LIPID-COMPOSITION OF CULTURED ENDOTHELIAL-CELLS IN RELATION TO THEIR GROWTH

Human endothelial cells in culture were examined in different growth c onditions. The human endothelial cell line, EA.hy 926 cell line, was u sed and cells were studied either in exponential growth phase, at conf luence, or growth-arrested by serum deprivation. Phospholipids were se parated and analyzed by high-performance thin-layer chromatography, an d their fatty acids were quantified by gas-liquid chromatography. No s ignificant differences in the phospholipid distributions were found be tween exponentially growing and confluent endothelial cells in which p hosphatidylcholine (PC) represented the major phospholipid. In compari son, serum-deprived cells exhibited higher proportions of sphingomyeli n and lower content of PC. We also found that among the total lipids, cholesterol level for dividing endothelial cells was lower than for ce lls growth-arrested either by serum deprivation or by contact inhibiti on at confluence. The global fatty acid distribution was not affected by the growth conditions. Thus, oleate (18:1n-9 and 18:1n-7), palmitat e (C-16:0), and stearate (C-18:0) Were the main components of endothel ial cell membranes. However, the fatty acid distributions obtained fro m each phospholipid species differed with the growth status. Altogethe r, the data indicated that subtle modulations of endothelial cell meta bolism appear upon cell growth. The resulting membrane-dependent cellu lar functions such as cholesterol transport and receptor activities ca n be expected to be relevant for lipid trafficking within the vessel w all in vitro and in vivo.