Complex Versus Chemically Defined
There are two areas that are generating the most interest these days. The first is the elimination of complex and undefined
media components and their replacement with known chemical composition and the second is the replacement of animal-derived
materials with non-animal–derived materials. With the exception of some processes, most non-animal–derived materials and chemically
defined media equivalents do not meet the same performance criteria as their counterparts by not meeting the specific nutrient
requirements of individual cell lines. Keeping this in mind, the most effective approach to the development of chemically
defined media is to design the media formulation based on the specific nutritional needs of the cell line.7 In today's biopharmaceutical industry, the following criteria significantly dictate process development:
- primary raw materials will meet regulatory requirements
- they will consist of non-animal–derived components
- the process will be high yielding
- it will be scalable
- it will be reproducible
- it will meet economic criteria.
A shift toward chemically defined media increases process cost and economically this must be offset against improvement elsewhere
in the process, whether this be increased titers or simpler purification requirements.
Chemical definition at the laboratory scale is relatively inexpensive and can be vital for the investigation of many factors
including physiological and biochemical assessment of growth, but work at this scale must be centered on the eventual scaled-up
The economic implications imposed on a process following the switch to a chemically defined medium are somewhat offset by
reductions in raw material variability and reduced controlled and uncontrolled process deviations. This in turn favors batch-to-batch
consistency in products and permits simpler purification strategies. Process predictability has become important for biopharmaceutical
manufacturers, and using components of a defined chemical composition can reduce process fluctuations, improve overall process
control, and enhance operability.
Furthermore, it is far easier to optimize a process of known biochemical composition than to base development on empirical
methods. Most mathematical Design of Experiments (DoE) based on raw material evaluation give more significant and meaningful
results if used on chemically defined compositions and can be beneficial in the switch from complex to defined. The advantages
and disadvantages of replacing complex media with chemically defined media are listed in Table 1.
Table 1. A comparison between the major advantages and disadvantages of complex and chemically defined media