Complete Growth Medium
The base medium for this cell line is BalanCD HEK293 (Irvine Scientific cat# 91165). To make the complete medium, add to 475 mL of the base medium:
Subculture cells at log phase (when cells are ready for passaging, i.e., every 2-3 days, and are approximately 2 x 106 cells/mL). Pre-warm fresh growth medium prior to use. Swirl the flask gently to evenly distribute cells in medium. Remove a small volume of cells from the flask and perform cell count.
1. Seed at 5x105 cells/mL for a 2 day subculture and 4x105 cells/mL for a 3 day subculture (weekend)
2. To maintain high cell viability, prior to seeding, centrifuge cells for 5min at 170x g
3. Discard spent media and re-suspend cell pellet in pre-warmed fresh complete growth media
4. Pipette cells gently to break aggregates
Note: Slight aggregates may be observed, but they are easily dispersed with minimal pipetting and do not impact the performance of the cell line. Alternately, appropriate amount of fresh media maybe added directly into the flask to adjust cell seeding density. However, cell viability might be slightly compromised and decreased by 5%.
Cells should be frozen at a high concentration (e.g., 5-7 x 106 cells/mL) and at a low passage number. The cells should be ≥ 85% viable prior to freezing.
1. Prepare 2X freezing medium (Complete Growth Medium supplemented with 15% DMSO) and store at 2°C to 8°C until ready to use.
2. Determine the viable number of cells and percent viability. Calculate the required volume of freezing medium based on the desired viable cell density per vial.
3. Centrifuge the cell suspension at 170 × g for 5 to 10 minutes. Carefully aspirate & discard supernatant.
4. Resuspend the cell pellet in Complete Growth Medium, and then add equal volume of the cold 2X freezing medium (prepared in step 1).
5. Transfer the cell suspension into cryovials (1 mL/vial). Continue to gently mix the cell suspension to avoid cell clumping and to keep the suspension at a homogeneous state.
6. Freeze the cells gradually at a rate of -1°C/min until the temperature reaches -70°C to -80°C. If a controlled rate freezer is not available, an isopropanol freezing container also may be used (e.g., Mr. Frosty). Store cells at -80°C overnight. Follow manufacturer instructions for freezing cells in chambers.
7. The cells should not be left at -80°C for more than 24 to 48 hours. Once at -80°C, frozen cryovials should be transferred to the vapor phase of liquid nitrogen for long-term storage.