Abstract:
RATIONALE AND OBJECTIVES:Target-specific magnetic resonance (MR) contrast agents are being developed to improve the accuracy of MR imaging. The purpose of this study was to determine the mechanism of cell uptake, and modes of intracellular trafficking of a prototypical iron oxide label (RMA) used in the synthesis of some target-specific MR contrast agents. METHODS:The prototypical agent (RMA) consisted of a dextran-coated monocrystalline iron oxide that was modified with rhodamine (fluorescent label) and opsonized with albumin. Fluorescence microscopy was performed in a phagocytic C6 cell line and in murine bone marrow macrophages. Immunohistochemistry against lysosomal markers was used to confirm the intracellular location of the label. RESULTS:RMA was identified inside cells after incubation at concentrations as low as 4.0 x 10(-10) M Fe, typically observed with receptor mediated endocytosis and several orders of magnitude lower than that expected with fluid phase pinocytosis. Cell uptake could be inhibited by excess protein but not by dextran. RMA localized initially to tubular and to round intracellular organelles and co-localized with an antibody against a murine lysosomal glycoprotein antibodies (LGP-A) in macrophages. Three days after incubation, RMA was concentrated in perinuclear vesicles, which most likely represent terminal lysosomes where final breakdown appears to occur. CONCLUSIONS:The mechanism of cellular uptake of a prototypical opsonized iron oxide label is consistent with receptor-mediated endocytosis. Immediately after cell contact, RMA localizes to the lysosomal compartment and at long time points reside in vesicles that by morphology and distribution appear to be terminal lysosomes. Iron oxides therefore demonstrate metabolism via the lysosomal pathway.
journal_name
Invest Radioljournal_title
Investigative radiologyauthors
Schulze E,Ferrucci JT Jr,Poss K,Lapointe L,Bogdanova A,Weissleder Rdoi
10.1097/00004424-199510000-00006subject
Has Abstractpub_date
1995-10-01 00:00:00pages
604-10issue
10eissn
0020-9996issn
1536-0210journal_volume
30pub_type
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journal_title:Investigative radiology
pub_type: 杂志文章
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journal_title:Investigative radiology
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journal_title:Investigative radiology
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doi:10.1097/00004424-199808000-00001
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更新日期:1986-04-01 00:00:00
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更新日期:2014-06-01 00:00:00
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journal_title:Investigative radiology
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journal_title:Investigative radiology
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journal_title:Investigative radiology
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journal_title:Investigative radiology
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