MODULATION OF MEMBRANE CHOLESTEROL CONTENT IN CULTURED LLC-PK1 CELLS

This study was designed to develop a cell culture model to evaluate the effect of cell membrane fluidity on the function of drug carrier proteins. Fluidity of the cell membrane has been linked to its cholesterol content. LLC-PK1 cells were grown as a monolayer and were treated with a BSA-PVP-cholesterol complex in time-dependent studies. The total cholesterol content of the cells was increased 4-fold (from 52 to 200 fmol/mg protein) as a result of this treatment. The cholesterol increase appears to level off at 2 h of treatment. Most of the incorporated cholesterol (77%) was determined to be free cholesterol, the rest being esterified. Membrane fractions of the treated cells were isolated and were determined to carry 88% of the cholesterol content. The studies indicate that it is feasible to deliver cholesterol to cultured epithelial cells and that LLC-PK, cell monolayers can be used as a model for such studies.