Membrane lipids are the issue
Cells possess a tremendous complexity of lipids and related enzymes and pathways, with more than 4000 different lipid species finely tuned in order to make the most out of their biophysical properties. Membranes are essential in cell physiology, constituting more than 50% by weight and volume of the entire cell and they influence most cellular processes. Therefore cell and membrane lipid content definitively deserve serious consideration. At present, lipid composition and biophysical properties of the membrane network of cultured cells are extremely altered due to current cultivation processes and they do not guarantee the full efficiency to most cell culture processes.