Adaptation of Recombinant HEK-293 Cells to Growth in Serum Free Suspension

Abstract

HEK-293 cells are a popular host for the generation of stable cell lines for recombinant protein production, and particularly cloned membrane receptors which are required continuously for screening of drug targets. The purpose of this work was to adapt cell lines to growth in suspension culture in order to increase efficiency. This objective was achieved with three recombinant HEK-293 cell lines expressing 5HT receptors, which were successfully adapted for robust growth in suspension culture using a new serum-free medium, Ex-Cell 520 (JRH Biosciences). The adaptation process was cell line dependent and the time scale of this process varied between 4 and 8 weeks. Cells were observed to grow as a mixture of single cells and loose aggregates and could be repeatedly passaged in the range of 6 × 10⁴ cells/ml to 1 × 10⁶ cells/ml with a doubling time of between 24 and 35 hours (cell viability of 95%). In summary, the adaptation process resulted in an increased specific cell productivity, and cell growth rates equivalent to standard cultures and all three cell lines have now been successfully scaled to growth in 50L and 100L bioreactors. In addition, the process achieved an estimated 5-fold reduction in consumable costs.