Lysosomal-targeted doxorubicin delivery using RBC-derived vesicles to overcome drug-resistant cancer through mitochondrial-dependent cell death.

Multidrug resistance (MDR) is a major challenge in cancer chemotherapy. Nanoparticles as drug delivery systems (DDSs) show promise for MDR cancer therapy. However, current DDSs require sophisticated design and construction based on xenogeneic nanomaterials, evoking feasibility and biocompatibility concerns. Herein, a simple but versatile biological DDS (bDDS) composed of human red blood cell (RBC)-derived vesicles (RDVs) with excellent biocompatibility was surface-linked with doxorubicin (Dox) using glutaraldehyde (glu) to form Dox-gluRDVs that remarkably suppressed MDR in uterine sarcoma through a lysosomal-mitochondrial axis-dependent cell death mechanism. Dox-gluRDVs can efficiently deliver and accumulate Dox in lysosomes, bypassing drug efflux transporters and facilitating cellular uptake and retention of Dox in drug-resistant MES-SA/Dx5 cells. The transfer of lysosomal calcium to the mitochondria during mitochondria-lysosome contact due to lysosomal Dox accumulation may result in mitochondrial ROS overproduction, mitochondrial membrane potential loss, and activation of apoptotic signaling for the superior anti-MDR activity of Dox-gluRDVs in vitro and in vivo. This work highlights the great promise of RDVs to serve as a bDDS of Dox to overcome MDR cancers but also opens up a reliable strategy for lysosomal-mitochondrial axis-dependent cell death for fighting against other inoperable cancers.

Hydrolysis of Gluten-Derived Celiac Disease-Triggering Peptides across a Broad pH Range by RmuAP1: A Novel Aspartic Peptidase Isolated from Rhodotorula mucilaginosa.

An aspartate peptidase with proteolytic activity toward gluten was identified from an isolated red yeast Rhodotorula mucilaginosa strain. This peptidase consists of 425 amino acids, comprising an N-terminal signal peptide, a propeptide, and a C-terminal catalytic domain. The catalytic domain, termed RmuAP1CD, could be secreted by the recombinant oleaginous yeast Yarrowia lipolytica, whose genome contains the expression cassette for RmuAP1CD. RmuAP1CD exhibited optimum activity at pH 2.5 when acting on bovine serum albumin. Moreover, it facilitated the hydrolysis of gluten-derived immunogenic peptides (GIPs), which are responsible for triggering celiac disease symptoms, across a pH range of 3.0-6.0. The preferred cleavage sites are P-Q-Q-↓-P-Q in the 26-mer and P-Q-L-↓-P-Y in the 33-mer GIPs. Conversely, porcine pepsin cannot hydrolyze these two GIPs. The ability of RmuAP1CD to degrade GIPs under acidic conditions of the stomach indicates its potential as a viable oral enzyme therapy for celiac disease.

A Dual Concentration-Tailored Cytokine-Chemo Nanosystem to Alleviate Multidrug Resistance and Redirect Balance of Cancer Proliferation and Apoptosis.

Background: Cancer multidrug resistance (MDR) is an important factor that severely affects the chemotherapeutic efficacy. Among various methods to bypass MDR, usage of cytokines, such as tumor necrosis factor alpha (TNFα) is attractive, which exerts antitumor effects of immunotherapeutic response and apoptotic/proinflammatory pathways. Nevertheless, the challenges remain how to implement targeted delivery of TNFα to reduce toxicity and manifest the involved signaling mechanism that subdues MDR. Methods: We synthesized a multifunctional nanosytem, in which TNFα covalently bound to doxorubicin (Dox)-loaded pH-responsive mesoporous silica nanoparticles (MSN) through bi-functional polyethylene glycol (TNFα-PEG-MSN-Hydrazone-Dox) as a robust design to overcome MDR. Results: The salient features of this nanoplatform are: 1) by judicious tailoring of TNFα concentration conjugated on MSN, we observed it could lead to a contrary effect of either proliferation or suppression of tumor growth; 2) the MSN-TNFα at higher concentration serves multiple functions, besides tumor targeting and inducer of apoptosis through extrinsic pathway, it inhibits the expression level of p-glycoprotein (P-gp), a cell membrane protein that functions as a drug efflux pump; 3) the enormous surface area of MSN provides for TNFα functionalization, and the nanochannels accommodate chemotherapeutics, Dox; 4) targeted intracellular release of Dox through the pH-dependent cleavage of hydrazone bonds induces apoptosis by the specific intrinsic pathway; and 5) TNFα-PEG-MSN-Hydrazone-Dox (MSN-Dox-TNFα) could infiltrate deep into the 3D spheroid tumor model through disintegration of tight junction proteins. When administered intratumorally in a Dox-resistant mouse tumor model, MSN-Dox-TNFα exhibited a synergistic therapeutic effect through the collective performances of TNFα and Dox. Conclusion: We hereby develop and demonstrate a multifunctional MSN-Dox-TNFα system with concentration-tailored TNFα that can abrogate the drug resistance mechanism, and significantly inhibit the tumor growth through both intrinsic and extrinsic apoptosis pathways, thus making it a highly potential nanomedicine translated in the treatment of MDR tumors.

Illuminating and Radiosensitizing Tumors with 2DG-Bound Gold-Based Nanomedicine for Targeted CT Imaging and Therapy.

Although radiotherapy is one of the most important curative treatments for cancer, its clinical application is associated with undesired therapeutic effects on normal or healthy tissues. The use of targeted agents that can simultaneously achieve therapeutic and imaging functions could constitute a potential solution. Herein, we developed 2-deoxy-d-glucose (2DG)-labeled poly(ethylene glycol) (PEG) gold nanodots (2DG-PEG-AuD) as a tumor-targeted computed tomography (CT) contrast agent and radiosensitizer. The key advantages of the design are its biocompatibility and targeted AuD with excellent sensitivity in tumor detection via avid glucose metabolism. As a consequence, CT imaging with enhanced sensitivity and remarkable radiotherapeutic efficacy could be attained. Our synthesized AuD displayed linear enhancement of CT contrast as a function of its concentration. In addition, 2DG-PEG-AuD successfully demonstrated significant augmentation of CT contrast in both in vitro cell studies and in vivo tumor-bearing mouse models. In tumor-bearing mice, 2DG-PEG-AuD showed excellent radiosensitizing functions after intravenous injection. Results from this work indicate that 2DG-PEG-AuD could greatly potentiate theranostic capabilities by providing high-resolution anatomical and functional images in a single CT scan and therapeutic capability.

Personalized Cancer Therapeutics Using Photoacoustic Imaging-Guided Sonodynamic Therapy.

Sonodynamic therapy (SDT) is a promising approach for cancer treatment that uses sonosensitizers (SNSs) to generate reactive oxygen species (ROS) in the presence of ultrasound (US). However, SDT is oxygen-dependent and requires an imaging tool to monitor the tumor microenvironment and guide treatment. Photoacoustic imaging (PAI) is a noninvasive and powerful imaging tool that offers high spatial resolution and deep tissue penetration. PAI can quantitatively assess tumor oxygen saturation (sO2) and guide SDT by monitoring time-dependent sO2 changes in the tumor microenvironment. Here, we discuss recent advances in PAI-guided SDT for cancer therapy. We discuss various exogenous contrast agents and nanomaterial-based SNSs developed for PAI-guided SDT. Additionally, combining SDT with other therapies, including photothermal (PTT) therapy, can enhance its therapeutic effect. However, the application of nanomaterial-based contrast agents in PAI-guided SDT for cancer therapy remains challenging due to the lack of simple designs, the need for extensive pharmacokinetic studies, and high production costs. Integrated efforts from researchers, clinicians, and industry consortia are necessary for the successful clinical translation of these agents and SDT for personalized cancer therapy. PAI-guided SDT shows the potential to revolutionize cancer therapy and improve patient outcomes, but further research is necessary to realize its full potential.

Sessile Trichomes Play Major Roles in Prey Digestion and Absorption, While Stalked Trichomes Function in Prey Predation in Byblis guehoi.

Carnivorous plants in the genus Byblis obtain nutrients by secreting viscous glue drops and enzymes that trap and digest small organisms. Here, we used B. guehoi to test the long-held theory that different trichomes play different roles in carnivorous plants. In the leaves of B. guehoi, we observed a 1:2.5:14 ratio of long-stalked, short-stalked, and sessile trichomes. We demonstrated that the stalked trichomes play major roles in the production of glue droplets, while the sessile trichomes secrete digestive enzymes, namely proteases and phosphatases. In addition to absorbing digested small molecules via channels/transporters, several carnivorous plants employ a more efficient system: endocytosis of large protein molecules. By feeding B. guehoi fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) to monitor protein transport, we found that sessile trichomes exhibited more endocytosis than long- and short-stalked trichomes. The uptaken FITC-BSA was delivered to the neighboring short epidermal cells in the same row as the sessile trichomes, then to the underlying mesophyll cells; however, no signals were detected in the parallel rows of long epidermis cells. The FITC control could be taken up by sessile trichomes but not transported out. Our study shows that B. guehoi has developed a well-organized system to maximize its food supply, consisting of stalked trichomes for prey predation and sessile trichomes for prey digestion. Moreover, the finding that sessile trichomes transfer large, endocytosed protein molecules to the underlying mesophyll, and putatively to the vascular tissues, but not laterally to the terminally differentiated epidermis, indicates that the nutrient transport system has evolved to maximize efficiency.

The Bph45 Gene Confers Resistance against Brown Planthopper in Rice by Reducing the Production of Limonene.

Brown planthopper (BPH), a monophagous phloem feeder, consumes a large amount of photoassimilates in rice and causes wilting. A near-isogenic line 'TNG71-Bph45' was developed from the Oryza sativa japonica variety 'Tainung 71 (TNG71) carrying a dominant BPH-resistance locus derived from Oryza nivara (IRGC 102165) near the centromere of chromosome 4. We compared the NIL (TNG71-Bph45) and the recurrent parent to explore how the Bph45 gene confers BPH resistance. We found that TNG71-Bph45 is less attractive to BPH at least partially because it produces less limonene. Chiral analysis revealed that the major form of limonene in both rice lines was the L-form. However, both L- and D-limonene attracted BPH when applied exogenously to TNG71-Bph45 rice. The transcript amounts of limonene synthase were significantly higher in TNG71 than in TNG71-Bph45 and were induced by BPH infestation only in the former. Introgression of the Bph45 gene into another japonica variety, Tainan 11, also resulted in a low limonene content. Moreover, several dominantly acting BPH resistance genes introduced into the BPH-sensitive IR24 line compromised its limonene-producing ability and concurrently decreased its attractiveness to BPH. These observations suggest that reducing limonene production may be a common resistance strategy against BPH in rice.

Industrialization's eye view on theranostic nanomedicine.

The emergence of nanomedicines (NMs) in the healthcare industry will bring about groundbreaking improvements to the current therapeutic and diagnostic scenario. However, only a few NMs have been developed into clinical applications due to a lack of regulatory experience with them. In this article, we introduce the types of NM that have the potential for clinical translation, including theranostics, multistep NMs, multitherapy NMs, and nanoclusters. We then present the clinical translational challenges associated with NM from the pharmaceutical industry's perspective, such as NMs' intrinsic physiochemical properties, safety, scale-up, lack of regulatory experience and standard characterization methods, and cost-effectiveness compared with their traditional counterparts. Overall, NMs face a difficult task to overcome these challenges for their transition from bench to clinical use.

Multimodal Magnetic Resonance and Photoacoustic Imaging of Tumor-Specific Enzyme-Responsive Hybrid Nanoparticles for Oxygen Modulation.

Multimodal imaging contrast agents for cancer that can not only perform diagnostic functions but also serve as tumor microenvironment-responsive biomaterials are encouraging. In this study, we report the design and fabrication of a novel enzyme-responsive T1 magnetic resonance imaging (MRI) contrast agent that can modulate oxygen in the tumor microenvironment via the catalytic conversion of H2O2 to O2. The T1 contrast agent is a core-shell nanoparticle that consists of manganese oxide and hyaluronic acid (HA)-conjugated mesoporous silica nanoparticle (HA-MnO@MSN). The salient features of the nanoparticle developed in this study are as follows: 1) HA serves as a targeting ligand for CD44-expressing cancer cells; 2) HA allows controlled access of water molecules to the MnO core via the digestion of enzyme hyaluronidase; 3) the generation of O2 bubbles in the tumor by consuming H2O2; and 4) the capability to increase the oxygen tension in the tumor. The r 1 relaxivity of HA-MnO@MSN was measured to be 1.29 mM-1s-1 at a magnetic field strength of 9.4 T. In vitro results demonstrated the ability of continuous oxygen evolution by HA-MnO@MSN. After intratumoral administration of HA-MnO@MSN to an HCT116 xenograft mouse model, T1 weighted MRI contrast was observed after 5 h postinjection and retained up to 48 h. In addition, in vivo photoacoustic imaging of HA-MnO@MSN demonstrated an increase in the tumor oxygen saturation over time after i. t. administration. Thus, the core-shell nanoparticles developed in this study could be helpful in tumor-targeted T1 MR imaging and oxygen modulation.

Assessment of Nanoparticle-Mediated Tumor Oxygen Modulation by Photoacoustic Imaging.

Photoacoustic imaging (PAI) is an invaluable tool in biomedical imaging, as it provides anatomical and functional information in real time. Its ability to image at clinically relevant depths with high spatial resolution using endogenous tissues as contrast agents constitutes its major advantage. One of the most important applications of PAI is to quantify tissue oxygen saturation by measuring the differential absorption characteristics of oxy and deoxy Hb. Consequently, PAI can be utilized to monitor tumor-related hypoxia, which is a crucial factor in tumor microenvironments that has a strong influence on tumor invasiveness. Reactive oxygen species (ROS)-based therapies, such as photodynamic therapy, radiotherapy, and sonodynamic therapy, are oxygen-consuming, and tumor hypoxia is detrimental to their efficacy. Therefore, a persistent demand exists for agents that can supply oxygen to tumors for better ROS-based therapeutic outcomes. Among the various strategies, NP-mediated supplemental tumor oxygenation is especially encouraging due to its physio-chemical, tumor targeting, and theranostic properties. Here, we focus on NP-based tumor oxygenation, which includes NP as oxygen carriers and oxygen-generating strategies to alleviate hypoxia monitored by PAI. The information obtained from quantitative tumor oxygenation by PAI not only supports optimal therapeutic design but also serves as a highly effective tool to predict therapeutic outcomes.

Efficient Hydrolysis of Gluten-Derived Celiac Disease-Triggering Immunogenic Peptides by a Bacterial Serine Protease from Burkholderia gladioli.

Celiac disease is an autoimmune disorder triggered by toxic peptides derived from incompletely digested glutens in the stomach. Peptidases that can digest the toxic peptides may formulate an oral enzyme therapy to improve the patients' health condition. Bga1903 is a serine endopeptidase secreted by Burkholderia gladioli. The preproprotein of Bga1903 consists of an N-terminal signal peptide, a propeptide region, and an enzymatic domain that belongs to the S8 subfamily. Bga1903 could be secreted into the culture medium when it was expressed in E. coli. The purified Bga1903 is capable of hydrolyzing the gluten-derived toxic peptides, such as the 33- and 26-mer peptides, with the preference for the peptide bonds at the carbonyl site of glutamine (P1 position). The kinetic assay of Bga1903 toward the chromogenic substrate Z-HPQ-pNA at 37 °C, pH 7.0, suggests that the values of Km and kcat are 0.44 ± 0.1 mM and 17.8 ± 0.4 s-1, respectively. The addition of Bga1903 in the wort during the fermentation step of beer could help in making gluten-free beer. In summary, Bga1903 is usable to reduce the gluten content in processed foods and represents a good candidate for protein engineering/modification aimed to efficiently digest the gluten at the gastric condition.

Fungicidal Activity of Volatile Organic Compounds Emitted by Burkholderia gladioli Strain BBB-01.

A Burkholderia gladioli strain, named BBB-01, was isolated from rice shoots based on the confrontation plate assay activity against several plant pathogenic fungi. The genome of this bacterial strain consists of two circular chromosomes and one plasmid with 8,201,484 base pairs in total. Pangenome analysis of 23 B. gladioli strains suggests that B. gladioli BBB-01 has the closest evolutionary relationship to B. gladioli pv. gladioli and B. gladioli pv. agaricicola. B. gladioli BBB-01 emitted dimethyl disulfide and 2,5-dimethylfuran when it was cultivated in lysogeny broth and potato dextrose broth, respectively. Dimethyl disulfide is a well-known pesticide, while the bioactivity of 2,5-dimethylfuran has not been reported. In this study, the inhibition activity of the vapor of these two compounds was examined against phytopathogenic fungi, including Magnaporthe oryzae, Gibberella fujikuroi, Sarocladium oryzae, Phellinus noxius and Colletotrichumfructicola, and human pathogen Candida albicans. In general, 2,5-dimethylfuran is more potent than dimethyl disulfide in suppressing the growth of the tested fungi, suggesting that 2,5-dimethylfuran is a potential fumigant to control plant fungal disease.

Annealing-modulated nanoscintillators for nonconventional X-ray activation of comprehensive photodynamic effects in deep cancer theranostics.

Photodynamic therapy (PDT), which involves the generation of reactive oxygen species (ROS) through interactions of a photosensitizer (PS) with light and oxygen, has been applied in oncology. Over the years, PDT techniques have been developed for the treatment of deep-seated cancers. However, (1) the tissue penetration limitation of excitation photon, (2) suppressed efficiency of PS due to multiple energy transfers, and (3) insufficient oxygen source in hypoxic tumor microenvironment still constitute major challenges facing the clinical application of PDT for achieving effective treatment. We present herein a PS-independent, ionizing radiation-induced PDT agent composed of yttrium oxide nanoscintillators core and silica shell (Y2O3:Eu@SiO2) with an annealing process. Our results revealed that annealed Y2O3:Eu@SiO2 could directly induce comprehensive photodynamic effects under X-ray irradiation without the presence of PS molecules. The crystallinity of Y2O3:Eu@SiO2 was demonstrated to enable the generation of electron-hole (e--h+) pairs in Y2O3 under ionizing irradiation, giving rise to the formation of ROS including superoxide, hydroxyl radical and singlet oxygen. In particular, combining Y2O3:Eu@SiO2 with fractionated radiation therapy increased radio-resistant tumor cell damage. Furthermore, photoacoustic imaging of tumors showed re-distribution of oxygen saturation (SO2) and reoxygenation of the hypoxia region. The results of this study support applicability of the integration of fractionated radiation therapy with Y2O3:Eu@SiO2, achieving synchronously in-depth and oxygen-insensitive X-ray PDT. Furthermore, we demonstrate Y2O3:Eu@SiO2 exhibited radioluminescence (RL) under X-ray irradiation and observed the virtually linear correlation between X-ray-induced radioluminescence (X-RL) and the Y2O3:Eu@SiO2 concentration in vivo. With the pronounced X-RL for in-vivo imaging and dosimetry, it possesses significant potential for utilization as a precision theranostics producing highly efficient X-ray PDT for deep-seated tumors.

Biodegradable Polymers for Gene-Delivery Applications.

Gene-based therapies have emerged as a new modality for combating a myriad of currently incurable diseases. However, the fragile nature of gene therapeutics has significantly hampered their biomedical applications. Correspondingly, the development of gene-delivery vectors is of critical importance for gene-based therapies. To date, a variety of gene-delivery vectors have been created and utilized for gene delivery. In general, they can be categorized into viral- and non-viral vectors. Due to safety issues associated with viral vectors, non-viral vectors have recently attracted much more research focus. Of these non-viral vectors, polymeric vectors, which have been preferred due to their low immunogenicity, ease of production, controlled chemical composition and high chemical versatility, have constituted an ideal alternative to viral vectors. In particular, biodegradable polymers, which possess advantageous biocompatibility and biosafety, have been considered to have great potential in clinical applications. In this context, the aim of this review is to introduce the recent development and progress of biodegradable polymers for gene delivery applications, especially for their chemical structure design, gene delivery capacity and additional biological functions. Accordingly, we first define and categorize biodegradable polymers, followed by describing their corresponding degradation mechanisms. Various types of biodegradable polymers resulting from natural and synthetic polymers will be introduced and their applications in gene delivery will be examined. Finally, a future perspective regarding the development of biodegradable polymer vectors will be given.

Precision control of the large-scale green synthesis of biodegradable gold nanodandelions as potential radiotheranostics.

Herein, we report a new type of biodegradable, high surface-area gold nanodandelions (GNDs). This report possesses important features and some are the first of its kind: (1) the large scale green synthesis of GNDs with high monodispersity and a circa 100% yield with consistent chemistry, manufacturing and controls (CMC); (2) cellular/physiological degradability of GNDs leading to its disassembly into debris, which is indicative of the potential for possible body clearance; (3) precision control of the chemicophysical properties of the GNDs including shape, petal number and size, all can be judiciously fine-tuned by the synthetic parameters; (4) highly efficient radiotheranostics of GNDs encompassing better enhanced computed tomography (CT) contrast and pronounced X-ray induced reactive oxygen species (ROS) generation than conventional spherical gold nanoparticles (AuNP). It is noteworthy that the GNDs demonstrate a unique combinational effect of radiosensitization (production of superoxide anions and hydroxyl radicals) and type II photodynamic interaction (generation of singlet oxygen). Given the above, our reported GNDs are promising in clinical translation as radiotheranostics.

Proliferating Cell Nuclear Antigen Suppresses RNA Replication of Bamboo Mosaic Virus through an Interaction with the Viral Genome.

Bamboo mosaic virus (BaMV), a member of the Potexvirus genus, has a monopartite positive-strand RNA genome on which five open reading frames (ORFs) are organized. ORF1 encodes a 155-kDa nonstructural protein (REPBaMV) that plays a core function in replication/transcription of the viral genome. To find out cellular factors modulating the replication efficiency of BaMV, a putative REPBaMV-associated protein complex from Nicotiana benthamiana leaf was isolated on an SDS-PAGE gel, and a few proteins preferentially associated with REPBaMV were identified by tandem mass spectrometry. Among them, proliferating cell nuclear antigen (PCNA) was particularly noted. Overexpression of PCNA strongly suppressed the accumulation of BaMV coat protein and RNAs in leaf protoplasts. In addition, PCNA exhibited an inhibitory effect on BaMV polymerase activity. A pulldown assay confirmed a binding capability of PCNA toward BaMV genomic RNA. Mutations at D41 or F114 residues, which are critical for PCNA to function in nuclear DNA replication and repair, disabled PCNA from binding BaMV genomic RNA as well as suppressing BaMV replication. This suggests that PCNA bound to the viral RNA may interfere with the formation of a potent replication complex or block the replication process. Interestingly, BaMV is almost invisible in the newly emerging leaves where PCNA is actively expressed. Accordingly, PCNA is probably one of the factors restricting the proliferation of BaMV in young leaves. Foxtail mosaic virus and Potato virus X were also suppressed by PCNA in the protoplast experiment, suggesting a general inhibitory effect of PCNA on the replication of potexviruses.IMPORTANCE Knowing the dynamic interplay between plant RNA viruses and their host is a basic step toward first understanding how the viruses survive the plant defense mechanisms and second gaining knowledge of pathogenic control in the field. This study found that plant proliferating cell nuclear antigen (PCNA) imposes a strong inhibition on the replication of several potexviruses, including Bamboo mosaic virus, Foxtail mosaic virus, and Potato virus X Based on the tests on Bamboo mosaic virus, PCNA is able to bind the viral genomic RNA, and this binding is a prerequisite for the protein to suppress the virus replication. This study also suggests that PCNA plays an important role in restricting the proliferation of potexviruses in the rapidly dividing tissues of plants.

Seeing Better and Going Deeper in Cancer Nanotheranostics.

Biomedical imaging modalities in clinical practice have revolutionized oncology for several decades. State-of-the-art biomedical techniques allow visualizing both normal physiological and pathological architectures of the human body. The use of nanoparticles (NP) as contrast agents enabled visualization of refined contrast images with superior resolution, which assists clinicians in more accurate diagnoses and in planning appropriate therapy. These desirable features are due to the ability of NPs to carry high payloads (contrast agents or drugs), increased in vivo half-life, and disease-specific accumulation. We review the various NP-based interventions for treatments of deep-seated tumors, involving "seeing better" to precisely visualize early diagnosis and "going deeper" to activate selective therapeutics in situ.

Highly sensitive electron paramagnetic resonance nanoradicals for quantitative intracellular tumor oxymetric images.

Purpose: Tumor oxygenation is a critical parameter influencing the efficacy of cancer therapy. Low levels of oxygen in solid tumor have been recognized as an indicator of malignant progression and metastasis, as well as poor response to chemo- and radiation therapy. Being able to measure oxygenation for an individual's tumor would provide doctors with a valuable way of identifying optimal treatments for patients. Methods: Electron paramagnetic resonance imaging (EPRI) in combination with an oxygen-measuring paramagnetic probe was performed to measure tumor oxygenation in vivo. Triarylmethyl (trityl) radical exhibits high specificity, sensitivity, and resolution for quantitative measurement of O2 concentration. However, its in vivo applications in previous studies have been limited by the required high dosage, its short half-life, and poor intracellular permeability. To address these limitations, we developed high-capacity nanoformulated radicals that employed fluorescein isothiocyanate-labeled mesoporous silica nanoparticles (FMSNs) as trityl radical carriers. The high surface area nanostructure and easy surface modification of physiochemical properties of FMSNs enable efficient targeted delivery of highly concentrated, nonself-quenched trityl radicals, protected from environmental degradation and dilution. Results: We successfully designed and synthesized a tumor-targeted nanoplatform as a carrier for trityl. In addition, the nanoformulated trityl does not affect oxygen-sensing capacity by a self-relaxation or broadening effect. The FMSN-trityl exhibited high sensitivity/response to oxygen in the partial oxygen pressure range from 0 to 155 mmHg. Furthermore, MSN-trityl displayed outstanding intracellular oxygen mapping in both in vitro and in vivo animal studies. Conclusion: The highly sensitive nanoformulated trityl spin probe can profile intracellular oxygen distributions of tumor in a real-time and quantitative manner using in vivo EPRI.

A novel mouse model of sporadic colon cancer induced by combination of conditional Apc genes and chemical carcinogen in the absence of Cre recombinase.

Although valuable insights into colon cancer biology have been garnered from human colon cancer cell lines and primary colonic tissues, and animal studies using human colon cancer xenografts, immunocompetent mouse models of spontaneous or chemically induced colon cancer better phenocopy human disease. As most sporadic human colon tumors present adenomatous polyposis coli (APC) gene mutations, considerable effort has gone into developing mice that express mutant Apc alleles that mimic human colon cancer pathogenesis. A serious limitation of many of these Apc-mutant murine models, however, is that these mice develop numerous tumors in the small intestine but few, if any, in the colon. In this work, we examined three spontaneous mouse models of colon tumorigenesis based upon the widely used multiple intestinal neoplasia (Min) mouse: mice with either constitutive or conditional Apc mutations alone or in combination with caudal-related homeobox transcription factor CDX2P-Cre transgene - either with or without exposure to the potent colon carcinogen azoxymethane. Using the CDX2 promoter to drive Cre recombinase transgene expression effectively inactivated Apc in colonocytes, creating a model with earlier tumor onset and increased tumor incidence/burden, but without the Min mouse model's small intestine tumorigenesis and susceptibility to intestinal perforation/ulceration/hemorrhage. Most significantly, azoxymethane-treated mice with conditional Apc expression, but absent the Cre recombinase gene, demonstrated nearly 50% tumor incidence with two or more large colon tumors per mouse of human-like histology, but no small intestine tumors - unlike the azoxymethane-resistant C57BL/6J-background Min mouse model. As such this model provides a robust platform for chemoprevention studies.

Microwave-Synthesized Platinum-Embedded Mesoporous Silica Nanoparticles as Dual-Modality Contrast Agents: Computed Tomography and Optical Imaging.

Nanoparticle-based imaging contrast agents have drawn tremendous attention especially in multi-modality imaging. In this study, we developed mesoporous silica nanoparticles (MSNs) for use as dual-modality contrast agents for computed tomography (CT) and near-infrared (NIR) optical imaging (OI). A microwave synthesis for preparing naked platinum nanoparticles (nPtNPs) on MSNs (MSNs-Pt) was developed and characterized with physicochemical analysis and imaging systems. The high density of nPtNPs on the surface of the MSNs could greatly enhance the CT contrast. Inductively coupled plasma mass spectrometry (ICP-MS) revealed the MSNs-Pt compositions to be ~14% Pt by weight and TEM revealed an average particle diameter of ~50 nm and covered with ~3 nm diameter nPtNPs. To enhance the OI contrast, the NIR fluorescent dye Dy800 was conjugated to the MSNs-Pt nanochannels. The fluorescence spectra of MSNs-Pt-Dy800 were very similar to unconjugated Dy800. The CT imaging demonstrated that even modest degrees of Pt labeling could result in substantial X-ray attenuation. In vivo imaging of breast tumor-bearing mice treated with PEGylated MSNs-Pt-Dy800 (PEG-MSNs-Pt-Dy800) showed significantly improved contrasts in both fluorescence and CT imaging and the signal intensity within the tumor retained for 24 h post-injection.