Binding and uptake of native and modified low-density lipoproteins by human hepatocytes in primary culture

Authors

  • Dr. Vladimir R. Babaev,

    Corresponding author
    1. Institute of Experimental Cardiology, U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow, U.S.S.R.
    • Institute of Experimental Cardiology, Cardiology Research Center of the U.S.S.R. 3rd Cherepkovskaya Str. 15A, 121552, Moscow, U.S.S.R.
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  • Vladimir A. Kosykh,

    1. Institute of Experimental Cardiology, U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow, U.S.S.R.
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  • Vladimir P. Tsibulsky,

    1. Institute of Experimental Cardiology, U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow, U.S.S.R.
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  • Vadim O. Ivanov,

    1. Institute of Experimental Cardiology, U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow, U.S.S.R.
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  • Vadim S. Repin,

    1. Institute of Experimental Cardiology, U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow, U.S.S.R.
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  • Vladimir N. Smirnov

    1. Institute of Experimental Cardiology, U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow, U.S.S.R.
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Abstract

The binding and uptake of native low-density lipoproteins and malondialdehyde-treated low density lipoproteins by human hepatocytes in primary culture has been analyzed. Experiments with 125I-labeled malondialdehyde-treated low-density lipoproteins showed that cultured liver cells took up and degraded malondialdehyde-treated low-density lipoproteins, but the cell type(s) responsible for this action remain unclear. Immunofluorescent visualization of receptor-bound low-density lipoproteins revealed that low-density lipoprotein binding sites were distributed on the surface of nearly all cells of the culture. Binding sites for malondialdehyde-treated low-density lipoproteins were found in only 5% of the cultured cells, and these cells differed from hepatocytes in shape and size. Cultured hepatocytes internalized and native low-density lipoproteins, but not malondialdehyde-treated low-density lipoproteins, labeled with the fluorescent dye 3′,3′-dioctadecylindocarbocyanine. About 15% of the cells that take up 3′,3′-dioctadecylindocarbocyanine-labeled malondialdehyde-treated low-density lipoproteins could be identified as liver endothelial cells and macrophages, since they internalized formaldehyde-treated human albumin and fluorescent carboxylated microspheres.

Our results indicate that human hepatocytes in primary culture express surface receptors for native low-density lipoproteins but not for modified low-density lipoproteins.

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