title: Controlled cell death by magnetic hyperthermia: effects of exposure time, field amplitude, and nanoparticle concentration.
abstract: OBJECTIVE
  To investigate the effects of alternating magnetic fields (AMF) on the death rate of dendritic cells (DCs) loaded with magnetic nanoparticles (MNPs) as heating agents. AMF exposure time and amplitude as well as the MNPs concentration were screened to assess the best conditions for a controlled field-induced cell death.
  
  
  METHODS
  Human-monocyte-derived DCs were co-incubated with dextran-coated MNPs. The cells were exposed to AMF (f = 260 kHz; 0 < H(0) < 12.7 kA/m) for intervals from 5 to 15 min. Morphology changes were assessed by scanning electron microscopy. Cell viability was measured by Trypan blue and fluorescence-activated cell sorting (FACS) using Annexin-propidium iodide markers.
  
  
  RESULTS
  We were able to control the DCs viability by a proper choice AMF amplitude and exposure time, depending on the amount of MNPs uploaded. About 20% of cells showed Annexin-negative/PI-positive staining after 5-10 min of AMF exposure.
  
  
  CONCLUSIONS
  Controlled cell death of MNP-loaded DCs can be obtained by adequate tuning of the physical AMF parameters and MNPs concentration. Necrotic-like populations were observed after exposure times as short as 10 min, suggesting a fast underlying mechanism for cell death. Power absorption by the MNPs might locally disrupt endosomic membranes, thus provoking irreversible cell damage.
authors.affiliation: Instituto de Nanociencia de Aragón, University of Zaragoza, Mariano Esquillor, 50018 Zaragoza, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Asín
authors.forename: M R
authors.initials: MR
authors.lastname: Ibarra
authors.forename: A
authors.initials: A
authors.lastname: Tres
authors.forename: G F
authors.initials: GF
authors.lastname: Goya
mesh_terms: D016923:Cell Death; D002470:Cell Survival; D003713:Dendritic Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D005290:Ferric Compounds / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D006979:Hyperthermia, Induced; D060526:Magnetic Fields; D008280:Magnetics; D053768:Metal Nanoparticles; D008855:Microscopy, Electron, Scanning; D013997:Time Factors
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide