Improvement strategies for transient gene expression in mammalian cells
Yushun Fu, Zimeng Han, Wanting Cheng, Shuaichen Niu, Tianyun Wang, Xiaoyin Wang
Abstract
The proportion of biopharmaceuticals in the global pharmaceutical industry is continuously expanding with a steadily growing market scale. By 2024, the global biopharmaceutical market value will reach $389 million (O’Flaherty et al. 2020 ). The production of recombinant therapeutic proteins (including antibodies) is an important aspect of biopharmaceuticals, and their expression systems contain bacteria, yeast, mammalian cell lines, and plants. Chinese hamster ovary (CHO), mouse myeloma (NS0), mouse myeloma (Sp2/0), and human embryonic kidney 293 (HEK293) cells are commonly used mammalian cell systems. Out of the 107 products obtained from mammalian systems, 95 (89%) of them were produced using the CHO cells, making it the most commonly used system (Walsh and Walsh 2022 ). HEK293 and CHO cell lines are suitable hosts for therapeutic protein production because of their post-translational modifications (PTMs) similar to human cells, particularly glycosylation (Delafosse et al. 2016 ). CHO cells can produce proteins with complex structures, can be cultured on a large scale, and are less susceptible to viral infection (Zhang et al. 2013 ; Ward and Ober 2018 ; Wang et al. 2019 ). HEK293 cells grow easily and reproduce rapidly in serum-free suspension culture, exhibit high transfection efficiency using the most common transfection reagents, and are commonly used as models for drug discovery and toxicity testing (Hu et al. 2018 ).