Intracellular Fatty Acid Composition Affects Cell Yield, Energy Metabolism and Cell Damage in Agitated Cultures

Continuous passage of cells in serum-free media requires the presence of micronutrients and growth factors to compensate for the lack of serum. Fatty acid supplementation is essential to ensure an adequate composition of the structural lipid components of the cell. We have shown that the unsaturated fatty acids, oleic (C18.1) and linoleic (C18.2) independently enhance cell yield and Mab productivity. The cellular content of the fatty acids gradually increased during continuous culture passage with no evidence of regulatory control. Most of the fatty acid accumulated in the polar lipid fraction and the unsaturated/ saturated fatty acid ratio of all cellular lipid fractions increased significantly. This caused a substantial decrease in the rate of glutamine metabolism and an increase in the rate of glucose metabolism. The changes in energy metabolismwere reversed when the cells were removed from fatty acid-supplemented medium. The most plausible explanation for this effect is an altered rate of transport of glutamine via the cell membrane. An observed change in the phospholipid composition of the membrane also caused a significant protective effect on the cells in agitated cultures. The life-span of fatty acid-loaded cells showed a x3 improvement compared to controls in cultures stirred at high rates of agitation.