Enhanced and selective delivery of enzyme therapy to 9L-glioma tumor via magnetic targeting of PEG-modified, β-glucosidase-conjugated iron oxide nanoparticles

SPION and doxorubicin-loaded polymeric nanocarriers for glioblastoma theranostics

Glioma is a type of cancer with a very poor prognosis with a survival of around 15 months in the case of glioblastoma multiforme (GBM). In order to advance in personalized medicine, we developed polymeric nanoparticles (PNP) loaded with both SPION (superparamagnetic iron oxide nanoparticles) and doxorubicin (DOX). The former being used for its potential to accumulate the PNP in the tumor under a strong magnetic field and the later for its therapeutic potential. The emulsion solvent and evaporation method was selected to develop monodisperse PNP with high loading efficiency in both SPION and DOX. Once injected in mice, a significant accumulation of the PNP was observed within the tumoral tissue under static magnetic field as observed by MRI leading to a reduction of tumor growth rate.

Targeted delivery of β-glucosidase-loaded magnetic nanoparticles: effect of external magnetic field duration and intensity

Aim: The effect of applied magnetic field duration and intensity on the delivery of β-glucosidase-loaded magnetic nanoparticles was evaluated. Materials & methods: The prepared β-glucosidase-loaded magnetic nanoparticles were targeted to subcutaneous tumors with an external magnetic field. Iron concentration and enzyme activity in tumor tissue were analyzed via electron spin resonance detection, Prussian blue staining and enzyme activity measurement. Results: The increase in magnetic nanoparticles quantity and enzyme activity in tumor tissue was not synchronous with the magnetic targeting duration. In addition, accumulation of magnetic nanoparticles and the increase in enzyme activity were not synchronous with the magnetic field intensity. Conclusion: The results suggested that appropriate magnetic field conditions should be considered for targeted delivery of bioactivity proteins based on magnetic nanoparticles.

Biomimetic Membrane-Structured Nanovesicles Carrying a Supramolecular Enzyme to Cure Lung Cancer

Platforms for enzyme delivery must simultaneously have plasma stability, high catalytic activity, and low/no immunogenicity of the enzyme. Here, we designed a novel biomimetic membrane-structured nanovesicle (BNV) to efficiently carry supramolecular enzymes to meet the above requirements. We complexed l-asparaginase (Aase) with hydroxypropyl-β-cyclodextrin (HPCD) to form a supramolecular amphiphile (AS) by self-assembly via noncovalent reversible interactions. We then used the first synthesized polyethylene glycol (PEG 2 kDa)-decorated hyaluronan (12 kDa) and HPCD to self-assemble a semipermeable biomimetic membrane-structured nanovesicle (BNV) together with AS loading. As compared to native Aase, AS@BNV exhibited superior catalytic activity preservation, improved catalytic activity, better pharmacokinetics in rats, enhanced cytotoxic effects, increased antitumor efficacy, and decreased side effects. The underlying mechanisms, such as the autophagy inhibition action against tumor cells, protein-protein docking of the interaction between Aase-serum albumin, and decreased hepatic enzymatic activity, were investigated. This approach paves the way for new types of powerful biomimetic-, supramolecular-, and nanocarrier-based enzymatic therapies.

Magnetically Directed Enzyme/Prodrug Prostate Cancer Therapy Based on β-Glucosidase/Amygdalin

Background

β-Glucosidase (β-Glu) can activate amygdalin to kill prostate cancer cells, but the poor specificity of this killing effect may cause severe general toxicity in vivo, limiting the practical clinical application of this approach.

Materials and Methods

In this study, starch-coated magnetic nanoparticles (MNPs) were successively conjugated with β-Glu and polyethylene glycol (PEG) by chemical coupling methods. Cell experiments were used to confirm the effects of immobilized β-Glu on amygdalin-mediated prostate cancer cell death in vitro. Subcutaneous xenograft models were used to carry out the targeting experiment and magnetically directed enzyme/prodrug therapy (MDEPT) experiment in vivo.

Results

Immobilized β-Glu activated amygdalin-mediated prostate cancer cell death. Tumor-targeting studies showed that PEG modification increased the accumulation of β-Glu-loaded nanoparticles in targeted tumor tissue subjected to an external magnetic field and decreased the accumulation of the nanoparticles in the liver and spleen. Based on an enzyme activity of up to 134.89 ± 14.18mU/g tissue in the targeted tumor tissue, PEG-β-Glu-MNP/amygdalin combination therapy achieved targeted activation of amygdalin and tumor growth inhibition in C57BL/6 mice bearing RM1 xenografts. Safety evaluations showed that this strategy had some impact on liver and heart function but did not cause obvious organ damage.

Conclusion

All findings indicate that this magnetically directed enzyme/prodrug therapy strategy has the potential to become a promising new approach for targeted therapy of prostate cancer.

Nanoparticle corona artefacts derived from specimen preparation of particle suspensions

Progress in the implementation of nanoparticles for therapeutic applications will accelerate with an improved understanding of the interface between nanoparticle surfaces and the media they are dispersed in. We examine this interface by analytical scanning transmission electron microscopy and show that incorrect specimen preparation or analysis can induce an artefactual, nanoscale, calcium phosphate-rich, amorphous coating on nanoparticles dispersed in cell culture media. We report that this ionic coating can be induced on five different types of nanoparticles (Au, BaTiO3, ZnO, TiO2 and Fe2O3) when specimen preparation causes a significant rise in pH above physiological levels. Such a pH change reduces ionic solubility in the suspending media to permit precipitation of calcium phosphate. Finally, we demonstrate that there is no indication of a calcium-phosphorus-rich coating on BaTiO3 nanoparticles suspended in culture media when prepared without alteration of the pH of the suspending media and imaged by cryo-STEM. Therefore we recommend that future reports utilising nanoparticles dispersed in cell culture media monitor and report the pH of suspensions during sample preparation.

PEG modification enhances the in vivo stability of bioactive proteins immobilized on magnetic nanoparticles

OBJECTIVE

To increase the in vivo stability of bioactive proteins via optimized loading methods.

RESULTS

β-Glucosidase (β-Glu), as a model protein, was immobilized on magnetic nanoparticles(denoted as MNP-β-Glu) by chemical coupling methods and was further modified by poly(ethylene glycol) (PEG) molecules (denoted as MNP-β-Glu-PEG) to increase its stability. The physicochemical properties of the as-prepared nanohybrids, including the particle size, zeta potential, and enzyme activity, were well characterized. The proper MNP/β-Glu feed ratio was important for optimizing the particle size. Analysis of enzyme activity showed that the stability of immobilized β-Glu compared with free β-Glu was lower in deionized water and higher in blood serum at 37 °C. MNP-β-Glu-PEG retained 77.9% of the initial activity within 30 days at 4 °C, whereas the free enzyme retained only 58.2%. Pharmacokinetic studies of Sprague-Dawley (SD) rats showed that the MNP-β-Glu-PEG group retained a higher enzyme activity in vivo (41.46% after 50 min) than the MNP-β-Glu group (0.03% after 50 min) and the β-Glu group (0.37% after 50 min). Moreover, in contrast to the MNP-β-Glu group, the enzyme activity was not fully synchronous with the decrease in the Fe concentration in the MNP-β-Glu-PEG group.

CONCLUSIONS

All findings indicated that the method of immobilization on magnetic nanoparticles and PEG modification is promising for the application of bioactive proteins in vivo.

Immobilization of β-Glucosidase from Thermatoga maritima on Chitin-functionalized Magnetic Nanoparticle via a Novel Thermostable Chitin-binding Domain

Enzyme immobilization is a powerful tool not only as a protective agent against harsh reaction conditions but also for the enhancement of enzyme activity, stability, reusability, and for the improvement of enzyme properties as well. Herein, immobilization of β-glucosidase from Thermotoga maritima (Tm-β-Glu) on magnetic nanoparticles (MNPs) functionalized with chitin (Ch) was investigated. This technology showed a novel thermostable chitin-binding domain (Tt-ChBD), which is more desirable in a wide range of large-scale applications. This exclusive approach was fabricated to improve the Galacto-oligosaccharide (GOS) production from a cheap and abundant by-product such as lactose through a novel green synthesis route. Additionally, SDS-PAGE, enzyme activity kinetics, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) revealed that among the immobilization strategies for Thermotoga maritime-β-Glucosidase thermostable chitin-binding domain (Tm-β-Glu-Tt-ChBD) on the attractive substrate; Ch-MNPs had the highest enzyme binding capacity and GOS production ratio when compared to the native enzyme. More interestingly, a magnetic separation technique was successfully employed in recycling the immobilized Tm-β-Glu for repetitive batch-wise GOS without significant loss or reduction of enzyme activity. This immobilization system displayed an operative stability status under various parameters, for instance, temperature, pH, thermal conditions, storage stabilities, and enzyme kinetics when compared with the native enzyme. Conclusively, the GOS yield and residual activity of the immobilized enzyme after the 10^th cycles were 31.23% and 66%, respectively. Whereas the GOS yield from native enzyme synthesis was just 25% after 12 h in the first batch. This study recommends applying Tt-ChBD in the immobilization process of Tm-β-Glu on Ch-MNPs to produce a low-cost GOS as a new eco-friendly process besides increasing the biostability and efficiency of the immobilized enzyme.

Co-encapsulation of superparamagnetic nanoparticles and doxorubicin in PLGA nanocarriers: Development, characterization and in vitro antitumor efficacy in glioma cells

With a very poor prognosis and no clear etiology, glioma is the most aggressive cancer in the brain. Thanks to its versatility, nanomedicine is a promising option to overcome the limitations on chemotherapy imposed by the blood brain barrier (BBB). The objective of this paper was to obtain monitored tumor-targeted therapeutic nanoparticles (NPs). To that end, theranostic surfactant-coated polymer poly-Lactic-co-Glycolic Acid (PLGA) nanoplatform encapsulating doxorubicin hydrochloride (DOX) and superparamagnetic iron oxide NPs (SPIONs) were developed. Different non-ionic surfactants known as BBB crossing enhancers (Tween 80, Brij-35, Pluronic F68 or Vitamin E-TPGS) were used to develop 4 types of theranostic nanoplatforms, which were characterized in terms of size and morphology by DLS, TEM and STEM-HAADF analyses. Moreover, the 3-month stability test, the therapeutic efficacy against different glioma cell lines (U87-MG, 9L/LacZ and patient derived-neuronal stem cells) and the Magnetic Resonance Imaging (MRI) relaxivity were studied. Results showed that the synthesised nanoplatforms were stable at 4 °C after their lyophilization, being that of paramount importance to ensure a long-term stability in a future in vivo application. Furthermore, the theranostic nanoplatforms were efficient in the in vitro treatment of glioma cells, proving to have imaging efficacy as MRI contrast agents. Our results show an efficient loading of drugs and good value of the relaxivity. Therefore, the efficient theranostic hybrid nanoplatform developed here could be used to perform MRI-guided delivery of hydrophobic drugs.

Biodistribution and targeting properties of iron oxide nanoparticles for treatments of cancer and iron anemia disease

IONP (iron oxide nanoparticles) commercialized for treatments of iron anemia or cancer diseases can be administered at doses exceeding 1 g per patient, indicating their bio-compatibility when they are prepared in the right conditions. Various parameters influence IONP biodistribution such as nanoparticle size, hydrophobicity/hydrophilicity, surface charge, core composition, coating properties, route of administration, quantity administered, and opsonization. IONP biodistribution trends include their capture by the reticuloendothelial system (RES), accumulation in liver and spleen, leading to nanoparticle degradation by macrophages and liver Kupffer cells, possibly followed by excretion in feces. To result in efficient tumor treatment, IONP need to reach the tumor in a sufficiently large quantity, using: (i) passive targeting, i.e. the extravasation of IONP through the blood vessel irrigating the tumor, (ii) molecular targeting achieved by a ligand bound to IONP specifically recognizing a cell receptor, and (iii) magnetic targeting in which a magnetic field gradient guides IONP towards the tumor. As a whole, targeting efficacy is relatively similar for different targeting, yielding a percentage of injected IONP in the tumor of 5.10^-4% to 3%, 0.1% to 7%, and 5.10^-3% to 2.6% for passive, molecular, and magnetic targeting, respectively. For the treatment of iron anemia disease, IONP are captured by the RES, and dissolved into free iron, which is then made available for the organism. For the treatment of cancer, IONP either deliver chemotherapeutic drugs to tumors, produce localized heat under the application of an alternating magnetic field or a laser, or activate in a controlled manner a sono-sensitizer following ultrasound treatment.

Multifunctional doxorubicin-loaded magnetoliposomes with active and magnetic targeting properties

Multifunctional magnetoliposomes (MLs) with active and magnetic targeting potential are evaluated as platform systems for drug targeting applications. USPIO-encapsulating MLs are prepared by freeze drying/extrusion, decorated with one or two ligands for brain or cancer targeting (t-MLs), and actively loaded with Doxorubicin (DOX). MLs have mean diameters between 117 and 171 nm. Ligand attachment yields and DOX-loading efficiency are sufficiently high, 78-95% and 89-92%, respectively, while DOX loading and retention is not affected by co-entrapment of USPIOs, and USPIO loading/retention is not modulated by DOX. Attachment of ligands, also does not affect DOX or USPIO loading. Interestingly, MLs have high magnetophoretic mobility (MM) compared to free USPIOs, which is not affected by surface coating with PEG (up to 8 mol%), but is slightly reduced by Chol incorporation in their membrane, or when functional groups are immobilized on their surface. ML size, (directly related to number of USPIOs entrapped per vesicle), is the most important MM-determining factor. MM increases by 570% when ML size increases from 69 to 348 nm. Targeting potential of t-MLs is verified by enhanced: (i) transport across a cellular model of the blood-brain-barrier, and (ii) anti-proliferative effect towards B16 melanoma cells. The potential of further enhancing t-ML targeting magnetically is verified by additional enhancements of (i) and (ii), when experiments are performed under a permanent magnetic field.

Biodegradable Polymeric Nanoparticles for Therapeutic Cancer Treatments

Polymeric nanoparticles have tremendous potential to improve the efficacy of therapeutic cancer treatments by facilitating targeted delivery to a desired site. The physical and chemical properties of polymers can be tuned to accomplish delivery across the multiple biological barriers required to reach diverse subsets of cells. The use of biodegradable polymers as nanocarriers is especially attractive, as these materials can be designed to break down in physiological conditions and engineered to exhibit triggered functionality when at a particular location or activated by an external source. We present how biodegradable polymers can be engineered as drug delivery systems to target the tumor microenvironment in multiple ways. These nanomedicines can target cancer cells directly, the blood vessels that supply the nutrients and oxygen that support tumor growth, and immune cells to promote anticancer immunotherapy.

Glioma-targeted superparamagnetic iron oxide nanoparticles as drug-carrying vehicles for theranostic effects

Multifunctional nanoparticles capable of the specific delivery of therapeutics to diseased cells and the real-time imaging of these sites have the potential to improve cancer treatment through personalized therapy. In this study, we have proposed a multifunctional nanoparticle that integrate magnetic targeting, drug-carrier functionality and real-time MRI imaging capabilities in one platform for the theranostic treatment of tumors. The multifunctional nanoparticle was designed with a superparamagnetic iron oxide core and a multifunctional shell composed of PEG/PEI/polysorbate 80 (Ps 80) and was used to encapsulate DOX. DOX-loaded multifunctional nanoparticles (DOX@Ps 80-SPIONs) with a Dh of 58.0 nm, a zeta potential of 28.0 mV, and a drug loading content of 29.3% presented superior superparamagnetic properties with a saturation magnetization (Ms) of 24.1 emu g(-1). The cellular uptake of DOX@Ps 80-SPIONs by C6 cells under a magnetic field was significantly enhanced over that of free DOX in solution, resulting in stronger in vitro cytotoxicity. The real-time therapeutic outcome of DOX@Ps 80-SPIONs was easily monitored by MRI. Furthermore, the negative contrast enhancement effect of the nanoparticles was confirmed in glioma-bearing rats. Prussian blue staining and ex vivo DOX fluorescence assays showed that the magnetic Ps 80-SPIONs and encapsulated DOX were delivered to gliomas by imposing external magnetic fields, indicating effective magnetic targeting. Due to magnetic targeting and Ps 80-mediated endocytosis, DOX@Ps 80-SPIONs in the presence of a magnetic field led to the complete suppression of glioma growth in vivo at 28 days after treatment. The therapeutic mechanism of DOX@Ps 80-SPIONs acted by inducing apoptosis through the caspase-3 pathway. Finally, DOX@Ps 80-SPIONs' safety at therapeutic dosage was verified using pathological HE assays of the heart, liver, spleen, lung and kidney. Multifunctional SPIONs could be used as potential carriers for the theranostic treatment of CNS diseases.

Application of iron oxide nanoparticles in glioma imaging and therapy: from bench to bedside

Gliomas are the most common primary brain tumors and have a very dismal prognosis. However, recent advancements in nanomedicine and nanotechnology provide opportunities for personalized treatment regimens to improve the poor prognosis of patients suffering from glioma. This comprehensive review starts with an outline of the current status facing glioma. It then provides an overview of the state-of-the-art applications of iron oxide nanoparticles (IONPs) to glioma diagnostics and therapeutics, including MR contrast enhancement, drug delivery, cell labeling and tracking, magnetic hyperthermia treatment and magnetic particle imaging. It also addresses current challenges associated with the biological barriers and IONP design with an emphasis on recent advances and innovative approaches for glioma targeting strategies. Opportunities for future development are highlighted.

Core-shell-corona doxorubicin-loaded superparamagnetic Fe3O4 nanoparticles for cancer theranostics

Superparamagnetic iron oxide magnetic nanoparticles (MNPs) are successfully used as contrast agents in magnetic-resonance imaging. They can be easily functionalized for drug delivery functions, demonstrating great potential for both imaging and therapeutic applications. Here we developed new pH-responsive theranostic core-shell-corona nanoparticles consisting of superparamagentic Fe3O4 core that displays high T2 relaxivity, bovine serum albumin (BSA) shell that binds anticancer drug, doxorubicin (Dox) and poly(ethylene glycol) (PEG) corona that increases stability and biocompatibility. The nanoparticles were produced by adsorption of the BSA shell onto the Fe3O4 core followed by crosslinking of the protein layer and subsequent grafting of the PEG corona using monoamino-terminated PEG via carbodiimide chemistry. The hydrodynamic diameter, zeta-potential, composition and T2 relaxivity of the resulting nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, thermogravimetric analysis and T2-relaxometry. Nanoparticles were shown to absorb Dox molecules, possibly through a combination of electrostatic and hydrophobic interactions. The loading capacity (LC) of the nanoparticles was 8 wt.%. The Dox loaded nanoparticles release the drug at a higher rate at pH 5.5 compared to pH 7.4 and display similar cytotoxicity against C6 and HEK293 cells as the free Dox.

Bionanotechnology and the future of glioma

Designer nanoscaled materials have the potential to revolutionize diagnosis and treatment for glioma. This review summarizes current progress in nanoparticle-based therapies for glioma treatment including targeting, drug delivery, gene delivery, and direct tumor ablation. Preclinical and current human clinical trials are discussed. Although progress in the field has been significant over the past decade, many successful strategies demonstrated in the laboratory have yet to be implemented in human clinical trials. Looking forward, we provide examples of combined treatment strategies, which harness the potential for nanoparticles to interact with their biochemical environment, and simultaneously with externally applied photons or magnetic fields. We present our notion of the "ideal" nanoparticle for glioma, a concept that may soon be realized.