Adaptation of tissue culture cells to a serum-free medium

On-demand serum-free media formulations for human hematopoietic cell expansion using a high dimensional search algorithm

Substitution of serum and other clinically incompatible reagents is requisite for controlling product quality in a therapeutic cell manufacturing process. However, substitution with chemically defined compounds creates a complex, large-scale optimization problem due to the large number of possible factors and dose levels, making conventional process optimization methods ineffective. We present a framework for high-dimensional optimization of serum-free formulations for the expansion of human hematopoietic cells. Our model-free approach utilizes evolutionary computing principles to drive an experiment-based feedback control platform. We validate this method by optimizing serum-free formulations for first, TF-1 cells and second, primary T-cells. For each cell type, we successfully identify a set of serum-free formulations that support cell expansions similar to the serum-containing conditions commonly used to culture these cells, by experimentally testing less than 1 × 10-5 % of the total search space. We also demonstrate how this iterative search process can provide insights into factor interactions that contribute to supporting cell expansion.

Influence of Primatone RL supplementation on sialylation of recombinant human interferon-gamma produced by Chinese hamster ovary cell culture using serum-free media

Although serum-free media have been widely used in mammalian cell culture for therapeutic protein production, the effects of serum-substitutes on product quality have not been extensively examined. This study observed an adverse effect of Primatone RL, an animal tissue hydrolysate commonly used as a serum-substitute to promote cell growth, on sialylation of interferon-gamma (IFN-gamma) derived from Chinese hamster ovary (CHO) cell culture in both batch and fed-batch modes. In batch cultures, decreased sialylation was observed at each of the glycosylation sites (i.e., Asn(25) and Asn(97)) of IFN-gamma with the use of elevated concentrations of the peptone. Although poorest sialylation was obtained with the use of a growth-inhibiting concentration of Primatone RL, diminished sialylation was observed at the optimal peptone concentration for cell growth and product yield. Since incubation of the product in Primatone RL-supplemented acellular medium did not result in decreased sialylation, the negative effect of Primatone RL could not be attributed to extracellular desialylation of IFN-gamma by components of the peptone. In the fed-batch mode, a culture utilizing a serum-free feeding medium supplemented with Primatone RL demonstrated poorer sialylation than a similar culture not fed the peptone. The results of both the batch and fed-batch experiments indicate that the adverse effect of the peptone was not due solely to ammonia accumulation. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 353-360, 1997.

Optimization of chemically defined cell culture media--replacing fetal bovine serum in mammalian in vitro methods

Quality assurance is becoming increasingly important. Good laboratory practice (GLP) and good manufacturing practice (GMP) are now established standards. The biomedical field aims at an increasing reliance on the use of in vitro methods. Cell and tissue culture methods are generally fast, cheap, reproducible and reduce the use of experimental animals. Good cell culture practice (GCCP) is an attempt to develop a common standard for in vitro methods. The implementation of the use of chemically defined media is part of the GCCP. This will decrease the dependence on animal serum, a supplement with an undefined and variable composition. Defined media supplements are commercially available for some cell types. However, information on the formulation by the companies is often limited and such supplements can therefore not be regarded as completely defined. The development of defined media is difficult and often takes place in isolation. A workshop was organised in 2009 in Copenhagen to discuss strategies to improve the development and use of serum-free defined media. In this report, the results from the meeting are discussed and the formulation of a basic serum-free medium is suggested. Furthermore, recommendations are provided to improve information exchange on newly developed serum-free media.

Serum fractionation and the effects of bovine serum fractions on human cells grown in a chemically defined medium

Serum has been fractionated by curtain electrophoresis using carboxymethyl cellulose dissolved in sodium bicarbonate electrolyte. Various fractions were produced from bovine serum and added to replicate cultures of Chang's endoepithelial cells and HeLa cells grown in a chemically defined medium. The effects of each of the various fractions on the appearance of the cultures and on cell multiplication were studied. Three different fractions were obtained and two were subjected to further purification. One fraction associated with albumin promoted survival, attachment, and flattening as well as cell multiplication. A second fraction associated with the alpha globulins promoted survival and multiplication of some cells. A third fraction caused cells to aggregate and form free floating clumps. An adequate chemically defined medium for continuous growth of human cells was used throughout the study. The response of cells to alterations in their environment which simulated some of the effects produced by serum fractions is described.