The SBI Approach
Production scale growth of mammalian cells or microbial cells is commonly performed by pharmaceutical companies in very large, primarily stainless steel, stirred tank reactors for the purpose of producing biopharmaceuticals. For many years, laboratory bench-scale process development and process optimization has been carried out in scalable bioreactors that have customarily ranged in size from 1 liter volumes to 5 liter volumes. Laboratory bench-scale bioprocessing, while an effective alternative for process development and optimization, is still somewhat labor intensive and time consuming if you consider the sterility requirements as well as the reactor set-up time when the need is for a multiplicity of parallel experiments. Since the year 2000, there has been explosive growth in the pursuit of new biopharmaceuticals. Highthroughput bioprocessing is a promising technique for the development and optimization of mammalian and microbial cultures. There is a demand to significantly reduce time and material and labor costs by using mini-sized reaction vessels without losing the ability of scale-up or process applicability in predicting the much larger production scale reactions. There is also the desire to greatly reduce hands-on time for experiment set-up and the time for replication of a multiplicity of parallel reactions necessary to prove process engineering scale-up calculations.
Emerging biopharmaceuticals are creating huge and ever-growing needs for faster and faster bioprocess development and optimization. Mammalian cells, used for bioprocessing, have the advantage of being able to produce complex, bioactive molecules. However, mammalian cells grow and express proteins at approximately 5% of the rate of E. coli cells. Mammalian cells also require expensive growth media. The use of mammalian cells requires higher capital and labor costs. There is an unfulfilled demand for faster and less costly high throughput mammalian culture methods for bioprocess development and bioprocess optimization. The most promising way to meet that demand is for miniaturization of the hardware and reaction vessels required for mammalian cultures and for a dramatic increase in the number of parallel reaction vessels set up for simultaneous operation. Small volume bioreactor vessels, of the approximate size of 30 ml up to 100 ml in reactor volume, with appropriate and effective stirring and gas transfer characteristics, as well as appropriate process control characteristics, have been shown to have the capability of extrapolating to and the verification of the engineering calculations for direct scale-up to production sized bioprocess reaction vessels of 100 liters or greater.
Bioprocessing has become completely embedded in our lives today. Without bioprocessing, millions and millions would starve and we’d drown in our own waste. Bacteria, enzymes, proteins and various other biological materials are processed in manufacturing facilities. Bioprocessing is responsible for the production of many healthcare and well-being products including insulin, growth hormones, replacement hormones, alphainterferon, monoclonal antibodies, hepatitis vaccine, erythropoietin, vitamins, chemotherapeutics, hyaluronic acid, laboratory diagnostics materials i.e. tissue plasminogen activator, cardiac enzyme tests, liver function tests, cancer screening tests, thyroid screening tests and the lists go on and on. Protein characterization, genetic mapping, DNA analysis, and cell and tissue typing, are but a few of the diagnostic developments that have arrived in the last half of the twentieth century.
Biological waste treatment is now the norm for cleansing water, removal of gas and clearing of odors. Oils and fats are processed using bioprocess methods. Biodegradable plastics are possible today because of bioprocessing. Agricultural plants can be engineered to synthesize therapeutic proteins. Bioengineering has produced crops that can fight off disease and crops with higher protein content. Perhaps the fastest growing technology today has to do with the discovery of new therapeutics and medicines as a result of bioprocess technology. New treatments for anemia and leukemia are produced with biopharmaceutical processing. Customized cancer treatments are starting to emerge as a result of biotechnology.
It is becoming, at the least, increasingly more difficult and, at the worst, impossible to keep up with the demands for process development with the development and optimization systems in place today. Process development, currently and for the most part, is done in volumes of 1 to 5 liters because the scale-up characteristics are well documented. It has been done that way for thirty years or more. The increasing costs of continuing with current methods for process development and process optimization are starting to outstrip our ability to fund new process development. It has become imperative that we reduce the size of the reaction vessels to reduce the costs of materials required for the quantity of multiple and parallel process experiments necessary for process development. It has become imperative to reduce the operating hardware clean-up time, sterilization requirements, and turn-around time. And, increasing labor costs have outpaced the costs of materials disposability. All of these things contribute to the attractiveness of sterile, disposable, miniature sized reaction vessels.
The utility of the CellStation® mini-reactor system resides in its ability to mimic the cell growth characteristics of large-scale stirred tank reactors. The utility further lies in the ability of the reaction vessel of this unique product to significantly reduce the volume of nutrient media required to observe cell growth rates in parallel reactions and the time and labor savings attendant to the disposability of the vessel of this invention thereby eliminating the need for disassembly, cleaning, reassembly, sterilization and finally set-up of the sterilized vessel for re-use. The uniqueness of this invention lies within the function of a very small volume bioreactor vessel that cooperates with a process control module that responds quickly, in real-time, to adjust to the changing metabolic demands of the cell growth process, independently in each individual reaction vessel, and in the immediate and automatic corrections in the process parameters, independently in each individual reaction vessel, dictated by the preprogramming of the operating software.