P-76: Stepwise Reduction of Fetal Bovine Serum Levels in Chinese Hamster OvaryCells -Expressing Human Chorionic Gonadotrophin- Culture

Background: The demand for producing recombinant therapeutic proteins by mammalian cell lines, such as Chinese hamster ovary (CHO) cells, continues to grow. Significant achievements in process optimization including development of cell culture strategies for largescale and cost-effective production have been made. Fetal bovine serum (FBS) is an often essential growth supplement and yet most costly component for cell culture media. Furthermore, scientific and ethical concerns about the use of FBS considering its harvest and production highlight the need for replacing or reducing FBS levels in cell culture. In this study the effect of different serum concentrations on viability and productivity of a recombinant CHO cell line expressing recombine human chorionic gonadotrophin (rhCG) was investigated. Materials and Methods: FBS was used by 15% concentration as the reference and the levels have downward trend during one or two passages at each stage, for instance 15 to 10, 5, 3, 1%. Cells growth and morphology were studied daily by optical microscope and cell viability was determined by trypan blue exclusion. Total protein concentration was estimated using Bradford assay. The rhCG production was assessed using SDS-PAGE and Western blotting methods. Results: The results demonstrated that cell growth and morphology were normal through gradual reduction of serum levels from 15 to 3%. Maximum cell viability observed at 15% FBS while cells longevity reached its maximum at 3% FBS. SDS-PAGE and Western blotting results showed that rhCG expression reduced from 15% FBS to 1%. Maximum productivity was seen at 15% FBS and no significant difference in rhCG production at 3 and 5% of FBS was found. Conclusion: Remarkable amount of money could be saved by reducing FBS levels by 80%, while the viability and productivity of rCHO cells don’t change significantly.