Maxim A. Abakumov

VEGF-targeted magnetic nanoparticles for MRI visualization of brain tumor.

UNLABELLED This work is focused on synthesis and characterization of targeted magnetic nanoparticles as magnetic resonance imaging (МRI) agents for in vivo visualization of gliomas. Ferric oxide (Fe3O4) cores were synthesized by thermal decomposition and coated with bovine serum albumin (BSA) to form nanoparticles with Deff of 53±9nm. The BSA was further cross-linked to improve colloidal stability. Monoclonal antibodies against vascular endothelial growth factor (mAbVEGF) were covalently conjugated to BSA through a polyethyleneglycol linker. Here we demonstrate that 1) BSA coated nanoparticles are stable and non-toxic to different cells at concentration up to 2.5mg/mL; 2) conjugation of monoclonal antibodies to nanoparticles promotes their binding to VEGF-positive glioma С6 cells in vitro; 3) targeted nanoparticles are effective in MRI visualization of the intracranial glioma. Thus, mAbVEGF-targeted BSA-coated magnetic nanoparticles are promising MRI contrast agents for glioma visualization. FROM THE CLINICAL EDITOR This work focuses on synthesis and characterization of targeted magnetic nanoparticles as magnetic resonance imaging (МRI) agents for in vivo visualization of gliomas. The authors utilize the fact that high-grade gliomas have extensive areas of necrosis and hypoxia, which results in increased secretion of angiogenesis vascular endothelial growth factor (VEGF). Monoclonal antibodies against vascular endothelial growth factor (mAbVEGF) were covalently conjugated to crosslinked BSA coated ferric oxide (Fe3O4) nanoparticles. The results show that these targeted nanoparticles are effective in MRI visualization of the intracranial glioma and may provide a new and promising contrast agent.

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.

Targeted Delivery of Cisplatin by Сonnexin 43 Vector Nanogels to the Focus of Experimental Glioma C6

The aim of this study was to create a nanocontainer conjugated with monoclonal antibodies to connexin 43 (Cx43) that is actively expressed at the periphery of C6 glioma and in the astroglia roll zone. Stable vector nanogels with high (up to 35%) cisplatin load were synthesized. The antitumor effects of Cx43-modified cisplatin-loaded nanogels, free cisplatin, and nonspecific drugs were carried out on C6 glioma model. Vector nanogels reduced systemic toxicity of cisplatin, effectively inhibited tumor growth, and significantly prolonged the lifespan of animals with experimental tumors.

Site-Directed Delivery of VEGF-Targeted Liposomes into Intracranial C6 Glioma

The efficiency of conventional chemotherapy for aggressive tumors in the CNS remains low and new strategies for the targeted delivery of anti-tumor substances are now actively developed. Pegylated liposomes covalently conjugated with monoclonal antibodies to VEGF synthesized by us are nanoparticle characterized by narrow size distribution and high dispersion stability. Immunochemical activity of antibodies after conjugation was 70% of initial level. The anti-VEGF liposomes developed by us were highly specific for VEGF+ tumor cells (in vitro and in vivo). Intravenous injection of VEGF-liposomes to rats with intracranial C6 glioma was followed by their specific accumulation in the malignant tissues and engulfment by glioma cells, which attested to target delivery and selective accumulation of anti-VEGF-liposomes in the brain tumor. Thus, the use of targeting molecules can significantly increase the distribution and efficiency of delivery of nanocontainers to a tumor characterized by hyperexpression of the target proteins.

Multimodal doxorubicin loaded magnetic nanoparticles for VEGF targeted theranostics of breast cancer

In presented paper we have developed new system for cancer theranostics based on vascular endothelial growth factor (VEGF) targeted magnetic nanoparticles. Conjugation of anti-VEGF antibodies with bovine serum albumin coated PEGylated magnetic nanoparticles allows for improved binding with murine breast adenocarcinoma 4T1 cell line and facilitates doxorubicin delivery to tumor cells. It was shown that intravenous injection of doxorubicin loaded VEGF targeted nanoparticles increases median survival rate of mice bearing 4T1 tumors up to 50%. On the other hand magnetic resonance imaging (MRI) of 4T1 tumors 24 h after intravenous injection showed accumulation of nanoparticles in tumors, thus allowing simultaneous cancer therapy and diagnostics.

Synthesis of Iron Oxide Nanoclusters by Thermal Decomposition

Herein, we report a novel one-step solvothermal synthesis of magnetite nanoclusters (MNCs). In this report, we discuss the synthesis, structure, and properties of MNCs and contrast enhancement in T2-weighted MR images using magnetite nanoclusters. The effect of different organic acids, used as surfactants, on the size and shape of MNCs was investigated. The structure and properties of samples were determined by magnetic measurements, TGA, TEM, HRTEM, XRD, FTIR, and MRI. Magnetic measurements show that obtained MNCs have relatively high saturation magnetization values (65.1-81.5 emu/g) and dependence of the coercive force on the average size of MNCs was established. MNCs were transferred into an aqueous medium by Pluronic F-127, and T2-relaxivity values were determined. T2-Weighted MR phantom images clearly demonstrated that such magnetite nanoclusters can be used as contrast agents for MRI.

Multilayer polyion complex nanoformulations of superoxide dismutase 1 for acute spinal cord injury

Abstract As one of the most devastating forms of trauma, spinal cord injury (SCI) remains a challenging clinical problem. The secondary processes associated with the primary injury, such as overproduction of reactive oxygen species (ROS) and inflammation, lead to concomitant compression of the injured spinal cord and neuronal death. Delivery of copper‐zinc superoxide dismutase (SOD1), an efficient ROS scavenger, to the site of injury can mitigate SCI‐induced oxidative stress and tissue damage. Towards this goal catalytically active nanoformulations of SOD1 (“nanozymes”) are developed as a modality for treatment of SCI. Along with the cross‐linked polyion complex of SOD1 with polycation poly(ethylene glycol) (PEG)‐polylysine (single‐coat (SC) nanozyme), we introduce for the first time the chemically cross‐linked multilayer polyion complex in which SOD1 is first incorporated into a polyion complex with polycation, then coated by anionic block copolymer, PEG‐polyglutamic acid (double‐coat (DC) nanozyme). We developed DC nanozymes with high enzymatic activity and ability to retain and protect SOD1 under physiological conditions. Pharmacokinetic study revealed that DC nanozymes significantly prolonged circulation of active SOD1 in the blood stream compared to free SOD1 or SC nanozymes (half‐life was 60 vs 6 min). Single intravenous injection of DC nanozymes (5 kU of SOD1/kg) improved the recovery of locomotor functions in rats with moderate SCI, along with reduction of swelling, concomitant compression of the spinal cord and formation of post‐traumatic cysts. Thus, based on the testing in a rodent model the SOD1 DC nanozymes are promising modality for scavenging ROS, decreasing inflammation and edema, and improving recovery after SCI. Graphical abstract Figure. No Caption available.

Synthesis and Investigation of Photophysical and Biological Properties of Novel S-Containing Bacteriopurpurinimides

Novel hybrid molecule containing 2-mercaptoethylamine was synthesized starting from O-propyloxime-N-propoxy bacteriopurpurinimide (dipropoxy-BPI), which was readily oxidized in oxygen atmosphere yielding the corresponding disulfide analogue (disulfide-BPI). Spectral, photophysical, photodynamic, and biological properties of compound were properly evaluated. Compounds bearing disulfide moiety can directly interact with glutathione (GSH), thereby reducing its intracellular concentration. Indeed, mice sarcoma S37 cell line was treated in vitro with disulfide-BPI, yielding a CC50 value of 0.05 ± 0.005 μM. A relatively high level of singlet oxygen was detected. It was demonstrated (by fluorescence) that the PS was rapidly accumulated in a cancer nest (S37) at a relatively high level after 2 h upon intravenous administration. After 24 h, no traces of the molecule were detected in the tumor mass. Moreover, high photodynamic efficiency was demonstrated at doses of 150-300 J/cm2 against two different in vivo tumor models, achieving 100% regression of cancer growth.

Synthesis and characterization of PEG-silane functionalized iron oxide(II, III) nanoparticles for biomedical application

In this paper we report the synthesis, functionalization, and characterization of ferromagnetic iron oxide (II, III) nanoparticles with different shapes and sizes. Using a number of chemical methods, magnetite nanoparticles having a spherical shape and size of 9 ± 2 nm (coprecipitation), 22 ± 4 nm and 50 ± 6 nm (redox reaction), and 40 ± 5 nm cubes were synthesized. Special attention in this paper is devoted to the covalent modification of magnetite nanoparticles by polymers such as silane-polyethylene glycol (Peg-silane). The main advantage of magnetic nanoparticles modified by polymer is low toxicity, colloidal stability of the prepared magnetite nanoparticles, and the possibility for post functionalization. We determined coercivity and saturated magnetism. Also, the relaxivity T2 was measured by magnetic resonance imaging (MRI). Prepared nanoparticles are of great interest and potential for use in biomedical imaging.

New experimental model of brain tumors in brains of adult immunocompetent rats.

Aims: Xenograft models, namely heterotransplantation of human cancer cells or tumor biopsies into immunodeficient rodents are the major preclinical approach for the development of novel cancer therapeutics. However, in these models the animals must be used only after the severe systemic immune suppression in order to ensure graft survival. Thus, additional new human brain tumor models without immune suppression of the recipient rodent may be required. Place and Duration of Study: Laboratory of Immunochemistry, V.P. Serbsky National Research Centre for Social and Forensic Psychiatry and Department of Nanobiotechnology, N.I. Pirogov Russian State Medical University and Department of Biosynthesis of Nucleic Acids, Institute of Molecular Biology and Genetics between June 2009 and July 2010. Methodology: Brain tumor modeling was performed by intracerebral stereotactic implantation of cells to the healthy adult rats without any artificial immunodepression. Cells were implanted to the striatum region of ketamine-anesthetized rats at specific coordinates according to Swansons rat brain atlas. Tumor growth was monitored Research Article British Journal of Medicine & Medical Research, 2(2): 206-215, 2012 207 weekly via registration of neurological signs and in vivo Bruker MRI system. Results: On the 21st day after implantation of C6 glioma, U251 or 293_CHI3L1 cells severe neurological deficit appeared in rats. Huge intracerebral tumors were found in each animal under investigation while no tumor growth was observed for at least 8 weeks in rats injected with empty vector-transfected 293 cells. Tumors contained the dense superficial cell layer and prominent lobules with central newly ingrowing blood vessels. Histological assay revealed displacement of median cerebral structures and hydrocephalus in contralateral hemisphere. All tumors were surrounded by numerous GFAP-positive reactive astrocytes. Conclusion: Positive results with transplantation of 293_CHI3L1 cells into adult rat brains without any immunosupression show the validity of this animal model. In all experiments such implantations provoked malignant tumor formation while there were no visible tumors in control rats. We believe this to be the first animal model of human brain tumor that displays the possibility to study various biologic features of and host therapeutic response to brain tumor in an immunocompetent host.