LOCALIZATION OF UNESTERIFIED CHOLESTEROL IN HUMAN ATHEROSCLEROTIC LESIONS - DEMONSTRATION OF FILIPIN-POSITIVE, OIL-RED-O-NEGATIVE PARTICLES

  • 1 January 1984
    • journal article
    • research article
    • Vol. 114  (2) , 201-208
Abstract
Both unesterified and esterified cholesterol accumulate in human atherosclerotic lesions. Whereas previous studies have established that esterified cholesterol deposits intra- and extracellularly, less is known concerning the distribution of lesion unesterified cholesterol. The objective of this study was to establish the location, and in what structures, unesterified cholesterol accumulates in lesions. The fluorescent probe filipin was used to detect unesterified cholesterol. In addition, the lipid-soluble dye oil red O (which does not stain unesterified cholesterol) was used to stain hydrophobic lipids, including esterified cholesterol). Filipin staining occurred in association with 3 extracellular structures: spherical particles, elongated crystals, and granular or amorphous Ca deposits. These structures were not stained by oil red O. Filipin-stained particles sometimes accmulated within cells which did not contain any oil-red-O-stained lipid. Interestingly, extracellular filipin-stained particles occurred in loci separate from extracellular oil-red-O-stained particles. Accumulation of unesterified and esterified cholesterol occurs within many diverse structures in atherosclerotic lesions. Extracellular filipin-stained particles constituted a significant component of accumulated cholesterol. These cholesterol-rich particles have not been previously observed because they are not stained by lipid-soluble dyes such as oil red O.