One Step Sterile Harvesting of Mammalian Cell cultures in the lab

Bio-pharmaceuticals R&Ds are working with mammalian cell expression systems for developing mAbs and other therapeutic proteins. Scientists today are using increasingly smaller culture volumes grown in 10ml to 15ml micro bioreactor formats or even smaller volumes in 24 to 48 plate systems for clone and media optimization, cell line selection, small scale perfusion mimic and early process optimization. In these applications multiple cell harvests need to be clarified to remove cells and debris before the critical metabolite analysis/ chromatography steps. Conventional methods for clarification of such small volumes (few mL) are centrifugation followed by 0.2µm membrane filtration.

However centrifugation is a time consuming, cumbersome process and may also result in shearing of cells resulting in increased cell debris, cell organelles and intracellular proteins in the supernatant. The conventional syringe filter, although used for final filtration of the supernatant does not offer an efficient solution in terms of throughputs.’

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Effect of Sterilizing Filters on Process Economics in Bio-pharmaceuticals

Bio-pharmaceutical manufacturing is a complex, multistep process involving a very wide variety of process streams under different process conditions at different steps. These process streams include cell culture media, media additives, growth regulators in the upstream and post centrifuge cell harvest supernatants, post viral inactivation process intermediates, buffers, and high value product concentrates in the downstream. Filtration and purification of such a wide spectrum of process streams, to achieve different process objectives at each process step, is quite a challenge for the process owner. Also the increasingly competitive market conditions, due to the introduction of biosimilars, further escalates the demand for higher standards of filter performance, with respect to economy, safety, and impact on final product quality.

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Clarification of Cell Harvests from Micro Bioreactors

Lab scale clarification of cell harvests is increasingly becoming more challenging as the standard clarification techniques such as centrifugation, tangential flow filtration (TFF) and depth filtration are not easily adaptable to micro bioreactors which require multiple processing of small volumes of cell harvests, typically 50 mL. Centrifugation may damage the shear sensitive mammalian cells and not only release undesirable intra cellular proteins and DNA into the broth but also submicron particles which are difficult to remove. TFF systems require long setup time and are prohibitively expensive for lab scale volumes. Depth filters on the other hand necessitate monitoring of differential pressures and sometimes allow passage of cell debris and other fine particulate which tend to choke the downstream 0.2µm sterilizing grade filters. Also, these require large pre-use flush volumes to remove inherent extractables owing to their cellulosic matrix with inorganic filter aids such as diatomaceous earth or perlite. Continue reading “Clarification of Cell Harvests from Micro Bioreactors”

How to clarify cell harvests without centrifugation in the lab?

Bio-pharmaceutical industry is involved in development and manufacture of therapeutic drug proteins and monoclonal antibiotics using mammalian cell expression systems, a vital and constantly developing technology.

Cultured cells from mammalian cell expression systems, ranging from a few mL to a few liters in shaker flasks, cell factories and small bioreactors to thousands of liters in large bioreactors, deliver extracellular protein and need to be harvested and clarified for downstream processing to obtain the purified protein of interest. Cell culture clarification is necessary to protect highly sensitive and expensive downstream processes such as diafiltration, ultrafiltration and protein chromatography, and is a challenging task as it contains whole cells, cell debris from dead cells as well a whole gamut of proteins from the cellular activity.

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