Serum and growth factors in cell culture media--an introductory review

Amongst this bewildering array of growth factors, serum replacements and serum-free media is there a system which works well for most cell types used in biotechnology? If so is there a short-cut for novices in the field to be able quickly to select the right formulation. I hope the following discussion will enable those with experience in this field to share that experience so that we can get an indication of which compound works for which cell under which conditions. Also the cost in both yield and monetary terms needs to be kept in perspective as one option is to produce these very expensive factors from genetically engineered bacteria. Discussion points should include the question of why so many medium formulations still include serum at 0.1 or 0.5% i.e. what does this small quantity of serum provide and does it mean that in fact we cannot have a completely protein-free media to achieve optimal growth? In which case, what is the minimal acceptable level? An adaptation procedure to low-serum media is accepted as essential but in fact the time-scale for this varies enormously from laboratory to laboratory and the question must be asked "is this based on quantitative or empirical investigation"? I hope the following panel discussion will answer these questions as the correct use of growth factors is of vital importance to the future development of cell product technology. It is probably true to say that with the correct blend of these compounds all cell types can be grown in culture as successfully as the ubiquitous fibroblast.