Effect of culture operation mode on NT2 cell expansion as 3D-aggregates. Cells were cultured in spinner vessels (SP) or in bioreactors (BR), with inoculum concentration of 4 × 105 cell/mL, using different operation modes: batch (SP-4B, black line and triangles), fed-batch (SP-4FB, dashed line and white triangles) and media exchange (SP-4ME, dashed line and black triangles, and BR-4ME, grey line and triangles). Concentrations of glucose (A), lactate (B), glutamine (C) and ammonia (D) presented in media during culture time. Specific rates of glucose consumption and lactate production shown over the course of exponential growth phase (E) (day 2- white bars, day 3- grey bars, day 4-striped bars, day 5- black bars). Growth curves expressed in terms of cell concentration; error bars denote standard deviation of average from 2 independent experiments (F).