Characterization of cellular uptake and toxicity of aminosilane-coated iron oxide nanoparticles with different charges in central nervous system-relevant cell culture models

Abstract

Background: Aminosilane-coated iron oxide nanoparticles (AmS-IONPs) have been widely used in constructing complex and multifunctional drug delivery systems. However, the biocompatibility and uptake characteristics of AmS-IONPs in central nervous system (CNS)-relevant cells are unknown. The purpose of this study was to determine the effect of surface charge and magnetic field on toxicity and uptake of AmS-IONPs in CNS-relevant cell types. Methods: The toxicity and uptake profile of positively charged AmS-IONPs and negatively charged COOH-AmS-IONPs of similar size were examined using a mouse brain microvessel endothelial cell line (bEnd.3) and primary cultured mouse astrocytes and neurons. Cell accumulation of IONPs was examined using the ferrozine assay, and cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results: No toxicity was observed in bEnd.3 cells at concentrations up to 200 µg/mL for either AmS-IONPs or COOH-AmS-IONPs. AmS-IONPs at concentrations above 200 µg/mL reduced neuron viability by 50% in the presence or absence of a magnetic field, while only 20% reductions in viability were observed with COOH-AmS-IONPs. Similar concentrations of AmS-IONPs in astrocyte cultures reduced viability to 75% but only in the presence of a magnetic field, while exposure to COOH-AmS-IONPs reduced viability to 65% and 35% in the absence and presence of a magnetic field, respectively. Cellular accumulation of AmS-IONPs was greater in all cell types examined compared to COOH-AmS-IONPs. Rank order of cellular uptake for AmS-IONPs was astrocytes . bEnd.3 . neurons. Accumulation of COOH-AmS-IONPs was minimal and similar in magnitude in different cell types. Magnetic field exposure enhanced cellular accumulation of both AmS-and COOH-AmS-IONPs. Conclusion: Both IONP compositions were nontoxic at concentrations below 100 µg/mL in all cell types examined. At doses above 100 µg/mL, neurons were more sensitive to AmS-IONPs, whereas astrocytes were more vulnerable toward COOH-AmS-IONPs. Toxicity appears to be dependent on the surface coating as opposed to the amount of iron-oxide present in the cell.

‘Stealth’ nanoparticles evade neural immune cells but also evade major brain cell populations: Implications for PEG-based neurotherapeutics

“…ML-MM is a chemically-defined, serum-free preparation. Particle characterization measurements of bare nanoparticles are commonly conducted in PBS/deionized water [44,45], but cannot address alterations in particle properties that occur in complex biological growth media, which are of higher predictive value for the in vivo situation.…”

Flow cytometry for intracellular SPION quantification: specificity and sensitivity in comparison with spectroscopic methods

“…35 In endothelial cells, treatment with up to 100 μg Fe /mL SPIONs was well tolerated, although cellular uptake was not determined in that study. 36 During clinical applications like magnetic resonance imaging or magnetic hyperthermia, SPIONs come into direct contact with endothelial cells when administered into veins or arteries. We therefore investigated SPION accumulation/ uptake in endothelial cells, which are the first contact cells for all nanoparticles intended for intravascular administration.…”

“…36 However, to obtain a better understanding of the influence of nanoparticles on cells, it is crucial to gather all relevant concentration parameters, such as μg Fe /mL media, μg Fe /cm 2 plate surface, and pg Fe /cell and, above all, the respective cell number of the measured sample. The methods applied in our study aimed at quantification of cell numbers in parallel with the measurement of SPION content, in order to correlate the cellular effects with the average amount of SPIONs per cell.…”

Ultrasmall cationic superparamagnetic iron oxide nanoparticles as nontoxic and efficient MRI contrast agent and magnetic-targeting tool

“…On the other hand, Marcu et al 16 targeted a MCF-17 breast cancer cell line delivering iron oxide nanoparticles loaded with Violamycine B1, an anthracycline antibiotic that enhanced cellular uptake activity and cell death. Sun et al 17 showed that toxicity depends more strongly on the surface coating than the amount of iron oxide present in the cell. Also, SPIOs coated with amino or carboxylate groups were shown to be nontoxic against a mouse brain microvessel endothelial cell line (bEnd.3) and primary culture of mouse astrocytes and neurons, at concentrations below 100 µg/mL.…”