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Meet the Cells – A discussion of some of the most popular cell lines
We recently finished our Ask the Expert discussion on Meet the Cells. This week we had many interesting questions and helpful suggestions on topics including transitioning stem cells to serum-free conditions, moving CHO cells from adherent to suspension culture, dealing with lactic acid in CHO culture, CRISPR for CHO and adapting vero cells to serum-free suspension culture.
This Ask the Expert Session was Sponsored by Life Technologies and features “interviews” with popular cell lines. Life Technologies has a fun interactive way to learn more about cell lines in their “Life of Cells” series, which features the cells as characters with important information, fun interactive contests, and clever videos. Last week we featured a different interview each day and readers had the opportunity to ask questions about some of the most popular cells used in research and manufacturing.
Below is a sneak peek of the discussion. For a full transcript of the discussion, please see – Ask the Expert – Meet the Cells.
We are working on the adaptation of adherent Vero cells to suspension culture under serum-free conditions. Especially the step towards stirred systems showed increased formation of cell clumps, decreased cell growth and, thus, cell stagnation or cell death. Do you believe that an adaptation of Vero cells into suspension is feasible? Which strategy would you target: media design/ optimization or cell adaptation/ luck of getting a clone which finally prevails?
Generating Vero suspension cells, will be a challenge and there are several aspects which will be very important to consider:
- Media should include fluids, which reduce shear forces, if the cells are being grown in a shaking format
- It may be necessary to screen many cells, to find a clone which might have the ability to grow in a suspension format
- It may be necessary to continually passage cells, until the suspension adapated cells finally prevail
- May want to try formulations of media designed for suspension cells
Here is a link with some additional information that may be helpful – http://www.lifetechnologies.com/us/en/home/references/protocols/cell-culture/serum-protocol/adaptation-of-cell-cultures-to-a-serum-free-medium.html
We are trying to transition our iPSCs to a serum free media, how do you recommend weaning and transitioning?
I am assuming you are starting with some fibroblast growth medium like DMEM supplemented with ESC-qualified FBS. If you are using GIBCO Essential 8 medium as your SFM you can transition directly. Essential 8 is designed for feeder free growth. Here is a reference https://www.lifetechnologies.com/us/en/home/references/protocols/cell-culture/stem-cell-protocols/ipsc-protocols/generation-human-induced-pluripotent-stem-cells-fibroblasts.html
If not, there are two ways to do this. Try a sequential adaptation. Assume you are using old media A and want to transition to new media B. Start in media A and know something about the kinetics of growth. Transition to 80%A:20%B grow several passages then move to 60%A:40%B then 40%A:60%B and so on until your cells are in 100new medium B. The other method involves removing 50% of the old media and supplementing with 50% the new media. If you are removing serum you will need to coat the dishes with some attachment matrix like geltrex or vitronectin if you want attachment.
I am looking for a good resource for using CRISPR in CHO genome editing. We are just beginning to look at this technology for improving cell characteristics. Any advice?
Here is a website with background information on using CRISPR for genome editing.
CRISPR-Cas systems have become powerful tools for genome editing and the system as a good choice for your needs. This website also has a short video that will probably be helpful. The CRISPR Nuclease vector is the system for mammalian cells if you don’t have any promoter constraints.