Selecting and designing cell lines for improved physiological characteristics.

We have developed several approaches to create cell lines with improved characteristics in cell culture. In some cases it has been possible to isolate natural variants with useful properties. Cholesterol independent variants of the mouse NSO myeloma cell line were isolated by cloning in a selective medium. A glutamine independent variant of a hyridoma was isolated by continuous (chemostat) culture under glutamine limited conditions in the presence of glutamate. Choline independent cells were isolated from a choline limited chemostat. In an alternative approach to modifying cell behaviour, we have used recombinant DNA techniques to introduce the glutamine synthetase (GS) gene to a hybridoma. This resulted in glutamine independence and increased productivity.

Production of recombinant proteins in serum-free media.

The advantages of serum-free culture for the manufacture of recombinant biopharmaceuticals from mammalian cells are reviewed. The process favoured is fed-batch serum-free cell culture. This process is applicable to the majority of cell lines, is practical on the large scale, gives the lowest manufacturing cost, and can be carried out without the use of any serum.

Growth and oxygen requirements of antibody producing mouse hybridoma cells in suspension culture.

Mouse hybridoma cells producing a monoclonal antibody to anti-B blood group antigen have been grown in airlift fermenters up to 30 litres capacity. As a prerequisite for scaling the process up, the oxygen utilization rate of the cells has been established by a dynamic method using an oxygen electrode. The data is compared with that obtained from a chemostat under oxygen limited steady state conditions.