What is exact definition of Passage Numbers of the cells ?
what is the major difference in deciding passage number of Adherent and Suspension cells ?
The word of passage number or PDL (population doubling level) seems only a threatening to biochemical researchers. I do not understand why cultured cells should die at ca. over 50 PDL. I think that this is only due to the changed nutritional requirements.
Thus, we have recently cultured Caco-2 cells in advanced minimum essential medium (Ad-MEM; Gibco; LifeTechnologies Co., Grand Island, NY, USA) supplemented with 35%FCS, 5 μg/mL of biotin (vitamin H), 0.5% glucose, 4 mM L-glutamine, streptomycin sulphate (0.1 mg/mL), sodium penicillinG (0.064 mg/mL), and amphotericin B (0.0025 mg/mL) in a humidified 37◦C/5% CO2 incubator (file JCB Okinawa). Biotin is already added in William's medium E at 0.5 μg/mL, and is not added in DMEM and Ad-MEM. Since biotin concentraion of adult human serum is 1.95 μg/mL (median; n=4) and infant human serum is 3.11 μg/mL (median; n=6) (see file Feed by measure), we have chosen the biotin concentration of medium at 5 μg/mL. L-Glutamine is not vitamin, but is necessary for some strain (especially transformed cells) to get energy. I think that ferric ions (DMEM contains 0.1 μg/mL of Fe(No3)3-9H2O; Ad-MEM contains 7.5 μg/mL of human transferrin (holo); but William's medium E contains few ferric nitrate (Fe(NO3)3-9H2O) at 0.1 ng/mL and addition by the user is necessary), and some oligosaccharides (not yet identified) may also be necessary. It is noteworthy that lipoic acid (50 μg/mL) is necessary for human cells (HuH-7, T24), but toxic to rat cells (TRL1215, NBT-T2). I also think that ca. 5 nM (1 ng/mL) of mercuric ions (0.05 mM is surely toxic) may be effective to prevent putative ageing which might occur (?) at ca. over 50 PDL, as originally has been studied by an ancient Chinese-Emperor of Shi Huangdi (Qin dynasty; BC 3 C), who has believed that he has reached to the important finding that the mercury is the elixir of immortality.
Hello
Many adherent cell cultures will cease proliferating once they become confluent (i.e., when they completely cover the surface of cell culture vessel), and some will die if they are left in a confluent state for too long. Adherent cell cultures therefore need to be routinely passaged, that is, once the cells are confluent, a fraction of the cells need to be transferred to a new cell culture vessel. Suspension cells will exhaust their culture medium very quickly once the cell density becomes too high, so these cultures similarly require regular passaging . Although regular passaging is necessary to maintain animal cell cultures, the procedure is relatively stressful for adherent cells as they must be trypsinized. We do not recommend passaging adherent cell cultures more than once every 48 h.
https://www.qiagen.com/us/resources/molecular-biology-methods/animal-cell-culture/
https://www.researchgate.net/post/Is_it_important_to_know_how_many_passages_of_the_cell_line_have_passed
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