Capacity of human monocytes to phagocytose approved iron oxide MR contrast agents in vitro

Stephan Metz, Gabriel Bonaterra, Martina Rudelius, Marcus Settles, Ernst J. Rummeny, Heike E. Daldrup-Link

Research output: Contribution to journalArticlepeer-review

228 Scopus citations


To evaluate the capacity of human monocytes to phagocytose various approved iron oxide based magnetic resonance (MR) contrast agents and to optimize in vitro labeling of these cells. Human monocytes were incubated with two superparamagnetic iron oxide particles (SPIO) as well as two ultrasmall SPIO (USPIO) at varying iron oxide concentrations and incubation times. Iron uptake in monocytes was proven by histology, quantified by atomic emission absorption spectrometry and depicted with T2* weighted fast field echo (FFE) MR images at 1.5 T. Additionally, induction of apoptosis in iron oxide labeled monocytes was determined by YO-PRO-1 staining. Cellular iron uptake was significantly (P<0.01) higher after incubation with SPIO compared with USPIO. For SPIO, the iron oxide uptake was significantly (P<0.01) higher after incubation with the ionic Ferucarbotran as compared with the non-ionic Ferumoxides. Efficient cell labeling was achieved after incubation with Ferucarbotran at concentrations ≧1500 μg Fe/ml and incubation times ≧1 h, resulting in a maximal iron oxide uptake of up to 50 pg Fe/cell without impairment of cell viability. In vitro labeling of human monocytes for MR imaging is most effectively obtained with the approved SPIO Ferucarbotran. Potential subsequent in vivo cell tracking applications comprise, e.g. specific targeting of inflammatory processes.

Original languageEnglish
Pages (from-to)1851-1858
Number of pages8
JournalEuropean Radiology
Issue number10
StatePublished - Oct 2004


  • Cell labeling
  • Iron oxides
  • MR imaging
  • Monocytes
  • Nanoparticles


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