Linoleic acid improves the robustness of cells in agitated cultures

The murine hybridoma (CC9C10) was subjected to high shear rates in a spinne r flask to determine the effect of various culture additives on cell surviv al. At 500 rpm, the half-life of the viable cell concentration in a low pro tein serum-free medium was 50 min. Both bovine serum albumin and Pluronic F -68 had a significant effect in protecting cells under these conditions. Th e effects of the two supplements were additive, so that in the presence of both supplements there was minimal cell damage at 500 rpm. The survival rat e of cells grown in media supplemented with linoleic acid improved signific antly under high stirring rates. Cells grown for one passage in 50 mu M lin oleic acid and stirred at 500 rpm had a significantly higher survival rate than control cells. For cells grown over 5 passages in 25 mu M linoleic aci d, the survival rate at 470 rpm was x 3 greater than that determined for co ntrol cells. This difference gradually decreased at higher stirring rates u p to 610 rpm when the half-life of the viable cell population was reduced t o similar to 10 min. Supplementation of cultures with linoleic acid has pre viously been shown to result in incorporation into all three cellular lipid fractions - polar, non-polar and free fatty acid (Butler et al., 1997). Ou r explanation for the increased survivability of the cells at high agitatio n rates in the presence of linoleic acid is that the structural lipid compo nents of the cell including the outer membrane attained a higher unsaturate d/saturated ratio which was more robust than that of control cells.