A new seed-train expansion method for recombinant mammalian cell lines

Area of Science:

• Biotechnology
• Cell Culture Technology
• Bioprocess Engineering

Background:

• Mammalian cell line expansion is critical for recombinant protein production.
• Conventional seed train methods can be time-consuming and prone to variability.
• Optimizing cell thawing and initial culture steps is essential for efficient bioprocessing.

Purpose of the Study:

• To develop and validate a new method for minimizing time and enhancing control during seed train expansion of recombinant mammalian cell lines.
• To assess the feasibility of using large-volume cryo-bags for direct inoculation into a modified bioreactor.
• To compare the efficiency and consistency of the new method against conventional cryo-vial based approaches.

Main Methods:

• Utilized 50 or 100 ml cryo-bags with high-density frozen cells (20-40 x 10^6 cells/ml).
• Thawed cryo-bag contents were directly transferred into a modified 2-liter bioreactor with controlled parameters (pH, DO, temperature).
• The process was tested for recombinant Baby Hamster Kidney (BHK) and Chinese Hamster Ovary (CHO) cells.

Main Results:

• Reduced the seed train expansion time by 25-30 days compared to conventional cryo-vial methods.
• Achieved consistent scale-up with fewer manual operations and subjective decisions.
• Observed similar cell metabolic rates and product integrity compared to control experiments.
• Demonstrated that a wash step to remove DMSO is not necessary prior to inoculation.

Conclusions:

• The cryo-bag and modified bioreactor approach offers a more efficient and controlled method for initiating seed train expansion.
• This one-step technology streamlines the scale-up process, improving reproducibility in biopharmaceutical manufacturing.
• The method simplifies operations and maintains cell performance, making it a viable alternative to traditional techniques.