title: Magnetic resonance imaging of pathogenic protozoan parasite Entamoeba histolytica labeled with superparamagnetic iron oxide nanoparticles.
abstract: OBJECTIVE
  The aim of this study was to establish a noninvasive tracking of the pathogenic parasite Entamoeba histolytica (Eh) after superparamagnetic iron oxide (SPIO) labeling by magnetic resonance imaging (MRI) on a single-cell level in vitro and in vivo in a mouse model for amebic liver abscess (ALA).
  
  
  METHODS
  Local institutional review committee on animal care approved all animal experiments. Entamoeba histolytica trophozoites were labeled with SPIO nanoparticles (SPIO-Eh). The uptake of SPIO by Eh was optimized using flow cytometry and visualized by bright field, fluorescence, and transmission electron microscopy. The viability of SPIO-Eh was assessed in vitro by determination of growth and ingestion rate of red blood cells. Migration of SPIO-Eh was proven by in vitro MRI in a preclinical 7 T MRI system using continually repeated MRI scans. In vivo distribution of SPIO-Eh within the mouse liver was assessed qualitatively and quantitatively by serial respiration-triggered T2*-weighted MRI, T2-weighted MRI, and R2* MR relaxometry up to 5 days after injection and correlated with immunohistology of the liver sections after removal.
  
  
  RESULTS
  Entamoeba histolytica can be efficiently labeled with SPIO without influence on parasite growth rate or phagocytic capacity. In vitro dynamic MRI allowed real-time migration monitoring and determination of velocity of single SPIO-Eh. In vivo SPIO-Eh showed signal decrease in T2*-weighted and increase of R2* in ALA formations. Motility of SPIO-Eh was necessary to induce ALA formations.
  
  
  CONCLUSIONS
  The present study demonstrates the feasibility of an efficient magnetic labeling and a noninvasive in vitro and in vivo MR tracking of the pathogenic protozoan Eh in a mouse model for ALA, thus representing in future a noninvasive imaging tool to study parasite, as well as on host-specific pathomechanisms.
authors.affiliation: From the *Diagnostic and Interventional Radiology Department and Clinic, University Medical Center Hamburg-Eppendorf; and †Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Ernst
authors.forename: Helena
authors.initials: H
authors.lastname: Fehling
authors.forename: Hannah
authors.initials: H
authors.lastname: Bernin
authors.forename: Mareen D
authors.initials: MD
authors.lastname: Zaruba
authors.forename: Iris
authors.initials: I
authors.lastname: Bruchhaus
authors.forename: Gerhard
authors.initials: G
authors.lastname: Adam
authors.forename: Harald
authors.initials: H
authors.lastname: Ittrich
authors.forename: Hannelore
authors.initials: H
authors.lastname: Lotter
mesh_terms: D000818:Animals; D058948:Cell Tracking / Q000379:methods*; D003287:Contrast Media; D004195:Disease Models, Animal; D004748:Entamoeba histolytica; D004749:Entamoebiasis / Q000175:diagnosis*; D005240:Feasibility Studies; D005290:Ferric Compounds; D008099:Liver / Q000469:parasitology; D008109:Liver Diseases, Parasitic / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D053768:Metal Nanoparticles; D051379:Mice; D015203:Reproducibility of Results; D013194:Staining and Labeling / Q000379:methods
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide