Altered ultrastructural morphology of self-aggregated low density lipoproteins: coalescence of lipid domains forming droplets and vesicles.

Published

Journal Article

Lipid droplets and vesicles can presumably be formed directly from lipoproteins in the extracellular space in atherosclerosis, but an in vitro demonstration of the phenomenon in the absence of cellular pathways has been lacking. Low density lipoproteins (LDL) are known to undergo self-aggregation after brief vortexing in vitro. In the present study, LDL aggregates were examined by electron microscopy, using new mordant techniques for lipid visualization, and by chemical analysis. Aggregation of LDL by vortexing is regularly accompanied by the formation of comparatively large lipid droplets (up to 600 nm diameter) and vesicles. Aggregates containing droplets and vesicles were formed after as little as 5 sec of vortexing, and LDL protein and cholesteryl ester were almost completely (95%) incorporated into aggregates after 4 min vortexing. Substantial fractions of phospholipid and unesterified cholesterol from the original LDL remained in solution even after 4 min vortexing, forming large multilamellar vesicles that did not adhere to the aggregated material. Spontaneous aggregates retrieved from LDL solutions after prolonged storage were also examined by electron microscopy, revealing similar lipid droplets and vesicles. The ultrastructural appearance of LDL aggregated in vitro is remarkably similar to the appearance of extracellular lipid deposits in atherosclerosis, lending credence to the hypothesis of direct extracellular formation of these deposits from lipoproteins.

Full Text

Duke Authors

Cited Authors

  • Guyton, JR; Klemp, KF; Mims, MP

Published Date

  • June 1991

Published In

Volume / Issue

  • 32 / 6

Start / End Page

  • 953 - 962

PubMed ID

  • 1940627

Pubmed Central ID

  • 1940627

Electronic International Standard Serial Number (EISSN)

  • 1539-7262

International Standard Serial Number (ISSN)

  • 0022-2275

Language

  • eng