Is it necessary to record the passage number of suspension cells, for example AML and ALL leukemic cells? If so, how one should record it since like adherent cultures we don't really split them and pass to new flasks. Instead we only refresh the medium.
The other question in mind is that how long we can continuously culture AML/ALL cells without significant alterations in their characteristics.
Hello
i agree 100% with Damir Khismatullin .
Addition of media will dilute the cells and hence the cells will definitely grow. One can keep on adding media (untill the capacity of the vessel) and not increase the passage
but , if you are removing some volume of cell suspension & adding fresh media then it is a new passage.
Good Luck
https://www.atcc.org/~/media/PDFs/Culture%20Guides/AnimCellCulture_Guide.ashx
https://www.nature.com/nprot/journal/v2/n9/full/nprot.2007.319.html
I strongly agree with the answers already made. If you reach confluency (usually round 1*10^6 cells/ml) viability and characteristics of your cells may change in terms of morphology and growth rate. Depending on the growth rate of your cells splitting the cells in a ratio of somewhat 1:5 - 1:10 3 times a week is (in my humble opinion) a must. I recommend to split them always on the same weekdays so you can easily track back the number of passage you're in and you are more likely to see changes in your cells.
Moreover, I recommend exchanging the culture flask all 4-6 weeks.
I change passage number when I change media. The media change day for my AML cell liens is every 3rd (72 hours) day of medica change.
I agree with the above: you need to split the cells at some point. If they keep growing you will eventually ovecrowd the flask, and then you must split them. How long do you keep them for? Are they a cell line, because then you can split and increase the passage number each time. I have always split mononuclear cell lines once or twice a week, usually at a 1:6 dilution (depending on cell number of course).
Thank you all for your answers. By the way, by not splitting them I mean that we can take out some media (e.g 1/3 or 1/2 n alternate days or daily keeping less than 1- to 2x106 cells per mL which is usually recommended by ATCC for most suspension cells) and replace it with fresh medium unless we don’t really need more cells. So, what I got from all answers is that every time we replace medium that will be count as a new passage? Is that correct?
Yes Sajid, everay time you replace half the medium (or however much you replace) that counts as a new passage. If you just add medium without removing any, then it is not a new passage.
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