The microcarrier Cytodex 1 was chosen as the production carrier because the cell density obtained using this carrier was the greatest from the least amount of microcarriers used. Cytodex 3 microcarriers gave a similar cell number as expected but this microcarrier has a pig skin collagen layer on the bead. Cytodex 1 was selected in preference to the other microcarriers because of good cell growth and to remove the issue of animal products in the manufacturing process. We currently use the Cytodex 1 at a level of 5 g l −1 . The growth medium used was Dulbecco's Modified Eagle Medium (DMEM) supplemented with 5% Foetal Approximately 75% of the final volume of cultivation medium and 5 g l −1 of microcarriers were pre-incubated in the culture vessel overnight. The culture parameter set points were controlled by using the Applikon 1030 controlling system for both vessels. The culture pH was maintained by controlling at a set point of 7.2±0.2 by sparging air/CO 2 (90:10%) into the spin filter. Dissolved oxygen concentrations were kept above a minimum set point of 30% saturation by sparging when necessary into a spin filter with air for the 1 l cultures and with pure oxygen in the 15 l cultures. The culture temperature was maintained at 37 • C throughout the cell growth period by use of a recirculating thermocirculator attached to the jacket of the 2 l vessels and in the case of the 20 l vessels the Applikon controlling system used a similar integral recirculating thermocirculator.