Photodynamic therapy (PDT) utilizing Photofrin is proving to be effective for the treatment
of early stage lung cancers. The effect of PDT utilizing YAG-OPO laser as new
light source was evaluated in 26 patients (29 lesions) with early stage lung cancers. YAG-OPO
laser is solid state tunable laser which is easy to change wavelength between 620 and
670 nm exciting various kinds of photosensitizers. Moreover, YAG-OPO laser is more reliable,
smaller and has less consumables than argon-dye laser or excimer-dye laser. As
the result of PDT with YAG-OPO laser, complete remission (CR) was obtained in 82.6%
of the 29 lesions, partial remission (PR) in 13.8% and no change (NC) was obtained in
3.4%. We conclude that PDT utilizing YAG-OPO laser is efficacious in the treatment
of early stage lung cancers and can achieve complete remission.
Photodynamic therapy (PDT) is not always effective as an anticancer treatment, therefore, PDT is combined with other anticancer agents for improved efficacy. The combination of dasatinib and PDT with the silicone phthalocyanine photosensitizer Pc 4 was assessed for increased killing of SCCVII mouse squamous cell carcinoma cells, a preclinical model of head and neck squamous cell carcinoma, using apoptotic markers and colony formation as experimental end-points. Because each of these treatments regulates the metabolism of the sphingolipid ceramide, their effects on mRNA levels of ceramide synthase, a ceramide-producing enzyme, and the sphingolipid profile were determined. PDT + dasatinib induced an additive loss of clonogenicity. Unlike PDT alone or PDT + dasatinib, dasatinib induced zVAD-fmk-dependent cell killing. PDT or dasatinib-induced caspase-3 activation was potentiated after the combination. PDT alone induced mitochondrial depolarization, and the effect was inhibited after the combination. Annexin V+ and propidium iodide+ cells remained at control levels after treatments. In contrast to PDT alone, dasatinib induced upregulation of ceramide synthase 1 mRNA, and the effect was enhanced after the combination. Dasatinib induced a modest increase in C20:1-and C22-ceramide but had no effect on total ceramide levels. PDT increased the levels of 12 individual ceramides and total ceramides, and the addition of dasatinib did not affect these increases. PDT alone decreased substantially sphingosine levels and inhibited the activity of acid ceramidase, an enzyme that converts ceramide to sphingosine. The data suggest that PDT-induced increases in ceramide levels do not correlate with ceramide synthase mRNA levels but rather with inhibition of ceramidase. Cell killing was zVAD-fmk-sensitive after dasatinib but not after either PDT or the combination and enhanced cell killing after the combination correlated with potentiated caspase-3 activation and upregulation of ceramide synthase 1 mRNA but not the production of ceramide. The data imply potential significance of the combination for cancer treatment.
apoptosis; ceramide; ceramide synthase; ceramidase; dasatinib; PDT; sphingolipids; sphingosine
Conventional cancer therapy including surgery, radiation, and chemotherapy often are physically debilitating and largely ineffective in previously treated patients with recurrent head and neck squamous cell carcinoma (SCC). A natural photochemical, hypericin, could be a less invasive method for laser photodynamic therapy (PDT) of these recurrent head and neck malignancies. Hypericin has powerful photo-oxidizing ability, tumor localization properties, and fluorescent imaging capabilities as well as minimal dark toxicity. The current study defined hypericin PDT in vitro with human SCC cells before the cells were grown as tumor transplants in nude mice and tested as a model for hypericin induced tumor fluorescence and PDT via laser fiberoptics.
SNU squamous carcinoma cells were grown in tissue culture, detached from monolayers with trypsin, and incubated with 0.1 μg to 10 μg/ml of hypericin before exposure to laser light at 514, 550, or 593 nm to define optimal dose, time, and wavelength for PDT of tumor cells. The SCC cells also were injected subcutaneously in nude mice and grown for 6–8 weeks to form tumors before hypericin injection and insertion of fiberoptics from a KTP532 surgical laser to assess the feasibility of this operating room instrument in stimulating fluorescence and PDT of tumors.
In vitro testing revealed a hypericin dose of 0.2–0.5 μg/ml was needed for PDT of the SCC cells with an optimal tumoricidal response seen at the 593 nm light absorption maximum. In vivo tumor retention of injected hypericin was seen for 7 to10 days using KTP532 laser induced fluorescence and biweekly PDT via laser fiberoptics led to regression of SCC tumor transplants under 0.4 cm2 diameter, but resulted in progression of larger size tumors in the nude mice.
In this preclinical study, hypericin was tested for 514–593 nm dye laser PDT of human SCC cells in vitro and for KTP532 surgical laser targeting of SCC tumors in mice. The results suggest hypericin is a potent tumor imaging agent using this surgical laser that may prove useful in defining tumor margins and possibly in sterilizing post-resection margins. Deeply penetrating pulsed infrared laser emissions will be needed for PDT of larger and more inaccessible tumors.
Photodynamic therapy (PDT) is a promising cancer treatment. PDT uses the affinity of photosensitizers to be selectively retained in malignant tumors. When tumors, pretreated with the photosensitizer, are irradiated with visible light, a photochemical reaction occurs and tumor cells are destroyed. Oxygen molecules in the metastable singlet delta state O2(1Δ) are believed to be the species that destroys cancerous cells during PDT. Monitoring singlet oxygen produced by PDT may lead to more precise and effective PDT treatments. Our approach uses a pulsed diode laser-based monitor with optical fibers and a fast data acquisition system to monitor singlet oxygen during PDT. We present results of in vitro singlet oxygen detection in solutions and in a rat prostate cancer cell line as well as PDT mechanism modeling.
photodynamic therapy; singlet oxygen; light dosimetry
Photodynamic therapy (PDT) is an ablative treatment leading to intracellular photoexcitation and injury. A total of 15 patients with superficial esophageal squamous cell carcinoma (ESCC) without metastasis underwent PDT and 48–72 h after intravenous Photofrin, the patients were treated with a 630-nm excimer dye laser. A total of 13 patients had local tumor recurrence after definitive chemoradiotherapy (CRT) consisting of 5-fluorouracil (5-FU) and cisplatin (CDDP). Of 6 patients, 5 had submucosal ESCC and were treated with S-1. Complete reponse was achieved by 11 patients with initial PDT, but 2 had recurrences. The recurrent/residual tumors were successfully treated with repeated PDT. Two patients with intramucosal ESCC succumbed due to metastatic disease, but 11 patients were disease-free. The 5 patients treated with S-1 remained alive despite submucosal ESCC. PDT was applied to human ESCC cells in vitro in the presence or absence of 5-FU or CDDP. The combination of PDT with 5-FU or CDDP resulted in enhanced cytotoxic effects, thereby reducing the effective dosage of each drug. PDT is a promising treatment option for selected ESCC cases, particularly for local recurrence following CRT. Our experience suggests that PDT is more effective when combined with chemotherapy.
photodynamic therapy; esophageal squamous cell carcinoma; chemoradiotherapy; 5-fluorouracil
Photodynamic therapy (PDT) was discovered over one hundred years ago when it was observed that certain dyes could kill microorganisms when exposed to light in the presence of oxygen. Since those early days, PDT has mainly been developed as a cancer therapy and as a way to destroy proliferating blood vessels. However, recently it has become apparent that PDT may also be used as an effective antimicrobial modality and a potential treatment for localized infections. This review discusses the similarities and differences between the application of PDT for the treatment of microbial infections and for cancer lesions. Type I and type II photodynamic processes are described, and the structure-function relationships of optimal anticancer and antimicrobial photosensitizers are outlined. The different targeting strategies, intracellular photosensitizer localization, and pharmacokinetic properties of photosensitizers required for these two different PDT applications are compared and contrasted. Finally, the ability of PDT to stimulate an adaptive or innate immune response against pathogens and tumors is also covered.
antitumor agents; antimicrobial agents; cancer; photodynamic therapy; sensitizers
Pulsed dye laser (PDL) is a commonly utilized treatment for port wine stain birthmarks (PWS) in the United States; however, results are variable and few patients achieve complete removal. Photodynamic therapy (PDT) is commonly used in China, but treatment associated photosensitivity lasts several weeks and scarring may occur. We propose an alternative treatment option, combined PDT+PDL and performed a proof-of-concept preliminary clinical trial.
Subjects with non-facial PWS were studied. Each subject had four test sites: control, PDL alone, PDT alone (benzoporphyrin derivative monoacid ring A photosensitizer with 576 nm light), and PDT+PDL. Radiant exposure time for PDT was increased in increments of 15 J/cm2. Authors evaluated photographs and chromametric measurements before and 12 weeks post-treatment.
No serious adverse events were reported; epidermal changes were mild and self-limited. No clinical blanching was noted in control or PDT-alone sites. At PDT radiant exposures of 15 and 30 J/cm2, equivalent purpura and blanching was observed at PDL and PDT+PDL sites. At PDT radiant exposures over 30 J/cm2, greater purpura was noted at PDT+PDL sites as compared to PDL alone. Starting at 75 J/cm2, improved blanching was noted at PDT+PDL sites.
Preliminary results indicate that PDT+PDL is safe and may offer improved PWS treatment efficacy. Additional studies are warranted.
Port wine stain birthmarks; pulsed dye laser; photodynamic therapy; vascular birthmarks
The time course of serum PSA response to photodynamic therapy (PDT) of prostate cancer was measured.
Seventeen patients were treated in a Phase I trial of motexafin lutetium-PDT. PDT dose was calculated in each patient as the product of the ex vivo-measured pre-PDT photosensitizer level and the in situ-measured light dose. Serum PSA level was measured within two months prior to PDT (baseline), and at day 1; weeks 1-3; months 1, 2 and 3; months 4-6 and months 7-11 after PDT.
At 24h after PDT, serum PSA increased by 98±36% (mean ± SE) relative to baseline levels (p=0.007). When patients were dichotomized based on median PDT dose, those who received high PDT dose demonstrated a 119±52% increase in PSA compared to a 54±27% increase in patients treated at low PDT dose. Patients treated with high vs. low PDT dose demonstrated a median biochemical delay of 82 vs. 43 days (p=0.024), with biochemical delay defined as the length of time between PDT and a nonreversible increase in PSA to a value ≥baseline.
Results show PDT to induce large, transient increases in serum PSA levels. Patients who experienced high PDT dose demonstrated greater short-term increase in PSA and a significantly more durable PSA response (biochemical delay). These data strongly promote the need for individualized delivery of PDT dose and assessment of treatment effect in PDT of prostate cancer. Information gained from such patient-specific measurements could facilitate the introduction of multiple PDT sessions in patients who would benefit.
motexafin lutetium; prostate; PSA; PDT dose; photosensitizer concentration
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.
Oral lichen planus; Photodynamic therapy
Cancer, when detected at an early stage, has a very good probability of being eradicated by
surgery or radiotherapy. However, less aggressive treatments also tend to provide high rates
of cure without the side effects of radical therapy. We report on the results of our clinical
experience with photodynamic therapy (PDT) for the treatment of early carcinomas in the
upper aerodigestive tract, the esophagus, and the tracheobronchial tree. Sixty-four patients
with 101 squamous cell carcinomas were treated with three different photosensitizers:
hematoporphyrin derivative (HPD), Photofrin II, and tetra (m-hydroxyphenyl)chlorin
(mTHPC). Seventy-seven (76%) tumors showed a complete rsponse with no recurrence
after a mean follow-up period of 27 months. There was no significant difference in terms of
cure rates among the three dyes. However, mTHPC has a stronger phototoxicity and induces
a shorter skin photosensitization than either of the other photosensitizers. There were eight
major complications: three esophagotracheal fistulae after illumination with red light in the
esophagus, two esophageal stenoses following 360° circumferential irradiation, and three
bronchial stenoses. Illumination with the less penetrating green light and the use of a 180° or
240° windowed cylindrical light distributor render the risk of complications in the esophagus
essentially impossible, without reducing the efficacy of the treatment. Therefore, PDT may be
considered as a safe and effective treatment for early carcinomas of the upper aerodigestive
tract, the esophagus, and the tracheobronchial tree.
Photodynamic therapy (PDT) is a promising cancer treatment modality that involves the interaction of the photosensitizer, molecular oxygen and light of specific wavelength to destroy tumor cells. Treatment induced hypoxia is one of the main side effects of PDT and efforts are underway to optimize PDT protocols for improved efficacy. The aim of this study was to investigate the anti-tumor effects of PDT plus Erbitux, an angiogenesis inhibitor that targets epidermal growth factor receptor (EGFR), on human bladder cancer model. Tumor-bearing nude mice were assigned to four groups that included control, PDT, Erbitux and PDT plus Erbitux and tumor volume was charted over 90-day period.
Our results demonstrate that combination of Erbitux with PDT strongly inhibits tumor growth in the bladder tumor xenograft model when compared to the other groups. Downregulation of EGFR was detected using immunohistochemistry, immunofluorescence and western blotting. Increased apoptosis was associated with tumor inhibition in the combination therapy group. In addition, we identified the dephosphorylation of ErbB4 at tyrosine 1284 site to play a major role in tumor inhibition. Also, at the RNA level downregulation of EGFR target genes cyclin D1 and c-myc was observed in tumors treated with PDT plus Erbitux.
The combination therapy of PDT and Erbitux effectively inhibits tumor growth and is a promising therapeutic approach in the treatment of bladder tumors.
Background and Objective: Photodynamic therapy (PDT) treats malignant tumors using
photosensitizers and light. We employed a new pulse laser as the excitation light source
for PDT, i.e. an optical parametric oscillator (OPO) system pumped by a Q-switched
Nd:YAG laser, because it provides extremely high peak power.
Study Design/Materials and Methods: The effects of PDT using the photosensitizer
Photofrin® and the new laser were evaluated in 12 patients with early gastric cancer.
Results: Complete responses (CR) were obtained in 75% of 12 assessable patients,
CR was observed in all cases with mucosal carcinoma (response rate 100%).
Regarding toxicity, mild photosensitivity was seen in one case and it lasted several
weeks. The other major side effect was decrease of total protein, which was observed in
six patients (40%), lasting several months. There were no serious abnormalities in symptoms
or laboratory tests.
Conclusion: We conclude that the YAG-OPO laser is suitable as an excitation light
source for PDT.
BACKGROUND: Aminolaevulinic acid (ALA) is an endogenous substrate in the haem biosynthetic pathway. Protoporphyrin IX (PPIX), the immediate haem precursor in the pathway, has photoexcitable properties. Exogenous ALA has been used previously as a precursor agent in photodynamic therapy (PDT). Its main advantage is a short half-life and hence reduced incidence of skin photosensitivity. ALA can be toxic, however, causing, for example, transient increases in liver enzyme concentrations when given systemically and this may be dose related. AIM: To assess whether accumulation of PPLX and ultimately the efficacy of PDT could be improved by modulating both ends of the haem biosynthetic pathway. METHODS: Gastric cancer cells (MKN 28) were incubated with ALA (0-1000 mumolar) and desferrioxamine (0-800 mumolar) for 24 hours before exposure to argon-pumped dye laser (630 nm) at different energy levels (0-40 J/cm2). Cell viability was assessed by use of the methyl-tetrazolium (MTT) assay four hours after exposure to light. RESULTS: Total PPIX accumulation increased linearly with increasing extracellular concentrations of ALA up to 1 mmolar (r = 0.973, p < 0.005). Adding 200 molar of desferrioxamine trebled PPIX accumulation over the same period of incubation. Cell viability after exposure to light decreased with low doses (0-30 mumolar) of desferrioxamine (r = 0.976, p = 0.024). However, higher doses of desferrioxamine (more than 40 molar) seemed to confer a protective effect against PDT. CONCLUSION: PDT using ALA can be improved by removal of available iron with desferrioxamine. The reason for the protective effect of desferrioxamine seen at higher doses is not clear.
Photodynamic therapy (PDT) is a novel treatment modality, which produces local tissue necrosis with laser light following the prior administration of a photosensitizing agent. Radachlorin® has recently been shown to be a promising PDT sensitizer. In order to elucidate the antitumor effects of PDT using Radachlorin® on cervical cancer, growth inhibition studies on a HPV-associated tumor cell line, TC-1 cells in vitro and animals with an established TC-1 tumor in vivo were determined.
Materials and Methods
TC-1 tumor cells were exposed to various concentrations of Radachlorin® and PDT, with irradiation of 12.5 or 25 J/cm2 at an irradiance of 20 mW/cm2 using a Won-PDT D662 laser at 662 nm in vitro. C57BL/6 mice with TC-1 tumor were injected with Radachlorin® via different routes and treated with PDT in vivo. A growth suppression study was then used to evaluate the effects at various time points after PDT.
The results showed that irradiation of TC-1 tumor cells in the presence of Radachlorin® induced significant cell growth inhibition. Animals with established TC-1 tumors exhibited significantly smaller tumor sizes over time when treated with Radachlorin® and irradiation.
PDT after the application of Radachlorin® appears to be effective against TC-1 tumors both in vitro and in vivo.
Radachlorin®; Photodynamic therapy (PDT); Cervical cancer; TC-1 cell
Background and Objectives
Photodynamic therapy (PDT) mediated with Tookad (Pd-bacteriopheophorbide, WST09) was investigated pre-clinically as part of a program to develop an alternative modality for treating prostate cancer.
Study Design/Materials and Methods
Spontaneous canine prostate cancer and normal canine prostate were used as the animal models. Interstitial PDT was performed by IV infusion of the photosensitizer and irradiating the prostates with a diode laser (763 nm). The prostates were harvested 1-week post-PDT and subjected to histopathologic examinations. The effects of the drug doses and light doses were studied for one- and two-session PDT. Pharmacokinetics were studied using HPLC assay. The feasibility of using perfusing CT scans for assessing PDT lesions was also evaluated.
Tookad is a vascular-acting drug and clears rapidly from the circulation. Tookad-PDT-induced lesions, in both normal and cancerous prostates, were characterized by marked hemorrhagic necrosis.
Tookad-PDT is very effective in ablating prostatic tissue through its vascular effects.
photodynamic therapy; prostate cancer; Tookad; pharmacokinetics; vascular effects
Photodynamic therapy (PDT) utilizing Photofrin is proving to be effective for the treatment of early stage lung cancer. However, wider clinical applications of Photofrin as a photosensitizer for various cancers are hampered by potentially serious and prolonged skin photosensitivity. To prevent these side effects and reduce the hospitalization period, we recently gave reduced doses of Photofrin by bronchial arterial infusion. Five patients with endoscopically evaluated minimally invasive carcinoma of the lung were given 0.7 mg/kg of Photofrin by bronchial arterial infusion 48 hr before PDT. Complete remission was obtained in all 5 cases and no case showed skin photosensitivity when exposed to sunlight under careful surveillance at one week after PDT.
Photodynamictherapy (PDT) uses a drug called a photosensitizer that is excited by irradiation with a laser light of a particular wavelength, which generates reactive singlet oxygen that damages the tumor cells. The photosensitizer and light are inert; therefore, systemic toxicities are minimized in PDT. The synthesis of novel PDT drugs and the use of nanosized carriers for photosensitizers may improve the efficiency of the therapy and the delivery of the drug. In this study, we formulated two nanoparticles with and without a targeting ligand to encapsulate phthalocyanines 4 (Pc 4) molecule and compared their biodistributions. Metastatic human head and neck cancer cells (M4e) were transplanted into nude mice. After 2–3 weeks, the mice were injected with Pc 4, Pc 4 encapsulated into surface coated iron oxide (IO-Pc 4), and IO-Pc 4 conjugated with a fibronectin-mimetic peptide (FMP-IO-Pc 4) which binds specifically to integrin β1. The mice were imaged using a multispectral camera. Using multispectral images, a library of spectral signatures was created and the signal per pixel of each tumor was calculated, in a grayscale representation of the unmixed signal of each drug. An enhanced biodistribution of nanoparticle encapsulated PDT drugs compared to non-formulated Pc 4 was observed. Furthermore, specific targeted nanoparticles encapsulated Pc 4 has a quicker delivery time and accumulation in tumor tissue than the non-targeted nanoparticles. The nanoparticle-encapsulated PDT drug can have a variety of potential applications in cancer imaging and treatment.
Multispectral imaging; iron oxide; theranostic agent; head and neck cancer; optical imaging; nanoparticles; phthalocyanine 4 (Pc 4); photodynamic therapy; photosensitizers; nanomedicine; pharmaceutical nanocarriers; drug delivery; drug-encapsulation
Progress of photodynamic therapy (PDT) in gastric cancer and the clinical outcome are
described in this paper. (1) We included the whole lesion and a 5 mm margin in the field for
irradiation. Marking by injection of India-ink showing the irradiation field was performed
beforehand. (2) We established the standard light dose to be 90 J/cm2 for an argon dye
laser and 60 J/cm2 for a pulse wave laser. (3) The size of cancerous lesion curable by PDT
was expanded from 3 cm in diameter, i.e. 7 cm2 in area to 4 cm in diameter, i.e. 13 cm2 by
employing a new excimer dye laser model, which could emit 4mJ/pulse with 80 Hz pulse
frequency. (4) The depth of cancer invasion which could be treated by PDT was increased from
about 4 mm, i.e. the superficial part of the submucosal layer (SM-1) to more than 10 mm in
depth, i.e. the proper muscular layer. These improvements owe much to the pulse laser, the
photodynamic action induced by which permits deeper penetration than that of a continuous
wave laser. (5) We employed a side-viewing fiberscope for gastric PDT to irradiate the lesion
from an angle of 90°. (6) We designed a simple cut quartz fiber for photoradiation with a spiral spring thickened toward the end. (7) We developed an endoscopic device for photoradiation in
PDT which achieves accurate and efficient irradiation. As a result of these improvements a
higher cure rate was obtained even with a lower light dose of irradiation.
Photodynamic therapy (PDT) is a relatively new therapy that has shown promise for treating various cancers in both preclinical and clinical studies. The present study evaluated the potential use of PET with radiolabeled choline to monitor early tumor response to PDT in animal models.
Two human prostate cancer models (PC-3 and CWR22) were studied in athymic nude mice. A second-generation photosensitizer, phthalocyanine 4 (Pc 4), was delivered to each animal by a tail vein injection 48 h before laser illumination. Small-animal PET images with 11C-choline were acquired before PDT and at 1, 24, and 48 h after PDT. Time–activity curves of 11C-choline uptake were analyzed before and after PDT. The percentage of the injected dose per gram of tissue was quantified for both treated and control tumors at each time point. In addition, Pc 4-PDT was performed in cell cultures. Cell viability and 11C-choline uptake in PDT-treated and control cells were measured.
For treated tumors, normalized 11C-choline uptake decreased significantly 24 and 48 h after PDT, compared with the same tumors before PDT (P < 0.001). For the control tumors, normalized 11C-choline uptake increased significantly. For mice with CWR22 tumors, the prostate-specific antigen level decreased 24 and 48 h after PDT. Pc 4-PDT in cell culture showed that the treated tumor cells, compared with the control cells, had less than 50% 11C-choline activity at 5, 30, and 45 min after PDT, whereas the cell viability test showed that the treated cells were viable longer than 7 h after PDT.
PET with 11C-choline is sensitive for detecting early changes associated with Pc 4-PDT in mouse models of human prostate cancer. Choline PET has the potential to determine whether a PDT-treated tumor responds to treatment within 48 h after therapy.
small-animal PET; choline molecular imaging; photodynamic therapy (PDT); prostate cancer; tumor response
Laser endoscopic surgery, especially the effectiveness of photodynamic therapy (PDT) using
Photofrin as a photosensitizer, has now achieved a status as effective treatment modality for
lung cancer. Twenty-six lung cancer patients received the preoperative PDT for the purpose of
either reducing the extent of resection or increasing operability. Bronchoscopical PDT is
performed with topical anesthesia approximately 48 h after the intravenous injection of
2.0 mg/kg body weight of Photofrin. Operation was performed 2–9 weeks after initial PDT. The initial purpose of PDT, i.e. either to reduce the extent of resection or convert inoperable
disease to operable status, was achieved in 22 out of 26 patients treated. The survival rate of T3
(main bronchus invasion) cases treated by surgery alone increased significantly from 50.9% to
60.0% with the application of preoperative PDT. This remarkable result may imply that this
new option of PDT as preoperative laser irradiation may contribute to the management of
advanced lung malignancy.
To investigate the ultrastructural pathogenesis of photodynamic therapy (PDT) for the experimental corneal neovascularization (CNV) by Hematoporphyrin Derivate (HPD) as photosensitizer and Argon laser as light source.
Experimental CNV models were induced in 7 white rabbits using alkali burn. Six weeks after models establishment, animals with CNV were injected with HPD intravenously, and 48 hours after the injection, 7 eyes were irradiated with argon laser (power 800mw, wavelength 514.5nm, spot diameter 200µm, exposure time 2ms). The irradiated CNV was observed by light microscopy and scanning electron microscopy.
Histopathological study indicated that there was a striking decrease in the number of the CNV, vascular endothelium became degeneration and necrosis, some vessels were atrophy and attenuated, and vessels cavity were blocked by some thrombosis. No obvious abnormal histopathological findings were noted in surrounding tissues.
The high precise action on CNV and minimal damage to surrounding tissues with PDT by HPD as photosensitizer suggested that PDT might be an effective and safe modality in the treatment of CNV.
corneal neovascularization; photodynamic therapy; histopathology
The effect of combining photodynamic therapy (PDT) and bioreductive drugs has been investigated using the RIF-1 experimental murine tumour. Light was delivered interstially to the tumour at 675 nm using a single optical fibre attached to an argon-ion dye laser. The photosensitizer was disulphonated aluminium phthalocyanine (AlS2Pc) and the bioreductive drugs were the dual function nitroimidazole RSU1069 and its pro-drug RB6145. Varying the time between administration of the photosensitizer and light delivery (TL) from 30 min to 24 h had little influence on the extent of the anti-tumour effect of PDT alone, as measured by the regrowth delay endpoint. When the bioreductive drug was included in the treatment, administered 20 min before light irradiation, regrowth delay was greatly increased. The effectiveness of the combined treatment was optimum for short values of TL (about 1 h). Fluorescence microscopy was used to investigate the distribution of the photosensitizer within the tumours. This showed that the compound was mainly confined to the tumour vasculature over the first few hours post-treatment. The high efficacy of the combined treatment of PDT and bioreductive drugs for short values of TL suggest that photodynamic action, during the period when the photosensitizer AlS2Pc is confined to the vasculature, enhances the severity of tumour hypoxia which is sufficient to induce activation of the bioreductive drugs.
The effectiveness of photodynamic therapy (PDT) for cancer treatment correlates with apoptosis. We previously observed that the knockdown of ceramide synthase 6, an enzyme from the de novo sphingolipid biosynthesis pathway, is associated with marked reduction in C18-dihydroceramide and makes cells resistant to apoptosis post-PDT. Down-regulation of ceramide synthase 1 (CERS1) can also render cells resistant to anticancer drugs.
To explore the impact of CERS1 knockdown on apoptosis and the sphingolipid profile, post-PDT, with the silicone phthalocyanine Pc 4, in a human head and neck squamous carcinoma cell line.
Materials and Methods
Besides siRNA transfection and PDT treatment, the following methods were used: immunoblotting for protein expression, mass spectrometry for sphingolipid analysis, spectroflurometry and flow cytometry for apoptosis detection, and trypan blue assay for cell viability evaluation.
CERS1 knockdown led to inhibition of PDT-induced caspase 3-like (DEVDase) activation, of apoptosis and cell death. CERS1 knockdown was associated with global and selective decreases in ceramides and dihydroceramides, in particular C18-, C18:1- and C20-ceramide post-PDT.
Our novel findings are consistent with the notion that CERS1 regulates apoptotic resistance to PDT, partly via C18- and C20-ceramide, and that CERS1 is a molecular target for controlling resistance to PDT.
Apoptosis; ceramide; ceramide synthase 1; dihydroceramide; PDT; sphingolipids; head and neck squamous carcinomas cells UM-SCC-22A
Photodynamic therapy (PDT) employs the triple combination of photosensitizers, visible light and ambient oxygen. When PDT is used for cancer, it has been observed that both arms of the host immune system (innate and adaptive) are activated. When PDT is used for infectious disease, however, it has been assumed that the direct antimicrobial PDT effect dominates. Murine arthritis caused by methicillin-resistant Staphylococcus aureus in the knee failed to respond to PDT with intravenously injected Photofrin®. PDT with intra-articular Photofrin produced a biphasic dose response that killed bacteria without destroying host neutrophils. Methylene blue was the optimum photosensitizer to kill bacteria while preserving neutrophils. We used bioluminescence imaging to noninvasively monitor murine bacterial arthritis and found that PDT with intra-articular methylene blue was not only effective, but when used before infection, could protect the mice against a subsequent bacterial challenge. The data emphasize the importance of considering the host immune response in PDT for infectious disease.
bacterial arthritis; bioluminescence imaging; methicillin-resistant Staphylococcus aureus; methylene blue; neutrophils; photodynamic therapy; Photofrin®; preventative PDT
The lack of specific delivery of photosensitizers (PSs), represents a significant limitation of photodynamic therapy (PDT) of cancer. The biomarker prostate-specific membrane antigen (PSMA) has attracted considerable attention as a target for imaging and therapeutic applications for prostate cancer. Although recent efforts have been made to conjugate inhibitors of PSMA with imaging agents, there have been no reports on photosensitizer-conjugated PSMA inhibitors for targeted PDT of prostate cancer. The present study focuses on the use of a PSMA inhibitor-conjugate of pyropheophorbide-a (Ppa-conjugate 2) for targeted PDT to achieve apoptosis in PSMA+ LNCaP cells.
Confocal laser scanning microscopy with a combination of nuclear staining and immunofluorescence methods were employed to monitor the specific imaging and PDT-mediated apoptotic effects on PSMA-positive LNCaP and PSMA-negative (PC-3) cells.
Our results demonstrated that PDT-mediated effects by Ppa-conjugate 2 were specific to LNCaP cells, but not PC-3 cells. Cell permeability was detected as early as 2 h by HOE33342/PI double-staining, becoming more intense by 4 h. Evidence for the apoptotic caspase cascade being activated was based on the appearance of PARP p85 fragment. TUNEL assay detected DNA fragmentation 16 h post-PDT, confirming apoptotic events.
Cell permeability by HOE33342/PI double-staining as well as PARP p85 fragment and TUNEL assays confirm cellular apoptosis in PSMA+ cells when treated with PS-inhibitor conjugate 2 and subsequently irradiated. It is expected that the PSMA targeting small-molecule of this conjugate can serve as a delivery vehicle for PDT and other therapeutic applications for prostate cancer.
PSMA; targeted photodynamic therapy; pyropheophorbide-a; prostate cancer; apoptosis