Cellular magnetic resonance with iron oxide nanoparticles: long-term persistence of SPIO signal in the CNS after transplanted cell death

Nanomedicine (Lond). 2014 Jul;9(10):1457-74. doi: 10.2217/nnm.14.84. Epub 2014 May 13.


Aim: To study the specificity of cellular MRI based on superparamagnetic iron oxide particles (SPIOs), especially within the CNS.

Materials & methods: A microglial cell line was engineered for the expression of a suicide gene, the receptor of diphtheria toxin (DT), and two reporter genes, green fluorescent protein and luciferase, in order to induce, in a controlled manner, cell death and test it through bioluminescence. SPIO-labeled DT-sensitive and control DT-insensitive cells were transplanted into the brains of mice, which underwent serial MRI and bioluminescence studies before and up to 90 days after DT-induced cell death.

Results: No variations in SPIO signal voids were detected along longitudinal monitoring in brain hemispheres transplanted with DT-sensitive cells. Ex vivo analyses showed persistence of iron nanoparticle deposits at transplantation sites.

Conclusion: Due to the long-term persistence of signal after transplanted cell death, caution is advised when SPIOs are employed for cell tracking.

Keywords: cell death; cellular MRI; diphtheria toxin; microglial cell; specificity; superparamagnetic iron oxide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Brain / cytology*
  • Brain / surgery
  • Cell Line
  • Cell Tracking / methods*
  • Dextrans*
  • Female
  • Longitudinal Studies
  • Magnetic Resonance Imaging / methods*
  • Magnetite Nanoparticles*
  • Mice
  • Mice, Nude
  • Microglia / cytology*
  • Microglia / transplantation*


  • Dextrans
  • Magnetite Nanoparticles
  • ferumoxtran-10