I've recently moved labs and found out we can no longer culture primary cell lines in the designated cell culture labs due to space. However, the normal tissue culture labs has plenty of space and I'm hoping to utilise that instead.
The primary cell lines that I have have been donated from a cell bank and are mycoplasma-free. We have found that these cells can reach very high passage numbers (Over 30!). At which point do primary cell lines stop being primary cell lines?
It is unlikely that your current cell line is primary. Primary somatic cells from humans can only be passaged for a limited number of PD due to telomere loss and senescence due to the tumor suppressors Rb and p53. The primary somatic cells must be maintained.
The typical nomenclature used is not "primary cell line." That is, a cell line is by definition a cell culture that is immortal, or has proceeded beyond replicative senescence, which Hayflick showed happened at about 50 population doubling. Many cell types can senesce before that (~10 doublings). It is better to use the terms "primary cells" and "cell lines" in different contexts. I am not sure what to call the cells you work with, without more detail. It is likely someone may have worked with this cell type before and/or established cell lines from them, so you could look at that literature to see how they used the nomenclature. Good luck Aimee!
Hi Aimee - I agree with Adam above re: nomenclature.
In brief a primary line stops being "primary" when it has become imortalised. (no longer undergoes senescent arrest). Indeed "primary" generaly indicates cells in culture that have come directly from a human/animal (MSCs, PBMCs, cells from biopsies etc).
There is some "overlap" between the two which blurs the definition somewhat. For example if you took a primary line and over-express telomoerase in it this will increase the replication limit of the cells. There are a number of these "cell lines" availabe commercially (and you can make your own with h-tert) but evidence seems to indicate that these are not truly imoratlised and will undergo arrest eventually.
It is a bit strange that they won't allow primary cells but only cell lines in your new lab... I am guessing that they don't have the incubators available for isolating new primary lines (new primary cells are generally quaranined in seperate incubators until they can be shown to be mycoplasma free).
Perhaps if you explained to the lab manager that a) your cells are myco free and b) you will only use primary cells that have been certified to be myco free (as all commercial lines from i.e. ATCC are) and thus do not need a quarantine incubator/hood they may let you use them.
Hope this helps,
Gary
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