eShop
English
Introduction
With the surge in demand for production in the biopharmaceutical market and the widespread adoption of the Quality by Design (QbD) concept, traditional fed-batch culture methods can no longer meet the increasingly stringent cost control and production flexibility requirements of biopharmaceutical companies. Perfusion culture, as an efficient cell culture technology, has gradually become the core focus of industry process intensification due to its significant advantages of high cell density, high yield, and short residence time.
The core challenges of perfusion processes lie in the stability of high-density cell retention, precise control of fluid dynamics, sustainability of long-term culture, and feasibility of scaled-up production. Cobetter ATF series products, based on Alternating Tangential Flow (ATF) Filtration technology and centered on hollow fiber membranes, systematically address these pain points, providing end-to-end support for perfusion processes.
01 Why Choose Perfusion
Compared with Fed-Batch, the perfusion process has significant advantages:
1. Higher viable cell density and productivity per unit volume: The peak viable cell density in perfusion culture is generally several times higher than that in Fed-Batch, which can significantly improve production efficiency per unit volume.
2. Better product quality: The perfusion process allows a good culture environment to be maintained for a long time, effectively reducing the level of cellular metabolic stress, while significantly lowering the accumulation of harmful metabolic by-products such as lactate and ammonia, ensuring batch-to-batch consistency of key quality attributes of the target product.
3. Controllable economic cost: Although the medium consumption of the perfusion process is higher, its ability to significantly increase single-batch yield means that, especially in the currently popular IFB or IPFB processes, the cost of reagents and key consumables required per gram of product is actually comparable to that of feed-batch processes, or even lower.
4. Shortened development and production cycle: For products with low single-cell expression levels or poor product stability, using the perfusion process for the initial expression can effectively shorten the process development cycle and accelerate project progress.
02 Common Perfusion Processes
1. Intensified Fed-batch (IFB): Typically using a 0.2 μm filtration module, while keeping the basic operation mode of the traditional Fed-Batch process unchanged, using perfusion amplification technology in the N-1 stage can effectively shorten the seed train and significantly increase the initial inoculation density and peak viable cell density in the N stage. By optimizing nutrient supply and metabolic control during the culture process, the yield per unit volume and production efficiency can be significantly enhanced.
2. Intermittent-perfusion fed-batch (IPFB) and Concentrated fed-batch (CFB): Based on traditional Fed-Batch or IFB processes, using a 50 kD filtration module, the target product and cells are retained in the bioreactor, and medium exchange is carried out continuously or periodically. This maintains high cell density and high viability, significantly increasing single-batch yield while ensuring product quality. Feed medium is added as needed during the culture, and harvesting is done entirely at the end of the culture.
3. Continuous perfusion culture (CPC): Typically using a 0.2 μm filtration module, cells are retained in the bioreactor, while fresh medium is continuously added to the bioreactor at a rate matching the culture volume, and the product-containing supernatant is removed. Cells may be periodically discharged if necessary to maintain a certain cell density and viability, enabling extended culture periods of weeks or even months and achieving high cumulative yield per unit volume.
03 Precautions for Implementing the Perfusion Process
A successful perfusion process is not achieved overnight; during its development, the following dimensions must be carefully considered:
1. Selection of Cell Retention Device
The cell retention device is the core carrier of the perfusion process. Common components used to implement perfusion processes include rotary membrane filters, settling systems, and tangential flow filtration systems. Currently, devices based on the hollow fiber filtration principle have become the industry mainstream, among which the most representative are ATF (Alternating Tangential Flow) and TFF (Tangential Flow Filtration) technical paths.
A detailed comparison of the two mainstream technical paths is shown in Table 1.
Table 1. Comparison of ATF vs. TFF
2. Key Process Parameter: Cell Specific Perfusion Rate
The Cell Specific Perfusion Rate (CSPR) is the most critical design parameter in perfusion processes, representing the volume of culture medium required per cell per day. Determining the minimum CSPR (CSPRmin) is crucial for optimizing medium utilization efficiency and reducing costs. If the CSPR is too low, it leads to inadequate nutrient supply; conversely, an excessively high CSPR can cause unnecessary cost and an elevated downstream purification burden. It is recommended to control the CSPR as low as possible, below 50 pL/cell·day.
3. Strategic Optimization of Culture Medium
In perfusion processes, basal medium is often insufficient to support ultra-high-density cell growth. Studies have shown that adding feed medium (such as Feed A/B) during perfusion can directly double the viable cell density from 40×10^6 cells/mL to 80×10^6 cells/mL, with cell-specific growth rate increasing by approximately 230%.
4. Scale-up and Scale-up Effects
Scaling up from laboratory scale to 2000L or even larger commercial production requires ensuring that the ratio of hollow fiber column membrane area to culture volume remains within a reasonable range to control the theoretical shear at the recirculation end and the transmembrane flux values.
04 Cobetter XperCell™ ATF Series Hollow Products
Based on the above selection logic, the Cobetter XperCell™ ATF series products specifically address core pain points, providing reliable ATF component solutions for biopharmaceutical customers both domestically and internationally. Detailed product information is shown in Table 2.
1. Excellent Material Foundation: PES Hollow Fiber Membranes
The core advantage of the Cobetter XperCell™ ATF series lies in its self-produced polyethersulfone (PES) hollow fiber membranes.
Low extractables levels and good cell compatibility: PES material has low extractables levels and a lower risk of introducing potential impurities during bioprocessing, ensuring a safe environment for cell growth.
Precise retention: Cobetter offers different pore size options (e.g., 50 kD, 0.2 μm) for different products (such as monoclonal antibodies, recombinant proteins, vaccines), effectively retaining cells or products while allowing products or metabolic waste to be smoothly discharged.
2. The "Hardcore Performer" for High-Pressure Steam Sterilization
Cobetter stainless-steel ATF series have good high-temperature stability and can withstand conventional high-pressure steam sterilization procedures, ensuring high process flux and membrane integrity after multiple sterilizations. All products are sterilized by high-pressure steam and undergo integrity testing before release to ensure no leakage risk after sterilization.
3. Good Operational Convenience and Flexible Options
Cobetter single-sue ATF series offer good operational convenience. The pre-wetted storage method efficiently maintains the membrane pore structure, and only a small amount of sterile purified water or water for injection is needed to rinse the membrane column before use. The single-use ATF series covers pore sizes of 0.2 μm and 50 kD, meeting the operational convenience needs at different stages of the customer’s process.
4. Wide Scalability and Customization Services
Whether you are at the R&D or commercialization stage, Cobetter can provide a matching solution:
Wide scale coverage: The products are currently suitable for cell culture scales ranging from 1L to 2000L.
Customized development: For special process requirements, Cobetter provides product customization services, flexibly adapting to different bioreactor configurations and process goals.
5. Strict Quality System Assurance In the biopharmaceutical field, safety always comes first. Cobetter ATF products are manufactured in an ISO Class 7 clean environment and undergo 100% integrity testing and water flux testing before leaving the factory.
Each component shipped comes with detailed quality documentation, meeting the safety production and audit requirements of biopharmaceutical customers, and helping customers with compliant submissions.
Table2. Information of Cobetter XperCellTM ATF series products
05 The Future is Here: From Intensified Processes to Continuous Manufacturing
With the continuous promotion of perfusion culture processes, their application is no longer limited to the expression of unstable proteins. In the field of monoclonal antibody production, intensified processes involving N-1 perfusion amplification and N-stage product retention (IFB, IPFB, and CFB) are becoming powerful tools for increasing yield. By introducing perfusion at the N-1 stage, it is possible to obtain seed cells in the logarithmic growth phase at densities up to 100×10^6 cells/mL or even higher. During the N-stage expression stage, the introduction of 50 kD membrane columns achieves the dual purpose of removing metabolic waste while effectively retaining the target product. The application of similar intensified processes can significantly shorten production cycles and improve facility utilization.
In such intensified processes and even in future fully continuous manufacturing processes, the ATF system is not only a tool for cell retention but also a bridge connecting upstream and downstream operations. Cobetter ATF hollow fiber products, with their stable performance and reliable quality, are helping pharmaceutical companies overcome the technological barriers of process intensification, achieving a transition from "following" to "pace matching ."
The choice of perfusion process is a systematic project, involving the intersection of cell biology, fluid dynamics, and materials science. Selecting a thoroughly validated and stable-performing cell or product retention device represents half of the success in the development and application of perfusion process. Cobetter XperCellTM ATF series hollow fiber columns, with their excellent material properties, strict quality control, and flexible service system, are becoming a reliable partner in this field, helping biopharmaceutical companies worldwide reduce costs, increase efficiency, and pioneer the future of intelligent manufacturing.
