Influence of environmental medium on fatty acid composition of human cells: Leukocytes and fibroblasts

Abstract

Fibroblasts in culture and leukocytes have been widely used to study fatty acid and lipoprotein cellular metabolism. The present investigations were designed to study the role of nutritional and environmental factors on lipid metabolism in these two types of cells. Leukocytes freshly isolated from human blood and fibroblasts cultured in media enriched in human serum (HS) have relatively similar fatty acid distributions. However, more important differences are observed in fibroblasts cultured in media enriched with HS or with fetal bovine serum (FBS). It is obvious that the quantity and quality of fatty acids are very different in FBS and HS, but intracellular regulation ensures relative homogeneity of saturated (SFA) and monounsaturated fatty acids (MUFA) in the cells, particularly in phospholipids.

The first modifications induced by different media (FBS or HS) are detected on cellular growth; the differences seem to be due more to the fatty acid (FA) quantitative supply than to the FA quality of each culture medium. The major modifications in FA composition induced by different culture media concern the polyunsaturated fatty acids (PUFA) of phospholipids, especially the n−6 family. The intracellular linoleic acid level depends on the level in the medium, but intracellular n−6 metabolite levels depend both on the level in the medium and on the growth state of the cells. The n−3 family seems to be less affected by the quality of the medium in our experiment, and the cells maintain a stable docosahexaenoic acid (22∶6n−3) level. A higher content of the n−3 family in the medium induces a higher level of eicosa-or docosapentaenoic acid, rather than docosahexaenoic acid itself.

Finally, the FA quality of the medium influences the cellular PUFA content but, with a low FA quantitative supply, the FA quality of the medium has less influence on the cellular PUFA quality, and apparently has no effect on the SFA content of phospholipids. Modification of the quantitative supply of the medium and of the quality of the cells (strain and growing state) are more important for the distribution of SFA and MUFA in the neutral lipids of the cells.