Molecular Imaging of CD44-Overexpressing Gastric Cancer in Mice Using T2 MR Imaging.

Novel diagnostic techniques have been developed in many research area using targetable contrast agents with magnetic resonance imaging (MRI) for cancer diagnosis. For cancer diagnosis, the use of MRI with biocompatible targeting moieties and manganese ferrite nanoparticles (MFNPs) is preferred. Thus, we synthesized MFNPs using a thermal decomposition method which enables sensitive T2 or T2 Turbo Spin Echo (TSE) MRI and coated them with hyaluronic acid (HA). The high targeting ability of HA-MFNPs was observed at MKN-45 cells (gastric cancer cell line) which high-expressing CD44 in contrast with MKN-28 cells which low-expressing CD44. We also prepared the gastric cancer mice model using MKN-45 cells which has the stem-like property was implanted into BALB/c nude mice. And then HA-MFNPs of the T2 contrast enhancement effects and targeting ability were investigated by in vivo MR imaging. As a result of these studies, we conclude that HA coated MFNPs can be effectively used as a novel probes for visualizing gastric cancer stem cells.

Quantification of doping state of redox sensitive nanoparticles for probing the invasiveness of cancer cells using surface enhanced Raman scattering.

Redox activity is known to regulate migration, invasion, metastasis, proliferation, and vascularization of cancer. Because cancer is heterogeneous, the role of redox activity in different cancers and cancer-related processes vary widely. In this study, water soluble, Tween 80-coated polyaniline (TPAni) nanoparticles were synthesized and used as nano-agents for sensing the redox activities of various cancer cells. To identify the relationship between the redox activity and the aggressiveness of cancer cells, two different cancer cell lines, derived from the same tissue but different with regards to aggressiveness, were selected for study. First, the cancer cell lines were incubated with TPAni nanoparticles, and an absorbance ratio obtained from the cell culture media was used as a colorimetric indicator of the redox activities of the cells. Simultaneously, hydrophobically modified filter papers coated with silver nanosnowflakes (SNSF) were used as sensing substrates for surface enhanced Raman scattering (SERS). SERS spectra obtained from varying concentrations of rhodamine 6G were used to confirm the detection limit of the SNSF-based SERS substrate. Cell culture media containing TPAni nanoparticles were treated with the SNSF-containing SERS substrates to examine the redox activities of the various cancer cell lines.The redox activities of cancer cell lines were confirmed by absorbance spectral analysis, and these redox activities were better identified via an SERS analysis method. A SNSF-containing SERS substrate, fabricated from SNSF and filter paper, was used to sense redox activity in cancer cell lines and to further identify correlations between redox activity and cancer cell line aggressiveness, as indicated by the use of EpCAM as a biomarker. Finally, potential of â€‹in vivo â€‹redox activity sensing was also confirmed.

Near-Infrared Fluorescent Probe Activated by Nitroreductase for In Vitro and In Vivo Hypoxic Tumor Detection.

Tumor hypoxia is correlated with increased resistance to chemotherapy and poor overall prognoses across a number of cancer types. We present here a cancer cell-selective and hypoxia-responsive probe (fol-BODIPY) designed on the basis of density functional theory (DFT)-optimized quantum chemical calculations. The fol-BODIPY probe was found to provide a rapid fluorescence "off-on" response to hypoxia relative to controls, which lack the folate or nitro-benzyl moieties. In vitro confocal microscopy and flow cytometry analyses, as well as in vivo near-infrared optical imaging of CT26 solid tumor-bearing mice, provided support for the contention that fol-BODIPY is more readily accepted by folate receptor-positive CT26 cancer cells and provides a superior fluorescence "off-on" signal under hypoxic conditions than the controls. Based on the findings of this study, we propose that fol-BODIPY may serve as a tumor-targeting, hypoxia-activatable probe that allows for direct cancer monitoring both in vitro and in vivo.

Active colorimetric lipid-coated polyaniline nanoparticles for redox state sensing in cancer cells.

Herein, lipid-coated polyaniline (LiPAni) nanoparticles were fabricated to monitor the redox state of cancer cells. To confirm the characteristics of LiPAni, we firstly analyzed the size and chemical structures of the LiPAni nanoparticles. The absorbance properties of the LiPAni nanoparticles were observed to vary with the pH conditions. Furthermore, cell viability tests conducted with breast cancer cell lines showed that the cell viability of the cells with LiPAni nanoparticles was dramatically increased compared to those with the Tween80-coated polyaniline nanoparticles (TPAni) as a control. Subsequently, the colors of the LiPAni nanoparticles were observed and analyzed using spectroscopic methods. Finally, in order to investigate the more accurate sensing of the redox state using the color changes of the LiPAni nanoparticles with cancer cell lines, dark field microscopic images and scattering spectra were recorded at the single nanoparticle scale. For the TPAni nanoparticles, there was only a change in brightness and no change in color, but for the LiPAni nanoparticles, there was a change of color from yellow to pink in the dark field images.

Multimodal cellular redox nanosensors based on self-doped polyaniline nanocomposites.

We have successfully fabricated a nanocomposite, which is composed of polyaniline (PAni) and pyrene butyric acid (Pyba) via a solvent shift method, which was self-doped at a neutral pH value. This PAni nanocomposite can act as a fine nanoagent expressing absorbance, fluorescence, and Raman properties according to the surrounding pH values.

Cell-mimic polymersome-shielded islets for long-term immune protection of neonatal porcine islet-like cell clusters.

Although islet cell transplantation has emerged as a promising treatment for type 1 diabetes, it remains an unmet clinical application due to the need for immunosuppression to prevent islet elimination and autoimmunity. To solve these problems, we developed novel nanoencapsulation of neonatal porcine islet-like cell clusters (NPCCs) with cell-mimic polymersomes (PSomes) based on PEG-b-PLA (poly(ethylene glycol)-b-poly(dl-lactic acid)). To accomplish this, we first formulated NHS-, NH2-, COOH-, and m(methoxy)-PSomes. This coating utilizes interactions involving NPCC surfaces and PSomes that have covalent bonds, electrostatic interactions, and hydrogen bonds. We extended the range of applicability by comparing the binding affinity of electrostatic attraction and hydrogen bonding, as well as covalent bonds. Our protocol can be used as an efficient hydrogen bonding method because it reduces cell membrane damage as well as the use of covalent bonding methods. We verified the selective permeability of NHS-, NH2-, COOH-, and m-PSome-shielded NPCCs. Furthermore, we showed that a novel nanoencapsulation did not affect insulin secretion from NPCCs. This study offers engineering advances in islet encapsulation technologies to be used for cell-based transplantation therapies.

Dengue Virus-Polymersome Hybrid Nanovesicles for Advanced Drug Screening Using Real-Time Single Nanoparticle-Virus Tracking.

Dengue virus (DENV) is a major infectious viral pathogen that affects millions of individuals worldwide every year, causing a potentially fatal syndrome, while no commercial antiviral drugs are yet available. To develop an antiviral against dengue fever, it is necessary to understand the relationship between DENV and host cells, which could provide a basis for viral dynamics and identification of inhibitory drug targets. In this study, we designed DiD-loaded and BODIPY-ceramide-encapsulated DENV-polymersome hybrid nanovesicles (DENVSomes) prepared by an extrusion method, which trigger red fluorescence in the endosome and green in the Golgi. DENVSome monitors the dynamics of host cell-virus interaction and tracking in living cells with novel state-of-the-art imaging technologies that show images at high resolution. Also, DENVSome can be exploited to screen whether candidate antiviral drugs interact with DENVs. Consequently, we successfully demonstrated that DENVSome is an efficient tool for tracking and unraveling the mechanisms of replication and drug screening for antiviral drugs of DENV.

Performance evaluation of a small animal PET scanner a high level of multiplexing and charge-signal transmission.

Small animal positron emission tomography (PET) is a noninvasive imaging modality that enables in vivo imaging and quantification of the biological processes of small experimental animals. We have developed a small animal PET that utilizes a high-resolution multiplexed readout and charge signal transmission (CST) method. The small animal PET was composed of six detector blocks consisting of SiPMs and LYSO arrays. Six detector blocks were mounted on a PET gantry having an inner diameter of 76 mm, outer diameter of 112 mm, and axial length of 40.8 mm. The charge signals of SiPM output were transmitted to the input of multiplexed readout using 4 m flexible flat cables. The multiplexed readout was composed of six main boards, each of which included 36 detector boards, to reduce the number of readout channels by a factor of 36, with a multiplexing ratio of 144:4. The performance of the small animal PET was evaluated using NEMA NU 4-2008 standards, and its imaging capability was demonstrated by in vivo mouse imaging studies. The average energy and time resolutions were 13.2% ± 0.3% and 3.8 ns, respectively. The spatial resolution at the center of the transaxial FOV was 1.1 mm, and the peak sensitivity at the center of the axial FOV was 1.5%. The peak noise equivalent count (NEC) rate and scatter fraction were 21.1 kcps at 18.2 MBq and 21%, respectively. The acquired images demonstrated high quality tracer uptake patterns of small experimental animals. The results of performance evaluation and animal imaging indicate that the small animal PET developed in this study can provide high-quality small animal imaging with cost-effectiveness and compactness.

Anchored protease-activatable polymersomes for molecular diagnostics of metastatic cancer cells.

Real-time quantitative and qualitative analyses of metastasis-associated proteases are critical for precise diagnosis and novel therapeutic treatment of advanced cancers. However, conventional methods based on DNA, peptides, and proteins require sophisticated chemistry and additional processes to expose detection moieties, and they lack elements of temporal control, which limit their applicability. We designed unique protease-activatable polymersomes (PeptiSomes) for high sensitivity, in situ quantitative analysis of activating membrane-type 1 matrix metalloproteinases (MT1-MMP, MMP14). To do this, we first synthesized an amphiphilic block polymer-peptide and a copolypeptide based on mPEG-b-pLeu and MT1-peptide-b-pLeu, respectively. Amphiphilic self-assembled PeptiSomes in water were capable of disassembling and releasing the encapsulated self-quenched fluorescence dye (calcein) via enzymatic activation by MT1-MMP. Our PeptiSome system may potentially prevent the initiation and progression of cancer metastasis. Furthermore, the PeptiSome approach described here is likely to facilitate the development of rapid protease assay techniques and further extend the role of proteases as metastasis indicators and therapeutic targets.

Nanovesicle-mediated systemic delivery of microRNA-34a for CD44 overexpressing gastric cancer stem cell therapy.

The cancer stem cell (CSC) hypothesis postulates that cancer cells overexpressing CD44 are marked as CSCs that cause tumorigenesis and recurrence. This hypothesis suggests that CD44 is a potential therapeutic target that can interfere with CSCs qualities. MicroRNA-34a (miR-34a) is a promising candidate for CD44 repression-based cancer therapy as it has been reported to inhibit proliferation, metastasis, and survival of CD44-positive CSCs. Here, we used nanovesicles containing PLI/miR complexes (NVs/miR) to systemically deliver miR-34a and induce miR-34a-triggered CD44 suppression in orthotopically and subcutaneously implanted tumors in nude mice. Poly(l-lysine-graft-imidazole) (PLI) condenses miRs and is functionally modified to deliver miRs to the site of action by buffering effect of imidazole residues under endosomal pH. Indeed, NVs/miR consisting of PEGylated lipids enveloping PLI/miR complexes greatly reduced inevitable toxicity of polycations by compensating their surface charge and markedly improved their in vivo stability and accumulation to tumor tissue compared to PLI/miR polyplexes. Our NVs-mediated miR-34a delivery system specifically increased endogenous target miR levels, thereby attenuating proliferation and migration of gastric cancer cells by repressing the expression of CD44 with decreased levels of Bcl-2, Oct 3/4 and Nanog genes. Our strategy led to a greater therapeutic outcome than PLI-based delivery with highly selective tumor cell death and significantly delayed tumor growth in CD44-positive tumor-bearing mouse models, thus providing a fundamental therapeutic window for CSCs.

Imidazolized magnetic nanovectors with endosome disrupting moieties for the intracellular delivery and imaging of siRNA.

The development of a synchronized delivery and imaging system for small interfering RNA (siRNA) is required for the clinical application of RNA interference (RNAi) in cancer treatment. Herein, we report a pH-responsive, magnetic nanoparticle-based siRNA delivery system that can facilitate the safe and efficient delivery and visualization of therapeutic siRNA by high-resolution magnetic resonance (MR) imaging. Cationic poly-l-lysine-graft-imidazole (PLI) with a reactive silane moiety was stably immobilized onto the surface of the assembled manganese ferrite nanoparticles (MFs) through an emulsion process, ensuring high water solubility, enhanced MR contrast effect, and endosome-disrupting functionality. The synthesized nanovectors were then complexed with siRNA targeting the CD44 gene via electrostatic interactions to verify the specific gene-silencing effect. The imidazolized magnetic nanovector (ImMNV) architectures developed here facilitated improved cellular internalization and exhibited a high level in vitro downregulation compared to non-imidazolized MNVs in metastatic breast cancer cells.

Chitosan-based intelligent theragnosis nanocomposites enable pH-sensitive drug release with MR-guided imaging for cancer therapy.

Smart drug delivery systems that are triggered by environmental conditions have been developed to enhance cancer therapeutic efficacy while limiting unwanted effects. Because cancer exhibits abnormally high local acidities compared to normal tissues (pH 7.4) due to Warburg effects, pH-sensitive systems have been researched for effective cancer therapy. Chitosan-based intelligent theragnosis nanocomposites, N-naphthyl-O-dimethymaleoyl chitosan-based drug-loaded magnetic nanoparticles (NChitosan-DMNPs), were developed in this study. NChitosan-DMNPs are capable of pH-sensitive drug release with MR-guided images because doxorubicin (DOX) and magnetic nanocrystals (MNCs) are encapsulated into the designed N-naphthyl-O-dimethymaleoyl chitosan (N-nap-O-MalCS). This system exhibits rapid DOX release as acidity increases, high stability under high pH conditions, and sufficient capacity for diagnosing and monitoring therapeutic responses. These results demonstrate that NChitosan-DMNPs have potential as theragnosis nanocomposites for effective cancer therapy.

3-D surface rendering of myocardial SPECT images segmented by level set technique.

SPECT(single photon emission computed tomography) myocardial imaging is a diagnosis technique that images the region of interest and examines any change induced by disease using a computer after injects intravenously a radiopharmaceutical drug emitting gamma ray and the drug has dispersed evenly in the heart . Myocardial perfusion imaging, which contains functional information, is useful for non-invasive diagnosis of myocardial disease but noises caused by physical factors and low resolution give difficulty in reading the images. In order to help reading myocardial images, this study proposed a method that segments myocardial images and reconstructs the segmented region into a 3D image. To resolve difficulty in reading, we segmented the left ventricle, the region of interest, using a level set and modeled the segmented region into a 3D image.