N-1 Perfusion

A form of seed train intensification, N-1 perfusion refers to the intensification of cell growth in the seed train step (N-1) before the production bioreactor (N), achieving a more rapid and robust process while maintaining an existing Fed-Batch based production scheme.

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N-1 perfusion is done by attaching a cell retention device, such as the XCell ATF^® Device, to the N-1 bioreactor to attain high cell density and viability. This seeds the N production bioreactor at a higher starting cell density and shortens the production bioreactor run time. The process dramatically increases facility output without direct change to the core Fed-Batch production process. A robust cell retention device is required to attain a high cell density inoculum for the production bioreactor.

The combination of implementation ease and productivity increase makes N-1 perfusion the most frequent starting point for upstream intensification. Once in place, further intensify the seed train by adding High Productivity Harvest (HPH) to the N bioreactor or transition to continuous.

Repligen solutions help overcome key challenges in N-1 perfusion, with hands-on process and implementation consultation from global Field Applications Specialists.

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N-1 Perfusion Cell Culture Workflow

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Boost throughput, save time

N-1 perfusion intensifies the Fed-Batch process, increasing facility throughput. Seeded at a higher initial density, cells in the N bioreactor grow faster, reach a higher max VCD and produce more product than traditional Fed-Batch. Harvest sooner and increase the number of batches per year as compared to a standard Fed-Batch process. Alternatively, maintain the N bioreactor run time to increase overall yield.

Maintain a Fed-Batch process

N-1 perfusion intensification increases N bioreactor productivity and throughput while maintaining a Fed-Batch process. No perfusion or media exchange of the N bioreactor is required, allowing the N bioreactor to maintain a single and discreet Fed-Batch harvest point.

Minimize validation impact

Intensify with minimal process modifications and regulatory edits. No additional equipment is connected to the N bioreactor, no media exchange occurs during the production run and cell viability is higher, typically leading to lower impurity values.

N Bioreactor reached 350 x 10⁶ VCD

N-1 perfused Fed-Batch reached 350 million cells/mL VCD in just 6 days. In comparison, standard Fed-Batch achieved 30 million cells/mL viable cell density (VCD) over a course of 14 days. Productivity of the N bioreactor with N-1 perfusion increased 20X while maintaining viability above 90%.

Higher cell density and viability

10X VCD over Fed-Batch
VCD as high as 350 x 10⁶ cells/mL
50% reduction in production time
20X increase in productivity
Lower COGs

N-1 Perfusion increased VCD 10X, reduced production time by 50%

The perfused N-1 bioreactor cell density rapidly increased from 8 to 80 million cells/mL (10x VCD) in 4-5 days. Inoculation of the N bioreactor with the N-1 perfused culture established a 10X higher initial viable cell density over Fed-Batch (A). After 3 days, the N-1 inoculated bioreactor achieved 35 million VCD. In comparison, the control required 6 days to achieve 25 million VCD (B).

Leverage higher VCD to either increase throughput or increase yield. Harvest of the N-1 Fed-Batch bioreactor at day 8 was equivalent to harvesting the Fed-Batch control at day 14, saving 6 days of N bioreactor suite time (C). Alternatively, harvest the N-1 Fed-Batch process at day 14 for a 25% overall yield increase.

N-1 bioreactor reached 10X VCD in 4-5 days
N-1 perfused Fed-Batch bioreactor reached maximum VCD of 35 million compared to 25 million with traditional Fed-Batch
Maximum VCD was achieved 3 days earlier
Harvest 6 days earlier for same yield OR
Achieve 25% yield increase by day 14

N-1 Bioreactor VCD

Production Bioreactor VCD

Production Bioreactor

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