血卟啉单甲醚对人肝细胞癌细胞系HepG_2的光动力杀伤效应

目的 光动力治疗是一种有效的局部肿瘤治疗手段.包括光敏剂的注射及激光照射两部分;观察以HMME作为光敏剂,再辅以630nm二极管激光照射对人肝细胞癌细胞HepG_2的光动力杀伤效应.方法 应用MTT技术来检测HepG_2细胞的抑制率;应用AnnexinV/PI双染色流式细胞仪来检测凋亡细胞所占的百分比;两种方法被用来检测细胞凋亡,TUNEL及激光共聚焦显微镜摄片.结果 在体外PDT实验中,不同的激光能量及药物浓度对HepG_2细胞显示出了很强的细胞毒性(P<0.05),并且HMME主要以凋亡的形式介导HepG_2细胞死亡.结论 笔者的研究证明,应用HMME及二极管激光器可以诱导人肝细胞癌细胞系HepG_2发生凋亡.这种治疗手段对临床上的HCC病人有较好的临床前景.     

Critical parameters in the cytotoxicity of photodynamic therapy using a pulsed laser

. Photodynamic therapy (PDT) using a pulsed laser is becoming popular, but its cytotoxic effect is still not clear. We therefore studied the cytotoxicity of PDT using a pulsed laser by changing its irradiation parameters and compared the degrees of cytotoxicity with those of PDT using continuous-wave (CW) light sources. Mice renal cell carcinoma cells were incubated with PAD-S31, a water-soluble photosensitiser of which the excitation peak is 670 nm, and were then irradiated with either a tungsten lamp, a CW diode laser, or a nanosecond pulsed Nd:YAG laser-based optical parametric oscillator system. When the PAD-S31 concentration and total light dose were constant (12 μg/ml and 40 J/cm², respectively), the CW laser caused fluence rate-dependent decrease in cellular proliferation until the fluence rate reached 90 mW/cm², at which point inhibition of cellular proliferation was more than 80%. The cytotoxicity then became almost saturated at fluence rates of>90 mW/cm². On the other hand, inhibition of cellular proliferation in samples irradiated with the pulsed laser reached 80% even at the fluence rate of 15 mW/cm², and, interestingly, the cytotoxicity paradoxically decreased with increase in the fluence rate. Moreover, the cytotoxicity in the PDT using the pulsed laser depended on the repetition rate. The inhibition of cellular proliferation by PDT using 30-Hz irradiation was greater than that by PDT using 5-Hz irradiation when the same fluence rates were used. These results suggest that the efficacy of PDT using a pulsed laser depends considerably on fluence rate and repetition rate. Paper received 4 March 2002; accepted after revision 24 May 2002. Correspondence to: Yuji Morimoto, MD, PhD, Department of Medical Engineering, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. Tel: +81-42-995-1596; Fax: +81-42-996-5199; e-mail: moyan@interlink.or.jp     

Differences between cytotoxicity in photodynamic therapy using a pulsed laser and a continuous wave laser: study of oxygen consumption and photobleaching

Oxygen consumption at the targeted site has a significant effect on dosimetry in photodynamic therapy (PDT). However, oxygen consumption in PDT using a pulsed laser as a light source has not been clarified. We therefore investigated the dependence of cytotoxicity on the oxygen consumption and the photosensitizer photobleaching of PDT using a pulsed laser by comparing with that using a continuous wave (CW) laser. Mouse renal carcinoma cells (Renca) were incubated with a second-generation photosensitizer, PAD-S31. The cells were then irradiated with either a 670-nm nanosecond pulsed light from the 3rd harmonics of a Nd:YAG laser-pumped optical parametric oscillator with a peak fluence rate of ~1 MW/cm² at 30 Hz or a 670-nm CW diode laser with a total light dose of 40 J/cm². Regardless of laser source, cytotoxic effects exhibited cumulative dose responses to the photosensitizer ranging from 12 to 96 g/ml. However, cytotoxic effect of PDT using the pulsed light was significantly less than that using the CW light with the photosensitizer concentrations of 24 and 48 g/ml under identical fluence rates. During PDT, the cells exposed to the pulsed light consumed oxygen more slowly, resulting in a lower amount of oxygen consumption when compared with PDT using CW light. In accordance with oxygen consumption, the pulsed light induced significantly less photobleaching of the photosensitizer than the CW light did. These results indicate that the efficiency of PDT using pulsed light is less when compared with CW light, probably being related to suppressed oxygen consumption during the pulsed light irradiation.     

Effect of a newly synthesized Zn sulfophthalocyanine derivative on cell morphology,viability, proliferation,and cytotoxicity in a human lung cancer cell line (A549)

Photodynamic therapy (PDT) is a photochemotherapeutic process that is used for the treatment of cancer. Photofrin is the most widely used photosensitizer, however, the chemical composition of Photofrin is unclear and it has a low absorption in the therapeutic wavelength (600–900 nm). This factor has stimulated research in synthesis and testing of new photosensitizers. This in vitro study evaluated the effectiveness of a Zn sulfophthalocyanine (ZnPcS_mix) as a potential photosensitizer in the treatment of human lung cancer. Lung cancer cells (A549) were divided into four groups: group 1 was control cells receiving neither light nor drug; group 2 was light control for cells exposed to laser irradiation at a fluence of 4.98 J/cm²; group 3 was drug control for cells incubated with 15.8 μM photosensitizer and not exposed to laser irradiation, while group 4 was cells receiving the experimental treatment with 15.8 μM photosensitizer and irradiation with 4.98 J/cm². Laser irradiations were performed using a 636-nm diode laser with an output power of 110 mW at 4.98 J/cm². Changes in cellular responses were evaluated by cell morphology, viability, proliferation, and cytotoxicity. While control groups 1, 2, and 3 showed no changes in cell morphology, viability, proliferation, or cytotoxicity, group 4 receiving both photosensitizer and irradiation showed changes in cell morphology, a decrease in cell viability and proliferation, and an increase in cytotoxicity, cell death, and cell membrane damage. Irradiation or photosensitizer alone had no effect on the lung cancer cells since the cells remained viable and showed no evidence of damage. However, irradiation in the presence of a photosensitizer induced cell death.     

Selective occlusion of choroidal neovascularization by photodynamic therapy with a water-soluble photosensitizer, ATX-S10

BACKGROUND AND OBJECTIVE: To determine the optimal treatment parameters for selective occlusion of choroidal neovascularization (CNV) by photodynamic therapy (PDT) by using the photosensitizer ATX-S10 and a diode laser (wavelength = 670 nm). MATERIALS AND METHODS: Experimental CNV was induced in rat fundi by argon laser photocoagulation. The distribution of ATX-S10 in the chorioretina was analyzed by fluorescence microscopy, and the optimal treatment parameters for selective occlusion of CNV were investigated by changing the dosage and timing of laser irradiation. CNV closure and resulting damage of the surrounding tissue were documented by fluorescein angiography and light and electron microscopies. RESULTS: Fluorescence of ATX-S10 was observed to be localized in the vascular lumen of the retina and choroid within 5 min after dye injection and increased in intensity in CNV up to 2-6 h and decreased rapidly in normal tissue. Laser irradiation with radiant exposures of 7.4 J/cm2 applied immediately after dye injection or with 22.0 J/cm2 at 2-4 h later effectively occluded the induced CNV without causing significant damage to normal retinal capillaries and large choroidal vessels. CONCLUSIONS: PDT using ATX-S10 can selectively occlude CNV. ATX-S10 is a potentially useful photosensitizer for the treatment of CNV.     

Photodynamic therapy with PAD-S31, a new hydrophilic chlorin photosensitizer, in an orthotopic rat bladder tumor model

PURPOSE: PAD-S31 (13,17-bis (1-carboxypropion) carbamoylethyl-3-ethenyl-8-ethoxyiminoethylidene-7-hydroxy-2,7,12,18-tetramethyl-porphyrin sodium) (Photochemical Co., Ltd., Okayama, Japan), 1 of the latest second-generation photosensitizers, has hydrophilic characteristics and excitation wavelengths of around 670 nm. Using an orthotopic rat bladder tumor model we investigated the biodistribution of PAD-S31 and assessed the antitumor effects of photodynamic therapy (PDT) with PAD-S31. MATERIALS AND METHODS: An orthotopic rat bladder tumor was established by implanting AY-27 cells in the bladder wall. After intravenous PAD-S31 administration the accumulation of PAD-S31 in the tumor and normal bladder wall was investigated by a fluorometric technique. One or 3 hours after intravenous administration of PAD-S31 (5 mg/kg) bladder tumors in rats were transurethrally irradiated at 100 mW/cm with a light dose of 50 to 200 J/cm. The efficacy of PDT was evaluated 7 days later by observation with an ultrathin cystoscope and histopathological examination. RESULTS: The ratio of PAD-S31 concentration in tumor tissue to that in normal bladder wall was more than 1 at all time points and it achieved a maximum (more than 10) 150 to 240 minutes after PAD-S31 administration. All rats that were irradiated at 100 J/cm 3 hours after PAD-S31 administration showed more than 50% tumor destruction. When the light dose was more than 150 J/cm, more than half of the rats showed complete tumor eradication, of which the average size was 6 mm. CONCLUSIONS: We report that PDT using PAD-S31 is effective for destroying bladder tumors in an orthotopic rat model. These experimental results suggest that this therapy could be a clinically promising method for the treatment of patients with bladder cancer.     

Necrotic and apoptotic cell death of human malignant melanoma cells following photodynamic therapy using an amphiphilic photosensitizer,ATX-S10(Na)

BACKGROUND AND OBJECTIVES: To investigate the phototoxic effect on and cell death modes of human malignant melanoma cells following photodynamic therapy (PDT) using ATX-S10(Na), an amphiphilic photosensitizer. MATERIALS AND METHODS: Cultured human malignant melanoma cells were incubated in a medium containing various concentrations of ATX-S10(Na) and irradiated with a 670 nm wavelength diode laser. Phototoxicity was analyzed by a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay, and cell death modes were investigated by fluorescence microscopy using a Hoechst 33342-propidium iodide double-staining method as well as by static gel electrophoresis. The subcellular localization of ATX-S10(Na) and mitochondrial destabilization following PDT were observed by fluorescence microscopy. RESULTS: Higher phototoxicity was obtained with higher dye and/or laser doses. Most of the dead cells appeared apoptotic with dye and irradiation doses that induced less than 70% cytotoxicity. In contrast, most of them appeared necrotic with doses that induced 99% cytotoxicity. Cells receiving PDT showed disturbances of mitochondrial trans-membrane potential, although the primary site of ATX-S10(Na) accumulation was in lysosomes. CONCLUSIONS: ATX-S10(Na) has a phototoxic effect on malignant melanoma cells and, therefore, potential as a photosensitizing agent for PDT designed to kill these cells. Apoptotic pathways may be activated via mitochondrial destabilization following the damage of lysosomes by PDT. Further study, including investigation of therapeutic efficacy in vivo, is warranted.     

The effects of laser irradiation on osteoblast and osteosarcoma cell proliferation and differentiation in vitro

OBJECTIVE: The aim of this study was to investigate the effects of 670-nm, 780-nm, and 830-nm laser irradiation on cell proliferation of normal primary osteoblast (MC3T3) and malignant osteosarcoma (MG63) cell lines in vitro. BACKGROUND: Some studies have shown that laser phototherapy is able to stimulate the osteogenesis of bone tissue, increasing osteoblast proliferation and accelerating fracture consolidation. It has been suggested that laser light may have a biostimulatory effect on tumor cells. However, the mechanism by which the laser acts on cells is not fully understood. MATERIALS AND METHODS: Neonatal, murine, calvarial, osteoblastic, and human osteosarcoma cell lines were studied. A single laser irradiation was performed at three different wavelengths, at the energies of 0.5, 1, 5, and 10 J/cm(2). Twenty-four hours after laser irradiation, cell proliferation and alkaline phosphatase assays were assessed. RESULTS: Osteoblast proliferation increased significantly after 830-nm laser irradiation (at 10 J/cm(2)) but decreased after 780-nm laser irradiation (at 1, 5, and 10 J/cm(2)). Osteosarcoma cell proliferation increased significantly after 670-nm (at 5 J/cm(2)) and 780-nm laser irradiation (at 1, 5, and 10 J/cm(2)), but not after 830-nm laser irradiation. Alkaline phosphatase (ALP) activity in the osteoblast line was increased after 830-nm laser irradiation at 10 J/cm(2), whereas ALP activity in the osteosarcoma line was not altered, regardless of laser wavelength or intensity. CONCLUSION: Based on the conditions of this study, we conclude that each cell line responds differently to specific wavelength and dose combinations. Further investigations are required to investigate the physiological mechanisms responsible for the contrasting outcomes obtained when using laser irradiation on cultured normal and malignant bone cells.     

Antimicrobial photodynamic therapy combined with conventional endodontic treatment to eliminate root canal biofilm infection

BACKGROUND AND OBJECTIVE: To compare the effectiveness of antimicrobial photodynamic therapy (PDT), standard endodontic treatment and the combined treatment to eliminate bacterial biofilms present in infected root canals. STUDY DESIGN/MATERIALS AND METHODS: Ten single-rooted freshly extracted human teeth were inoculated with stable bioluminescent Gram-negative bacteria, Proteus mirabilis and Pseudomonas aeruginosa to form 3-day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify bacterial burdens. PDT employed a conjugate between polyethylenimine and chlorin(e6) as the photosensitizer (PS) and 660-nm diode laser light delivered into the root canal via a 200-micro fiber, and this was compared and combined with standard endodontic treatment using mechanical debridement and antiseptic irrigation. RESULTS: Endodontic therapy alone reduced bacterial bioluminescence by 90% while PDT alone reduced bioluminescence by 95%. The combination reduced bioluminescence by >98%, and importantly the bacterial regrowth observed 24 hours after treatment was much less for the combination (P<0.0005) than for either single treatment. CONCLUSIONS: Bioluminescence imaging is an efficient way to monitor endodontic therapy. Antimicrobial PDT may have a role to play in optimized endodontic therapy.     

Scanning laser system for photodynamic therapy of choroidal neovascularization

BACKGROUND AND OBJECTIVES: In order to improve selectivity of photodynamic therapy (PDT) to choroidal neovascularization (CNV) associated with age-related macular degeneration, a laser scanning technique was applied to perform focal laser irradiation to the retina, and the occlusion effects of a new device to the choriocapillaris were evaluated in primate eyes. STUDY DESIGN/MATERIALS AND METHODS: The device contains lasers for fundus observation of 785 nm and for PDT of 670 nm, matching the absorption peak of a photosensitizer, ATX-S10(Na). The laser irradiated the shape on the retina specified before treatment and shut off automatically when the predetermined treatment was achieved. The occlusion of the choriocapillaris after PDT was documented by fluorescein and indocyanine green angiography and histology. RESULTS: The area designated for PDT was easily drawn on the touch-screen monitor, and occlusion of the choriocapillaris was achieved precisely in the area pre-selected for treatment with 5 J/cm(2) or more of radiance following administration of 8 mg/kg ATX-S10(Na). CONCLUSIONS: This device is useful for irradiating CNV of any shape, sparing the surrounding retina. Since our previous studies suggested that selective occlusion of CNV would decrease not only the functional disturbance caused by PDT, but also the recurrence of CNV, the present device may allow more effective PDT than the slit-lamp system presently used.     

Comparative study of the phototoxicity of two chrolin type photosensitizers, ATX-S10(Na) and verteporfin, on vascular endothelial and retinal pigment epithelial cells

BACKGROUND AND OBJECTIVES: To compare the phototoxicity in photodynamic therapy (PDT) of ATX-S10(Na) and Verteporfin on human microvascular endothelial cells (HMVEC), vascular endothelial cells of monkey choroid and retina (CRVEC), and human retinal pigment epithelial cells (HRPE). STUDY DESIGN/MATERIALS AND METHODS: PDT was performed in two different ways. In short dye-exposure PDT, HMVEC and CRVEC were exposed to each photosensitizer for 5 minutes followed by laser irradiation of 670 nm wavelength for ATX-S10(Na) or 689 nm for Verteporfin without washing out the photosensitizer in the medium. In long dye-exposure PDT, the cells were exposed to photosensitizers for times ranging from 5 minutes to 2 hours, washed out the photosensitizers, followed by laser irradiation in a fresh medium. PDT was performed on HRPE with PDT doses that resulted in damaging 90% of the HMVEC (ED(90)). Phototoxicity was determined by MTS Assay 1 day after PDT. RESULTS: The degree of phototoxicity depended on the dye concentration, laser dose, and dye exposure time. In short dye-exposure PDT on HMVEC with a laser dose of 50 J/cm(2), the ED(90) was 6.3 microg/ml of ATX-S10(Na) and 0.04 microg/ml of Verteporfin, while in long dye-exposure PDT the ED(90) was 50.0 microg/ml of ATX-S10(Na) and 0.04 microg/ml of Verteporfin when the medium was supplemented with 5% fetal calf serum. The phototoxic rate on HMVEC was higher when the medium contained 5% as contrasted with 10% of serum. In short dye-exposure PDT, the ED(90) of CRVEC was 100 microg/ml of ATX-S10(Na) and an irradiance of 100 J/cm(2), and 0.08 microg/ml of Verteporfin and an irradiance of 100 J/cm(2) when the medium was supplemented with 10% serum. With some doses of short dye-exposure PDT, the ATX-S10(Na) achieved higher phototoxic rates on HMVEC and CRVEC than on the HRPE. However, long dye-exposure PDT with ATX-S10(Na) and short and long dye-exposure PDT with Vereteporfin failed to obtain higher phototoxic rates on HMVEC and CRVEC than on HRPE. CONCLUSIONS: Verteporfin had a higher phototoxicity than ATX-S10(Na) on HMVEC and CRVEC. The CRVEC resisted more than HMVEC following PDT with both photosensitizers. In short dye-exposure PDT, ATX-S10(Na) had a more selective phototoxicity on HMVEC and CRVEC than on HRPE.     

光动力疗法治疗恶性肿瘤作用机制的研究进展

【摘要】 光动力疗法(PDT)是继手术、放化疗等传统治疗肿瘤手段外的一种新的抗肿瘤模式。PDT机制目前尚不完全清楚, 已知其利用肿瘤细胞高摄取光敏剂的特性, 使用相应波长的激光照射, 使光敏剂产生单线态氧或其他活性氧, 通过非细胞凋亡途径或直接高效诱导凋亡或导致肿瘤组织坏死杀死癌细胞。PDT也可损伤肿瘤组织的血管内皮细胞及介导自身免疫系统的激活。     

Endovascular photodynamic therapy using mono-L-aspartyl-chlorin e6 to inhibit Intimal hyperplasia in balloon-injured rabbit arteries

BACKGROUND AND OBJECTIVE: Intimal hyperplasia (IH) leading to restenosis is a major complication of arterial revascularization. The purpose of this study was to investigate the effect of photodynamic therapy (PDT) using mono-L-aspartyl chlorin e6 (NPe6) as a photosensitizer and intraluminal radial irradiation for inhibition of IH experimentally. STUDY DESIGN/MATERIALS AND METHODS: Study of laser transmission through the blood indicated that exclusion of blood is a prerequisite for intraluminal PDT. For homogeneous radial laser irradiation to the vessel wall, we used a newly developed cylindrical diffusing balloon laser fiber. Injuries were induced by pulling a balloon catheter through the right iliac artery of rabbits. One and 6 hours after the NPe6 injection (5mg/kg i.v.), drug distribution was examined by fluorescence microscopy. Nineteen rabbits received NPe6 at the time of injuries and PDT was performed with 664-nm laser at 30 and 10 J/cm(2) (20, 30, 40 mW/cm(2)) 1 hour after the injuries. The arteries were harvested at 2 days. In a second group of rabbits, PDT was given at 30 mW/cm(2) (30 J/cm(2)). Two weeks after treatment, the arteries were removed and examined histologically. RESULTS: NPe6 was found to be distributed selectively in the injured media. Endovascular NPe6-PDT showed complete depletion of smooth muscle cells even with 10 J/cm(2) at 2 days. IH was significantly inhibited at 14 days after PDT. CONCLUSIONS: Endovascular PDT of injured artery using NPe6 can prevent IH in this model of arterial wall injury and may become clinically useful for the prophylaxis of IH.     

Ultraviolet-C-induced apoptosis protected by 635-nm laser irradiation in human gingival fibroblasts

OBJECTIVE: The purpose of this study was to examine the protection afforded by 635-nm irradiation against ultraviolet (UV)-C-induced apoptosis in primary human gingival fibroblasts (hGFs). BACKGROUND DATA: UV irradiation is known to cause photoaging and cellular apoptosis of skin cells and is considered to be one of the leading causes of skin carcinogenesis. MATERIALS AND METHODS: To induce apoptosis, UV-C (100 mJ/cm2) was used to irradiate hGFs. To protect them from apoptosis, pretreatment with 635-nm irradiation was performed for 1 h immediately after cell plating 36 or 48 h before UV-C irradiation. The light source used for irradiation was a continuous-wave 635-nm LED laser emitting at 1 mW/cm2. Experimental samples were selected 24 h after UV-C irradiation. To measure the numbers of apoptotic cells, MTT assay and flow cytometric analyses were performed. For histomorphologic findings, Diff-Quick staining was carried out. Also, the activities and mRNA expression of caspase-3, caspase-8, and caspase-9 were measured. RESULTS: In the present study, the number of apoptotic cells declined in the cells that were pretreated with 635-nm light irradiation in a time-dependent manner. In addition, the activities and mRNA expression of caspase-3, caspase-8, and caspase-9 were significantly recovered by pretreatment with 635-nm irradiation. CONCLUSION: These results suggest that 635-nm visible light irradiation may be used as a protective tool to prevent UV-C-induced apoptosis.     

Analysis of mitochondria,endoplasmic reticulum and actin filaments after PDT with AlPcS<Subscript>4</Subscript>

Photodynamic therapy (PDT) is a therapeutic modality for the treatment of tumors. This technique uses a visible light to activate a photosensitizer compounds, leading to a photo-oxidation process of biological tissue that can induce apoptosis or necrosis both in vivo and in vitro. However many of the cytotoxic effects remain an open question to be investigated. The cytotoxicity to specific cellular targets of classical photosensitizers used in the PDT in vitro has been analyzed in this work. The photosensitizing effects of Chloroaluminum Phthalocyanine Tetrasulfonate (AlPcS₄) were studied on the mitochondria, cytoskeleton and endoplasmic reticulum of HeLa cells. The cells were irradiated with a diode laser (working at 670 nm; energy density of 4.5 J/cm² and power density of 45 mW/cm²). The spectrofluorimetric analysis of the mitochondria showed changes in membrane potential. Cytoskeleton and endoplasmic reticulum showed basic alterations in distribution after PDT treatment, as an indicator of cellular death process.     

The effect of low level laser irradiation on adult human adipose derived stem cells

This study investigated the effect of low level laser irradiation on primary cultures of adult human adipose derived stem cells (ADSC) using a 635-nm diode laser, at 5 J/cm(2) with a power output of 50.2 mW and a power density of 5.5 mW/cm(2). Cellular morphology did not appear to change after irradiation. Using the trypan blue exclusion test, the cellular viability of irradiated cells increased by 1% at 24 h and 1.6% at 48 h but was not statistically significant. However, the increase of cellular viability as measured by ATP luminescence was statistically significant at 48 h (p < 0.05). Proliferation of irradiated cells, measured by optical density, resulted in statistically significant increases in values compared to nonirradiated cells (p < 0.05) at both time points. Western blot analysis and immunocytochemical labeling indicated an increase in the expression of stem cell marker beta1-integrin after irradiation. These results indicate that 5 J/cm(2) of laser irradiation can positively affect human adipose stem cells by increasing cellular viability, proliferation, and expression of beta1-integrin.     

Studies of a vascular-acting photosensitizer, Pd-bacteriopheophorbide (Tookad), in normal canine prostate and spontaneous canine prostate cancer

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. RESULTS: 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. CONCLUSIONS: Tookad-PDT is very effective in ablating prostatic tissue through its vascular effects.     

Growth inhibition effect of HMME-mediated PDT on hepatocellular carcinoma HepG2 cells

Photodynamic therapy (PDT) is considered a promising new strategy for liver cancer treatment. Three elements of PDT—optical output power, irradiation time, and photosensitizer concentration—play important roles in promoting cell death. This research aimed to characterize the effects of hematoporphyrin monomethyl ether (HMME)-based PDT on hepatocellular carcinoma cells HepG2 and thus elucidate the relationship between cell death and the three elements mentioned earlier. Furthermore, in this study, we present a parameter that represents the cumulative effects of these elements. The accumulation of HMME in HepG2 cells was observed by fluorescence microscopy. The absorption spectrum of HMME was detected using fluorescence spectral analysis. The viability of the treated cells was determined using the MTT assay, and cell apoptosis was evaluated using flow cytometry. We found that the fluorescence intensity was positively correlated with the incubation time for up to 2 h. The cell growth inhibition rate was significantly high and gradually increased with increasing concentrations of HMME or increasing light intensity, which was calculated as optical output power × irradiation time. Further analysis revealed an e-exponential decay of the cell survival rate to the product of the HMME concentration and the light intensity. We defined the product as parameter B (B = optical output power × irradiation time × HMME concentration). Similarly, the rate of cell apoptosis showed roughly e-exponential growth to parameter B. In conclusion, HMME-mediated PDT can significantly kill HepG2 cells, and the killing effect was related to the cumulative effects of the optical output power, the irradiation time, and the HMME concentration. Therefore, the newly defined parameter B, as a comprehensive physical quantity, may be of great significance for the regulation of light and photosensitizer according to patient-specific conditions in clinical practice.     

Human pancreatic carcinoma cells are sensitive to photodynamic therapy in vitro and in vivo.

BACKGROUND: The aim of this study was to assess the efficiency of photodynamic therapy (PDT) on human pancreatic cancer cells in vitro and in an animal model. METHODS: Human pancreatic tumour cell lines were submitted to PDT with pheophorbide a (Ph a), a chlorophyll derivative, in culture and after grafting into athymic mice. Ph a was tested in culture (10-10-10-5 mol/l) with a 5-J/cm2 energy treatment and on tumour-bearing Nude mice (30 mg/kg intraperitoneally) with a 100-J/cm2 PDT session. The effect of PDT was assessed in vitro using proliferative, apoptotic and clonogenic tests and in vivo on tumour growth and on the induction of tumour necrosis. RESULTS: PDT inhibited tumour cell growth in culture by affecting DNA integrity. This tumour cell photodamage started at low concentration (10-7 mol/l) as corroborated by clonogenic and tumour growth tests. A strong necrosis was achieved in vivo with a single PDT session. CONCLUSION: PDT destroyed human pancreatic carcinoma after low photosensitizer supply and weak energy application. It exerted this tumoricidal effect via apoptosis induction with a gentle protocol, and apoptosis and/or necrosis with a stronger protocol.