Cell Culture

The growth in biopharmaceuticals is creating an unprecedented increase in demand for cell culture products. Cell culture techniques have been used in biological sciences for more than 50 years; however, cell culture techniques have been applied to production systems for only about 26 years. The cell culture industry, which began in the late 1980s from the utilization of recombinant DNA technology and cell hybridization, is today a major underpinning of the biopharmaceutical market.

The choice of cells to use in biopharmaceutical production depends on a number of factors, some technical and some economic. Bacteria and yeast, for instance, are relatively simple to grow. Each cell of a bacterium or yeast is an independent organism capable of its own metabolism. Yeasts and bacteria have fairly simple nutritional needs and grow well suspended in a liquid medium, as well as in large fermentors.

Various kinds of cells can all be made to express the same protein. However, a protein produced by a bacterium may have different effects than the same protein produced by animal cells. After a protein is expressed in the cell, it goes through a process called posttranslational modification. Molecules of sugars and carbohydrates attach themselves to the protein (a process called glycosylation). The protein may fold itself into a different configuration, changing the surface available to attach to other molecules in the body. Folding and glycosylation have a great effect on the ability of a protein to be used for a particular process, and different types of cells perform these modifications in different ways. The choice of the right cell to culture may result in a protein that is more appropriate for use—or in the elimination of extra steps in the manufacturing process.