Nanoparticles have become popular in life sciences in the last few years. They have been produced in many variants and have recently been used in both biological experiments and in clinical applications. Due to concerns over nanomaterial risks, there has been a dramatic increase in investigations focused on safety research. The aim of this paper is to present the advanced testing of rhodamine-derived superparamagnetic maghemite nanoparticles (SAMN-R), which are used for their nontoxicity, biocompatibility, biodegradability, and magnetic properties. Recent results were expanded upon from the basic cytotoxic tests to evaluate cell proliferation and migration potential. Two cell types were used for the cell proliferation and tracking study: mouse embryonic fibroblast cells (3T3) and human mesenchymal stem cells (hMSCs). Advanced microscopic methods allowed for the precise quantification of the function of both cell types. This study has demonstrated that a dose of nanoparticles lower than 20 µg·cm-2 per area of the dish does not negatively affect the cells' morphology, migration, cytoskeletal function, proliferation, potential for wound healing, and single-cell migration in comparison to standard CellTracker™ Green CMFDA (5-chloromethylfluorescein diacetate). A higher dose of nanoparticles could be a potential risk for cytoskeletal folding and detachment of the cells from the solid extracellular matrix.

• Keywords
• cytotoxicity, fibroblast cells, magnetic nanoparticles, mesenchymal stem cells, single-cell migration, wound healing assay,
• MeSH
• Biomarkers MeSH
• Cell Line MeSH
• Fibroblasts drug effects   metabolism   MeSH
• Immunophenotyping MeSH
• Humans MeSH
• Magnetite Nanoparticles * chemistry   MeSH
• Mesenchymal Stem Cells drug effects   metabolism   MeSH
• Mice MeSH
• Cell Movement drug effects   MeSH
• Cell Proliferation drug effects   MeSH
• Flow Cytometry MeSH
• Reactive Oxygen Species metabolism   MeSH
• Rhodamines chemistry   pharmacology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Biomarkers MeSH
• Magnetite Nanoparticles * MeSH
• Reactive Oxygen Species MeSH
• Rhodamines MeSH

Nano-ecotoxicology is extensively debated and nanomaterial surface reactivity is an emerging topic. Iron oxide nanoparticles are widely applied, with organic or inorganic coatings for stabilizing their suspensions. Surface active maghemite nanoparticles (SAMNs) are the unique example of naked iron oxide displaying high colloidal and structural stability in water and chemical reactivity. The colloidal behavior of SAMNs was studied as a function of the medium salinity and protocols of acute and chronic toxicity on Daphnia magna were consequently adapted. SAMN distribution into the crustacean, intake/depletion rates and swimming performances were evaluated. No sign of toxicity was detected in two model organisms from the first trophic level (P. subcapitata and L. minor). In D. magna, acute EC50 values of SAMN was assessed, while no sub-lethal effects were observed and the accumulation of SAMNs in the gut appeared as the sole cause of mortality. Fast depuration and absence of delayed effects indicated no retention of SAMNs within the organism. In spite of negligible toxicity on D. magna adults, SAMN surface reactivity was responsible of membrane bursting and lethality on embryos. The present study offers a contribution to the nascent knowledge concerning the impact of nanoparticle surface reactivity on biological interfaces.

• MeSH
• Survival Analysis MeSH
• Biological Assay MeSH
• Water Pollutants, Chemical toxicity   MeSH
• Daphnia drug effects   physiology   MeSH
• Embryo, Nonmammalian drug effects   physiology   MeSH
• Metal Nanoparticles toxicity   MeSH
• Locomotion drug effects   MeSH
• Ferric Compounds toxicity   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Water Pollutants, Chemical MeSH
• ferric oxide MeSH Browser
• Ferric Compounds MeSH

In the last few years, magnetically labeled cells have been intensively explored, and non-invasive cell tracking and magnetic manipulation methods have been tested in preclinical studies focused on cell transplantation. For clinical applications, it is desirable to know the intracellular pathway of nanoparticles, which can predict their biocompatibility with cells and the long-term imaging properties of labeled cells. Here, we quantified labeling efficiency, localization, and fluorescence properties of Rhodamine derivatized superparamagnetic maghemite nanoparticles (SAMN-R) in mesenchymal stromal cells (MSC). We investigated the stability of SAMN-R in the intracellular space during a long culture (20 days). Analyses were based on advanced confocal microscopy accompanied by atomic absorption spectroscopy (AAS) and magnetic resonance imaging. SAMN-R displayed excellent cellular uptake (24 h of labeling), and no toxicity of SAMN-R labeling was found. 83% of SAMN-R nanoparticles were localized in lysosomes, only 4.8% were found in mitochondria, and no particles were localized in the nucleus. On the basis of the MSC fluorescence measurement every 6 days, we also quantified the continual decrease of SAMN-R fluorescence in the average single MSC during 18 days. An additional set of analyses showed that the intracellular SAMN-R signal decrease was minimally caused by fluorophore degradation or nanoparticles extraction from the cells, main reason is a cell division. The fluorescence of SAMN-R nanoparticles within the cells was detectable minimally for 20 days. These observations indicate that SAMN-R nanoparticles have a potential for application in transplantation medicine.

• Keywords
• Confocal microscopy, Dual contrast agents, Intracellular fluorescent labels, Iron oxide nanoparticles, Mesenchymal stromal cells, Rhodamine, Stem cell tracking,
• MeSH
• Dextrans metabolism   MeSH
• Spectrometry, Fluorescence MeSH
• Intracellular Space metabolism   MeSH
• Humans MeSH
• Magnetite Nanoparticles chemistry   MeSH
• Mesenchymal Stem Cells cytology   metabolism   MeSH
• Molecular Probes chemistry   metabolism   MeSH
• Molecular Imaging methods   MeSH
• Rhodamines chemistry   MeSH
• Adipose Tissue cytology   MeSH
• Cell Survival MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Dextrans MeSH
• ferumoxides MeSH Browser
• Magnetite Nanoparticles MeSH
• Molecular Probes MeSH
• Rhodamines MeSH