Photodynamic modification of disulfonated aluminium phthalocyanine fluorescence in a macrophage cell line.

Disulfonated aluminium phthalocyanine (AlS(2)Pc) is used experimentally as a photosensitiser for both photodynamic therapy (PDT) and photochemical internalisation (PCI). In this study we have focused on modifications in intracellular photosensitiser localisation and fluorescence intensity in macrophages during and after photoirradiation. Since macrophages are highly abundant in tumour tissue and readily accumulate AlS(2)Pc both in vivo and in vitro, we investigated PDT-induced changes of AlS(2)Pc fluorescence in the murine macrophage cell line J774A.1 using CCD fluorescence imaging microscopy. The distinct intracellular localization disappeared upon red laser irradiation and was replaced by a uniform distribution accompanied by a transient fluorescence intensity increase using higher AlS(2)Pc concentrations, followed by photobleaching after further irradiation. A short period of irradiation was sufficient to induce the intracellular redistribution and intensity increase, which then continued in the dark without further laser irradiation. However in the absence of oxygen no fluorescence intensity increase or redistribution was observed. This finding favours the general assumption of photodynamic destruction of organelle membranes resulting in the observed redistribution of the phthalocyanine. No other long-lived fluorescent photoproducts were observed during irradiation. Under deoxygenated conditions slower photobleaching was observed, and photobleaching quantum yields were estimated under aerated and deoxygenated conditions. The participation of reactive oxygen intermediates (ROS) generated during irradiation was indicated by intracellular oxidation of 2',7'-dichlorodihydrofluorescein to the fluorescent 2',7'-dichlorofluorescein in macrophages. The oxygen dependence of these photomodification processes is relevant to the application of AlS(2)Pc to photochemical internalisation which relies on photosensitiser redistribution in cells upon light exposure.     

Light Fractionation Significantly Increases the Efficacy of Photodynamic Therapy Using BF-200 ALA in Normal Mouse Skin

Background

Light fractionation significantly increases the efficacy of 5-aminolevulinic acid (ALA) based photodynamic therapy (PDT) using the nano-emulsion based gel formulation BF-200. PDT using BF-200 ALA has recently been clinically approved and is under investigation in several phase III trials for the treatment of actinic keratosis. This study is the first to compare BF-200 ALA with ALA in preclinical models.

Results

In hairless mouse skin there is no difference in the temporal and spatial distribution of protoporphyrin IX determined by superficial imaging and fluorescence microscopy in frozen sections. In the skin-fold chamber model, BF-200 ALA leads to more PpIX fluorescence at depth in the skin compared to ALA suggesting an enhanced penetration of BF-200 ALA. Light fractionated PDT after BF-200 ALA application results in significantly more visual skin damage following PDT compared to a single illumination. Both ALA formulations show the same visual skin damage, rate of photobleaching and change in vascular volume immediately after PDT. Fluorescence immunohistochemical imaging shows loss of VE-cadherin in the vasculature at day 1 post PDT which is greater after BF-200 ALA compared to ALA and more profound after light fractionation compared to a single illumination.

Discussion

The present study illustrates the clinical potential of light fractionated PDT using BF-200 ALA for enhancing PDT efficacy in (pre-) malignant skin conditions such as basal cell carcinoma and vulval intraepithelial neoplasia and its application in other lesion such as cervical intraepithelial neoplasia and oral squamous cell carcinoma where current approaches have limited efficacy.     

Light fractionation does not enhance the efficacy of methyl 5-aminolevulinate mediated photodynamic therapy in normal mouse skin.

Previous work demonstrated that fractionated illumination using two fractions separated by a dark interval of 2 h, significantly enhanced the clinical efficacy of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA). Considering the increasing clinical use of methyl 5-aminolevulinate (MAL) and the expected gain in efficacy by light fractionation we have investigated the response to MAL-PDT using a single and a two-fold illumination scheme and compared that with ALA-PDT. Our results show that fractionated illumination does not enhance the efficacy of PDT using MAL as it does using ALA despite the comparable fluorescence intensities at the end of the first light fraction and at the start of the second light fraction. Only the initial rate of photobleaching was slightly greater during ALA-PDT although the difference was small. Previously we hypothesized that cells surviving the first fraction are more susceptible to the second fraction. Since this is not true for MAL-PDT our data suggest that the distribution of MAL and ALA in tissues, and therefore the site of PDT induced damage, is an important parameter in the mechanism underlying the 2-fold illumination scheme.     

光学成像技术在体研究肿瘤的光动力效应

光动力疗法 (PDT) 已发展成为一种较成熟的肿瘤治疗方法, PDT 诱导的血管损伤是杀死肿瘤的重要机制之一 . 为了在活体肿瘤模型上实时监测 PDT 导致的血管损伤效应,使用稳定高表达绿色荧光蛋白 (GFP) 的人涎腺腺样囊性癌细胞株 (ACC-M-GFP) ,建立了基于鸡胚尿囊膜 (CAM) 的肿瘤模型 . 应用荧光成像技术对肿瘤的生长位置、大小,以及治疗区域进行方便精确的定位;利用激光散斑成像技术,实时监测 CAM 上肿瘤周围血管的血液动力学参数 . 发现不同光动力剂量所导致的血管损伤有显著不同 . 结果表明,荧光标记的鸡胚尿囊膜肿瘤模型为研究 PDT 导致的血管损伤效应提供了良好的实验模型,激光散斑成像技术适用于实时监测 PDT 过程中血管结构、血流速度的变化,由此得出血液灌注率可用以评估 PDT 对肿瘤周围血管的损伤效应 .     

Role of mitochondria in cell death induced by Photofrin-PDT and ursodeoxycholic acid by means of SLIM.

The present study was undertaken to find new ways to improve efficacy of photodynamic therapy (PDT). We investigated the combinatory effect of the photosensitizer Photofrin and ursodeoxycholic acid (UDCA). UDCA is a relatively non-toxic bile acid which is used inter alia as a treatment for cholestatic disorders and was reported to enhance PDT efficiency of two other photosensitizers. Since besides necrosis and autophagic processes apoptosis has been found to be a prominent form of cell death in response to PDT for many cells in culture, several appropriate tests, such as cytochrome c release, caspase activation and DNA fragmentation were performed. Furthermore spectral resolved fluorescence lifetime imaging (SLIM) was used to analyse the cellular composition of Photofrin and the status of the enzymes of the respiratory chain. Our experiments with two human hepatoblastoma cell lines revealed that the combination of Photofrin with UDCA significantly enhanced efficacy of PDT for both cell lines even though the underlying molecular mechanism for the mode of action of Photofrin seems to be different to some extent. In HepG2 cells cell death was clearly the consequence of mitochondrial disturbance as shown by cytochrome c release and DNA fragmentation, whereas in Huh7 cells these features were not observed. Other mechanisms seem to be more important in this case. One reason for the enhanced PDT effect when UDCA is also applied could be that UDCA destabilizes the mitochondrial membrane. This could be concluded from the fluorescence lifetime of the respiratory chain enzymes which turned out to be longer in the presence of UDCA in HepG2 cells, suggesting a perturbation of the mitochondrial membrane. The threshold at which PDT damages the mitochondrial membrane was therefore lower and correlated with the enhanced cytochrome c release observed post PDT. Thus enforced photodamage leads to a higher loss of cell viability.     

Photobleaching kinetics, photoproduct formation, and dose estimation during ALA induced PpIX PDT of MLL cells under well oxygenated and hypoxic conditions.

Fluorescence photobleaching and photoproduct formation were investigated during delta-aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) PDT of MLL cells in vitro. Cells were incubated in either 0.1 or 1.0 mM ALA for 4 h and were treated with 532 nm or 635 nm light under well oxygenated or hypoxic conditions. Fluorescence spectra were acquired during treatment. Photobleaching and photoproduct formation were quantified using singular value decomposition fitting of fluorescence spectra to experimentally determined basis spectra for PpIX, photoprotoporphyrin (Ppp), product II (peak at 655 nm), and product III (peak at 618 nm). PpIX photobleaching occurred under both normal and hypoxic conditions. The photobleaching kinetics could not be explained by purely first- or second-order photobleaching kinetics, and were attributed to differences in PpIX binding at the two ALA incubation concentrations. Ppp was the main photoproduct and accumulated in higher levels in the absence of oxygen, likely a result of reduced Ppp photobleaching under hypoxia. Increases in product II fluorescence occurred mainly in the presence of oxygen. To assess potential fluorescence based PDT dose metrics, cell viability was measured at select times during treatment using a colony formation assay. Cell survival correlated well to changes in product II fluorescence, independent of oxygenation, sensitizer concentration, and treatment wavelength, suggesting that this product is primarily a result of singlet oxygen mediated reactions and may potentially be useful to quantify singlet oxygen dose during PDT.     

藻蓝蛋白亚基脂质体光动力学抗乳腺癌细胞的实验研究

目的:研究PEG修饰的藻蓝蛋白亚基光敏剂长循环脂质体介导的光动力疗法抗乳腺癌的效果.方法:采用薄膜水合-超声分散法制备PEG修饰的藻蓝蛋白亚基脂质体(PEG-PCS-lip),MTT法检测藻蓝蛋白亚基脂质体对MCF-7(人乳腺癌细胞)、MA-782(鼠乳腺癌细胞)的光动力杀伤效果,流式细胞术(FCM)分析其对肿瘤细胞周期的影响,并对乳腺癌模型鼠做PDT治疗.结果:PEG-PCS-lip介导的PDT作用对乳腺癌细胞有良好的光动力疗效,对MCF-7及MA-782细胞IC_(50)(半数抑制浓度)分别为68 μg/mL、70 μg/mL;FCM的结果显示,当PEG-PCS-lip 浓度为50 μg/mL时,MCF-7凋亡率约为30.5 %; 用10 mg/kg PEG-PCS-lip静脉注射荷瘤小鼠,光照剂量为208.2 J/cm~2时,其抑瘤率可达到72 %;组织切片观察PDT作用后的肿瘤组织,瘤体中间以细胞凋亡为主,瘤体外周以细胞坏死为主,由血管损伤而形成的空腔增多.结论:PEG-PCS-lip在体外对乳腺癌细胞有良好的光动力杀伤效果,肿瘤细胞凋亡及瘤血管破坏是导致肿瘤细胞死亡的主要原因.     

In vivo multimodal tumor imaging and photodynamic therapy with novel theranostic agents based on the porphyrazine framework-chelated gadolinium (III) cation

BackgroundA promising strategy for cancer diagnosis and therapy is the development of an agent for multimodal imaging and treatment. In the present paper we report on two novel multifunctional agents prepared on the porphyrazine pigment platform using a gadolinium (III) cation chelated by red-fluorescent tetrapyrrole macrocycles (GdPz1 and GdPz2).MethodsSpectral and magnetic properties of the compounds were analyzed. Monitoring of GdPz1 and GdPz2 accumulation in the murine colon carcinoma CT26 was performed in vivo using fluorescence imaging and MRI. The photobleaching of GdPz1 or GdPz2 and tumor growth rate after photodynamic therapy (PDT) were assessed.ResultsGdPz1 and GdPz2 demonstrated the selective accumulation in tumor that was indicated by higher fluorescence intensity in the tumor area in comparison with the normal tissues. The results of MRI in vivo showed that GdPz1 or GdPz2 provided significant contrast enhancement of the tumor in T1 MR images. PDT with GdPz2 resulted in ~ 20% decrease in fluorescence intensity of the compound and the inhibition of tumor growth.ConclusionsWe assessed the efficiency of two innovative Gd(III) cation-porphyrazine chelates as bimodal MR and fluorescent probes and photosensitizers for PDT and showed their potentials for tumor diagnostics and treatment.General significanceWater-soluble structures simple in preparation and administration into the body represent special interest for theranostics of tumors. Novel porphyrazine macrocycles chelating a central gadolinium cation demonstrated a good prospect as effective multimodal agents, representing a new approach to MRI and fluorescence imaging guided PDT.     

Specific fluorescent tracers. Imaging and applications for photodynamic therapy

Our main objective is to enlarge the fluorescence use in biosciences, with especially the photodynamic therapy (PDT) used for cancer treatment as one of the target applications. Meta-tetra(hydroxyphenyl)chlorin (m-THPC) is a second-generation photosensitiser, applied in photodynamic therapy. The localisation of this sensitiser as well as its induced cell death mechanisms in human breast cancer cells (MCF-7 and its resistant subline MCF-7DXR, DXR: doxorubicin) were evaluated using fluorescence microscopy. In addition, we will present two additional routes, whose aims are to create new features to respond to the PDT questioning: firstly, the synthesis of fluorescent tracers, with a particular attention to the presence of hydrophilic groups (glucosamine ring) on the basic fluorophore structure to orientate the localisation of the probe and, secondly, the use of scanning near-field optical microscopy to reach a better resolution for the fluorescence microscopy analysis.     

Dissolving microneedles containing aminolevulinic acid improves protoporphyrin IX distribution

One important limitation of topical photodynamic therapy (PDT) is the limited tissue penetration of precursors. Microneedles (MNs) are minimally invasive devices used to promote intradermal drug delivery. Dissolving MNs contain drug-associated to polymer blends, dissolving after insertion into skin, allowing drug release. This study comprises development and characterization of a pyramidal model of dissolving MNs (500 μm) prepared with 5% wt/wt aminolevulinic acid and 20% wt/wt Gantrez AN-139 in aqueous blend. Protoporphyrin IX formation and distribution were evaluated in tumor mice model by using fluorescence widefield imaging, spectroscopy, and confocal microscopy. MNs demonstrated excellent mechanical resistance penetrating about 250 μm with minor size alteration in vitro, and fluorescence intensity was 5-times higher at 0.5 mm on average compared to cream in vivo (being 10 ± 5 a.u. for MNs and 2.4 ± 0.8 a.u. for cream). Dissolving MNs have overcome topical cream application, being extremely promising especially for thicker skin lesions treatment using PDT.     

Development of a new photosensitizer on the basis of ytterbium porphyrazine complex

The tetraphenyltetracyanoporphyrazine complex of ytterbium has been studied as a potential photosensitizer for fluorescence diagnostics and photodynamic therapy (PDT) of cancer. It has been shown that the new compound has an intensive absorption and fluorescence in the "tissue optical window". In particular, the absorption maximum of the complex is at the wavelength of 590 nm, and the fluorescence emission maximum is at 640 nm. A strong fluorescence enhancement with a 50-fold increase in the quantum yield has been revealed in blood serum. The experiments on human cancer cells line have demonstrated that the complex penetrates the cells in vitro and is located around the nuclei. The biodistribution and pharmacokinetics of the complex in animals have been investigated in vivo by a new method of transillumination fluorescence imaging using a peculiar setup. It has been found that the period of maximum uptake of the complex in mouse cervical carcinoma is from 3 to 6 h after i.v. injection, with the half-life in the tumor being 24 h. However, the selectivity of the complex in the tumor is not high enough. The time of clearance from the body is about 48 h. The area of the strongest fluorescence in the abdominal cavity in in vivo images is anatomically recognized as the intestine. This indicates that the new compounds undergo mainly the hepatic clearance mainly. The conventional methods ex vivo (confocal microscopy and point spectroscopic measurements) have detected the largest content of the complex in the intestine, liver, skin and tumor tissue. In general, the optical characteristics of the ytterbium porphyrazine complex as well as the features of its interaction with biological objects make it promising drug candidate for the photodynamic therapy and/or fluorescence diagnostics of cancer. However, a search for other novel formulations possessing a higher tumor selectivity remains an urgent problem.     

基于量子点CdSe两次给药PDT体外灭活HL60的最佳参数实验研究

光漂白是光动力疗法（Photodynamic therapy,PDT）中的一个伴随过程,其存在会影响光敏剂的光敏性能并消耗光敏剂.初步探讨了基于量子点CdSe的光动力疗法中两次给药的问题、给药最佳时间间隔、二次给药的最佳作用参数及正常的与药物处理过的白血病HL60细胞表面的超微结构变化.实验表明,一次给药在量子点浓度为1.0 μmol/L且18 J/cm2的光剂量作用下,PDT效率达到61.0％;经过48 h后,进行二次给药,在量子点浓度为0.75 μmol/L,18 J/cm2光剂量作用下,PDT效率达到了72.1％,较一次给药有了较大幅度提升;扫描电子显微镜（SEM）观察药物作用前后的白血病HL60细胞表面超微结构,结果显示,细胞表面发生了一些显著的变化,由此推测细胞膜可能是量子点CdSe介导的光动力疗法（CdSe-PDT）灭活白血病HL60细胞的一个重要突破口;最后对量子点CdSe光致毒性的机制进行了初步探讨.     

Antinucleosome antibody-modified liposomes and lipid-core micelles for tumor-targeted delivery of therapeutic and diagnostic agents

Liposomes and lipid-core micelles prepared of polyethylene glycol-phosphatidylethanolamine (PEG-PE) conjugates have been modified with nucleosome-specific monoclonal antinuclear autoantibody (ANA) 2C5 (mAb 2C5) specifically recognizing a broad variety of cancer cells through the cancer cell surface-bound nucleosomes. mAb 2C5 preserves its specific properties upon the binding with the lipid-based pharmaceutical nanocarriers, and 2C5-modified immunoliposomes and immunomicelles demonstrate an enhanced binding with tumor cells both in vitro and in vivo. We have investigated the delivery of therapeutic and diagnostic agents with such tumor-targeted immunoliposomes and immunomicelles to various tumors in vivo and in vitro. Both lipid-based nanocarriers provided enhanced tumor delivery of imaging agents ((111)In) and antitumor drugs (doxorubicin and photodynamic therapy agents) to tumor cells under different experimental settings. Pharmaceutical lipid-based nanoparticular carriers modified with mAb 2C5 could represent universal systems for tumor-specific delivery of various soluble and insoluble pharmaceuticals.     

Relation between intracellular location and photodynamic efficacy of 5-aminolevulinic acid-induced protoporphyrin IX in vitro. Comparison between human glioblastoma cells and other cancer cell lines.

A promising clinical application of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PP IX) is fluorescence detection and photodynamic treatment of residual tumour tissue during surgical resection of high grade malignant glioma. U373 MG human glioblastoma cells were used as a model system to study the relation between intracellular location and photodynamic efficacy of 5-ALA-induced PP IX in more detail. Therefore, ultra-sensitive fluorescence microscopy, using either optical excitation of whole cells or selective excitation of the plasma membrane by an evanescent electromagnetic field, was combined with quantitative measurements of intracellular porphyrin amount and phototoxicity. Glioblastoma cells accumulated PP IX to a moderate extent as compared to T47D breast cancer cells (high accumulation) or OV2774 ovarian cancer cells (low accumulation). Although photodynamic inactivation of the different cell lines (decreasing in the order T47D > U373 MG > OV2774) seemed to be directly related to PP IX accumulation, examination of the data in more detail revealed that photodynamic efficacy per photosensitizer molecule (PE) was about two times higher in glioblastoma and ovarian cancer cells as compared to breast cancer cells. The different photodynamic efficacy of PP IX was related to the different intracellular location. In contrast to breast cancer cells where PP IX fluorescence was localized in small granules, PP IX fluorescence in glioblastoma cells and ovarian cancer cells originated mainly from cellular membranes. Thus, the intracellular location of PP IX in a predominantly lipophilic environment, characterized by a comparably high photostability (probed by photobleaching and photoproduct formation) and a lower degree of porphyrin aggregation (probed previously by fluorescence decay kinetics), seems to be the key factor for high photodynamic efficacy of 5-ALA-induced PP IX. In the case of OV2774 ovarian cancer cells, however, a low PP IX accumulation limited cell inactivation upon irradiation, whereas the results obtained for glioblastoma cells are encouraging to develop PDT to an additional therapeutic option for the treatment of tumour margins in patients who underwent fluorescence-guided resection of high grade malignant glioma after 5-ALA administration.     

Enhancement of the photodynamic antitumor effect by streptococcal preparation OK-432 in the mouse carcinoma

 Biological response modifier antitumor effects are enhanced by the activation of the host defense mechanisms. We have investigated the antitumor effect of photodynamic therapy (PDT) and/or local administration of a biological response modifier, the streptococcal preparation OK-432, on transplanted NR-S1 mouse squamous cell carcinoma. Hematoporphyrin oligomers (20 mg/kg body weight) were used to photosensitize PDT. A pulsed Nd:YAG dye laser, tuned at 630 nm, was used as the light source. The laser power was 15 mJ cm⁻² pulse⁻¹, and the irradiation time was 40 min. The photosensitizer was injected intraperitoneally 48 h before laser irradiation. Where used, OK-432 was injected into the tumor either 3 h prior to PDT or immediately afterwards. The antitumor effects were evaluated 48 h after each protocol by (a) estimating the area of tumor necrosis (%) in hematoxylin/eosin-stained specimens, and (b) bromodeoxyuridine immunohistochemistry. Furthermore, the tumor sizes were evaluated 3, 7 and 10 days after each protocol, and the survival time after each protocol was evaluated as well. The anti-tumor effect of PDT was enhanced by administration of OK-432 3 h before PDT, whereas the administration of OK-432 immediately after PDT did not potentiate a PDT antitumor effect. Treatment with OK-432 alone had little effect on tumors. Photodynamic therapy in combination with local administration of OK-432 3 h before PDT is considered to be a useful treatment modality. Received: 23 July 1999 / Accepted: 31 May 2000     

Photosensitization of aqueous model systems by hypericin.

Absorption and fluorescence measurements of purified hypericin (HY) were made in various media. Photosensitization of two aqueous systems was investigated: resealed red blood cell membranes (ghosts) and hen lysozyme (Lys). Solubilization of HY by ghost membranes was shown by means of diffuse reflectance spectroscopy. Visible light irradiation of the ghosts incorporating HY led to lipid peroxidation with evidence of singlet oxygen involvement. A binding model applicable for insoluble ligands is indicative of strong HY binding to HSA. The HY-HSA complex photosensitized inactivation of Lys. The pseudo-first-order reaction kinetics with protection by azide ion are consistent with a Type II mechanism mediated by singlet oxygen. The results are discussed in the context of the HY photodynamic and antiretroviral activities.     

Polycation liposome enhances the endocytic uptake of photosensitizer into cells in the presence of serum

To construct a novel drug delivery carrier that possesses high therapeutic efficacy with low dosage, we designed polyethylenimine-modified liposome (polycation liposome, PCL) and examined the entrapment of photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA), for antiangiogenic photodynamic therapy (PDT). Photosensitizer entrapped in PCLs showed enhanced phototoxicity for a human vascular endothelial cell line, ECV304, in comparison with that for nonmodified control liposome. Interestingly, phototoxicity of control liposomal BPD-MA was suppressed in the presence of serum, but PCL maintained the phototoxicity in the presence of serum following PCL-mediated PDT treatment due to the stability of PCL and the reduced detachment of encapsulated photosensitizer from liposome to serum. In fact, PCL enhanced the uptake level of BPD-MA to ECV304 cells despite the presence or absence of serum. Since polycation modification enhances bioavailability of the liposomal photosensitizer and this property is maintained in the presence of serum, PCL would be useful for antiangiogenic PDT.     

Photofrin Based Photodynamic Therapy and miR-99a Transfection Inhibited FGFR3 and PI3K/Akt Signaling Mechanisms to Control Growth of Human Glioblastoma In Vitro and In Vivo

Glioblastoma is the most common malignant brain tumor in humans. We explored the molecular mechanisms how the efficacy of photofrin based photodynamic therapy (PDT) was enhanced by miR-99a transfection in human glioblastoma cells. Our results showed almost similar uptake of photofrin after 24 h in different glioblastoma cells, but p53 wild-type cells were more sensitive to radiation and photofrin doses than p53 mutant cells. Photofrin based PDT induced apoptosis, inhibited cell invasion, prevented angiogenic network formation, and promoted DNA fragmentation and laddering in U87MG and U118MG cells harvoring p53 wild-type. Western blotting showed that photofrin based PDT was efficient to block the angiogenesis and cell survival pathways. Further, photofrin based PDT followed by miR-99a transfection dramatically increased miR-99a expression and also increased apoptosis in glioblastoma cell cultures and drastically reduced tumor growth in athymic nude mice, due to down regulation of fibroblast growth factor receptor 3 (FGFR3) and PI3K/Akt signaling mechanisms leading to inhibition of cell proliferation and induction of molecular mechanisms of apoptosis. Therefore, our results indicated that the anti-tumor effects of photofrin based PDT was strongly augmented by miR-99a overexpression and this novel combination therapeutic strategy could be used for controlling growth of human p53 wild-type glioblastomas both in vitro and in vivo.     

A non-aggregated silicon(IV) phthalocyanine-lactose conjugate for photodynamic therapy

To develop a highly efficient photosensitizer for photodynamic therapy (PDT), we have designed and synthesized a phthalocyanine-lactose conjugate (Pc-Lac) through axial modification of silicon(IV) phthalocyanine with lactose moieties. With the lactose substituents, Pc-Lac is highly hydrophilic and non-aggregated with efficient reactive oxygen species (ROS) generation in aqueous media. With these desirable properties, Pc-Lac shows high photocytotoxicity and cellular uptake toward HepG2 cells. In addition, in vivo fluorescence imaging shows that Pc-Lac could selectively remain at tumor site, leading to its enhanced photodynamic efficacy against H22 tumor-bearing mice. Therefore, Pc-Lac shows a great potential as a highly efficient molecular photosensitizer for PDT.     

The potential application of chlorin e6-polyvinylpyrrolidone formulation in photodynamic therapy.

Much research has been focused on developing effective drug delivery systems for the preparation of chlorins as potential photosensitizers for PDT. This report describes the evaluation of a new water-soluble formulation of chlorin e6 consisting of a complex of trisodium salt chlorin e6 and polyvinylpyrrolidone (Ce6-PVP) for application in photodynamic therapy (PDT) with 2 specific aims: (i) to investigate its fluorescence kinetics in skin, normal and tumor tissue after intravenous administration, and (ii) to investigate its PDT efficacy. Our results demonstrate that this new formulation possesses photosensitizing properties with rapid accumulation in tumor tissue observed within 1 h after intravenous administration. Although high selectivity in tumor tissue was found between the period of 3 and 6 h, the efficacy of Ce6-PVP mediated PDT was best at 1 h drug-light interval. It is suggested that, the extent of tumor necrosis post PDT is dependent on the plasma concentration of Ce6-PVP, implying a vascular mediated cell death mechanism. A faster clearance rate of Ce6-PVP from the skin of nude mice was observed compared to Ce6. The new formulation of Ce6-PVP seems to show promise as an effective therapeutic agent.