Perfusion technology is a tool to increase productivity that can be applied at different stages during upstream cell culture for biotherapeutics products. Perfusion allows removal of waste by-products and replenishment of fresh nutrients so that the cells are able to grow and reach higher cell densities and higher productivity. N-1 perfusion, the application of the perfusion technology in the step immediately before the production bioreactor, is a good option for processes that exhibit low productivity. Join Claudia Berdugo, Ph.D., Director of Process Development at Catalent Biologics, where she discusses N-1 perfusion and how Catalent Biologics works toward process improvements for each client to enable them to move their pharmaceutical products forward with confidence.
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Perfusion is a technology that allows removal of waste by-products and replenish with fresh nutrients so the cells always have a nice environment to grow and can reach higher cell densities and higher productivity. N-1 refers to the step previous to the production bioreactor, N-1 perfusion is the application of the perfusion technology in the step immediately before the production bioreactor, since higher cell density will be reached in the N-1 stage the production reactor or N stage can be inoculated at a higher seed density than with a traditional seed train.
Perfusion technology is a tool to increase productivity and can be applied at different stages in the upstream cell culture, for example :
Cell banks: cells can be grown in creating cell banks since higher cell density can be obtained large number of vials can be generated or bags at a very high cell density that can be used later to start the seed train or even the production bioreactor
Seed train intensification: Higher cell density reached as we pass cells previous to the reactor and can inoculate reactor with higher cell density, in addition bioreactor steps can be skipped
Production bioreactor: Perfusion can be applied in the production reactor at different production modes
- Concentrated fed batch: where no product is removed
- Steady State: constant removal of product and cells reach steady state concentration
- Dynamic Perfusion: product can be removed and cells reach high peak VCD
What are the benefits of N-1 perfusion? Why do some companies want use N-1 perfusion as part of their process?
As the bioreactor is inoculated with higher cell density the duration of the bioreactor can be reduced achieving the same titer as in fed batch, alternatively higher titer can be reached with a longer duration in the feed batch when inoculated at higher cell density from a perfusion N-1
Media consumption in perfusion and N-1 perfusion is a key point to consider and should be optimized to avoid impact on cost of goods. Media manufacturers have been working on potential solutions to provide media suitable for the high viable cell densities and high metabolism expected in this mode of culture. Specifically, with N-1 perfusion, the impact on cost of goods is less severe than in production perfusion because the perfusion mode is shorter (usually 5 to 7 days) and the volume is lower than a production reactor. Traditional media used for fed-batch can still be used for N-1 perfusion. Additionally, the cost of media consumption can be offset by reducing the duration of the production bioreactor and by the higher productivity expected from the production bioreactor inoculated at higher cell density from N-1 perfusion.
N-1 perfusion Is a good option for processes with really low productivity. We work with our customers to evaluate their needs to determine which approach best fits their molecule and program goals.
N-1 perfusion can be incorporated into a production process in a variety of ways. It can be incorporated into process intensification as part of a fully continuous process. Or it can be performed in a hybrid batch/continuous process in which the upstream and/or downstream processes remain in batch mode. The main goal is to increase productivity and facility utilization.
For seed train expansion, do you find that you need a more complex media with perfusion? Have you found any supplements that are very useful to support high densities?
Media optimization is highly recommended for perfusion processes. Customized media can be designed with the right balance of components appropriate for high cell density cultures. Every process may require a different balance of nutrients for production, but for N-1 perfusion, it is likely that a base media with specific supplementation will work well to achieve the goal of increasing cell density while avoiding the accumulation of toxic metabolites for the cells. For production perfusion, the optimization may need to include additional supplementation to maintain growth and achieve the desired product quality.
How much automation are you able to incorporate into your perfusion processes for production? Can it be a fully automated or close to fully automated process?
The industry is working toward solutions that enable fully automated processes that will allow better control and improve the robustness of the process. Automation includes various components. Some of them are well established and routinely used in perfusion, such as capacitance probes. Other components that are part of perfusion systems require additional work to be integrated with the bioreactor systems. For example, automated cell bleeding can be achieved by integrating a continuous pump with an online cell density probe. For production perfusion, advanced automation tools are being developed to monitor product quality as well. A collaborative approach is needed between vendors and facility owners to achieve full automation of N-1 and perfusion processes.