Media Adaptation for Suspension Cells

The success of an experiment can rely heavily on the type of cell culture media used. Many choices are available and selecting the right media can ensure the optimal performance of your cells. In certain cases, you may need to adapt your current cell culture to a new medium. Transferring the cells directly into a new medium in one step may be possible, but a stepwise process may be necessary to minimize stress and to retain normal cellular phenotype. To adapt suspension CHO and 293 cultures, The Transfection Experts at Mirus Bio use the following protocol. The general procedure also works well for adapting other cell types to new media formulations.

Stepwise Adaptation of Suspension Cell Culture to a New Medium. To gradually condition cells to growing in a new medium, they are sub-cultured in an increasing ratio of the new target medium relative to the current medium. If cells are not doubling as expected, and/or viability is < 95%, do not increase the percentage of the target medium in the culture. Cell doubling time should be normal and viability over 95% before each stepwise increase. After successful adaptation in 100% target medium, cells may be cryogenically stored in the target medium; henceforth, they can be cultured in the target medium immediately out of thaw.

Protocol to Adapt Suspension CHO and HEK 293 Cells to a New Medium

Depending on your current and target suspension cell media, it may be possible to simply use the new medium during routine maintenance with no special considerations. If the cells do not readily adapt to your new suspension cell medium, try the stepwise adaptation protocol below:

1. As a general guideline, maintain the cells between 3×10⁵ and 2×10⁶ cells/ml.
2. Mix the cell culture medium such that it is 75% current and 25% target media (v/v). Culture cells in this mixed medium until the cells return to normal doubling time and viability is ˃ 95%. This usually requires 2-4 passages. Do not increase the percentage of target medium if the viability is below 95%.
3. Increase the ratio of the target medium stepwise until 100% of the medium is target medium (i.e. culture cells in 50% current + 50% new media, then 25% current + 75% new media and finally 0% current + 100% new media). Only increase the percentage of target medium when cells are exhibiting normal doubling time and viability is > 95%.
4. Cryogenically bank the cells that have been adapted to the new medium.