Optimization of Culture Conditions to Improve Follicle-Stimulating Hormone Production by CHO-DG44 Cells in Serum-Free Medium

Background: In the present study, we attempted to adapt an adherent and serum-dependent Chinese hamster ovary DG44 cell line to a serum-free suspension culture and optimize the culture condition to achieve a higher yield of recombinant human follicle stimulating hormone (r-hFSH) with acceptable quality. This approach helps to mitigate the risks associated with blood-borne pathogens, reduces lot-to-lot variability, and lowers costs, making it suitable for industrial processing and scale-up. Methods: The cell adaptation was performed using different chemically defined SFM. This process was followed by optimization through statistical experimental design, focusing on selected physicochemical parameters, including chemical supplementation of the medium and temperature shift. Both small- and large-scale cultures were conducted to test the reproducibility of the optimized condition. The expressed protein was evaluated for comparability with the standard molecule according to the Pharmacopeia guidelines. Results: response surface methodology (RSM) analysis indicated that supplementation of the culture medium with galactose and sodium butyrate (NaBu), along with a temperature downshift, were the main parameters leading to increased cell viability (10%), r-hFSH level (96%), and more importantly, the glycosylation content (49%) of r-hFSH compared to the control condition. Conclusion: As r-hFSH isoforms generated during in vivo post-translational modifications typically exhibit different serum/plasma half-lives and bioactivity due to their incorporated sialic acid content/glycosylation, further optimizations of r-hFSH production are necessary to enhance its biological activity. In this study, following a primary screening of the studied parameters, optimization of culture conditions based on selected parameters resulted in enhanced quality and quantity of the produced r-hFSH. However, further examination is necessary before transitioning to industrial production.