Evaluation of the new serum-free medium (MDSS2) for the production of different biologicals: use of various cell lines.

The presence of serum in cell culture raises safety problems for the production of biologicals, thus a new serum-free medium (MDSS2) was developed. The evaluation of this medium for the growth of different cell lines (BHK-21 C13, BSR and Vero) has shown that cells grew in this medium similarly to standard serum-containing medium, independently of the culture system used: in static (as monolayer) as well as in agitated systems (in suspension in spinner and perfusion reactors). BHK-21 and BSR cells grew as aggregate cultures and could proliferate in both static and agitated culture systems. Vero cells stayed attached to a substrate and proliferated equally in static and in agitated microcarrier-culture systems. The cell densities obtained with BHK-21 cells depended only on the culture system used. They ranged from 2-3 x 10(6) to 6-12 x 10(6) cells per ml for static batch and perfusion reactor cultures respectively. The cell concentration was 3 to 6 times higher than in classical cultures performed in serum-containing medium. The cell densities obtained with Vero cells were indistinguishable from those obtained in serum-containing medium, whatever the cell culture system used. These cell lines have been used for the production of rabies virus. With respect to BHK-21 and BSR, similar production rates of rabies glycoprotein have been found as in the standard roller bottle process. The production of rabies virus and of viral glycoprotein by Vero cells cultivated in serum-free medium was augmented 1.5-fold and 2.5-fold, respectively, when compared to serum-containing medium. A recombinant BHK-21 cell line, producing human IL-2, can also proliferate in MDSS2, after addition of insulin. The specific IL-2 production rate was augmented 3-4-fold in comparison to serum-containing medium. For the cells tested, the MDSS2 serum-free medium is a good growth and production medium. Its use for cultivating other cell lines and/or for the production of other biologicals is discussed.