MODULATION OF MR-VISIBLE MOBILE LIPID-LEVELS BY CELL-CULTURE CONDITIONS AND CORRELATIONS WITH CHEMOTACTIC RESPONSE

A transformed murine fibroblast cell line has been used to assess whic h criteria govern the appearance of a lipid pool that is mobile on the MR time scale. A high-resolution proton MR signal arising from neutra l lipids, including triglyceride and cholesteryl esters, has previousl y been associated with membrane events in stimulated, transformed and malignant cells. We report that the attenuation of cellular proliferat ion by confluence or low pH caused significant increases in MR-visible lipid and that the lipid signal could be amplified at high density by the removal of serum. A significant decrease in chemotactic response accompanied the culture of cells at high density, but chemotactic resp onse was not generally linked to alteration of the lipid signal. The a ppearance of the signal was also not correlated with the proportion of cells in any phase of the cell cycle. Significant changes in the MR-v isible pools of the lipid metabolites choline, phosphocholine and glyc erophosphocholine were measured under the culture conditions employed with 2D MRS and suggest that MR-visible lipid may arise from the catab olism of phospholipids. (C) 1996 Wiley-Liss, Inc.