Sasidharan Swarnalatha Lucky

Nanoparticles in Photodynamic Therapy

Sasidharan Swarnalatha Lucky,†,§ Khee Chee Soo,‡ and Yong Zhang*,†,§,∥ †NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, Singapore, Singapore 117456 ‡Division of Medical Sciences, National Cancer Centre Singapore, Singapore, Singapore 169610 Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore 117576 College of Chemistry and Life Sciences, Zhejiang Normal University, Zhejiang, P. R. China 321004

Titania Coated Upconversion Nanoparticles for Near-Infrared Light Triggered Photodynamic Therapy

Because of the limited penetration depth of visible light that generally excites most of the available photosensitizers (PSs), conventional photodynamic therapy (PDT) is limited to the treatment of superficial and flat lesions. Recently, the application of deep penetrating near-infrared (NIR) light excitable upconversion nanoparticles (UCNs) in conjunction with PDT has shown to have clear potential in the treatment of solid tumors due to its ability to penetrate thick tissue. However, various constructs developed so far have certain limitations such as poor or unstable PS loading, reducing their therapeutic efficacy and limiting their application to solution or cell-based studies. In this work, we present a method to fabricate uniform core-shell structured nanoconstruct with a thin layer of photocatalyst or PS-titanium dioxide (TiO2) stably coated on individual UCN core. Our design allows controllable and highly reproducible PS loading, preventing any leakage of PS compared to previously developed nanoconstructs, thus ensuring repeatable PDT results. Further surface modification of the developed nanoconstructs with polyethylene glycol (PEG) rendered them biocompatible, demonstrating good therapeutic efficacy both in vitro and in vivo.

Quantum Dot Capped Magnetite Nanorings as High Performance Nanoprobe for Multiphoton Fluorescence and Magnetic Resonance Imaging

In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications.

Targeted Therapy of Cancer Using Photodynamic Therapy in Combination with Multi-faceted Anti-Tumor Modalities

Photodynamic therapy (PDT) has emerged as one of the important therapeutic options in the management of cancer and other diseases. PDT involves a tumor-localized photosensitizer (PS), which when appropriately illuminated by visible light converts oxygen into cytotoxic reactive oxygen species (ROS), that attack key structural entities within the targeted cells, ultimately resulting in necrosis or apoptosis. Though PDT is a selective modality, it can be further enhanced by combining other targeted therapeutic strategies that include the use of synthetic peptides and nanoparticles for selective delivery of photosensitizers. Another potentially promising strategy is the application of targeted therapeutics that exploit a myriad of critical pathways involved in tumorigenesis and metastasis. Vascular disrupting agents that eradicate tumor vasculature during PDT and anti-angiogenic agents that targets specific molecular pathways and prevent the formation of new blood vessels are novel therapeutic approaches that have been shown to improve treatment outcome. In addition to the well-documented mechanisms of direct cell killing and damage to the tumor vasculature, PDT can also activate the body’s immune response against tumors. Numerous pre-clinical studies and clinical observations have demonstrated the immuno-stimulatory capability of PDT. Herein, we aim to integrate the most important findings with regard to the combination of PDT and other novel targeted therapy approaches, detailing its potential in cancer photomedicine.

Molecular profiling of angiogenesis in hypericin mediated photodynamic therapy

BackgroundPhotodynamic therapy (PDT) involves the administration of a tumor-localizing photosensitizing drug, which is activated by light of specific wavelength in the presence of molecular oxygen thus generating reactive oxygen species that is toxic to the tumor cells. PDT selectively destroys photosensitized tissue leading to various cellular and molecular responses. The present study was designed to examine the angiogenic responses at short (0.5 h) and long (6 h) drug light interval (DLI) hypericin-PDT (HY-PDT) treatment at 24 h and 30 days post treatment in a human bladder carcinoma xenograft model. As short DLI targets tumor vasculature and longer DLI induces greater cellular damage, we hypothesized a differential effect of these treatments on the expression of angiogenic factors.ResultsImmunohistochemistry (IHC) results showed minimal CD31 stained endothelium at 24 h post short DLI PDT indicating extensive vascular damage. Angiogenic proteins such as vascular endothelial growth factor (VEGF), tumor necrosis growth factor-α (TNF-α), interferon-α (IFN-α) and basic fibroblast growth factor (bFGF) were expressed to a greater extent in cellular targeting long DLI PDT compared to vascular mediated short DLI PDT. Gene expression profiling for angiogenesis pathway demonstrated downregulation of adhesion molecules – cadherin 5, collagen alpha 1 and 3 at 24 h post treatment. Hepatocyte growth factor (HGF) and Ephrin-A3 (EFNA3) were upregulated in all treatment groups suggesting a possible activation of c-Met and Ephrin-Eph signaling pathways.ConclusionIn conclusion, long DLI HY-PDT induces upregulation of angiogenic proteins. Differential expression of genes involved in the angiogenesis pathway was observed in the various groups treated with HY-PDT.

In vivo Biocompatibility, Biodistribution and Therapeutic Efficiency of Titania Coated Upconversion Nanoparticles for Photodynamic Therapy of Solid Oral Cancers.

Despite the advantages of using photodynamic therapy (PDT) for the treatment of head and neck tumors, it can only be used to treat early stage flat lesions due to the limited tissue penetration ability of the visible light. Here, we developed near-infrared (NIR) excitable upconversion nanoparticle (UCN) based PDT agent that can specifically target epithelial growth factor receptor (EGFR) overexpressing oral cancer cells, in a bid to widen the application of PDT against thick and solid advanced or recurrent head and neck cancers. In vivo studies using the synthesized anti-EGFR-PEG-TiO2-UCNs following systemic administration displayed no major sub-acute or long term toxic effects in terms of blood biochemical, hematological or histopathological changes at a concentration of 50 mg/kg. NIR-PDT even in the presence of a 10 mm tissue phantom placed over the xenograft tumor, showed significant delay in tumor growth and improved survival rate compared to conventional chlorin-e6 (Ce6) PDT using 665 nm red light. Our work, one of the longest study till date in terms of safety (120 d), PDT efficacy (35 d) and survival (60 d), demonstrates the usefulness of UCN based PDT technology for targeted treatment of thick and bulky head and neck tumors.

Nano-sensitizers for multi-modality optical diagnostic imaging and therapy of cancer

We report novel bioconjugated nanosensitizers as optical and therapeutic probes for the detection, monitoring and treatment of cancer. These nanosensitisers, consisting of hypericin loaded bioconjugated gold nanoparticles, can act as tumor cell specific therapeutic photosensitizers for photodynamic therapy coupled with additional photothermal effects rendered by plasmonic heating effects of gold nanoparticles. In addition to the therapeutic effects, the nanosensitizer can be developed as optical probes for state-of-the-art multi-modality in-vivo optical imaging technology such as in-vivo 3D confocal fluorescence endomicroscopic imaging, optical coherence tomography (OCT) with improved optical contrast using nano-gold and Surface Enhanced Raman Scattering (SERS) based imaging and bio-sensing. These techniques can be used in tandem or independently as in-vivo optical biopsy techniques to specifically detect and monitor specific cancer cells in-vivo. Such novel nanosensitizer based optical biopsy imaging technique has the potential to provide an alternative to tissue biopsy and will enable clinicians to make real-time diagnosis, determine surgical margins during operative procedures and perform targeted treatment of cancers.

Altered expression of cell adhesion molecules leads to differential uptake of hypericin in urothelial cancer

OBJECTIVE To elucidate the mechanism behind selective uptake of hypericin in bladder cancer after intravesical instillation for photodynamic diagnosis of urothelial cell carcinoma of bladder. PATIENTS AND METHODS Clinical studies were done on a series of 60 bladder cancer biopsies obtained from 28 patients who received intravesical instillations with 8 μM hypericin. Serial 5 μm cryosections were cut from 43 biopsies, and expression of the E-cadherin and associated catenins were determined using immunohistochemical and immunofluorescence staining. Hypericin was assessed using fluorescence confocal laser scanning microscopy. In addition, mRNA expression of these cell-adhesion molecules was analyzed in 17 biopsies using reverse transcription-PCR. RESULTS Increased variability in the expression of E-cadherin and associated molecules was found in high-grade, advanced stage bladder carcinoma. An inverse association was found between immunoreactivity for E-cadherin, β- and γ-catenin, and both stage and grade of cancer (P < 0.05). A positive association was observed between the hypericin fluorescence and tumor grade. There was a significant down-regulation of E-cadherin and β-catenin mRNA in grade 2 and 3 tumors. Although a small sample size was studied, it provided sufficient proof to support the hypothesis that altered expression of cell adhesion molecules would lead to preferential hypericin uptake in urothelial cell carcinoma. CONCLUSIONS Our study has unraveled one of the many factors contributing to the selective uptake of hypericin in bladder cancer. We have thus identified the effects of alteration of E-cadherin-catenin complex and transformed intercellular junction in the modified paracellular uptake of hypericin that provides the rationale for using this photosensitizer in photodynamic diagnosis of bladder carcinoma.