Cell metabolism and medium perfusion in VERO cell cultures on microcarriers in a bioreactor

Abstract

Parameters of VERO cell growth and metabolism were studied in cultures performed on microcarriers (MCs) using a bioreactor with a working capacity of 3.7 l. Kinetic studies of VERO cell growth in batch, semi-batch and perfusion cultures using concentrations of 2 and 10 mg/ml of MCs showed that a high concentration of MCs (10 mg/ml) and the use of medium perfusion allowed the attainment of higher final yields of VERO cells (6 × 10⁶ cells/ml after 10 days of culture). Perfusion also allowed better use of MCs as indicated by the observation of about 100% of MCs totally covered by cells and the appearance of multilayered cells on 64% of MCs after 13 days of VERO cell culture with 2 mg/ml of MCs. Concerning the concentration of nutrients in the cultures, the medium perfusion was able to sustain suitable levels of galactose and glutamine, which quickly decreased after 4 days in batch cultures. The air inlet in the batch cultures was capable of eliminating the NH₄ ⁺ which accumulated in the medium culture. Lactate accumulated during the first days of culture but then was utilized by the cells and decreased along the culture time. The optimization of VERO cell cultures on microcarriers as indicated by the concentration of MCs, medium perfusion and air inlet is discussed.