Intensifying Your Process With High-Density Cell Bank Manufacturing
Process intensification aims to increase bioprocess productivity while reducing the time, resources, and process steps required to manufacture a product. In upstream processing, strategies such as concentrated fed-batch and perfusion culture can support higher cell densities and greater productivity from a given bioreactor volume, helping manufacturers produce more within a smaller process footprint.
But process intensification doesn’t have to start at the production bioreactor.
Seed train intensification
In a typical seed train, cells are expanded across a series of progressively larger culture vessels until the desired biomass is reached. Extended seed trains can introduce several challenges:
- Long timelines
- Increased risk of genetic variation due to additional cell passages
- High resource demand
- Large footprint
- Greater operational complexity
- Increased contamination risk
Starting with more cells can help address these challenges by eliminating intermediate expansion steps. This creates a shorter, simpler seed train that can reduce timelines, resource requirements, and cost of goods.
What is a high-density cell bank?
A high-density cell bank is a working cell bank containing substantially more cells per vial than a conventional cell bank. This provides a larger number of viable cells immediately after thaw, enabling inoculation of larger culture vessels and supporting more cost-effective, intensified seed trains.
To get the full benefit of seed train intensification, the cell bank needs to reliably deliver the required cell density and post-thaw viability. Manufacturing timelines and cost-efficiency are also important considerations when selecting a cell banking partner.
Below, we explore how the Sartorius high-density cell bank manufacturing process addresses these requirements.
Manufacturing a high-density cell bank
The Sartorius high-density cell banking workflow (Figure 1) uses a single-use, closed-loop process enabled by aseptic solutions including Biowelder® connectors, Biosealer® disconnectors, and Mycap® bottle closures.
Semi-automation throughout the workflow, including automated filling, helps minimize manual handling, contamination risk, and overexposure to cryoprotectants.
- Cells are thawed into 125 mL shake flasks within a Grade A isolator
- In a Grade C cleanroom, cells are expanded from shake flasks into Flexsafe® RM perfusion bags and cultured in the Biostat® RM system in perfusion mode. Flexsafe® RM perfusion bags are equipped with BioPAT® Viamass sensors, which are used as part of a patented strategy to determine the media feed rate during perfusion and achieve the target cell density.
- During harvest, a patented volume-reduction process within the Flexsafe® RM perfusion bag eliminates the need for centrifugation.
- Cells are transferred to sterile vessels with the client’s preferred cryopreservation medium.
- In a Grade A isolator, cells are aseptically filled into cryovials using automated filling. Standard filling is up to 100 million cells/mL at a 4.5 mL fill volume, with the process adaptable to specific requirements.
- Cells undergo controlled-rate freezing and are stored.
Figure 1: The high-density cell bank manufacturing workflow at Sartorius
By combining a closed cell banking workflow with perfusion culture, PAT-based media feed control, and a patented centrifugation-free harvest strategy, the process is designed to minimize handling and cell stress while achieving high cell densities:
- > 35 × more cell bank material, helping reduce intermediate seed train expansion steps
- Up to 450 million cells/vial, supporting direct inoculation of larger culture vessels
- > 500 vials filled in < 20 minutes, limiting manual handling and exposure to cryoprotectants
- Harvest to storage in < 2 hours, minimizing processing time and cell stress
What else should you look for in a cell banking partner?
Getting the right cell density is only one part of a successful cell banking strategy. The process also needs to work for the specific cell line and manufacturing requirements, operate under appropriate GMP controls, and be supported by the testing and release activities needed for a robust starting material.
Sartorius combines high-density cell bank manufacturing with a flexible approach to different project and process requirements, established GMP manufacturing experience, and integrated cell bank testing and release.
Flexibility
High-density cell banking needs to be adapted to the specific cell line and intended manufacturing process. Sartorius can support either a platform approach or technology transfer, with pilot and engineering runs used to establish the process before GMP manufacturing. The service can also support both Sartorius and non-Sartorius mammalian suspension cell lines.
Track record
Sartorius has manufactured, tested, and QP released more than 120 GMP cell banks since 2018. Cell banks are manufactured in an MHRA-licensed cGMP facility using controls designed to minimize manufacturing risk, including batch segregation, unidirectional airflow, sporicidal control of raw materials, and animal-component-free processing.
Integrated testing
Appropriate cell bank testing and characterization are essential to establishing a robust and reliable cell bank. Sartorius provides extensive in-house biosafety testing and cell line characterization services, with expertise covering microbial and viral safety, cell line identity, and genetic stability. Ready-to-use testing schemes are avaialble where appropriate or can be adapted to the requirements and risk profile of a specific program.
Bringing these capabilities together means testing can be integrated with cell bank manufacturing rather than managed as a separate activity. For high-density working cell banks, manufacturing, testing, and QP release can be completed in three months.
Start process intensification earlier
Reducing the number of seed train expansion steps can shorten upstream timelines, lower media, equipment, and operator requirements, and help reduce cost of goods.
Starting with more cells is one way to achieve this, and high-density cell banks provide the concentrated starting material needed to support seed train intensification. By increasing the number of cells available per vial, high-density cell banks can also reduce the number of vials required, lowering associated storage and shipping requirements.
Together, these benefits can create a shorter, more efficient route to production.
Learn more about our cell banking services or browse our comprehensive biologics testing capabilities.
