Real-Time Analysis of Magnetic Hyperthermia Experiments on Living Cells under a Confocal Microscope

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2015-05, Vol.11 (20), p.2437-2445
• Main Authors: Connord, Vincent, Clerc, Pascal, Hallali, Nicolas, El Hajj Diab, Darine, Fourmy, Daniel, Gigoux, Véronique, Carrey, Julian
• Format: Article
• Language: English
• Subjects: cell death; Cell Survival; Computer Systems; confocal microscopy; Endocytosis; Fever; Gene expression; Humans; Hyperthermia, Induced; Intracellular Space - metabolism; Lysosomes - metabolism; Magnetic Fields; magnetic hyperthermia; magnetic nanoparticles; Microscopy, Confocal - methods; Miniaturization; Nanoparticles; Nanotechnology; Permeability; Physics; reactive oxygen species; Reactive Oxygen Species - metabolism
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201402669

Combining high‐frequency alternating magnetic fields (AMF) and magnetic nanoparticles (MNPs) is an efficient way to induce biological responses through several approaches: magnetic hyperthermia, drug release, controls of gene expression and neurons, or activation of chemical reactions. So far, these experiments cannot be analyzed in real‐time during the AMF application. A miniaturized electromagnet fitting under a confocal microscope is built, which produces an AMF of frequency and amplitude similar to the ones used in magnetic hyperthermia. AMF application induces massive damages to tumoral cells having incorporated nanoparticles into their lysosomes without affecting the others. Using this setup, real‐time analyses of molecular events occurring during AMF application are performed. Lysosome membrane permeabilization and reactive oxygen species production are detected after only 30 min of AMF application, demonstrating they occur at an early stage in the cascade of events leading eventually to cell death. Additionally, lysosomes self‐assembling into needle‐shaped organization under the influence of AMF is observed in real‐time. This experimental approach will permit to get a deeper insight into the physical, molecular, and biological process occurring in several innovative techniques used in nanomedecine based on the combined use of MNPs and high‐frequency magnetic fields. A miniaturized electromagnet makes possible the generation of a high‐frequency magnetic field under a confocal microscope. Several physical and biological events occurring in cells containing magnetic nanoparticles and submitted to such a field are observed and quantified in real‐time: cell damages, reactive oxygen species production, lysosome permeabilization, and nanoparticles self‐assembling.