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NEUROPHARMACOLOGY
University Institute of Pathology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (F.C., L.J.-J.); Department of Pharmacology, McGill University, Montreal, Canada (D.M.); Institute of Physiology, University of Lausanne, Lausanne, Switzerland (F.T.-M.); Department of Cell Physiology and Metabolism and Medical Radiology, University of Geneva, Geneva, Switzerland (X.M.); Guerbet Research, Roissy, France (C.C.); and Institute of Materials Science, Laboratory of Powder Technology, Swiss Federal Institute of Technology (Ecole Polytechnique Fédérale de Lausanne), Lausanne, Switzerland (A.P.-F., H.H.)
Received January 26, 2006; accepted April 10, 2006.
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Abstract |
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; Savic et al., 2003) of drugs may be controlled and improved by their entrapment in colloidal nanomaterials, mainly of the micellar structure, such as nanocontainers. The development of a large variety of colloidal dispersions of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) has added a supplementary function to nanomaterials, their magnetic properties, which can lead to a range of new biological, biomedical, and diagnostic applications. In particular, the application of the different forms of iron oxides for radiological diagnostic procedures to document vascular leakage, macrophage imaging, or cell tracking (Weissleder et al., 1997; Ruehm et al., 2001; Brigger et al., 2002; Hoehn et al., 2002; Kircher et al., 2003; Corot et al., 2004; Neuwelt et al., 2004; Raynal et al., 2004; Sundstrom et al., 2004; Triverdi et al., 2004; Daldrup-Link et al., 2005), is gaining wide acceptance in radiological practice, but these agents are only very poorly taken up by cells, depending on their size or the expression of the scavenger receptors by cells (Ruehm et al., 2001; Corot et al., 2004; Raynal et al., 2004; Triverdi et al., 2004).
Therefore, the next challenge will be to develop and define the chemical and biophysical characteristics of biocompatible SPIONs that are able to intracellularly deliver therapeutic drugs, in particular in neurodegenerative diseases without inducing deleterious cell reaction, coupled to the detection of active lesions. SPIONs are able, under some conditions, to pass the blood-brain barrier, either by direct transport (Lockman et al., 2003, 2004; Kreuter, 2004; Muller and Keck, 2004) or using an indirect route via the olfactory bulb (Obersdörster et al., 2004; Kandimalla and Donovan, 2005) and to document active lesions by MRI in neurodegenerative disorders (Corot et al., 2004). However, particles that can penetrate into the brain, and other organs, also pose a potential health risk (Colvin, 2003; Borm and Kreyling, 2004; Hoet et al., 2004; Obersdörster et al., 2004). A better understanding of how properties of nanoparticles define their interactions with cells, tissues, and organs in humans and animals is a considerable scientific challenge but one that must be addressed to ascertain the feasibility of using nanobiotechnologies in biomedical applications.
In a preliminary approach, we have prepared and characterized various polyvinyl-alcohol-coated SPIONs (Chastellain et al., 2004; Petri-Fink et al., 2005) that displayed the potential to interact with nonphagocytic human tumor cells. To evaluate their brain biocompatibility and their potential for drug delivery to the brain, we determined the uptake of and inflammatory reaction toward SPIONs of various size and coating characteristics, using either isolated brain cells, i.e., the brain macrophages (microglial cells) and endothelial cells forming the blood-brain barrier, and differentiating aggregated three-dimensional brain cells at different stages of differentiation.
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Materials and Methods |
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; van Ewijk et al., 1999; Chastellain et al., 2004). In brief, SPIONs were prepared by alkaline coprecipitation of ferric (0.086 M) and ferrous (0.043 M) chlorides (Fluka, Buchs, Switzerland). After washing with water, the black precipitate was refluxed in 0.8 M nitric oxide-0.21 M Fe(NO3)3.9H2O (Fluka) for 1 h and cooled, and the brown precipitate was dispersed in H2O and then dialyzed for 2 days against 0.01 M nitric acid. The dialyzed iron oxide nanoparticles were mixed with the various polyvinyl alcohol (PVA) polymers as described previously (Chastellain et al., 2004; Petri-Fink et al., 2005), and the pH was adjusted to 7 to obtain PVA-coated nanoparticles, either native-, aminoPVA-, carboxylatePVA-, or thiolPVA-SPIONs. For the experiments described here, the ratio of polymer/iron was 10 (45 mg of polymer/ml and 4.5 mg of iron/ml, final concentrations), and the ratio of PVA/functionalized PVA copolymer was 45 (mass ratio). Dextran-coated Endorem (Endorem, Guerbet, G 534-14, lot 134, 11.2 mg of iron/ml) and Sinerem (Ferumoxtran-10, AMI227, Guerbet, G534-25, lot ADS03, 20 mg of iron/ml) were provided by Guerbet, France. The various nanoparticles used in this study and their biochemical characteristics are summarized in Table 1 and Fig. 1. Cy3.5-SPIONs or Cy5.5-SPIONs were prepared by reacting under shaking 500 µl of aminoPVA-SPIONs (2-5 x 1015 nanoparticles/ml, 4.5 mg of iron/ml) with 500 µl of Cy3.5-N-hydroxy-succinimide ester or Cy5.5-N-hydroxy-succinimide ester (30 mmol NH2-labeling capacity, Cy3.5- or Cy5.5-monoreactive dye; Amersham Biosciences, Uppsala, Sweden) in 25 mM sodium carbonate buffer, pH 9.5, for 2 h in the dark at room temperature, followed by sequential gel filtration through pre-packed Sephadex G-25 columns (8.3-ml bed volume) (Amersham Biosciences), first in 25 mM sodium phosphate buffer, pH 7.5, then in nanopure water.
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Cells and Cell Culture Treatments with the Various Nanoparticles. The characteristics and culture conditions of the rat brain-derived endothelial EC219 (Juillerat-Jeanneret et al., 1992, 2003) and the murine N9 and N11 microglial (Murata et al., 1994, 1997) (kindly provided by P. Ricciardi-Castagoli, Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Centre, Milan, Italy) cell lines have been described. EC219, N9, and N11 cells were previously shown to produce nitric oxide under inflammatory stress (Murata et al., 1994, 1997). Cells were routinely maintained in their culture medium containing FCS and antibiotics (both from Gibco, Invitrogen, Basel, Switzerland). Three days prior to experiments, the cells were detached in trypsin-EDTA (Gibco) and grown in complete medium in 96- or 48-well plates (Costar, Corning, NY). On the day of the experiment, medium was changed to fresh complete medium, and the various nanoparticles preparations (cf. above) were added for the concentration, time, and temperature indicated, together with 1 µg/ml lipopolysaccharide (LPS; Sigma, Buchs, Switzerland) when indicated. At the end of the experiment, either the 3-(4,5-dimethylthiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT; Sigma) test was performed for the last 2 h to determine cell viability (cf. below) or the cell layers were washed twice in saline, or when indicated for 5 min at room temperature in 0.15 M sodium acetate buffer, pH 5.2, to remove cell surface nanoparticles, and cellular iron content was quantified (cf. below). Alternatively, histological staining of iron or confocal microscopy was performed (cf. below).
Aggregate Cultures and Treatments. Brain cell-derived aggregates were prepared from the telencephalon of E16 rat embryos (OFA/SPF; BRL, Füllinsdorf, Switzerland) and maintained in defined medium under continuous gyratory agitation, essentially as described previously (Honegger and Tschudi-Monnet, 2000). On days 7, 14, 21, or 28, aminoPVA-SPIONs (2.5 µl of nanoparticles/ml culture medium, 11.3 µg of iron/ml) were added to the aggregates for 48 h, and then 5 of 8 ml per flask of culture medium was changed to fresh medium containing aminoPVA-SPIONs at the same concentration for another 24 h. Then, of 8 ml, 5 ml/flask were replaced by fresh culture medium without SPIONs, and the culture was continued for 48 h. Aggregates were harvested by sedimentation, the culture supernatants were frozen (for further determinations of NO), and the aggregates were washed in PBS, embedded (Tissue-Tek; Sakura, Zoeterwoude, The Netherlands), and frozen in isopentane cooled in liquid nitrogen for histochemistry. This model has been shown previously to be relevant in the evaluation of brain inflammation (Juillerat-Jeanneret et al., 2003).
Evaluation of Cell Viability, Protein Content, and NO. The evaluation of 3-(4,5-dimethylthiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction to quantify metabolically active cells was performed essentially as described previously (Petri-Fink et al., 2005). Cell layers were extracted in PBS-0.1% Triton X-100, and protein content was quantified with the BCA kit (Pierce, Socochim, Lausanne, Switzerland) and bovine serum albumin as standard. The production of NO was measured in culture supernatants as the stable NO derivative NO2- with the Griess reagent, essentially as described previously (Murata et al., 1994).
Total Cell Iron Determination. The cell layer was dissolved for 1 h in 6 N HCl (125 µl/well of a 48-well plate), then 125 µl of a 5% solution of K4[Fe(CN)6].3H2O (Merck, Dietikon, Switzerland) in H2O was added for 10 min, and the absorbance was read at 690 nm in a multiwell plate reader (iEMS Labsystems, BioConcepts, Allschwil, Switzerland). A standard curve of an aqueous FeCl3·6H2O (Merck) solution was treated in the same conditions to quantify the amount of cell-bound iron.
Histochemical Determination of Iron. Histological sections (5 µm) of frozen aggregates were cut, or cells were grown on histological glass slides in medium containing 10% FCS and antibiotics. Then medium was changed to fresh complete medium containing 1 µl of aminoPVA-SPION (4.5 µg of iron/ml culture medium) for 5 to 240 min at 37°C, the medium was aspirated, and the cell layer was washed three times, fixed for 15 min in 4% buffered paraformaldehyde at room temperature, washed, and air-dried. The cell layer was exposed for 15 to 30 min at room temperature to a 1:1 solution of 1 N HCl and 10% K4 [Fe(CN)6] (Fluka) in H2O, washed in distilled water, counterstained with Nuclear Fast Red, dehydrated in graded alcohol, and mounted. Slides were photographed under a Nikon digital camera (DXM 1200; Nikon Corporation, Tokyo, Japan).
Lectin Histochemistry. Histological sections (5 µm) of aggregates were postfixed for 15 min in 4% buffered paraformaldehyde and incubated overnight at 4°C in a solution of horseradish peroxidase-conjugated Bandeirea simplicifolia-1 lectin (Sigma, 12.5 µg/ml in 0.1 M Tris-NaCl-1% Triton X-100, pH 7.4), then exposed to 0.002% diaminobenzamidine (Fluka) and counterstained with hematoxylin (Honegger and Tschudi-Monnet, 2000; Juillerat-Jeanneret et al., 2003).
Confocal Microscopy. N9 murine microglial cells were grown in Iscove's modified Dulbecco's medium (Sigma) containing 5% FCS and free of phenol red. Two hours prior to treatments, cells were washed, and media were replaced with FCS-free media. Cells were seeded into eight-well chambers (Lab-Tek; Nalge Nunc International, Rochester, NY) at a density of 105 cells/cm2. Cy3.5-aminoPVA-SPIONs were added (20 µg of iron/ml final concentration), and cells were incubated for different time periods from 1 min to 20 h. Plasma membranes were labeled with 1 µM 5-dodecanoyl-aminofluorescein (DAF; Molecular Probes, Eugene, OR) and nuclei using 4',6-diamidine-2'-phenylindole (DAPI) staining (10 µM, 10 min; Sigma). Cells were washed once either with PBS or acidified wash (0.5 M NaCl, 0.2 M CH3COOH, pH 2.5), once with PBS, and then once with FCS-free medium to remove any nonspecifically adsorbed SPIONs or free fluorescent dye. No background cell fluorescence was detected under the settings used. Microscopy was performed using a confocal laser scanning LSM 510 Zeiss microscope (Carl Zeiss GmbH, Jena, Germany) equipped with the following lasers: HeNe LASOS LGK 7786 P/Power supply, 7460 A, 543 nm, 1 mW; Argon LASOS LGK 7812 ML-1/LGN, 458, 488, 514 nm, 25 mW, Laser class 3D; and Titanium-Sapphire The Coherent Mira model 900-f Laser tunable from 710 to 1000 nm for two-photon microscopy (set to pulse at 800 nm). Excitation/emission maxima for the dyes are: DAF, 495/518 nm; DAPI, 358/461 nm; and Cy3.5, 581/596 nm.
Animal Evaluations. C57BL6 mice (6-8 weeks old; Charles River/Iffa Credo, Lyon, France) were injected on day 0 with Cy5.5-aminoPVA-SPIONs (3 mg of iron/kg body weight, adjusted to 100 µl/mouse with sterile PBS; stock solution of Cy5.5-aminoPVA-SPIONs, 4.5 mg of iron/ml) and examined 24 h later, then killed, and the brains were either frozen or fixed for 48 h in buffered formaldehyde and embedded in paraffin. Histological sections (5 µm) were cut, and Prussian Blue histological determination of iron was performed as described above. Frozen samples were cut at 8 µm mounted in Fluoromount-G (SouthernBiotech, Birmingham, AL) and examined under a fluorescence microscope. This protocol has been approved by the Ethics Committee for Animal Experimentation of the Canton of Geneva.
Calculations of Results. Each experiment was repeated in triplicate wells at least two times. Means and S.D. were calculated. For confocal microscopy, data were analyzed using SYSTAT 10 (SPSS, Chicago, IL). Statistical significance was determined by analysis of variance followed by post hoc Tukey's test. Differences were considered significant where p < 0.05.
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To further determine the effects of the SPION particle size and of inflammatory cell activation for efficient cell uptake, we evaluated whether dextran-coated SPIONs with a larger hydrodynamic size (beads) (Endorem, hydrodynamic diameter 80-150 nm) would display an increased uptake by EC219 and N11 cells, either resting or LPS-activated cells (Table 4). In EC219 endothelial cells, Endorem uptake was low and did not increase with time of exposure or the presence of LPS (Table 4); however, endothelial cells did respond to LPS by increasing NO release (data not shown). We have shown previously that EC219, N9, and N11 cells respond to inflammatory stimuli, including LPS, by producing NO (Murata et al., 1994, 1997). In N11 microglial cells, spontaneous uptake was slow but increased with time (Table 4), the amount of Endorem added to the cells (Fig. 2). LPS addition to N11 cells increased SPION uptake (Table 4) and NO release (data not shown). However, LPS addition must be performed simultaneously and not 24 h prior to Endorem addition to observe such an effect. However, whatever the culture conditions, only a low percentage (less than 1%) of Endorem added to microglial cells was taken up by these cells.
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Therefore, the uptake of dextran-coated SPIONs by brain-derived cells was slow and low, whatever the hydrodynamic size of the SPIONs and the cell activation state. These characteristics make these particles well suited for magnetic imaging but not for tissue and intracellular drug delivery. Thus, we evaluated whether modification of the polymer coating of SPIONs would improve their interaction with brain-derived cells, as previously shown for human melanoma cells (Petri-Fink et al., 2005).
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). In this model, dissociated embryonic neural cells are reassociated under gyratory culture conditions, and astrocytes, neuron, oligodendrocytes, and microglial cells differentiate with the time in culture (Honegger and Tschudi-Monnet, 2000). After 1 (undifferentiated aggregates) to 4 (differentiated aggregates) weeks in culture, aggregates were exposed to aminoPVA-SPIONs and histological iron determination and BS-1 lectin staining (an histological marker of microglial activation) as well as determination of NO in the aggregate culture medium were performed. Different patterns of iron staining were observed with the stages of differentiation; however, at any stage, only the tanycytes (the specific astrocytic cell external layer of brain ventricles) of aggregates demonstrated detectable iron uptake (Fig. 7A), and no deep brain aggregate penetration was observed. At early differentiation stages (1-2 weeks), iron staining was more irregular and sometimes located in cells of the second layer of the aggregates, whereas at higher differentiation stages (3-4 weeks), when the aggregates structures are well organized, iron staining was observed only in cells of the external layer. No increase in BS-1 lectin staining was observed at any stage of differentiation (Fig. 7B, 2 weeks, other stages not shown), and NO was not detected in the aggregate culture medium (data not shown), confirming the absence of inflammatory activation and the biocompatibility of these nanoparticles for brain tissue.
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To evaluate biocompatibility in vivo, we injected normal mice with aminoPVA-SPIONs at a concentration comparable with the iron dosages used in patients for MRI-enhanced evaluation of liver disorders. Following i.v. injection of Cy5.5-aminoPVA-SPIONS into mice, no massive blood clotting or renal, hepatic, cardiovascular, or respiratory side effects for at least 24 h were observed demonstrating in vivo biocompatibility. Histological determination of iron demonstrated SPIONs capture in spleen > liver > brain = kidney. In the brain, only scattered SPIONs particles could be detected (data not shown).
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), a highly specialized vascular system consisting of endothelial cells, pericytes, and astrocytes. The presence of tight junctions between cells of the BBB protects the brain from blood-borne pathogens and chemicals but also impedes the access of therapeutic drugs. In certain disorders, however, such as neurodegeneration and brain cancer, the BBB becomes compromised, which creates a window for drug delivery (Muldoon et al., 1999; Lockman et al., 2004). Alternatively, therapeutics agents can be transported across an intact BBB by hijacking the endogenous transport systems of the cerebral vasculature (Lockman et al., 2003). Another approach to drug delivery to the brain is to use the connection that exists between the nervous and olfactory systems (Borm and Kreyling, 2004). Regardless of the route used to deliver drugs into the brain, the diffusion of the drug delivery devices into the brain parenchyma must be controllable and must avoid activation of microglial cells, since the brain possesses its own macrophage population, the microglia, which are involved in the development of neurodegenerative disorders (Perry et al., 1993) and could be activated by the treatments. Macrophages in inflammatory areas, from the brain or other tissues, are main targets for nanoparticles, whether magnetic or not (Ruehm et al., 2001; Corot et al., 2004; Raynal et al., 2004; Triverdi et al., 2004; Chellat et al., 2005). In the present manuscript, our experimental approaches were designed to evaluate whether intracellular uptake by brain cells of functionalized SPIONs is possible and would be harmful and inflammation-inducing for brain-derived cells and structures and whether massive invasion of the brain would be observed, which is not a desirable effect.
Therefore, our goals in the present study were to define the biophysical, biological, and biochemical characteristics of SPIONs with such properties. Using the rat brain-derived EC219 endothelial cells, the murine N9 and N11 microglial cells, and differentiating aggregate brain cells in three-dimensional cultures, we have evaluated the cellular uptake, the cytotoxicity, and the interaction of these cells with various nanoparticles. Macrophages and endothelial cells express organ-specific properties, but macrophages and endothelial cells of rodent origin (Murata et al., 1994, 1997), as well as rodent brain-cells in aggregate culture (Juillerat-Jeanneret et al., 2003), have been shown to produce nitric oxide following stimulation, which represents a convenient way to evaluate their activation following exposure to SPIONs. SPIONs coated with dextran polymer, either ultrasmall, 
30 nm, or beads of 80 to 150 nm were well tolerated by endothelial and microglial cells, but their cellular uptake was low. Ultrasmall, 40-nm SPIONs coated with either PVA or with PVA that was derivatized on the hydroxyl groups with either carboxylate or thiol groups were well tolerated by cells, but no cell uptake was observed. AminoPVA-SPIONs were internalized, core iron oxide and polymer, by cerebral cells, either isolated cells in two-dimensional culture, or differentiated cells in three-dimensional aggregate cultures. Cationic molecules display increased cell uptake but may also display increased cytotoxicity. Importantly, no cellular reaction was observed following cellular uptake of aminoPVA-SPIONs, as estimated by nitric oxide production or the evaluation of microglial activation. These nanoparticles were also well tolerated when injected into normal mice.
Previous experiments using magnetic approach to drug targeting have been performed by some groups with magnetic particles or magnetic liposomes ranging from 10 µm to 100 nm, loaded with chemotherapeutic agents (Alexiou et al., 2000; Rudge et al., 2001). Some positive effects were obtained, in particular, a decrease of general toxicity of the agents, due to generally lower doses required. Magnetically controlled drug targeting and delivery requires magnetic nanoparticles with high magnetization properties and the possibility of surface derivatization for drug attachment to achieve magnetic drug delivery. SPIONs, or super paramagnetic nanoparticles with an iron oxide core diameter of less than 10 nm, exhibit outstanding magnetic properties because they show no magnetization in the absence of a magnetic field but become strongly magnetized in the presence of one. Biocompatible superparamagnetic nanoparticles have been developed for in vivo biomedical applications mainly in magnetic resonance imaging (Weissleder et al., 1997) and have only been evaluated preclinically in tissue-specific delivery of therapeutic agents (Lubbe et al., 1996). Two advantages of SPIONs are their low toxicity to humans and the possibility to exploit their superparamagnetic properties (Weissleder et al., 1997; Ruehm et al., 2001; Brigger et al., 2002; Hoehn et al., 2002; Kircher et al., 2003; Corot et al., 2004; Neuwelt et al., 2004; Raynal et al., 2004; Sundstrom et al., 2004; Triverdi et al., 2004; Daldrup-Link et al., 2005). Although the use of SPIONs as magnetic resonance imaging contrast agents is established, their potential as drug targeting and drug delivery agents is still in the early stage of evaluation.
In drug delivery application, the critical step is the transport across cell layers (Koch et al., 2005) and the internalization of nanoparticles into specific cells, a process often limited by poor targeting specificity and low internalization efficiency of therapeutic ligands grafted on the nanoparticles. A number of studies have addressed the cell-surface binding or cell uptake of functionalized SPIONs. Surface modification of the polyethyleneglycol film of SPIONs with folic acid was shown to decrease their uptake by mouse macrophages and increase their uptake by human cancer cells (Zhang et al., 2002), and albumin coating of anionic SPIONs led to internalization by cells (Wilhelm et al., 2003). Dextran-coated SPIONs of 150 nm, but not of 10 nm, were shown to be taken up by macrophages in a process involving types I and II scavenger receptor-mediated endocytosis (Raynal et al., 2004). Macaque T cells labeled with monocrystalline SPIONs following adsorptive pinocytosis or receptor-mediated endocytosis and which localized in the cytoplasm did not cause any measurable effects on T cell function (Sundstrom et al., 2004). Therefore, highly specific biological, biochemical, and biophysical properties are required to develop drug-derivatized SPIONs that can detect lesions and that are capable of tissue- and cell-selective drug delivery. The detection systems must be noninvasive, and the agents allowing detection must be biocompatible and biodegradable. In addition, cell activation and the production of inflammatory molecules must be avoided. Polymeric coating of SPIONs has been used to prevent nanoparticle aggregation in biological media to achieve noninvasive detection system in enhanced magnetic imaging. Once directed toward the target cells, the functionalized SPIONs can be immobilized at a particular site using external magnetic fields, thus providing an additional degree of control over the drug delivery. In addition, varying the biochemical characteristics of the coating polymer may allow for selective intracellular or extracellular delivery of the drugs to the target cells.
In conclusion, the successful development of biocompatible functionalized SPIONs capable of intracellular uptake by cells depends on several factors including size, surface area-to-volume ratio, physicochemical and biochemical properties of the coating shell, and the cell type. When aminoPVA-SPIONs were taken up by brain-derived structures, no evidence of inflammatory reaction was observed, and no massive and deep invasion of the brain was observed. Injection of aminoPVA-SPIONs in normal mice demonstrated biocompatibility in living animals. The observation using Endorem and Sinerem that vascular leakage associated with multiple sclerosis and its experimental models can be documented suggests that under pathological circumstances, access to the brain of SPIONs can be obtained. Alternatively, drugs could be released from their carrier following uptake by the brain vasculature and diffuse to brain parenchyma, since the brain is one of the most densely vascularized organ, and it is assumed that each vessel is separated from its neighbor by around 40 µm, which means that every neural cell almost has its private vessel and that once a drug has traversed the blood brain barrier, its brain distribution is immediate. Therefore, these nanostructures represent useful tools for further development of nanostructures able of intracellular delivery of therapeutic agents to brain cells.
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Acknowledgements |
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Footnotes |
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
ABBREVIATIONS: SPION, Super Paramagnetic Iron Oxide Nanoparticle; MRI, magnetic resonance imaging; PVA, polyvinyl alcohol; FCS, fetal calf serum; LPS, lipopolysaccharide; PBS, phosphate-buffered saline; DAF, 5-dodecanoyl-aminofluorescein; DAPI, 4',6-diamidine-2'-phenylindole; BBB, blood-brain barrier.
Address correspondence to: Dr. Lucienne Juillerat, University Institute of Pathology, Bugnon 25, CH-1011 Lausanne, Switzerland. E-mail: lucienne.juillerat{at}chuv.ch
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References |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
Alexiou C, Arnold W, Klein RJ, Parak FG, Hulin P, Bergemann C, Erhardt W, Wagenpfeil S, and Lübbe AS (2000) Locoregional cancer treatment with magnetic drug targeting. Cancer Res 60: 6641-6648.
Borm PJ and Kreyling W (2004) Toxicological hazards of inhaled nanoparticles-potential implications for drug delivery. J Nanosci Nanotechnol 4: 521-531.[CrossRef][Medline]
Brigger I, Dubernet C, and Couvreur P (2002) Nanoparticles in cancer therapy and diagnosis. Adv Drug Deliv Rev 54: 631-651.[CrossRef][Medline]
Chastellain M, Petri A, and Hofmann H (2004) Particle size investigations on a multi-step synthesis of PVA coated superparamagnetic nanoparticles. J Colloid Interface Sci 278: 353-360.[Medline]
Chellat F, Merhi Y, Moreau A, and Yahia L (2005) Therapeutic potential of nanoparticulate systems for macrophage targeting. Biomaterials 26: 7260-7275.[CrossRef][Medline]
Colvin VL (2003) The potential environmental impact of engineered nanomaterials. Nat Biotech 21: 1166-1170.[CrossRef][Medline]
Corot C, Petry KG, Trivedi R, Saleh A, Jonkmanns C, Le Bas JF, Blezer E, Rausch M, Brochet B, Foster-Gareau P, et al. (2004) Macrophage imaging in central nervous system and in carotid atherosclerotic plaque using ultrasmall superparamagnetic iron oxide in magnetic resonance imaging. Investig Radiol 39: 619-625.[CrossRef][Medline]
Daldrup-Link HE, Rudelius M, Piontek G, Metz S, Brauer R, Debus G, Corot C, Schlegel J, Link TM, Peschel C, et al. (2005) Migration of iron oxide-labeled human hematopoietic progenitor cells in a mouse model: in vivo monitoring with 1.5-T MR imaging equipment. Radiology 234: 197-205.
Hoehn M, Kustermann E, Blunk J, Wiedermann D, Trapp T, Wecker S, Focking M, Arnold H, Hescheler J, Fleischmann BK, et al. (2002) Monitoring of implanted stem cell migration in vivo: a highly resolved in vivo magnetic resonance imaging investigation of experimental stroke in rat. Proc Natl Acad Sci USA 99: 16267-16272.
Hoet PHM, Brüske-Hohlfeld I, and Salata OV (2004) Nanoparticles— known and unknown health risks. J Nanobiotechnol 2: 12-27.
Honegger P and Tschudi-Monnet F (2000) Aggregating neural cell cultures, in Protocols for Neural Cell Culture (Fedoroff S and Richardson A eds) pp 199-218, Humana Press, Inc., Totowa, NJ.
Juillerat-Jeanneret L, Aguzzi A, Wiestler OD, Darekar P, and Janzer RC (1992) Dexamethasone regulates the activity of enzymatic markers of cerebral endothelial cell lines. In Vitro Cell Dev Biol 28A: 537-543.
Juillerat-Jeanneret L, Monnet-Tschudi F, Zürich MG, Lohm S, Duijvestijn AM, and Honegger P (2003) Regulation of peptidase activity in a three-dimensional aggregate model of brain tumor vasculature. Cell Tissue Res 311: 53-59.[Medline]
Kandimalla KK and Donovan MD (2005) Carrier mediated transport of chlorpheniramine and chlorcyclizine across bovine olfactory mucosa: implications on nose-to-brain transport. J Pharm Sci 94: 613-624.[Medline]
Kircher MF, Mahmood U, King RS, Weissleder R, and Josephson L (2003) A multi-modal nanoparticle for preoperative magnetic resonance imaging and intraoperative optical brain tumor delineation. Cancer Res 63: 8122-8125.
Koch AM, Reynolds F, Merkle HP, Weissleder R, and Josephson L (2005) Transport of surface-modified nanoparticles through cell monolayers. Chem Biol Chem 6: 337-345.
Kreuter J (2004) Influence of the surface properties on nanoparticle-mediated transport of drugs to the brain. J Nanosci Nanotechnol 4: 484-488.[CrossRef][Medline]
Lockman PR, Koziara JM, Mumper RJ, and Allen DD (2004) Nanoparticle surface charges alter blood-brain barrier integrity and permeability. J Drug Target 12: 635-641.[CrossRef][Medline]
Lockman PR, Oyewumi MO, Koziara JM, Roder KE, Mumper RJ, and Allen DD (2003) Brain uptake of thiamine-coated nanoparticles. J Control Rel 93: 271-282.[CrossRef][Medline]
Lubbe AS, Bergemann C, Huhnt W, Fricke T, Riess H, Brock JW, and Huhn D (1996) Preclinical experiences with magnetic drug targeting: tolerance and efficacy. Cancer Res 56: 4694-4701.
Massart R, Dubois E, Cabuil V, and Hasmonay E (1995) Preparation and properties of monodisperse magnetic fluids. J Magn Magn Mater 149: 1-5.[Medline]
Muldoon LL, Pagel MA, Kroll RA, Roman-Goldstein S, Jones RS, and Neuwelt EA (1999) A physiological barrier distal to the anatomic blood-brain barrier in a model of transvascular delivery. Am J Neuroradiol 20: 217-222.
Muller RH and Keck CM (2004) Drug delivery to the brain: realization by novel drug carriers. J Nanosci Nanotechnol 4: 471-483.[Medline]
Murata JI, Betz Corradin S, Janzer RC, and Juillerat-Jeanneret L (1994) Tumor cells suppress cytokine-induced nitric oxide (NO) production in cerebral endothelial cells. Int J Cancer 59: 699-705.[Medline]
Murata JI, Ricciardi-Castagnoli P, Dessous L'Eglise Mange P, Martin F, and Juillerat-Jeanneret L (1997) Microglial cells induce cytotoxic effects towards colon carcinoma cells: measurement of tumor cytotoxicity with a g-glutamyl transpeptidase assay. Int J Cancer 70: 169-174.[Medline]
Neuwelt EA, Varallyay P, Bago AG, Muldoon LL, Nesbit G, and Nixon R (2004) Imaging of iron oxide nanoparticles by MR and light microscopy in patients with malignant brain tumors. Neuropathol Appl Neurobiol 30: 456-471.[CrossRef][Medline]
Obersdörster G, Sharp Z, Atudorei V, Elder A, Gelein R, Kreyling W, and Cox C (2004) Translocation of inhaled ultrafine particles to the brain. Inhalation Toxicol 16: 437-445.[CrossRef][Medline]
Perry VH, Andersson PB, and Gordon S (1993) Macrophages and inflammation in the central nervous system. Trends Neurol Sci 16: 268-273.[CrossRef][Medline]
Petri-Fink A, Chastellain M, Juillerat-Jeanneret L, Ferrari A, and Hofmann H (2005) Development of functionalized superparamagnetic iron oxide nanoparticles for interaction with human cancer cells. Biomaterials 26: 639-646.
Raynal I, Rrigent P, Peyramaure S, Najid A, Rebuzzi C, and Corot C (2004) Macrophage endocytosis of superparamagnetic iron oxide nanoparticles: mechanisms and comparison of ferumoxides and ferumoxtran-10. Investig Radiol 39: 56-63.[CrossRef][Medline]
Risau W and Wolburg W (1990) Development of blood-brain barrier. Trends Neurol Sci 13: 174-178.[CrossRef][Medline]
Rudge S, Peterson C, Vessely C, Koda J, Stevens S, and Catterall L (2001) Adsorption and desorption of chemotherapeutic drugs from a magnetically targeted carrier (MTC). J Control Rel 74: 335-340.[CrossRef][Medline]
Ruehm SG, Corot C, Vogt P, Kolb S, and Debatin JF (2001) Magnetic resonance imaging of atherosclerotic plaque with ultrasmall superparamagnetic particles of iron oxide in hyperlipidemic rabbits. Circulation 103: 415-422.
Savic R, Luo L, Eisenberg A, and Maysinger D (2003) Micellar nanocontainers distribute to defined cytoplasmic organelles. Science (Wash DC) 300: 615-618.
Sundstrom JB, Mao H, Santoianni R, Villinger F, Little DM, Huynh TT, Mayne AE, Hao E, and Ansari AA (2004) Magnetic resonance imaging of activated proliferating rhesus macaque T cells labeled with superparamagnetic monocrystalline iron oxide nanoparticles. J Acquir Immune Defic Syndr 35: 9-21.[Medline]
Triverdi RA, U-King-Im JM, Graves MJ, Cross JJ, Horsley J, Goddard MJ, Skepper JN, Quartey G, Warburton E, Joubert I, et al. (2004) In vivo detection of macrophages in human carotid atheroma: temporal dependence of ultrasmall superparamagnetic particles of iron oxide-enhanced MRI. Stroke 35: 1631-1635.
van Ewijk GA, Vroege GJ, and Philipse AP (1999) Convenient preparation methods for magnetic colloids. J Magn Magn Mater 201: 31-33.[CrossRef]
Weissleder R, Cheng HC, Bogdanova A, and Bogdanov A (1997) Magnetically-labeled cells can be detected by MR imaging. J Magn Reson Imaging 7: 258-263.[Medline]
Wilhelm C, Billotey C, Roger J, Pons JN, Bacri JC, and Gazeau F (2003) Intracellular uptake of anionic superparamagnetic nanoparticles as a function of their surface coating. Biomaterials 24: 1001-1011.[CrossRef][Medline]
Zhang Y, Kohler N, and Zhang M (2002) Surface modification of superparamagnetic magnetite nanoparticles and their intracellular uptake. Biomaterials 23: 1553-1561.[CrossRef][Medline]
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: size distribution; 
: dye/particles ratio. B and C, cells were grown in culture medium in culture wells, then exposed to Cy3.5-SPIONs (4-83 µg of iron/ml, final concentration) for 2 or 4 h, either at 4 or 37°C. Then, following extensive washing, Cy3.5 fluorescence was measured in the intact cell layer (B), followed by cellular iron content determined using Prussian Blue reaction (C) in cell extracts.
