Cell type-specific response to high intracellular loading of polyacrylic acid-coated magnetic nanoparticles

Abstract

Magnetic nanoparticles (NPs) are a special type of NP with a ferromagnetic, electron-dense core that enables several applications such as cell tracking, hyperthermia, and magnetic separation, as well as multimodality. So far, superparamagnetic iron oxide NPs (SPIONs) are the only clinically approved type of metal oxide NPs, but cobalt ferrite NPs have properties suitable for biomedical applications as well. In this study, we analyzed the cellular responses to magnetic cobalt ferrite NPs coated with polyacrylic acid (PAA) in three cell types: Chinese Hamster Ovary (CHO), mouse melanoma (B16) cell line, and primary human myoblasts (MYO). We compared the internalization pathway, intracellular trafficking, and intracellular fate of our NPs using fluorescence and transmission electron microscopy (TEM) as well as quantified NP uptake and analyzed uptake dynamics. We determined cell viability after 24 or 96 hours’ exposure to increasing concentrations of NPs, and quantified the generation of reactive oxygen species (ROS) upon 24 and 48 hours’ exposure. Our NPs have been shown to readily enter and accumulate in cells in high quantities using the same two endocytic pathways; mostly by macropinocytosis and partially by clathrin-mediated endocytosis. The cell types differed in their uptake rate, the dynamics of intracellular trafficking, and the uptake capacity, as well as in their response to higher concentrations of internalized NPs. The observed differences in cell responses stress the importance of evaluation of NP–cell interactions on several different cell types for better prediction of possible toxic effects on different cell and tissue types in vivo.

Dispersion of Nanoparticles in Different Media Importantly Determines the Composition of Their Protein Corona

“…There was almost complete absence of apolipoproteins in the corona of PAA NPs, with the exception of apolipoprotein A-I found in the corona of NPs dispersed in NaCl. Although there are some implications that apolipoprotein A-I is connected to bioaccumulation of NPs in cells [7] our PAA NPs were shown to accumulate in different cell lines despite of the absence of this specific protein in their corona [38,53]. Again, dispersion media proved to be a relevant factor in determining the NPs protein corona composition.…”

Proposing Urothelial and Muscle In Vitro Cell Models as a Novel Approach for Assessment of Long-Term Toxicity of Nanoparticles

“…In general, aggregated industrial SiO 2 induced small toxic effects only at extremely high concentration, while relatively stable TiO 2 and magnetic PAA NPs that could be internalized had several effects also at moderate concentrations. The short-term exposure (96 h) of L6 cells to TiO 2 induced a significant decrease in viability, and the highest concentration of PAA NPs induced a drop in L6 cell viability (statistically not significant) similarly as already observed on primary human myoblasts [ 56 ]. The drop in viability was probably due to membrane damage in case of magnetic PEI NPs, while for other NPs, there is little effect due to membrane damage (low percentage of PI positive cell), and effects are mostly on cell proliferation as already shown for magnetic PAA [ 56 , 67 ].…”

“…A continuous exposure simulated events of repeated or continuous exposure to NPs due to the presence of NPs in different consumer products or environmental pollution. We used four types of NPs: two biomedically relevant (magnetic PAA and PEI) NPs [ 8 , 56 , 57 , 58 , 59 ] and industrially relevant (SiO 2 and TiO 2 ) NPs as representative types of two very commonly used commercial NPs in various consumer products and materials. We analyzed the effects of NPs on the cell viability, morphology, and ultrastructure on both cell models.…”

“…Magnetic PAA NPs are negatively charged and highly stable in physiological conditions, but they are less stable at high calcium concentration ( Table 1 ) [ 3 ]. As already described, they are short-term nontoxic and can be internalized in high quantities [ 56 , 60 ]. On the other hand, due to their highly positive zeta potential, [ 61 , 62 ] magnetic PEI NPs aggregated, and their size increased up to 10 times when dissolved in cell culture media due to the formation of biocorona and aggregation [ 4 , 62 ].…”

Nanoparticles and clinically applicable cell tracking

“…In various studies, it was also shown that next to uptake efficiency of particles, the extent of the adverse effects could also be strongly cell type dependent. 78,99,121,122 Because of these findings there is a continued effort in trying to generate more stable particles and/or particles with an improved balance between core composition and coating. 77,114,[123][124][125] In our group, we made the observation that for a liposomal encapsulated gadolinium particle, adverse effects on cellular functionality was more directly associated with the liposomal capsule than with the chelated gadolinium molecules.…”