Magnetometry based method for investigation of nanoparticle clearance from circulation in a liver perfusion model

Optimization of Size of Nanosensitizers for Antitumor Radiotherapy Using Mathematical Modeling

The efficacy of antitumor radiotherapy can be enhanced by utilizing nonradioactive nanoparticles that emit secondary radiation when activated by a primary beam. They consist of small volumes of a radiosensitizing substance embedded within a polymer layer, which is coated with tumor-specific antibodies. The efficiency of nanosensitizers relies on their successful delivery to the tumor, which depends on their size. Increasing their size leads to a higher concentration of active substance; however, it hinders the penetration of nanosensitizers through tumor capillaries, slows down their movement through the tissue, and accelerates their clearance. In this study, we present a mathematical model of tumor growth and radiotherapy with the use of intravenously administered tumor-specific nanosensitizers. Our findings indicate that their optimal size for achieving maximum tumor radiosensitization following a single injection of their fixed total volume depends on the permeability of the tumor capillaries. Considering physiologically plausible spectra of capillary pore radii, with a nanoparticle polymer layer width of 7 nm, the optimal radius of nanoparticles falls within the range of 13-17 nm. The upper value is attained when considering an extreme spectrum of capillary pores.

Influence of magnetic nanoparticle biotransformation on contrasting efficiency and iron metabolism

Magnetic nanoparticles are widely used in biomedicine for MRI imaging and anemia treatment. The aging of these nanomaterials in vivo may lead to gradual diminishing of their contrast properties and inducing toxicity. Here, we describe observation of the full lifecycle of 40-nm magnetic particles from their injection to the complete degradation in vivo and associated impact on the organism. We found that in 2 h the nanoparticles were eliminated from the bloodstream, but their initial biodistribution changed over time. In 1 week, a major part of the nanoparticles was transferred to the liver and spleen, where they degraded with a half-life of 21 days. MRI and a magnetic spectral approach revealed preservation of contrast in these organs for more than 1 month. The particle degradation led to the increased number of red blood cells and blood hemoglobin level due to released iron without causing any toxicity in tissues. We also observed an increase in gene expression level of Fe-associated proteins such as transferrin, DMT1, and ferroportin in the liver in response to the iron particle degradation. A deeper understanding of the organism response to the particle degradation can bring new directions to the field of MRI contrast agent design.

Pharmacokinetics of magnetic iron oxide nanoparticles for medical applications

Magnetic iron oxide nanoparticles (MNPs) have been under intense investigation for at least the last five decades as they show enormous potential for many biomedical applications, such as biomolecule separation, MRI imaging and hyperthermia. Moreover, a large area of research on these nanostructures is concerned with their use as carriers of drugs, nucleic acids, peptides and other biologically active compounds, often leading to the development of targeted therapies. The uniqueness of MNPs is due to their nanometric size and unique magnetic properties. In addition, iron ions, which, along with oxygen, are a part of the MNPs, belong to the trace elements in the body. Therefore, after digesting MNPs in lysosomes, iron ions are incorporated into the natural circulation of this element in the body, which reduces the risk of excessive storage of nanoparticles. Still, one of the key issues for the therapeutic applications of magnetic nanoparticles is their pharmacokinetics which is reflected in the circulation time of MNPs in the bloodstream. These characteristics depend on many factors, such as the size and charge of MNPs, the nature of the polymers and any molecules attached to their surface, and other. Since the pharmacokinetics depends on the resultant of the physicochemical properties of nanoparticles, research should be carried out individually for all the nanostructures designed. Almost every year there are new reports on the results of studies on the pharmacokinetics of specific magnetic nanoparticles, thus it is very important to follow the achievements on this matter. This paper reviews the latest findings in this field. The mechanism of action of the mononuclear phagocytic system and the half-lives of a wide range of nanostructures are presented. Moreover, factors affecting clearance such as hydrodynamic and core size, core morphology and coatings molecules, surface charge and technical aspects have been described.

Systematic Review of Cancer Targeting by Nanoparticles Revealed a Global Association between Accumulation in Tumors and Spleen

Active targeting of nanoparticles toward tumors is one of the most rapidly developing topics in nanomedicine. Typically, this strategy involves the addition of cancer-targeting biomolecules to nanoparticles, and studies on this topic have mainly focused on the localization of such formulations in tumors. Here, the analysis of the factors determining efficient nanoparticle targeting and therapy, various parameters such as types of targeting molecules, nanoparticle type, size, zeta potential, dose, and the circulation time are given. In addition, the important aspects such as how active targeting of nanoparticles alters biodistribution and how non-specific organ uptake influences tumor accumulation of the targeted nanoformulations are discussed. The analysis reveals that an increase in tumor accumulation of targeted nanoparticles is accompanied by a decrease in their uptake by the spleen. There is no association between targeting-induced changes of nanoparticle concentrations in tumors and other organs. The correlation between uptake in tumors and depletion in the spleen is significant for mice with intact immune systems in contrast to nude mice. Noticeably, modulation of splenic and tumor accumulation depends on the targeting molecules and nanoparticle type. The median survival increases with the targeting-induced nanoparticle accumulation in tumors; moreover, combinatorial targeting of nanoparticle drugs demonstrates higher treatment efficiencies. Results of the comprehensive analysis show optimal strategies to enhance the efficiency of actively targeted nanoparticle-based medicines.

In vivo blockade of mononuclear phagocyte system with solid nanoparticles: Efficiency and affecting factors

Smart nanomaterials, contrast nanoparticles and drug nanocarriers of advanced targeting architecture were designed for various biomedical applications. Most of such agents demonstrate poor pharmacokinetics in vivo due to rapid elimination from the bloodstream by cells of the mononuclear phagocyte system (MPS). One of the promising methods to prolong blood circulation of the nanoparticles without their modification is MPS blockade. The method temporarily decreases macrophage endocytosis in response to uptake of a low-toxic non-functional material. The effect of different factors on the efficiency of macrophage blockade in vivo induced by solid nanomaterials has been studied here. Those include: blocker nanoparticle size, ζ-potential, surface coating, dose, mice strain, presence of tumor or inflammation. We found that the blocker particle coating type had the strongest effect on MPS blockade efficiency, which allowed to prolong functional particle blood circulation half-life 18 times. The mechanisms capable of regulation of the MPS blockade have been demonstrated, which can promote application of this phenomenon in medicine for improving delivery of diagnostic and therapeutic nanomaterials.

Fast processes of nanoparticle blood clearance: Comprehensive study

Blood circulation is the key parameter that determines the in vivo efficiency of nanoagents. Despite clinical success of the stealth liposomal agents with their inert and shielded surfaces, a great number of non-stealth nanomaterials is being developed due to their potential of enhanced functionality. By harnessing surface phenomena, such agents can offer advanced control over drug release through intricately designed nanopores, catalysis-propelled motion, computer-like analysis of several disease markers for precise target identification, etc. However, investigation of pharmacokinetic behavior of these agents becomes a great challenge due to ultra-short circulation (usually around several minutes) and impossibility to use the invasive blood-sampling techniques. Accordingly, the data on circulation of such agents has been scarce and irregular. Here, we demonstrate high-throughput capabilities of the developed magnetic particle quantification technique for nanoparticle circulation measurements and present a comprehensive investigation of factors that affect blood circulation of the non-stealth nanoparticles. Namely, we studied the following 9 factors: particle size, zeta-potential, coating, injection dose, repetitive administration, induction of anesthesia, mice strain, absence/presence of tumors, tumor size. Our fundamental findings demonstrate potential ways to extend the half-life of the agents in blood thereby giving them a better chance of achieving their goal in the organism. The study will be valuable for design of the next generation nanomaterials with advanced biomedical functionality.

Antibody-directed metal-organic framework nanoparticles for targeted drug delivery

Nanosized metal-organic frameworks (nMOFs) have shown great promise as high-capacity carriers for a variety of applications. For biomedicine, numerous nMOFs have been proposed that can transport virtually any molecular drug, can finely tune their payload release profile, etc. However, perspectives of their applications for the targeted drug delivery remain relatively unclear. So far, only a few works have reported specific cell targeting by nMOFs exclusively through small ligands such as folic acid or RGD peptides. Here we show feasibility of targeted drug delivery to specific cancer cells in vitro with nMOFs functionalized with such universal tool as an antibody. We demonstrate ca. 120 nm magnetic core/MOFs shell nanoagents loaded with doxorubicin/daunorubicin and coupled with an antibody though a hydrophilic carbohydrate interface. We show that carboxymethyl-dextran coating of nMOFs allows extensive loading of the drug molecules (up to 15.7 mg/g), offers their sustained release in physiological media and preserves antibody specificity. Reliable performance of the agents is illustrated with trastuzumab-guided selective targeting and killing of HER2/neu-positive breast cancer cells in vitro. The approach expands the scope of nMOF applications and can serve as a platform for the development of potent theranostic nanoagents. STATEMENT OF SIGNIFICANCE: The unique combination of exceptional drug capacity and controlled release, biodegradability and low toxicity makes nanosized metal-organic frameworks (nMOFs) nearly ideal drug vehicles for various biomedical applications. Unfortunately, the prospective of nMOF applications for the targeted drug delivery is still unclear since only a few examples have been reported for nMOF cell targeting, exclusively for small ligands. In this work, we fill the important gap and demonstrate nanoagent that can specifically kill target cancer cells via drug delivery based on recognition of HER2/neu cell surface receptors by such universal and specific tool as antibodies. The proposed approach is universal and can be adapted for specific biomedical tasks using antibodies of any specificity and nMOFs of a various composition.

A simplified 3D liver microsphere tissue culture model for hepatic cell signaling and drug-induced hepatotoxicity studies

Although a number of experimental models have been developed for liver research, each has its own advantages and disadvantages. The present study attempted to develop a simple and effective 3‑dimensional mouse liver microsphere tissue culture (LMTC) model in vitro for the analysis of hepatic functions. Hepatic characteristics and potential applications of this model were compared with that of mouse model in vivo and mouse primary hepatocytes in vitro. Using freshly‑perfused mouse liver tissue passed through 80‑mesh sift strainer (sift80), it was demonstrated that under the optimal culture conditions, the sift80 microsphere tissue cultured in 2% bovine calf serum medium remained viable with marked proliferating cell nuclear antigen and anti‑Myc proto‑oncogene protein expression, exhibited normal hepatic functions including indocyanine green (ICG) uptake/release and periodic acid‑Schiff staining, and expressed hepatocyte‑specific genes for up to 2 weeks. The microsphere tissue was responsive to bone morphogenic protein 9 (BMP9) stimulation leading to upregulation of downstream targets of BMP9 signaling. Furthermore, 3 commonly‑used liver‑damaging drugs were indicated to effectively inhibit hepatic ICG uptake, and induce the expression of hepatotoxicity‑associated genes. Therefore, this simplified LMTC model may be a useful in vitro tissue culture model to investigate drug‑induced liver injury and metabolism, and hepatocyte‑based cell singling.