Hollow fiber bioreactor
A Hollow fiber bioreactor is a 3 dimensional
Cells are seeded into the EC space of the hollow fiber bioreactor and expand there.
Because thousands of hollow fibers may be packed into a single hollow fiber bioreactor, they increase the surface area of the cartridge considerably. As a result, cells can fill up the EC space to densities >108 cells/ml. However, the cartridge itself takes up a very small volume (oftentimes the volume of a 12-oz soda can). The fact that hollow fiber bioreactors are very small and yet enable incredibly high cell densities has led to their development for both research and commercial applications, including monoclonal antibody and influenza vaccine[1] production. Likewise, because hollow fiber bioreactors use up significantly less medium and growth factors than traditional cell culture methods such as stirred-tank bioreactors, they offer a significant cost savings. Finally, hollow fiber bioreactors are sold as single-use disposables, resulting in significant time savings for laboratory staff and technicians.
History
In 1972, the Richard Knazek
The Knazek group was awarded the patent for hollow fiber bioreactor technology in 1974.[3] Based on this patented technology, companies began building different and larger (commercial) scale hollow fiber bioreactors, with significant development and technological improvement occurring in the late 1980s to early 1990s. By 1990, at least three companies were reported to offer commercially available hollow fiber bioreactors.[4]
One engineering advance included adding a gas exchange cartridge, which enabled better control of system's pH and oxygen levels. Similar to a mammalian lung, the gas exchange cartridge efficiently oxygenated the culture medium, allowing the bioreactor to support higher numbers of cells. Combined with the ability to add or remove CO2 for precise pH control, the limitations commonly associated with large-scale cell culture were eliminated, resulting in densely packed cell cultures that could be maintained for several months.
In addition, control of the fluid dynamics within each hollow fiber bioreactor led to further optimization of the cell culture environment. By alternating the pressure gradient across the hollow fiber membrane, media could flow back and forth between the EC side (cell compartment) and the IC side (hollow fiber lumen). This process, combined with the axial media flow created when media passes down the length of the fibers, optimized the growth environment throughout the entire bioreactor.
This concept is termed EC cycling,
Optimal IC and EC space perfusion rates must be achieved in order to efficiently deliver media nutrients and growth supplements, respectively, and to collect supernatant. During the cell growth phase within these bioreactors, the media feed rate is increased to accommodate the expanding cell population. More specifically, the IC media perfusion rate is increased to provide additional glucose and oxygen to the cells while continually removing metabolic wastes such as lactic acid. When the cell space is completely filled with cells, the media feed rate plateaus, resulting in constant glucose consumption, oxygen uptake and lactate production rates.
Applications
With the introduction of hybridoma technology in 1975,
Hollow fiber bioreactors are used to generate high concentrations of cell-derived products including monoclonal antibodies,
Smaller hollow fiber bioreactors are often used for selection and optimization of
prior to stepping up to larger cell culturing systems. Doing so saves on growth factor costs because a significant portion of the cell culture media does not require the addition of expensive components like fetal bovine serum. Likewise, the smaller hollow fiber bioreactors can be housed in a laboratory incubator just like cell culture plates and flasks.Recently, hollow fiber bioreactors have been tested as novel platforms for the commercial production of high-titer influenza A virus.[9] In this study, both adherent and suspension Madin-Darby Canine Kidney Epithelial Cells (MDCK) were infected with two different strains of influenza: A/PR/8/34 (H1N1), and the pandemic strain A/Mexico/4108/2009 (H1N1). High titers were achieved for both the suspension and adherent strains; furthermore, the hollow fiber bioreactor technology was found comparable in its production capacity to that of other commercial bioreactors on the market, including classic stirred-tank and wave bioreactors (Wave) and ATF perfusion systems.
References
- ^ Hirschel M, Gangemi JD, McSharry J., Myers C. Novel Uses for Hollow Fiber Bioreactors Genetic Engineering News Jun 15, 2011 (Vol. 31, No. 12).
- ^ Knazek RA, Gullino PM, Kohler PO, Dedrick RL. Cell culture on artificial capillaries: an approach to tissue growth in vitro. Science. 1972 Oct 6;178(4056):65-6.
- ^ Cell culture on semi-permeable tubular membranes U.S. Patent US 3821087 A
- ^ Ahern, H. Hollow Fiber Bioreactor Systems Increase Cell Culture Yield The Scientist Magazine (1990)
- ^ Extra-capillary fluid cycling system and method for a cell culture. U.S. Patent US 20130058907 A1
- ^ Kohler, G., and C. Milstein. 1975. Continuous cultures of fused cells secreting antibody of predefined specificity. Nature 256:495.
- ^ Gramer, MJ. Britton TL. Selection and Isolation of Cells for Optimal Growth in Hollow Fiber Bioreactors Hybridoma 2000. 19(5):407-412.
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- ^ Tapia, F. et al. Production of high-titer human influenza A virus with adherent and suspension MDCK cells cultured in a single-use hollow fiber bioreactor Vaccine 32 (2014): 1003-1011.