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Soenen S.J.,Ghent University | De Cuyper M.,Laboratory of BioNanoColloids | De Smedt S.C.,Ghent University | Braeckmans K.,Ghent University
Methods in Enzymology | Year: 2012

The use of iron oxide nanoparticles (IONPs) in biomedical research is steadily increasing, leading to the rapid development of novel IONP types and an increased exposure of cultured cells to a wide variety of IONPs. Due to the large variation in incubation conditions, IONP characteristics, and cell types studied, it is still unclear whether IONPs are generally safe or should be used with caution. During the past years, several contradictory observations have been reported, which highlight the great need for a more thorough understanding of cell-IONP interactions. To improve our knowledge in this field, there is a great need for standardized protocols and toxicity assays, that would allow to directly compare the cytotoxic potential of any IONP type with previously screened particles. Here, several approaches are described that allow to rapidly but thoroughly address several parameters which are of great impact for IONP-induced toxicity. These assays focus on acute cytotoxicity, induction of reactive oxygen species, measuring the amount of cell-associated iron, assessing cell morphology, cell proliferation, cell functionality, and possible pH-induced or intracellular IONP degradation. Together, these assays may form the basis for any detailed study on IONP cytotoxicity. © 2012 Elsevier Inc. All rights reserved.

Soenen S.J.,Laboratory of BioNanoColloids | Soenen S.J.,Ghent University | De Cuyper M.,Laboratory of BioNanoColloids
Contrast Media and Molecular Imaging | Year: 2011

The range of different types of nanoparticles and their biomedical applications is rapidly growing, creating a need to thoroughly examine the effects these particles have on biological entities. One of the most commonly used nanoparticle types is iron oxide nanoparticles, which can be used as MRI contrast agents. The main research topic is the in vitro labeling of cells with iron oxide nanoparticles to render the cells detectable for MRI upon in vivo transplantation. For the correct evaluation of cell function and behavior in vivo, any effects of the nanoparticles on the cells must be completely ruled out. The present work provides a technical note where a detailed overview is given of several assays that could be useful to determine nanoparticle toxicity. The assays described focus on (i) nanoparticle internalization, (ii) immediate cell toxicity, (iii) cell proliferation, (iv) cell morphology, (v) cell functionality and (vi) cell physiology. Potential pitfalls, appropriate controls and advantages/disadvantages of the different assays are given. The main focus of this work is to provide a detailed guide to help other researchers in the field interested in setting up nanoparticle-toxicity studies. © 2010 John Wiley & Sons, Ltd.

Soenen S.J.,Laboratory of BioNanoColloids | De Meyer S.F.,Laboratory for Thrombosis Research | Dresselaers T.,Biomedical NMR Unit MoSAIC | Velde G.V.,Biomedical NMR Unit MoSAIC | And 5 more authors.
Biomaterials | Year: 2011

The use of contrast material to stimulate magnetic resonance imaging (MRI) of migrating cells has become an important area of research. In the present study, cationic magnetoliposomes (MLs) were used to magnetically label human blood outgrowth endothelial cells (BOECs) and follow their homing by magnetic resonance imaging (MRI). The biodistribution and functional integration capacity of BOECs, which have shown extensive promise as gene delivery vehicles, have thus far only rarely been investigated. MLs were avidly internalized by BOECs giving clear MRI contrast in phantom studies and the magnetic labeling did not affect cell proliferation, viability, morphology or homeostasis and elicited only minor reactive oxygen species levels. Intravenous injection of labeled BOECs was compared with injection of free MLs and unlabeled BOECs, resulting in homing of BOECs toward the liver and spleen, which was confirmed by histology. The MLs used offer great potential for cellular tracking studies by MRI when low levels of widely distributed cells are present. In particular, the use of these MLs will allow to evaluate the efficacy of new methods to enhance BOEC homing and integration to optimize their use as efficient vehicles for gene therapy. © 2011 Elsevier Ltd.

Soenen S.J.,Laboratory of BioNanoColloids | Velde G.V.,University Medical Hospital Gasthuisberg | Ketkar-Atre A.,University Medical Hospital Gasthuisberg | Himmelreich U.,University Medical Hospital Gasthuisberg | De Cuyper M.,Laboratory of BioNanoColloids
Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology | Year: 2011

Among the wide variety in iron oxide nanoparticles which are routinely used as magnetic resonance imaging (MRI) contrast agents, magnetoliposomes (MLs) take up a special place. In the present work, the two main types (large and small MLs) are defined and their specific features are commented. For both types of MLs, the flexibility of the lipid coating allows for efficient functionalization, enabling bimodal imaging (e.g., MRI and fluorescence) or the use of MLs as theranostics. These features are especially true for large MLs, where several magnetite cores are encapsulated within a single large liposome, which were found to be highly efficient theranostic agents. By carefully fine-tuning the number of magnetite cores and attaching Gd3+-complexes onto the liposomal surface, the large MLs can be efficiently optimized for dynamic MRI. A special type of MLs, biogenic MLs, can also be efficiently used in this regard, with potential applications in cancer treatment and imaging. Small MLs, where the lipid bilayer is immediately attached onto a solid magnetite core, give a very high r2/r1 ratio. The flexibility of the lipid bilayer allows the incorporation of poly(ethylene glycol)-lipid conjugates to increase blood circulation times and be used as bone marrow contrast agents. Cationic lipids can also be incorporated, leading to high cell uptake and associated strong contrast generation in MRI of implanted cells. Unique for these small MLs is the high resistance the particles exhibit against intracellular degradation compared with dextran- or citrate-coated particles. Additionally, intracellular clustering of the iron oxide cores enhances negative contrast generation and enables longer tracking of labeled cells in time. Copyright © 2011 John Wiley & Sons, Inc.

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