Transgene mRNA Levels and Stability are Key Factors to Enhance Transient Gene Expression in CHO DG44 Cells
The aim of this work was to identify some of the limiting factors in transient gene expression (TGE) in CHO cells and to propose strategies to overcome them. Increasing the amount of plasmid DNA in the transfection did not increase recombinant protein yields, and it had a negative impact on transgene mRNA levels. Therefore, two other strategies aimed at increasing transgene mRNA levels were investigated. The first involved hypothermic treatment of transfected cells and the second the addition of valproic acid (VPA) after transfection. Both strategies resulted in recombinant antibody yields of 40–60 mg/L, whereas the untreated control transfections produced only 5–10 mg/L. In the treated cultures, the steady-state level of transgene mRNA was 3–5 times higher than in the untreated cultures and remained stable up to 6 days post-transfection. The two strategies proposed here are cost-effective and scalable making large-scale TGE in CHO cells a feasible alternative for rapid production of gram amounts of recombinant protein.
KeywordsChinese Hamster Ovary Cell Chinese Hamster Ovary Sodium Butyrate Recombinant Protein Production Transient Gene Expression
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