Dimercaptosuccinic acid-coated magnetite nanoparticles for magnetically guided in vivo delivery of interferon gamma for cancer immunotherapy

Superparamagnetic iron oxide nanoparticle-based delivery systems for biotherapeutics

INTRODUCTION

Superparamagnetic iron oxide nanoparticle (SPION)-based carrier systems have many advantages over other nanoparticle-based systems. They are biocompatible, biodegradable, facilely tunable and superparamagnetic and thus controllable by an external magnetic field. These attributes enable their broad biomedical applications. In particular, magnetically driven carriers are drawing considerable interest as an emerging therapeutic delivery system because of their superior delivery efficiency.

AREAS COVERED

This article reviews the recent advances in use of SPION-based carrier systems to improve the delivery efficiency and target specificity of biotherapeutics. The authors examine various formulations of SPION-based delivery systems, including SPION micelles, clusters, hydrogels, liposomes and micro/nanospheres, as well as their specific applications in delivery of biotherapeutics.

EXPERT OPINION

Recently, biotherapeutics including therapeutic cells, proteins and genes have been studied as alternative treatments to various diseases. Despite the advantages of high target specificity and low adverse effects, clinical translation of biotherapeutics has been hindered by the poor stability and low delivery efficiency compared with chemical drugs. Accordingly, biotherapeutic delivery systems that can overcome these limitations are actively pursued. SPION-based materials can be ideal candidates for developing such delivery systems because of their excellent biocompatibility and superparamagnetism that enables long-term accumulation/retention at target sites by utilization of a suitable magnet. In addition, synthesis technologies for production of finely tuned, homogeneous SPIONs have been well developed, which may promise their rapid clinical translation.

A novel magnetic nanoparticle drug carrier for enhanced cancer chemotherapy

BACKGROUND

Magnetic nanoparticles (NPs) loaded with antitumor drugs in combination with an external magnetic field (EMF)-guided delivery can improve the efficacy of treatment and may decrease serious side effects. The purpose of this study was 1) to investigate application of PEG modified GMNPs (PGMNPs) as a drug carrier of the chemotherapy compound doxorubicin (DOX) in vitro; 2) to evaluate the therapeutic efficiency of DOX-conjugated PGMNPs (DOX-PGMNPs) using an EMF-guided delivery in vivo.

METHODS

First, DOX-PGMNPs were synthesized and the cytotoxicity of DOX-PGMNPs was assessed in vitro. Second, upon intravenous administration of DOX-PMGPNs to H22 hepatoma cell tumor-bearing mice, the DOX biodistribution in different organs (tissues) was measured. The antitumor activity was evaluated using different treatment strategies such as DOX-PMGPNs or DOX-PMGPNs with an EMF-guided delivery (DOX-PGMNPs-M).

RESULTS

The relative tumor volumes in DOX-PGMNPs-M, DOX-PGMNPs, and DOX groups were 5.46±1.48, 9.22±1.51, and 14.8±1.64, respectively (each p<0.05), following treatment for 33 days. The life span of tumor-bearing mice treated with DOX-PGMNPs-M, DOX-PGMNPs, and DOX were 74.8±9.95, 66.1±13.5, and 31.3±3.31 days, respectively (each p<0.05).

CONCLUSION

This simple and adaptive nanoparticle design may accommodate chemotherapy for drug delivery optimization and in vivo drug-target definition in system biology profiling, increasing the margin of safety in treatment of cancers in the near future.

Selective targeting of interferon γ to stromal fibroblasts and pericytes as a novel therapeutic approach to inhibit angiogenesis and tumor growth

New approaches to block the function of tumor stromal cells such as cancer-associated fibroblasts and pericytes is an emerging field in cancer therapeutics as these cells play a crucial role in promoting angiogenesis and tumor growth via paracrine signals. Because of immunomodulatory and other antitumor activities, IFNγ, a pleiotropic cytokine, has been used as an anticancer agent in clinical trials. Unfortunately only modest beneficial effects, but severe side effects, were seen. In this study, we delivered IFNγ to stromal fibroblasts and pericytes, considering its direct antifibrotic activity, using our platelet-derived growth factor-beta receptor (PDGFβR)-binding carrier (pPB-HSA), as these cells abundantly express PDGFβR. We chemically conjugated IFNγ to pPB-HSA using a heterobifunctional PEG linker. In vitro in NIH3T3 fibroblasts, pPB-HSA-IFNγ conjugate activated IFNγ-signaling (pSTAT1α) and inhibited their activation and migration. Furthermore, pPB-HSA-IFNγ inhibited fibroblasts-induced tube formation of H5V endothelial cells. In vivo in B16 tumor-bearing mice, pPB-HSA-IFNγ rapidly accumulated in tumor stroma and pericytes and significantly inhibited the tumor growth while untargeted IFNγ and pPB-HSA carrier were ineffective. These antitumor effects of pPB-HSA-IFNγ were attributed to the inhibition of tumor vascularization, as shown with α-SMA and CD-31 staining. Moreover, pPB-HSA-IFNγ induced MHC-II expression specifically in tumors compared with untargeted IFNγ, indicating the specificity of this approach. This study thus shows the impact of drug targeting to tumor stromal cells in cancer therapy as well as provides new opportunities to use cytokines for therapeutic application.

Biological applications of magnetic nanoparticles

In this review an overview about biological applications of magnetic colloidal nanoparticles will be given, which comprises their synthesis, characterization, and in vitro and in vivo applications. The potential future role of magnetic nanoparticles compared to other functional nanoparticles will be discussed by highlighting the possibility of integration with other nanostructures and with existing biotechnology as well as by pointing out the specific properties of magnetic colloids. Current limitations in the fabrication process and issues related with the outcome of the particles in the body will be also pointed out in order to address the remaining challenges for an extended application of magnetic nanoparticles in medicine.

Pluronic@Fe3O4 nanoparticles with robust incorporation of doxorubicin by thermo-responsiveness

Doxorubicin was physically incorporated in magnetic nanoparticles by thermo-responsive manners. Magnetic nanoparticles were prepared by oxidizing ferric ions in ammonium solution. Thiolated Pluronic was synthesized by sequential modification of terminal hydroxyl groups of Pluronic to amine groups and thiol groups. Magnetic nanoparticles composed of iron oxide were surface-modified with thiolated Pluronic at different molar ratios of iron to thiol groups. Pluronic decoration on the magnetic nanoparticles was characterized by elemental analysis and transmission electron microscopy. Elemental analysis results on carbon atoms in the magnetic nanoparticles showed that the degree of Pluronic decoration was proportional to the feed ratio of thiolated Pluronic to iron oxide. Doxorubicin was incorporated to the magnetic nanoparticles thermo-responsive manners; a mixture of hydrophobized doxorubicin and the magnetic nanoparticles was incubated at 4°C and the temperature was subsequently increased to 37°C for thermally induced structural changes of the decorated Pluronic moieties. Doxorubicin-incorporated magnetic nanoparticles showed dramatic modulations of size distributions according to temperature changes, which was dependent on the degree of Pluronic decoration. Loading efficiency of doxorubicin was significantly affected by the number of decorated Pluronic on the magnetic nanoparticles; the higher Pluronic moieties the nanoparticles had, the higher loading efficiency they showed. Release profiles of doxorubicin from the nanoparticles showed that doxorubicin was liberated from the nanoparticles in response to reducing conditions of the release medium. Anti-cancer activities of the doxorubicin-incorporated nanoparticles were determined by a MTT-based cytotoxicity assay against A549 cell lines. Compared to native doxorubicin, the doxorubicin incorporated magnetites showed attenuated cytotoxicities due to slow release of doxorubicin from the carriers. Thus, thermally induced incorporation of anti-cancer drugs can be a novel method for multifunctional magnetic nanoparticles with imaging and anti-cancer treatments.

Magnetic Nanoparticles Embedded in a Silicon Matrix

This paper represents a short overview of nanocomposites consisting of magnetic nanoparticles incorporated into the pores of a porous silicon matrix by two different methods. On the one hand, nickel is electrochemically deposited whereas the nanoparticles are precipitated on the pore walls. The size of these particles is between 2 and 6 nm. These particles cover the pore walls and form a tube-like arrangement. On the other hand, rather well monodispersed iron oxide nanoparticles, of 5 and 8 nm respectively, are infiltrated into the pores. From their size the particles would be superparamagnetic if isolated but due to magnetic interactions between them, ordering of magnetic moments occurs below a blocking temperature and thus the composite system displays a ferromagnetic behavior. This transition temperature of the nanocomposite can be varied by changing the filling factor of the particles within the pores. Thus samples with magnetic properties which are variable in a broad range can be achieved, which renders this composite system interesting not only for basic research but also for applications, especially because of the silicon base material which makes it possible for today's process technology.