High-density lipoprotein and cerebral endothelial cells in vitro: interactions and transport.
Primary cultures of bovine cerebral endothelial cells were used as an in vitro model for the blood-brain barrier to study the transport and interactions of high-density lipoprotein (HDL) across monolayers of these cells. Transport of 125I-apoE free HDL across a monolayer of bovine cerebral endothelial cells occurred in a linear fashion up to a concentration of 70 micrograms/mL, suggesting paracellular transport of HDL. Bovine cerebral endothelial cells possess a high affinity binding site for HDL with a mean dissociation constant (KD) of 10.8 +/- 2.6 micrograms/mL (N = 4). Maximal binding of apoE free HDL to cerebral endothelial cells proved to be temperature-dependent: at 4 degrees a Bmax value of 42 +/- 9.3 ng/mg cell protein was found, while at 37 degrees this value was 177 +/- 70.4 ng/mg cell protein. Cell association of 125I-HDL could be effectively displaced by HDL, not by low-density lipoprotein or acetylated low-density lipoprotein, and association was not coupled to degradation. The in vitro blood-brain barrier cell system possesses high affinity binding sites for HDL, which are probably not involved in the transport of HDL across cerebral endothelial cells.
de Vries
H E
HE
Division of Pharmacology, Leiden/Amsterdam Center for Drug Research, University of Leiden, Sylvius Laboratories, The Netherlands.
Breedveld
B
B
Kuiper
J
J
de Boer
A G
AG
Van Berkel
T J
TJ
Breimer
D D
DD
D000818:Animals; D001057:Apolipoproteins E / Q000378:metabolism; D001692:Biological Transport; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004727:Endothelium / Q000378:metabolism; D007457:Iodine Radioisotopes; D008075:Lipoproteins, HDL / Q000378:metabolism*; D013696:Temperature
D001057:Apolipoproteins E; D007457:Iodine Radioisotopes; D008075:Lipoproteins, HDL