Enhanced Photodynamic Therapy Efficacy Research Articles

Size-Controlled Synthesis of Porphyrinic Metal-Organic Framework and Functionalization for Targeted Photodynamic Therapy.

The understanding of nanomaterials for targeted cancer therapy is of great importance as physical parameters of nanomaterials have been shown to be strong determinants that can promote cellular responses. However, there have been rare platforms that can vastly tune the core of nanoparticles at a molecular level despite various nanomaterials employed in such studies. Here we show targeted photodynamic therapy (PDT) with Zr(IV)-based porphyrinic metal-organic framework (MOF) nanoparticles. Through a bottom-up approach, the size of MOF nanoparticles was precisely tuned in a broad range with a designed functional motif, built upon selection of building blocks of the MOF. In particular, molecular properties of the porphyrinic linker are maintained in the MOF nanoparticles regardless of their sizes. Therefore, size-dependent cellular uptake and ensuing PDT allowed for screening of the optimal size of MOF nanoparticles for PDT while MOF nanoparticle formulation of the photosensitizer showed better PDT efficacy than that of its small molecule. Additionally, Zr6 clusters in the MOF enabled an active targeting modality through postsynthetic modification, giving even more enhanced PDT efficacy. Together with our finding of size controllability covering a broad range in the nano regime, we envision that MOFs can be a promising nanoplatform by adopting advanced small molecule systems into the tunable framework with room for postsynthetic modification.

Enhanced cellular uptake of protoporphyrine IX/linolenic acid-conjugated spherical nanohybrids for photodynamic therapy

Protoporphyrin IX (PpIX) has wide applications in photodynamic diagnosis and photodynamic therapy (PDT) in many human diseases. However, poor water solubility and cancer cell localization limit its direct application for PDT. We improved the water-solubility and cellular internalization of PpIX to enhance PDT efficacy by developing biocompatible PpIX/linolenic acid-conjugated polyhedral oligomeric silsesquioxane (PPLA) nanohybrids. The resulting PPLA nanohybrids exhibited a quasi-spherical shape with a size of <200nm. 1H NMR analysis confirmed the synthesis of PPLA. The singlet oxygen formation of PPLA nanohybrids on laser irradiation was detected by photoluminescence emission. Fluorescence-activated cell sorting (FACS) analysis displayed higher cellular internalization of PPLA compared with free PpIX. In addition, PPLA nanohybrids exhibited significantly reduced dark-toxicity and a high phototoxicity mostly because of apoptotic cell death against human gastric cancer cells. These results imply that the PPLA nanohybrid system may be applicable in PDT.

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

BackgroundLight 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.ResultsIn 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.DiscussionThe 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.

Simple Peptide‐Tuned Self‐Assembly of Photosensitizers towards Anticancer Photodynamic Therapy

AbstractPeptide‐tuned self‐assembly of functional components offers a strategy towards improved properties and unique functions of materials, but the requirement of many different functions and a lack of understanding of complex structures present a high barrier for applications. Herein, we report a photosensitive drug delivery system for photodynamic therapy (PDT) by a simple dipeptide‐ or amphiphilic amino‐acid‐tuned self‐assembly of photosensitizers (PSs). The assembled nanodrugs exhibit multiple favorable therapeutic features, including tunable size, high loading efficiency, and on‐demand drug release responding to pH, surfactant, and enzyme stimuli, as well as preferable cellular uptake and biodistribution. These features result in greatly enhanced PDT efficacy in vitro and in vivo, leading to almost complete tumor eradication in mice receiving a single drug dose and a single exposure to light.

Simple Peptide-Tuned Self-Assembly of Photosensitizers towards Anticancer Photodynamic Therapy.

Peptide-tuned self-assembly of functional components offers a strategy towards improved properties and unique functions of materials, but the requirement of many different functions and a lack of understanding of complex structures present a high barrier for applications. Herein, we report a photosensitive drug delivery system for photodynamic therapy (PDT) by a simple dipeptide- or amphiphilic amino-acid-tuned self-assembly of photosensitizers (PSs). The assembled nanodrugs exhibit multiple favorable therapeutic features, including tunable size, high loading efficiency, and on-demand drug release responding to pH, surfactant, and enzyme stimuli, as well as preferable cellular uptake and biodistribution. These features result in greatly enhanced PDT efficacy in vitro and in vivo, leading to almost complete tumor eradication in mice receiving a single drug dose and a single exposure to light.

Enhancing Photodynamic Therapy Efficacy by Using Fluorinated Nanoplatform

Photodynamic therapy (PDT) is a noninvasive therapeutic modality with fast healing process and little or no scarring. The production of reactive oxygen species is highly dependent on oxygen concentration, and thus, the therapeutic efficacy of PDT would be retarded by inefficient oxygen supply in hypoxic tumor cell and the oxygen self-consuming mechanism of PDT. It is well-known that perfluorocarbons are endowed with properties of enhanced oxygen solubility and transfer capacity. Herein, we prepared a series of nanoplatforms of spherical micelles with different ratios of pentafluorophenyl to porphyrin in the core and utilized these micelles as models to examine the influence of content of fluorinated segments on the PDT effect of porphyrins. It was found for the first time, as far as we are aware, that the production efficacy of singlet oxygen increased with the rising in the ratio of pentafluorophenyl to porphyrin. Thus, this work presents a new avenue to improve PDT efficacy by enhancing oxygen solubility and diffusivity of nanoplatforms with the incorporation of perfluorocarbon segments.

Inhibition of hypoxia inducible factor 1 and topoisomerase with acriflavine sensitizes perihilar cholangiocarcinomas to photodynamic therapy.

Background: Photodynamic therapy (PDT) induces tumor cell death by oxidative stress and hypoxia but also survival signaling through activation of hypoxia-inducible factor 1 (HIF-1). Since perihilar cholangiocarcinomas are relatively recalcitrant to PDT, the aims were to (1) determine the expression levels of HIF-1-associated proteins in human perihilar cholangiocarcinomas, (2) investigate the role of HIF-1 in PDT-treated human perihilar cholangiocarcinoma cells, and (3) determine whether HIF-1 inhibition reduces survival signaling and enhances PDT efficacy.Results: Increased expression of VEGF, CD105, CD31/Ki-67, and GLUT-1 was confirmed in human perihilar cholangiocarcinomas. PDT with liposome-delivered zinc phthalocyanine caused HIF-1α stabilization in SK-ChA-1 cells and increased transcription of HIF-1α downstream genes. Acriflavine was taken up by SK-ChA-1 cells and translocated to the nucleus under hypoxic conditions. Importantly, pretreatment of SK-ChA-1 cells with acriflavine enhanced PDT efficacy via inhibition of HIF-1 and topoisomerases I and II.Methods: The expression of VEGF, CD105, CD31/Ki-67, and GLUT-1 was determined by immunohistochemistry in human perihilar cholangiocarcinomas. In addition, the response of human perihilar cholangiocarcinoma (SK-ChA-1) cells to PDT with liposome-delivered zinc phthalocyanine was investigated under both normoxic and hypoxic conditions. Acriflavine, a HIF-1α/HIF-1β dimerization inhibitor and a potential dual topoisomerase I/II inhibitor, was evaluated for its adjuvant effect on PDT efficacy.Conclusions: HIF-1, which is activated in human hilar cholangiocarcinomas, contributes to tumor cell survival following PDT in vitro. Combining PDT with acriflavine pretreatment improves PDT efficacy in cultured cells and therefore warrants further preclinical validation for therapy-recalcitrant perihilar cholangiocarcinomas.

Multifunctional Nano‐Bioprobes Based on Rattle‐Structured Upconverting Luminescent Nanoparticles

AbstractLanthanide‐doped upconversion nanoparticles (UCNPs) have shown great promise in versatile bioapplications. For the first time, organosilica‐shelled β‐NaLuF4:Gd/Yb/Er nanoprobes with a rattle structure have been designed for dual‐modal imaging and photodynamic therapy (PDT). Benefiting from the unique rattle structure and aromatic framework, these nanoprobes are endowed with a high loading capacity and the disaggregation effect of photosensitizers. After loading of β‐carboxyphthalocyanine zinc or rose Bengal into the nanoprobes, we achieved higher energy transfer efficiency from UCNPs to photosensitizers as compared to those with conventional core–shell structure or with pure‐silica shell, which facilitates a large production of singlet oxygen and thus an enhanced PDT efficacy. We demonstrated the use of these nanoprobes in proof‐of‐concept X‐ray computed tomography (CT) and UC imaging, thus revealing the great potential of this multifunctional material as an excellent nanoplatform for cancer theranostics.

Enhanced photodynamic therapy efficacy of methylene blue-loaded calcium phosphate nanoparticles

Although methylene blue (MB) is the most inexpensive photosensitizer with promising applications in the photodynamic therapy (PDT) for its high quantum yield of singlet oxygen generation, the clinical use of MB has been limited by its rapid enzymatic reduction in the biological environment. To enhance PDT efficacy of MB by preventing the enzymatic reduction, we have developed a new mineralization method to produce highly biocompatible MB-loaded calcium phosphate (CaP-MB) nanoparticles in the presence of polymer templates. The resulting CaP-MB nanoparticles exhibited spherical shape with a size of under 50nm. Fourier transform infrared (FT-IR) and zeta-potential analyses confirmed the insertion of MB into the CaP-MB nanoparticles. The encapsulation of MB in CaP nanoparticles could effectively protect MB from the enzymatic reduction. In addition, the CaP-MB nanoparticles exhibited a good biocompatibility in the dark condition and significantly enhanced PDT efficacy due to apoptotic cell death against human breast cancer cells as compared with free MB, implying that CaP-MB nanoparticle system might be potentially applicable in PDT.

Gold Nanoclusters‐Based Nanoprobes for Simultaneous Fluorescence Imaging and Targeted Photodynamic Therapy with Superior Penetration and Retention Behavior in Tumors

Gold nanoclusters (GNCs) attract increasing attention due to their potential applications in sensing, catalysis, optoelectronics, and biomedicine. Herein, the formation of highly fluorescent glutathione (GSH)‐capped GNCs is achieved through the delicate control of the reduction kinetics and thermodynamic selection of the Au(I)–SG complexes. Furthermore, the GNCs‐based nanoprobes are developed by the covalent coupling folic acid (FA) and PEG (polyethylene glycol) on the surface of GNCs directly, followed by trapping photosensitizer (chlorin e6, Ce6) within PEG networks and attaching to the GNCs surface. The fabricated nanoprobes (Ce6@GNCs‐PEG2K‐FA) possess a uniform particle size (hydrodynamic diameter ≈6.1 ± 1.2 nm), without affecting the yield of singlet oxygen of the trapped Ce6. In vitro studies show the enhanced cellular uptake and satisfactory photodynamic therapy (PDT) effectiveness toward MGC‐803 cells when compared with free Ce6. The biodistribution and excretion pathway studies of the nanoprobes in MGC‐803 tumor‐bearing nude mice reveal their superior penetration and retention behavior in tumors, while the preserved features of renal clearance and stealthy to reticulo‐endothelial system are mainly attributed to the small hydrodynamic diameters and the FA‐capped PEGylated ligands. The enhanced PDT efficacy and the nontoxicity to mice provide an exciting new nano‐platform with promising clinical translational potential.

Nanoscale metal-organic framework for highly effective photodynamic therapy of resistant head and neck cancer.

Photodynamic therapy (PDT) is an effective anticancer procedure that relies on tumor localization of a photosensitizer followed by light activation to generate cytotoxic reactive oxygen species (e.g., 1O2). Here we report the rational design of a Hf–porphyrin nanoscale metal–organic framework, DBP–UiO, as an exceptionally effective photosensitizer for PDT of resistant head and neck cancer. DBP–UiO efficiently generates 1O2 owing to site isolation of porphyrin ligands, enhanced intersystem crossing by heavy Hf centers, and facile 1O2 diffusion through porous DBP–UiO nanoplates. Consequently, DBP–UiO displayed greatly enhanced PDT efficacy both in vitro and in vivo, leading to complete tumor eradication in half of the mice receiving a single DBP–UiO dose and a single light exposure. NMOFs thus represent a new class of highly potent PDT agents and hold great promise in treating resistant cancers in the clinic.

Lanthanide-doped upconversion nanoparticles electrostatically coupled with photosensitizers for near-infrared-triggered photodynamic therapy.

Lanthanide-doped upconversion nanoparticles (UCNPs) have recently shown great promise in photodynamic therapy (PDT). Herein, we report a facile strategy to fabricate an efficient NIR-triggered PDT system based on LiYF4:Yb/Er UCNPs coupled with a photosensitizer of a β-carboxyphthalocyanine zinc (ZnPc-COOH) molecule via direct electrostatic interaction. Due to the close proximity between UCNPs and ZnPc-COOH, we achieved a high energy transfer efficiency of 96.3% from UCNPs to ZnPc-COOH, which facilitates a large production of cytotoxic singlet oxygen and thus an enhanced PDT efficacy. Furthermore, we demonstrate the high efficacy of such a NIR-triggered PDT agent for the inhibition of tumor growth both in vitro and in vivo, thereby revealing the great potential of the UCNP-based PDT systems as noninvasive NIR-triggered PDT agents for deep cancer therapy.

In Vivo Targeted Deep-Tissue Photodynamic Therapy Based on Near-Infrared Light Triggered Upconversion Nanoconstruct

Two major challenges of current photodynamic therapy (PDT) are the limited tissue penetration of excitation light and poor tumor-selectivity of the photosensitizer (PS). To address these issues, we developed a multifunctional nanoconstruct consisting of upconversion nanoparticles (UCNPs) that transform near-infrared (NIR) light to visible light and a photosensitizer zinc(II) phthalocyanine (ZnPc). Folate-modified amphiphilic chitosan (FASOC) was coated on the surface of UCNPs to anchor the ZnPc close to the UCNPs, thereby facilitating resonance energy transfer from UCNPs to ZnPc. Confocal microscopy and NIR small animal imaging demonstrated the enhanced tumor-selectivity of the nanoconstructs to cancer cells that overexpressed folate receptor. Reactive oxygen species (ROS) generation in cancer cells under a 1-cm tissue was higher upon excitation of UCNPs with the 980 nm light than that with 660 nm irradiation. In vivo PDT treatments for deep-seated tumors demonstrated that NIR light-triggered PDT based on the nanoconstructs possessed remarkable therapeutic efficacy with tumor inhibition ratio up to 50% compared with conventional visible light-activated PDT with a noticeable reduced tumor inhibition ratio of 18%. These results indicate that the multifunctional nanoconstruct is a promising PDT agent for deep-seated tumor treatment and demonstrate a new paradigm for enhancing PDT efficacy.

Photodynamic therapy-induced angiogenic signaling: consequences and solutions to improve therapeutic response.

Photodynamic therapy (PDT) can be a highly effective treatment for diseases ranging from actinic keratosis to cancer. While use of this therapy shows great promise in preclinical and clinical studies, understanding the molecular consequences of PDT is critical to designing better treatment protocols. A number of publications have documented alteration in angiogenic factors and growth factor receptors following PDT, which could abrogate treatment effect by inducing angiogenesis and re-establishment of the tumor vasculature. In response to these findings, work over the past decade has examined the efficacy of combining PDT with molecular targeting drugs, such as anti-angiogenic compounds, in an effort to combat these PDT-induced molecular changes. These combinatorial approaches increase rates of apoptosis, impair pro-tumorigenic signaling, and enhance tumor response. This report will examine the current understanding of PDT-induced angiogenic signaling and address molecular-based approaches to abrogate this signaling or its consequences thereby enhancing PDT efficacy.

Radiant near infrared light emitting Diode exposure as skin preparation to enhance photodynamic therapy inflammatory type acne treatment outcome

An alternative approach in the treatment of acne vulgaris is photodynamic therapy (PDT) that uses light and aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) production to eradicate Propionibacterium acnes found in acne lesions. PpIX formation is dependent on ALA percutaneaous penetration. In this study, to enhance ALA penetration and subsequent accumulation of PpIX, skin temperature was increased with radiant infrared (IR) prior to ALA-PDT application and compared to ALA-PDT alone in the treatment of inflammatory acne. Ten patients exhibiting inflammatory acne with a lesion count of > or =10 were assigned to a split face or split back group. One side was pre-treated for 15 minutes with radiant IR light emitting diode (LED) (970 nm), while the other side was used as control. ALA was then applied after which PDT LED (630 nm) was performed on the entire face or back surface. Blinded lesion counts and clinical global assessment of severity were performed based on digital photographs before and 4 weeks after the PDT procedure. This randomized, controlled, and rater-blinded trial revealed a significant difference in median reduction of inflammatory lesions on the IR pre-treated (73%, 95% confidence interval (CI) 51-81%) versus the control side (38%, 95% CI 8-55%) 1 month after PDT (P<0.0001). Clinical assessment of severity was also significantly lower on the IR-treated side than on the control side (median 1, 95% CI 0.74-1.34 vs. 2, 95% CI 1.17-1.72). No unusual treatment-related adverse effects were observed. The reported therapeutic effects may be due to enhanced induction of alterations in transcutaneous diffusion kinetics of the photosensitizer at higher skin temperature and/or conversion of ALA to PpIX. Pre-PDT radiant IR LED exposure appears to be a promising method to enhance PDT efficacy for the treatment of acne lesions.

Nanotechology-Based Strategies to Enhance the Efficacy of Photodynamic Therapy for Cancers

Photodynamic therapy (PDT) combines photosensitizer, visible light and oxygen, which has the characteristics of high selectivity, minimal invasiveness, low side effect, and allowing repetitive application. The photophysics and mechanisms leading to cell death mediated by PDT have been studied extensively, and PDT has been approved as the modality for superficial tumors and non-cancerous diseases worldwide. For non-dermatogoical applications, the photosensitizers are delivered systemically. Selective therapeutic effect against tumor tissues can be provided by the nature of drugs and tumor physiology. Improved targeting photosensitizer helps preventing damage to the surrounding healthy tissue and lowering dose of drugs and light. The use of nanotechnology in photosensitizer delivery is an attractive approach because nanomaterials may satisfy the need for enhancing PDT efficacy. Recent advances in the use of nanotechnology for PDT application include formulation of biodegradable and non-degradable nanoparticles as passive carriers for photosensitizing agents as well as synthesizing photosensitizer-specific target moiety conjugates for active targeting. This article focuses on passive and active targeting strategies involving nanotechnology to enhance PDT efficacy for cancers.

Surfactant−Polymer Nanoparticles Enhance the Effectiveness of Anticancer Photodynamic Therapy

Photodynamic therapy (PDT) is a promising treatment modality for cancer. PDT is based on the concept that photosensitizers, when exposed to light of specific wavelength, generate cytotoxic reactive oxygen species (ROS) capable of killing tumor cells. The effectiveness of PDT has been limited in part by the lack of photosensitizers that accumulate sufficiently in tumor cells and poor yield of ROS from existing photosensitizers. In this report, we investigated whether aerosol OT-alginate nanoparticles can be used as a carrier to enhance the therapeutic efficacy of a model photosensitizer, methylene blue. Methylene blue loaded nanoparticles were evaluated for PDT effectiveness in two cancer cell lines, MCF-7 and 4T1. Encapsulation of methylene blue in nanoparticles significantly enhanced intracellular ROS production, and the overall cytotoxicity following PDT. It also resulted in higher incidence of necrosis. Greater effectiveness of nanoparticles could be correlated with higher yield of ROS with nanoparticle-encapsulated methylene blue. Further, treatment of tumor cells with nanoparticle-encapsulated methylene blue resulted in significant nuclear localization of methylene blue while free drug treatment resulted in its accumulation mainly in the endolysosomal vesicles. In conclusion, encapsulation of methylene blue in aerosol OT-alginate nanoparticles enhanced its anticancer photodynamic efficacy in vitro. Increased ROS production and favorable alteration in the subcellular distribution contribute to the enhanced PDT efficacy of nanoparticle-encapsulated photosensitizer.

The Tyrosine Kinase Inhibitor Imatinib Mesylate Enhances the Efficacy of Photodynamic Therapy by Inhibiting ABCG2

The ATP-binding cassette protein ABCG2 (breast cancer resistance protein) effluxes some of the photosensitizers used in photodynamic therapy (PDT) and, thus, may confer resistance to this treatment modality. Tyrosine kinase inhibitors (TKI) can block the function of ABCG2. Therefore, we tested the effects of the TKI imatinib mesylate (Gleevec) on photosensitizer accumulation and in vitro and in vivo PDT efficacy. Energy-dependent photosensitizer efflux and imatinib mesylate's effects on intracellular accumulation of clinically used second- and first-generation photosensitizers were studied by flow cytometry in murine and human cells with and without ABCG2 expression. Effects of ABCG2 inhibition on PDT were examined in vitro using cell viability assays and in vivo measuring photosensitizer accumulation and time to regrowth in a RIF-1 tumor model. Energy-dependent efflux of 2-(1-hexyloxethyl)-2-devinyl pyropheophorbide-a (HPPH, Photochlor), endogenous protoporphyrin IX (PpIX) synthesized from 5-aminolevulenic acid, and the benzoporphyrin derivative monoacid ring A (BPD-MA, Verteporfin) was shown in ABCG2+ cell lines, but the first-generation multimeric photosensitizer porfimer sodium (Photofrin) and a novel derivative of HPPH conjugated to galactose were minimally transported. Imatinib mesylate increased accumulation of HPPH, PpIX, and BPD-MA from 1.3- to 6-fold in ABCG2+ cells, but not in ABCG2- cells, and enhanced PDT efficacy both in vitro and in vivo. Second-generation clinical photosensitizers are transported out of cells by ABCG2, and this effect can be abrogated by coadministration of imatinib mesylate. By increasing intracellular photosensitizer levels in ABCG2+ tumors, imatinib mesylate or other ABCG2 transport inhibitors may enhance efficacy and selectivity of clinical PDT.

DH‐I‐180‐3‐Mediated Photodynamic Therapy: Biodistribution and Tumor Vascular Damage

An important goal of photodynamic therapy (PDT) for treatment of various cancers is to shorten PDT-performing time and simultaneously enhance PDT efficacy. Here, we investigated the nontumor tissue distribution of and the tumor vascular damage caused by a new photosensitizer, DH-I-180-3, in mice with implanted EMT6 mammary tumor cells. In addition, we performed cell-based assays to evaluate the basic antitumor effect of DH-I-180-3/PDT in EMT6 cells. After administration of PDT, the type of cell death was characterized to be apoptosis, and a change in the mitochondrial membrane potential was also observed within minutes. On the other hand, tumor growth was remarkably retarded in vivo in mice that received DH-I-180-3/PDT, compared with mice in the control group, which were exposed to light irradiation alone. Finally, tumors in some mice nearly healed. The antitumor drug reached a maximum concentration approximately 3 h after administration. However, PDT was most effective when there was substantial accumulation of DH-I-180-3 in the tumor vasculature and in healthy tissue. The histological demonstration provided further evidence of tumor vascular damage. On the basis of these findings, we suggest that PDT with the photosensitizer DH-I-180-3 induces vascular damage with blood vessel shutdown, in addition to direct killing of tumor cells, in mice.