Combinatorial treatment with lithium chloride enhances recombinant antibody production in transiently transfected CHO and HEK293E cells

Lithium chloride (LiCl), which induces cell cycle arrest at G2/M phase, is known as a specific production rate (q_p)-enhancing additive in recombinant Chinese hamster ovary (CHO) cell culture. To determine the potential of LiCl as a chemical additive that enhances transient gene expression (TGE), LiCl was added to the CHO-NK and human embryonic kidney 293E (HEK293E) cell cultures before and/or after transfection with polyethylenimine as a transfection reagent. The effect of this addition on transfection efficiency (pre-treatment) and qp enhancement during TGE (post-treatment) was examined. For the TGE of monoclonal antibody (mAb) in CHO-NK cells, pretreatment alone with 10 mM LiCl and post-treatment alone with 5 mM LiCl resulted in 1.2- and 3.4-fold increase of maximum mAb concentration (MMC), respectively, compared with the TGE without LiCl treatment. Furthermore, combinatorial treatment with LiCl (10 mM for pre-treatment and 5 mM for post-treatment) synergistically increased the TGE of mAb (5.3-fold increase in MMC). Likewise, combinatorial treatment with LiCl (10 mM for pre-treatment and 15 mM for post-treatment) in HEK293E cells synergistically increased the TGE of mAb (4.9-fold increase in MMC). Taken together, the data obtained here demonstrate that combinatorial treatment with LiCl is a useful means to improve TGE in CHO as well as HEK293 cells.