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Radiology. 2001 Oct;221(1):244-50.

Human transferrin receptor gene as a marker gene for MR imaging.

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Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Bldg 149, 13th St, Rm 5419, Charlestown, MA 02129, USA.



To quantitate and characterize the expression of an engineered human transferrin receptor (ETR) as a marker gene by using magnetic resonance (MR) imaging.


Rat gliosarcoma 9L cells stably expressing ETR (ETR+) were used, with nontransfected (ETR-) cells serving as controls. A conjugate of transferrin and monocrystalline iron oxide (Tf-MION) nanoparticles was synthesized to probe for the activity of ETR. Accumulation of Tf-MION was examined by using cell internalization in culture and MR (n = 6) and nuclear (n = 4) imaging in a mouse model with ETR+ and ETR- tumors implanted in the opposite flanks. Autoradiographic and histopathologic results were correlated with MR findings.


Tf-MION was internalized by ETR+ cells at 37 degrees C but not at 4 degrees C. Rhodamine-labeled Tf-MION and fluorescein-labeled antibody to ETR colocalized in small vesicle-like structures in the cytoplasm. Both findings were consistent with accumulation by the receptor-mediated endocytosis mechanism of ETR. Compared with ETR- tumors, ETR+ tumors accumulated more Tf-MION and had higher signal intensity on T1-weighted MR images and lower signal intensity on T2-weighted images. Autoradiographic findings showed a spatial correlation between MR signal intensity and TF-MION accumulation.


ETR+ tumors internalize the MR imaging probe through the action of transferrin receptor in amounts that can be detected with MR imaging.

[Indexed for MEDLINE]

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