Sampling and Harvesting

1. Remove 1-mL samples daily using a 2-mL syringe to assess the culture (see Note 16). To do this, put the MiniPERM on a stand and turn it so that a Luer-Lock sampling port is at 12 o'clock position. Open the port and insert the 2-mL syringe (see Note 17). Rotate the device 120 degrees clockwise so that another port is at 12 o'clock and the sample port used for withdrawal is now at the 4 o'clock position.

2. Assess cell viability using nigrosin exclusion (see Note 18).

3. Harvesting is performed using the method described for sampling, with the exception that a larger quantity of medium is removed using a 50-mL syringe. Harvest 20 mL either when the cell viability falls below 50% or when the cell density exceeds 2 x 107 cells/mL. The remaining 15 mL of cell suspension allows for repopulation of the production module after the addition of 20 mL fresh production medium.

4. Change the medium in the nutrient module every 2 to 4 d (see Note 19). Proceed with harvesting and replacement of nutrient media in a cyclic manner.

5. After sampling and harvesting the Luer-Locks must be wiped down with 70% ethanol to prevent infection being introduced to the production module (see Note 20). Periodical measurement of cell density, viability, and antibody production during the course of the production run will help in the planning of future production runs.

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