EMD produces chemically defined cell culture media that are according to customer requirements
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Chefs know that good ingredients are the most important prerequisite for great meals. Because cell cultures that produce active ingredients for drugs are particularly picky about what they eat, researchers at EMD Millipore in Woburn, Massachusetts, are working on creating a three-star meal for cultures.
A trace less salt, a bit more vitamin... Mike Colman’s “soup” has to satisfy billions of connoisseurs. Although Colman is a biologist rather than a chef, he and his research team at the EMD Millipore site in Woburn, Massachusetts create “meals” that can certainly vie with the cooking feats of a three-star chef. However, Colman does not cook to please human taste buds — he tries to satisfy genetically modified cells for customers, who produce protein-based drugs.
These cells are pickier than many gourmets, as it takes around 50 extremely fine ingredients to satisfy them. The ingredients include sources of carbon such as glucose and glutamine, essential amino acids, vitamins, salts, some fats, essential metals, such as copper, zinc and iron, and trace elements such as selenium cadmium, and others.
Chefs spend a lot of time finding the right suppliers of ingredients, and it is no different when it comes to ensuring the quality of Colman’s cell culture “broths,” as the culture media are often called by lab workers. To create these media, the product management team looks for manufacturers who can ensure that their raw materials will always be of high and — even more importantly — consistent quality.
The slightest contamination of a salt or the smallest fluctuation in the concentration of a vitamin solution could cause the pampered cells in the pharmaceutical companies’ huge fermentation tanks to stop working, and thus possibly lead to huge financial losses. “We make it clear to our suppliers that we require raw materials of consistent quality,” says Colman.
However, when the researchers mix a cell culture medium, they cannot rely on using their tongues to determine the medium’s quality. Instead, state-of-the-art analysis technology has to be used so that the cell culture medium can be systematically tested to determine if the various ingredients are in the right concentration and how the medium changes during the culture’s lifetime.
Ultimately, however, the cells themselves consume the new media and critically assess them, just as the guests in a restaurant do. The cells are given various types of media in tens to hundreds of small-scale tests.
For example, some of the different media might contain higher or lower concentrations of salts. In each of the tests, the researchers check to see if the cells grow better or produce a greater amount of the active ingredient. The scientists can use the stain trypan blue to determine if the soup does not meet the cells’ taste. “Healthy cells exclude the stain, while dead or dying ones absorb it and turn blue,” explains Colman.
Researchers used to have to look through microscopes and count the ratio of healthy (white) to dying (blue) cells by hand to determine the quality of the medium. Nowadays measuring devices can count thousands of cells in no time at all. However, the aim of all of this work is not just to create new and better cell culture media. “We especially want to know why a certain medium works better than another so that we can learn from that for the future,” says Colman.
Customers cannot yet simply order Colman’s cell culture media. “We will launch our first medium in September 2012,” says Colman, who is Head of Pharm Chemicals Solutions R&D at the Woburn site. Cellvento™ CHO-100 is the name of a new product — a medium for Chinese hamster ovary (CHO) cells. These cells are by far the most frequently used mammalian cells for the production of monoclonal antibodies. To date, Cellvento™ CHO-100 has performed as well as or better than conventional media in comparative tests.
The right combination of nutrients is crucial for the reproduction of cells. These cells will later produce active ingredients for pharmaceuticals
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For about one and a half years now, customers have also been able to send their cell culture media recipes to Darmstadt to have them produced by EMD. According to Colman, such custom media manufacturing “caused quite a stir on the market.” Customers have expressed interest in optimizing the medium for their own types of cell cultures, which in some cases have special needs.
Even though most companies work with the same type of cell (CHO cells), the genetically modified CHO cells can vary, explains Colman. Depending on where the active ingredient genes are incorporated into the genome, the cells will have different needs as well as different growth and production properties. “As a result, even two cell lines that produce the same protein sometimes need differently composed media,” says Colman. In addition, the soup must do more than just taste good to the cells and promote their growth and viability, as well as enable for the production of the protein-based drug product.
“Protein production and cell growth compete for the available energy sources,” explains Colman. This is why the medium first has to achieve a certain cell density and maintain it as long as possible so that protein production is kept at an optimal level at all times. However, the medium must also ensure that the protein product is of the right quality. For example, it must not be destroyed by protein-digesting enzymes, which are released into the culture medium by dead cells. Colman’s team in Woburn has been testing all of these components and procedures since 2010. They began testing at a very small milliliter scale before moving on to three-liter bioreactors.
The team has to take into account many details, which Colman originally had never considered. “Although we develop recipes for liquid media, nobody wants to have to cart thousands of liters of water around the world,” he says. The ingredients are therefore put together in powder form. But this raises the question of how to make sure that the rare but necessary trace elements are uniformly distributed in the media delivered in powder form.
In cooperation with specialists at other EMD locations, Colman and his team have always managed to solve such challenges — which is why the Woburn recipes certainly deserve a three-star rating.
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