrophobic second generation photosensitizer with low percutaneous penetration. In order to use mTHPC for dermal/transdermal delivery it is necessary to employ some of the penetration enhancement methods. In this study invasomes were used as a highly effective drug nanocarrier system to enhance its skin penetration, being composed of non-hydrogenated soybean lecithin (10% w/v), ethanol (3.3%w/v), a mixture of terpenes (1% w/v of the mixture cineole:citral:d-limonene = 45:45:10 v/v) and phosphate buffer saline up to 100% w/v. A pharmacokinetic/biodistribution study was performed in mice bearing s.c. implanted human colorectal tumor HT29 upon the application of mTHPC-loaded invasomes onto the skin above the underlying tumor. The aim was to obtain the biodistribution profile of mTHPC i.e. to gain data on mTHPC-distribution in the body (tumor, treated skin, muscle, blood, liver and untreated skin) of mice after the topical application of mTHPC-loaded invasomes. The results revealed that a significant mTHPC-amount was found in treated skin already after 2 h of incubation time. As to the tumor, significant amounts were found after 12 h, while the highest mTHPC-amount was found after 24 h. This study showed that invasomes applied onto the skin may deliver mTHPC to the tumor being necessary for PDT. Since mTHPC was also found in blood and liver, transdermal mTHPC delivery was confirmed. In conclusion, mTHPC-invasomes could be used for topical PDT of cutaneous and subcutaneous lesions, however with general photoxicity induced by systemic apsorption of mTHPC lasting only for 2 weeks. Additionally, due to systemic absorption of mTHPC after invasomes application onto the skin, they could be used transdermally for the PDT treatment of diseases, which need systemic drug absorption. However, it should be emphasized that mice were used in the study, differing in the skin properties compared to human skin. Thus, additional studies should be conducted.

Critical PDT Theory III: Events at the Molecular and Cellular Level

Photodynamic therapy (PDT) is capable of eradicating neoplastic cells that are accessible to sufficient light and oxygen. There is adequate information now available for assessing conditions where PDT might be the therapy of choice, but limited access to clinical facilities and impediments to regulatory approval of new agents have limited clinical usage. Early reports mainly involved clinical data with few thoughts towards finding death pathways. In 2022, there is a clear understanding of the determinants of successful tumor eradication. While PDT may be the optimal method for many clinical indications, support for this approach has lagged. This report provides a commentary on some elements of recent progress in PDT at the molecular and cellular levels, along with a discussion of some of the limitations in current research efforts.

The Role of Photodynamic Therapy in Triggering Cell Death and Facilitating Antitumor Immunology

Cancer is a major threat to human health because of its high mortality, easy recurrence, strong invasion, and metastasis. Photodynamic therapy (PDT) is a promising minimally invasive treatment for tumor. Compared with traditional treatment methods, PDT is less invasive and does not easily damage normal tissues. Most of the effects of this treatment are due to the direct effects of singlet oxygen together with reactive oxygen species. PDT can provide the source of active oxygen for the Fenton reaction, which enhances ferroptosis and also improves the efficacy of PDT in antitumor therapy. Additionally, in contrast to chemotherapy and radiotherapy, PDT has the effect of stimulating the immune response, which can effectively induce immunogenic cell death (ICD) and stimulate immunity. PDT is an ideal minimally invasive treatment method for tumors. In this paper, according to the characteristics of anti-tumor immunity of PDT, some tumor treatment strategies of PDT combined with anti-tumor immunotherapy are reviewed.

Biophotonics in Dentistry

The aim of this review paper is to concentrate on the use and application of photonics in dentistry. More than one hundred review and research articles were comprehensively analysed in terms of applications of photonics in dentistry, including surgical applications, as well as dental biomaterials, diagnosis and treatments. In biomedical engineering, various fields, such as biology, chemistry, material and physics, come together in to tackle a disease/disorder either as a diagnostic tool or an option for treatment. Engineers believe that biophotonics is the application of photonics in medicine, whereas photonics is simply a technology for creating and connecting packets of light energy, known as photons. This review paper provides a comprehensive discussion of its main elements, such as photoelasticity, interferometry techniques, optical coherence tomography, different types of lasers, carbon nanotubes, graphene and quantum dots.

Utility of Photodynamic Therapy in Dentistry: Current Concepts

The significant growth in scientific and technological advancements within the field of dentistry has resulted in a wide range of novel treatment modalities for dentists to use. Photodynamic therapy (PDT) is an emerging, non-invasive treatment method, involving photosensitizers, light of a specific wavelength and the generation of singlet oxygen and reactive oxygen species (ROS) to eliminate unwanted eukaryotic cells (e.g., malignancies in the oral cavity) or pathogenic microorganisms. The aim of this review article is to summarize the history, general concepts, advantages and disadvantages of PDT and to provide examples for current indications of PDT in various subspecialties of dentistry (oral and maxillofacial surgery, oral medicine, endodontics, preventive dentistry, periodontology and implantology), in addition to presenting some images from our own experiences about the clinical success with PDT.

Photodynamic therapy in oral lichen planus: A prospective case-controlled pilot study

Oral lichen planus (OLP) is a common, chronic relapsing inflammatory disorder of the mucous membranes, which causes major discomfort. Current treatment includes topical/systemic glucocorticoids, immune modulators and systemic immunosuppressants, which may lead to considerable side-effects. The aim of this study was to determine the clinical and immunological efficacy of photodynamic therapy (PDT) in OLP as an alternative, easy-to-use, safe and non-invasive treatment. Twenty patients with OLP were treated with PDT in a prospective case-controlled pilot-study. PDT was performed on the most extensive oral lesion in 4 sessions (day 1, 3, 7, 14). Peripheral blood and lesional T cells were analysed before (day 1) and after PDT treatment (day 28). PDT led to a statistically significant reduction of clinical parameters (lesion size, ABSIS, Thongprasom-score) and improvement of all evaluated quality-of-life (QOL) items. The clinical improvement was accompanied by a significant decrease of the relative number of CD4+ and CD8+ T cells in mucosal OLP-lesions. Furthermore, CXCL10 plasma levels were decreased and the number of activated peripheral CD4 + CD137+ and CD8 + CD137+ T cells and IL-17-secreting T cells was diminished. PDT treatment in OLP leads to lesion reduction and improvement of QOL, and induces local and systemic anti-inflammatory effects. The study identifies PDT as a novel therapeutic option in OLP.

Comparison of the effect of photodynamic therapy and topical corticosteroid on oral lichen planus lesions

OBJECTIVE

In this study, the effect of photodynamic therapy with topical corticosteroid in oral lichen planus patients was compared.

MATERIAL AND METHODS

In this randomized, double-blind clinical trial, eight patients with bilateral oral OLP lesions were recruited. Toluidine blue was applied on the lesions of both sides; a 660-nm diode laser InGaAlP was irradiated for 10 min (power: 25 mW, fluence: 19.23 J/cm² , probe cross section: 0.78 cm² ) for three sessions. In the control side of the oral mucosa, only sham laser was used. Follow-up sessions were held on weeks 3 and 7. In week 3, oral paste triamcinolone acetonide 0.1% was prescribed. Response rates were assessed clinically by VAS, Thongprasom sign scoring, clinical severity index, efficacy indices, and the amount of reduction in the size of the lesions. The Mann-Whitney test was used to evaluate the treatment outcomes.

RESULTS

In spite of the control side, all scores improved significantly between sessions 0 and 4 for the intervention side. The differences between the changes in almost all scores between sessions 0 and 4 in both the intervention and control sides were significantly considerable (p value < .05).

CONCLUSION

Photodynamic therapy can be used as an alternative therapy alongside standard methods or as a new modality for refractory OLP.

A clinical evaluation of efficacy of photodynamic therapy in treatment of reticular oral lichen planus: A case series

Background The aim of the study was to clinically evaluate the efficacy of photodynamic therapy in treatment of reticular oral lichen planus (OLP). Methods Fifty patients aged 26-84, with 124 OLP lesions in total, underwent photodynamic therapy (PDT) mediated with topically applied 5% 5-aminolevulinic acid. ALA was activated by a custom-made diode lamp with a high-power LED emitting light at 630 nm and 300 mW delivered through an optical fiber probe. A light exposure dose was 150 J/cm2. The therapy comprised of 10 weekly illumination sessions. The lesions' response was macroscopically measured in millimeters with a periodontal probe and clinically evaluated at each session, then on completion of the series and throughout the 12-month follow-up. Results The baseline mean size of lesions was 3.99 cm2±3.73. The lesions on the buccal mucosa and lips (lining mucosa) were larger than those on the gingiva and tongue (masticatory mucosa) - 4.58 cm2±4.01 and 2.93 cm2±2.91 respectively. On completion of the therapy 109 sites improved, including 46 in complete remission. The mean reduction in size was 62.91% (p = 0.000000). 12-month after therapy mean reduction of the lesions was 78.7% (p = 0.000000), specifically 79.48% (p = 0.000000) within the lining mucosa and 76.11% on the masticatory mucosa. Conclusions The results proved that ALA-mediated photodynamic therapy with a 630 nm light was effective and as such it can be used as an optional treatment for symptomatic OLP.

Study on Liposomal Encapsulation of New Bodipy Sensitizers for Photodynamic Therapy

We report a series of four efficient photosensitizers (PSs) based on a Bodipy core for photodynamic therapy (PDT). In the absence of hydrophilic functional groups, these PSs have been encapsulated in liposomes and examined for photocytotoxicity against human ovarian carcinoma cell line (SK-OV-3). The IC₅₀ values obtained are as low as 0.350 μM, which compete with the classical photosensitizer chlorine E6 (IC₅₀ = 0.39 μM) under similar experimental conditions.

Photodynamic treatment outcomes of potentially-malignant lesions and malignancies of the head and neck region: A systematic review

AIM

The aim of the present study was to systematically review the efficacy of photodynamic therapy (PDT) in the management of oral potentially-malignant disorders (PMDS) and head and neck squamous cell carcinoma (HNSCC).

METHODS

From 1985 to 2015, PubMed/Medline, Google Scholar, EMBASE, and ISI Web of Knowledge were searched using different combinations of the following key words: PDT, oral precancer, leukoplakia, erythroplakia, erythroleukoplakia, verrucous hyperplasia, oral submucous fibrosis, and HNSCC. Review articles, experimental studies, case reports, commentaries, letters to the editor, unpublished articles, and articles published in languages other than English were excluded.

RESULTS

Twenty-six studies were included in the present study. The number of patients ranged from 2 to 147, with a mean age of 50-67 years. The reported numbers of PMDS and HNSCC ranged between 5 and 225. Photosensitizers used were aminolevulinic acid, meta-tetrahydroxyphenylchlorin, Foscan, hematoporphyrin derivatives, Photofrin, Photosan, and chlorine-e6. Laser wavelength, power density, irradiation duration were 585-652 nm, 50-500 mW/cm² , and 1-143 minutes, respectively. Complete, partial, and no response to PDT was found in 22.58%-100%, 4%-66%, and 0%-38.70% of PMDS, respectively, and 16%-100% of complete response in HNSCC patients.

CONCLUSION

PDT is effective in the management of PMDS and HNSCC.

Photodynamic Therapy in Dentistry

Photodynamic therapy (PDT), also known as photoradiation therapy, phototherapy, or photochemo-therapy, involves the use of a photoactive dye (photosensitizer) that is activated by exposure to light of a specific wavelength in the presence of oxygen. The transfer of energy from the activated photosensitizer to available oxygen results in the formation of toxic oxygen species, such as singlet oxygen and free radicals. These very reactive chemical species can damage proteins, lipids, nucleic acids, and other cellular components. Applications of PDT in dentistry are growing rapidly: the treatment of oral cancer, bacterial and fungal infection therapies, and the photodynamic diagnosis (PDD) of the malignant transformation of oral lesions. PDT has shown potential in the treatment of oral leukoplakia, oral lichen planus, and head and neck cancer. Photodynamic antimicrobial chemotherapy (PACT) has been efficacious in the treatment of bacterial, fungal, parasitic, and viral infections. The absence of genotoxic and mutagenic effects of PDT is an important factor for long-term safety during treatment. PDT also represents a novel therapeutic approach in the management of oral biofilms. Disruption of plaque structure has important consequences for homeostasis within the biofilm. Studies are now leading toward selective photosensitizers, since killing the entire flora leaves patients open to opportunistic infections. Dentists deal with oral infections on a regular basis. The oral cavity is especially suitable for PACT, because it is relatively accessible to illumination.

Prospects in the Application of Photodynamic Therapy in Oral Cancer and Premalignant Lesions

Oral cancer is a global health burden with significantly poor survival, especially when the diagnosis is at its late stage. Despite advances in current treatment modalities, there has been minimal improvement in survival rates over the last five decades. The development of local recurrence, regional failure, and the formation of second primary tumors accounts for this poor outcome. For survivors, cosmetic and functional compromises resulting from treatment are often devastating. These statistics underscore the need for novel approaches in the management of this deadly disease. Photodynamic therapy (PDT) is a treatment modality that involves administration of a light-sensitive drug, known as a photosensitizer, followed by light irradiation of an appropriate wavelength that corresponds to an absorbance band of the sensitizer. In the presence of tissue oxygen, cytotoxic free radicals that are produced cause direct tumor cell death, damage to the microvasculature, and induction of inflammatory reactions at the target sites. PDT offers a prospective new approach in controlling this disease at its various stages either as a stand-alone therapy for early lesions or as an adjuvant therapy for advanced cases. In this review, we aim to explore the applications of PDT in oral cancer therapy and to present an overview of the recent advances in PDT that can potentially reposition its utility for oral cancer treatment.

The PARP inhibitor PJ-34 sensitizes cells to UVA-induced phototoxicity by a PARP independent mechanism

A combination of a photosensitizer with light of matching wavelength is a common treatment modality in various diseases including psoriasis, atopic dermatitis and tumors. DNA damage and production of reactive oxygen intermediates may impact pathological cellular functions and viability. Here we set out to investigate the role of the nuclear DNA nick sensor enzyme poly(ADP-ribose) polymerase 1 in photochemical treatment (PCT)-induced tumor cell killing. We found that silencing PARP-1 or inhibition of its enzymatic activity with Veliparib had no significant effect on the viability of A431 cells exposed to 8-methoxypsoralen (8-MOP) and UVA (2.5J/cm(2)) indicating that PARP-1 is not likely to be a key player in either cell survival or cell death of PCT-exposed cells. Interestingly, however, another commonly used PARP inhibitor PJ-34 proved to be a photosensitizer with potency equal to 8-MOP. Irradiation of PJ-34 with UVA caused changes both in the UV absorption and in the 1H NMR spectra of the compound with the latter suggesting UVA-induced formation of tautomeric forms of the compound. Characterization of the photosensitizing effect revealed that PJ-34+UVA triggers overproduction of reactive oxygen species, induces DNA damage, activation of caspase 3 and caspase 8 and internucleosomal DNA fragmentation. Cell death in this model could not be prevented by antioxidants (ascorbic acid, trolox, glutathione, gallotannin or cell permeable superoxide dismutase or catalase) but could be suppressed by inhibitors of caspase-3 and -8. In conclusion, PJ-34 is a photosensitizer and PJ-34+UVA causes DNA damage and caspase-mediated cell death independently of PARP-1 inhibition.

Nanostructured lipid carrier in photodynamic therapy for the treatment of basal-cell carcinoma

Topical photodynamic therapy (PDT) is a promising alternative for malignant skin diseases such as basal-cell carcinoma (BCC), due to its simplicity, enhanced patient compliance, and localization of the residual photosensitivity to the site of application. However, insufficient photosensitizer penetration into the skin is the major issue of concern with topical PDT. Therefore, the aim of the present study was to enable penetration of photosensitizer to the different strata of the skin using a lipid nanocarrier system. We have attempted to develop a nanostructured lipid carrier (NLC) for the topical delivery of second-generation photosensitizer, 5-amino levulinic acid (5-ALA), whose hydrophilicity and charge characteristic limit its percutaneous absorption. The microemulsion technique was used for preparing 5-ALA-loaded NLC. The mean particle size, polydispersity index, and entrapment efficiency of the optimized NLC of 5-ALA were found to be 185.2 ± 1.20, 0.156 ± 0.02, and 76.8 ± 2.58%, respectively. The results of in vitro release and in vitro skin permeation studies showed controlled drug release and enhanced penetration into the skin, respectively. Confocal laser scanning microscopy and cell line studies respectively demonstrated that encapsulation of 5-ALA in NLC enhanced its ability to reach deeper skin layers and consequently, increased cytotoxicity.

Ruthenium porphyrin-induced photodamage in bladder cancer cells

Photodynamic therapy (PDT) is a noninvasive treatment for solid malignant and flat tumors. Light activated sensitizers catalyze photochemical reactions that produce reactive oxygen species which can cause cancer cell death. In this work we investigated the photophysical properties of the photosensitizer ruthenium(II) porphyrin (RuP), along with its PDT efficiency onto rat bladder cancer cells (AY27). Optical spectroscopy verified that RuP is capable to activate singlet oxygen via blue and red absorption bands and inter system crossing (ISC) to the triplet state. In vitro experiments on AY27 indicated increased photo-toxicity of RuP (20μM, 18h incubation) after cell illumination (at 435nm), as a function of blue light exposure. Cell survival fraction was significantly reduced to 14% after illumination of 20μM RuP with 15.6J/cm(2), whereas the "dark toxicity" of 20μM RuP was 17%. Structural and morphological changes of cells were observed, due to RuP accumulation, as well as light-dependent cell death was recorded by confocal microscopy. Flow cytometry verified that PDT-RuP (50μM) triggered significant photo-induced cellular destruction with a photoxicity of (93%±0.9%). Interestingly, the present investigation of RuP-PDT showed that the dominating mode of cell death is necrosis. RuP "dark toxicity" compared to the conventional chemotherapeutic drug cisplatin was higher, both evaluated by the MTT assay (24h). In conclusion, the present investigation shows that RuP with or without photoactivation induces cell death of bladder cancer cells.

[The use of the method of photodynamic therapy for the treatment of the patients presenting with primary and recurrent laryngeal cancer]

The objective of the present study was to evaluate the effectiveness of the method of photodynamic therapy (PDT) for the treatment of the patients presenting with primary and recurrent laryngeal cancer. A total of 20 patients at the age from 46 to 82 (mean 61.3±7.5) years suffering from laryngeal cancer (17 men and 3 women) were available for the observation. PDT was based on the use of «Atkus» lasers (Russia) operated at a wavelength of 662 nm and a power up to 3 W as well as «Lagus» lasers(wavelength: 662 nm, power: up to 3 W). It was shown that the effective treatment of laryngeal cancer by PDT is possible under condition of the thorough selection of the patients with a definite growth type and localization of the tumour. Complete resorption (CR) was achieved in 100% of the patients with the early (I-II) stages of laryngeal cancer and in 90% of those having exophyticneoplasms less than 1 cm in size. Moreover, the beneficial effect of PDT was documented in the treatment of limited relapses of laryngeal cancer in tracheostoma following combined therapy. It is concluded that the proposed method can be recommended for the palliative care in order to reach homeostasis in the patients with extended bleeding tumours and also for the reduction of their volume andrecanalization of the trachea to improve the patients' quality of life. The authors maintain that PDT can be in many cases performed under the outpatient conditions.

Clinical Approach of High Technology Techniques for Control and Elimination of Endodontic Microbiota

The main goal in endodontic treatment is to eradicate or at least reduce intraradicular microbial population to levels that are more compatible with periapical lesions healing process. Since endodontic infections are polymicrobial in nature, intraradicular survival of endodontic microbiota and their pathogenic properties are influenced by a combination of their virulence factors. The purpose of this article is to review the endodontic microbiota and their respective virulence attributes, as well as perform a literature review of the effects of disinfection procedures in the treatment of endodontic infections to gain best practices. Conventional technique for root canal preparation includes mechanical debridement and application of antimicrobial irrigants. Recently, laser irradiation has been used to enhance the results of root canal treatment through its thermal effect. To reduce thermal side effects, laser activated irrigation (LAI) and photon induced photoacoustic streaming (PIPS) were introduced. Antimicrobial photodynamic therapy (aPDT) by photochemical reaction uses light at a specific wavelength to activate a nontoxic photosensitizer (PS) in the presence of oxygen to produce cytotoxic products. Different PSs are used in dentistry including methylene blue (MB), toluidine blue O (TBO), indocyanine green (ICG) and curcumin. Among different options, ICG could be the best choice due to its peak absorption at wavelength of 808 nm, which coincides with the commercial diode laser devices. Also, this wavelength has more penetration depth compared to other wavelengths used in aPDT.

Comparative evaluation of photodynamic therapy using LASER or light emitting diode on cariogenic bacteria: An in vitro study

OBJECTIVE

The aim of this study was to evaluate in vitro the effect of photodynamic therapy (PDT) using LASER or light emitting diode (LED) on cariogenic bacteria (Streptococcus mutans [SM] and Lactobacillus casei [LC]) in bovine dentin.

MATERIALS AND METHODS

Twenty five fragments of dentin were contaminated with SM and LC strands and divided into five experimental groups according to the therapy they received (n = 5): C - control (no treatment), SCLED - no dye/LED application (94 J/cm(2)), SCLASER - no dye/LASER application (94 J/cm(2)), CCLED - dye/LED application (94 J/cm(2)) and CCLASER - dye/LASER application (94 J/cm(2)). The dye used was methylene blue at 10 mM. Dentin scrapes were harvested from each fragment and prepared for counts of colony forming units (CFU)/mL. The data were analyzed using Kruskal-Wallis, followed by Student-Newman-Keuls (α =0.05).

RESULTS

Regarding SM, groups CCLASER and CCLED showed a significant reduction in CFU/mL, which was statistically superior to the SCLASER, SCLED and C groups. Regarding LC, the groups CCLASER and CCLED caused a significant reduction in CFU/mL when compared with SCLASER, which showed intermediate values. SCLED and C had a lesser effect on reducing CFU/mL, where the former showed values similar to those of SCLASER.

CONCLUSIONS

In conclusion, PDT combined with LASER or LED and methylene blue had a significant antimicrobial effect on cariogenic bacteria in the dentin.

Clinical evaluation of photodynamic therapy efficacy in the treatment of oral leukoplakia

BACKGROUND

The aim of the study was clinical evaluation of photodynamic therapy efficacy in the treatment of oral leukoplakia lesions.

METHODS

Twenty-three consecutive patients aged 21-79 were included to the study. In all patients 44 homogeneous, flat leukoplakia lesions were clinically diagnosed and confirmed histopathologically. Photodynamic therapy was performed with the use of Photolon(®) photosensitizer, containing 20% Chlorine-e6 and 10% dimethyl sulfoxide and a semiconductor laser, with power up to 300mW and a wavelength of 660nm. Ten illumination sessions were conducted with the use of superficial light energy density of 90J/cm(2).

RESULTS

At baseline the mean size of leukoplakia lesion was 6.5±5.10cm(2) while after photodynamic therapy 3±2.99cm(2). Significant reduction (on average by 53.8%) of leukoplakia lesions sizes was observed after therapy. Twelve (27.27%) lesions had been completely cured, 22 (50%) partially cured, although 10 (22.73%) lasted unchanged. The efficacy of PTD was comparable in women and men irrespective of age. There have been no adverse site effects during therapy noted.

CONCLUSIONS

Within the limits of the study it can be concluded that photodynamic therapy with the use of Chlorine-e6 can lead to considerable reduction of oral leukoplakia lesions size thus may be useful in clinical practice. However there is a need of further studies on larger number of cases and longer follow-up time.

Vocal fold vibration after photofrin-mediated photodynamic therapy for treatment of early-stage laryngeal malignancies

OBJECTIVE/HYPOTHESIS

To analyze vocal fold vibration after photofrin-mediated photodynamic therapy (PDT) for the treatment of Tis and T1N0M0 squamous cell carcinoma (SqCCa) tumors of the larynx. It was hypothesized that key attributes of vocal fold vibration would return to baseline within 1-6 months of treatment.

STUDY DESIGN

Retrospective.

METHODS

Laryngovideostroboscopic data were retrospectively analyzed for eight patients with Tis-T1N0M0 SqCCa tumors of the larynx treated with photofrin-mediated PDT. Baseline and posttreatment videostroboscopy images of select vibratory characteristics of the vocal folds were randomized and analyzed by a speech-language pathologist and fellowship-trained laryngologist specializing in voice disorders.

RESULTS

Significant improvement in mucosal wave (P=0.003) and amplitude of vibration (P=0.004) occurred at greater than or equal to 20 weeks post-PDT compared with baseline. Comparing results within 5 weeks postprocedure to 10-19-weeks postprocedure revealed significant improvement in amplitude of vibration (P=0.013) and nonvibrating portion of the vocal fold (P=0.020). Comparing results within 5-weeks postprocedure to 20 or more weeks postprocedure revealed significant improvement in amplitude of vibration (P=0.001), mucosal wave (P=0.001), and nonvibrating portion of the effected fold (P=0.001).

CONCLUSION

Photofrin-mediated PDT allows for preservation of function and structure of the larynx without systemic toxicity; however, it may take 4-5 months or more for key vibratory characteristics of the vocal folds to recover posttreatment.

The electromagnetic spectrum: current and future applications in oncology

The electromagnetic spectrum is composed of waves of various energies that interact with matter. When focused upon and directed at tumors, these energy sources can be employed as a means of lesion ablation. While the use of x-rays is widely known in this regard, a growing body of evidence shows that other members of this family can also achieve oncologic success. This article will review therapeutic application of the electromagnetic spectrum in current interventions and potential future applications.

Clinical assessment of the efficacy of photodynamic therapy in the treatment of oral lichen planus

The study objective was clinical assessment of the efficacy of photodynamic therapy (PDT) in the treatment of oral lichen planus (OLP). There were 23 patients aged 31–82 included in the study with oral lichen planus diagnosed clinically and histopathologically. In all patients photodynamic therapy was performed with the use of chlorin e6 (Photolon^®), containing 20 % chlorin e6 and 10 % dimethyl sulfoxide as a photosensitizer. PDT was performed using a semiconductor laser, with power up to 300 mW and a wavelength of 660 nm. A series of illumination sessions was conducted with the use of superficial light energy density of 90 J/cm². Changes of lesion size were monitored at one, two, five, and ten PDT appointments from the series of ten according to the authors' own method. The sizes of clinical OLP lesions exposed to PDT were reduced significantly (on average by 55 %). The best effects were observed for the lesions on the lining mucosa (57.6 %). The therapy was statistically significantly less effective when masticatory mucosa was affected (reduction, 30.0 %). Due to substantial efficacy and noninvasiveness, PDT can be useful in the treatment of OLP lesions.

Liposomes in topical photodynamic therapy

INTRODUCTION

Topical photodynamic therapy (PDT) refers to topical application of a photosensitizer onto the site of skin disease which is followed by illumination and results in death of selected cells. The main problem in topical PDT is insufficient penetration of the photosensitizer into the skin, which limits its use to superficial skin lesions. In order to overcome this problem, recent studies tested liposomes as delivery systems for photosensitizers.

AREAS COVERED

This paper reviews the use of different types of liposomes for encapsulating photosensitizers for topical PDT. Liposomes should enhance the photosensitizers' penetration into the skin, while decreasing its absorption into systemic circulation. Only few photosensitizers have currently been encapsulated in liposomes for topical PDT: 5-aminolevulinic acid (5-ALA), temoporfin (mTHPC) and methylene blue.

EXPERT OPINION

Investigated liposomes enhanced the skin penetration of 5-ALA and mTHPC, reduced their systemic absorption and reduced their cytotoxicity compared with free drugs. Their high tissue penetration should enable the treatment of deep and hyperkeratotic skin lesions, which is the main goal of using liposomes. However, liposomes still do not attract enough attention as drug carriers in topical PDT. In vivo studies of their therapeutic effectiveness are needed in order to obtain enough evidence for their potential clinical use as carriers for photosensitizers in topical PDT.

Antimicrobial photodynamic therapy: An overview

Inflammatory periodontal disease caused by dental plaque is characterized by the clinical signs of inflammation and loss of periodontal tissue support. The mechanical removal of this biofilm and adjunctive use of antibacterial disinfectants and antibiotics have been the conventional methods of periodontal therapy. But the removal of plaque and the reduction in the number of infectious organisms can be impaired in sites with difficult access. The possibility of development of resistance to antibiotics by the target organism has led to the development of a new antimicrobial concept with fewer complications. Photodynamic therapy (PDT) involves the use of low power lasers with appropriate wavelength to kill micro organisms treated with a photosensitizer drug. PDT could be a useful adjunct to mechanical as well as antibiotics in eliminating periopathogenic bacteria.

Characterization and optimization of mTHPP nanoparticles for photodynamic therapy of head and neck cancer

OBJECTIVES

To characterize the properties of polymeric micelles containing different loading percentages of mTHPP, a photosensitizer for photodynamic therapy (PDT), with respect to fluorescence, singlet oxygen ((1)O(2)) yield, and in vitro cytotoxicity in head and neck cancer cells.

STUDY DESIGN

Laboratory study.

SETTING

Polymer chemistry laboratory.

SUBJECTS AND METHODS

Absorption and emission spectroscopy was used to characterize the mTHPP-loaded micelles. The (1)O(2) yield was measured to determine the efficiency of reactive oxygen species (ROS) generation. In vitro studies were conducted using the HN5 cells and confirmed with H2009 cells to determine the photodynamic efficacy. DNA assay and confocal microscopy was used to measure intracellular fluorescence.

RESULTS

The mTHPP micelles demonstrated the highest fluorescence intensity at 0.5% loading. The (1)O(2) generation of the micelles in solution peaked at 2% loading. Phototoxicity and dark toxicity experiments in HN5 and H2009 cells demonstrated that the best therapeutic index was achieved with the 2% loaded micelles with 100% cell cytotoxicity at a micelle concentration of 10 µg/mL and less than 10% dark cytotoxicity. In comparison, 10% loaded micelles demonstrated 100% cell cytotoxicity at a concentration of 20 µg/mL under both light and dark conditions. Confocal microscopy demonstrated increasing intracellular fluorescence with higher loading.

CONCLUSIONS

The 2% mTHPP-loaded micelles generated greater (1)O(2), and 0.5% loading led to the most efficient generation of fluorescence in solution. Higher mTHPP loading density led to increased cellular fluorescence and dark cytotoxicity. Overall, 2% mTHPP-loaded micelles provided the optimal composition for photodynamic therapy with the largest therapeutic window.

Histopathological change of oral malignant tumour and epithelial dysplasia subjected to photodynamic therapy

Objectives

The purpose of this study is to analyze the morphological change of cell nuclei and the change of proliferating activity of oral malignancy and epithelial dysplasia between before and after photodynamic therapy in order to predict recurrence.

Material and methods

We experienced 14 cases of oral squamous cell carcinoma, one case of verrucous carcinoma and seven cases of epithelial dysplasia treated by photodynamic therapy (PDT). The mean nuclear area (NA) and coefficient of variation of the nuclear area (NACV) of 100 nuclei per slide were calculated using computer-assisted image analysis in hematoxylin and eosin stained biopsy specimens before and after PDT. Additionally, proliferating cell nuclear antigen (PCNA) immunohistochemistry was carried out in each specimen.

Results

The mean NA after PDT was significantly lower than that before PDT in the nonrecurrent group. However, there was no significant difference in mean NA before and after PDT in the recurrent group. There were no significance differences in NACV before and after PDT in either the nonrecurrent or recurrent group. Furthermore, the PCNA labelling indices of the specimens after PDT was significantly lower than that before PDT in both the nonrecurrent and the recurrent group.

Conclusions

Mean nuclear area in the biopsy specimen after photodynamic therapy is likely to be a predictive marker for the recurrence of oral squamous cell carcinoma or epithelial dysplasia subjected to photodynamic therapy, while coefficient of variation of the nuclear area and proliferating cell nuclear antigen labelling indices are less helpful in predicting the recurrence of such lesions.

Polymeric micelle nanoparticles for photodynamic treatment of head and neck cancer cells

Objective: To encapsulate 5,10,15,20-tetrakis( meso-hydroxyphenyl)porphyrin (mTHPP), a photosensitizer, into polymeric micelles; characterize the micelles; and test in vitro photodynamic therapy efficacy against human head and neck cancer cells.

Study Design: A nanoparticle design, fabrication, and in vitro testing study.

Setting: Polymer chemistry laboratory.

Subjects and Methods: Micelles encapsulating mTHPP were produced, and micellar size was measured. Ultraviolet visible spectra and fluorescence spectroscopy were used to characterize the mTHPP-loaded micelles. In vitro cell culture using HSC-3 and HN-5 cancer cells was performed to test the photodynamic therapy efficacy of the micelles using confocal microscopy and method of transcriptional and translational (MTT) assay.

Results: mTHPP was encapsulated with high loading efficiency (> 85%) and density (up to 17%) into micelles. Micelle size was 30.6 ± 3.3 nm by transmission electron microscopy and 30.8 ± 0.6 nm by dynamic light scattering. The absorption maximum for each sample was 418 nm, and fluorescent spectroscopy revealed quenching with maximal fluorescence at five percent loading. Significant cytotoxicity was observed with confocal microscopy when HSC-3 cells were treated with 10 percent mTHPP micelles, with 100 percent cytotoxicity within the zone of laser light exposure at 420 nm. Phototoxicity and dark toxicity against HSC-3 and HN-5 cells measured using the MTT assay with five and 10 percent loaded mTHPP micelles demonstrated greater than 90 percent cytotoxicity with photodynamic therapy and less than 10 percent dark toxicity at a micelle concentration of 25 μg/mL for both cell lines.

Conclusion: Micelles were able to encapsulate and solubilize mTHPP at high loading densities with uniform size distribution. These micelles exhibit fluorescence and photodynamic therapy mediated cytotoxicity against head and neck cancer cells in vitro.

Photodynamic therapy of head and neck cancers

Over 1,500 patients have been treated with PDT using Photofrin, HPD, ALA, or Foscan for head and neck cancers. These patients include a mixture of presentations including primary, recurrent, and metastatic lesions. The predominant histology is squamous cell carcinoma, but other histologies treated include mucosal melanoma, Kaposi's sarcoma, adenocarcinoma, metastatic breast carcinoma, and adenoid cystic carcinoma. Several multi-institutional phase II clinical trials evaluating PDT treatment of head and neck cancers have demonstrated the efficacy of this minimally invasive therapy in the treatment of early oropharyngeal primary and recurrent cancers as well as the palliative treatment of refractory head and neck cancers. Patients with early stage cancers or early recurrences in the oral cavity and larynx (Cis, T1, T2) tend to have an excellent response to PDT. Of 518 patients treated with Cis, T1, or T2 cancers of the oral cavity, larynx, pharynx, and nasopharynx, 462 (89.1%) obtained a complete clinical response after one PDT treatment. Laryngeal cancers, comprising 171 patients in this group, obtained a durable complete response rate of 89% with up to a 16-year follow-up. Photodynamic therapy is as effective as conventional therapies for the treatment of early (Cis, T1, T2) squamous cell cancers of the head and neck. It is also a promising therapy to be used in association with surgery to increase tumor-free margins and therefore increase cure rates.

Photofrin photodynamic therapy: 2.0 mg/kg or not 2.0 mg/kg that is the question

Photodynamic therapy (PDT) is an innovative minimally invasive therapy that has great potential for both tumor ablation and normal tissue preservation. However, while in recent years the standards of surgery, radiation and chemotherapy have dramatically improved in terms of outcomes and morbidity, the same cannot be said of PDT in general and Photofrin((R))-based PDT in particular. As currently practiced PDT dosimetry has not really improved tumor ablation and diminished side effects over reports from two decades ago. We critically examine the clinical variables available for PDT dosimetry and conclude that the simple maneuver of diminishing drug dose, with an appropriate increase in light dose, can enhance disease control with a significantly lower risk of morbidity. This conclusion should also be applicable to most systemically introduced photosensitizer.

Temoporfin-loaded invasomes: development, characterization and in vitro skin penetration studies

Temoporfin (mTHPC) is a highly hydrophobic second generation photosensitizer with low percutaneous penetration. In order to enhance its percutaneous penetration it was necessary to develop a mTHPC-loaded drug carrier system for enhanced skin delivery. mTHPC-loaded invasomes were developed, characterized and investigated for the in vitro percutaneous penetration of mTHPC into abdominal human skin using Franz diffusion cells. mTHPC-loaded invasomes were prepared using non-hydrogenated soybean lecithin (10% w/v), ethanol (3.3% w/v) and a mixture of terpenes (0.5 and 1% w/v). The invasomes obtained were of a sufficiently small particle size (<150 nm) and polydispersity index (<0.3). The particle size of invasomes increased following an increase in the amount of terpenes in the invasomes. All invasomes possessed a negative surface charge. The vesicles appeared to be unilamellar and oligolamellar, spherical and oval in shape. An interesting phenomenon was the finding that with increasing the amount of terpenes, the number of deformed vesicles in the dispersion increased. In vitro skin penetration data revealed that the invasome dispersion with 1% of the mixture of terpenes showed a significantly enhanced deposition (p<0.05) of the drug in the SC compared to liposomes without terpenes and the ethanolic solution.

Development and characterization of novel photosensitizer : scFv conjugates for use in photodynamic therapy of cancer

Photodynamic therapy (PDT) is becoming an evermore useful tool in oncology but is frequently limited by side-effects caused by a lack of targeting of the photosensitizer. This problem can often be circumvented by the conjugation of photosensitizers to tumour-specific monoclonal antibodies. An alternative is the use of single chain (sc) Fv fragments which, whilst retaining the same binding specificity, are more efficient at penetrating tumour masses because of their smaller size; and are more effectively cleared from the circulation because of the lack of an Fc domain. Here we describe the conjugation of two isothiocyanato porphyrins to colorectal tumour-specific scFv, derived from an antibody phage display library. The conjugation procedure was successfully optimized and the resulting immunoconjugates showed no loss of cell binding. In vitro assays against colorectal cell lines showed these conjugates had a selective photocytotoxic effect on cells. Annexin V and propidium iodide staining of treated cells confirmed cell death was mediated principally via an apoptotic pathway. This work suggests that scFv : porphyrin conjugates prepared using isothiocyanato porphyrins show promise for use as targeted PDT agents.

Advances in photodynamic therapy for the treatment of head and neck cancers

Photodynamic therapy (PDT) is an FDA-approved minimally invasive medical treatment modality that utilizes light in the presence of oxygen to activate photosensitizing agents that are relatively selectively concentrated in abnormal or neoplastic cells resulting in cell death. At the present time, PDT has been approved for clinical treatment in the United States, European Union, Canada, Russia, and Japan. In the United States, US Food and Drug administration approval has been given for the use of PDT in the treatment of Barrett's esophagus, obstructing esophageal carcinoma and early and obstructing tracheobronchial carcinoma using the photosensitizer Photofrin; actinic keratosis using the photosensitizer Levulan (aminolevulinic acid); and macular degeneration using the photosensitizer BPD. In the EU the above noted indications have also been approved in addition to the treatment of early head and neck cancers and palliative treatment of head and neck cancer using the photosensitizer Foscan; and treatment of basal and squamous cell skin cancers using the photosensitizer Metvix.